6AQ5A tube question

Discussion in 'Shock Brother's DIY Amps' started by RollingBender, Sep 12, 2019 at 9:19 PM.

  1. RollingBender

    RollingBender Tele-Holic Vendor Member

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    Here’s a link to the data sheet for the 6AQ5A tube. It’s a 7-pin beam pentode which is said to have similar characteristics to a 6V6 but with lower voltage.

    https://frank.pocnet.net/sheets/093/6/6AQ5A.pdf

    I have a small transformer on my bench and a clipped together power section which is reading 200VDC B+ (diode rectifier, first filter cap 33uf). The transformer has enough amp rating for what I’m thinking about doing but is this enough voltage to make those little tubes sing in P-P configuration?
     
  2. muscmp

    muscmp Tele-Afflicted

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    jimytheassassin likes this.
  3. Nickfl

    Nickfl Tele-Afflicted

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    The earlier version of the Musicmaster bass amp used them too if you want to use that for reference. About 290v on the plates, cathode biased.
     
  4. RollingBender

    RollingBender Tele-Holic Vendor Member

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    Wish I had a better understanding of how to read the graphs on some of the tube data sheets. From my kindergarten level, it looks like my 200VDC will make some pleasant sounds, just don’t know how loud and dirty.
     
  5. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    No technical info but they are a good bit less output wattage than 6v6 (or el84) AFAIK. Maybe half?
    I've read about their use and played amps that used them, seems worth a try if you have the transformers and tubes on the bench, but I have not seen much love from those who built with them with more specific goals than your have them and use them idea.
    Lower voltage ought to make them mellower and softer, suitable for a smaller than a Deluxe sort of build, eh?
     
  6. RollingBender

    RollingBender Tele-Holic Vendor Member

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    The stuff I’ve seen on the interweb built with 6aq5’s in p/p mostly claim to be 10 watts or so. A Deluxe at 10 watts would still be pretty close to a Deluxe I would think.
     
  7. rghill

    rghill Tele-Afflicted Silver Supporter

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    D-Lab on youtube has built a few cathode biased PP amps with 6AQ5 tubes. They are simplified Princeton circuits. The sound samples are wonderful.

    I have a couple of NOS 6AQ5s that I have been considering using in a build. I have a Hammond AO-44 amplifier with a nice set of transformers that I considered as a donor for the build. The power transformer puts out about 250 V to CT. The output transformer looks about the same size as a Deluxe Reverb transformer.

    Anyway, 250 VCT transformers seem to be about what these tubes like, judging by the GA-5T and a few other amps that use 6AQ5s.

    EDIT: It does seem like I have seen some builds using the Hammond 269EX at about 190V, so you could be just fine with your transformer, as long as it has enough current.
     
    Last edited: Sep 14, 2019 at 2:34 PM
  8. RollingBender

    RollingBender Tele-Holic Vendor Member

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    The transformer in question is a 269AX. It has enough current for what I have in mind. I’m drawing the chassis right now to cut on the CNC and then I will draw up a board. I’ll be starting a new thread once I start cutting things out.
     
  9. printer2

    printer2 Poster Extraordinaire

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    The transformer would be fine. 6AQ5's sound good in P-P from 200-300V.
     
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