Re: New (bass) amp.....need help.
Benjy_26 said:
I saw a guy here in town with a 900 watt SWR rig. He was using four 10's and a pair of 15's. Crushing sound with the active jazz and Stingray he was using. I forget the model, but definately check into SWR.
DON'T bother with the SWR. I've got the SM-900. I've had problems with it from day one- and I opened the box from the factory. The only reason I still have it is because I'd take a bath from selling it and I really don't have the expendable cash. When I get the cash it'll probably be the new 1200w Eden or the Mesa Big Block 750.
What's my bitch with SWR?
Let's just talk about the amp first... Here's the guts of the amp:
The front is to the left. My main problem is the air flow in the amp. The heat sinks are the long rectangular pieces. Fresh air is passively drawn in through the grate in the back, then the fan actively blows air through the heat sinks towards the grate just visible at the top of the pic. What's wrong with that? First, notice there's a gap between the heat sinks and the chassis wall where the grate is. So some hot air is going to recirulate into the amp. Then remember that nothing is forcing fresh air into the amp, it's just being drawn in, but some of that hot air is staying in the amp, so air isn't necessarily circulating in and out of the amp. Now remember the amp is also rack mounted. The rack wall is less than half an inch from the outer wall of the chassis- again, causing resistance to the hot air exiting the amp, keeping more hot air inside the amp. Then again, taking the rack into account, the hot air that
is expelled through the amp is in the rack case, and THAT is the air that gets recirculated back into the amp.
Do you see that problem? The amp heats all this air, that hot air can't cool off the amp- and if it makes it out of the amp, a lot of it get recycled back into the amp because the hot air is inside the rack.
These days I run the amp with a 4 ohm 2x15 in bridged mode- the amp is working hard, but
well within it's limits. It kept overheating, going into thermal shutdown and blowing output fuses. That's a serious reliability problem. Why am I still using this amp? I was able to figure out that if you draw the hot air out of the rack, fresh air can get into the amp.
I ended up drilling two holes in the upper rack rail and mounting a fan, and hooking that up to my power supply.
It's much more reliable now, and the fan is a good idea anyway, regardless of any amp in a rack, but it is kinda loud. The amp sounds great, I've got loads of headroom and a lot of nut shaking thunder- but it's not worth the headaches I've had with SWR amps.
Other problems I had during the warranty period, the DI was wired incorrectly, one of the fuse wells was defective, either the power LED was bad or it was a cold solder joint, there was a mystery loose screw floating around inside the amp when I first unboxed it... This is a "pre Fender" amp.
I also had another SWR, the Bass 750- that's the amp that really got me hating SWR, but for some reason I still had faith in the company's products- that's why I bought another SWR amp- that and the hella deal I got on it.
My understanding of the Big Block is that it's pretty much the M-Pulse 600 on steroids. I've messed with the M-Pulse a lot, and played with the Big Block in stores- that would probably be what I'd shoot for.
