Audiophiletalk - Output Transformers on Tripath Amps

giorgino

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Output Transformers on Tripath Amps
Dec 15^th, 2009, 1:01pm

I remember reading about output transformers' role in determining a significant part of an amp's signature . I think Tim de Paravacini (EAR Yoshino) commented regarding making one of his SS amps sound tube-like and Steve Deckert wrote a paper on OTs. Has anyone ever put autoformers or OT in between a Tripath amp and speakers (Is it possible)? Were there any noticeable sonic changes?

I know, whilst good, Tripaths have never "done it" for Ed (nor me) and I'm just speculating whether this might move the sound closer to having "it".

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killabermudian Member Offline AudiophileTalk Rules! Posts: 23	Re: Output Transformers on Tripath Amps Reply #1 - Dec 16^th, 2009, 9:15am Hi Giorgino: A couple of years ago, I installed my zero impedance autoformers between my Altmann byob and Hornshoppe speakers and it sounded awful. Everytime I powered-up the byob there was a very loud pop coming out of the speakers. Autoformers were removed soon after. Bill
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giorgino

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Re: Output Transformers on Tripath Amps
Reply #2 - Dec 16^th, 2009, 6:49pm

Thanks for that Bill. That's very interesting. That's why I asked. I didn't want to go to the trouble of buying some output transformers just to find out it doesn't work.

I managed to destroy both of my Hornshoppe drivers with a power surge (pop) from my Tripath (10W) amp. This was from from switching off my AckDack. Ed said that it would not have happened from a tube amp with an OT. Weird.

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Ed

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Re: Output Transformers on Tripath Amps
Reply #3 - Dec 17^th, 2009, 7:22am

Hey George,
I probably said "with a tube amp". Your TPath most likely spit out a good amount of DC from the spike/pop. This is not possible with any tube amp, transformer or not (OTL types) as far as I know. It is likely to happen with transistor amps, especially DC coupled ones like an X 150.

You should hear the pops I have made with the Classe' Seven Hundred! I am getting to LOVE this amp. The Truth does too....it is silky smooth, not tube like, much better. Just as delicate but the headroom is crazy. At any volume from a whisper to an ear melting it is "delicate".

It was not like this with my previous pre amp. It was exactly what you'd imagine it would be!

I can't even stand to listen to Guy's F1 with The Truth. Every time I have cut it on I find myself scheming on how to get one! Can't afford it right now, but m@n is it sweet. The F1 has always been a fine sounding amp....with The Truth it finally got a pre as good as it is. It sounds like what you wish tubes sound like........no, not as good as the GM70. But close, with the same weird openness.

Oops......got carried away!

Ed

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Designing a loudspeaker is very easy, building one that actually sounds good is much harder.

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giorgino

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Re: Output Transformers on Tripath Amps
Reply #4 - Dec 17^th, 2009, 8:32pm

Hi Ed

You're probably right. I can't quite remember what you said, but it had "tubes" in it. Grin

So let's say if an OT sits on the outputs of a T-amp, would the Fostex still burn out? Any thoughts on the sonic effects of OT on speakers and T amps?

Okay re: The Truth. My system is sounding nice and we've spoken about my aversion to hassle and not wanting to move anything. I will have to send that cigarbox back to you in the new year. I'll want to have a preamp and it would be an interesting thing to try out. Can I have different box? (Not cigar or big casing!) Cheesy

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tea

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Re: Output Transformers on Tripath Amps
Reply #5 - Dec 17^th, 2009, 10:50pm

Hi George,

I have installed OTs in place of opamps in DACs for output stage for audiomagus (now defunct). I liked the sound, so contacted Bud Purvine (who made the OTs) with your question. I asked if he thought I could replace the output inductors on my KingRex Tripath with similar OTs. He thought it would be tricky as the OTs would be much larger than the inductors and he doubted it would significantly alter the sound (my primary goal). I did replace the stock inductors with hollow-core fine (40g silk-wrapped wire) inductors from autocostruire in Italy. Sound change was not great, but a bit more delicacy was the result. As for DC blocking, it would take 4 OTs as tripath amps will not allow shared polarities...You could mail Bud at: hpurvine@gmail.com for more info.

Richard

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trust, but verify

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giorgino Ex Member	Re: Output Transformers on Tripath Amps Reply #6 - Dec 21^st, 2009, 1:07pm Hi Richard - Thanks for checking it up for me. I was just curious as to the sonic effects of OTs on a T-amp. The Carina is sounding fine so I doubt I'd be sufficiently curious to go ahead with it.
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V-bro

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Re: Output Transformers on Tripath Amps
Reply #7 - Jan 9^th, 2010, 5:09pm

Hahahahhahahahaahhahahahahahahhahaha What a laugh! Grin

ehm.. sorry... Lips Sealed

Tea, transformers and inductors (even though they consist out of core material and copper wire) are really not the same thing. Also there are single ended, bridged and paralleled Tripath amplifiers, so you can't apply the same answer to all of them.

It's so sad really that most people preach like the know all about Tripath amplifiers while in fact know only the low powered ones (TA2021B, TA2024, TA2020)

There are such nice other Tripath amps with so much sweeter sound.
(TA3020, TK2050, probably also TDA2500)

The X150 is already 'old' by now working with TA0105. A chip replaced by Tripath back then by the TDA2500 for more reasons than just reliability. The X150 also has some other questionable parts, not to say bad, but certainly the air core output inductors are a questionable choice. But perhaps I'm wrong, haven't done extensive tests and measurements on that so far.

Output transformers on a Tripath amplifier, sure... BUT these amps are really designed for driving an impedance similar to a loudspeaker. By just connecting any transformer this is highly likely to give problems. Providing you connect something with a similar impedance and with an output impedance capable of driving speakers you may have something. Although I have many doubts like what it will do to the emission? I'm not at all worried about DC though, because although the inputs of Tripath amps may be DC coupled, the outputs certainly are not.

Maybe a simple test can provide some answers by using 100V line transformers. In this case I do mean two per channel, one to convert to 100V and one to convert it back again. Here you will provide a solution that will not pass through the switching frequency. But if it will be linear?..... Roll Eyes

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Ed

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Re: Output Transformers on Tripath Amps
Reply #8 - Jan 9^th, 2010, 6:01pm

V-bro,
The X150 I spoke of is the Pass Labs X150......it bears no resemblance to any "chip amp".

My post had to do with a dc coupled amp being able to kill a single driver speaker since there is no cap to block DC, if it receives a "thump".

I used the X150 as an example of how it can happen and guessed maybe that is what happened in his case.
http://www.passlabs.com/pdf/old%20product%20manuals/x150_om.pdf

Ed

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Designing a loudspeaker is very easy, building one that actually sounds good is much harder.

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V-bro

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Re: Output Transformers on Tripath Amps
Reply #9 - Jan 10^th, 2010, 5:35am

Ah, yes I'm sorry, the Passlabs X150! I have two of these amplifiers at my disposal, X150.5 to be precise. As can be seen here:
http://www.41hz.com/forums/showthread.php?2109-Clash-of-some-Titans/page3

I actually have two of them, one still works and the other one is broken on one channel. The one with the broken channel literally died of it's own heat. The current limiting resistors are fried and some caps dried out. Still working on the repair. They are expensive amplifiers which can't compete (IMHO) to a modern chip amplifier like Truepath. Expensive not only in the sense of the hardware, also the idle power of 200Watts isn't really what I'd call "up to date".

The thump can kill speakers indeed, even with a DC blocking cap. Usually choosing the value for this cap is a compromise between good DC blocking and good low frequency response. Choosing for the latter makes it a large cap which during the charging can still output DC for a second and can still kill certain speakers. The best way to solve such a thing is to use a speaker relay providing a turn on delay.

I used to build tube amps in the past and back then curse any chip amplifier believe me! I also used to work for a hifi shop and install half a million dollar purchases with Mark Levinson amplifiers and B&W or Avalon speakers. I know what sound I like at least... And I have been convinced about the new chip amps/ class D amps like the ones from Phillips (UCD) and Tripath. The latter being MUCH more magical and subtle in my opinion.

But, I'm drifting off topic here...

I have given the OT on a Tripath some more thought and do see some possibilities there... Providing you use the right transformer (so not just a tube amplifier output transformer) which provides the right impedance towards the amp and speakers. The switching frequencies will probably be killed sufficiently in the transformer. It was probably a more "expensive" and bulky solution which was not seen as practical by Tripath. I certainly think it can be done... And as with my electrostatic speakers the little turn on thump shouldn't have to kill the transformer... Cool

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giorgino

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Re: Output Transformers on Tripath Amps
Reply #10 - Jan 10^th, 2010, 11:31am

Thanks for the information V-bro. My query was two-fold but my initial curiosity was whether the introduction of transformers would modify the sound of digital amps so they sound more tube-like. While T-amps sound good out of the box, I've not been able to live with them long term. My guess is that no one's seen an advantage of such an idea and the extra cost involved would make it uneconomic.

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V-bro

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Re: Output Transformers on Tripath Amps
Reply #11 - Jan 10^th, 2010, 1:45pm

I wouldn't know what it will do to the sound.

T-amps tend to sound harsh, at least the 2x25W max. versions. Try a TK2050 amp, you'll REALLY like it!

Like I said I have built tube amps all my life until I discovered the potential of the T-amp in the Sonic Impact amplifier. I could not live with it long term because they broke down rather quickly (all three I had!) Then I tried an AMP32 from 41hz. After a while I got a bit tired of the sound and right now I have been listening to the AMP4 for the past two years and REALLY like it! It's like it is growing better and better.

This was after trying the Truepath, AMP5. AMP10, AMP9, AMP11, AMP7 and AMP15. I have to admit that in terms of noise, distortion and shear sound quality the AMP4 outperforms them all!

I still have a 300B single ended amp here, an EL34 push-pull and a hybrid JvdS amplifier which I regard as blurry noisy machines now, with no capability to neutrality whatsoever. A sax sounds like a car horn from the 300B amp, and there's not that much detail.....

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