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To fix or scrap - Ampeg b248

C

chadface

Nov 21, 2012
305
574
Southern California
#1
So I recently came upon a ampeg b248 combo in pretty rough shape. For those unfamiliar it has four 8" speakers and a 200 watt amp.

I bought it thinking it would be fun to fix and play with but after digging into it a little I'm not sure it's worth the money to fix. The head does work (had to fix some loose wires) but needs some knobs, a new pot, and a couple of sliders for the eq. Two of the speakers look like they were eaten by a mouse (the leads are gone on one of them and the suspension is damaged on both).

So what do I do? Fix it or scrap it? Anyone think these amps are worth messing with?

I could also put the head in a case and sell off the rest. I don't really need a head...or a combo for that matter.
 
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#2
Pic of the amp in question

Screenshot_20181016-165354.png
 
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#3
The speakers in ampeg amps from the era were not bad. I’ve seen ones where the amp was removed and the cab used as an extension. The amp in a head case would not be worth much. Maybe less than the cost of building the covering the case.

Whether it’s worth fixing or not depends on how much of the work you will do. If you need a practice amp, it could work.
 
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#4
I have a thing for old combo amps that nobody wants. Especially in the 200 watt range. And especially ones without switch turd power supplies

Looks like a beauty to me.

Headcase or change the baffle to a sealed 1x15 or 2x12 since unfortunately the 8" speakers aren't in good shape and wouldn't care to buy 4 new 8" speakers. Cheaper and more sensitivity with larger single driver or pair
 
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#5
BogeyBass said:
I have a thing for old combo amps that nobody wants. Especially in the 200 watt range. And especially ones without switch turd power supplies

Looks like a beauty to me.

Headcase or change the baffle to a sealed 1x15 or 2x12 since unfortunately the 8" speakers aren't in good shape and wouldn't care to buy 4 new 8" speakers. Cheaper and more sensitivity with larger single driver or pair
Click to expand...

Hmmm, I do have a couple of carvin 12's laying around I will have to see if I can make them fit. Thanks for the idea!
 
#6
Hmmm...would I want to fix it up or not? I really don't know. I get the historical value of it, but putting 4 Alpha 8a's in it would be my speaker choice, and while they would smoke in that cab, that's probably $200 right there, not to mention what it would cost for the electronics, and you can't find those sliders anymore, I don't believe. And I didn't like the B2 head enough to care about dropping that kind of scratch to fix it. Love Ampeg but that whole B-series of amps did nothing for me.
 
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#7
If I had it Id fix it up and, depending on how it sounds, either keep it or flip it.
I most likely have the parts it needs to fix it.
And I'd replace the two 8" speakers as those 4x8 cabinets sound pretty good.

What can I say? I love working on amps like that.
 
#8
Think 3 pro and b2 use same part number for the sliders.

Full compass has them

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Also they have various large knob and small knobs so you could possibly find matching knobs. Or just change all of them to ampeg style knobs that work with the shafts in your amp. most likely full potentiometer replacements if you need them.

://Invalid Link Removed
 
#9
BogeyBass said:
Think 3 pro and b2 use same part number for the sliders.

Full compass has them

://Invalid Link Removed

Also they have various large knob and small knobs so you could possibly find matching knobs. Or just change all of them to ampeg style knobs that work with the shafts in your amp. most likely full potentiometer replacements if you need them.

://Invalid Link Removed
Click to expand...
I wouldn't know if those sliders would fit or not, but I guess it's worth a shot for a little over $3.
 
#12
JimmyM said:
I wouldn't know if those sliders would fit or not, but I guess it's worth a shot for a little over $3.
Click to expand...

This is listed as a B2 slider
If you scroll to the description it's a replacement for
  • SVT-3PRO
  • SVT-350H
  • B2
  • B-2R


Ampeg either used 20k or 100k sliders
And the B2 uses 100k sliders

B2 , B2-48 and SVT 350H are the same amplifier.

For the OP you can download the schematic from ampeg support. B2, SVT 350H are similar PDFs the B2-48 files show the 4x8 combo wiring diagram.

For more complete schematic use the B2
Parent directory is here

[Invalid or Expired Link Removed]

If I remember my 350H had small shaft potentiometers and were plastic.

Gain, Bass, treble and ultra mid are all the same pot and value 50k linear, there is 2 different part numbers for 350H head for 50k pot. Both same value , both same spacing. I can't remember if my 350H had center detent. Probably the difference. Or otherwise similar plastic shaft and leads with 50k value

://Invalid Link Removed

Invalid Link Removed
 
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#15
Depends on how much you paid for the amp.
I would fix it if I got it for cheaply and I could use it, or sell it on with some form of small profit. As long as the head works ok.
It's a fairly simple project and not overly expensive unless you go mad with the drivers.
If you can't get the sliders just use the eq pots I had a b2r briefly was an ok amp, a little underpowered but tone wasn't bad. I never bothered using the graphic eq.

As for the drivers just replace the ones that are not working. Need to find ones that will work in that cab of course but I wouldn't go overboard. If you have some other drivers kicking about you could make up another baffle and try it that way.
Then give it a good clean and light cosmetic work.
Probably has a lot of life left in it.
 
#17
BogeyBass said:
This is listed as a B2 slider
If you scroll to the description it's a replacement for
  • SVT-3PRO
  • SVT-350H
  • B2
  • B-2R


Ampeg either used 20k or 100k sliders
And the B2 uses 100k sliders

B2 , B2-48 and SVT 350H are the same amplifier.

For the OP you can download the schematic from ampeg support. B2, SVT 350H are similar PDFs the B2-48 files show the 4x8 combo wiring diagram.

For more complete schematic use the B2
Parent directory is here

[Invalid or Expired Link Removed]

If I remember my 350H had small shaft potentiometers and were plastic.

Gain, Bass, treble and ultra mid are all the same pot and value 50k linear, there is 2 different part numbers for 350H head for 50k pot. Both same value , both same spacing. I can't remember if my 350H had center detent. Probably the difference. Or otherwise similar plastic shaft and leads with 50k value

://Invalid Link Removed

Invalid Link Removed
Click to expand...

You sir (or madam) are amazing. This is very helpful.

I'm going to see if I can fix the drivers on the cheap and take it from there. I might wire up the 2 working speakers to get an idea of how it sounds. It'll be 4 ohms but I won't be using it for long.

Thanks everyone for the comments! Keep em coming!
 
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#18
SLM Electronics 86-127-08

Is the 8" speaker
8444b82a35fa16c9724a5d6a6bee6584.jpg
Seems hard to find
They used a plastic cone with foam surrounds.

High sensitivity, large magnet 8"
Supposedly that cab is 103dB so
Alphas would not be close at all

The made a matching extension cabinet
Ampeg SVT 48HE
When they do pop up they are usually 150 to 200 bucks.

Foam surrounds are notorious for degrading and breaking down. If the voicecoil is ok. You could refoam the surround.... possibly
Not a recone, just a re foam they have generic kits
 
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