Hey everyone, I have a Sunn Coliseum 300 that just died. I just finished practice (during which there weren't any issues with the amp) and was noodling around when it happened. There was a popping noise, and then no sound. The amp turns on and the fan comes on, and the clip and compressor indicator lights stay on. None of the knobs or buttons do anything. I did all of the obvious stuff - plugging straight into the amp and switching out cables, cabs, etc. and no luck. I didn't mess with the fuse b/c I assumed if it was the fuse the amp wouldn't turn on at all (I could be wrong about this, and I'll take a look anyways). The amp was hooked up to two cabs showing a 2 ohm load (which the amp is rated for) and was also biamped into a guitar combo using the built in crossover. Being an older amp I always worry when something goes wrong because it would be hard to replace.Can any of you amp guys give me an idea how serious this might be? Thanks for the help.
Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
Amp just died...
- Thread starter Battlemode
- Start date
I'd be curious as to exactly what you mean about the guitar amp being connected, as well as a 2 ohm load, but essentially, unless you are an amp tech, that's what you need. They will have the tools and diagnostic know how to get you up and running in no time.
The amp has a crossover that let's you send the highs / lows to separate amps or effects if desired. I run the highs to a guitar amp. By two ohm load I just meant that it was hooked up to two four ohm cabs, resulting in a 2 ohm load.
So, 2 4 ohm bass cabs off the low side, and then from the high side, into a guitar amp? I think you may be missing something, and have gone well below 2 ohms, or possibly, running a speaker OUT into another amplifier, which is also bad. Explain exactly what is hooked up, and from exactly which OUTputs and INputs.
The amp has separate effects loops for the high and low sides. You can either run separate effects for each freq range, or use the send from either loop to feed another amp. I'm using the send from the high effects loop to feed the guitar amp. The only connections using the speaker outs are to the two four ohm cabs.
I'm not sure that amp is really rated to run into a 2 ohm load. When you combine two 4 ohm cabs in parallel, the result is a 2 ohm load which is brutal on amps.
On the rear panel of the amp it says 2 ohm minimum, but I understand the sentiment - what it says and what its really capable of could he 2 different things. However, this is a setup I've used at shows for the past 5 or so years without any issues (I usually practice with one cab).
Hi.
In my extremely limited knowledge on Sunn amps, I'd guess that the power amp fuse blew.
As of why it blew, that's for the tech to find out.
Fuses, being mechanical devices with a mass, in nature do have tendency to break down from mere fatigue. That's the reason most of the touring techs I know of, periodically replace the fuses for the amps riding in non-shockmount cases. A year in the hands of roadies and stage personnel, something that fragile is bound to break up at some (inconvenient) point.
OTOH, Your problem might be in the PS section as well since the pre-amp outs don't work.
Tech time gets my vote.
Just replacing any fuses You might find inside the chassis might work, but in that case make sure that the fuse is exactly same as the markings on the PCB.
Regards
Sam
In my extremely limited knowledge on Sunn amps, I'd guess that the power amp fuse blew.
As of why it blew, that's for the tech to find out.
Fuses, being mechanical devices with a mass, in nature do have tendency to break down from mere fatigue. That's the reason most of the touring techs I know of, periodically replace the fuses for the amps riding in non-shockmount cases. A year in the hands of roadies and stage personnel, something that fragile is bound to break up at some (inconvenient) point.
OTOH, Your problem might be in the PS section as well since the pre-amp outs don't work.
Tech time gets my vote.
Just replacing any fuses You might find inside the chassis might work, but in that case make sure that the fuse is exactly same as the markings on the PCB.
Regards
Sam
This might be a dumb question, but could it be fuse if the amp still turns on? I thought that was something to check if the amp didn't power on.
Hi.
Usually only the mains fuse -which is the very first component in the power supply chain in the equipment, by law- is user replaceable on the back panel, sometimes the speaker fuses (SWR), but that doesn't mean there isn't additional fuses inside the chassis.
Their location is chosen because quite often when those fuses blow, there's something seriously wrong with the circuit. With the usual "No user serviceable parts inside", it's assumed that whoever digs in, knows what they're doing
.
Hopefully in Your case there was one in there, and it protected the circuit as it was designed to do.
Regards
Sam
Usually only the mains fuse -which is the very first component in the power supply chain in the equipment, by law- is user replaceable on the back panel, sometimes the speaker fuses (SWR), but that doesn't mean there isn't additional fuses inside the chassis.
Their location is chosen because quite often when those fuses blow, there's something seriously wrong with the circuit. With the usual "No user serviceable parts inside", it's assumed that whoever digs in, knows what they're doing
.Hopefully in Your case there was one in there, and it protected the circuit as it was designed to do.
Regards
Sam
