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ZMA - comperhensive upgrade complete (Read 17938 times)
Archie
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Re: ZMA - comperhensive upgrade complete
Reply #100 - 08/07/19 at 01:01:22
 
Do you have regular fuses back in or are you still using the copper wire?
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Re: ZMA - comperhensive upgrade complete
Reply #101 - 08/07/19 at 01:26:55
 
Still using the 8 gauge ultra pure copper wire in place of the fuse. Though I very much like the peace of mind of a SR Blue fuse (the next best thing according to the crude tests I did) the difference with the copper wire is addictive. I am trapped with this unwise decision. I am not as much concerned about equipment damage. What concerns me most is it being a fire hazard. I take my precautions as with always being around. Always being around will not prevent equipment damage as it happens fast - if a fault develops- that only a poised safety device like a fuse can prevent but I can easily prevent a fire.

Needless to say while testing e.g. after every upgrade I first start with a fuse in and after ensuring stable performance for a few hours usually the next day or two I switch back to the 8 gauge wire. Same when I switched to the KT120s for the first time just in case the they developed a internal short in transportation.
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Re: ZMA - comperhensive upgrade complete
Reply #102 - 08/07/19 at 01:42:06
 
I don't see any fire extinguishers in your pictures.   Wink
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Re: ZMA - comperhensive upgrade complete
Reply #103 - 08/07/19 at 01:53:33
 
I don't think I need a fire extinguisher poised and ready as the probability of a short and a fire is very low after the initial test phase.

Only if I leave the area and the initiating small spark propagates (there is very little highly combustible material internally in the ZMA) then there could be a fire hazard. Since I am around at the smallest sign of trouble I just need to turn it off.


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Re: ZMA - comperhensive upgrade complete
Reply #104 - 08/07/19 at 23:07:44
 
Expanding on the safety issues with a wire in place of a fuse. The reason I am kind of comfortable doing it is the probability of a fire is very low. In decades I have never seen a stable equipment suddenly catch fire. It is more likey that any piece of equipment will open circuit (a resistor or capacitor or diode aging ) and die rather than spontaneously catch fire.

The reason manufactures put a fuse is out of abundant caution, Murphy's law being what it is. And that is why I also don't leave it unattended for long periods. Besides being a tube equipment a little more caution is a good idea.

Also manufactures install fuses incase customers make mistakes like dropping coffee or metal pins into the equipment when running or overloading it etc.

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Re: ZMA - comperhensive upgrade complete
Reply #105 - 08/08/19 at 22:57:09
 
Learning 5:

Having done many changes over a short period of time, I have refined a a method for judging effectiveness of an upgrade.

When trying to ascertain whether an upgrade was effective one has to make a concerted effort to remember that change by itself in not an indication of greater accuracy and to try to objectively judge if it is just change that one is perceiving. Very often because we psychologically want improvement to show up being humans it is possible to perceive change as improvement and pat ourselves on the back thinking that money and time was well spent. In a way I am thankful to Bybee "quantum" products for teaching me this until it finally dawned on me a year or so later. E.g. A/B testing soon after buying the Bybees compared to how I perceive them now is different having lost the initial expectation from the hype by the manufacturer. This is more likely to happen if one has no reference point to gauge with. Because after an improvement is also a change. I have over time realized that, that reference point for accuracy is live music and not another higher end system.

While comparing between systems or before/after an upgrade, it is often helpful to isolate each instrument mentally and decide if a saxophone's sound is close to a real saxophone, likewise for other instruments and voices. To this point I very often find judging the sound of an applause, catcalls and all (of all the things!) to be a better indicator for judging accuracy. Live applause seems to be more layered being densely packed with humans shoulder to shoulder and front to back with each point in the soundscape producing a different frequency and all in a tight midrange.

This is my own technique developed over time about dealing with judging if an upgrade is effective. It will be great to hear and learn from you everybody and especially Steve as he has been voicing his builds for donkey’s years now.
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Re: ZMA - comperhensive upgrade complete
Reply #106 - 08/11/19 at 01:08:22
 
Learning 6:
 
Ensure all electrical connections (power and signal in/out) are excellent: I noticed the difference  good quality connections make by chance (well sort of, as this is a no brainer): when I decided to up the power capacitance to 13,500 uF per side during the feasibility phase to ascertain viability my planned configuration, I connected the 3 large capacitors (6800uF, 4700uF and 2000uF ) with ordinary wire that was lying around and as well the connections were temporary without crimping eyelets (in fact with alligator clips), soldering, spring washers under screws etc. (see picture in post #54 on this thread where the capacitors are placed on top of each other with loose dangling wires). Then on successful testing like this for quite sometime I made things permanent (see picture in post #86) viz heavy gauge Duelund wire, crimping eyelets, spring washers under screws, soldering, the used of Stabilant 22 on connectors etc. Just improving the workmanship as far as connection quality improved the SQ especially in the bass area. This turned out to be a good test for demonstrating what connection quality can do. In the first instance the connections were temporary hence not much effort was spent on them while in the second case no holds bar connections were made: I can categorically say the difference quality connections made was enough to be noticeable without straining to find if in fact there is an improvement.

On that note I think the application of “contact enhancers” for power supply connections like IEC, power capacitor screw connections and as well for the signal pathway like RCA jacks, speaker binding post, tube pins help more in preserving the contacts from oxidizing over time more than just improving the contact quality. The former benefit more than the latter. In fact I could not discern before/after difference for contact enhancers i.e. was too small to gauge properly. I use 2 types of contact enhancers: Stabilant 22 for the power supply path way e.g. IEC prongs, and power capacitors and Craig Doxit Gold for low power signal type connections like RCA, speaker jacks and tube pins. These compounds more importantly prevent the contact surfaces from oxidizing over time thereby resulting in a reduction of the coefficient of electrical conductivity across the connection with every passing month.

Another point is w.r.t. soldering. I use 4% silver solder and before soldering ensure the there is a physical mechanical connection (twisting together and/or crimping) , then applying the solder to only a portion of the connection the other portion left mechanically in tight direct contact with each other without solder in between.

Another best practice: heat is the worst thing for capacitors life expectancy. It affects the capacitors dielectric medium. So when soldering capacitors draw away some of the heat input by applying an alligator clip with a bare long copper wire connected to it between the solder point and the capacitor.
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Re: ZMA - comperhensive upgrade complete
Reply #107 - 08/13/19 at 02:26:13
 
Expanding on contact quality mentioned in the above post.

This is the reason for my resulting in dumping all attenuator bar one in the entire audio chain (have one at source equipment only) as for me they are the single largest cause of electric pathway degradation. The wiper leaf spring force attached to the knob spindle has to be deliberately designed to be inadequate (from conduction point of view) to allow easy turning of the knob by weakest of fingers in a given population (male, female, adult, teenagers, children) i.e. if I were designing one I would design it such that a kid (just because an adult may not want to be separated from the cozy chair and askes his kid to turn it for him). Because as a designer I know lay people are not thinking of signal conduction but "who is that moron that designed it to make it so hard to turn". The effect of inadequate spring tension is like not tightening the screws tightly on the capacitor connections. Compounding this weakness in contact integrity is that the attenuators are in the signal pathway - the most delicate, fragile and sensitive of all the electrical currents flowing within an amp. Had they been in the power supply circuits instead the shear magnitude of the current would have bamboozled through this weak connection but alas it has to be in the weakest and the most sensitive pathway.
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Re: ZMA - comperhensive upgrade complete
Reply #108 - 08/17/19 at 12:36:11
 
More on the impact that enhanced electrical contact make. This is a nice one.

Here are some pictures of my dismantled 19 year old Yamaha DSP-A1 7 channel home theater amplifier that I absolutely love. It was Yamaha's  Flagship HT amp at that time was a reference amp by which all other HT amps were compared to. I still prefer it compared to modern day amps ATMOS and all.

I recently completely dismantled the amp one PCB at a time, cleaning each board meticulously with vacuum and light air pressure on the PCB surfaces, the gold edge connectors (male and female) with an eraser and electro clean (carbon tetrachloride) and applied Craig DeOxit gold to the connectors. There were about 15 PCB boards in all large and service different purposes. The intent of the overhaul was to removed all traces of dust on the surface of each PCB paying special attention to the dust between what seem like 100 or so micro connectors on all four sides of each IC (Integrated Circuits chips) and there are many of them. I think you know what I am talking of. These connections from each of the IC's to the board are so small and so close together (0.01 mm apart) that when dust settles between them it causes unintended micro currents to flow between them kind of partially bypassing the designed intended paths through the circuit board, thereby affecting performance.  

This is such a complex amp that I took 2 days to do it all.

Also I inspected each PCB board and found on one of the boards that there were hairline cracks (like 30 of them) on the pin to board solders and these pins are about 0.5 mm apart – slightly better than IC connectors. I soldered the pins back. But boy soldering anything inside a point to point amp like the ZMA or CSP3 is cake walk compared to soldering the close proximity pins on a PCB that is designed to be done by robots. The picture of the lone PCB (upsidown) shows the pin solders that had micro cracks.

As well all RCA connectors and speaker jacks were thoroughly cleaned one by one inside out with electro clean and then Craig's DeOxit Gold applied to them.

The Volume potentiometer and the program selector switches were also flushed with electro clean spray and spray version of Craig DeOxit applied to the internals of the pots.

While at it I also replaced the power cord and fuses with audio grade ones.

There are no words to describe the improvement. So I'll just exclaim. Wow! Wow! Wow!

Well I explain: movies on my 7 speaker surround sound system are on a different dimension now even though it was very very good before the clean up. I find that sound plays a larger part than vision (the large screen UHD TV) in ones movie immersive experience. Truly sound rules over visual effects. I am not discounting the TVs influence and needless to say having both good sound and a good TV will be even better. But for immersiveness sound subliminally enhances the experience.

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Re: ZMA - comperhensive upgrade complete
Reply #109 - 08/17/19 at 12:40:35
 
PCB that had micro cracks on the solder pins on both the top edge and bottom edge pin lines. Soldering these without shorting the adjacent pins was something else. On the other side of the PCB are the micro LEDs (dot matrix) that gives information on the front display so they heat up a little bit causing the pins to expand while running and contracts when turned off. The many on/off thermal cycling over 19 years caused the solders to fatigue and crack.
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Re: ZMA - comperhensive upgrade complete
Reply #110 - 08/22/19 at 21:29:52
 
Learning 7:

This topic is on burn in period.

As you know in the past 3 years I have done numerous component and device changes and thus had many opportunities to note how much burn in time is required for a new device or component to stabilize to an improved SQ stable state. I found that the majority of changes due to burn in happen in the very first half an hour. Then it continues on a time scale that is logarithmically less and less for the next 2 or 3 times the device or component is started up and run. So, in terms of number of hours in total I can reliably say my experience is that I cannot discern changes/improvements after 6 to 10 hours in total and that’s being generous. This I found is applicable for everything from vacuum tubes, to capacitors, to resistors, diodes to whole devices.

I wanted to figure out why burn in causes a changes in SQ and wondering if the answer to it might be more objective than to subjectively claim that a certain burn in period is necessary. After much thought I am inclined to think it is because of metallurgical changes that the metal undergoes on being heated on powering up since nothing else e.g. geometry of the components changes.

Consider the burn in of a vacuum tube (applies to other components as well – capacitors, resistors etc.), within the first 30 minutes of powering up the temperature will have reached the operating temperature from initial room temperature. The internal temperature of the plate, cathode and grids is I estimate roughly about 300 C (572 F) to 600 (1112 F) depending on their proximity to the filament. while the filament is about 3000 C (5432 F) (because the colour of the filament for that material (tungsten) is an indication of its rough temperature, e.g. if it glowed white instead of red (infra-red) it would be even hotter).

It is well know in the wider industrial world that heating metals brings about metallurgical changes at the molecular and crystalline level. Heat treatment is in fact required by national standards and codes such as ASME for critical applications to get the desired properties in metals: malleability, ductility, hardness, toughness, fatigue life…..

Coming back to the audio, this heating on powering on relieves internal locked in stresses that have resulted from cold working the metal (cathode, anode, grids, filament) i.e. bending and hammering to form the plate/grid/cathode shape during the manufacturing process. The raising of the temperature to those levels will cause intra-granular changes in the microstructure of the metals. I believe it is these metallurgical changes and the resultant stress relief that causes these improvements during the burn in period. However these molecular level changes happens largely the first time the device is brought up to its working temperature. Those stress originally caused from the cold working process, do not come back unless the metal is worked on again. This theory also supports the shorter period I am actually seeing that is required for burn in.

The only thing that happens further after 5 to 6 hours is the slow process of aging associated with thermal cycling resulting in fatigue failure and slow oxidation (in spite of the vacuum conditions within the tube) and finally the tube fails and its time for new tubes, capacitors etc.

I now after much experimentation and observation feel that manufactures tout 400 hours of burn in to avoid returns and it’s a way of guiding our expectation that perhaps its not good enough now but will get better in the next 100 hours and the next 100 hours and the next and before you know it its 6 months from the time that device was bought and we lost the initial reference point to decide if in fact there was a improvement so we just assume so because that's what they said so or we move on to the next thing that has caught our fancy.
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Archie
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Re: ZMA - comperhensive upgrade complete
Reply #111 - 08/22/19 at 22:37:03
 
Your burn in take is cynical but I suspect correct.  For myself, I lose my reference super fast and despite things being improved, I start to think it doesn't sound as good as time goes by as I get used to the new normal.  Capacitors ought to be different than tubes since the materials are more "organic" and presumably flow with heat.  Do you find the same 5 to 6 hour window for them?
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Re: ZMA - comperhensive upgrade complete
Reply #112 - 08/23/19 at 00:35:20
 
On re-reading the last paragraph of my explainaiton I admit it came out that way. But it was not meant to be cynical. Just trying to figure their motive as the figure of 400 hours does not match my experience by a large margin. I wanted to figure out if there is any other reason that figure might be touted. My reason could be wrong that is why I said I feel that that is the reason they are quoting that figure.

Regarding Capacitor burn in. I found the same period of 5 to 10 hours applies. Sure the dielectric medium which btw may or may not be organic (not all are beewax and oil based). But in any case I am not talking of the dielectric medium but talking of the positive and negative plates. In high end capacitors there are yards and yards of copper, silver or metalized films (tightly coiled) within so still the same applies. The operating temperature is not even close to that of the tubes agreed but than again there is far less - if any - cold working performed on them during their manufacture as well the plate thickness is a few microns for the low voltage ones and power caps higher voltage and current ones will have thicker but still a fraction of a millimeter plates. So in my opinion do not require hundreds of hours of burn in.
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Archie
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Re: ZMA - comperhensive upgrade complete
Reply #113 - 08/23/19 at 00:47:16
 
Even if you were being cynical, I didn't mean it as a fault.  There is more snake oil than snake these days.

I personally concur with your short burn-in findings.  But I always figured it was my lack of discernment.  The metallurgy explanation makes a lot of sense to me.  Do you feel the same way about ICs and other low heat devices?  Do they burn-in at all?  I don't personally hear a change with time for these kids of things.
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Re: ZMA - comperhensive upgrade complete
Reply #114 - 08/23/19 at 01:18:46
 
I think ICs themselves being silicon wafers in PNP or NPN junctions will not require burn in. Besides these chips operate at less than 5 volts DC. But the ICs are usually not in isolation there are always capacitors, resistors of various kinds on the same board so that device as a whole will require some burn in. Do not forget the transformers within SS devices with miles of wire with varnish insulation those will require burn in the most, though again I have a hard time with 400 hours.
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Archie
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Re: ZMA - comperhensive upgrade complete
Reply #115 - 08/23/19 at 01:31:44
 
Sorry, I used IC to mean interconnect cable and not integrated circuit.   Embarrassed
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Re: ZMA - comperhensive upgrade complete
Reply #116 - 08/23/19 at 02:10:54
 
That was funny, I went off on a tangent on a completely different subject.

Interconnects (IC), I have a slightly different take on. They call it burn-in. But to me burn-in in the true sense does not apply here as the voltage and currents are so very small that the wire metal and the insulation for all practical purposes is not affected. That is why you and I do not notice a change. With years there is a change in SQ but that I think it is not primarily because of burn in but due to aging the metal and insulation undergoes chemical changes being exposed to air.

But what matters for IC is the wire quality (material and purity) and the insulation which together tends to act as a capacitor. So choice of ICs is more of a consideration than burn in. A good IC will sound good from day one.

Speaker wires are exposed to higher voltages than ICs so there might be some burn in but again not so much to even think of it. Again I think here choice is more of a consideration and if its a good wire it will sound good from day one, with minor changes over time if at all and these change are not worth talking about. Again aging applies here as with the ICs.

I noticed power cords do change the sound with time. It makes sense too that power cords undergo burn in and will be better with time say over 50 to 100 hours - not 5 or 6 hours definitely. But even here choice of a cable really matters more than burn in (wire quality and insulation) but burn in does play a small part more than for an IC or speaker cable.

N.B: Ageing makes the wire worse off (oxidized copper or silver will conduct less) but is measured in years rather than hours where as burn in improves its qualities but happens over hours.
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Re: ZMA - comperhensive upgrade complete
Reply #117 - 08/23/19 at 05:20:45
 
Bonny,
I definitely feel the burn-in phenomenon is "type-specific."  You raise some interesting points of discussion with regard to voltage and burn-in effect.  I can't say that I disagree that  the long stated burn-in periods  from vendors are a product of sales/marketing to exceed the customer's trial period.  I have often been suspicious of these prolific claims.  

One thing I do want to comment on has to do discussion on oxidation.  Copper Oxide (CuO) is a very poor conductor.  If you have in your system, raw exposed copper, then you must be aware of CuO and rid it as it develops.  It is not a great conductor, so as you consider skin effect, CuO is the enemy.  

Silver on the other hand does not share the same inherent handicap.  Silver Oxide (Ag2O) is in fact a great conductor.  That said, one need not worry about their raw and exposed silver cabling oxidizing like is the case with copper.  Ag2O is a great conductor and scientifically proven to conduct as well as Ag.  

What does this mean?  Well, that depends.  If you are using interconnects or speaker cabling with raw metals that are exposed to oxygen, then it is important to know if the Oxide of that metal type will have a detracting effect on the signal, or not  Ag20 is nothing to worry about.  
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Canary Audio Grand Reference Monos//ZMA//Zen Ultra//Taboo MKIII//Waversa DAC3//ModWright Oppo UDP-205// PS Audio P20//Canary Audio MC-10//Van den Hul Colibri "Stradivarius"//FFYX T1803 TT//SonoruS Reel-to-Reel & tube playback preamp//Tannoy Westminster Speakers
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Archie
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Re: ZMA - comperhensive upgrade complete
Reply #118 - 08/23/19 at 16:11:46
 
That is my understanding about silver oxide as well.  My silver speaker wire ends are quite tarnished.
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Re: ZMA - comperhensive upgrade complete
Reply #119 - 08/23/19 at 21:17:03
 
Jeff, aging is measured in years anyways v/s burn-in which is in hours so aging is less of a consideration.

I have not checked the resistivity values of Ag v/s Ag2O I'll take your word that they are equal. To me they should be different perhaps not by much but I being a nitty gritty person and wanting to squeeze every ounce of performance that even a small difference between the two will drive me to do something about it. That is why I buy 6N or 7N silver wire instead of 5N or less. The difference in conductivity here is even less I would think than oxide/no oxide on silver, but I still do it because for interconnects and internal signal wires from the RCAs to the input tubes (mentioned in one of my earlier post on this thread) I like to preserve the delicate input signal as much as I can.

Having said that both gold and silver being noble metals do not oxidize unlike copper. The tarnish you see on silver is more of a sulfide than oxide. Sulfide I believe is a bad conductor therefore e.g. RCA connectors are not usually plated with silver but gold (gold being a more noble of the two metals resists reaction with chemicals in the air).

You made a good point on metal inside of insulation being oxidation free. That is a good discussion point. My take is oxidation happens not only to exposed wire but also to the insulated portion (at a much slower rate) of the wire. This is because of permeability of the insulation. If you have any spare 10 years or more old wire strip off some insulation and you will see that there is an oxide/sulfide layer or what ever have you with the pollution in the air these days. If you use a sand paper on it you'll than expose the parent metal.
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Re: ZMA - comperhensive upgrade complete
Reply #120 - 08/23/19 at 22:50:11
 
Interesting.  I've read consistently that silver oxide conducts better than silver itself but no where that silver doesn't oxidize and that the tarnish is, in fact silver sulfide, which is a poor conductor.  It just goes to show that "information" on the Internet can be very misleading.

I'll clean my cable leads and try some Graphene contact enhancer on them.  Maybe this will protect against future tarnish and maintain a better contact.
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Re: ZMA - comperhensive upgrade complete
Reply #121 - 08/23/19 at 23:10:58
 
What we all experience with exposed silver is Oxide. Oxide is a chemical compound formed when silver and oxygen react. That is the tarnish on our untreated, exposed silver cabling and interconnects.

And you are correct Archie, research has shown that the oxide of silver is actually a better conductor than pure silver.

As far as silver sulfide, that would be extremely abnormal. Sulfur is not generally present in ones home. If it was, you would smell it!  :-[  Silver Sulfide can only form when silver is exposed to sulfur and they react, forming the compound Silver Sulfide.
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Canary Audio Grand Reference Monos//ZMA//Zen Ultra//Taboo MKIII//Waversa DAC3//ModWright Oppo UDP-205// PS Audio P20//Canary Audio MC-10//Van den Hul Colibri "Stradivarius"//FFYX T1803 TT//SonoruS Reel-to-Reel & tube playback preamp//Tannoy Westminster Speakers
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Re: ZMA - comperhensive upgrade complete
Reply #122 - 08/23/19 at 23:29:14
 
Jeff, everything I just looked up said that silver tarnish was silver sulfide.  Can you post any links to clarify this?  Here's a typical one that I found:

https://study.com/academy/lesson/what-is-silver-sulfide-chemical-formula-uses.ht...

There's also Wikipedia.
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
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Re: ZMA - comperhensive upgrade complete
Reply #123 - 08/23/19 at 23:41:28
 
Ha! I stand corrected.  Bonnie is right in that the tarnish is in fact a Sulfide.  I just learned that it does not take much environmental sulfur concentration to form the tarnish on silver. Tarnish on  copper is in fact a product of oxidation.  

I guess there has been too many decades since my last college chemistry course  ;D

Thanks Bonnie and Archie.
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Re: ZMA - comperhensive upgrade complete
Reply #124 - 08/24/19 at 00:16:18
 
Jeff,

I had to waft away a few layers of foggy memory myself.

Cheers,
Bonny
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Re: ZMA - comperhensive upgrade complete
Reply #125 - 08/24/19 at 00:41:53
 
Thank you guys!  What's amazing is that every site I've seen about using silver wire sights the fact that silver oxide conducts better than silver.  Yeah, so ... ?
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Re: ZMA - comperhensive upgrade complete
Reply #126 - 08/24/19 at 04:52:09
 
Quote:
Jeff,

I had to waft away a few layers of foggy memory myself.

Cheers,
Bonny


No kidding...LOL.  And Chemistry was my favorite subject going into college.  

That, and I am in an industry where oxidation is our product's #1 enemy, so I guess I am jaded. Sorry Oxygen.  I still love you very much and need you dearly in my life.  Damn you Sulfer, coupled with HsO.

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Re: ZMA - comperhensive upgrade complete
Reply #127 - 08/24/19 at 23:29:11
 
Jeff, Archie:

In the bargain we (well you both) might have discovered a brand new method for enhancing audio performance further. If silver oxide is a better electrical conductor than pure silver what if we deliberately accelerate the oxidization of silver? Because silver is resistant to oxidation in air what if it is exposed to higher concentrations of oxygen, say the oxygen used by medical patients or if it is available from somewhere else?

But for the life of me, I am finding it difficult to find the actual value of resistivity of Silver Oxide unlike you Jeff, Archie.

For pure silver it is 1.59 × 10−8 Ωm at 20C what did you find the value is for Silver oxide?

If the value is lower as quoted by a accredited lab or research paper I might try exposing a pair of silver cables to higher levels of oxygen if I can find it easily.

I mean we buy cryo treated cables and all kinds of things so why not expose silver wire to concentrated oxygen if that will squeeze more performance?

Sounds crazy now, even far fetched, but you never know it might be the next rage just like cryo treatment has now firmly established itself.

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Re: ZMA - comperhensive upgrade complete
Reply #128 - 08/25/19 at 00:06:28
 
I did find this paper that seems to list conductivity for silver oxide but damned if I understand any of it.

https://www.researchgate.net/publication/275152334_Electrical_and_Optical_Proper...
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Re: ZMA - comperhensive upgrade complete
Reply #129 - 08/25/19 at 00:58:15
 
Sorry to report that, that research paper does not apply to our discussion. It applies to electron beams and their propagation (conduction) in optical media with varying thicknesses of Ag2O applied to the surface not really to transmission of electricity in conductors such as wires.
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Re: ZMA - comperhensive upgrade complete
Reply #130 - 08/26/19 at 23:52:08
 
Steve,

Now that I am essentially running two of the Torri II mono's in a single chassis with KT120 tubes (these tubes are glorious - the ease with which they drive my 89dB speakers (24Hz to 150 kHz) is something else compared to KT88s) I cannot but help recommend to you to start another product line: ZMA II with 60W output.

Currently you have the ZMA line and than there is a huge price difference for the next product up, the Torri II mono pair. The new 60W ZMA II with KT120 as the primary tube (it is designed around), would nicely fit between these two extremes, I think.

Besides the price the other advantage for buyers is the use of only one audiophile power cord which is a huge saving in itself.

Something tells me you'll sell more of these than the Torri II monos because with 60W at one's disposable there are less restrictions on the type of speakers one can use and being at a lower price point (due to optimization of material - one chassis, power supply peripherals) and yet with performance rivalling that of the mono's will help (depending on the parts chosen off course).
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Re: ZMA - comperhensive upgrade complete
Reply #131 - 09/09/19 at 00:35:24
 
Learning 8:

I have found that turning ON the ZMA about 15 to 20 minutes before actually starting to play music is the quickest way the amp reaches its sweet spot.

I have consistently found that if I start playing music right away it takes longer to get to the sweet spot and the louder I start playing music from the very initial time the power is turned on the longer it took to reach a point where the SQ stabilizes to that fantastic level.

This phenomenon may be unique or more appropriately exaggerated in my ZMA because I have an inordinate amount of power capacitance: to remind every one it is 13500 uF per side.

On another note the experience with adding capacitance has affected my belief in it so much that I have now ordered extremely fast oil capacitors that I am going to add to the 13500 uF. I am limiting these oil caps to only 70 uF (even at 70 uF they are huge in size) as the objective here is not to add further storage of power (diminishing returns on that front) rather to compliment the already large capacitance currently present. By adding even more speed to the “power package” to deliver the very first micro burst of supply power as and when demanded before the other larger capacitors take over.
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Re: ZMA - comperhensive upgrade complete
Reply #132 - 09/13/19 at 23:28:06
 
The Obbligato Film oil 70 uF caps have arrived. I was surprised at the physical size of the capacitors. Inspite of just being 70 uF they are 5 inches in height and slightly over 2 inches in diameter !

I have not installed them yet but just thought a picture along side my largest cap the 6800 uF Mundorf Mlytic 4 pole caps which themselves are huge would be of interest. It may be hard to see in the picture being of the same color as the Mlytic cap in the background.

Cannot wait to install them and find out the results.  I don't expect any spectacular change though but more nuanced. I believe it is small details such as these that will contribute to making my supercharged ZMA even better especially when playing fast dynamic music. Let's see ….
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Re: ZMA - comperhensive upgrade complete
Reply #133 - 09/27/19 at 22:12:16
 
Learning 9:

Obligatto Film Oil Power caps install:

These are true metal (aluminum) film capacitors filled with oil. Not pseudo film caps such as metalized polypropylene. Copper or silver film would be better but the price increases substantially and for power supply silver would perhaps be an overkill unless you have money to burn. I must confess buying the Obligatto caps was by chance. I bought these only because these 70 uF ones were 50% off in price and thought why not try them out.

For small 70 uF capacitors they are pulling above their weight. I am tired of extolling the benefits of this and that, but these definitely are making the highly modded ZMA even better. Had I experienced what I am now, I would have bought the largest Film oil cap(s) that would fit in the capacitor opening in the ZMA top plate when I first replaced the large red Mallory 2000 uF power capacitors with Mundorf Mlytic 4700 uF HP+ 4 pole capacitors. These turned out to be even better than the Mundorf Mlytic’s 4 poles for imparting added dynamism.

I am still wrapping my head around as to how the relatively small value 70 uF Film Oil caps brought more air, depth, timing and agility to an already fantastic output.

Which led me to do a bit of experimentation:
To zero in on the contribution from the film oil caps and get acquainted with their properties I disconnected all of the 13500 uF of capacitance and only left the 70 uF oil film caps in the power supply. Intent was to enable comparison to the 13500 uF of electrolytic capacitor aggregate setup that I was well familiar with by now. I can say that this was perhaps the biggest learning for me thus far. For almost all of the other upgrades mentioned in earlier posts above I would say they came out as expected with no major surprises as they were careful calculated buys (except perhaps the Bybee purifiers).

These oil film caps at only 70 uF improved dynamism better than all the 13500 uF electrolytic caps put together even considering the fact that mine were the top grade 4 pole low ESR/ESL 4 pole Mundorfs Mlytics. These relatively small oil film caps resulted in the timing being more to the point. There was a loss of air and extension and noise floor increased. I think this is because of the low value of capacitance them being alone. I am certain if I had oil film caps with a total of 13500 uF or even 3000 uF the results will outstrip the 13,500 uF electrolytic caps.

I than installed the 13500 uF electrolytic capacitor aggregate back along with the 70 uF oil film capacitors. This setup was the best, better than either alone. Together the background got lowered considerably also besides enhanced airiness and that all important timing improved palpably.

As mentioned earlier but worth repeating with perhaps more detail and perspective. I wish I had discovered these earlier, before I purchased the Mundorf caps (6800 uF and 4400 uF costing about $800 in all) I would have instead bought the largest oil film caps that I could fit. The oil film caps are 3 times the physical size compared to an equivalent capacitance electrolytic cap. I do not think I could fit an oil film cap greater than 600 uF in the same place as the original 2000 uF Red caps. But I believe 600 uF of oil Film caps would be awesome.

In hindsight, I now think there is no point in having large capacitance caps if they are slow (high ESR). Music is all about timing. Fast caps do not allow the circuit voltage to sag during instantaneous demand spikes while the music is being played (a deep bass note here and there, rhythmic bass notes and other demands such at another micro instant more than normal number instruments / voices output higher demand notes together). When the amount of instantaneous required power supply is not forthcoming at the instance it is needed that is a lost opportunity and is fleeting and timing of the music is affected due to circuit voltage droop. By the time the slower electrolytic caps (even though they may be very large) respond the train has already left and having missed the train the power supply now is always playing catch up thus affecting timing. Mind you the Mundorf Mlytic 4 Pole caps are way faster than the original stock ZMA red Mallory caps and resulted in improvements mentioned earlier in this thread but these oil film caps are in another league in terms of speed. The very best would to install very large fast oil film caps and the larger the capacity and fast the caps are gives greater isolation from the grid (the noise floor becomes eerily quiet) while not causing a depression in circuit supply when demand increases due to faster charging/discharging cycles.

Now I can say that ideally all of the power capacitors should be oil film type. But that would mean capacitors physically the size of the whole footprint of the ZMA amp (I think) since film oil capacitors size  to power ratio is very large. So given that space is a constraint, a hybrid mix of oil film and electrolytic caps would be the solution. This way the faster oil film caps will serve the initial micro burst of power demand while gargantuan electrolytic caps can than take their sweet time continuing to maintain the downstream circuit supply.

I’ll slowly be adding more film oil caps to my capacitor aggregate in the power supply, perhaps even remove the red Malory 2000uF caps to accommodate the new caps.

Sometimes good things happen by chance.
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Re: ZMA - comperhensive upgrade complete
Reply #134 - 09/28/19 at 04:59:38
 

I have always noticed there is some correlation between a capacitors performance and it's physical size.  That 70uf cap probably has the nuts of 700uf of electrolytic or more even though it would be hard to measure (unless you use your ears of course).

Even when voicing my amplifiers, a physically larger film cap of a smaller value can often be used instead of a physically smaller film cap of a larger value and yield the same results.

Steve

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Re: ZMA - comperhensive upgrade complete
Reply #135 - 09/28/19 at 22:54:41
 
I do not have as much experience with swapping different types and sizes of capacitors as you Steve (not even close), but now that you mention it I can recall feeling the same: physically larger film caps have more whoomph than smaller ones of the same capacitance value e.g. in the above case of the Obligatto Film oil cap install and earlier when I installed the 47uF Mundorf Tube caps in place of equivalent capacitance F&T electrolytic caps.

In the power circuit of an amp I generally tend to go for the largest capacitor value based on what will fit physically and quote the size in terms of capacitance i.e. the largest value possible in order to achieve battery like power supply conditions. But also the Time Constant T (tau) of a capacitor is perhaps more important in the power and signal circuits. Where as very specific capacitance values are required in the noise filtration circuit (which of course is a subset of the power circuit) to filter out specific frequencies of noise (e.g. 120 Hz noise from a fast full wave solid state diode based rectifiers or very high frequencies from switching power supplies from other equipment in the house or neighbors or an electric arc furnace in a foundry in the town somewhere).

A lot of experimentation and expense can be avoided if manufactures of capacitors meant for house hold equipment give extensive specification details including the time constant and ESR/ESL values. Very few if any do that. They generally only specify the capacitance value, the temperature rating v/s life in hours and some times if ever the ESR/ESL values and almost never the Time Constant (Tau) of a capacitor and talk in terms of sweetness, mellowness, warmness and other adjectives. I must admit these adjectives do not help me at all in buying decisions as these are subjective even to the extent that someone's sweetness is another person's mellowness. I also have a hard time with what sweet , warm sound etc,.is.
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Re: ZMA - comperhensive upgrade complete
Reply #136 - 10/27/19 at 22:53:08
 
Further improvement in the ZMA power supply:

The itch to get more out of the ZMA continues.

For the longest time I was thinking the power rocker switch was a weak spot in my heavily upgraded ZMA power supply chain. See upgrades to Power supply mentioned earlier in the very first post in this thread for stuff already done to the power supply before. More so given that my souped up ZMA is now drawing more current: from 4 to 5 Amps before to 7 to 8 amps I felt I needed to do something about it. I was hesitant up until now mainly because to access the original power switch was difficult being buried underneath a mass of capacitors, resistors, wires and bus bars. All these needed to be cleared and then re-assembled for this task.

Rationale for this upgrade:
Switches and circuit breakers over time tend to pit and carbonize at the contact points. This is because when the switch is opened (when turning a device off) as the gap between the contacts is increasing as it travels from fully closed to fully open position there is arcing between the moving contacts until the gap become large enough as it approaches the open end stop to the point that the arc cannot jump across the contacts. The larger the current the more the arcing and slower the opening the longer the arc is sustained. A bit of learning from the electrical industry at large: Industrial circuit breakers that handle thousands of amps of current have arc chutes, air blaster and for even higher current handling the contact points are enveloped in pressurized SF6 (sodium hexafluoride gas) to quench the arch and are also extremely fast as the circuit breakers open (blasted open by extremely high pressure (> 6 MPa) nitrogen). This arcing causes pitting on the contact surfaces thereby progressively decreasing the effective contact area over time. In turn this decreases current flow during subsequent normal operations and is worsened by the fact that the arc also causes very slow (over years) carbonisation of the contacts.

What is done:
In light of the above. I installed a heavy duty double pole (20A each pole) toggle switch (DPST switch). This particular switch (Russian heavy duty old world type) was chosen due it being mechanically fast and and as well makes and maintains forceful contact. I installed the DPST in parallel with the original 15A (I think) rocker switch. I wired both poles in the DPST such that current flows though both poles and also thorough the original rocker switch making the switch combination able to handle 55A at 250V AC. Far in access (@ 7 times) of the steady state current draw but this huge current handling ability should hugely handle large micro burst of current without chocking.

Proof of the pudding is in the eating:
I can now easily test the efficacy of this upgrade because of the ability to power the ZMA in various permutations and combinations i.e. using the original rocker switch only, or only the new double pole toggle switch or both together. In trials the consensus is that when demanding music is being played and this so at loud volumes the new DPST switch and the original rocker switch when used together as compared to the new double pole used singularly has no perceptible difference in the sound dynamism. But when the double pole switch is compared to original toggle switch each used singularly the difference is more than subtle. The double pole toggle switch wins handsomely, the sound quality difference is more perceptible especially with demanding music (heavy metal fast music – not that I listen to heavy metal much – used only for testing). Though not so perceptible with lighter music it feels more liberated with the use of the new DPST.

Usage methodology:
To minimize wear and tear of silver contact surfaces (from arcing) on the new double pole switch (to keep its contact clean longer) I first switch on the original rocker switch and than when the initial inrush of current subsides I bring in the double pole switch. For turning off I first turn off the new double pole switch and than the original rocker switch. This way the DPST is opening/closing with minimal arching due to the parallel pathway of the original rocker switch.

Cost of upgrade: $20 ….. worth it.
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Re: ZMA - comperhensive upgrade complete
Reply #137 - 11/15/19 at 02:27:39
 
An attempt to lower the internal temperature for longevity of capacitors.

Patterned holes drilled in the bottom panel - see picture.

Was not comfortable with the fact there was no ventilation of the internal space. Especially as the base is made of wood which is a poor conductor of heat compared to a metal enclosure. Most audio equipment has metal enclosures, as well as ventilation slots all around.  The metal enclosure dissipates heat through conduction (along with internal heat sinks) and the ventilation slots dissipates heat by convection.

Those look like they are too few holes to make a substantial difference but there was no point as the openings at the top were limited to those around the two large capacitors where they protrude through the top plate. The cross-sectional area of the sum of the holes in the bottom plate is about 2 times the circumferential gap around the two large capacitors at the top plate. The 4 pole 6800 uF Mundorf caps are about 2 mm smaller in diameter as compared to the original red capacitors which helps with the ventilation.

I do not think this will decrease the internal temperature by much (have not taken before and after temperature measurements) but it is better than being sealed, I thought.
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Re: ZMA - comperhensive upgrade complete
Reply #138 - 03/22/20 at 02:45:48
 
Hi folks,

Just thought I'll report that my ZMA with all that has been done is doing well. No issues in spite of it pumping out 60W per channel for more than 6 months now.

Haven't done any more upgrades on the amp since the last post in November of last year, as it is saturated on that front besides other non-audio stuff is keeping me busy.

The next "upgrade" I am planning on is trying out KT150 output tubes in place of the KT120 that I have been using for the last six months or more. I briefly tried KT66 and also KT88 one evening in January. As expected there was loss in bass but also midrange and treble. I feel that the added bass with the KT120s carries/influences the higher frequencies in the air between the speaker and listener. There is a symbiotic relationship between all the audible and beyond audible frequencies: it seems they help each other out.

Cheers,
Bonny
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Re: ZMA - comperhensive upgrade complete
Reply #139 - 12/24/20 at 21:23:45
 
Finally glad to report the last upgrade that I had envisaged for this multi-year upgrade: KT150 power tubes, the highest wattage KTs available and the highest wattage tubes I can install on this ZMA.

These tubes are tall: 5 inches in height not including the pins.

Setting the bias to 95 mA seems to be the sweet spot in terms of musicality and transformer loading.

There is a lot of talk of Tungsol KT150s on various forums and none negative. I am glad to say that I concur.

The benefits of additional available headroom provided by the KT150s   over all the rest in the KT genre even the KT120s that I had before is immediately evident. All the positives mentioned all along in this thread earlier have improved.

I believe this ZMA is now is showing the true colors of the music that is being played on my 90dB speakers without rolling off the extreme frequencies at either end and playing it with unhindered aplomb wringing every nuances from the source. Details have surfaced, very subtle details but important to make the listening experience even more pleasurable.

Have a Merry Christmas folks.
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Re: ZMA - comperhensive upgrade complete
Reply #140 - 12/24/20 at 23:15:22
 
BAndrade, you are a Mad Scientist!   Grin
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Re: ZMA - comperhensive upgrade complete
Reply #141 - 12/25/20 at 00:45:08
 
Archie, I'll second that!
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Re: ZMA - comperhensive upgrade complete
Reply #142 - 01/05/21 at 02:15:43
 
Thank you Archie, Steve.

Scientist not, mad yes. Lucky for me for this project I managed to channel my Obsessive Compulsives tendencies to good effect. 50% percent of the time for other projects I wasted a lot of money.

In a sense this was an easy project because of the fantastic base product that the ZMA is by itself. In the final analysis I just scaled it up in input and output power and like of like parts that cost more with only some minor tweaks.

This was money well spent starting with purchasing this amp and then the mods for it has always been and continued to be more and more a mood altering listening experience every time.
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Re: ZMA - comperhensive upgrade complete
Reply #143 - 01/05/21 at 06:52:21
 
Due to a recent experience I'm wondering about heat input into the top plate from the power tubes.  I actually melted the plastic scales on my meters -- don't ask!  lol  I assume the KT 150s put out a lot more heat.  Are you seeing any adverse affects?  Or maybe they don't?
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Re: ZMA - comperhensive upgrade complete
Reply #144 - 01/09/21 at 13:55:50
 
Bandrade,
I enjoyed the read. Although not as theoretically trained as you, your simple logical approach parallels mine.

Makes good sense dollars shillings and pence is what came to mind over the read. Roger Walters rambled those words in his "Amused to Death" work.

Thanks!
John
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Re: ZMA - comprehensive upgrade complete
Reply #145 - 01/16/21 at 01:34:49
 
Sorry for the late reply.

No heat related issues. The meters, the top plate, the nearby capacitors and output transformers are as good as new.

Speaking of heat and the related current draw. I am still not using a fuse but a 8mm dia. 7N copper wire mentioned before. Having tasted the pill, simple can't go back. It's a risky proposition with the wire. One day when a tube decides to internally short I am in trouble. But I am enjoying the music so much that I am not even thinking of it.

The initial inrush current draw is between 14 to 15 amps which settles to 9 amps after all the capacitors charge to some extent in about 5 minutes. Remember my power circuit has about 30,000 uF of capacitance besides the large inductance from the larger input and output transformers. This may be wishful thinking but the fuse rating that I would need is so close (within 3A) to my 20A circuit breaker at the electrical panel that the CB should work about as fast considering the I would need a slow blow fuse.
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Re: ZMA - comperhensive upgrade complete
Reply #146 - 01/16/21 at 01:40:53
 
Thank you John.
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Re: ZMA - comperhensive upgrade complete
Reply #147 - 01/16/21 at 06:38:43
 
Did you type that wrong or am I just misunderstanding?  If your ZMA is drawing 9 amps, that's about 1100W.  I think the stock ZMA draws 150W.  Is that possible?
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Re: ZMA - comperhensive upgrade complete
Reply #148 - 01/16/21 at 10:26:52
 
Placing large capacitance in close quarters with coils can create increased draw of power. It happened in my scheme of power conditioning by placing 5 banks or 4 10uf capacitors inside a case with a large transformer wired for balanced power. This increased the power draw by 8 amps on a system that normally draws 6. Installing the capacitor banks outside the case returned all to normal.
I can only conclude that the flux from the coil intermingles with the capacitors inductance creating a controlled short circuit.
John
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Re: ZMA - comperhensive upgrade complete
Reply #149 - 01/16/21 at 14:17:20
 
I suspect the stock ZMA draws about 4 amps after settling down. When mine was stock before the mods, I needed at that time to install at least a 7 amp fuse in it. Anything below would blow during start up even though the recommended fuse was 6.3 A.

As is well known the ZMA being a Class A amp is very in-efficient w.r.t power consumption. Being a push pull amp helps a bit in this regard but is still very in-efficient. The benefit is the simplicity in design resulting in awesomeness in terms of sound production and fidelity to the original music.

Regarding the modified ZMA. Around 9 amps is correctly typed. Most likely the caps are not yet fully charged yet at the 5 minute point because they are also discharging a significant amount in powering the amp at the same time so still drawing more current than steady state current. Besides the massive amount of capacitors I also have large chokes in the power filtering circuit.

It takes about 30 minutes for this ZMA to start sounding its pristine best possibly the caps are fully charged by then and reach an equilibrium between the charge/discharge rate. I usually have to lower the volume after 30 – 40 minutes as the volume goes up with time. After I toggle the power switch off all the tubes still glow fully for about 10s solely powered by the caps before they flicker and turn off.
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