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NEW DECWARE AMP at DECFEST2007 (Read 28404 times)
Randy in Caintuck
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Re: NEW DECWARE AMP at DECFEST2007
Reply #45 - 09/07/07 at 19:41:28
 
Howdy Dave,

I think you should quit beating around the bush and just make your point .....  ;)

But, seriously, I think it is probably a design choice.  From the discussions I have had with Steve and a couple of other well respected amplifier designers it seems that there is no "perfect" iron.  Larger iron has its advantages and smaller iron does as well.  The final signature of the amplifier will be largely determined by the size of the OPTs ..... and Steve has made his preference a part of the design.

Of course, if I'm wrong about this, I'm sure that Steve will kindly correct me .....  :-?

Have a good weekend,

Randy
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« Last Edit: 09/07/07 at 19:49:27 by Randy in Caintuck »  

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selmerdave
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Re: NEW DECWARE AMP at DECFEST2007
Reply #46 - 09/07/07 at 21:37:25
 
I think you're probably right.  It just seems that conventional wisdom is that OPT's are the most important single part of a tube amp, any SET that I am aware of in the $1500+ price range includes some healthy-sized iron and that is often a selling point and price-justifier.  I also notice the Torii II has some big iron although I know PP and SET iron are fundamentally different.  Now as I pointed out in another thread, you for one dumped your other amps with bigger iron for your Select, and you aren't the only one around here that did that.  So I'm not necessarily going to have a hard time believing that there is a reason to choose the smaller iron, but given that Decware is virtually alone on it I would like to know why it's better than the bigger iron typically found on competitor's $2k amps.

Dave
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Steve Deckert
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Re: NEW DECWARE AMP at DECFEST2007
Reply #47 - 09/07/07 at 23:50:22
 
This is a great reservation to bring up because I'm sure most people share it.  Nevertheless it annoys me to no end.  Between 1993 and 1996 when I was developing the Zen amps guess what I worked on almost the entire 3 years?  Please don't think it took 3 years to figure out how to arrange 2 resistors and 1 coupling cap for the best sound...

Yes, output transformers.  The output transformers in all of our amplifiers are EVERY BIT THE QUALITY OF - IF NOT MORE SO than Electraprint or Sowter or Magnequest or Peerless, regardless of cost.  Talk to the gurus who design output transformers and they will tell you that the prices some of these BIG HIGH END trannys bring is insane.

We live in an ignorant world where bigger is always better.  I have 14 e-mails in today's inbox alone urging me to increase my penis size.

In the development of the Zen output transformers (which are clearly the biggest secret to their sound quality) I spent no less then 2000 hours winding, listening to and unwinding transformers.  

I was blessed along the way with a chance encounter by an 80 year old man who worked for Peerless. He was a friend of a friend of mine and that friend brought him over to my house because he thought the old guy would get a real kick out of my dedication to finding the best way to wind a transformer for sound quality. Indeed the gentlemen took a real liking to me and shared many of his deepest secrets which I took seriously. He was one of the designers of the then famous Peerless iron that Altec and others used in their amplifiers.

Interestingly enough your concerns about our small transformers were addressed in a paper I wrote years ago. The President of Peerless call me on the phone after reading it to let me know he had no idea what I was talking about when I say scramble wound. I explained it to him exactly as the old guy explained it to me.

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« Last Edit: 09/08/07 at 00:17:11 by Steve Deckert »  
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Steve Deckert
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Re: NEW DECWARE AMP at DECFEST2007
Reply #48 - 09/07/07 at 23:52:53
 
Here is the paper for those who don't like to read the articles section of the site:

The secret behind the Zen Triode output transformers is that they are patterned after the older Peerless iron that was hand-scramble-wound for ultra wide bandwidth and flat response. If you are familiar with the any of the all time great vintage tube amps you already know the Peerless output transformers were a large factor.

Our transformers are also hand scramble wound using a winding topology that evolved from several prototypes.  The air-gapped cores are made from top grade USA made grain- oriented-silicon-steel - the heart of any transformer.  The better the core the less of it you need and the lower the saturation.  In contrast transformers made in China do not have the same quality steel and suffer as a result.

Add to that the fact that I choose to locate them on a different plane than the power transformer and at the opposite end of the amp where no field is present.  Instead of using end-bells the chassis is used to shield it- making the transformers appear about 1/2 the size they actually are.

I also choose a single 6 ohm tap because I found the single tap prototypes sounded better than the multi-taps, something about the unused taps.  The primary impedance is 9800 ohms with 2850 winds.  This makes the el84 and SV83 tubes couple more power as the speaker impedance drops.  Max power is at 2 ohms.

If you measure the current and voltage on an SE84C Zen Triode Amp with a 1KHZ sign at 2 volts you will find the current output actually exceeds the voltage.

Many people think transformers have to be huge to be good, but its all in the quality of the steel.

Another rather unique feature of our output transformers is that they float.  They have no reference to ground.  This is difficult to do in all but the most stable amplifier circuits.
Now there is a big fuss is over COBALT transformers

There is no evidence that "cobalt" transformer will sound better than our transformers in a Zen Triode Amp.  What it has going for it is a catchy name, high cost, low availability, and it's the hot topic over in Magnaquest/Bottlehead land.  I'm sure it's good, as is nickel, but after reading all the chit chat about it on the Internet I recognize that it's being largely overblown.  The majority if not all are done without air-gaps necessitating a para feed design.  We went through all that three years ago and concluded that para feed does not sound better to our ears.  It does however perform better which brings us down to the brass tacks of building amps that excel in performance (ie. para feed, constant current, etc.) or simpler "zen" like designs that to our ears sound better (but perform worse).  Take your choice.

The main advantages that nickel has over steel is less saturation.  There are two ways to deal with saturation.  A) use nickel or "cobalt", or B) just size the damn things 3 times bigger than they need to be so they don't saturate.  Our transformers do not saturate until somewhere between 15 and 20 watts.  Now depending on the amp we build, that is between 3 and 10 times over sized.  You can be sure that if someone is using expensive core materials like nickel or cobalt they aren't likely to oversize the transformers.

Many engineers will point out that transformers in general induce distortions and therefore not using one is better than using one.  Output transformer less amps (tube) are often great sounding amplifiers, however they are also finicky about speakers and have many other disadvantages.  We feel the transformer is a major key to why most people think tube amps sound better than solid state.  The transformer couples the output stage to the hostile impedance of the loudspeaker in a synergistic way not possible without one.

The common way of doing things in the high power high-end audio world is to build high power amplifiers with high dampening ratios so that they will better control the speaker and be less effected by the feedback voltage generated by it.  On the other end are speakers with high power ratings, low efficiency and complex crossovers that attempt to show the amp a less hostile impedance curve.  Basically put, amps that are less effected by (can't feel) the speakers, and speakers that are less effected by (can't feel) the amps.  

In a great high fidelity tube system the output transformer makes the speaker aware of the amp, and the amp aware of the speaker.  The two work together, reacting to each other with any given passage of music.  This is call synergy.  It is made possible by output transformers.  The best vintage solid state amps I've heard from the 60's and 70's used output transformers.
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« Last Edit: 09/07/07 at 23:57:29 by Steve Deckert »  
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Steve Deckert
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Re: NEW DECWARE AMP at DECFEST2007
Reply #49 - 09/08/07 at 00:23:47
 
And yes, you're right - that answers the OPT question.  If there were something clearly superior to a Zen OPT I would have used it in these monos.  There isn't.

Steve Deckert

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Lon
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Re: NEW DECWARE AMP at DECFEST2007
Reply #50 - 09/08/07 at 01:29:20
 
Okay. . . regarding the photo. . . .

SHWING!
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selmerdave
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Re: NEW DECWARE AMP at DECFEST2007
Reply #51 - 09/08/07 at 02:06:33
 
Yikes.

Steve, thanks for your reply, and sorry to annoy you.

Dave
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stevef
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Re: NEW DECWARE AMP at DECFEST2007
Reply #52 - 09/08/07 at 03:55:16
 
Since we have entered the area of OPTs,  I have a question.  Older audiophiles will remember the Carver silver seven tube amp.  Bob Carver built a sample to prove he could build a great tube amp.  Mike Kay at Lyric Audio encouraged production, and it was distributed.  Enough background.  I remember hearing a pair with rather poor loudspeakers, not much of a demo.  The unusual aspect of the amp was that each output had two OPTs, and I don't believe that they were identical.  My question is "Why two different paralleled trannies?''  I haven't seen this configuration anywhere else.

Steve
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Steve Deckert
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Re: NEW DECWARE AMP at DECFEST2007
Reply #53 - 09/08/07 at 05:42:23
 
Dave - you didn't annoy me at all.  IT annoys me.  You simply pointed out what most people would logically think and gave me an opportunity to address it.

SteveF - The original Torii used two separate transformers for each half of the push/pull but they were in series and matched.  To use two different size transformers in parallel would do a number of things... The saturation pattern on each core would be different... This could possibly protect the midrange from bass saturation letting you push the amp harder with less iron making a grand opportunity for cost savings.  It would also no doubt alter the signature of the amplifier in interesting ways in which case it may have been an attempt to create something rather special - similar to what i did with the original Torii.   It could have also not really been in parallel in which case you would double the number of primary taps which would allow you to wire it like a Macintosh for better damping.
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rayd
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Re: NEW DECWARE AMP at DECFEST2007
Reply #54 - 09/08/07 at 13:23:59
 
I see two inputs on each monoblock - I'm guessing one is for use with the pot and the other is direct (bypassing the pot)?

Also, couldn't find much on the OA3 tube on the internet. If it's used for voltage regulation, is there any tube-rolling advantages for this particular type?



- Ray
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Steve Deckert
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Re: NEW DECWARE AMP at DECFEST2007
Reply #55 - 09/08/07 at 14:11:18
 
Ray - No tube rolling with the OA3's required.  We spend a lot of time worrying about clean power and in these amps the B+ that feeds the input tube goes through the OA3 meaning that it jumps the gap between anode and cathode before it feeds the input stage.  Think of it as electrons traveling between the power supply and the input tube with NO WIRE.

Steve
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Hotsauce
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Re: NEW DECWARE AMP at DECFEST2007
Reply #56 - 09/08/07 at 14:30:22
 
If I'm understanding correctly then, the 0A3 is the tube eqivalent of a Zener diode.  

John C.

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Steve Deckert
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Re: NEW DECWARE AMP at DECFEST2007
Reply #57 - 09/09/07 at 01:58:23
 
An OA3 is the tube equivalent of a Zener diode, yes.   Except the OA3 looks WAY COOLER when it's on.
Steve
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« Last Edit: 09/09/07 at 02:00:32 by Steve Deckert »  
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Steve Deckert
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Re: NEW DECWARE AMP at DECFEST2007
Reply #58 - 09/11/07 at 02:55:53
 
And here is what it looks like in the alternate black zen base...  



Steve Smiley
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veryoldcat
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Re: NEW DECWARE AMP at DECFEST2007
Reply #59 - 09/11/07 at 06:26:47
 
What happened to the high and low bias position switch for the input valve on the new mono's? Angry

(I've never been a fan of the high bias position on the original se84cs. In fact, I hate the "amped" high bias sound on my Select, but prefer the more relaxed low bias position).

Karl
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