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Tube amp with cheap transformers 'useless' ?

post #1 of 106
Thread Starter 

Hi All,

 

     One of the things which consistently drives me back to SS is this : whether its for speakers or headphones, any tube amp under a certain price point (1500 USD seems to be thrown around with some regularity) is going to have (at least) one important drawback - the cheap transformer. I dont know diddly about electronics, but I do know you dont build a fast car around a lawnmower engine - carts notwithstanding. I read a lot about 'SET vs OTL' etc but its not clear to me whether one topology exempts designers from the need for a good transformer - am I reading too much into this ?

 

     Feedback most welcome. 

 

Thanks in advance

 

estreeter

post #2 of 106

Sounds about right to me, but the idea of cheap transformers being useless is more subjective I would say.  We live in an age where everyone's a DAC chipset snob when in fact the cost of the DAC chip is peanuts compared to everything else.  I'm no builder but from what I gather the transformer (and case-work) is typically a higher cost component in comparison to other parts of the build.

 

A few one-liners come to mind:

 

"You've got to pay to play"

"Buy nice or buy twice"

post #3 of 106
Quote:
Originally Posted by estreeter View Post

Hi All,

 

     One of the things which consistently drives me back to SS is this : whether its for speakers or headphones, any tube amp under a certain price point (1500 USD seems to be thrown around with some regularity) is going to have (at least) one important drawback - the cheap transformer. I dont know diddly about electronics, but I do know you dont build a fast car around a lawnmower engine - carts notwithstanding. I read a lot about 'SET vs OTL' etc but its not clear to me whether one topology exempts designers from the need for a good transformer - am I reading too much into this ?

 

     Feedback most welcome. 

 

Thanks in advance

 

estreeter

IMO if you read the parts list (Woo audio for example), you know what your getting. Like the WA3 isn't very expensive, but Woo Audio gives you a list of all parts. That away even the most picky audiophiles can decide if its cheaply made or not. Regardless, I have only owned SS amps, currently I have the Beyerdynamic A1 for my T1s. The pair have good synergy, but next upgrade will probably be a Liquid Fire or HeadAmp GS-1. I'll be auditioning the SPL Auditor and Corda series soon though, and I will post back here my impressions.

post #4 of 106

I know little about electronic but I believe smart design and clever solutions has a more profound effect on sound that the quality of the components used.

post #5 of 106
Quote:
Originally Posted by estreeter View Post

Hi All,

     One of the things which consistently drives me back to SS is this : whether its for speakers or headphones, any tube amp under a certain price point (1500 USD seems to be thrown around with some regularity) is going to have (at least) one important drawback - the cheap transformer. I dont know diddly about electronics, but I do know you dont build a fast car around a lawnmower engine - carts notwithstanding. I read a lot about 'SET vs OTL' etc but its not clear to me whether one topology exempts designers from the need for a good transformer - am I reading too much into this ?

     Feedback most welcome. 

Thanks in advance

estreeter

I'd say yes and no. OTL should remove the price and complexity needs fairly severely; the limitation being you usually don't see many inexpensive OTL designs that can drive low Z (high current) cans very well (if it all). The output transformer is usually what drives the price up anyways; even in DIY designs (ever priced out some of the Hammond models that are popular? Or ritzier manufacturers than Hammond? Egads!). Basically if you want lots of power, you need a transformer that can handle that (it should also be audio grade and so on) - and that gets expensive (the very paired down answer is that copper is expensive in large amounts). There's plenty of hybrid and inexpensive OTL units that spec out just fine, but the cheapest OTC I'm aware of is probably the WA6. And then look upwards from there.

There's also the typical boutique/mark-up concerns to be had. I'd have to agree with Sneis on this one.
post #6 of 106
Thread Starter 

Uncle Erik posted something similar to your comment re tube amps for cans that need high current a while back - I just find SS so much simpler all round.  

post #7 of 106
Simple is usually good - go with what makes sense.
post #8 of 106
Thread Starter 

Works for me - right up to the point where people start gushing about the latest tube amp and how organic and 'real' their music sounds. C'est La Vie

post #9 of 106
Thread Starter 

Interesting to read Transcendent's thoughts on their OTL designs, particularly the part about the sound signature not conforming to the usual expectation of tubey 'analog warmth' etc.

 

For my own future reference, this is one of the more concise summaries - 

 

http://www.atma-sphere.com/Resources/OTLs_Defined.php

 

I'm sure the SET camp would have a thing or two to say about some of that propaganda, but for a single page its all I need for now. 

post #10 of 106

Donald North of DNA has put up a few comments about his choice in transformers.  And others.

 

Maybe use his profile and search for posts by him to see what he says.

post #11 of 106
There is no doubt that in a transformer coupled design, the output transformer quality matters a lot. One of the things I think makes the Leben CS300 so special are the custom/in house designed and built transformers. It's also a significant reason for its cost.
post #12 of 106
Tubes are known as a waste of efficiency so you have to increase the power supply performance to account for it. Just building to spec and not oversizing will determine if an amp makes it or not. I am of the opinion that an amp is the power supply. The bigger/better the parts, the better the amp.
post #13 of 106
Thread Starter 

Thanks for the feedback, guys - I realise that I need a better title for this thread - it should be 'OTC vs OTL' to be clearer to others what I'm trying to get at. Its about more than just trying to find a tube amp that works with low-impedance dynamic cans from A-T, Grado etc - its about trying to avoid the usual 'Buy every sub-$500 tube amp that comes down the pike till I find one that works !' methodology employed by some on Head-Fi. If transformers cost money BUT thats the reality of getting good sound from a tube amp, better to go in knowing that upfront, non ? 

 

I've started spreadsheeting various amps so I can see, at a glance, which designs are OTL. Companies like Decware and Woo make a point of assuring prospective customers that the transformers in their SET designs are proprietary - obviously, they know we know how important the iron is to the overall sound. Decware do sell an OTL SET headamp/preamp, the CSP2+, but I havent seen .it mentioned on Head-Fi in months,  To be fair to Steve, he has enough on his hands with the Taboo and Mini-Torii back orders.

 

http://www.decware.com/newsite/CSP2.html 

 

And an old standby in budget tube amps, the Little Dot MKIV SE, is an OTL push-pull design. Seems to have plenty of fans here. 

 

http://www.littledot.net/forum/viewtopic.php?f=9&t=820

 

Some may think I am placing too much emphasis on the presence, or absence, of a transformer - they may be right, but my reasoning goes beyond an obsession with topology. If you live in a country which enjoys low Customs Duties and reasonable freight costs, the prospect of importing something like the WA22 may not seem too onerous. If you live in the US, you might have to pay some sort of State tax - Europe VAT etc, but in Thailand I will be faced with the prospect that every $100 of the purchase price will attract $37.50 in Customs and VAT. Add freight charges on the heavier OTC design and you are rapidly faced with an all-up cost of up to 150% of the purchase price. Suddenly paying ~$3000 for a $2000 amp doesn't seem like a good deal - ymmv. 

 

'What of local manufacture ?', I hear you cry - the irony is that these guys specialise in building output transformers in Thailand:

 

http://www.sacthailand.com/

 

A single headphone amp and a pair of statement monoblock speaker amps - all expensive in USD equivalents - it soon becomes clear that the iron costs money regardless of where you buy from. Yes, there are other tube amp builders in Thailand, but they would be faced with the same parts costs (complete with SAC's profit margin on top...) and you wont find any English language reviews of their products. Google Translate ? No thanks. 

 

My personal Cheap Charlie ways aside, the bigger question is obvious - is there anyone outside of the likes of Atma-Sphere ($$$) with the smarts to make OTL work, be it headphones or speakers ? I'll keep working on that spreadsheet.  wink.gif

 

(apologies for the length of this post, but I suspect I'm the only one still reading this thread by now anyway !  Cool  biggrin.gif)

post #14 of 106

For an OTL design to drive current into a low impedance 'phone would require several triodes or pentodes in parallel which does drive up the cost and complexity. If you want to drive low impedance phones and want to buy OTL to avoid the cost of good iron (or avoid cheap iron which can sound quite good if done right) you will need to avoid any OTL amp that doesn't have at least two high-power tubes in parallel per channel. Which will drive up the cost and put you back into the range of a transformer coupled amp anyway.blink.gif

 

With transformers you can change the impedance / drive voltage / current by turns ratio. With OTL you have to add tubes. Transformers DO have an effect on sound quality but there is a point of diminishing returns. Circuit topology and parts quality are just as important IMO.

post #15 of 106

I've heard the same. An OTC design will cost much more because audio output transformers are not (and should not be) cheap. A quality OTL can be much cheaper in comparison.

 

Correct me if I'm wrong, but I've heard that there are OTLs capable of handling low-impedance 'phones. The Zana Deux would be one of the few. I'm not sure how it's done, but something about the tube provides a low enough output impedance (12 Ohm they claim), so it doesn't need to be coupled to an output transformer for low-impedance 'phones.
 

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