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Ampeg B25 deal advice needed

paparoof

paparoof

Apr 27, 2011
1,296
691
Minneapolis
www.paparoof.com
Disclosures
fEARful koolaid drinker
#1
I have a B25 cab with brand new Eminence Beta 15s in it, sounds like heaven to me. I've been just dying to get the B25 head for it as well, just cause tubes rule and I think it'd be mighty righteous to play through a rig that's as old as I am (give or take a couple years).

Found a pretty beat up B25 head in a local GC. Layout pretty well matches this one with just the two switches on the right side. The lines are blue, but almost entirely rubbed off, can't even see the Ampeg logo anymore
1972AmpegB25B002.gif


Except there's an additional input jack to the left of the standard four input jacks in the picture above. None of the B25 images I can find on the Google show this jack, leading me to believe this is something a user added somewhere down the line.

There's also an extra, empty hole on the back panel, right under the two-prong power outlet, right about where the right side of the yellow sticker is in this photo:
1972AmpegB25B014.gif


Can anyone tell me if this will identify it as a particular series in the model or if this is all after-the-fact re-muddling?

The chassis is pretty wobbly, the metal corners are gone, tolex is in bad shape, it made some fairly wonky sounds and gnarly squealing while the store manager tweaked the knobs as I played. He also got a shock from it while touching it and leaning on a Mesa stack at the same time.

So though it sounded wonderful (when it wasn't squealing or wonking) clearly it's in dire need of some help. The manager looked downright embarrassed by it. The tag said $399 on it, there's no way I would pay that, but I was thinking of offering him a straight up trade for an Ampeg B500DR head (SS, 350@4, all digi front end with four programmable memories accessible by footswitch). I figure if I sold the B500DR outright, I'd end up getting about $250 for it, so that's what I'm essentially offering for the B25. You gotta figure GC will have an easier time getting $400 for my B500DR than they will for this B25.

So.... yes? no? Stupid idea? Run away from a head in such bad shape?
 
#5
It has obviously been modded, and there is no way to no how without going inside it. It should be reversible, with the exception of the cosmetics. The wobbly chassis is normal, it has "shock absorbers", which are likely worn and easily replaced. All B25's have two prong cables, so the shock was just a difference in ground potential, and easily fixed. B25's are great heads, and any 40+ year old amp will require some service. It is overpriced, and I would offer half the asking price, given the unknowns.
 
#6
Well I brought it home.

The best part is, the deal isn't even done yet. Dood said I could have a couple days to mess with it and decide on my own time, then just give him a shout back. So I can still back out if I decide to. I think that's pretty darn mom n' pop for such a huge chain as GC, so kudos to that manager for being so cool.

And my remembery was a little worse than the facts. The tolex ain't SO bad, the metal corners ARE all still there, the wobbly in the chassis is exactly as DMAC stated. It's sitting on little rubber grommets and they actually don't look too bad from what I can see.

I'm about to re-wire my cab for 16 ohms, then I'm gonna plug this bad boy in, fiddle with it long enough to get to know the quirks, then I plan on making a little video for y'all so you have some better info to help me decide just how bad the quirks are.

So if you wouldn't mind standing by....
 
#7
That is very cool for GC. Yep, you definitely want a 16 ohm load for it, although it can be modded to run an 8 ohm load too. Play with it and see how it works for you. I assume it is running stock 7027's, which do sound really good and are still available. It can also be modded to run 6550's for a little more oomph. Good luck and let us know what you think.
 
#8
Well wouldn't ya know it, I can't get it to make any of the wonkyness and squealy sounds. I've had it running for purt-near two hours now and no sign of the badness. In the store it was running through an Ampeg 810 - what's the ohmage on that box? Could that have caused the wonky?

I did get a tiny shock from it while touching my bass strings and also touching some other plugged-in audio equipment on my desk at the same time. Looking at the image of the faceplate on Fliptops.net shows one of the front switches to be a polarity switch. Oh yeah! I remember those from my teenage years. Flipped the switch, touched the same piece of equipment again, no shock. Flipped it back, got a shock, flipped it the last time, no shock. There I fixed it.

I dunno y'all, this thing seems to be working fine.

It sure sounds "tubey" as all hell, but it's not super-articulate and it breaks up REALLY early - like barely at half volume on either channel. Of course it's nowhere near as loud as my other rig through the same cab (Sansamp RPM/Crown XLS 1000) but I understood that going in (1100 watts > 50 watts).

I also understand that no matter what, it should go in for a full service checkup anyway. I have not yet pulled out the chassis to get a look under the hood, but I'm taking photos now and will get some gut shots too. Then I'll slap it all back together and try to make a video.

It IS a B25 by the way - not a B25B. But as my searching here tells me, the heads are identical. The only difference was the cab they were paired with.

Serial number is 106971 - does this mean it's from 1971?

If nothing else, this is a pretty fun way to blow a no-gig Saturday.
 
#11
mmm'kay.

Here's some crappy cell phone video. Audio isn't exactly hi-fi, but you'll get the idea.

http://youtu.be/MUm53eb82l0

(Someone please PM me instructions for embedding the video directly into this thread?)

Main concern at this moment is how easily it breaks up. Should it overdrive this easily/quickly with a passive bass? I like a *little* dirt, but not this much. Is this normal? Are there mods I can make to get a little more clean headroom out of it or is this what a B25 is supposed to act like?

And where the hell is Jimmy? I thought for sure I'd have heard from him by now. Must be workin....
 
#12
Just plug your bass in one of the two open jacks. You'll need to experiment to find which comination of channels works best for you. From what little I know about your speakers, they should do a nice job. I have a '72 B25B with matching 2X15 cab with the opitonal Altec 421A's. What a super nice sound. I've used it just like that on small and medium gigs. With bigger shows, I add a 150 watt RMS Acoustic Control Corporation power amp. No PA support for either set-up. Amazing sound and with the power amp, gets pretty loud.

You'll need to go to the search function for dating info. For much of the production period for these amps, dating is achieved through faceplate colors, features etc. Enjoy. :cool:

I just listened to your clip. As you say, not a quality audio, but it certainly sounds like you have issues somewhere in the head and/or cab. As I mention above, mine is loud enough to stay with drums, guitar and keyboard, keeping in mind that I like lots of bottom, so the bass controls are usually close to maxed.
 
#14
anderbass said:
You'd plug into either one of the other 2, see which one sounds best but it probably wont make any difference.
Click to expand...

Got it - thanks. I'll try that tomorrow. Kids are in bed now, so gotta remain quiet.

anderbass said:
If you insert a bare 1/4" jack into your extension speaker jack, you could safely use an 8 ohm cab.
Click to expand...

Yep I know about that trick, but I won't need that option. The cab has the 4 or 16 ohm switch in place. I bypassed it many years ago but if I keep this head, I think I'll just wire the switch back into place cause I need 16 ohms for this head and I like to run the RPM/XLS1000 setup at 4 ohms so the switch is the perfect solution.

I'll do my own search for the "how to wire up the switch" question. ;)

Gonna get out the screwdriver now and snap some gut shots....
 
#16
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These two tubes only say "7027A USA" on them. Any other ink is long-since worn off.

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Okay, couple questions here. What's the "hum balance" jack intended for? And what's the little screwdriver knobby below that for? Is that where you bias the tubes? Someone please write me a friggin manual!

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#17
You can see here the inside of the additional input jack. If it's a way of doing the jumper thing between the two inputs why do I hear no change when tweaking the knobs on Ch. 1? Looks like a TRS jack, but how do I run that to my bass? ***???

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I would say those look like dynamite sticks to me, but the Government might label me a terrorist - so I won't say it.

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#19
Okay all y'all....

The video plus the images here should give you enough information to either tell me this is a good or bad deal, or at the very least to suggest work that needs to be done. Please go nuts and spew as much info as possible.

I threw in a couple new questions amongst the pictures too....

Really would love to know how to get more clean headroom and crisp highs outta this baby. I know it's possible, I've seen every youtube video there is....

Jimmy - where are you?
 

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