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

[jbakervt]

I'd imagine their value is greatly diminished without the amp inside. I'm still looking for an intact working one. ;-)

My first thought was to wire it correctly, see if the speakers work and find some amp head to pair with it.

Do you happen to know what kind of power can these speakers handle?

 

[FranF]

If they're the stock Eminence units, probably 100-150 w max.

 

[Paul Cassone]

Why?

Proper troubleshooting techniques will identify the failed components better than just guessing.

I wouldn't trust caps from 1968. When they go they take other things with them.

 

[Paul Cassone]

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.)

So you think that caps from 1968 are fine? I agree with troubleshooting. Why don't you describe how you'd do it?

 

[agedhorse]

I wouldn't trust caps from 1968. When they go they take other things with them.

I wouldn't recommend just replacing parts that don't test bad until you are sure the actual problems are fixed first.

I have several pieces from that vintage all original with no issues. Just because it's old doesn't mean it's bad

 

[Paul Cassone]

I wouldn't recommend just replacing parts that don't test bad until you are sure the actual problems are fixed first.

I have several pieces from that vintage all original with no issues. Just because it's old doesn't mean it's bad

Yes, you're right. I have older equipment like that too - but I wouldn't gig with it that way!

 

[jbefumo]

I had one of their guitar amps back in the late 1960s, built-in fuzz and everything. Traded a lovely, portable Epiphone tube amp (don't recall the model, but I think it was a 2X10") because I HAD to have something big and ungainly to lug through the streets of Brooklyn, since I didn't have a car. Made sense at the time.

 

[Paul Cassone]

So back the tech stuff -- what about those mystery modules and transistors marked with B. Any more info that any of the folks that built them (Jan) can tell us? Please?

 

[agedhorse]

Is there a problem with them? If not, leave them be...

 

[BogeyBass]

I think its more curiosity thing. Not knowing exactly what they are. Remember old dan electros having early ic type packages in them. Think was module for tremolo or all in one package made for tone controls. Wish could remember the part name

 

[Dirt Rhodes]

Here's a few pics inside 2 channel preamp
Head. This is not the bass head

 

[Bob_Ross]

Whoa! What happens when you turn up the "Funk" knob?

 

[Dirt Rhodes]

Sealed op amps?
I can not believe no one has cracked
1 open to see what's inside
And reverse engineer one

 

[Bob_Ross]

Anybody remember "Bruce" amps? All I know is Joe Schermie of Three Dog Night had them in '70-72.

Wow, I've been wondering about those amps pictured on the back of the Naturally album jacket for 48 years!!! TB FTW!

 

[Dirt Rhodes]

Ahhh the funk Knob
Let's just say it gets really Funky
Naw it's (from what I've read) what they called Fuzz before it was called fuzz.
Good ole fashion distortion
Pots are dated 2nd week 1968 CTS
I just purchased it on vacation in Colorado
at pawn shop and only quickly tested it
With dodgey cords and piggy backed thru
Preamped acoustic combo amp. The funk
Sounded similar to my old little big muff I
Had in late 70s

 

[agedhorse]

They may not be potted op-amps, they could be a variety of other things inside them.

 

[BassmanPaul]

They may not be potted op-amps, they could be a variety of other things inside them.

Agreed. Back in the day HeathKit and Dynaco had assemblies to make construction of their kits easier. You just had to follow the pictorials to position them correctly.

 

[FranF]

Very cool. Great pics!

 

[agedhorse]

Yes, Heath even had IF filters for their TV sets inside modules.

I've modularized things like DSPs, multiband VCAs, power amp driver circuits and PWM control circuits too.

 

[RichieC]

I believe the Doors used Bruce amps early on. I personally used one back in the late 60's at a jam session/audition. It was a strange setup for me at the time being used to Fender heads and cabs. With the Bruce setup you could plug directly into the cab with your bass working volume, bass, and treble from the instrument. I liked the tone and volume I got using a Gibson Eb3 - so did my band mates. The cab had 2 15" speakers and over 100 watts RMS and you plugged into the bottom of the cab where there was (?) a pre-amp. At least that's what the owner told me.