Spotless Ampeg V7 (ampeg reverb question)

[xJasonSmithx]

So I received a spotless Ampeg V7 head recently in a trade. Pretty interesting so far. I haven't had too much time to play with it.

My only qualms so far are;

1. It is wider than normal cabs because it is a guitar head and I think is looks funny on top of bass cabs.

and more importantly

2. The reverb is really weak. Cranked all the way it is little more than a country sounding slap back echo sound. Is this what the Ampeg reverb is supposed to sound or is this something that needs to be repaired? Any clue what it could be? Obviously reverb isn't the most important thing but I like using it in conjunction with my volume pedal for swells and more atmospheric sounds. It would be a lot of fun if it could achieve a big cavernous reverb tone.

Thanks for your help,

-Jason

[NecroticImbecil]

Might not hurt to have it looked at. I do not recall the reverb in mine being weak; actually traded it to a guitarist who liked the reverb, uses it with pedals as its distortion is pretty terrible.

[metalmariachi]

The reverb should be thick and rich better than a Fender’s.
Check the reverb driver and recovery tubes they are most likely the problem.
They will be the 6CG7 and the 12AX7 numbered V203.

MM

[xJasonSmithx]

What will I be looking for when I check them exactly? I am new to tube amps.

[JimmyM]

you are looking for tubes that run the reverb that don't work. you might want to get a spare tube of each kind for the reverb and swap them out and see if it improves. if not, then you have a couple spare tubes for when you need them and then you take it to the local amp repair shop. if it does, then you're fixed.

[coreyfyfe]

Does it still have the reverb lock on the back like the V4 had? I had one on my V4 and the first few times couldn't figure out why the reverb barely worked when I turned it up, but later figured out the lock.

Might not be your problem but I figured it would be good to cover the basics

[xJasonSmithx]

Corey, I am not sure. How would I find the reverb lock? The spring tank is covered with tolex so it is hard to see. That could be the problem because the springs do not really rattle around when moving it.

[coreyfyfe]

On the V4 it was the piece of metal sticking out of the top of the chasis above the "footswitch" jack (far right in this picture). Like I said, not sure if they had that on the V7, but it was my only guess aside from a bad driver tube on the reverb as mentioned above.

[xJasonSmithx]

So I had a someone look at this and they said the tubes are fine it just needs a new reverb tank. Which tank would work as a replacement? Fliptops said call Ampeg but they Are probably not open until Monday morning I assume.

-Jason

[Jerrold Tiers]

Hasn't been a decent reverb tank made in almost 20 years...... IMO of course...... maybe it's only 15 yrs.

There isn't a lot to go wrong inside of one, unless pieces fall off, so before agreeing that it is bad, it might be as well to have some other smart repair person look at it decide if it really is bad, and explain just WHAT is bad.

[anderbass]

Might be worth a try to fiddle with the reverb tank rca plugs, sometimes they just loose connection and you can get the verb happening again just by twisting or pulling them off and re-plugging in.

[xJasonSmithx]

The guy who looked at it tested the tubes and said they were not bad. He seemed positive the tank was the problem.

[xJasonSmithx]

I will talk to him and see if he remembers what exactly was wrong with the tank.

in the mean time, anyone know which tank will work?

[xJasonSmithx]

Talking to him now, he said that the transformer in the tank was bad.

[Jerrold Tiers]

Originally Posted by xJasonSmithx

Talking to him now, he said that the transformer in the tank was bad.

He probably meant the coil..... Can happen. Although most tube amplifiers use a small output type transformer to drive the tank coil, which is often an 8 ohm coil. the 'tanks" were available in 8 ohms, 150 ohms, and IIRC at least one higher impedance. I have the old catalog somewhere. The transformer is really part of the amp, though.

The way most all of the reverbs work is that there are springs stretched between supports. Uaually there are at least two slightly different springs in parallel, and each spring is made up of two slightly different springs in series, with a glued joint halfway down the length.

There are little tubular magnets on the small wires that support the springs. The magnetic coils which are driven by the electronics twist the tubular magnets, and so give a twist to the spring.

That "wave" of twisting travels down the spring, at a slower rate than actual sound travels, making the small springs a sort of "analog of" a larger room.

The "wave" of twisting partly "reflects" off of the joint between springs, and partly reflects from the far end of each spring. Similar to sound reflecting off walls. At each reflection a little is lost, so the sound dies out, just like a real room.

The different springs are like the distance floor to ceiling, left to right, end to end, etc. So pretty soon you get a complex sound that sounds "kinda like" real room reverberation.

As for what goes wrong......

1) a coil can be "bad" with a shorted turn, etc. With sufficient motivation, like a no-longer-available reverb tank, that can be re-wound and thus fixed.

2) the little tubular magnets can get loose, which drastically cuts the sound.... then they don't put any energy into the spring. With care they can be glued back to fix an "NLA" part. You MUST be sure to get the magnet glued back with the "north" and "south" poles parallel to the "gap" in the drive coil and not lined up across it. The coil must be able to apply maximum twist, and that can only happen if the drive magnetic field is at right angles to the little magnets.

Ditto for the pickup..... for maximum signal OUT of the coil.

3) the end supports can come loose. That's harder to fix, but possible.

4) springs can break, or become stretched out, etc, which is probably gojng to make the tank toast.

[xJasonSmithx]

Could anyone provide me with a link to where I can purchase a new tank that will work? I can get pics of the old tank up sometime soon.

-Jason

p.s. The guys at flip tops said they did not carry it.