Studo Pre problems - help?

[Thrashman]

So i bought a used studio pre and it looks like its new and sounds good at low volumes.

But when turned up, it's a different story.

the preamp makes a hiss/hum noise, and some barely audible static noises when in play, but guitar volume turned off.

the standby switch does also not choke the signal, only makes it lower and thinner.

the feedback is UNCONTROLLABLE, when i have the master at 7, volume at 7, lead gain at 7, and output at 3.
even more so when i use the main outputs.

And i use an MXR Smartgate in the loop and in front.

the bass seems flubby whatever i do aswell and yeah, the tone knobs are not responsive at all, they barely make a difference.

also seems to make a static noise even when i play through it.

what can i do? should i return it and just keep using my old head, or give it to someone that can fix it(service?) and swallow the cost?

 

[kekam35]

Should have bought the DC-5, What happened to that?

 

[Thrashman]

buyer was an ass and wouldnt ship it, even with the flightcase.

the tone is great but i dont know what's with it, if it's something other than the preamp or what.


would buying a better poweramp solve it? I'm running it in a peavey VK in the effects return jack to bypass the preamp of it.

 

[Whoopysnorp]

I have two Studio Pres (well, one is my roommate's but I'm the one who uses it most) and the standby switches on both of them behave more or less as you describe, although they do very nearly eliminate the output signal. I have to be turned up pretty loud to notice the thin signal coming through when the pre is on standby.

As far as the noise issues: how loud are we talking here? Is this on the lead mode or rhythm mode? The 'barely audible static noises' you describe sound to me like a noisy tube somewhere in the signal path--I have had the same thing happen with some bad EH 12AX7s in my Studio Pre. Volume and lead gain both at 7 is A TON of gain; I'm not surprised you're getting a lot of feedback. If any of the tubes in the preamp have gone microphonic, that would certainly contribute to that problem as well. Obviously, the louder you get, the more you'll have a feedback problem.

The tone knobs on most amps with the Mark series topology, Studio Pre included, do not behave in the way that the tone knobs on most other amps do. They are for shaping the character of the distortion--for example, the more treble you add, the sharper the higher-end content of the distortion. Turning the bass knob past 1 or so will make the bass flubby real fast. Use the graphic EQ to control the overall tone and add bass back into the signal.

It sounds like your issues are due to unfamiliarity with these types of amps, coupled with some actual signal problems somewhere in there. There's about a 90 percent chance that it comes down to the tubes, which is good for you because that is solved relatively easily and cheaply. If, after re-tubing, you still have noise and feedback issues, it is possible there could be something up with the circuit.