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
YingtonggaoI am not sure the DP-777's output impedance (at more than 100 Ohm) and the FL-100's input impedance (57k Ohm) is a match made in heaven.Yingtonggao

100ohms into 57kohms
This is a great/perfect match end of story, especially that you have more than enough gain. And if you look at internals the DP-777 the volume control is not a tacked on potentiometer on the output rca's, it is a analog domain volume control that is after the dac yet before the tube output buffers. This will be the most transparent/perfect way you can get the signal from your dac to the FL100 amp. If then you don't like this, by all means colour it to your liking with a active preamp of your choice, this is why ALL active preamps sound different as they are not a strait wire with gain, as Nelson Pass alludes to in his statement. And if other can't see this they cannot see the forest through the trees and believe in voodoo.

Cheers George
But it should be noted that the passive preamp offered by Pass is no mere volume control. It is a buffer design that attempts to eliminate impedance issues that afflict many passive designs, IIRC.

I will also add my 2 cents:

Cent #1: I agree that attending to the gain structure of a system is a very important part of achieving system synergy. With speakers like the OP's, too much gain is likely to be an issue.

Cent #2: I have also never found a passive preamp that doesn't impact dynamics and oomph, compared to an active pre. Of course to get both the drive of an active and the level of detail of a passive you need to spend a good deal. So for some budgets you may need to choose one or the other. I found my perfect balance in the Musical Fidelity kW linestage.
My active voodoo sounds more like music. My voodoo ways confirm my active sounds more like the instruments sound live. Oh well, live music cast a spell on me causing me to enjoy great active, tube preamps!

Tried passives and George's LS on three different occasions! Purchasing the unit on two of those occasions..... Installed in passive friendly systems it was very good, but missing the cues that equate to the sound of live instruments and voice. Nice for sure, but the overall tone, natural weight and scale of music was simply absent. No voodoo at all, just reality to my ears.

Others will have a different experience and I say great! You're not a victim of voodoo, but just a different opinion and preference. Enjoy
Sorry Roscoeiii, you need to read Nelson Pass's quote more carefully.

"just an input selector and a volume control.Hardly any noise or distortion added by these simple passive parts"
His B1 buffer is active

"no worrying about what type of capacitors – just musical perfection."
His B1 buffer is also capacitor coupled.

Cheers George
Also just to let you know that Nelson Pass originally designed the B1 buffer back in May 2008
http://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-137.html#post1521766
to be on the output of the Lightspeed Attenuator so it could then drive low input impedance amps of 20kohms or less that some of his amps have that people want to use the Lightspeed with.
You can read all about it on the Lightspeed thread on diyaudio.
After that he released it in diy form with a passive pot for diyer's who wanted to use just a potentiometer as the volume control.

Cheers George