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In Reply to: RE: Audio Note vs. Bottlehead vs. what? posted by PranaBindu on January 26, 2015 at 14:53:51
I've heard both Bottlehead and AN gear, and think both sound great. My Bottlehead Crack is a delight.
You mention needing an attenuator between pre and amp to minimize microphonics and make the volume pot usable. I think neither will be the case. Attenuators will never reduce microphonics; once a tube has picked up and amplified physical vibrations, the damage is done, and reducing volume reduces the signal along with the microphonics. If the gain-staging is way off making the volume pot hard to use, then you have a problem with gain-staging, not the pot. Actually, I doubt that would be the case, particularly if you run the VTL in triode mode. (It should also be pretty easy to add a resistor after the wiper on the volume pot to give you more usable range on the volume knob.)
I haven't build any AN kits, but the Bottlehead instructions are the best I've ever seen, and Doc Schmalle & company are really great to work with.
Cheers,
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
Follow Ups:
If the microphonics (or other low-level noises) occur upstream of the attenuator, they will be attenuated. This is the case with a noisy preamp followed by an attenuator at the input of the power amp.
I've never been able to condense the situation into a comprehensible forum post. I did however make a white paper on the subject. It's more than most people want, but it's here if you are interested.
Yes, an attenuator will reduce upstream noise by the same amount that it reduces the (upstream) program level. So, if you hear preamp noise when listening at about an 82dB SPL, attenuating the signal after the preamp will reduce both noise and program. It might be the case that, by the time you're at 72dB, the noise is no longer intrusive, and the lower SPL should reduce the distortion caused by microphonic tubes, if that was part of the problem. I don't see how an attenuator between the preamp and power amp can reduce the level of upstream-induced noise relative to program level without paying the price of listening at a significantly lower level. Am I missing something here?
Paul, I read you paper, and have a couple questions:
1) What is it you accomplish with that process? Is it to have the preamp operating at a level where it has the greatest non-distorting S/N ratio, or is it something else?
2) You write, "Sources should adhere to the -10dB(v) nominal standard, which can be accomplished in the source device, or at the input of the target device (preamp, usually). This is relatively easy. Amplifier/speaker combinations should produce 82dB sound level at the listener’s ear when the input level is -10dB(v). Unfortunately, it is extremely common to find there is too much gain in this part of the chain." Why is it important to hit 82dB at -10dB(v)?
Thanks,
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
Thanks much!
As I understand it, the attenuator is meant to address the gain-staging issue. I probably used the term "microphonics" incorrectly.
You wouldn't happen to remember any specific differences between the Bottlehead gear and the AN gear would you? I got a chance to hear an Ongaku driving DeVore Fidelity O/96's a few weeks ago. Amazing, but I'm sure that's the worst AN device to use as a referent for this decision.
I'm very much looking forward to assembling a preamp myself. I hope I learn a bit about such devices in the process.
Thanks again.
May the bridges we burn light our way....
I just point out again that Audio Note Kits is not the same as Audio Note (You can't compare anything about AN Kits to an Ongaku), and AN Japan is not the same as AN UK. The kit stuff is often on display at audio shows each year. Go on the AN Kit site and ask Brian when the next opportunity is to audition it, or maybe you can find someone on this thread who can let you audition. I think at the end of the day, that's the best appraoch. On the other hand, AN Kit stuff comes up on Audiogon a lot, so there is a market for it. Buy the kit, if you don't like it, resell it.
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