Case in point.
Can a Amp be "timeless" and compete with todays amps?
I’ve been into hi resolution audio for 20+ years, well longer than that but acquired high quality gear about that time. I veered off into other interests for 15 years but still had my system sitting idle in it’s dedicated room. I became interested in it again 6 months ago and began to update it. I still have my Rega Planar 25 table and a Dragon phono stage. I retained my CEC TL1 transport, but replaced my DAC with a Dinafrips Venus II, I also have the Hermes DDC which I feed my CEC into as well as my Cambridge Streamer. I sold my Genesis V speakers because they were having an issue with the left channel bass and since they were out of business I had no way to fix them, it was over my head. I found someone that wanted them and was willing to repair them himself. (he is very happy with them) I replaced them with some Goldenear Triton 1.r’s which I love. So here is the nostalgia part. I still have my VAC Cla 1 Mk II pre amp and my VAC Renaissance 70/70 Mk II amp. I feel they still hold up well sonically, so my thoughts are to send them both to VAC for the Mk III updates this fall of 2022, which includes replacing any necessary parts and "voicing" them back to new as intended when they were first made. I really believe these pieces are worthy of the restoration, are newer pieces today really going to make much headway? I cannot afford to replace these items with "like" items as I am retired and the discretionary income isn’t there anymore. I just feel like they are still really good and offer a very high quality sound. I mean 8- 300 B tubes can’t be all that bad can they? I’ve voiced the pre amp with with Telefunken 12AX7’s and I have a small stash of them. Tube sound is still great right?
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You're welcome. Irony is a must, in all things that are observed in moderation. Take..er.. your 'give and take', in it's norms. It's ambiguity, and shortness, for some, is designed from the ground up, to speak in ways of inflicted harm, via the least words possible. Trolling without seemingly being trolling. I see you. |
It has become an interesting thread. Two people are talking about negative feedback. One clearly understands the topic and appears to be able to talk about it in great length. The other appears to talk at great length. It is up to the reader to decide who is correct. I enjoy both, but for different reasons. |
I did not cover the aspect of trailing layers of various odd ordered harmonic distortion patterns, as I try to take care of that when I'm messing with an amplifier execution, at the fundamental level. It is a huge part of the coloration, as Ralph says. But so is the other aspect that I speak of. Have to be careful, though, or we'll be delving into some thing about big boxes on cables and an infinity of poles of articulation.😉 |
This statement is false. Its based on the idea that there is a time delay between input and output. What actually happens is there are frequency poles in the amplifier that cause phase shift; on an oscilloscope this appears as a time deviation if you are measuring in the range of the phase shift. Filter theory tells us that there will be phase shift at some high frequency (in an amplifier, the high frequency roll off will be on a 6dB per octave slop initially; this will impose phase shift to 1/10th the cutoff frequency). As you increase frequency, eventually the phase shift is so acute that the feedback becomes negative instead of positive, and the amp goes into oscillation. Norman Crowhurst was writing about this 65 years ago; none of this is controversial. When the amp goes into oscillation, it can be said that its phase margin has been exceeded. http://www.tubebooks.org/Books/crowhurst_basic_3.pdf (link above for those interested in how this really works) This explains what is really happening and is not some sort of pseudo neo-science. So if one has been paying attention, one should see what the problem is with feedback in traditional amplifiers (which includes all tube amps). You have an output transformer in most cases, and it causes a fair amount of phase shift, often inside the audio passband! As a result, it poses a limit on how much feedback can be used, and is a guarantee that the feedback will cause harshness and brightness as a result (I already explained why). Futterman applied 60dB of feedback in his OTLs, but the problem he was up against was not a lot different: his design not only had significant poles in the circuit design, but he also had overall insufficient Gain Bandwidth Product. This means that feedback was decreasing at higher frequencies and so harshness was the result. Because of the frequency poles oscillation was an ever-present danger as well. Bruno Putzeys wrote a wonderful article on feedback. https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf It explains much of what I’ve been talking about here in greater detail. Don’t worry if you can’t follow the math 😁 You’ll note that he mentions Peter Baxandall’s writings of how feedback imposes distortion of its own, reflecting Norman Crowhurst’s observations (and explanations) of that from 20 years earlier. Those individuals never got the chance to play with an amp with sufficient bandwidth and loop gain! Its precisely that (sufficient bandwidth and loop gain) which is why an older amp might not keep up with a state of the art design (although it might easily keep up with new amps that are rehashed circuits from earlier decades). |
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