Sunn Coliseum slave questions

[sunnmetal]

Hey dudes, I runn a Beta Lead 4x10 combo through a Coliseum slave Into a 4x12 with no problem at all. I recently picked up a matching 4x12 and was running that pretty well for a few days until i really turned the volume up on the Beta and the slave stopped working. I am unsure if the circut breaker tripped cause i clicked it a few times and it didn't fix the issue. Well I opened it up and the fuses were blown. (the ones i found in there were 8 Amps 125 volts fast breaks) Thinking these may not be the correct fuses i threw in some my beta takes. (12a 125v slo blos) Snapped snapped and snapped again. I threw in some 10a 250v the gauge was much thicker then the slo blos for the beta. It started smoking. With one cab. I bought the fuses i found in there and ran it pretty hard with one cab for about ten minutes and it seems better but it just didnt blow. Am I not using the input sensitivity Knob correctly? To the best of my knowledge the cabs should be running at about 2 ohms and from digging around on here it seems that what i am throwing at it should be noproblem. I was running the cabs out of both the outputs on the slave. Opinions? Ideas? Thanks DJ

[Isaac]

Basic rule on fuses from when I was in the Navy is that you get to replace them once. If they blow again, time to start troubleshooting.

First thing you did wrong was to think that they might not be the correct fuses. Don't guess where fuses are concerned. If you think they're not right, find out, but simply going ahead and replacing them with a higher value risks destroying your equipment. This schematic calls for two 10 amp slo-blo fuses: http://richbriere.com/?page_id=18. It might be the same as your slave. Is there an indication at the fuse holders as to what the correct value is?

Sunn Coliseum power amps were rated for 2 ohm use. I don't recall ever seeing anything that said they weren't good for it, as I have about the Concert amps. But from your description, it sounds as though it runs all right with a 4 ohm load, but not at 2 ohms. Is this correct? Also, you mentioned smoke. Smoke is bad. Even if the component(s) that smoked didn't die, it (they) was probably compromised, and should be replaced. Likely it will fail sooner rather than later.

There are several possible causes for your blown fuses. The amp should be evaluated by a competent technician.

[sunnmetal]

Yea it seemed to run OK with the 4ohm load. Do you know what the particular use for the input sensitive knob is? Besides it clearly controlling the volume? I just found some actual schematics for the slave and they are 10amp fuses. I know it is not a good thing to guess on things like that but I was right! lol. As for a tech to poke around.... I'm not sure if there is anyone I would trust to be qualified in my area.

[Isaac]

The use of the input sensitivity knob is to adjust the input sensitivity. Think of it as a master volume.

More technically, the idea is to match the input sensitivity of the slave to the output of the preamp, such that the full scale output of the preamp will drive the slave to full output, but not overdrive it. In practice, it's not uncommon to set the sensitivity higher, so that you get more output for a given input, at the risk of  a little distortion.