Ampeg SVT-4 Pro Issues
 

Hey guys, I'm new to the forums. I figured this would be the best place to ask my questions I've had about my head.

I am currently running an Ampeg SVT-4 Pro through an Ampeg 810E cabinet. I don't have it mono-bridged, I'm afraid of blowing out the cabinet from giving it too much power. I am currently running it through Power Amp A at 625W at 4ohms. I have the Speakon wiring correct for everything and the cab should be able to handle 800W so I'm guessing my setup should be fine.

My problem is that after about 2.5 hours of band practice, I get a loss in power and the amp gets extremely low. I can still hear the bass but its will fluctuate and get louder/lower when it wants to. Then eventually if I keep playing it will just stay low. If I turn it off for about 30min it's back to normal. I was thinking this may be an overheating issue however I've always heard other SVT4 owners complaining about it completely cutting out instead of a loss in power.

Thoughts?

First, that cabinet can handle everything that head can throw at it. Quit messing around and get that speaker cable wired for plugging into the bridged/mono output and make sure that the little button is depressed which links the 2 power amps. Now your head can relax, while at the same time blowing your eardrums out.

Why your amp is cutting out, I could not tell you why, but you are maxing out half of your amp while the other side is cold. Use both sides (A and B) and crank the volume. Let your ears be the limit switch. If any cabinet is being pushed too hard, it will let you know through farting and aweful distortion.

To add confidence, I use the bridged/mono connector into a SVT410HE which is half the power rating of your 810 and I crank it. Yes it draws power at the 8 ohm power rating, but get great sound and never have issues. If I was hurting that 410, it would tell me. Dont worry about the 810, unless it is an older single 1/4 inlet which may be only ~260 watts.

Thanks for the advice! I do have another cable that is wired for the mono-bridged option, I've just been too afraid to use it lol. I'll mono-bridge it tonight at practice to see if that makes a difference with the whole cutting out thing. If it keeps doing it I'll take it to a Ampeg repair center to see what the deal is.

Next time this happens, check out how hot the 4 PRO is running. Is the head in a rack case right now? Add a fan back there to get more air moving.

The head is in an SKB case with holes drilled into both side for ventilation. I'll reply to the thread later tonight after my band finishes practice. I'll also definitely get a fan for it too.

Also mike sure you dont have a guitar battery getting old on you (if it applies). Regardles, run that amp using Bridged Mono and give it a break.

Also, on the graphic EQ, I have the option to use the 33Hz frequency. However, in the 810 manual it says it's lower usable frequency is 40Hz. Should I just keep the 33Hz turned all the way down?

I get the impression that you read too many owners manuals...:hiding:

I would say, keep it flat, and let your ears me the judge.

Lol just trying to play it safe man. Thanks for you help!

When you turn this slider up, you are boosting between 33hz to 80hz on a slope (remember Math class?) I suggest not boosting this knob and during shows, it will be helpful to bring the slider down a little so your 810e is pushing less low end. This will lead you to hearing your bass tone better than before.

The sliders will also affect adjacent frequencies to 33hz. I don't know...I never found it useful to boost or cut that one. I usually don't even use the graphic on the 4 Pro when I use one.

As for your loss in power, might have a tube on the fritz. It would be the first thing I'd check anyway. Not a big deal to change tubes in the 4 Pro...I think it only has 3 tubes, right? Other than that, sounds like a tech would be needed. Someone else could tell you more about it than I can, but tubes are an easy fix so you might as well check them yourself.

I just ran it mono bridged and it worked like a charm all night!

Then it's likely not a tube...never mind my first post ;)