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Buzzing sound from Peachtree Nova 150 - anybody else had similar experience?

I bought Peachtree Nova 150 around 10 months ago. While I was very satisfied with the amp to begin with, I slowly started getting more bothered by the high frequency buzzing it makes when it is powered on. The sound comes from the device itself, not from the speakers, very high frequency, similar to the sound from old CRT screens. It is very noticeable when standing close to the device, but if it’s otherwise quiet I am also hearing it as long as I am in the same room. And though I probably will be able to ignore it while playing music, it does bother me as long as there’s a pause in the music or while watching movies. I don’t think I am being overly sensitive, I have other electric devices that make far more noise, like my projector or hard drive RAID, but it is just the high pitched whine from the Peachtree Nova that bothers me. With simple measuring software on my phone, the sound is measurable from about 1 meter from the device, and shows up as a sound with a peak of 8 kHz and a smaller peak at 16 kHz.

After I sent complaints to the dealer I bought it from, the the amp was sent back for repair. Twice. Both times it came back with absolutely no changes to this issue, as far as I can hear. The guy who did the repairs measured the sound after the last repair to be "significantly reduced". But I can’t hear any difference. He indicates that the current in my house can be the culprit, but I have also tried it in my office building, both in grounded and ungrounded outlets, without any changes to the buzzing. What I haven’t tried yet is any kind of expensive AC filter to deal with noise. Could I expect that such a filter (fx IsoTek Corvus) would make any difference here? I am hesitant to try it, since I wouldn’t expect that a relatively expensive amp (for me) would need such a thing just to function properly.

That the repair shop claims the sound is "reduced" indicates to me that some kind of buzzing from the device itself is to be expected, just that it should be at a significantly lower level than what I am experiencing. Is this on par with with what other owners of Peachtree Nova have experienced - could I expect it to be dead quiet?

It seems to be the same issue discussed in this thread.


oysteinvidnes
audioman58's avatar
audioman58
3,952 posts
 
Many times it is the transformer ,at the 50-60 hz region mechanicalhum 
the better transformers donot do this much since they are double potted in
Opoxy for vibration .Torroidal transformers. Are by far the worst offenders.
Piltron  , Triad  make very good models myself have paid extra to get  the Black 
double potted Piltron  transformer if this amplifier you are Very happy with .the 
transformer itself is under $100. Speak with peach tree. I doubt they  used a top 
transformer .personally  I see this happen all to often for an extra $30-40 dollars 
when being built would avoid a lot of this problem ,another issue is their grounding scheme .if all used 3 point star grounding this extra step would eliminate a lot of headaches. It is very frustrating I  went through 3 amps  one time 3 different brands  just to get a good one . Pass Labs never an issue, 
spread Spectrum ,Son of Ampzilla fantastic dead quiet , just an example of 2 of my current amps .
oysteinvidnes OP
5 posts
 
Update: The dealer agreed to have the Nova exchanged, and I had it exchanged for a Nova 300. But: The 300 has more or less the same issue. The buzz is a bit lower in volume, but somehow more aggressive, and enough to bother me. So either I am overly sensitive, or the Novas in general react negatively to the mains line in my area (and there wasn’t anything special up with my old Nova either, after all). I have ordered a PS Audio Dectet filter, and if that does not take care of the issue, I have the option of returning both the filter and the amp.
almarg's avatar
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almarg
9,670 posts
 
By any chance are the speaker-level outputs of the amp connected to a powered sub, or to a speaker that incorporates a powered woofer, or to anything else that is powered?  If so, given that the speaker-level outputs of the Nova 150 and 300 are described as being differential, and the negative output terminal as well as the positive output terminal therefore has a full amplitude signal on it (which might be grounded via some unknown impedance in a powered speaker or sub), that could conceivably be the root cause of the problem.

Regards,
-- Al
 
oysteinvidnes OP
5 posts
 
The sound is the same without anything connected (except the mains cable, of course), and whether or not the outlet is grounded.
oysteinvidnes OP
5 posts
 
I received a current filter that I had ordered, but using it makes no difference whatsoever. 

I am now in contact with Peachtree, and they are willing to replace the power supply in my Nova 300. I am glad they are taking this seriously, but at this point I am not confident that the issue will be resolved, since I already went through the very same process with one unit of the Nova 150. Maybe I’ll give it a shot, but I am guessing that the Novas in general just don’t play nice with the mains line in my area. Or I am being way more sensitive about this than any other Nova owners. But I really find the buzzing unbearable.

Here’s a recording of the sound (sound begins about six seconds in, turning on the unit first).


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