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Switchable loads?

Discussion in 'Amps and Cabs [BG]' started by Fo' Shizzle, Oct 13, 2005.


  1. Fo' Shizzle

    Fo' Shizzle

    Aug 28, 2003
    What higher end cab companies have the option to switch from 4 to 8 ohms?

    I've got a 2 x 15 that I don't want to drag to every gig. I want to reserve it for bigger stages. But I am looking for a 2 x 12 that I can switch to 4 ohms when I use it alone. Then switch it to 8 ohms when I use it with the 15 cab (net 4 ohm load).

    Suggestions?

    Thanks,
    Fo
     
  2. Only one I know about is the multiple speaker Accugroove cabs. Lot's of threads on how these sound, etc. if you search.
     
  3. prismacolor2

    prismacolor2

    Nov 6, 2003
    Boston
    According to Bass Player magazine, the Accuswitch does nothing. The Accuswitch cabs are 4 Ohm cabs. So, ummmmm....NONE
     
  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Not possible. You would only have the option of using 8 ohm drivers either parallel or series wired, 4 or 16 ohms. 4 and 8 can't be done.
     
  5. So are you saying that Accugroove is lying in their specs, etc., and if you have two of their cabs hooked up with them switched to 8ohms they will result in a 2ohm load and not a 4ohm load????? If that's true, there will be an awful lot of customers demanding that Accugroove fix their blown up amps :confused:
     
  6. Bill,

    Lot's of discussion on previous threads on how the 'Accuswitch' or whatever it is works. While I am not an Accugroove user, I can't believe they would be lying and making up the 8 to 4 ohm switchable impedence claim.
     
  7. MODNY

    MODNY Guest

    Nov 9, 2004

    what the hell are you talking about noob

    i own 2 AG cabs

    i know they switch. **** bass player mag


    edit: this may not have been the proper response to this thread

    so...

    check out the accugrooove whappo junior man! its a sweet bass boX!




    ps: the accuswitch works.!
     
  8. prismacolor2

    prismacolor2

    Nov 6, 2003
    Boston
    Actually, I didn't say it.

    Umm, ok, are you twelve? Noob? I was playing bass for 5 years before you were even born (I graduated from High School that year)

    They certainly have a switch. The question is whether the load switches. BP says you cant hear an audible difference in the sound so how do you know for a fact that the load has actually changed (not that a sound change would necessarily mean exactly that but typically, one would expect an audible sound change when switching betweel 8 ohms and 4 ohms).

    I would like for MODNY to explain this me because he said "i know they switch." Tell me how you know.

    I have nothing against accugroove or Bass Player. I've just never understood how the accuswitch claim is possible. The BP review confirms that maybe I should be suspicious.

    I'm happy to listen, learn and understand but BP's method of bench testing the components and formulating an opinion based upon scientific fact is weighing heavier to me than Accugrooves unexplained black epoxy block.

    That's all
     
  9. NJL

    NJL

    Apr 12, 2002
    San Antonio
    interesting read...
     
  10. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    i dunno where the post is, unless somebody had the moderators delete the thread, but I did a pretty lengthy explanation of the one way that the accuswitch could possibly work. Maybe someone else can find it.
     
  11. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Not necessarily. You'd be hard pressed to tell the difference. Your amp on the other hand can tell the difference and might react quite badly if you get it wrong.

    All this arguing and it's so easy to check. Can the fellow with the accugrooves please grab a multimeter and measure the CD resistance on the cab with the switch in each position. I think you'll find in 8 ohm mode it'll read something like 6 ohms, and in 4 ohm mode it'll show something like 3 ohms. Please confirm or deny.
     
  12. Who says the switch only involves the wiring of the cabs, the switch will probably just bring a load resistor into play to get the higher impedance, altho the speakers will end up with the same amount of power each, it'll so you can use different cab combinations with your amps
     
  13. good point mohawk... that might explain why there seems to be no sound difference...?
     
  14. TaySte_2000

    TaySte_2000

    Jun 23, 2001
    Manchester, UK
    Endorsing Artist: Mojohand, Subdecay, Overwater, Matamp
    Well if everyone understood how to do it every cab would have them.

    Also generally most people don't notice much of a change when running there amps at 4 and 8 ohm the general change in tone comes from more speakers normally, I bet if you to 2 identical 4x10 and one was 4 and one was 8 ohm there wouldn't be much if any difference.

    And when any of us believe something we read in Bass Player, the world will be a sad place. :D
     
  15. Did BP actually do any measurements? Did anyone do any measurements? Someone with an Accugroove cab and a meter needs to check it and report back to us. :D

    It is possible that they're doing something that changes the reactive load seen by the amp and not the static DC load so a DC meter might not pick it up.... Maybe it does nothing at all, but I doubt it. I'm interested to know what's going on in there.

    You could use a transformer to match loads if you wanted, but I'm sure it would affect the sound at least a bit.
     
  16. Rock City

    Rock City

    Apr 8, 2001
    Boston,Ma
    http://www.talkbass.com/forum/showthread.php?t=158817&page=2
    Read through this thread. A couple of us found pretty much what Bass Player found months ago. Reading D.C. resistance on a speaker is the first way to be mis-informed. I don't always agree with Bass Players opinions, but the tech editors are not unqualified, and can certainly take accurate measurements. I they said, "the cab sounds bad", then I would have to hear it for myself. When they measure and dissect, and have the same findings I got months ago, I gotta give them the nod.
    Also, I've done EXTENSIVE searches at the Patent and Trademark office, and have found nothing to validate the claims of "Patent Pending" on the Accu-switch, or the "box-within-a-box". P.A. and Hi-Fi builders, as well as bass cab builders have used this construction method for YEARS. It's just not patentable.
    This is not a slam on Mark or Accu-Groove, as I know alot of people like his products, but I wish he would explain in depth.
     
  17. prismacolor2

    prismacolor2

    Nov 6, 2003
    Boston
    or anywhere else for that matter. Like TV, the radio, the internet, spec sheets.......I'd just like to get to the bottom of it. That's all.

    If someone else takes out that epoxied black block out of their accugroove and takes readings on what it Really does to the load, I would be interested to know how your readings differ (or not) from the BP review.
     
  18. Joelc73

    Joelc73 Supporting Member

    Nov 13, 2000
    New York
    +1 on this.

    I've been using AG cabs for a year now and I've used two of them (switched to 8 ohms) multiple times with heads that are rated at a 4 ohm min. The heads haven't even run warmer than normal let alone blown up. I certainly don't have any scientific data to back it up but they do seem to be running at 8 ohms when switched that way.

    I enjoy BP mag but I do take much of what they say with a grain of salt. I don't think they are unqualified but in this instance my gut reaction is that I think they may have mispoken. I'm sure Mark will chime in and clear this up.
     
  19. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Ladies, ladies, please stop arguing and consider the original question. Can he switch between 4 and 8 ohms with a 2x12? Barring the use of an Accu-Groove cab (which may or may not work as advertised but that's a different question entirely) the answer is no. Period.

    I didn't read the Bass Player review but offhand have to question why they didn't just take the box apart to see what was what. An electrical engineer could do so in about thirty seconds. Barring that, or someone doing actual impedance measurements of one (not DC resistance) all the speculation on how or if the thing works is a waste of time.
     
  20. prismacolor2

    prismacolor2

    Nov 6, 2003
    Boston
    EPOXY?