Gene's 5F4/5E7/5E5-A Build?

Discussion in 'Shock Brother's DIY Amps' started by The Ballzz, Dec 15, 2019.

  1. The Ballzz

    The Ballzz Tele-Afflicted

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    @Wally has given me the inspiration (yeah, it's his fault :twisted:) to do my next build as a 5F4/5E7/5E5-A, but utilizing the phase invert and cathode bias 6V6 power section of the 5E3 Deluxe. Upon fairly close inspection of the schematics, the three mentioned amps are identical except for resistor values in the local feedback loops around V2, the presence loops and the 5E5-A PRO running at lower voltages, across the board than the other two. I'm thinking it may be a good idea to put the local feedback resistor on a 3-way switch to choose between none, 5E7 & 5F4 values.

    I am still however torn between the above mentioned design and a 5E8-A (and a few other models) pre, with each input actually sporting two triodes. Though I've never had the chance to try such a thing, I'm intrigued by the concept of finding a way to utilize both triodes, in parallel on each channel and then jumper/Y-jack them to run both channels. I realize it may be less stellar in practice than it seems on paper? I'd love to hear from anyone who's been down this rabbit hole and/or tried it? Note that the designs with two triodes per channel do not have the standard 68K grid stoppers!

    Still Schemin' & Plannin'
    Gene
     
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  2. D'tar

    D'tar Friend of Leo's

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    Subscribed hoping this ends with sound clips!!!
     
  3. FenderLover

    FenderLover Poster Extraordinaire

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    Are you proposing to potentially run four input triodes in parallel, you crazy mad man? Never tried it, but I'd like to hear it.

    Another route may be to go with the 5F4/5E7, but split the cathode circuit on the input stage to voice them separately and A-B-Y between them.
     
  4. AJBaker

    AJBaker Friend of Leo's

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    So you would end up with 12w?
    Sounds cool, but I would be curious to see the 6L6 version too. I've read that the output transformer was the big thing that made the super unique: although the 2x 6L6 power section could theoretically get up to 40w like a bassman, the speaker technology of the day meant that two 10" speakers could never handle that. So the output transformer was undersized to bring the output down to about 25w (don't quote me on the exact number), and the type of winding on the transformer also changed the sound quite a lot compared to a bassman.
     
  5. Wally

    Wally Telefied Ad Free Member

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    I have owned a 5E8A as well as the 5E7’s and 5E5A. If you build the 5E8A with a switch on one of the rectifiers to drop it out, you in essence have the same amp as the Pro/Super/Bandmaster....with the big differences among the 4 being those NFB loops...and OT’s. Switching those feedback resistances would be of 8nterest8nginterestinginterest. Of the three models I have owned, the 5E7 is my favorite. Ommv.
    and....the 4x Jensen P10R’s would not stand up in a 5F6A if played the way a rock player would use the amp. Fender went to P12Q’s in the last year of production...1960. 2 x vintage P10R’s had a capability rating of 10 watts each....so they were under-rated for the Super. They were barely sufficient for the Bandmaster....if that amp were pushed hard, the speakers would be hard pressed to maintain viability. The 15” P15N was rated at perhaps 20 watts! The Jensen Alnicos of that time we’re simply not enough speaker except if the amps were used the way Leo envisioned them, I suppose....played cleanly.
    Luckily, modern materials allow the Emi ALK or the Weber 10A’s to be able to handle these amps in a better manner.
     
  6. The Ballzz

    The Ballzz Tele-Afflicted

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    As blasphemous as this may seem, I'm a Celestion Greenback/Creamback kinda guy. While they may not give that classic Jensen sound, I like what they do! While possibly lacking a tiny bit of the "sparkle" they've got an ability to "grunt" like nobody's business! :twisted:

    And @Wally , I see what you mean about the similarities & differences. I will definitely play around with component values in those loops. On the other side of that, I'm not sure putting different values on a switch is needed, as once I find "MY" thing, it will stay that way forever! I am still intrigued and curious about the extra triodes in the first gain stage(s) of that 5E8-A, along with the various ways/possibilities of using them in parallel and torn as to whether it is worth the effort for the extra tube or not? Without actually trying it, I'm suspecting that it may get a bit too bottom heavy/tubby, but won't know unless I try or someone with experience shares. Any light you could shed on that part of the equation would be well appreciated?

    Thanks Folks,
    Gene
     
  7. Wally

    Wally Telefied Ad Free Member

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    Well, then you wouldn’t have a tweed Fender amp if you did that parallel triodes thing, now would you? (;^)
    I would rather suggest what many ‘modern’ amps have done with the basic preamp of the big late ‘50’s tweed. Build a single channel amp, separate those two triodes that exist as the preamp gain stages, and drop one in after the first gain stage when more gain is wanted.
    This is the format of the Marshall JMP Md. 2203 MV amp from the 1970’s.....great amps.

    if you want to you one more tube, you could build a Soldano SLO or a Fender Pro Sonic preamp....the Soldano can get to a 5 triode gain stage prior to the tone stack....the Pro Sonic only gets to 4. The Pro Sonic creates a lot of gain.....or you can take it back to the 5F6A 2 gain stages prior to the tone stack format.
     
  8. The Ballzz

    The Ballzz Tele-Afflicted

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    Yes @Wally , I'm well aware of those different scenarios and have already done a few of them. I am though still trying to understand the possible functionalities of the 5E8-A (and a couple other models) 4-hole/4-triode preamp which is very different than the normal 4-hole/1MEG/68K/68K input stages. The concept of parallel triodes seems interesting, but may simply suck dead eggs? I do understand many of the varied things that can be done with multiple triodes. On the other hand, perusing/comparing the widely and wildly diverse versions of these old Fenders has me hoping for answers to at least some of my questions without needing to build whole amps just to answer those questions for myself. Does that make any kind of sense?

    Thanks For All Your Help! :D
    Gene
     
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  9. Wally

    Wally Telefied Ad Free Member

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    Well, alright then....turn it every which way but loose, and then let us know what you find. Learning is for me.
    It does appear to be an expensive way to utilize those four triodes....as a Leo did it..right? I have never wondered about it before. I owned the 5E8A back in the ‘90’s...when I knew even less than I do now about these amps. In fact, I did not do amp tech work 25 years ago. I had an excellent tech who worked on every amp I bought. I plugged in and enjoyed....
     
  10. printer2

    printer2 Poster Extraordinaire

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    [​IMG]

    Absolutely not suggesting anything.
     
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  11. The Ballzz

    The Ballzz Tele-Afflicted

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    Closer to a 5E5-"A" layout and that's a very interestingly unusual tube complement. Never heard of a 12V6 before. It would be interesting to see the power supply layout and even the voltages.
    Thanx 4 Sharon,
    Gene
     
  12. printer2

    printer2 Poster Extraordinaire

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    12V6 is a 12V 6V6, made for cars when they went 12V. I had a different schematic I was trying to find but it was with different software than I have now and the picture of it used to be hosted on Photoshop, we won't talk about them now. Matt, a poster a while back asked for something and I modified a schematic I had to show what it might look like. It was never an amp, just something to take ideas off off. I have a lot of ideas but not enough time to do them all.

    I probably wouldn't do the above circuit anyway. I would rather have a Bassman stack in place of the above tone control. the schematic I was looking for switched in and out the above tone controls and the Bassman. Just a double pole two position switch at the input and the output of the above tone controls with the Fender stack swapped in. You were asking about doubling up the triodes so I thought if you wanted variety maybe a tweed volume-tone control channel might be of interest. What the heck, I have the software open, I'll do a quick modification.

    [​IMG]

    With 6V6's this time.
     
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