Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Attention current and former SWR Grand Prix owner/users:

Discussion in 'Amps and Cabs [BG]' started by bigbajo60, Jan 12, 2006.


  1. bigbajo60

    bigbajo60

    Nov 7, 2003
    Laredo, Texas
    I just scored one of these over on the Bay... and wanted to ask your personal experience with some anecdotal info I heard about SWR gear.

    It seems that some say SWR's are susceptible to damage caused by Phantom Power being present in the XLR line that's plugged into the Direct Out.

    What's been your experience?

    Oh, and thanx for sharing!
     
  2. chadds

    chadds

    Mar 18, 2000
    Hi first of all that is a piece of junk so send it to me immediately so you don't have to suffer any longer. It's true just make sure they aren't sending you any phantom power. See it it's owners manual is in the SWRENG site. Good luck. My address is 1111.....
     
  3. bigbajo60

    bigbajo60

    Nov 7, 2003
    Laredo, Texas
    :smug:

    The reason I ask is because we deal with a lot of soundmen who have no choice but to send phantom power "globally" instead of on a channel by channel basis. Is there any way around the problem? Does anyone know whether there's some kind of an in-line interruptor I can make or buy?
     
  4. chadds

    chadds

    Mar 18, 2000
    Just take a little countyman di and run it from your instrument cord or speaker out and it won't matter. My address is 11111....because you don't really want that lame excuse for a pre.
     
  5. bigbajo60

    bigbajo60

    Nov 7, 2003
    Laredo, Texas
    Ah, but it will matter! I mean, what's the point of getting your bass sound just so, if the soundman is going to make you sound like so much mud at the end?:rollno:

    I do already have a really nice DI... I guess it's experimentation time.:eyebrow:
     
  6. Personally, I've always prefered the result of using the DIRECT setting on the Grand Prix's DI over using the LINE setting. This approach is essentially the same as using a direct box. My choice of EQ seems to work with my stage rig but not as well with a house system. Never knew about the phantom power issue...
     
  7. bigbajo60

    bigbajo60

    Nov 7, 2003
    Laredo, Texas
    By saying that you weren't aware of any issue with Phantom Power, does this mean that your Grand Prix has been fed Phantom Power and you've experienced no problems... or that you've never had Phantom come anywhere near it, and therefore no problems caused?
     
  8. Let's put it this way, if phantom power has been applied to my preamp, I wasn't aware of it. Not something I'd have any reason (until now) to inquire about. No problems to date.

    What exactly IS the problem? What supposedly happens if p-power is applied?
     
  9. bigbajo60

    bigbajo60

    Nov 7, 2003
    Laredo, Texas
    The way I understand it, anecdotal information hints at serious internal damage to the unit. What, specifically wasn't mentioned... suffice it to say that the units were what most folks would call "fried".
     
  10. chucko58

    chucko58

    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    I have seen a schematic of the unit (and I used to own one). The Direct Out jack is directly connected to the outputs of a pair of op amps. If phantom power is applied, it will fry the chips. Guaranteed.

    The good news is they're not expensive chips. The bad news is that they may take out other chips when they blow.

    Many solid state preamps (the Grand Prix has 2 tube stages, the rest of the circuit is op amp chips) use capacitors in the Direct Out line to prevent frying the chips. This will block the phantom power, but it may roll off the bass and introduce phase shift. SWR presumably chose to connect directly to the jack to allow the bass signal to pass through unaltered.
     
  11. I'd be curious to know if this routing is the same for line AND direct modes? In other words are those op amps AFTER the LINE/DIRECT switch?
     
  12. bigbajo60

    bigbajo60

    Nov 7, 2003
    Laredo, Texas
    When I actually get the preamp in hand, I plan on trying to get in touch with SWR service to perhaps get some more insight into the matter. I'll be sure to post any info that comes out of that conversation...

    ...but till then, many thanx to everyone who's shared on this here thread!:D
     
  13. chucko58

    chucko58

    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    Yes, they are after the switch.
     
  14. Mmm perhaps you can get some kind of optical isolator box to go in between the DI out and the desk... maybe I am just talking out of my arse though as i have never seen such a product.
     
  15. lowmid1

    lowmid1

    Aug 16, 2002
    Baltimore, MD
    SWR corrected this so that after a certain date (I can't remember what it was) all of their products were compatible with phantom power. The fix I beleive involved caps. in DI path to block the DC. They also had a technical bulletin that was available to authorized repair centers with a schematic for doing this. Depending on when your unit was built you might not even have to worry about it.
     
  16. bigbajo60

    bigbajo60

    Nov 7, 2003
    Laredo, Texas
    I had also heard about this supposed "fix"... I'll be sure to ask SWR if they can "date" my unit via serial #.

    Hopefully it will be one of the "Phantom-Phriendly" units!:smug:
     
  17. msquared

    msquared

    Sep 19, 2004
    Kansas City
    I used to own an SWR Interstellar Overdrive with the phantom power issue. I did a lot of digging on it and it seems like when they introduced the chrome models, they fixed it. I don't know if it's the same for the Grand Prix but it'd be nice to know if that's the case.
     
  18. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    yes the phantom power is definitely an issue

    as stated, there might be a fix for it, but until you have this done i woudl not use it as a di unless you are 110% sure that no phantom power is coming its way.
     
  19. lowmid1

    lowmid1

    Aug 16, 2002
    Baltimore, MD
    After a certain date, all SWR products were built with the "fix" for phantom power. Depending on the build date, his amp might have already been "corrected" at the factory when it was built and this might be a non issue.

    I had a 1996 Sm-900 with the black face and purple and silver lettering that I had to have the fix done to and I also had a later, silver black and red Grand Prix that came "corrected" from the factory.
     
  20. +1

    Besides, SWR specifically notes that phantom power will destroy the preamp...

    Sounds like a few good reasons to not use the DI at all. I carry a Countryman Type 85 DI with me for this purpse. Usually the house wants to use theirs, which is OK also.

    My Countryman much prefers +48v than using the 9v battery. Sound is much better. Could be my unit, could be common to all Countryman DI. I cannot answer that one.