2. amps-preamps
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Peachtree Audio Nova125 & sensitive speakers

I wanted to inform any potential buyers of the Peachtree Audio Nova125 (Class D, 2x125W) its inherent incompatibility with high sensitive speakers. I learned this the hard way.

I own a pair of the excellent Klipsch Reference RF7 Mk.ii floorstanding speakers. They are horn loaded and have a very high sensivity (101db); you could practically run them on a clock radio. They used to be powered by a top-of-the-line Rotel pre+power combination. I sold this combo and bought the Nova125 instead because I wanted something simpler and/or more pleasing to the eye.

To my horror I noticed the Klipsch speakers produced a very loud hiss when connected to the beautiful Nova125. I had never heard this before with the Rotel combination. The hissing was clearly noticeable from 8 meter away (30 feet)! When the amp was switched on and nothing was playing, my living room was actually immersed in this horrible noise. The hissing was present and unaltered even when no source was connected and the volume knob was turned down to zero.

I contacted my dealer, who offered a new Nova125 and power conditioners. The hiss remained exactly the same.

I thus contacted Peachtree Audio directly. They simply stated that Class D amplifier tend to have a higher noise floor than typical Class A/B amplifier and that high sensitive speakers should be avoided in combination with an amp like the Nova125.

I am currently selling the Klipsch speakers and will buy the PSB Imagine T2 speakers, which are rated at 90db sensivity. I hope the hiss will not be present with these speakers.

All in all not a very pleasant experience.

I hope this will be helpful to anyone considering Peachtree Audio products (or any other Class D amp).
f_r_e

Showing 4 responses by mlsstl

mlsstl
1,378 posts
 
Two comments.

I used to have a Bel Canto S300 amp and there was no hiss whatsoever, even with my ear to the tweeter. It was dead silent. I don't buy the explanation that class D has an inherently higher noise floor.

Second, is there a source connected and on (but not playing) when you hear the hiss? If so, the origin of the hiss could be the source and a gain mismatch between it and the amp.
mlsstl
1,378 posts
 
After reading the other responses, I suspect the noise has nothing to do with the class D amps but is more likely coming from a noisy preamp section. Since you've had 2 different units that sound the same and someone else also has a noisy unit, it appears some hiss is just inherent to this model.

(I looked at the specs and they are a bit odd - Peachtree states the S/N ratio is 96 dB but then claims a dynamic range of 121 dB. Strange.)
mlsstl
1,378 posts
 
Bob Reynolds wrote: "It may be that the Peachtree product's filter doesn't attenuate enough for high sensitivity speakers."

By definition, ultrasonic noise in an amp does not create audible hiss - its beyond the range of hearing. At worse, if unfiltered, it is going to create an intermodulation problem in the audio band, but that only exists when music (an audible signal) is being played. In that case, you will not hear hiss, but rather some type of distortion in the music.
mlsstl
1,378 posts
 
Abrew19 wrote: I'm just trying to figure out who on this site (supposedly the high end) would actually buy one of those things.
I don't own one (I'm more of an old fashioned tube guy) but I have owned a Bel Canto class D amp (S300) in the past. It was a very nice sounding amp that I easily could have lived with if I hadn't decided to go back to tubes.

Not everyone has a ton of money to throw at high end gear and Peachtree gear has had excellent reviews in several audio publications and many nice user comments on the forums. We've got one fellow here with a specific problem that seems to be unique to his situation.

If I were shopping for an integrated amp in this price range, I wouldn't hesitate to audition one.
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