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Peavey Classic 30/Delta Blues Power Reduction Mod

Discussion in 'Amp Central Station' started by Agave_Blue, Oct 6, 2010.

  1. dhuber

    dhuber Tele-Meister

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    If you just want a lower volume put a volume box in the effects loop. This allows you to turn up the pre amp tubes and then drop the volume before the power section. The classic 30 has the volume in the front section of the pre amp. So when you turn down the volume the hiss remains high because the rest of the pre amp is at full volume. I get real nice bedroom levels with the volume box. I don't get real crazy with the pre amp either I think I have the normal volume at 5 on the clean channel and the pre at 3 post at 10 on the gain channel. I use the volume box to adjust the actual volume coming out of the amp and I get real nice tone at practice levels.

    However if you want to drive the power tubes harder this mod in the post should do it. What bums me out is I hate to cut the pins off of a perfectly good tube. Especially when I've thrown out used EL 84's in the past that had perfectly good heaters.

    I'm definitely going to do the 15 watt mod, but I think I'll wait until I have some spent up power tubes.
     
  2. DaBender

    DaBender Tele-Afflicted

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    Do you really get more reverb, or do you just get to turn the knob further?
     
  3. bluescube

    bluescube Friend of Leo's

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    What about speaker impedance?
     
  4. dhuber

    dhuber Tele-Meister

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    I found 4 old Sovtek tubes today. I only cut off pins 2, 3, and 7. I left pin 9 on and I know that's one side of the screen but with the other end of the screen off it should not matter. Having pins 1, 4, 5, 6, and 9 in tact it is less likely to put the tube in wrong. I really can't tell that much of a difference in tone. There is definitely some headroom missing. I have one Peavey 30 at home for practice and I have another at church I use as a monitor. Neither one gets cranked up. I'm still going to use my external volume control in the effects loop.

    As far as impedance amplifier to speaker match up I can't answer the question. I was already running Reverend All Tone speakers which are 8 ohms instead of 16. In my mind taking one push pull amplifier section out should increase the impedance of the amplifier stage by 2 times being both stages were in parallel. It's like having two horses side by side pulling a plow. If you remove one horse the load has not changed so the one horse connected to the plow is going to have to work twice as hard. So if you want to match impedance I'd think you would want to go from 16 to 32 ohms with your speaker which would cut the current to the speaker in 1/2.
    That's why I don't think I'm hearing that much difference in output. Because the one stage left is working twice as hard. In my case it's probably 4 times as hard being I'm running an 8 ohm speaker.

    It sounds fine to me. I'll be changing my amp at church tomorrow. I guess I'll see how the tubes hold up. 15 watts of power is more than enough for me.

    I have a Peavey Classic 100 boxed up that has not been used for 5 years and that had 8 EL84 in the output. I always ran 4 EL 84's with that amp with no trouble.
     
    Last edited: Apr 12, 2014
  5. OaklandA

    OaklandA Friend of Leo's Platinum Supporter

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    +1

    When I had a Delta Blues a few years back, I put 5751's in V1, V2, and V3. Lowered the perceived output as well as smoothed out the boost in a nice way. Would be a cheap, easily reversible experiment as well.
     
  6. peavey30

    peavey30 Tele-Meister

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    I have done the mod about half a year ago. I'm very pleased with it. Especially the drive channel is much better on bedroom levels. Yesterday I have put the 4 'original' tubes back in the amp. My neighbor can definitely hear the difference. Within half an hour she rang at my door.
     
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