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CAN I PULL A PAIR OF OUTPUT TUBES IN A CLASSIC 30 TO RUN 15 WATTS?

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  • CAN I PULL A PAIR OF OUTPUT TUBES IN A CLASSIC 30 TO RUN 15 WATTS?

    I read this suggestion in one of my tube amp books. But someone told me it could damage the amp by increasing plate voltages if the tubes are supplied in series?



    Can someone with experience tell me, please? I am playing mostly at home now, and my classic 30 and mesa nomad 45 is too loud if I want to drive the output tubes to distortion. The preamp distortion is too buzzy for my taste.



    Thanks,

    Barry
    <div class="signaturecontainer">1997 USA Fender Strat, California Series, 57/62's<br />
    1990's USA G&amp;L Legacy, OEM Seymore Duncans<br />
    Laney L5T Lionheart<br />
    Peavey Classic 30 <br />
    Mesa Boogie Nomad 45 4X10 Combo<br />
    Yamaha LD10E signed by Willie Nelson</div>

  • #2
    Well, you *should* be able to do this, but I'm not responsible if your amp takes up smoking for a while. A typical push-pull 4 tube amp like the Classic 30 has the power tubes arranged in pairs - two tubes "push" and two tubes "pull"; you want to remove one tube of each, a 'push' and a 'pull'. According the schematic, you should remove V5 and V6 together or leave them in and remove V4 and V7. It should sound very much the same until the power tubes run out of headroom. If it sounds distorted at low volumes, or does anything else strange, shut the amp off immediately.
    This space left intentionally blank.

    Comment


    • #3
      I went ahead and tried it with the amp turned around so I could see into the back of the cab. The power tube's heaters never got supplied. There was no 'glow' at all and no sound. I tried pulling the inside pair and the outside pair and got the same result, ie, no sound.

      The classic 30 doesn't have a rectifier tube or a standby switch, which is a bit strange. Usually their is one or the other. I don't know if that has anything to do with it, but there is no juice to the filiaments until all 4 PT's are in.



      Thanks for your time.



      I think this suggestion is in Dave Hunter's "The Guitar Amp Handbook", but I'm not sure.

      Seems like it said I'd need to plug the speaker into a speaker jack that is tapped for 1/2 the ohms. The peavey has a 16ohm speaker and doesn't have an 8ohm jack. I think the extension jack is probably hooked up in parallel with the 16ohm speaker, but it's a moot point now.



      Appreciate your input.

      BW
      <div class="signaturecontainer">1997 USA Fender Strat, California Series, 57/62's<br />
      1990's USA G&amp;L Legacy, OEM Seymore Duncans<br />
      Laney L5T Lionheart<br />
      Peavey Classic 30 <br />
      Mesa Boogie Nomad 45 4X10 Combo<br />
      Yamaha LD10E signed by Willie Nelson</div>

      Comment


      • #4
        It wouldn't have made much difference, anyway. The difference between 30 watts and 15 watts is only 3 dB.
        "The Web puts all of the world's knowledge at our fingertips; unfortunately it's mixed with all of the world's bull****************."
        -- Bob Parks

        "A thing is not necessarily true because a man dies for it."
        -- Oscar Wilde

        "No man dies for what he knows to be true. Men die for what they want to be true, for what some terror in their hearts tells them is not true."
        -- Oscar Wilde

        "It is a trap of history to believe that eyewitnesses remember accurately what they have lived through."
        -- Theodore White

        Comment


        • #5
          That's a good point. I have some old Rola, CTS and Eminence speakers that I pulled out of some old organs. Maybe I'll try one of them and see if they are less efficient. One of my classic 30's has an old square magnet alnico speaker in it and it sounds fantastic. The other one probably has the stock Blue Marvel in it which is pretty uninspiring. I can't tell cause the sticker on the magnet was gone before I bought it at a pawn shop. I guess I need to just buy or build a Champ and be done with it.
          <div class="signaturecontainer">1997 USA Fender Strat, California Series, 57/62's<br />
          1990's USA G&amp;L Legacy, OEM Seymore Duncans<br />
          Laney L5T Lionheart<br />
          Peavey Classic 30 <br />
          Mesa Boogie Nomad 45 4X10 Combo<br />
          Yamaha LD10E signed by Willie Nelson</div>

          Comment


          • #6
            Did you try pulling one pair or the other?
            It's 4am woman make up your mind. EITHER SPIT IT OUT OR SWALLOW IT!!!

            Comment


            • #7
              Yes. It wouldn't play at all. The heater filaments never lit up.
              <div class="signaturecontainer">1997 USA Fender Strat, California Series, 57/62's<br />
              1990's USA G&amp;L Legacy, OEM Seymore Duncans<br />
              Laney L5T Lionheart<br />
              Peavey Classic 30 <br />
              Mesa Boogie Nomad 45 4X10 Combo<br />
              Yamaha LD10E signed by Willie Nelson</div>

              Comment


              • #8
                I looked at the circuit diagram. Doest look like it would work to me.



                The two options you have are a hot plate attenuator or a low spl speaker.

                Out of the two I'd just get a low SPL speaker. Its cheaper in any case.



                I picked up a couple of these awhile back. The SPL is 89db which will likely

                drop your volume in half http://www.parts-express.com/pe/show...number=290-262

                I tried them in a cab I was building and found the tone pretty good but they just didnt put out enough volume.

                Comment


                • #9
                  The lower SPL speakers can really be a good thing at times





                  This is a Peavey Nanovalve that had the ****************tiest 8" speaker I've ever heard, but it was pretty damn loud for a 5 watt amp. I built this cab and used an old organ speaker with an obviously low SPL. Now I'm getting nice tube drive without blowing the roof of the house. For an amp like yours, I personally would go the hot plate route even though it's more expensive. That gives you the option of running the amp without it if/when you use it for gigging.
                  It's 4am woman make up your mind. EITHER SPIT IT OUT OR SWALLOW IT!!!

                  Comment


                  • #10
                    I have 2 classic 30's, so I don't mind having one that's quieter. I have a laney 5 watt , but I'm trying to get something in between. I have been offerred trades with the 15 watt Fender Blues Deluxe, but I didn't take any of them, so far. I would really like to trade for an old vintage Champ or Vibro-Champ, but I haven't found any takers yet. A princeton would be nice, but I'd have to throw in some cash or a boutique pedal. I think I'll see if any of my extra speakers are 16 ohms and give them a try. Otherwise, that SPL is super cheap. I could try dropping down to a 10 inch speaker as well. Thanks to all for the ideas.

                    BW
                    <div class="signaturecontainer">1997 USA Fender Strat, California Series, 57/62's<br />
                    1990's USA G&amp;L Legacy, OEM Seymore Duncans<br />
                    Laney L5T Lionheart<br />
                    Peavey Classic 30 <br />
                    Mesa Boogie Nomad 45 4X10 Combo<br />
                    Yamaha LD10E signed by Willie Nelson</div>

                    Comment


                    • #11
                      I have a 15W Marshall Valvestate I use for practice.

                      Its only got an 8" speaker in it so its really not big enough to rehurse without micing it.

                      I'd like to get a 30W version with either a 10 or 12" in it.

                      http://www.musiciansfriend.com/ampli...FQGFnQod30wAZQ



                      They aren't tube amps but they do use mosfets which do sound decent and a good buy for what you get.

                      I have plenty of big stuff in the studio but hauling it around just isnt worth the hastle.

                      I should really dump allot of it since I'm not playing in bands right now, but I'm not in a rush.



                      I think I'd eventually like to get a rid of my 4X12" stacks and just get a 100W Marshall or Fender Twin of some sort.

                      Then get another 30W combo for smaller stuff. If they were tube I could even go with a 50/15W pair.

                      I have three tube amps, Blackface Bassman 50W, Music Man 60, and a Sound City 60W.

                      All are as loud as my 100W Marshall Valvestate.



                      Transistor amps tend to produce lower SPL because of the way they rate amps.

                      Both transistor and tube amps use clean, undistorted sound for an RMS value.

                      A Transistor amp can often be turned up 100% and have no distortion.

                      Tube amps often have clean tone up to 50% on the volume and still have additional

                      volume above that even though it is clipped.



                      The big key to it all are the speakers. You can make a small 15W amp as loud as

                      a 50W with high SPL speakers but cab design is a big factor too. Most vintage guitar cabs

                      had little acoustic engineering involved. Open backed infinate baffle was the most common.

                      You could throw anything in them and get good midrange tone for guitar. Closed backed cabs

                      have to have the right air volume to get the speakers to sound right. The air acts like a shock

                      absorber and with too large a cab, the speakers fart out. Too small and they sound boxy.



                      I built two 4X10" cabs I really love. I have 25W Alnico Jensons in the one and a mixed bag in the other.

                      The Jensons arent the highest SPL speakers out there but the sound they produce is quite amazing for reissues.

                      I find they sound best with a good tube head and produce enough kick where you feel it in your legs standing in front of it.

                      4X10" combos are one of the best sounding stage combos too. Put a 4X10" bassman together with a Les Paul or Tele

                      and you got unbelievable tone for just about any type of music.



                      Another trick to making a smaller amp sound good is to use a thinner baffel.

                      Fender used to use 1/4" plywood suspended at only two ends. The baffel would vibrate

                      much like an acoustic guitar top does to produce additional resonance when the wood baffel vibrates.



                      I'm thinking of building a new cab with 1X10" and 2X8" speakers.

                      I want something small and light I can throw in the back trunk of my Mustang.

                      The 8's are 16 ohms and I have a bunch of 8 ohm 10's so I can get the a 4 or 8 ohm impedance

                      with three speakers. I could use a 12" and 8's too If I want. I may go with a thin front baffel too

                      which will cut down on the weight. Just a matter of laying it out and doing it at this point.

                      Comment


                      • #12
                        As I remember, the filaments are run in series so if you pull two power tubes you have

                        an open circuit...thus the remaining two wouldn't light up.
                        <div class="signaturecontainer">Oh, and by the way...the &quot;quote&quot; in the headline is fiction. Nothing in the study, or in the highly biased interpretation of the study, says that. To me, that's a sure sign the OP is trying to fit facts to an agenda, rather than base an agenda on facts.----Anderton</div>

                        Comment


                        • #13
                          I wonder if an Eminence Maverick would fit in there. Seems to be made for this situation. I haven't tried one but would be interested to hear if anyone has.
                          Guitars:
                          -Fender Wayne's World 2 Stratocaster w/Fat '50s pickups
                          -Fender Blacktop Jaguar HH
                          Amps:
                          -Fender Champion 110 w/Lil' Buddy
                          -Fender Princeton 112 Plus w/Red White and Blues
                          -Crate Palomino V8
                          Effects:
                          -Way Huge Swollen Pickle Jumbo Fuzz
                          -Pro Co You Dirty Rat Distortion
                          -MXR Carbon Copy Delay

                          Comment


                          • #14
                            http://acapella.harmony-central.com/...vey-Classic-30



                            I found this the other day, and tried it out on my Classic 30.



                            It worked, but as others said, the volume didn't seem much different. If I had to say something sounded different, it would be that there was less "presence" in the amplified sound.



                            Hope this helps.
                            <div class="signaturecontainer"><img src="http://img3.harmony-central.com/acapella/ubb/thumb.gif" border="0" alt="" title="thumbs up" class="inlineimg" />: brianeharmonjr, Bro Blue, dirteye, fragocity, Gojo03, hivedestruction, hosebeast, Kano2864212, marekk, mitre, needleTOink, PumpkinPieces, sh333, SunofNothing, this1smyne, unicornwarrior</div>

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