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Post by Strato on Nov 22, 2006 16:17:10 GMT -7
Ive been told that 12AU7's make a great replacement for 12AX7s in tube distortion/overdrive type pedals. I was looking at KCA NOS tubes, but there are so many! Any one have any experience with these that could steer me in the right direction?
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Post by rhythmeister on Nov 22, 2006 16:52:41 GMT -7
Hmmmm. Don't know about this advice. My understanding is that a 12AU7 has less than 1/3 of the gain of a 12AX7.
I do have a Vox Brit Boost that was specially designed to utilize a 12AU7 (their "Cooltron" technology) but I don't know if I'd be swapping one of these into a 12AX7 setup.
I would defer to experts though...
Cheers, Blair
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Post by Strato on Nov 22, 2006 17:00:20 GMT -7
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Post by rhythmeister on Nov 22, 2006 17:06:51 GMT -7
OK. So I think the "toning down" and the "smoother bluesy" is what I would expect with the huge gain drop from swapping these tubes. If you are prepared (or even hoping) to lose a lot of gain from your pedal, then this might work. Good luck! Cheers, Blair
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Post by rhythmeister on Nov 22, 2006 17:36:52 GMT -7
FYI, here's a link to a thread on TGP about swapping these tubes with some replies setting out concerns, at least in an amp setting. www.thegearpage.net/board/archive/index.php/t-74835.htmlThe second post in that thread has a further link to a chart that rates the gain factors of these tubes. This chart puts the 12AX7 at 100 and the 12AU7 at 19...less than 1/5 of the gain. Cheers, Blair
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Post by Strato on Nov 22, 2006 21:14:14 GMT -7
Ha well thats pretty much what I want... The pedal soudns super harsh and fuzz-like. I will give it a shot and let you know... Anyone know which 12AU7 I should get? does it really matter?
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Post by cheycaster on Mar 24, 2007 15:41:11 GMT -7
I ahve a Real Tube pedal and I put in a NOS RCA 5963 which I believe is a 12AU7 from KCA and man, talk about round, full, and sweet. It made the RT pedal just great!
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Post by billyguitar on Mar 24, 2007 18:49:04 GMT -7
I recently bought some 12AU7s from KCA and they are great and non microphonic. I have a little Princeton no reverb amp with a lot of mods. This amp will only work with a 12AU7 as the phase inverter. It also sounds best with a 12AU7 in V1. I've had big trouble trying to find Groove Tube 12AU7s that will work in this amp and not howl. The NOS tubes from KCA work perfect in this amp. Some tube pedals don't really seem to use the tube much. I had a Tone Bone pedal for a while and switching tubes made almost no difference in it. I also had a Bad Cat 2 Tone for a few days and it didn't seem to care much what tubes were in it. I also had a Randall modular preamp combo amp and it was the same. I don't think the tubes in some of these things are used for much real tone generation.
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Post by mward on Mar 25, 2007 7:47:28 GMT -7
I accidentally bought 5 Amperex bugle boy 12au7s off ebay a while back and wasn't sure what to do with them. I don't have any tube-drive type pedals. I stuck one in my valve junior and wow talk about taking the balls out of it. At full volume it's barely going, very clean. I'll probably end up using them as PIs.
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Post by mudskipper on Mar 25, 2007 8:23:05 GMT -7
i generally much prefer 5963s than 12AU7s. RCA BP 5963s are pretty awesome sounding tubes.
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