2. analog
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phono preamp crackling

i recently added analog to my system and i'm having a problem. my phono preamp will often emit crackling noises. this occurs even when i take the stylus off the record--the crackling will continue.

i've tried locating the preamp in different locations--above the turntable (very bad), below the turntable (better but not good) and as far from my integrated amp as i can, which isn't too far, about 1.5 feet above the amp. the impedence and gain settings on the preamp are at the recommended level for my MM cartridge.

if location of the phono preamp is the problem then i'm in trouble, as i don't have many options for where to put it.

the phono preamp is connected to my integrated amp using balanced cables. the system is: marantz 15s1 tt, ps audio gcph phono preamp and cambridge audio 840v2 integrated.

any suggestions on what to do or what the problem might be?

thanks!
tanglewood
photon46
1,088 posts
 
Assuming you're using the stock Clearaudio cartridge the Marantz ships with, you're working with a 3.6 mv cartridge signal. That's pretty middle of the pack, nothing unusual there. Not sure exactly what the GCPH's lowest gain setting is, but I'd make sure you're using it. (That gain block is adjusted with the left blue knob on the back of the chassis.) I wouldn't think a 3.6 mv signal should overload any competently designed MM phono stage. Also make sure the output gain of the GCPH isn't set too high also. Don't want to overload the input on your Cambridge either.
axelwahl
788 posts
 
Photon46
GCPH has 40dB RCA and 46dB when using XLR for it's low (MM) gain setting --- and of course 47k loading not to forget.
Then you can use the 'volume knob' for further adjustment. NO WAY will you overload ANY functioning Line-Pre-Amp with a 3.6mV cart that way - rather the opposite would be the case since ~ 4.7mV be pretty much centre spec. for the GCPH.
Greetings,
zenblaster
504 posts
 
I would start by disconnecting all inter-connects to the int. amp except the balanced phono pre, then check. If problem is still persistent I would then start checking tubes.
Finding unwanted sounds is a process of elimination.

Your suggestion that it was fine until warmed up leads me to think it is probably a problem in the tubes.
jimjoyce25
215 posts
 
Is there any effect when you touch the controls on the preamp? Or is the crackling independent of that?
tanglewood OP
43 posts
 
as noted above, i do not have tubes in my system, ergo tubes are not the problem.

i don't notice problems when i touch the controls of the preamp--i think the crackling is independent of that, so the preamp is likely not the problem. on the other hand, the preamp may be very sensitive to static. i can still get crackling when i've turned the TT motor off and taken the arm off the lp.

i ordered an ionoclast today and it should be here by the end of the week. after i use it, i'll post on how well it worked. in the meantime, if anyone has other ideas please let me know.

thanks.
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