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Running a 69-71 Blueline SVT sans Cab?

Discussion in 'Amps and Cabs [BG]' started by helenforsdale, Dec 3, 2012.

  1. helenforsdale


    Mar 25, 2007
    Howdy kids.

    Silly question, but here goes:

    I have two 69-71 Blueline SVTS that I'm just sitting on (don't ask). I haven't used either of them in years as I sold my cabs 4 years ago or so. I've got a small home studio and would love to use one of them - but is there a way to run one of these without a cab?

    Could I run a line from the "to external amp" to something like a bass pod, use that as a DI?

  2. CL400Peavey

    CL400Peavey Supporting Member

    Nov 7, 2011
    Grand Rapids Michigan
    You can not run an all tube amp with out some sort of power soak connected. Easiest would be to use a decent 115 cab, wont be crazy loud that way.
  3. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    There are no power soaks big enough to work with an SVT. You have to use a cab.
  4. Obeid Khan

    Obeid Khan Commercial User

    Jul 8, 2010
    St Louis
    Owner, Khan Audio
    Any tube amp w/ no load is a big no-no, but you probably already knew that. No power soak will be big enough like Jimmy says. You could build one like techs have on their bench, but you would need at least (2) 250w non-inductive 8 ohm resistors in parallel on a heatsink and even then keep your eyes on it....
  5. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    Never use a tube amp with no load.
    If you talk to rick at Sequis who make the motherload power soaks he can custom make you a powersoak that will deal with 300 watts into 4 ohms nominal and output a great line level speaker simulator or you can just use an 8 ohm cab lying face down on a on a thick carpet on a concrete floor to near silence it and use a standard 8 ohm motherload pro to safely soak the spare 150 watts if its well ventilated.
    I use the motherload pro dual all the time and its just the best thing you can find for obtaining great tube tone from your amp without a mic and a cab.
  6. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    With no ill effects to the amp? Can you crank it hard as well?
  7. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    Before you power up these beasts you should maybe have them checked out by a tech. Amps that have not been powered up for a while could well have dried out caps and other miscellaneous problems. A Tech will power such an amp up slowly to give the components time to refresh themselves.
  8. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    Its not a problem for the designer Rick, he just doubles up on the stuff that has already held up well to the total output of hundreds of Mesa triple rectifier heads, Imagine ultra overdriven downtune mad death metal maniacs for hours and hours without even getting hot to the touch.
    Read the reviews of the sound from the DI out.
    I can vouch for it being very very good indeed.
    I only use actual speakers as well on bass to provide slight effects from back emf and to provide other colours to the pallet but the Motherload DI sound is totally killer.
  9. helenforsdale


    Mar 25, 2007
    Thanks for the thorough responses…

    More than the home studio - I'm eventually gonna sell one, and get the other one back into a live-rig, I think.

    The main thing was that I was hoping to power them up, make sure they were working before I bothered with trying to haul them around/sell em.

    So basically, the shortest/easiest answer is - hook it up into a cab, huh?

    Second question - what about a solid state head? Specifically, the Acoustic 370.
  10. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    Get a quote from a qualified amp tech to bring them all up to voltage slowly to reform the caps on a Variac and test them.:bassist:
  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I would take the amp to a tech, and pay for an evaluation. Explain that you want to sell the amp but it hasn't been powered up in a while and that you want it checked out. Don't authorize any work till you get a written estimate.

    The condition is important but you stand to get a lot more for the amp if it has been serviced and is working. On the other hand, getting it up to spec could get really expensive. For a minimal investment, at least you'll know where you stand.
  12. The Acoustic Control Corp 370 will be fine with no cab attached (a load completes the output circuit unlike a tube amp where an output transformer completes the circuit and can run-away without a load attached).
  13. I know that some amps, such as certain Fenders, can be run without speakers by simply shorting the outputs. Not sure about SVT but can't see why it would be different.
  14. The output jack shorts with no plug inserted on Fenders to protect from operation without a cab. This is an amp saving measure not a suggested mode of operation. Just to be clear. :)

    Yes you can operate a tube amp into a short, but it can be very hard on tubes and OTs.
  15. Jim C

    Jim C Spector#496:More curves than Sophia + better sound Supporting Member

    Nov 29, 2008
    Best bass tone I ever got was with an Ampeg V4B with a 300 watt power resistor (about the size of the roll from of paper towels) and taking the line out into the console with a 60' Pbass.
    Absolutely can use a resistor like this with an SVT.
    Agree that amps that haven't been turned on in years deserve a look although I never take this advice.
    Just fired up a 60's Ampeg Jet and a Silvertone with no issues; neither had been used in 10 years; both work great and only needed pot cleaning and 1 replaced noisy preamp tube.
  16. helenforsdale


    Mar 25, 2007
    Thanks for the advice, everyone. I loathe trying to get these out of my apartment and to a tech, but you're all probably right.

    Answer this for me - I'm crazy to own two of these beasts, right? I'm about to start gigging again - but two of them, that's just nuts. Or not. And they'll age beautifully and I'll be buried with them…
  17. Double your pleasure, double your fun :D
  18. Maybe not available "off the shelf" but with dummy loads from Parts Express this is easily possible.

    My dummy load can handle 800 watts at 4 ohms. Fan-cooled as well.
  19. Steve Dallman

    Steve Dallman Supporting Member

    A Fender can operate into a short longer without damage than it will if there is no load. However, this is not a safe method of operation and the amp will fail. The protection will keep the amp alive long enough for a musician to realize he forgot to plug in the cabinet, and get it plugged in.

    A dummy load for an SVT should be able to handle two or three times the wattage of the amp. It WILL get very HOT, and fan cooling would be advised. IF it overheats and opens up the amp will go down, and not happily so. I ran my 64 Bassman head as a preamp into a 200 watt dummy load and it got incredibly hot, but the amp ran fine. I put the resistors inside a fan cooled cage made of expanded metal.

    A speaker load is not purely a resistive load, but is varying impedances over the frequency range. Will a cranked SVT operate well into a purely resistive load for long periods of time. I wouldn't guarantee it, but it is how amps are tested on a tech's bench. Marshalls don't like them as all the failures with the purely resistive Scholtz Power Soak in the 80's will demonstrate.
  20. Jim C

    Jim C Spector#496:More curves than Sophia + better sound Supporting Member

    Nov 29, 2008
    The V4B sounded great at a lowish volume with the resistor; I suppose it's all about how much you like the sound of power tubes being pushed

    As far as having 2 SVT's
    IME - They are like blue chip stocks in that no matter what new piece of gear that comes out, these will maintain their value; OTOH, they are tough to sell due to a limited market as well asshipping costs; if they are bought and paid for and you got excess cash, I'd keep the spare