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12AT7 tube in a Hotrod Deluxe

Discussion in 'Glowing Bottle Tube Amp Forum' started by motwang, Nov 23, 2015.

  1. pawleep

    pawleep TDPRI Member

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    seems like the general consensuses to not put a 12AT in V1 or V2, but maybe v-3? what about a potential position to try a 12 AU7 or 12AV7 ? (that I have laying around) is a 1995/6 2-12 hotrod deville

    I am considering changing the volume to an audio pot too as recommended in a prior post.. but not sure which volume pot that ya'llz are referring to
     
  2. pawleep

    pawleep TDPRI Member

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    just wondering what PI and GB are abbreviations for?
    thanx, p
     
  3. homesick345

    homesick345 Poster Extraordinaire

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    GB would be George Benson?

    PI is phase inverter - ususally a 12AT7 on Fender bf/sf amps
     
  4. pawleep

    pawleep TDPRI Member

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    thanx homesick... do You think a 12au or 12av7(have one) would be ok to try in the PI of a 1996 hotrod deville is V3 i suppose
    or would they be better to try in V1 or V2?
    still trying to figure out if the letter designations are in some kind of order , relative to their gain levels

    addendum: also wondering if you know if there are any rellevant downsides to trying a 12AT in the HR Devlle PI as you said was probably good to put in the champ PI?
     
    Last edited: May 15, 2016
  5. homesick345

    homesick345 Poster Extraordinaire

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    I don't think there is any downside to put an AT7 in V3. It will calm the amp down a bit. It will sound a bit more "hollow"

    As for other positions, I have tried almsot every possible combination (mainly to make the drive channel usable) - I'm afraid nothing works

    My advise is to concentrate on the HRD forte, which can be a very good clean sound/channel. And put a good drive pedal in front - when needed.

    EDIT: Georges Benson sure wanted a totally clean sound - hence the AT7 in V1 (he's a Jazz player). Jazz players will sacrifice eagerly "richness" & borderline breakup for totally clean & defined sound (something a Blues player might not like) - so I think Fender/GB went AT7 to cater for Jazz.
     
    Last edited: May 15, 2016
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  6. pawleep

    pawleep TDPRI Member

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    when You say "more hollow" no sure what You mean, is it in a bad way?

     
  7. homesick345

    homesick345 Poster Extraordinaire

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    I mean less compressed, maybe a tad less middy. No, not in a bad way at all. A nice change
     
  8. johnnyha

    johnnyha Tele-Afflicted

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    Y'all got me ordering a NOS Mullard 12AT7… 1979 military issue looks pristine.
     
  9. doof

    doof Tele-Holic

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    i tried the 12AT7 trick in my hotrod deluxe because i had read plenty of success stories on the internet, but sadly it made no noticeable difference for me.
     
  10. ballynally2

    ballynally2 Tele-Holic

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    a GOOD (RCA) 5751 in V1 or V2. 12 AT for PI
     
  11. Andy B

    Andy B Friend of Leo's Silver Supporter

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    We had a George Benson Model in the shop & it came with a 12AT7 in V1.
     
  12. pawleep

    pawleep TDPRI Member

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    so, i guess you could get the mids back up with the mid eq?
    some guys said a 12au or 12ay or a Mullard 7024 in v1 or v2 was good. or maybe a pro amp builder could configure a new gain channel section? or like you said a good drive (boost and or overdrive pedal) in the pedal array?
     
  13. homesick345

    homesick345 Poster Extraordinaire

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    Well, not saying that the AT7 you could necessarily like, BUT you should notice its presence. THis is not "unnoticeable" .
     
  14. homesick345

    homesick345 Poster Extraordinaire

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    The amp being what it is, (PCB) I don't think modding would be easy. (to be honest I don't think it's worth it: you would end paying good cash for a hypothetical result)

    Your best bet is to concentrate on the cleans (which can be excellent) - & put a drive in front. Many excellent overdrives from Wamper (as an example) could work great depending what you want

    Again; my advice is to use the HRD like a DRRI or something: consider it a classic 1-channel amp. Forget the overdrive. It will never work (at least for me, it never did.
     
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  15. codamedia

    codamedia Poster Extraordinaire

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    I'm not so sure this is just a "jazz" thing... what it does do is help provide a very controllable clean platform. When I owned a Blues Deluxe (very similar to an HRD) I used to use a 12AT7 in V1 and I really liked it. The 0-3 volume issue was gone and I had a nice sweep throughout the entire range. I didn't notice a loss in tone at all (slight difference, but no loss)... and there was never a shortage of power so although the amp would have lost some power with the tube swap, I never hit that range anyway. My breakup/dirt always comes from pedals.

    As for what tube I put in there... I have no idea :D. I raided two old 60's console radios a few years back so that is where it would have come from... but I can't tell you what brand. All I know is that it was a 12AT7.
     
  16. homesick345

    homesick345 Poster Extraordinaire

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    I have no problem in this - noting that we are saying essentially the same thing: Fender went further with the GB to make it a clean platform, as you say

    Experimenting with tubes is sure THE fun thing to do with tube amps. Each will hear generally different things - but I think we all agree the AT7 will tame the amp & clean it up.
     
  17. Jack S

    Jack S Friend of Leo's

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    I am not currently using my Blues Deluxe, which of course is same family as the Hot Rod, but I put a 12AT7 in P1 replacing the 12AX7 and the difference was day and night. Of course, I never used the drive channel at all and mostly want to play clean, but it gave me control over the volume knob making it unnecessary to swap it out.

    I find the drive channel on those amps sound terrible to my ears anyway, so keeping it clean and using a pedal if I want some dirt is the way to go.
     
  18. Andy B

    Andy B Friend of Leo's Silver Supporter

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    Try a 12AT7 in V2 it tames the drive channel making it much more user friendly. You can't hurt anything swapping these tubes.
     
  19. ballynally2

    ballynally2 Tele-Holic

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    I suggest you do some further research. There's lots of practical info out there. Make sure you get the right details. Not all valves are the same, even the ones of the same type. For instance, some ATs might do as preamp valves but most do not, while you can use most ATs in PI. The preferred 12AX7 replacement seems to be the 5751 but some like the AY. Plus the specs of particular valves could be all over the place. My own standard would be how clean/open/ does the valve stay when cranked ie, i love clean power and i let the amp do the work. But some prefer the earlier grit of the 12ax7. can't argue with opinions. Some posts here appear rather uninformed..

    I have 2 RCA 5751 blackplates that are in 2 amps. I can feel the amp's power when cranked and their producing a wonderful overdrive. GEs are nice but more gritty.
    And so on..the right amp for the right place..etc.
     
    Last edited: May 16, 2016
  20. Rick330man

    Rick330man Tele-Afflicted

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    I've owned 2 HRDs. I've experimented with tubes & speakers extensively.

    A buddy of mine bought one off of me a few months ago. I swapped out all tubes and gave him a complete new set before selling him the amp. He wants to play rockabilly and a lot of 60s stuff while still being able to tap the "DRIVE" and "MORE DRIVE" options without needing to resort to a pedal.

    In V1, I stuck an EH12AY7. My preference is a 5751 in here. With either a 12AY7 or a 5751, the goal is to tame the obnoxious up front gain on these while retaining the amp's musical qualities. Either a 12AY7 or a 5751 does the trick.

    V2 can sound ratty. I stuck a JJ ECC83S in there. Most of you know that those tubes can sound a little muddy in some circuits. To my ears it is perfect for the HRD in this application. And since you're cutting back a lot of gain in V1, you don't want to overdo it and cut too much more in V2.

    V3: here is where the 12AT7 goes. I used a JAN Philips. They are great for this kind of duty.
    The 12AT7 in V3 drops your presence a little, but that helps tame the boomy bass and the occasionally shrill highs HRDs can give you.
     
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