SWR sm-400 bass head

go for an sm400S if you have the option.

Check out how awesome these guys are.

 

I know the amp extremely well. Back in the mid 80's, I toured with two of them going through four, 15" EV "Vented Midrange" cabinets. I still have one of them. Great, great amps. They would not be my first choice for rock or glam though. They don't have a lot of grunt and growl. They aren't agressive sounding. They are more "refined".

 

Manual: http://support.swramps.com/manuals/pdfs/sm400om.pdf

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It ain't bad. I used to have the SM-500 and played many a 400. Liked them, didn't quite love them, but they're good amps.

I would agree entirely. I did like them, though.

 

Still got the one I got back in '88. Every time I start feeling "meh" about it I crank it up. I can get a good smooth sound out of it. Don't have any volume issues like many people talk about. Of course, I'm not trying to bust ear drums either. It's been quite reliable. A "workhorse".

 

I used to have a 400 way back in the day..I remember that it used to get extremely hot,and the actual body started to rip away from the faceplate while in the rack....It eventually got replaced by an Eden WT-400 (I still have it as a practice/backup amp) which was vastly superior..IMO....I don't miss the SWR at all,but in its day,it was the latest,greatest in new technology.

 

As an owner back in the day of two, I say, because I had and read the owners manual that it's supposed to get hot. The aluminum chassis acts as a heat sink drawing the heat away from components. Very very reliable. Dropped one from the back of a Pathfinder, quite high up, onto 300 yr old cobblestone street. Worked until one of my two had a disconnect of the power cord inside. Coulda been the one that fell out of the Nissan. Was never sure.

Great head. Was boutique small maker. Crank the pre. Reduce treble a little. Master for volume choice. Aural Enhancer 11:00 max use.

 

These amps were the bees knees back in the day. And, they'll still keep up today.

 

I have an SM400s. Still use it, especially if I play outdoors. Run it in bridged mode and through a 15" EV ported speaker 8 ohms cabinet. Sometimes with 2 cabinets. Has 12AX7 in preamp. Has plenty power and as someone pointed out, a refined tone overall. It took me a while to get used to the eclectic EQ controls. They were not intuitive at least not for me. However, after much experimentation, now I can dial in a real good tone for my P-bass. Had to attenuate the extreme lows and bright highs, and find the usable bass region with low mids and mids to get there. its been a workhorse for 2 decades now. A keeper.

 

I really liked mine when I had it, and was an SWR fanboy in general for a couple of decades. Super reliable amps, never had an issue with them whatsoever. +1 to a lot of the points above - they get damn hot, I used to run them with the input gain almost dimed, aural enhancer never past noon, and overall a nice hifi tone that worked excellent for the pop/rock stuff I used to play in the 80s/90s. I wouldn't play one today for a variety of reasons, but the pre-Fender SWRs were quite something in their time.

 

I had a SM400S and it was a nice amp. It really benefited from using an Fdeck HPF3. The lows on the SM400S go so deep that it can cause trouble at loud volumes with speakers. Once the Fdeck was in the chain the extensive onboard EQ was even more useful as I didn't ave to use the lowest band to cut 30Hz out anymore.

It also helped to get louder volumes out my cabs when using the SM400S.

With its clean tone, that amp takes pedals well too.

When buying these amps used there are a couple things to look for:

1. The SM400S was a decent upgrade over the SM400. Not only did it put out an extra 100 watts it also had a much needed upgrade to the heat management inside the amp.

2. Listen to the idle noise, as mentioned, these amps ran hot and capacitors used in them are now coming up on 30 years old. With the whole chassis being designed as the heat sink it in effect raised the operating temperature of every component inside the chassis restricting their lifespan.

If there is significant background noise in that amp that is a good indication that it didn't just sit on a shelf for the last 30 years doing nothing but likely was used exposing all those components to heat.

It will likely need a cap replacement job.

3. These amps have a bias pot that often over the years has drifted or been jarred in transport falling out of someone's NISSAN pathfinder. This will cause the amp to run even hotter. The Bias of both internal amps should be checked by a technician.

The procedure can easily be found online.

One way to tell if it's had its bias thrown out is by popping the top. Starting the amp with the master volume down and waiting 15 min. Then touch each of the two heat sinks inside and see if they are cool or at the most slightly above room temperature. They should both feel the same. If one is hotter than the other, they will need to be checked by a tech.

4. Make sure both amps work before you buy it. I saw a case where a guy bought one of these and the second power amp was removed.

 

As long as your seller didn't own a Nissan Pathfinder, the bias should be fine.

 

Wait! What!?

LOL