Beefy Posted December 2, 2008 Report Posted December 2, 2008 It is probably fairly lame by most standards here, but there is an interesting article on PC audio that has just been published on my favourite PC tech site, Anandtech. It particularly caught my eye in that the test involved a Twisted Pair Opus in dual mono config......
fordgtlover Posted December 2, 2008 Report Posted December 2, 2008 The part I picked up on was the following statement. I wonder if others feel the same about the Opus DAC. The Opus's strengths are in its spatial presentation and rendering of distance between instruments. The tubes do add a touch of warmth to the presentation, which is probably needed as this DAC pretty much strips everything from a recording and throws it into the soundscape. It's great if you've got a high quality recording, but on discs that have been butchered by recording engineers or those containing low quality digital samples the presentation is ruthless.
Beefy Posted December 2, 2008 Author Report Posted December 2, 2008 The part I picked up on was the following statement. I wonder if others feel the same about the Opus DAC. ...It's great if you've got a high quality recording, but on discs that have been butchered by recording engineers or those containing low quality digital samples the presentation is ruthless. Most here would think that about the majority of high-end DACs, wouldn't they? 'Source first' does start at the recording after all...... But even then, I can't quite work out from the article how he's got it hooked up. He mentions the Ballsie in pg5, para 2, but then proceeds to say 'audio output feeds into a 3A5 dual triode per channel' suggesting he uses outputs straight from the DAC. If this is the case, he might get different results by including a dedicated filter and line stage between the DAC and the amp.
fordgtlover Posted December 2, 2008 Report Posted December 2, 2008 Most here would think that about the majority of high-end DACs, wouldn't they? 'Source first' does start at the recording after all...... But even then, I can't quite work out from the article how he's got it hooked up. He mentions the Ballsie in pg5, para 2, but then proceeds to say 'audio output feeds into a 3A5 dual triode per channel' suggesting he uses outputs straight from the DAC. If this is the case, he might get different results by including a dedicated filter and line stage between the DAC and the amp. Sure, the source first mantra requires pristine material, but much of the music I like is simply not available as high quality recordings. As a result, I need kit that is sympathetic to source deficiencies. I couldn't think of anything worse than buying gear that exposed so many flaws that I ended up hating my music. I have been toying with the idea of buying an OPUS DAC, but if its presentation is ruthlessly revealing, it just wouldn't work out for me. Perhaps I've been hiding under a rock or something, but I haven't seen too many really useful reviews of the Twisted Pear DACs.
Fungi Posted December 2, 2008 Report Posted December 2, 2008 No, there definitely are less reviews for DIY goodies in general.
Beefy Posted December 2, 2008 Author Report Posted December 2, 2008 I couldn't think of anything worse than buying gear that exposed so many flaws that I ended up hating my music. Yes, I see your point \ On the flipside, even an iPod and ESW9 reveals the recording deficiency of much of my music. I was listening to Breed Obsession by Gyroscope today, and there was an insane amount of clipping. You might expect that from a WA rock band, but even so...... Perhaps I've been hiding under a rock or something, but I haven't seen too many really useful reviews of the Twisted Pear DACs. There are very few that I have seen, unfortunately. Dare I say that most DIY'ers don't just give out equipment to shills masquerading as reviewers. I would love to do a 'proper' review of my Buffalo, but I don't have a high end source for comparison, or appropriate phones to really do such a review justice. Not to mention the fact that I'm pretty sure my hearing sucks arse, and my brain is extremely pliable to expectation. My lady friend barely tolerates this hobby as it is - I doubt she would help me out with double blind tests!
Dusty Chalk Posted December 2, 2008 Report Posted December 2, 2008 Most here would think that about the majority of high-end DACs, wouldn't they? 'Source first' does start at the recording after all......No, absolutely not. I find even harsh recordings to be more listenable on the best systems. It could quite possibly be that classic tube distortion -- second order harmonics, is it? -- or it could just be because it doesn't make it worse, but yeah. I listen to comressed distorted digititis-laden crap all the time.
dsavitsk Posted December 2, 2008 Report Posted December 2, 2008 The tubes do add a touch of warmth to the presentation Tubes do not "add warmth". Tubes are very linear devices -- much more so than transistors. The most likely culprit of the "added warmth" in many tube circuits are the multiple capacitors in the signal path, which do add warmth and distortion in spades. These can be designed out in many cases, but doing so is exceedingly rare. I've almost never seen it done in commercial gear. Also, the 2nd harmonic distortion thing is a dumb myth. If you want to convince yourself of this, use your computer to add 2nd harmonic distortion while you listen. It will not make your solid state gear sound like tube gear. It will make your solid state gear sound like solid state gear with a high 2nd harmonic component. Tube gear often sounds good in spite of the 2nd harmonic distortion, not because of it.
fordgtlover Posted December 3, 2008 Report Posted December 3, 2008 Tubes do not "add warmth". Tubes are very linear devices -- much more so than transistors. The most likely culprit of the "added warmth" in many tube circuits are the multiple capacitors in the signal path, which do add warmth and distortion in spades. These can be designed out in many cases, but doing so is exceedingly rare. I've almost never seen it done in commercial gear. Also, the 2nd harmonic distortion thing is a dumb myth. If you want to convince yourself of this, use your computer to add 2nd harmonic distortion while you listen. It will not make your solid state gear sound like tube gear. It will make your solid state gear sound like solid state gear with a high 2nd harmonic component. Tube gear often sounds good in spite of the 2nd harmonic distortion, not because of it. Thanks for the information. Just to confirm, the comment about tube warmth was quoted from the article. It was not my comment.
Dusty Chalk Posted December 3, 2008 Report Posted December 3, 2008 I, on the other hand, was regurgitating a theory that I had heard to explain my experiences. It could well be the caps, I don't know.
fordgtlover Posted December 3, 2008 Report Posted December 3, 2008 Has anyone heard the OPUS DAC with poor recordings. Is the presentation 'ruthless'?
dsavitsk Posted December 3, 2008 Report Posted December 3, 2008 Just to confirm, the comment about tube warmth was quoted from the article. It was not my comment. Sorry I didn't quote that very well. I was attacking the article, not the messenger. I, on the other hand, was regurgitating a theory that I had heard to explain my experiences. It could well be the caps, I don't know. The increased 2nd harmonic theory is stated over and over and has come to be accepted as truth. But, as I say, there really isn't any good evidence that it's true, and indeed, there are lots of reasons to think it is false. The cap theory is mine, and my experience seems to be that if you get the caps out of a circuit, you lose that sheen and bloat, but it could certainly be something else, too. -d
justin Posted December 3, 2008 Report Posted December 3, 2008 I would think the high output impedance of OTL tube amps would be the biggest reason
fordgtlover Posted December 4, 2008 Report Posted December 4, 2008 Sorry I didn't quote that very well. I was attacking the article, not the messenger. snip...
fordgtlover Posted December 4, 2008 Report Posted December 4, 2008 Sorry I didn't quote that very well. I was attacking the article, not the messenger. snip...
Beefy Posted December 4, 2008 Author Report Posted December 4, 2008 I would think the high output impedance of OTL tube amps would be the biggest reason Just curious...... how high would we be talking for a 'standard' design?
dsavitsk Posted December 4, 2008 Report Posted December 4, 2008 Just curious...... how high would we be talking for a 'standard' design? Output impedance for a cathode follower is approximately ra/mu, or 1/Gm. For the standard 6080 used in a headphone amp, this is about 150 ohms (the reason they work at all is because there is a ton of current -- here's a good article on this). Less than warmth, this high Z out really just leads to flabby bass and lack of control for Low Z phones. OTL does often have warmth, but note the 3 signal path caps (output, interstage, and Rk bypass for the driver) in the standard design, plus the several PS caps that are also in the current loop.
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