The Golden Boy
Fleecy Sweaterologist
Last night I had a show and my SWR SM-900 went into thermal shutdown. Again.
The SM-900 was SWR's "flagship" model. It's very powerful, it's got plenty of headroom, a very controllable EQ, it's light, and it sounds awesome. It's a phenomenally great sounding amp. But it has a habit of "blowing up." It's not like I'm pushing it really hard (bass at 12:00, pre around 11:00, master vol at 9:00) and it's well within it's impedance range (an SWR 2x15 cab in bridged mode). I had issues when I first got the amp, little QC things like mystery screws rattling around in the chassis, improperly wired DI, bad fuse well, bad LED/cold solder joint... So I figured it was just another of it's quirks that needed to be fixed up. I had it in to the authorized tech's shop far too many times- what it came down to (for the overheating problem) is that the air isn't flowing like it should. It's mounted in an SKB rack, as it's designed to be used in a rack, and it would always overheat- sometimes blowing output fuses, sometimes just going into thermal shutdown. In any case, it was a $1200+ amp, and it was completely and totally unreliable.
The amp is designed to passively draw air in the back, force it through the heat sinks towards a grill on the side of the amp. That design doesn't take into account of being used in the confines of a rack case. The wall of the rack is less than an inch from the wall of the amp, and the rack entirely encloses the amp. What that means is that the hot air that is removed from the amp chassis gets recirculated into the amp because most of that hot air stays within the rack. Also keep in mind nothing actively forces or pulls air in or out of the amp chassis- there's a fan in the center of the amp that blows it TOWARDS the grill. As the hot air does go out the heat sinks- because the rack wall is so close there's resistance to the air exiting the chassis and a lot of the hot air doesn't make it out of the chassis and keeps getting heated again.
The tech suggested that I get a fan to either blow air into or remove air from the rack. So I got a fan from Radio Shack and mounted it onto the upper rack rail in the back. It removes the hot air that builds up in the rack. It's done well in the past 5 years or so. The amp has never overheated, blew a fuse or even run hot since then. I used the amp a lot, it was used several times a week for rehearsal, gigged every few weeks until last year. For the past year it sees use about once a week and gigged about once a month.
Last night in the middle of the set, probably an hour and a half in- it just stopped in the middle of a song. I still had power to my power supply, but the amp LEDs were off... As soon as I touched the rack handles I knew what had happened again. It was my first show with this band, and not only was I embarrassed, but absolutely livid that it would happen again. As awesome as this amp could be, I ****ing hate it.
The SWR SM-900. Notice the covered SWR logo- because of their 'awesome' "customer service" I refuse to leave those logos visible and do any sort of advertising for them:
The "guts" of the amp- the long black rectangles are the heat sinks- the fan is just to the right of the heat sinks. The air should be drawn from the vent in the back (at the top of the pic) and then through the heat sinks towards the vent off to the left of the heat sinks. Yeah- That'll work.
And here's the back of the rack, showing the fan I installed into the rack- it's noisy but until yesterday, it did a wonderful job of removing hot air from the rack and keeping the amp cool. Notice the packages of fuses taped to the wall of the rack- just in case.
I don't care that SWR was bought out by Fender. I do hope the "customer service" assclown that handled my stuff lost his job. As long as this amp was working, I was happy enough to deal with it. Because I loved the sound of that amp I put up with the "duds" from that company, I put up with a jackass "customer service" rep, I found a workaround the design issues of the amp. And it's still ****ed.
Friends don't let friends use SWR.
The SM-900 was SWR's "flagship" model. It's very powerful, it's got plenty of headroom, a very controllable EQ, it's light, and it sounds awesome. It's a phenomenally great sounding amp. But it has a habit of "blowing up." It's not like I'm pushing it really hard (bass at 12:00, pre around 11:00, master vol at 9:00) and it's well within it's impedance range (an SWR 2x15 cab in bridged mode). I had issues when I first got the amp, little QC things like mystery screws rattling around in the chassis, improperly wired DI, bad fuse well, bad LED/cold solder joint... So I figured it was just another of it's quirks that needed to be fixed up. I had it in to the authorized tech's shop far too many times- what it came down to (for the overheating problem) is that the air isn't flowing like it should. It's mounted in an SKB rack, as it's designed to be used in a rack, and it would always overheat- sometimes blowing output fuses, sometimes just going into thermal shutdown. In any case, it was a $1200+ amp, and it was completely and totally unreliable.
The amp is designed to passively draw air in the back, force it through the heat sinks towards a grill on the side of the amp. That design doesn't take into account of being used in the confines of a rack case. The wall of the rack is less than an inch from the wall of the amp, and the rack entirely encloses the amp. What that means is that the hot air that is removed from the amp chassis gets recirculated into the amp because most of that hot air stays within the rack. Also keep in mind nothing actively forces or pulls air in or out of the amp chassis- there's a fan in the center of the amp that blows it TOWARDS the grill. As the hot air does go out the heat sinks- because the rack wall is so close there's resistance to the air exiting the chassis and a lot of the hot air doesn't make it out of the chassis and keeps getting heated again.
The tech suggested that I get a fan to either blow air into or remove air from the rack. So I got a fan from Radio Shack and mounted it onto the upper rack rail in the back. It removes the hot air that builds up in the rack. It's done well in the past 5 years or so. The amp has never overheated, blew a fuse or even run hot since then. I used the amp a lot, it was used several times a week for rehearsal, gigged every few weeks until last year. For the past year it sees use about once a week and gigged about once a month.
Last night in the middle of the set, probably an hour and a half in- it just stopped in the middle of a song. I still had power to my power supply, but the amp LEDs were off... As soon as I touched the rack handles I knew what had happened again. It was my first show with this band, and not only was I embarrassed, but absolutely livid that it would happen again. As awesome as this amp could be, I ****ing hate it.
The SWR SM-900. Notice the covered SWR logo- because of their 'awesome' "customer service" I refuse to leave those logos visible and do any sort of advertising for them:
The "guts" of the amp- the long black rectangles are the heat sinks- the fan is just to the right of the heat sinks. The air should be drawn from the vent in the back (at the top of the pic) and then through the heat sinks towards the vent off to the left of the heat sinks. Yeah- That'll work.
And here's the back of the rack, showing the fan I installed into the rack- it's noisy but until yesterday, it did a wonderful job of removing hot air from the rack and keeping the amp cool. Notice the packages of fuses taped to the wall of the rack- just in case.
I don't care that SWR was bought out by Fender. I do hope the "customer service" assclown that handled my stuff lost his job. As long as this amp was working, I was happy enough to deal with it. Because I loved the sound of that amp I put up with the "duds" from that company, I put up with a jackass "customer service" rep, I found a workaround the design issues of the amp. And it's still ****ed.
Friends don't let friends use SWR.
