svt vr 4 ohm into 8 ohm cabs, ampeg say don´t do it

Discussion in 'Amps [BG]' started by solitario, Nov 20, 2012.


  1. solitario

    solitario

    Joined:
    Oct 13, 2011
    Location:
    Spain
    svt vr 4 ohm into 8 ohm cabs, ampeg told me not todo it but if have seen many players vith vr and svt classic with ampeg 410 he cab that are 8 ohm.

    I asked some tech and they told me that if the cab in 8 ohm and the amp 4 ohm there should be no problem.

    are all those players with ampeg valve heads and 410 he wrong?

    thank you
  2. Bassmec

    Bassmec

    Joined:
    May 9, 2008
    Location:
    Ipswich UK
    Disclosures:
    Proprietor Springvale Studios
    If you run an SVT into an 8 ohm cabinet using the 4 ohm tap you are stressing the output tubes because there is not enough current to pull the voltages down and the output transformer insulation might start failing, causing the dreaded shorted turn and an untimely death.
    You can get away with it, but for how long? it sucks the power and it's a huge risk, don't do it.:bassist:
    PS did the engineer you asked get the tube amp concept or did he just give you a semiconductor based answer.
    If the latter he is right. Quite a lot of young engineers have no experience with tube technology.
  3. solitario

    solitario

    Joined:
    Oct 13, 2011
    Location:
    Spain
    I told him it vas a svt vr... he is supoused to know svt vr are all tube amps... I hope...
  4. arai

    arai

    Joined:
    Jul 16, 2007
    +1 to Bassmec's post
    But it it is fine to do it with someone else's gear
  5. Register to disable this ad
  6. Bassmec

    Bassmec

    Joined:
    May 9, 2008
    Location:
    Ipswich UK
    Disclosures:
    Proprietor Springvale Studios
    He gave you a semiconductor answer so he didn't seem to understand the concept of output transformer load matching in tube amps.
    Of course you could just check your cab and see if it is actually 4 X 8 ohm drivers in series parallel to arrive at 8 ohms total.
    which would add up to 2 ohms if you rewired the cab all drivers In parallel.
    You have an impedance tap on your VR for 2 Ohms so match it.:bassist:
  7. derridiandrift

    derridiandrift

    Joined:
    Apr 9, 2009
    Location:
    Hamilton ON
    Pretty sure the drivers in the 410HE are the same 32 ohm drivers from the 810E.
  8. CL400Peavey

    CL400Peavey Supporting Member

    Joined:
    Nov 7, 2011
    Media:
    11
    Albums:
    1
    Location:
    Grand Rapids Michigan
    The he's use four 32 Ohm drivers I believe. Would have to source new drivers to get the cab to a 4 or 8 ohm load.

    Personally I would look into a different cab, way more economical in the long run.
  9. Bassmec

    Bassmec

    Joined:
    May 9, 2008
    Location:
    Ipswich UK
    Disclosures:
    Proprietor Springvale Studios
    If they are, it's not going to be possible.
    do they still use 32 ohm drivers these days, I know my old CTS driver'd 8 X 10 was, seems odd because it must cost them in Ampeg only application terms. quantity ordered cost considerations.
    That's why I said if they are 8 ohms.:bassist:
  10. JimmyM

    JimmyM Supporting Member

    Joined:
    Apr 11, 2005
    Location:
    Apopka, FL
    Disclosures:
    Endorsing: Ampeg Amps, EMG Pickups
    If you keep the volume low, you can usually use an 8 ohm cab with an SVT without incident. But it's certainly not recommended.
  11. walterw

    walterw Supportive Fender Gold Supporting Member

    Joined:
    Feb 20, 2009
    right;

    you can run your 5-speed car on the highway in 3rd gear, but is it a good idea?
  12. wilfredes

    wilfredes

    Joined:
    Oct 11, 2012
    Would have to source new drivers to get the cab to a 4 or 8 ohm load.
    [​IMG]
    [​IMG]
  13. beans-on-toast

    beans-on-toast

    Joined:
    Aug 7, 2008
    Ampeg gave you their "official" answer. The amp should be matched to the cab for optimal performance.

    People run with the bulls. That doesn't make it safe.
  14. ScottTunes

    ScottTunes

    Joined:
    Feb 7, 2011
    In the ignorance is bliss column, I used my V-9 SVT (1976 Magnavox era) through 8 ohm cabs many times, although for relatively low volume sits... Back then I was told you could go "up or down" basically one level - meaning using an 8 ohm amp into 4 ohms, and/or a 4 ohm amp into 8 ohms (with tube heads anyway)... But matching is the best option.

Share This Page