Preamp vs Phase Inverter vs Reverb vs Power vs Rectifier. Many people get really, really confused when they try to understand anything about tubes. What do the different tubes in an amplifier do? How do I know when it's time to change a tube on my amplifier? When should I be concerned about calibrating the bias of vacuum tubes in an. Balanced 12ax7, Who, Where And How Much? Discussion in 'The Workbench' started by Krauthammer, Jan 1. Do you recommend changing the stock Phase Inverter Tube, or should I leave well enough alone? I've read that PI Tubes can last quite a long time. For V1 in my Plexi clone, I use 7025 preamp tube. It helps tightening up the low end when.
Greetings,I really like my HRDIII with stock 12AX7 preamp tubes, but out of curiosity I wanted to try putting a 12AT7 in V1 to see how it effects the amp (since I mostly play at low or medium volume in my band).I ended up trying two separate GT12AT7 in V1 and both of them seemed to be (what I guess is) 'microphonic.' They both produced odd 'ringing' overtones, and would make them even when I knocked on the top of the amp cabinet.My question is: Does this amp (specifically the one that I own) just not like 12AT7, or should I try another tube?No big deal either way, the 12AX7s are fine. This is just a curiosity thing.Thanks. I have a Blues Deluxe Reissue.After a lot of research on preamp tubes, I use the following combination.(V1)-5751 - (V2)-5751 - (V3)-12AX7I'm sure that this combinations would work well in a Hot Rod Deluxe.Check out the following article:V3 is your 'Phase Inverter'.In V1, going from a 12AX7 to a 5751, reduces front end gain (from 100 to 60-70), and provides more clean headroom.I advise not going down to a 12AY7 (gain of 40).
As some may or may not know you can do tube swapping on the Egnater Tweaker 15 with out rebiasing since its cathode biased.Bruce Egnater has said and will say again it can take 6v6, 6L6, EL34, EL84 with Adapters, KT66, KT77, 6550 etc really any octal based tube.So with that being said. Has anyone done any tube swapping? Lets try and get a good resource with what tubes and what results.I am using a Epiphone Les Paul with Dimarzio 36th Anniversary PAF's, I dont use the amp for distortion I use pedals, so my reviews will be based off the clean channel or hot channel with limited gain.I have tried Tung Sol Reissue 6V6GT's I found these to be better then stock with out a doubt but still a bit dark sounding. Pushed the mids a little more then stock tubes. I wasnt to impressed with the Tung Sol's.I then put in a set of JJ Tubes 6v6S this really brought the amp to life, treble was increased but not in a shrill kinda way it was a nice musical high end. The bass was tightened up and not boomy and the mids blossomed well, has been in the amp since I tried them.As for preamp tubes I have tried a few and have more en route.Currently my favorite is the JJ 5751's in V1(Pre) and V2(Phase Inverter) this really brought a very creamy tone to the amp. The highs are beautiful and relaxed for lack of a better word, even with the bright engaged and treble boosted the highs never get ice picky.
The bottom end is robust but never muddy. Good creamy mids. Takes the pedals like a champ.
This is my current setup.For fun I put a set of JJ 12AU7's in V1 and V3 and this cut the power of the amp down to half or more, to get the same bedroom level volume I had the master at 50% Had a decent tone but would only use this if volume was a huge concern. Good for the bedroom guys you can get more control of your master volume. I found that if you were using pedals a 12AU7 in the V1 and the 5751 in V3 yielded awesome results and tone for pedals and those with volume concerns.I have en route a pair of JJ Hi Performance ECC803s, a Sovtek 12AX7LPS, and JJ EL34's, and currently shopping for some NOS 6P3S, and a couple pairs of KT66's. So far:Power'67 RCA 6V6GTA gray plates'74 SARATOV 6P3SI really like both. The RCAs are fantastic and I will probably go back to them again but I currently have the 6P3S set in it.PreampSovtek 12AX7WB in V1'66 Mullard 12AT7 in V1'90s National branded 5751 in V1 (Chinese)'62 Sylvania 12AX7 long plate in V1, then V3 (like this in V3, still there)'78 FENDER branded GE 12AX7 in V1 (like this, still there)The Fender branded 12AX7 was borrowed from V1 of my SF Vibro Champ.
I put another '62 long plate Sylvania in it's place and my SFVC is one happy camper. I haven't tried a 12AU7 in the amp yet but I've got a NOS Ratheon in my tube collection so I think I'll give that a try. It might be good paired with my Mullard 12AT7. They are great, which is why they are still in mine. More headroom, more bottom. Very similar to 6L6 tubes.
I ordered mine from a seller in Eastern Europe on Ebay. It took almost a month to get them but I ordered a match pair so I could use them in other amps (it's not so important in the Tweaker). They came with detailed test results which was nice. They are also very inexpensive. Just look for a seller with a lot of transactions and positive feedback and take the plunge.
I was told by others that recommended them to me that the '70s tubes have the best tone.Side note: You need to temporarily remove the top vent from the amp to get them in the sockets but once they are in you can reinstall the vent. Ok so now that I had some time to play with the JJ EL34s in the amp, I have to say I really really like them. I wasnt sure I would but man do they sound good with the 5751's in V1 and V3.Nice midrange growl, tighter bass and I think this amp is inherently dark to begin with so tightning that bass up was a nice change. Highs are not as chimey as the JJ 6V6s but they are SMOOTH!I dig them but still on the honeymoon period so I will report back in a few days.on a side note is they take a lot longer to warm up then the 6V6's as well. So hold off on that standby for a few extra seconds before playing.