Preamp Noise with High-Efficiency Speakers

Thank you all for the very insightful suggestions. I'll do some experiment early next month. I will try removing the ground pin (on power cord) one by one, and then try a passive preamp to see if it's a gain issue. I've had a Benchmark DAC-1, even at 0DB setting (10 volt output on XLR!) it is dead quiet with the same pre/amp. Will report later.

Whart and Triode: I may have to go through the lengthy process like yours to eventually get rid of hum/noise. I was thinking about Granite Audio Ground Zero yesterday.

Georgelofi and Atmasphere: There are pluses and minuses using an active preamp, and endless threads/debate about going preamp-less. I am fully aware that in recent years digital front ends have better and better output stages capable of interfacing power amp directly; and before I fix everything I have to live with the AMR DP-777 driving my power amp (Audia Flight 100) directly. But you never know what you are missing, and I've witnessed many times a good active preamp can do wonders to a system.

Wow, I did not know my thread can attract so many responses in days! It looks like noise is more attractive than music.

Georgelofi, I currently do exactly what you say: set the input impedance at max (57k Ohm on RCA) and run DP-777 directly. I normally listen at -30 dB on my DP-777, so you are right, modern electronics have too much gain and we are throwing the signal away. And I have to either throw it away at DP-777's internal volume control, or at an external preamp. I don't know which way is better because the noise issue doesn't allow me to evaluate preamps.

I appreciate your (and Nelson Pass's) belief on the preamp-less approach, but I am not convinced that the volume control inside the DP-777 is a world beater; and I 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.

When I use conventional speakers (85-92 dB), having a good preamp is a clear winner. Audia's own Flight Pre actually worked much better than Cary SLP-05 due to impedance matching, and running AMR DP-777 direct sits somewhere between these two preamps. With a Cary V-12R power amp the results is totally reversed in favor of the Cary SLP-05.

I don't want to turn this thread into another arguement over preamp/preamp-less comparison, but we all know system matching is key and there's no way better than all others. At one point I bought an all Audia system (CD/Pre/Pwr), and an all Cary system to reduce the hassle of system matching. But at the end of the day it is still not simple. Now I am thinking about buying a Devialet D-Premier and sell everything else.

Cheers!

Atmasphere, you are right, I'd call it a buzz, not hiss.

Well, guys, this thread just gained another dimension.

I am a firm believer of well-designed active preamps after trying a few passive ones. I do not exclude the possibility of passives work better in other systems, and in return I hope the supporters of passives don't decribe all active preamps as "colored".

The noise I suffered may be related to too much gain, but I've heard systems with more active gain and with the volume pot(s) at maximum, when there's no music playing, the system is totally silent. Modern components easily achieve 100+ dB S/N ratio, two or three of them hooked up in serial should not generate such an audible noise.

Anyway, you guys reply faster than I could try different options. But this thread is very insightful.

After almost a month the buzz remains with any preamp, and luckily I can still enjoy music running source-direct. The buzz is audible both above and below 140 Hz, I know this because my Avantgarde Duo Classic speakers have active sub crossed over around 140 Hz, and I hear the buzz from both midrange horns AND the sub. I may be able to hear a little hizz close up to the tweeter horn, but it's much less intrusive, and "normal" for almost any speakers. The buzz is independent of the volume setting on the preamp, so it's not source-related. Tuning preamp volume all the way down doesn't diminish the buzz, turning preamp volume all the way up does add a little more noise, but when I listen I rarely go beyond 10 O'clock. I should mention that I did take some wires to connect the chasis of the pre and power amp (common grounding), nothing improves. I did not buy a Ground Zero.

Finally got a noise-free pre/pwr combo! Audio Mirror T-61 preamp + Cary 300SE monoblocks. I don't know why but this combo is free of noise/buzz/hiss. Sounds wonderful too! The best I've heard with Avantgarde Duo.

Substituting either pre or pwr with another brand and the noise comes back.

Unfortunately Cary discontinued the 300SE. Does anybody know the sonic difference between 300SE and 300SEI?

Yes, I did try preamp-less and preamped options between the DP-777 and Cary 300SE. I prefer the preamped sound, being more ripe, full-bodied, and solid. In comparison the preamp-less sounds a little cardboardy and less 3D, the difference is not as prominent as in some system though, but I consistantly find a good active preamp helpful in various systems (I've bought and sold hundreds on audiogon). Last night I invited a cellist friend to my home and we listened to various cello/string pieces, he confirmed that the preamped sound is closer to a real cello.

George, you are right the Cary is a low-gain amp and it certainly helps to reduce system noise in this case! But a good active preamp is the soul of a system and many people can't live without it. Nelson Pass has a point, but other designers at Conrad Johnson, Audio Research, Supratek, etc are not dumb either.

I should mention that Audio Mirror's T-61 tube preamp is a tiny little wonder for ~$1K. It replaced a trusty CJ Premier 14 tube preamp as well as an Audia Flight Pre SS preamp in my system. It's innovative in using LED (instead of a resistor) to ground the tube circuitry.

Wow, so much fight after just one day! George and Charles, we've already known you are big fans of passive pre or source-direct, but at the end of the day, some of us will turn on an active preamp and some will go preamp-less. Who gets more fun out of music/audio is impossible to determine.

I recently found my iFi iUSB Power supply a great tool to charge my cell phone --- faster than my Samsung Note II's own wall-wart power supply. Yes it cost $199 plus shipping thus qualifies the most expensive cell phone charger I ever use. But I had more fun using it to charge my cell phone than to power my USB DAC ---- I was smiling ear to ear watching this little audio gem charging a cell phone (silly, I know). Anything wrong with that? Can you guys find me a passive cell phone charger that works better?