Ampeg B100R Problem

sevenyearsdown · #1 09-02-2010, 08:16 AM

I picked up a used MIA Ampeg B100R a few months ago. I just noticed playing the other night that it has some sort of issue.

When the notes are sustaining/decaying you can hear a faint sizzle/buzz thing happening. It's not a vibration, and pretty much happens with every note played - but varies in amplitude with the amp/bass settings.

I have tried adjusting the eq, swapping guitar cables, switching inputs, swapping basses, even tried a different electrical outlet (on a different circuit). Same result each time.

I also took the grill off just to inspect the speaker. There were no visible problems on the speaker, and the phantom sizzling seems to be of the electric type of noise and not vibration in cabinet somewhere. Even when playing at very low volume it occurs.

A friend who a bit of an electrical buff suggested I might have a poor solder joint. However I am not about to start any board level troubleshooting. I'm looking for good solid state tech in my area.

Have any of you B100R guys have similar issues?

JimmyM · #2 09-02-2010, 08:46 AM

did you try pushing the speaker around the dustcap and feeling for rubbing? if it doesn't rub, then yeah, you might have a cold solder or something. but if it rubs, the voice coil's shot and you need a recone or replacement.

stiles72 · #3 09-02-2010, 01:45 PM

Check the cardboard tubes inside the ports on the back. Sometimes they come loose and create a buzzing/rattle. If they did come off, just unscrew the port flange, take the tube out, and I would re-attach with some duct tape to keep them in place. I've had to do that with my B100R and my 2x15 Simmons Ampegs.

Dino@Ampeg · #4 09-02-2010, 02:03 PM

Does it sound like sort of an underlying distortion that comes in as the note decays?

If so, it might be in need of a simple bias. It's an easy thing to do but you really should have a tech do it if you don't know or have the tools to do it.

You can go to this link and type in your zip code and that will give you a list of warranty and non warranty repair shops...
http://www.loudtechinc.com/corecgi/f...ceCenters.aspx

Hope this helps!

JimmyM · #5 09-02-2010, 04:29 PM

even better call than mine, dino.

and yeah, biasing has to be done by a tech or else you'll have a b100r extension cab.

good to see you on here again, dino...heritage stuff looks great...got any stores in central fla i can try one out? i'm holding out for the b-15n reissue

but i still want to plug into one.

sevenyearsdown · #6 09-03-2010, 05:19 AM

Quote:

Originally Posted by Dino@Ampeg

Does it sound like sort of an underlying distortion that comes in as the note decays?

If so, it might be in need of a simple bias. It's an easy thing to do but you really should have a tech do it if you don't know or have the tools to do it.

You can go to this link and type in your zip code and that will give you a list of warranty and non warranty repair shops...
http://www.loudtechinc.com/corecgi/f...ceCenters.aspx

Hope this helps!

That is exactly what it sounds like. Thanks for the suggestion.

Just curious though about these service centers. None of them near me say anything about music gear. In fact - one is a Radio Shack. The last thing I want to do is let some Radio Shack employee start fussing with my gear.

I will call a couple of them today to see what the deal is though.

Groover · #7 09-03-2010, 06:01 AM

Mine sort of does the same thing. It's basically new (was on old stock USA) I snatched up last year from a small town music store and have hardly used it.

Does the BIASing do anything else other than fix the rolloff fuzz factor?

I know it helps the power section in the SVT, just not sure what it does in solid state amp.

Jerrold Tiers · #8 09-03-2010, 06:40 AM

It does exactly the same thing. That's all it's for. Some manufacturers have made the bias fixed for SS gear, and some have made it fixed for tube gear. Most give some sort of adjustment.

My name is Mudd · #9 09-10-2010, 07:33 PM

My MIA Ba210sp also does this at lower volume settings...should I look into biasing also?

sevenyearsdown · #10 10-18-2010, 06:58 AM

Here's an update for you guys.

Turns out the bias was fine. The local tech who worked on found some bad/loose speaker connections. I couldn't tell you if this was wear and tear from the previous owner, or if it was like that from the factory.

The tech told me that he took the speaker out for inspection, and one of the leads fell right off as he was removing the speaker. He corrected the problems with the speaker leads and the problem was solved.

So it was an easy fix on mine. Before you pay someone to look at it, check the speaker connections if you are comfortable doing such a thing.

I put mine through the paces again yesterday - what a great little amp.

Jerrold Tiers · #11 10-18-2010, 09:37 PM

They can be very hard to distinguish.....

Air leaks and loose connections and bias can sound similar, all bad!

heads and separate speakers are much easier.... try with a different speaker and many questions are answered. Not so easy with a combo.

And everything sounds the same over the internet............