2. amps-preamps
  3. 1137965724

CD output voltage too high for preamp: what to do?

I have an Audible Illusions preamp which is designed for a 1.5v input signal. I am told that this is standard. My Ayre CX-7e puts out 2.25v. They play beautifully together but I have too little control over volume: I cannot use the preamp vol controls beyond 9 o'clock because it is way too loud. Likewise it is hard to get just the right volume in the limited range available. This is worse with some CDs for reasons I do not know.
Audible Illusions will change the preamp attenuation board for $275, but before I do so I wonder how others have dealt with the problem of newer CD players with higher outputs than their preamps were designed for.
gmargo
tvad
9,467 posts
 
I've recently done some research into attenuation for the same reason you describe. User reports of the Rothwell attenuators were mixed, with some users reporting added noise in the system. I decided to have my preamp's output gain adjusted even though it's more expensive, since this is the only way to remain true to the sonics of the preamp (and CD player).
kr4's avatar
kr4
3,424 posts
 
BTW, 2V (at 0dB level) is the output standard for CD players although, as you already know, it is often ignored. In crude A/B tests, the louder player will always sound more impressive.

That said, another major factor in your problem is the input sensitivity of the power amp which may be a bit high as well. After all, 2.25V is only 6dB more than 1.5 and should be within the ambit of the volume adjustment.

Kal
tvad
9,467 posts
 
I should add that the reason for my gain issue is the high 35dB input gain of my amplifier.
clio09
2,978 posts
 
I have a similar situation with a high gain amp (.8v for full output, 30 db gain) and was having the same issue with the volume control, both for digital (1.5v) and analog playback. I just bought the Rothwell attenuators and they work for me. Now I can go to about 12 o'clock before the level begins to get too loud (previously between 9 and 10 was the norm). I don't notice additional noise and used on the inputs of the amp I've lowered the gain from the preamp about 10db. Since this seems to be an issue with the CDP, I would first try these on the CD input of the preamp so as not to interfere with an other sources you may be using.
eldartford
4,262 posts
 
The fancy term "Attenuator" disguises the fact that we are talking about a couple of resistors. It's just a voltage divider. I would simply build it into the input jacks of the preamp. Do it with ordinary resistors, and when you get the volume right you can replace them with "audiophile" resistors if that makes you feel good.
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