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
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.
clio09
3,345 posts
 
This is a bit of a curiosity for me. If the output of a DAC is 1.5V, is there a minimum input impedance the preamp should have to accomodate the DACs output? Does the preamps gain play into this equation? My preamp has 4 gain settings, 11db, 14db, 17db, and 20db. I have always used the preamp with the 11db setting, but since I am now using the Rothwell attenuators it would appear that only 1bd of gain is getting passed into the amp. That seems pretty low to me. It's been suggested by others to go to a passive, but I researched this and don't want to risk giving anything up in dynamics. The preamp is a Joule Electra LA-100 MkIII (20k input impedance, 300 ohn output impedance).
dacostab
84 posts
 
If your AI preamp is out of warranty and you have the schematics, you can probably get a good tech (if you know one) to change a couple of resistors on the premap attentuation board....come to think of it, AI should do this for you at a very low cost.
downunder
1,329 posts
 
Endler attenuators r the best and easily crap on the Rothwell's. I have both and the Endlers are transparent and flexible as you can set the exact attenuation you need.

Go for these. BTW, just a happy customer

http://mysite.verizon.net/vze4c5pt/id2.html
restock
831 posts
 
I have similar problems: A tube preamp with 23 db gain, a fairly high output CDP with 2.3V, a very sensitive amp. Overall this results in about 10db too much gain.

As for solutions:I also read about mixed results with the Rothwell attenuators and therefore ended up looking at the following attenuators:

- Endlers variable stepped attenuators
- EVS fixed volume attenuators

Overall the EVS seem like the best solution. Another alternative of course is to go completely passive.

Rene
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