Hey all! Long time lurker here. Every once in a while though, I have a question that only the Teeming Millions can answer. So, here it goes:
Last night at my weekly band practice, my bass amp didn’t sound so hot. Whenever I hit a note, it would make a popping sound. The notes were audible, but as I let them ring out it would start making the popping sound too. I tried changing cables and disconnecting my overdrive pedal, and it still popped. Finally, I tried another amp to make sure it wasn’t the bass and it sounded fine. Once I narrowed it down to the amp, I noticed that the peak light for the power amp would blink in sync with the popping. The amp has a limiter circuit that I usually keep turned on, but it made the sound whether the circuit was on or off. I usually play with the pre-amp/gain set between 5 and 6 and the main volume at about 8, and it’s clear as a bell. But, I don’t even have to turn it half way up now and it starts the popping thing. It’s still covered under warranty and I have the store’s service plan, so getting it fixed shouldn’t be a problem.
My question is how it happened. I bought a Boss ODB-3 bass overdrive pedal and used it for the first time last week. Could the pedal have blown out the power amp? Although, I tried to adjust the pedal so there was no boost when I switched it on, it does have the ability to boost the signal. Since I’ve already got the main volume on the amp turned up to 8, could the pedal have given it enough boost to blow out the power amp? I’m curious because I’d hate to get the amp fixed and blow it out again.
The amp is a Fender Bassman 200. Bought it new in January. I’m playing a Rickenbacker 4003 through it and the pedal is a Boss ODB-3 Bass Overdrive.
So, did I break this thing myself or is it just “one of those things”?
Mods: If I put this in the wrong forum, I apologize.
Maybe the clipping from the overdrive (distortion) caused the coil in (one of) the speaker to distort or caused a tear in the speaker(s). If your amp has post-amp output jack you could hook it up to some other speakers to see if it’s the speaker(s) or the amp.
Or maybe the volume, tone control knobs, etc… are dirty and have bad contacts within. Take it to a shop that knows these things, they will be able to tell you what it is. I doubt your pedal blew up your amp.
Yeah, ditto on the speakers. You could have a blown one. Definitely try to route the head into another cabinet, if you can match the impedance. Although a distortion pedal shouldn’t cause that.
Thanks for the feedback!
Speaker, eh? I figured it was the amp since the peak/clip light would flicker in sync with the popping. If the speaker was damaged would it cause that light to flicker? I’d try connecting it to another cabinet, but I want to get it back to the store tomorrow and I doubt I’ll have the opportunity before then. The speaker looks fine, but that doesn’t mean it is.
I hope it wasn’t the pedal. I don’t use it too much, but I think it makes all the difference when I do.
It’s hard to say what’s blown. Could the pedal have done it? Under the right (wrong?) circumstances, I guess it could have. Though I must admit I’ve never heard of it happening.
At this point it is futile to speculate what the problem is. When you take the amp in to get fixed, tell them you want to know precisely what the problem was and what parts were replaced (if any). Make sure you insist on this up front, otherwise you may never get any feedback. Relay this information to us and we’ll go from there.
:smack: I missed that in the OP. If the light didn’t flicker before, and it is now, it might be the amp. The speaker wouldn’t cause the light to come on but whatever in the amp is causing the light to come on could also be highlighting a speaker problem. But it could be anywhere. Kind of hard to diagnose without even hearing what the pop sounds like.
Also, try here, they have a discussion board on amps.
So, I got my amp back last Tuesday, and it sounded fine. The guy who fixed it said the board was cracked as a result of vibrations. (This is a solid state combo amp.) I asked if it was likely to happen again. His response was that it wasn’t likely since he soldered it really well. At the time I didn’t give that comment a second thought. Last night, the amp starts popping again, although not as badly as the first time. That’s when I figured out what the soldering was about. I assumed he replaced the cracked board. What he must have done was patch it by soldering all the points along the crack where a printed circuit was broken. I’m taking it to another shop in the area that is a certified Fender service center. I’m going to tell him everything that happened up to this point, and ask if he would replace the broken board rather than patch it. If he won’t, I’m going back to the store I bought the amp from and “requesting” that they take it back or replace it.
I also noticed while inspecting the amp last night, that the fuse was blown. This fuse only protects the piezzo (sp?) horn. The manual says it protects from overdrive, so I guess my pedal is responsible for that. I can adjust the horn level, but I don’t know if that would keep the fuse from blowing.
Speaking of the pedal, should I be running through the amp’s send/return jacks for effects? I’ve been running it instrument to pedal to amp input. Is that wrong?
They should replace the cracked board. Soldering each trace from one side of the crack to the other is bogus–only for total cheapo repairs or boards that are so old you can’t find a replacement.
The blown fuse is because you were getting the pops and from the bad board. Has nothing to do with the overdrive pedal. Ditto the overdrive light–it was because of the cracked board, not the pedal. Watch that light when you get a new board in there–if it’s not flashing, you’re cool. You might be even cooler if it IS flashing. My bass player says “If you don’t have to go up on your toes to adjust the knobs, your gear ain’t piled high enough!”
The pedal is almost certainly designed for instrument level input. Don’t put it in the FX loop–that’s for rack-mount stuff.
I have repaired cracked PCBs by bridging over the crack w/ stranded wire. But:
- I was doing this to my own equipment.
- It was not under warranty.
- I was being cheap.
If this unit is under warranty, the repair should be strictly OEM, which means bridging across a crack is not acceptable…
Well the amp is now at another shop. I spoke to the guy about an hour ago. He says the board itself is not cracked, but the solder attaching one of the components most likely is. He hasn’t found the problem yet, but it is making the popping sound. Apparently, it’s possible to think you’ve found the bad connection and re-solder it, only to find out later that it wasn’t the problem.
I asked him about the blown fuse also. He says those fuses go pretty easily. They’re designed that way because it doesn’t take much to damage those horns. Better to replace the fuse than the horn.