Ampeg BA115 Cutting Out--Jerrold HELP!!!

Jeff In Vegas · #1 02-07-2013, 02:04 PM

I am pretty sure I have figured out the problem with my little BA115, a LOUD tech support person said that this amp has trouble with active basses, and that there is some sort of overload protection in the pre-amp circuit. Of course he couldn't be completely sure, he is available by phone---smile. I am assuming some sort of bi-metal thermistor, but couldn't spot it on the PC board. His fix was to use the -15 input, but anyone who owns this amp knows this input seems to cut all the guts out of the tone, for some reason. I thought initially it was the normalling on the headphone jack, and considered just soldering them together as I never use that, but his explanation makes some sense. My last bassist had a P-bass, and it NEVER had this problem, maybe I should insist upon my new bassist dumping that ugly Alembic and go back to the future/past........

kleinenenten · #2 02-07-2013, 02:12 PM

Quote:

Originally Posted by Jeff In Vegas

I am pretty sure I have figured out the problem with my little BA115, a LOUD tech support person said that this amp has trouble with active basses, and that there is some sort of overload protection in the pre-amp circuit. Of course he couldn't be completely sure, he is available by phone---smile. I am assuming some sort of bi-metal thermistor, but couldn't spot it on the PC board. His fix was to use the -15 input, but anyone who owns this amp knows this input seems to cut all the guts out of the tone, for some reason. I thought initially it was the normalling on the headphone jack, and considered just soldering them together as I never use that, but his explanation makes some sense. My last bassist had a P-bass, and it NEVER had this problem, maybe I should insist upon my new bassist dumping that ugly Alembic and go back to the future/past........

I've had that amp for ten years, up until last week when I traded up. I only used actives on it, and never had a single instance of it cutting out, and I was pushing it HARD the last few months, even using the non-padded input with my active basses for extra volume to compete with a full band. I don't think actives are the problem here, as I NEVER had it cut out. I did have the piezo tweeter start hissing, so I disconnected that, but otherwise, this amp took everything I threw at it like a champ. And I threw a lot at it, being my first decent amp and all while learning. I also have no idea about what you mean the padded input guts the tone. Mine sounded great, and terrible non-padded. It was just loud and distorted unpadded. Anyway, good luck figuring it out!

Jerrold Tiers · #3 02-07-2013, 06:08 PM

I have no clue what the overload protection comment was about... that amp is very simple, and hasn't got any such thing. just some diodes to prevent REALLY strong signals from damaging stuff

It has a fairly simple power amp limiter, but I am not sure what you mean by "cutting out".

When does it happen? How long is it "out"? What do you do just before/as it happens that might affect it?

Jeff In Vegas · #4 02-08-2013, 12:12 AM

Okay, after a few songs, with my new bassist with active basses, the amp cuts out. No audio, although the power light is still on. After a few minutes, it works again, and then it cuts out. Switching to the padded input (-15) doesn't seem to help. I had a similar problem with a vintage Fender Princeton Reverb that I had installed a JBL speaker lifted from one of my Twin Reverbs, which after a lot of headaches by a local tech turned out to be a faulty voice coil, but I just can't believe that lightning of that rarity could strike again. I took the amp apart, and inspected the headphone normalling, and here in the desert corrosion is non-existent, and the contacts seem to have good spring tension and look to be fine. I plugged a guitar into the unpadded input, played it as loud as I could stand, and couldn't replicate the problem, but I know as soon as we rehearse tomorrow the active basses will cause the problem to re-occur. And of course, if I take it to one of our local Vegas techs, I will be unable to replicate the problem, they will check it out, find nothing wrong, because that is always the way with ghosts in the machine.......

Jeff In Vegas · #5 02-08-2013, 12:56 AM

As a side note, I paid a C-note for the amp, and am not that interested in having some greedy tech (or you, Jerrold) eat up a lot of time and money fixing it. It will certainly pass muster as trade bait at the local Guitar Walmart (as a former associate I am aware of their cursory pre-trade inspection). But the amp is perfect for my application as a rehearsal tool, reducing the schlepping into my house, so any ideas you have are much appreciated. As for LOUD, I hold their customer service blameless, even if the very nice person I spoke to was unaware of some pretty well-known bugaboos in their Crate Vintage Club 50 watt guitar combos. I do find it ironic that everything I own produced in the fifties and sixties still works fine, and the mic cords I bought last month have already failed....smile....JJ

Jerrold Tiers · #6 02-08-2013, 06:50 AM

If it ONLY happens with active basses, and maybe only with some of them, it could be related to some sort of DC offset affecting the input. Especially if it distorts a bit before cutting out.

Check all the components around the inputs for good solder, and to be sure they are all still working.

DCrippa · #7 02-21-2013, 08:58 AM

Well I too have a BA-115 exhibiting the same problems - it's been happening for a long time - I got so frustrated with the amp that I just put it aside and forgot about it... unfortunately I waited too long to hit up GC for warranty now I've contacted the manufacturer so we'll see... but same deal - any transient type signal (ie slap or hard hit) will cause what seems like a limiter & overload protection to cut on and remain on - while the unit still has power... powering it down for a long time and then turning it on again *sometimes brings it back to functioning state - but the first bit of input to the amp can cause it to go back to it's non-functioning state... pissed as I barely even used this amp and have never gigged with it... Feel as if I threw away $500 should have just gotten the Fender rumble.

Jerrold Tiers · #8 02-21-2013, 06:48 PM

That's not normal, and any decent technician should be able to find the problem.

I have a couple crazy ideas about possible faults that could cause that, but they are just speculation.

DCrippa · #9 02-22-2013, 08:28 AM

I'm all ears and willing to tear into it since the warranty is void - have a soldering iron comfortable with that - can read schematics and troubleshoot. Don't have an oscilloscope though.

When I have time I'll check the solder connections. Hope it's something simple like that.

Will also try padding / using the -15 input and see if there's any difference.

Off topic though - my friend got the Fender Rumble and for those in the same predicament looking for a viable alternative check it out - it rocks.

StephenJF · #10 02-22-2013, 10:59 AM

My BA115 would cut out if I wiggled the input cord. I removed the chassis for a look inside. Noted the jack was soldered directly to the PCB. The solder job looked jood. So I figured it was Florida corrosion. A few squirts of contact cleaner and repeatedly inserting/removing the cord did the trick. No more cutting out. I play a passive Jazz bass.