Members gusfinley Posted October 13, 2005 Members Share Posted October 13, 2005 I recently bought a 12AU7 tube, to try to tame the distortion on my Marshall JCM2000 DSL401. It gave me a better gain structure, but it adversely affected the clean channel. I found out about the 12DW7 which is half a 12AX7 and half a 12AU7. Sadly, throwing one in V1 would kill my cleans and do nothing for the OD channel. After learning more about tube amps, i found that in V2 it lined up just right that it would retain my cleans and tame the OD channel. Sweet!! I threw on in there and it is sounding MUCH better - less like a chainsaw, and I can even get clean and Overdrive sounds on the OD channel rather than just DISTORTION. I also built a Gibson Goldtone GA-5 Les Paul Jr amp early in the summer. I was suprised by how loud it was and how easily it broke up. I threw my 12AU7 in there and the volume knob is MUCH more friendly now... I just completed a build of a Marshall JMP 1987 50W plexi. This sucker is loud, and it breaks up SO much more than I ever imagined!! I threw the 12AU7 into V1 and it didn't seem to do very much, really. Finally I tried throwing it in V3. That made a huge differnce. My Master Volume knob (Rich Mod) is now much more useful and I am getting great results at lower volumes. From now on, I think I will keep a stock of 12A*7 tubes on hand, as well as a 12DW7...... you guys have any success stories or ideas for swapping 12A*7 types. Link to comment Share on other sites More sharing options...
Members blackba Posted October 13, 2005 Members Share Posted October 13, 2005 I have used GE 5751's in my fender deluxe reverb reissue in place of the chinese 12AX7. The amp improved alot, the harsh treble was gone. The GE5751's were in my used mark IV when it go it and they sounded pretty good in there. I later found out that the mark IV loves GE preamp tubes, I have a couple GE 12AX7's in there currently. I would have put a 12AT7 or a 5751 in V1 of the fireball, had I kept the amp. Link to comment Share on other sites More sharing options...
Members Sordid1 Posted October 13, 2005 Members Share Posted October 13, 2005 well it's a completely different amp and circuit but I have done a lot of swapping in my XXX. I first switched to a 12at7 for the phase inverter or v4 on my amp and that helped to open up the sound and made the clean channel sparkle more. Next I tried the 12dw7 in V1,V2 and V3 but I found that in V1 it made the clean better but cut too much gain and also changed the sound of the amp, same thing in V2 and V3 so I realized I don't like these tubes. Some guys swear by them so take that for what it's worth. Next I tried a 12at7 in V1 along with V4 and I am now really happy with my sound. It added even more sparkle to the clean and opened the gain channels up even more so now I can go from a blues type breakup sound to all out metal whereas before it was stun or nothing on the drive channels. Link to comment Share on other sites More sharing options...
Members Robotechnology Posted October 13, 2005 Members Share Posted October 13, 2005 OT but, wah exactly is a Rich mod and why is it called that Link to comment Share on other sites More sharing options...
Members gusfinley Posted October 13, 2005 Author Members Share Posted October 13, 2005 Originally posted by Robotechnology OT but, wah exactly is a Rich mod and why is it called that Well, its a Post-Phase-Inverter Master volume that uses a dual ganged pot to limit the amount signal sent to the power tubes..... and Rich either invernted or popularized it. I actually had designed something very similar myslef before stumbling upon his design.... but there was more documentation on the rich mod so I went with that... Link to comment Share on other sites More sharing options...
Members ConcreteVampire Posted October 14, 2005 Members Share Posted October 14, 2005 gus, tell me more about the 2000 tube swaps.... I'm SUPER poor right now, but not above spending $12 to change my DSL2000's voicing around... Link to comment Share on other sites More sharing options...
Members gringo699c Posted October 14, 2005 Members Share Posted October 14, 2005 I have found that trying differnt 12a@7 tubes is a waste of time usually. Trying differnt brands of 12ax7 yields better results. Chris Link to comment Share on other sites More sharing options...
Members canucker1981 Posted October 14, 2005 Members Share Posted October 14, 2005 Originally posted by gringo699c I have found that trying differnt 12a@7 tubes is a waste of time usually. Trying differnt brands of 12ax7 yields better results. Chris agreed Link to comment Share on other sites More sharing options...
Members Mike_E_McGee Posted October 14, 2005 Members Share Posted October 14, 2005 So far I don't like 2 12AX7(s) in my 5E3 clone. It sounds best with a 12AY7, and a 12AX7. I'm getting Bruce's vol/tone mod though, and I'm eagerly anticipating trying 2 12AX7(s) again. I've tried a 12AT7 in both V1, and V2, but it didn't do it for me. It may have been the tube though (Mesa). So far the stock config is the best, but once I've modded, who knows... It'll be a week before I order the mod kit, and probably several weeks before I can get around to installing it. Link to comment Share on other sites More sharing options...
Members guitarded_1 Posted October 14, 2005 Members Share Posted October 14, 2005 I have always put a Mullard 12AT7 (CV4024) in the PI position on all my high gain amps. It just seems to sooth and sweeten things out quite a bit. Link to comment Share on other sites More sharing options...
Members KCA NOS Tubes Posted October 14, 2005 Members Share Posted October 14, 2005 http://kcanostubes.com/content/newsletter_details.asp?ArticleID=4 Link to comment Share on other sites More sharing options...
Members gusfinley Posted October 14, 2005 Author Members Share Posted October 14, 2005 Originally posted by ConcreteVampire gus, tell me more about the 2000 tube swaps....I'm SUPER poor right now, but not above spending $12 to change my DSL2000's voicing around... The problem with the DSL401 is that it is hard-wired for the OD2 or Red channel. The 20dB boost is really just a 20dB cut. The OD channel just has too many gain stages. Placing the 12DW7 in V2 gives the amp a workable gain on the OD1 setting, and a high-gain but less fizzy gain on the OD2 channel. You can actually hear the point on OD2 where it gets buzzy... This applies only to the DSL401 as far as I know. If you could point me to a schematic of your particular amp, I may be able to figure out what can be done. I'm not too familiar however with the rest of the JCM2000 series. by the way, if you do have a DSL401 or DSL201, i have a webpage about it Link to comment Share on other sites More sharing options...
Members Gigino Posted October 14, 2005 Members Share Posted October 14, 2005 sorry for OT but where have you found the schematcs for Gibson Goldtone GA-5 Les Paul Jr amp? Link to comment Share on other sites More sharing options...
Members gusfinley Posted October 14, 2005 Author Members Share Posted October 14, 2005 Originally posted by Gigino sorry for OT but where have you found the schematcs for Gibson Goldtone GA-5 Les Paul Jr amp? I forget, but I am hosting the one I found here Link to comment Share on other sites More sharing options...
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