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Preamp Noise with High-Efficiency Speakers

I have Avantgarde Duo Classic Speakers, I hear a very audible buzzing noise whenever I insert an analog preamp. If I run my DAC (AMR DP-777) directly into power amp, the noise disappears. I have tried 4 different preamps (tube and SS), 3 different amps, a bunch of RCA and XLR interconnects, the problem persists. I have tried dedicated power line and two power conditioners (with Multi-wave options) and various high-quality power cords, so far nothing works, and I am forced to run DAC-direct into power amp. The buzz is not very loud but certainly audible enough to be annoying. There's no noise running the same equipment and power source into regular speakers, I am pretty sure it's just the Avantgarde (104dB sensitivity). Please share your solution if you have had similar situations. Thanks!
yingtonggao
georgehifi's avatar
georgehifi
10,312 posts
 
Worth a try if it doesn't cost him even more money and time to rid the noise.
I believe he maybe just hearing the noise from too much amplification with 104db speakers and when he OMITS the active pre (and he has tried 4 different ones solid state and tube) he is reducing his overhaul system gain by maybe 40db or more, and this also equates to the reduction of the active component noise as well when he goes direct, remembering every 6db of added gain is double the voltage.

Cheers George
almarg's avatar
almarg
9,670 posts
 
... when he OMITS the active pre (and he has tried 4 different ones solid state and tube) he is reducing his overhaul system gain by maybe 40db or more...
George, note that he is talking about a line level signal from a DAC, not a phono level signal. I am not aware of any preamp that comes remotely close to providing 40 db of gain from its line level inputs, even with the volume control at max. Typical numbers these days are in the teens, or even less. And with a DAC or other digital source, commonly the volume control of an active preamp will be set such that its gain, from input to output, is less than zero in terms of db.

Bill (Grannyring), thanks for the acknowledgement. Glad I was helpful with that issue.

Regards,
-- Al
georgehifi's avatar
georgehifi
10,312 posts
 
Yes you are right Al, my bad, I was including the phono, but up to 20db for the line level is not unheard of.

eg:
The CAT line stage: 15.0dB of gain set to Low and 25.8dB set to High.
Balanced Audio Technology line preamplifier gain was slightly higher than the published specification, at 18.7dB

It only takes the OP's power amp 1.4v to clip and he has over 2v from the dac so he does not need and more gain from the output stage of a preamp which in 99.9% of cases comes after the volume pot.

Cheers George
atmasphere's avatar
atmasphere
12,426 posts
 
My comments on voodoo are just that some believe that an active preamp can actually add real musical information that the source isn't providing, this shatters me that some can believe this.

You won't get any argument out of me on this! I am of the opinion though that passives *loose* detail, not that actives *add* it...

I also agree that if you can get by will less gain, so much the better. So we do offer or preamps with no gain in the line stage, just our direct coupled tube output, which has no gain driven by the volume control.

However:

We have had pretty good luck with getting low noise without removing the gain stage in the preamp, even on speakers of that efficiency (we have customers using speakers that are 107db), which is why it is obvious that preamp gain is *not* the problem! **If it were, hiss would be the complaint, not buzz!**

I feel like I did not put enough emphasis on that last sentence but I don't want to yell :)
charles1dad's avatar
charles1dad
10,250 posts
 
Atmasphere wrote,"I am of the opinion though that passives loose detail and not that actives add it".Right! I`ve believe this for a long time. That`s why the common complaint concerning passive/direct connection is less,tonal body,weight,timbre and dynamic presence-drive.These are real musical attributes not colorations.
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