Studio Pre help

[PenCapChew]

I have a studio pre connected to a crest 4801 power amp. I am getting an annoying 60 cycle hum.

I have tried using a cheater plug to lift the ground on one amp (dangerous, I know, but only for test purposes) - hum is still there. The mains are connected to a common ground and I am using a balanced, shielded 1/4" TRS to XLRM to connect the amps.

My next option was to buy a new 1/4" TRS to XLRM too determine if the cable is what is causing the hum.

I have read on the internet that cutting the screen on one end of a balanced cable may get rid of the problem. Maybe I should try this next? I'm also wondering whether the Main Outputs on the studio pre are balanced or unbalanced... it doesn't say in the manual, am I missing something?

The rig is totally playable, I just want to get rid of this stupid hum that is present in the background. It's not in a rack at the moment. It's sitting on the ground with the ground lift switch in the normal position

Any feedback is greatly appreciated. Just want to enjoy me new rig without the hum!

 

[Markedman]

Have you tried your studio pre with a different amp? You could isolate the problem if you can determine if it is the pre or power amp. The crest 4801 is a super powerful SS amp, maybe a nice tube amp, just about any tube amp would work wonders for you and your pre amp. Try coming out the effects send, I like line level myself, into an old Marshall or Fender. Make sure you set enough time aside because you will not be able to stop playing when you hear the Studio pre through a tube amp.

 

[r_cod_81]

I run my studio pre into a wee 5W amp I made from a kit and it's awesome for playing in the house (I'd totally record with it too). For 'Loud' I go into a Marshall 8008 and that sounds great too (I run it on the 'Linear' setting which is solid state).

Re: your buzzing - are both your pre and power amps rach-mounbted and running off the same wall socket? Have you tried using the 'Ground Lift' switch on the back of the studio pre? That worked for me whan I had buzzing poblems caused by ground loops from two different mains power sockets.

Your problem may be the TRS connectors, I believe the pre is desined for regular mono (TS) jack plugs so maybe try a TS from the pre going to the TRS XLR for the power amp input (connect R and S together on the Pre end).

 

[MichaelC4]

http://vintage.guitargeek.com/rigview/522/
I knew someone else was using a Mesa preamp to feed a Crest 4801.

 

[Markedman]

That explains Kirk's crappy sound, he ran his cords backwards through his effects.

 

[Mickel]

That explains Kirk's crappy sound, he ran his cords backwards through his effects.

I'd just drop the earth from the pre

 

[PenCapChew]

Have you tried your studio pre with a different amp? You could isolate the problem if you can determine if it is the pre or power amp.

I tried it with a different power amp. It was also SS though. The hum persisted. I also plug it directly into my mixing board and I still get the hum. So it's definitely the preamp causing the hum.

I'm open to trying it with a tube amp sometime in the future. Maybe a fender deluxe or Orange Rockerverb? I'm still getting the tone I love with this setup, whether others like it or not

Re: your buzzing - are both your pre and power amps rach-mounbted and running off the same wall socket? Have you tried using the 'Ground Lift' switch on the back of the studio pre? That worked for me whan I had buzzing poblems caused by ground loops from two different mains power sockets.

Your problem may be the TRS connectors, I believe the pre is desined for regular mono (TS) jack plugs so maybe try a TS from the pre going to the TRS XLR for the power amp input (connect R and S together on the Pre end).

They are running off of the same wall socket. Even bought a new expensive powerbar and tried it on that. Same deal. I don;t have it rackmounted yet though. Don;t want to commit until I figure out this issue. The amps are just sitting on a carrying case. I have tried the ground lift switch. Doesn't make a difference.

As mentioned above I still get the hum when going directly into mixer. Does that rule out the TRS connector? If not, is there anywhere I can buy a chord like the one you mentioned? I'm not very handy at making my own.

Thanks all!

 

[firmani99]

I would try using a standard tip ring instrument cable into an xlr adaptor if that is the only input on the amp. If that doesn't fix it try cutting the braid on the cable. I bet that will fix it.