smoked the concert bass last night!

[RxJxVx]

about halfway through our first epic voyage last nght, the concert bass did something bad, and by the time the first song was over, the amp was SMOKING.  i immediately disconnected everything, and played the rest of the set using just one 100w bass head, which still sounded great.<P>i had the concert bass powering ONE 4ohm bass cab housing 2 600w eminence speakers.  (by the way does this mean 600w RMS or 1200w?) i was using the same setup i've always used with the amp, but i did add a boss bass limiter enhancer to the effects loop and had discussed the potential for blowing something up just yesterday afternoon.<P>i am hoping one of you amp wizards out there can possibly shed some light on how or why my amp blew up last night.   

[rick.heil]

Well, I don't think it was an impedance problem (Ed could disagree).  Two 600W speakers should handle the Concert Bass just fine.  How far did you turn it up?  Were you running the enhancer extra-hot?  How many gigs have you played that loud with it before?

Hopefully it's something "easy" to fix like a few components in the power section, and you didn't melt the whole thing.

[RxJxVx]

the level was pretty high, maybe about 3 oclock, the threshold was at 12oclock, the enhancer was at probably 9-10 oclock, and the ratio was set to 11 oclock

i really don't think it was an impedance thing.  the cab is wired to 4 ohms which the concert bass should be able to handle safely.  i have used the concert bass at very high volumes before but never with the limiter / enhancer before....hopefully it is something simple, as rick has suggested

[rick.heil]

The impedance thing was just jest, don't worry.  If I remember correctly from the countless times the question has been asked, 4 is considered safe and 2 is pushing it.


Anyways, it could be that something just decided to fail on the night you stuck something new in the signal chain.  Unless your bass sounded radically different, I wouldn't think it would have put too much extra load on the amp.... maybe some pictures of the damage?  Yeah, I'm morbid like that :-p

[RxJxVx]

pics coming soon - i do not own a digital camera - go figure...

[RxJxVx]

after opening up the amp and taking a look inside, it looks like 3 fuses(?) are burnt up pretty badly.  nothing's melted, and i may not be able to post any pics any time soon...

[rick.heil]

Describe these fuses... they may be larger resistors and not fuses.

[JoeArthur]

after opening up the amp and taking a look inside, it looks like 3 fuses(?) are burnt up pretty badly.  nothing's melted, and i may not be able to post any pics any time soon...

Yeah, more than likely resistors. What year concert are we talking about?

[RxJxVx]

fairly small maybe the length of a fingernail and the width of a slim cigarette....the non-burned one was sort of red with 2 yellow stripes.

i BELIEVE the amp is circa 1976 or so...the "inspected / tested" date is not legible on the inside

[rick.heil]

Yes, those would be resistors.

[JoeArthur]

fairly small maybe the length of a fingernail and the width of a slim cigarette....the non-burned one was sort of red with 2 yellow stripes.

i BELIEVE the amp is circa 1976 or so...the "inspected / tested" date is not legible on the inside

So... you are saying that there are 4 of these things... and they look red (i.e. not brown or tan), and they only have 2 yellow stripes?

That doesn't sound like a resistor to me.

No, I need to see a picture. Even basic resistors have at least 3 if not 4 color stripes.

Where are these components located? On the printed circuit board, or off of it? And if it is the printed circuit board, is it the one towards the back (power amp) or the one towards the front with the controls (preamp).

The double yellow bands got me for a resistor. There is no resistor value that would have double yellow bands in this amp.

I need a picture.

[rick.heil]

This is true, Joe, resistors would have a few more bands.  Hmm.

Maybe an older-style cap?  Not sure what size and type were used.

:defers to Joe's expertise:

[RxJxVx]

i will borrow a digital camera and snap a few pics.  i honestly dont remember how many stripes.  it was rather late on a sunday nite

[JoeArthur]

Where's the pics?