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Problem - HF "Chirping" Using Turntable

To make a long story short, my PS Audio 5.5 preamp, Hafler DH-500 power amp and Acoustat 1+1 speakers have been thoroughly checked out, and they appear to not be the source of the problem below.

I installed a new Audio-Technica MM cartridge and since then (but the above components are "new" too) when my phono section is engaged, at high volumes there is breakthrough of a very disconcerting high frequency chirping or oscillation. When I move my TT to my (lower quality) home theater setup, there is no such noise.

So, I figure either my Tt (a KAB Acoustics-modified to play 78 rpm - Technics SLBD-era belt-drive TT) or the AT cartidge is the source of this noise or it happens to exist at the location of my system and the cartidge is amplfying it.

Any thoughts? My line-level channels are fine - silent.
toxrtp
toxrtp OP
6 posts
 
Problem solved. I "borrowed" a Grado Green P-mount cartridge from my local audio salon and it does not make the noise. I will contact the vendor of the Audio-Technica cartridge but, as it's months old (my system was down being repaired and upgraded for the past 8 months) I don't expect to receive much consideration From "the Needle Doctor", even though both the cartridge and extra 78 RPM stylus are essentially unused. It would be really above and beyond in terms of customer service.

Follow-up question: Given that I have a Technics SLBD-5 TT and only use it to play records that will probably never be available on CD, which means a few hours of play per year, is there any reason for me to upgrade my Grado Green P-mount to a Grado Red P-Mount?
crem1
672 posts
 
No, not in my opinion ; go green and enjoy the music.
toxrtp OP
6 posts
 
Thanks to my local audio salon, I have discovered that the squeal is feedback between my Acoustat 1+1 electrostatic panel and the turntable, cartridge or stylus' cantilever system. The closer the TT is to the panel, the lower the volume that causes the squeal. Unfortunately, I cannot separate the TT from the panel. (They're about 6-12 inches apart). Does anyone know if I get rid of the Technics SLBD-22 and go for an entry-level Pro-Ject, Rega, Music Hall or other TT, will the increase the likelihood of the problem going away? Or, will a change in TT that will allow me to use a universal-mount cartridge instead of a P-mount (see earlier discussions above) offer me a greater chance of an affordable yet feedback-resistent cartridge? (By the way, the noise floor on th eGrado is much higher than the Audio-Technica, though it's the Audio-Technica that feeds back. Plus, I think the high-end extension is not as much on the Grado - which might be the reason it doesn't feedback.)
crem1
672 posts
 
The grado is a moving iron rather than a moving magnet(audio technica) designed cartridge. Each design works differently to create a signal. Moving Iron Carts have 47K OP so they work with MM PreAmps; however, they can cause hum in TT's that don't shield the motors, ie Rega / AR .

You might consider a dedicated electrical line isolating the TT from all other elements of your system.
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