ampeg svp-pro problem

[deepestend]

I've got a problem with my svp-pro pre that maybe someone can help me to diagnose. The problem just started recently. It seems that no matter what I do, the signal that I put into the pre overloads and distorts the sound. It's definitely a problem with the pre. During practice tonight, I plugged my bass into my dbx compressor, turned it all the way up, and plugged the output into the cabs. Of course, it sounded a little flat, but it was good enough to get through a rehearsal. Any thought on what the problem might be? It seems that no matter how low I turn my bass it still overloads the pre.

 

[Eric Moesle]

Replace the tube and call me in the morning . . . .

 

[deepestend]

2 questions:

1) which one, or all of them?

2) can I do it myself or do I need to have someone do it for me?

 

[deepestend]

bump

 

[Jerrold Tiers]

There are a lot of things that can do that.

Tube is naturally one of them, but tubes are actually pretty reliable if decently made (a question these days). You can always swap out tubes and see, if you want. I'd just do one, and then the next if the first one isn't it. Needs fewer replacements that way.

Possibly a loose connection. Most likely a simple fix....is it under warranty? If so the price of repair is right.........

 

[deepestend]

Thanks for getting back to me.

I bought it used here on talkbass last year, so it's not under warranty.

Where do you suggest I start? Is it safe to just open the SVP up and check that the connections and tubes aren't loose?

Should I get one tube and just try and switch it out and go down the line? Is this as simple as pulling the old one out and plugging the new one in? (I do know that there are two diff. kinds of tubes in the pre).

Thanks for any help or any quick troubleshooting pointers. One thing I need to try is to just plug into the effects return loop to make sure that it's not a problem with the input jack.

 

[Eric Moesle]

Should I get one tube and just try and switch it out and go down the line? Is this as simple as pulling the old one out and plugging the new one in?

That's where I'd start the troubleshooting process. Just get one new tube, and start going down the line. JUst pull them straight out gently, and gently push the new one in, being careful not to bend the pins.

 

[Jerrold Tiers]

Changing tubes is indeed just that easy, so long as you unplug the unit, turn it off, and don't touch anything inside except the tube..... But there are dangerous voltages inside, not for the novice to meddle with.

While it *could* be a tube, I suspect something else, bad connection etc.

We mark the units with "do not open......" for a reason. If you are not familiar with electronic servicing it may be better not to attempt fixing ANY electronic device.

The SVP has high voltages (300V) in it, voltages which CAN be fatal if contacted. Even if you only get a painful shock, I can assure you from personal experience it is not fun.

"Can I fix it myself?" is sort of like the famous question on the cost of a yacht..... if you have to ask, you probably shouldn't try it.

 

[deepestend]

Gotcha. I will take your advice. One obvious and maybe dumb question. If when I turn the SVP on one tube doesn't start glowing, would that mean that that tube is shot? (I just thought of this and haven't tried it out yet).