Opinions on SWR SS-180 (c.1986)

Discussion in 'Amps [BG]' started by tmsbandman, Feb 12, 2014.


  1. tmsbandman

    tmsbandman

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    Hi all. I bought an SWR SS-180 a few years ago. It's got a tube pre and is from c.1986. It caught my eye because ot goes back to the early SWR days (I believe when Steven Rabe was actually still making them himself.) I Got a great deal on it, and it's strong enough for what I need. I play it though a Working Man 210T. I've been happy with it, though the EQ circuitry is a little unusual. I'd like to know the frequencies and band width of each control. It has Bass and treble, but also Low, 2 mids, and a high. Also-The Aural Enhancer does not seen the same as the "Transparency" control on later SWR gear. My question: Is this amp anything special, or just "so-so." I played a MarkBass combo amp a few days ago and the tone of that blew my socks off. Another post coming about that. Opinions are appreciated.
     
  2. MuthaFunk

    MuthaFunk

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    As you've found out, there's not a lot of info on these heads. It's definitely a Steve Rabe hand built era.

    Is the amp "special"? Well that's really for you to decide. There are SWR fans but they are few and far between. I'm sure some people would like to have one of the first SWR amps made in their collection such as SS-180. Resale on SWR gear as a whole is at an all time low these past couple of years. It seems widely accepted that the build quality is still top notch and many are still keeping their owners happy after 20-25 years of reliable service.

    Many of them were designed to dissipate heat through the chassis which IMO wasn't a great design. Because of this most of the early SWR designs that had power amps in them and were used regularly will likely need new capacitors due to the extreme heat they have been exposed to over the years.

    In other SWR amps the "transparency" control is an upper treble range EQ. I think it's centered around 10Khz but don't quote me on that. The Aural Enhancer is more of a low mid cut and treble and low bass booster. Theres an interesting thread here on TB where folks have modified their SWR products to bypass the Aural Enhancer with very positive results. That thread goes into detail on what the Aural Enhancer actually does if your interested.

    I have done the mod on a few of my SWR pieces and been happy with it.
     
  3. T-Bird

    T-Bird

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    Hi.

    It's only special IMO because it's an early SWR as well.
    A classic indeed, a design that spawned quite a few "upgraded" amps over a few decades.
    I probably won't ever sell the ST220 I was able to buy over a decade after I parted with my SM400.

    You won't be able to send Yor kids through college by selling it, not even have a wet evening in a nice joint, but with a bit of periodical maintenance you should be able to enjoy it for a long long time for what it is.

    IIRC the SS180 shares the same power amp topology with the ST220 and SM400, so periodical biasing of the output devices is required to keep things running smoothly.

    If the periodical biasing is performed, or if the components don't drift that much, the chassis heat sink is more than enough to dissipate the heat.
    IME anyway with both ST220 and SM400.

    Regards
    Sam
     
  4. tmsbandman

    tmsbandman

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    Thanks for the opinions. I'm not necessarily looking to sell it, I was just wondering. I'm just an amateur, but I learned a couple of things. 1-I really thought SWR was more highly regarded (I'm a fan of the preamp section on the newer stuff) and 2-I have no idea what "biasing the output section" is. What is it, and what are the symptoms of it needing to be done? It definitely gets hot. The top gets quite warm. I have a half space below and 1.5 spaces above it in my rack. Prices above it are shallow, so there's plenty of air space.

    So-I'm assuming that keeping the Enhancer all the way off is not the same as bypassing it in the circuitry? Sorry for so many questions. Not much of an amp wiz, as you can tell. I felt proud that I diagnosed and repaired a missing wire that was disabling my effects loop :)
     
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  6. tmsbandman

    tmsbandman

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    MuthaFunk- What an awesome thread! Thanks for telling me about it. I read the whole (11 page) thread, even where it drifted off topic. Apparently I do like "flat" because my EQ settings are pretty much inversions of the built-in tone shaping. I'm going to open mine up and take a look. Definitely interested in the "three position" option. I'm excited about the possibilities. Also very cool to get confirmation that this is actually a hand made Steven Rabe amp. I like gear with a story.
     
  7. Jim C

    Jim C Supporting Member

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    I too have a very early SM400 (before the transparency control although Steve added it (without the silk screen for about $40 back in the day!)
    These amps put out dangerously low frequencies that most cabinets cannot handle.
    An fDeck HPF would fix this although I currently pull all the 35 HZ (quasi parametric) as well as keeping the bass knob at 10:00 and boosting about 120 for bottom and 200 to get the mids back.
    Some day I'll have the time to perform the AE mod with a switch to retain the original design
     
  8. T-Bird

    T-Bird

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    Hi.

    About 20 years ago, yes.

    The decline that finally resulted the Fender swallowing SWR probably took the sharpest edge from the products reputation.

    For most people those old SWR amps are just old, nothing more.
    At the same time, those amps are not old nor rare enough to be considerd "vintage".
    IMO/IME it's mostly the people like me who coudn't afford them back int the day, but are old enough to have seen our idols use and advertise them, who still buy and respect old SWR products.
    Our ranks are diminshing pretty fast though...

    The lack of power has always plagued the product, extending the frequency range onto the low side makes the amps sound weak by comparison to the competition.
    The amp topology Mr. Rabe chose isn't helping much either, if the bias drifts badly, the discretes die, taking the cab(s) with them as well if the speaker fuses have been defeated.

    The pre-section however is pretty much bulletproof, and often it's just the pre that is in use, the power amp(s) is defeated or removed.

    Any SWR amp was also very expensive back in the day, so most of the units have survived, and that is what always brings the price down.

    The symptoms of drifted bias are distortion, cross-over distortion to be exact, and excessive heat.

    Quite warm sounds like it's OK.

    I'm not 100% certain that the SS180 amp board is the same as the ST220 and SM400, heck there may not be a single SS180 in Finland, but Your tech will be able to tell if it is. The biasing procedure itself calls for a 2 Ohm dummy load, a signal generator and an oscilloscope, so usually that's not something a regular user can perform.

    http://mhumhirecords.org/DIYpages/schematics/SWR/Bias.pdf

    Regards
    Sam
     
  9. tmsbandman

    tmsbandman

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    Heh. Describes me perfectly. It suits my needs, though. I am wanting to do the AE bypass. No plans to get rid of it. Thanks for the info, particularly on biasing.
     
  10. Low Class

    Low Class Supporting Member

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    I remember when the SM400 came out and it was about the same time as the Hartke 410 aluminum cabs came out. People would try out this combination in the stores and it would sound incredible, then get em on a gig and were blowing speakers right and left. Hartke had to put out a warning to its dealers to stay away from this rig.
     

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