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08/19/19 at 10:48:45 


       



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ZMA - comperhensive upgrade complete (Read 5669 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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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
Silver Cabling
DIY Isolation platforms under everything.
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BAndrade
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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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Archie
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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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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
Silver Cabling
DIY Isolation platforms under everything.
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BAndrade
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Posts: 114
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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BAndrade
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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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BAndrade
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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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