Ampeg SVT 210HE Crossover/Tweeter Problem

[felixbuchner]

Hi,
I've had a buzz on the tweeter of my Ampeg Cab for a while, it's only there when the tweeter is on, so I figured it's blown. Now that I took it apart, it turns out the tweeter is fine, I tested it on another amp and no buzz.
But when I connected a different speaker to the tweeter output of the cab, the same buzz was there.
So I guess something on the crossover must be broken, but I can't figure out what, or where to find a replacement. The connections on the board all look fine to me, so does the lightbulb.

Anybody had the problem before, or any ideas?

There was a similar thread years ago, but no solution as far as I can see.
=> Ampeg SVT Cab Crossover

Thanks for your help!

Felix

 

[agedhorse]

Nothing on that crossover is causing your symptoms.

Noise within the amp will be reproduced by the tweeter. Disconnecting the tweeter removes the ability to reproduce the high frequency noise.

 

[felixbuchner]

Hm I thought I ruled everything else out:
- With a different head the cab/tweeter produces the same noise
- Both heads produce no noise on a different cab (that also has a tweeter)
- A different speaker wired to the crossover's tweeter output produces the same noise, regardless of the head i'm using

Maybe "buzz" isn't the right word, it sounds distorted, as if the tweeter is getting a bad/overpowered signal.

I've been using it with the tweeter turned off lately and it works just fine, but would be nice to have the tweeter working again still. I just don't know what causes it.
Both amps are definitely fine on other cabs

EDIT:
I found this old thread now, describes exactly my problem.
Only that I don't have any loose or broken wires (visible) on the board.
Ampeg crossover help

 

[agedhorse]

You are making assumptions that aren't accurate.

The tweeter may be damaged, but there's more troubleshooting that's necessary to result in something better than a guess.

There's a possibility that there's damage to the crossover, but that's not very common (at least until somebody attempts to "fix something that's not broken". Can you post a picture of the bottom side of the PCB?

 

[felixbuchner]

I took the light bulb out for visibility

 

[agedhorse]

There are two additional possibilities, the first is that the bulb socket is intermittent (reinstalling the bulb should clear that up).

The second possibility unique to this particular PCB type and fab design rules used, is that there are hairline fractures on the 4 pin Molex .156 header (that the 4 wires plug onto).

Properly resoldering these connections (with the correct solder/flux) will solve this (IF it’s the cause).

Note that my comments are specific to this particular crossover, it is not applicable to crossovers in general.