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SWR SM-400 questions

Discussion in 'Amps and Cabs [BG]' started by babuska, Nov 14, 2005.


  1. babuska

    babuska

    Nov 14, 2005
    Finland
    Hi all. I´m a new member here, and I´m not a native english speaker(I´m from Finland, North-Europe), so forgive, if my english is not perfect(and I know that it is not!).
    I´m a guitarist, and not very familiar with bass gear, but since my wife plays bass in our metal oriented band, and her english is even worse than mine, I have to post here.
    So, some time ago we bought an used SWR SM-400 head, I think that it´s a -91 model, the seller said so. I want to know is it possible to use it, for recording purposes, without connecting it to a cabinet? As you know, most of the amp manufacturers warns that you should not use their amps, without connecting it to a speakers.
    I noticed a mention on a SWRs websites, that it´s possible to use their heads, without a cabinet, via D.I output. Is this true also with the SM-400?
    Also, what means "underpowering"? I have heard that underpowering could damage your cab. We are going to buy an 8ohm Avatar 410Neo for SM-400, is it underpowering, since Avatar can handle 1200 watts, and SM-400 is 400 watts head? :help:
     
  2. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    If the SM-400 has a switch to turn your speaker off, then yes, you can use it as a DI without a cab as long as the speaker switch is off. As for underpowering, I don't think you're in any danger.
     
  3. Tim1

    Tim1

    Sep 9, 2005
    New Zealand
    The SM400 is a great head. You can use it as a preamp only, or as was intended straight into your Avatar 410. Either way you will do no damage, as it can be used as a preamp only and therefore must have a dummy load built into its design.
     
  4. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Hi there! Welcome to TalkBass!

    We forgive you for being a guitarist and applaud you for helping your wife.

    I used to own an SM-400 but never used the d.i without a cab attached.

    I also checked out the website and found this.

    And I quote "The only condition you should be aware of is if one or more of the power amplifiers in your unit becomes "over biased." This condition can be recognized by turning your amplifier on and letting it sit without speakers plugged in and without playing it. If, under these conditions, your unit becomes quite warm, it may be over biased. This situation should be attended to and can be easily remedied in about 15 minutes by a service tech. A power amp can become over biased through continuous vibration or by any large jolt received in shipping, etc."

    This implies to me that you can but I could be wrong. The risk is yours to take. :)

    I found that quote here.

    It is at the end of the article.

    The only danger you have in underpowering a speaker is that you might try to compensate for a lack in stage volume by turning up the master volume so high that the power amp distorts. This causes heat dissipation issues when taken to the extreme.

    If you have to turn up that high then it is time for a higher powered amp, higher powered speakers, more speakers or any combination of the three.

    :D

    Joe.
     
  5. babuska

    babuska

    Nov 14, 2005
    Finland
    It has no switch to turn speaker off, how could it be possible? It´s a head, not a combo.
    Tim1: are you sure that there is a dummy load within the design?
    Lowtonejoe: thanks, my wife liked your comments :).
    I´m still not sure can I try it without a cabinet :meh:.
     
  6. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Your welcome. :)

    Hmmm...well, if worst comes to worst you can always give them a call.

    Phone: (480) 596-9690

    But I bet as long as you keep an eye on the temperature of the unit it will be fine. I would take the risk but that's the way I am.

    :D

    Joe.

    EDIT:Also about the speaker switch, Eden heads have this design, others may also.
     
  7. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Ya, I just got a look at the front panel of an SM-400 and it doesn't have a speaker switch, so you probably shouldn't use it without a speaker or a dummy load. You can buy or make dummy loads, though. I don't know a whole lot about it, but I've heard of people using homemade dummy loads to use their amp's DI without plugging in a speaker. Sounds like work to me. I'd rather just plug in a speaker and turn it down all the way. Then again, lugging a speaker around is work, too.
     
  8. Generally solid-state amps (like the SM-400) can be run without a speaker, without any problems. I do this all of the time with my Eden WT-500.

    From the SWR FAQ:

    Q: Can I run my amp without any speaker cabinets connected to it?
    A: Yes. All SWR amplifiers can be used for recording purposes using only the XLR record out and without speakers attached to the speaker jacks.


    To get maximum performance from both amp and speaker, you might want to run the SM-400 bridged into the 4x10". Bridging will give you the most headroom.
     
  9. babuska

    babuska

    Nov 14, 2005
    Finland
    Thanks guys! I try it immediately, I will share my experiences, after I have tried. Again, thanks a lot :)!
     
  10. Welcome to TalkBass, babuska!

    After my first amp, a modest Peavey combo, I played through a 15" Trace combo for a while. It was decent but I'll never forget when I finally got my first "real" rig: an SM-400S and a Goliath I. I can honestly say that I was 'raised' on that tone and it's no doubt a big part of my reference when I evaluate other gear, despite the fact that it's no longer my main amp. Later I bought an early SM-900 but it didn't seem as loud or have any of the 400's magic. I use the SM-400 to this day and I don't think I'll ever sell it. I've since sold the Goliath but the 400 will always have a special place in my heart.

    IIRC, the SM-220 and 400 were based on the chassis (and preamp?) of a bass preamp that was originally offered by GrooveTubes. A buddy of mine had one of these early preamps and it had all the sweetness I had come to cherish in the 400. Whether SWR ended up using GT's preamp is unknown but I like them both regardless!

    I will echo that it's perfectly safe to run it without a load. I've used it for years as a standalone DI with no problems. Apparently some SWR amps, mine included, readily reflect the quality of the grounding and power in the facility through the DI. I can sometimes get a loud buzz at one place and it will be dead quiet at another. It's never been much of an issue in most studios because they usually have pretty clean power. The issues were almost always at live venues; a set of lights on the same circuit as the stage outlets or inadequate grounding.

    I also used it at a Monday night jam for eight years and boy do I love that limiter!! That thing has saved my speakers sooooo many times! I still can't believe it but there was only about one other bassist in town at the time that knew how to properly use an amplifier! I'd have to go up and set the amp for every bassist to make sure they didn't break anything. There were a few jerks who would "soundcheck" for me with their bass real low and then as soon as I'd leave the stage they'd turn it all the way up, in the hope that they could get louder than I'd let them. Hahaha. Nice try.

    The limiter also prevented me from clipping the amp when it was pushing multiple cabs (ie. "underpowered"). Did I mention I found the limiter useful?

    Brad
     
  11. vision

    vision It's all about the groove! Supporting Member

    Feb 25, 2005
    Ann Arbor, MI
    swr actually made the groovetubes preamp for them (the shops were across the street from one another iirc.) so yes, the sm400 and st220 preamps are exactly the same as the original gt preamp...
     
  12. babuska

    babuska

    Nov 14, 2005
    Finland
    Thanks Brad, this helped a lot, I tried it without a cab. Me and my wife had a small session here, in our home studio. Previously we used a Pod for bass tracks, and I have never been a great fan of Pods. I have always found out a Bass Pod somehow unsatisfying.
    What a huge difference between SM-400 and a Pod! Even without a cabinet the sound was so articulated and clear. No dead spots, no boom spots, even with passive bass(Gibson T-bird).
    I also tried it with my guitars, and with high output humbuckers, it was surprisingly good, I could even get out some preamp distortion from it.

    So, limiter helps with this underpowering issue, right? We are still waiting our Avatar 410Neo, I hope it is a good cabinet for SM-400. One reason why we decided to buy a 410Neo is that it should be a good choice for a fivestringer. When we bought the SWR, the previous owner(he didn´t know about this D.I issue) played it with a Spector fivestringer, through Glockenklang cabinet, and I have never heard better low B. It sounded like Jason Newsted on a "Enter Sandman"!
     
  13. Ah, thanks for clarifying that!
     
  14. One thing I forgot to ask.....is yours a mono or stereo model? The stereo model is designated by an added "S" at the end of the model number (ie. SM-400S). Just curious.

    In regard to pushing multiple hi-wattage cabs I found the limiter helpful to some extent. It won't help you in the situations where you're vastly underpowered but with most of my cabs and scenarios I encountered, I never needed it (except, of course, for what was mentioned earlier). The limiter has a fairly hard "knee" so once it engages, it squeezes pretty hard. It alters the tone so much that, anymore, I don't use it unless it's absolutely necessary. I have used the 400 with an Ampeg 810, Accu Tri112+Bag End S15X-D, Accu El Whappo and a Mesa/Boogie 610R all with good results. Only when I played the Ampeg or the Mesa outdoors, without PA, did I ever have to engage the limiter.

    Yeah, I'm not much of a fan of the Pods myself, either. I'll take my Radial JDI box over a Pod any day! Not to say that they're useless. Far from it, actually. It should sound great with the new Avatar cab. No need to worry there! Good luck and have fun!
     
  15. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    ...snipperoo!...

    The SM-400 and the SM-400S are both stereo. Thie difference is that the SM-400S is 100w more powerful. It was the precursor to the SM-500.

    :D

    Joe.
     
  16. Joe, you are totally right. I forgot about that. :D
     
  17. babuska

    babuska

    Nov 14, 2005
    Finland
    Yes, Joe is right, our head is 400, without a S, and it is a stereo amp.
    BTW,indeed, the limiter seems to have a really hard knee. I tried it, with an interesting results. It really alters the sound. Somehow I liked the way it did it, this is a very interesting amp, I have to say.
     
  18. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Just don't ask me what I had for dinner last night!

    :D

    Joe.
     
  19. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Here, try some of this.

    [​IMG]

    It's supposed to be good for knees too.

    :D

    Joe.
     
  20. Nice legs! Are they yours? :D