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The 6AQ5A thread!

Discussion in 'Glowing Bottle Tube Amp Forum' started by P-Nutz, Apr 26, 2016.

  1. P-Nutz

    P-Nutz Tele-Afflicted Silver Supporter

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    Picked up a '72 Fender Musicmaster that was near mint for dirt cheap, and proceeded to completely destroy what little value it had by installing a three-prong grounded plug, changing the tone knob to be more interactive, installing an Eminence Cannabis Rex speaker and putting on tilt-back legs.

    At now 25-30 lbs., it has become my number one gigging amp, and, although we mic everything, this thing is LOUD LOUD LOUD, with great natural tube breakup and compression when cranked, but nice cleans when not, and very touch sensitive.

    SS rectifier, which gets a bad rap, but 6AQ5A tubes run about $3 each and are super plentiful, so I'm expecting a good, long run ...

    Anyone else a fan?
     
  2. grolan1

    grolan1 Friend of Leo's

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    Is that you Timm? hehehehe
     
  3. uriah1

    uriah1 Telefied Gold Supporter

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    That is brilliant putting on tilt backs. Mine, was the 6v6, but, was a tad clumsy.
     
  4. mRtINY

    mRtINY Friend of Leo's

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    I've got some 6AQ5 tubes and 7 pin sockets.... I think the first project will be an AC20 with reverb.....


    -tINY
     
    Jakeboy likes this.
  5. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    I like both the 6AQ5 and 6V6 versions - and you did the critical mods. It's odd that Fender put an expensive transformer-coupled phase inverter in a (then) cheap practice amp, but lucky for guitar players! Serve ed, and with a good speaker and a few parts upgrades you can get pretty close to s 5D3 Deluxe round. open sound for very little money!
     
  6. P-Nutz

    P-Nutz Tele-Afflicted Silver Supporter

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    It is! And this is the man who sold it to me ...

    Small planet, people!
     
  7. grolan1

    grolan1 Friend of Leo's

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    Yeppers... Small!

    I'm just glad it went to someone that will put it to good use!
     
  8. printer2

    printer2 Poster Extraordinaire

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    Did a couple of 12AQ5 amps using 70V line transformers for output transformers. Want to rebuild the first as it was my first tube amp and I have had more experience with guitar amps. The second is my latest. It is like the Musicmaster amp as it has one 12AX7 and a pair of output tubes. I need to change the power supply as it is only about 240V and I want to get it up to 300V. Now rather than having an expensive signal transformer in the amp I used a Mosfet which gives a neutral PI. While the amp has enough gain with the volume and tone controls I wanted to put in a bass and treble control along with a pull switch on the bass which raises up the mids some.

    Just adding the tone stack will give some tone variation but will eat up a lot of the gain. So since I already have a Mosfet in the circuit I might as well use one as a source follower before the stack. But then I thought about the first triode stage and it really does not add much to the sound other than amplification, at least with the pickups I have. So then I thought why not use a fet to supply the first stage of gain? Then I have a triode to do with what I pleased. In the end I decided to go for a cathode follower rather than the source follower. Should be converting it right now but I wanted to see what was happening here first.

    The LND150 circuit was just a scratch pad design, not wrung out yet. Have two flavors of low voltage fet gain, going to try both and see what I like. One where the two fets are in series with each other, the bottom one here is used in pedals a fair amount.

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  9. mRtINY

    mRtINY Friend of Leo's

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    Nice little hybrid... I was thinking about 70v and 25v transformers for some amps I have in mind. It was the DC current that I was worried about.

    Apparently, there's at least one 70v tranny out there that can take the bias current for a pair of 6005's...


    -tINY
     
  10. 6942

    6942 Poster Extraordinaire

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    You can do anything that a 6V6 tube can do, with a 6AQ5 tube, at about 1/4 the cost.
    Just respect the max. plate voltage and dissipation.

    Steve
     
  11. printer2

    printer2 Poster Extraordinaire

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    I have some Sylvania tubes and they are withing a mA of each other so I am not too concerned. Could also split the cathode resistor, use a higher ohm value than normal and add a parallel resistor to bring the current where you want it. Adjustable cathode bias, and since it is split you can match them to each other.

    I was hoping to get this amp done by today, couldn't find my Fets so I had to clean up instead. Found them. Hope to get the amp tore down and up and running tomorrow.
     
  12. muscmp

    muscmp Tele-Afflicted

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    i have a 63 gibson ga5t that runs 6aq5s and i love it. put a weber speaker in and it sounds great. i don't run the tremolo as it doesn't have enough variability, so i run pedals thru it. great!!

    play music!
     
  13. Riffraff12571

    Riffraff12571 Tele-Holic

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    I had a '59 made by Univox in Japan for a while. It was a nice little amp.



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