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Transformers, much more important than I ever knew (Read 1107 times)
SteveC
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Transformers, much more important than I ever knew
12/10/13 at 22:35:42
 
Before I found decware, I was reading about Susan Parkers Zeus mosfet amplifier.  simple design, no feedback, described sound is similar to the described sound of a zen.  I've always been interested in building one.  But to get the transformers, shipped from UK, costs 2 arms, several legs, and more.  I recently read her quote "the transformers are the heart of this amp" or something like that.

I know that the turns ratio of a transformer dictates how much AC voltage is stepped up or down, but I had no clue about bandwidth issues, and internal losses based on construction of the transformer.

So I searched. And found this page (I guess Lenard sells their own stuff, but there's a great deal of educational type pages at this site).

http://lenardaudio.com/education/14_valve_amps_5.html

It's a very interesting page if you want to understand your output transformer.  

I never really thought about the fact that all our musical information goes through the output transformer.  I mean, there's no electrical connection between the amplifier and the speakers.  It all goes through a magnetic field.  So the quality of that device really matters.

I didn't realize power transformers are made to operate at a single frequency (60hz). and so.. they act like higher frequency filters. So a triplite isolation transformer filters some line noise by virtue of the transformer wanting to pass only 60hz (well, whatever it's bandwidth is).

I didn't realize that output transformers are layered in complicated ways in order to get the widest bandwidth through them, on the high end.

And size and weight is the thing that limits the low frequency range because lower and lower frequencies will saturate an inadequately sized core.  There's a 60 lb experimental output transformer in the link.

I'm awe struck how much there is to know about OPT's.  I think this helps me understand the statement about the zen opts seasoning over time.  all the music is transferred by that magnetic field.  If anything about the iron core changes (metallurgical things) the field will change.  the sound will change.  season.  

thought I'd share. (some of you guys already know this stuff.)

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AiDee
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Re: Transformers, much more important than I ever knew
Reply #1 - 12/10/13 at 23:21:19
 
Good read thanks.
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Lord Soth
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Re: Transformers, much more important than I ever knew
Reply #2 - 12/11/13 at 01:56:53
 
Great article!

BTW, I always wondered why no one has ever offered super Cryoed versions of transformers?

Or maybe putting the entire little Zen amp (except the wooden base) through a CRYO processs?
I bet it would sound even sweeter.
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Lonely Raven
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Re: Transformers, much more important than I ever knew
Reply #3 - 12/11/13 at 02:52:35
 

Having built several guitar amps over the years, I had to learn a lot about power and output transformers. The Output transformer is hugely important to the sound of the amp. The type of metal, the way it's layered, the thickness of the layers, the amount of metal. Then there's the type of copper, the gauge, number of wraps. It causes my brain to melt out my ears - so I eventually I just pick one or two high end brands that are most recommended, and get the transformers that they recommend for whatever project I'm working on.

Looking at the Decware transformers on the current amps, you'll notice they are all heavy, with many thin laminates, and oversized. Even my 15 year old Zen amp, the power transformer is way overbuilt for an amp this size. Good quality stuff.
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stone_of_tone
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Re: Transformers, much more important than I ever knew
Reply #4 - 12/11/13 at 05:38:52
 
Even if you're not interested in the MA....the read is important. He truly is selling the Amp at an introductory price. I am glad I can afford one now.   

Re: The MYSTERY AMP !
Reply #96 - 07/12/13 at 02:32:52    

Transformers have the biggest effect on a tube amplifier's sound in my world, so it came as no surprise that this latest intrusion into the amplifiers voicing would be big. (No that's not true... it came as a big surprise!)  And now having just witnesses how different transformers effect the sound again, I still can't help but be amazed at just how much things can change!

After several evenings discussing the output winding topologies we recently tested some classic secondary arrangements with the typical taps against some dual secondary arrangements where windings of different lengths are combined on the same bobbin.  The differences ranged from something that sounded typically real good, to something that sounded magical.  Some interesting stuff since the only main difference is in the pattern of core saturation.  I expected to have to strain to hear the difference, but instead I had to check and see if we were still listening to the same amplifier.

With this rather pleasant discovery I now know this amp is going to be hugely successful.  Optimized for (but not limited to) KT66 output tubes, I'm currently witnessing it sound better than both the Zen Mono's and the TORII MK III.  That doesn't mean it is, because it's still to new and there is some infatuation that will need to wear off before I can actually hear it objectively.

I'll keep you posted as I put the fine polish on it and continue to wrap my head around it.  Right now my comment about the sound would be this:  Generally liquidity and honesty are rarely found in the same amplifier, but this seems to be a reference for both.  Almost too good to be true.  


Steve
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« Last Edit: 12/11/13 at 05:44:43 by stone_of_tone »  

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beowulf
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Re: Transformers, much more important than I ever knew
Reply #5 - 12/11/13 at 06:27:02
 
Since so much depends on the transformer, this begs the question ...

How is the sound affected by going OTL?  Would it be more neutral and have more accurate tone and detail to the original recording? Huh
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Lonely Raven
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Re: Transformers, much more important than I ever knew
Reply #6 - 12/11/13 at 12:47:31
 

Code:
How is the sound affected by going OTL?  Would it be more neutral and have more accurate tone and detail to the original recording? 



Transformers inherently cause distortion and some smearing - hearing an OTL amp nearly melted my brain with the amount of detail I was hearing.

At Steve's place, listening to the OTL amp was like someone turned on a 7.1 surround sound; except nothing had changed but the amp!

I'm glad he only gave me a sample of it, because I'd otherwise be hounding him to somehow make me one, and he said it was extremely expensive to make, used a ton of power, and was expensive to maintain tube wise. All of those "features" go against my better nature.
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beowulf
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Re: Transformers, much more important than I ever knew
Reply #7 - 12/12/13 at 06:12:27
 
Quote:
LR said,
Transformers inherently cause distortion and some smearing - hearing an OTL amp nearly melted my brain with the amount of detail I was hearing.

At Steve's place, listening to the OTL amp was like someone turned on a 7.1 surround sound; except nothing had changed but the amp!

I'm glad he only gave me a sample of it, because I'd otherwise be hounding him to somehow make me one, and he said it was extremely expensive to make, used a ton of power, and was expensive to maintain tube wise. All of those "features" go against my better nature.


This makes me realize how much time and effort goes into Steve's transformer designs to get the performance he does.

I'm just wondering why ... if OTL amps might be the purest form of delivery - why aren't there a lot more manufacturers doing it?

I know of very few designers making them such as Atma-Sphere and the kit you can buy from Transcendent Sound (their 300B OTL looks like a pretty fun project ~ $850 just in tubes though ... ouch!).
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« Last Edit: 12/12/13 at 06:13:02 by beowulf »  
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Lonely Raven
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Re: Transformers, much more important than I ever knew
Reply #8 - 12/12/13 at 14:53:50
 

It's all about impedance.

The whole reason we use transformers in the first place is because the circuit, the tubes, have a specific impedance, usually in the thousands I think - and our speakers have a completely different, much lower impedance. So the transformers are setup at a ratio - if the speakers are 4ohm, and the tubes are 4000 ohm, you need a transformer 1000:1 to get that tube to actually drive the speaker.

I believe there is also a danger of how much voltage an OTL puts out to the speakers...like dangerous to people.

So the first trick would be finding good sounding tubes that happen to have the right impedance to drive typical speakers. Some companies have found ways around that which is beyond me, and from the articles I've read it almost sounds like they aren't OTL anymore...but what do I know. After matching the impedance, it's all about building an amp around that tube, and doing it safely.
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Lord Soth
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Re: Transformers, much more important than I ever knew
Reply #9 - 12/13/13 at 07:37:41
 
As good as Atmasphere OTL amps were ( and still are), I saw a post from a Torii MK3 owner stating that he preferred the sound from the Decware amp. This is what piqued my initial interest in Decware Torii MK3/4 amps.

So I would not treat all OTL amps as "the" ultimate design, unless Steve D makes one! Wink

And after owning PP (Decware and non-Decware), SE amps in no particular order, the TORII MK4 has also convinced me that "SE" can still be beaten by a properly designed PP amp.

I also have no doubt that the Decware OTL amps will emerge as a viable commercial product one day......

Why?

The Tube Gods want us mortals to enjoy the music! Wink
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beowulf
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Re: Transformers, much more important than I ever knew
Reply #10 - 12/13/13 at 08:23:42
 
Quote:
Lord Soth said,
So I would not treat all OTL amps as "the" ultimate design, unless Steve D makes one!


LOL, yes I agree I would not think that either unless Steve puts one out Wink

I was curious though as to OTL by removing the tranny would lead to a more pure sound.  But when I look at the market there a very few manufacturers that I could call out that even make them, so it would lead me to believe that they are either (a) too complicated, (b) too expensive, (c) impractical/unreliable, (d) or they are not as great sounding as one would think and/or (e) all of the above. Huh
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« Last Edit: 12/13/13 at 08:29:16 by beowulf »  
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Lonely Raven
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Re: Transformers, much more important than I ever knew
Reply #11 - 12/13/13 at 14:39:23
 

After listening to Steve's OTL, I'm positive that a proper OTL amp sounds closer to the music than a traditional Transformer Output amp. They are really expensive, complicated, and for the most part impractical.

I don't recall if Atma-Sphere is one of the brands that seems like they sorta sidestepped the OTL with some different technology to make it work. They have patents on what they do, so I'm pretty sure it's not directly tube driven.

This is from their page, they talk about the transformer adjusting the voltage, but I think that's only part of it, as I was taught it's Impedance that makes the difference.

Quote:
Output TransformerLess
The acronym 'OTL' refers to a tube amplifier that is Output TransformerLess. Regular tube amplifiers have very high voltages in them and by contrast most loudspeakers are low voltage. In order to convert from the high voltage of tubes to the low voltage of a speaker an electronic device known as a transformer is used. Transformers are large arrangements of metal that also have large amounts of wire in them. The wire is arranged in two sets of WINDINGs on the metal of the transformer (called the CORE), so there is an input and an output. The input winding is called the PRIMARY winding and the output is called the SECONDARY winding. OTL amplifiers do not use a transformer, and sidestep many of the barriers to high fidelity reproduction that transformers cause (increased distortion, reduced bandwidth, plus the transformer absorbs power).

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maddog07
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Re: Transformers, much more important than I ever knew
Reply #12 - 12/27/13 at 19:29:49
 
OTL amps generally work best with speakers with higher impedances, like 8 ohms and above.. of which there are not many, and typically of high efficiency due to low power of OTL's - at least those with a reasonable number of paralleled output tubes.  They are inefficient, hot, have lots of tubes and thus are expensive to maintain.  Though most of the ones I've heard "bring the magic" more of the time than about anything else I've ever heard.  A popular OTL in the DIY world, that is affordable as OTL's go is from Transcendent Sound.  They will build them for you also for a fee, and they have "certified" builders associated with the co. around the country who will build the kits for you also I believe(they used to anyway).  
This company is practically in my backyard and I've known about them for years, but never owned "suitable" speakers until within the last year.  Now that I have the right kinds of speakers laying around and a Torii... a Transcendent OTL is on my bucket list also.....
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Lin
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Re: Transformers, much more important than I ever knew
Reply #13 - 12/27/13 at 19:41:49
 
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maddog07
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Re: Transformers, much more important than I ever knew
Reply #14 - 12/27/13 at 20:06:57
 
better keep an eye on this... Modjeski has made some mighty fine sounding amps over the years.. that did not follow commonly accepted norms for circuit design....
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Decware Torii MK3, Wyred4Sound DAC2, Theta Digital Miles, Emotiva UMC-1, Emotiva XPA-5, Aesthetix Calypso, Marsh P200b, Martin Logan Vista, Audio Nirvana 12" Alnico's, PS Audio PW P5, Goertz, Kimber, Nordost and DIY wires, PSA pwr cords, I'm outta room..
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