2. analog
  3. 1248625946

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
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.
almarg's avatar
almarg
9,670 posts
 
Although a defective phono stage is certainly a possibility (perhaps a marginal capacitor), it sounds to me like a good possibility would be that you are picking up rfi/emi (radio frequency interference/electromagnetic interference) from a fluorescent light fixture, a dimmer switch, or some other device which (like those) can generate significant rfi/emi.

Aside from turning off any such devices which may be nearby, what you could do that might be helpful is to take a portable transistor am radio, tune it to an unused frequency near the bottom of the band (near 540kHz), and during times that you hear crackling from the audio system see if the radio picks up corresponding crackling static-like noises. If so, you may be able to zero in on the source of the rfi/emi by walking around with the radio and noting where the volume of the crackling becomes loudest.

HTH,
-- Al
vonhakemarine
55 posts
 
1. Make sure your rca females are clean of all oxides.
2. Ensure the IC's are gripping well. I was "sure" I had good IC's / connections and still had perplexing problems like yours until I got the outer casings of my rca's compressed a little (they had expanded just enough from being swapped around multiple times). Be carefull not to crack this tender area of the rca when compressing. Take note of the location of the plug casing slits and compress to close in these gaps a bit.

The above costs nothing: UNLESS you break a plug!
Good luck
tfkaudio
591 posts
 
I would first try grounding your table to the phono amp. Also, make sure you're not using the moving coil setting with a moving magnet cartridge.

Cheers.
tanglewood OP
43 posts
 
i promised i'd post a response once i figured out what was going on. i'm fairly sure i know where the cause of the crackling lies.

first, some have speculated that i have noise in or around my system. there are no fluorescent lights nearby (at least that are on), and i have two dedicated lines from my breaker box to a quad receptacle to power my hi fi equipment. so i don't think that is the problem. also, i tried the suggestion from almarg, and set my tuner to an am station but did not hear any crackling through the tuner.

i think the problem is in the phono stage itself. the only way i can get the crackling to stop is by tapping on the back of the gcph. the crackling stops completely. note that i have made sure all the connections in and out of the gcph are secure. i'm using balanced connections out, the grounds from my TT are very tightly secured, as are the rca's from the TT. again, a couple taps towards the back of the phono stage and all crackling is gone, at least for awhile. i figure there is something loose in the phono stage.

if you have any other thoughts let me know and thanks again for all the suggestions.
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