Ampeg B100R amp questions

Justice

Justice

May 24, 2002
2,157
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Houston TX.
#1
I went and checked out a old Ampeg B100R yesterday with the intention of purchasing it to have in my future studio. Overall it looked to be in good shape for the age (seller said it was from the 70s, i dunno anything about the history so I have to take his word for it) It was old enough that the lables for the controls were getting hard to read. still had both port tubes on the back.

I took my Squier Mike Dirnt bass to try it out. It had a pretty cool old school sound (strings are getting dead on the Dirnt) and I was liking what i was hearing. After a few minutes the seller asked me if I wanted to try his Fender jazz bass (Black w/black pick guard, maple fretboard and pearl blocks) so we plugged it in and was playing and then I started to hear something that sounded like static that would come after the attack of the note. At first I thought it was my bad technique (lol) but we kept hearing it. It would come and go.

It is really hard to describe.

We thought it might be the Jazz bass so I switched back to my bass and the sound was still there. I tried the other input and it was still there as well. Just some static/scratchyness on the end of notes. You probably would not hear it if you were playing with others, but if you were micing the amp for recording you would definitely hear it.

He did say the amp had been in storage for a while (did not say how long) and I'm wondering if it just needs to be serviced/cleaned.

Any thoughts?
 
#5
cfsporn said:
If it's been in storage for a long time, the effects jacks may be corroded. Try jumping them and see if the scratchyness is still there.
Click to expand...

The B100R does not have an effects loop.

chaosMK said:
I thought the B100R was a more recent invention. Vintage look but probably made in like ~2010.
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I have not been able to find any reliable history on them so I have no idea, and since it was making the static scratchy noise, I never looked at the back panel or badges.

It did not make any scratchy sounds when turning any of the controls or messing with the cord. Although inserting the cord in the -15 input was not as easy as the -0 input.
 
#6
It could be a bad connection due to jack corrosion. Spray the male jack from your instrument cord with contact cleaner and insert - do this a couple times (better than spraying into the interior of the amp).

Check the hardware for rust - it is an indication of storage conditions. If rust is present, the storage environment was humid - not good for electronics.

A cap or other electronic component may be going bad. A tech would have to check for this. There is really no way to tell before the sale. Make an offer based on this uncertainty. The static may go away after a while, or it could get worse. If you really like the amp, and it is in otherwise good shape, and you could afford a repair bill, this could be a good opportunity.
 
#9
Doing a little research, the furthest back mention I can find of the B-100R is the early/mid 90s. I'm not sure if the seller is intentionally misrepresenting the combo to sell it at a vintage price or just ignorant to its actual history. Just factor that into your negotiation if you can figure out the static issue. When working properly the B-100R is an awesome combo. I have the B-50R and love it. One of the best sounding SS amps stuffed into a combo format.
 
#10
anderbass said:
The headphone jack has switching contacts that mute the speaker, so make sure you clean that one out too...
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Headphone jack most likely. Plug some headphones in - if noise is gone = from that jack onwards.

Someone clipped on a wire that negated that headphone function and that solved it. Their solution was soldering a permanent wire as they had never used that socket.

IIRC there's a speaker plug into rear of amp unit. Unplug it and try a different speaker cable & cab. If noise gone = problem from that plug onwards.

@Justice - let me know if these two sort the issue.
 
#11
What you're describing sounds like it could be 'crossover distortion' from mis-biased transistors. "Static" is generally a random, crackling sound. Hum and/or buzz are at power line frequency (60 Hz) or a harmonic of power line frequency (120 Hz, ect). Crossover distortion is a sort of fuzz on top of the clean signal that's most noticeable just as the note fades out. If the amp has an internal bias trimmer, it's relatively easy for a tech to dial it in. I would strongly advise against attempting to adjust yourself without proper documentation.
 
#12
Justice said:
The B100R does not have an effects loop.



I have not been able to find any reliable history on them so I have no idea, and since it was making the static scratchy noise, I never looked at the back panel or badges.

It did not make any scratchy sounds when turning any of the controls or messing with the cord. Although inserting the cord in the -15 input was not as easy as the -0 input.
Click to expand...

Long time B100 user here. First off, it's the best solid state combo ever! It's a 90's invention as far as I know, a SS cousin to the B15 if you will. Maybe the guy just thinks it's vintage because of the look.

The minus 15 input was probably never used, so the jack is still as snug as the day it went out the factory.

I had a very similiar problem on mine. When a note was decaying, I would here a sort of crackle or static that accompanied it. It was not on every note, but stuck out like a sore thumb when you hit the notes that made it happen. You couldn't hear this at the front of the note, but I suspect that the volume and punch at the front end of the note was just louder than the problem.

I took mine to tech. Turned out that the speaker terminal connector(s) were loose. They weren't bouncing around in there but must have been a frequency that rattled them enough to cause some electrical misgivings. Snugged/cleaned all of that up and it's been worry free for years. The guy didn't even charge me for it.

Also - I would be careful before I sprayed contact cleaner in there....in fact I wouldn't.

If you have a decent tech you know will check it out, I would make the guy a reasonably discounted offer. He was standing right there and heard the problem, so he's not in position to argue that the amp does have some issues.
 
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