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L-O-N-G Shot! "Bruce" Amps????

#21
I know where there is one that is still brand new never been out of the store still for sale!

FranF said:
Well, this is nuts but some "older" :meh: fellas here may need to chime in! Anybody remember "Bruce" amps? All I know is Joe Schermie of Three Dog Night had them in '70-72. Most likely a Californy made amp. For the time, it was a respectable setup. The head was just the preamp, ala Acoustic 360, and the cabs had the power module. Joe had the 2 2x15 cabs loaded with Altecs. VERY nice for the time. Thing is, I can't find anything on the web. I'd love to see or copy some pics, catalog info, ads, anything. Whatcha think???
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#24
I picked up an old Bruce Bass Amp and Pre-amp a week ago. Cab # BB215 , pre amp #B 673. Has 2 x 15" Eminence speakers. It was stored for many yrs so was really excited to get and check out. I fired up and played for a bit.I did notice some of the inputs/outputs had been taped off so not to use,someone had removed part of one input that was soldered to the circuit board( must have had an issue with it) so I used the good input and it worked fine.. After firing up a day later it started blowing the main fuse on the amp in the cab. After testing a few components I found 2 of the 6 horizontal transistors on the cab amp are shorted out. i have been trying to find part numbers or a schematic , but no luck; the only markings on the transistors are a "B" and the # 30. That does me no good so far. If anyone knows a source for these parts would love to hear from you. I was playing my 77 Fender Mustang ( fretless "P" pups) thru it and it was sounding so nice...Clean and Loud ! Help I am now using the Bruce cab and powering with my Peavey Classic 212 Hybrid amp and it sounds good but want my Bruce amp back.... Thanks for any info, I have alot of pictures including Gut shots... But I can't find any specs or Transistor part numbers. Any spare parts out there ??
 

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#27
johnnyangel69 said:
I've got a Bruce Amp. It's a B212 model. The "Funk" / Fuzz distortion feature works great. The tremolo is also pretty nice although the reverb just produces feedback. The head and cab are in pretty good condition overall and very clean. I may be consider selling. If anyone is interested let me know.
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In your photos you show a lever to lock the Reverb. I would imagine this is a physical restraint of the Reverb springs when transporting the amp. You mentioned the Reverb just produces feedback. Is this with the lever locked or un-locked?
 
#28
Those trannys look similar to Toshiba 2N3055. If you have the right equipment and can test one of the transistors you have that is operating correctly maybe you can swap in 6 of the modern Toshiba's or something comparable to what you have instead of trying to hunt down a couple of tranny's that are probably extinct by now. They look like TO3 style so it shouldn't be too hard to find what you need to either replace the two that's missing or all six. Also look into what the Acoustic 360 was using in those days which was probably the same part. Hope this helps. The people on the Telecaster forum TDPRI have a thread on Bruce amps also.:cool:
It's a shame that the manufacturer put the upside down "B" over the number 30 on the part rather than have the transistors part number. It's possible that number 30 corresponds to a number on the original schematic.
JohnK who is a member here (who you might want to PM) on another forum speaks of using RCA 2N3055H as replacements in the power section of a Acoustic 370
Acoustic 370 output power vs 470
 
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#29
Clark Dark said:
Those trannys look similar to Toshiba 2N3055. If you have the right equipment and can test one of the transistors you have that is operating correctly maybe you can swap in 6 of the modern Toshiba's or something comparable to what you have instead of trying to hunt down a couple of tranny's that are probably extinct by now. They look like TO3 style so it shouldn't be too hard to find what you need to either replace the two that's missing or all six. Also look into what the Acoustic 360 was using in those days which was probably the same part. Hope this helps. The people on the Telecaster forum TDPRI have a thread on Bruce amps also.:cool:
It's a shame that the manufacturer put the upside down "B" over the number 30 on the part rather than have the transistors part number. It's possible that number 30 corresponds to a number on the original schematic.
JohnK who is a member here (who you might want to PM) on another forum speaks of using RCA 2N3055H as replacements in the power section of a Acoustic 370
Acoustic 370 output power vs 470
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Thank You Clark ! Much appreciated bro !
 
#33
I have a Bruce 100 watt Bass Amp setup with the Preamp, I am looking for info and maybe some parts, Anyone know where to find ? My amp in the cap just blows fuses, I replaced all the transistors with a set of 2N3055's as 2 of the originals were shorted out. Thought that was my problem with the amp blowing fuse as soon as switched on, but not so. May
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be a shorted capacitor ? So time to test and change them out, has anyone heard of a transformer causing this fuse-blowing issue ? Thanks
 
#34
In 1969 my band, SPECTRUM, opened for FRIJID PINK in Virginia Beach. They had Bruce Amps and invited us to use them. The bass amp sounded great. The guitar amp, which I used, sounded great too especially considering that it was a solid state amp. It was LOUD and had a nice tone. I was using a Gibson Les Paul Custom. I would say that the closest comparison for amps back then would be ACOUSTIC Amps, just louder and sounded better. We used their drums too. Go to deanelliskohler.com then click "bands" then click "Spectrum" and there are a few pictures.
 
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#36
Mustangmark said:
I have a Bruce 100 watt Bass Amp setup with the Preamp, I am looking for info and maybe some parts, Anyone know where to find ? My amp in the cap just blows fuses, I replaced all the transistors with a set of 2N3055's as 2 of the originals were shorted out. Thought that was my problem with the amp blowing fuse as soon as switched on, but not so. MayView attachment 919631 be a shorted capacitor ? So time to test and change them out, has anyone heard of a transformer causing this fuse-blowing issue ? Thanks
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I would definitely replace the caps and I would also replace the rectifiers.
 
#38
agedhorse said:
Why?

Proper troubleshooting techniques will identify the failed components better than just guessing.
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Not only better than, also faster than.

Enough guesses usually results in more than just the original problem. Troubleshooting 2 problem is not twice as hard, it's 10 x as hard. Then failures induced by soldering rather than natural failures can compound the situation right to the dumpster.

I have an amp in my basement that's probably headed for amp hell thanks to someone guessing. They also wrapped the fuse in foil and "upgraded" hot/burning resistors to highe wattage so they could make even more smoke and fire! (Not that anyone would do that here... Just a worst case example... I hope.)
 
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#39
Hello Folks! I just joined talkbass, specifically to get some more information about a bass cabinet I just found named "Bruce" lol

I have found very little information about Bruce Amplifiers from a technical standpoint... from what I read here and on this locked thread on a Telecaster forum: Invalid Link Removed these cabinets had some type of powered units in them as well as the amplifier head... can someone clarify this?

The cabinet is in pretty rough shape, but is still solid and heavy as hell. There are two very large speaker with huge magnets in there, but there are no other electronics, and there are two rectangular gaps, one big one vertical on the right, one small horizontal on the left bottom, where it would make sense for something to go. Someone has wired what actually appears to be an instrument cable (!) to the red and black wires, so theoretically they were driving these speakers with some other amp, if these things did have on-board power originally.

I am nervous about testing the speakers with that setup! So how can one test these speakers to see if they are working?

Then there is what to do with it... if these are historic amps, it seems wasteful to use the parts for a custom build if someone is restoring these, but are the speakers and a beat up cabinet useful?

Any thoughts or suggestions would be very welcome. Thanks!

p.s. I will take some pics asap.
 

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