The Pro Deluxe ( Terry Shaffer Build )

Discussion in 'Building the Classics' started by johnfv, Mar 31, 2018.

  1. johnfv

    johnfv Well-Known Member

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    I know many members here are familiar with Terry (Guitar-Rocker) and his work. I'm finally getting around to posting this great amp Terry did for me. I asked him to rebuild what had been a Marshall style 18W amp into a Fender style. I have many "crunch" amps and instead wanted something I can use for true cleans and as a pedal platform. After discussing options this is what we settled on: "The Pro Deluxe" is based on both the Fender Deluxe and Pro amps (the output section is like a Deluxe 2 x 6V6). Terry really did a killer job on this!

    It has some cool custom features including:
    Rear B+ switch: allows choosing the higher voltage Pro setting, or the lower voltage Deluxe setting for the preamp section. I've mostly used the Pro setting for the added headroom but the lower setting is great for more grit when desired.

    NFB switch: controls the level of feedback (in this case more like Presence). Center position, all NFB is defeated. Up the NFB is set to standard Fender fixed value. Down the NFB is half the Fender set value. I have found I like the lower position (1/2 value) best.

    Middle knob: I wanted a mid control similar to a Twin or Showman. Terry set it up so all the way off is the standard Fender fixed value of 6.8K (in other words like a stock Deluxe or Pro), as you twist it higher it goes to a maximum Mid value of 16.8K.

    I'm showing it with what has been one of my most used small rigs, a Ceriatone Prinztone head (Princeton clone) and an angled front 1x12 cabinet (loaded with a V30). I use this quite a bit for gigs at smaller venues with pedals or my Axe FX in front. I have a couple of gigs coming up soon, this time I'll be using the Pro Deluxe. It has more volume/headroom and with the mid and added controls has a lot of flexibility. I still love the Princeton but am very happy to also have The Pro Deluxe!


    ProDeluxe1.jpg ProDeluxe2.jpg ProDeluxeStack.jpg
     
    Last edited: Mar 31, 2018
  2. Ghostman

    Ghostman Well-Known Member

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    [​IMG]
     
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  3. jensvonbustenskjol

    jensvonbustenskjol Active Member

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    That's just plain awesome!!!
     
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  4. CoyotesGator

    CoyotesGator Well-Known Member

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    I’ve heard many great things about this amp!

    I would love to hear some gig clips if you get a chance.
     
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  5. johnfv

    johnfv Well-Known Member

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    Yes, I need to work on a clip of some sort to share how great it sounds. Terry has built some great amps but IMO he really killed it on this one, it's one of the best sounding "Fenderish" amps I've ever heard. I forgot to mention that it has both low and hi inputs, I mostly use the low since I'm going for clean headroom. But with the higher gain input, dialing in the mids, tweaking the B+ and NFB - it can venture more into "British" territory. I told Terry I hope he took good notes on the build because it is definitely a keeper. In fact I think he has some internal pictures, perhaps he will share.
     
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  6. DirtySteve

    DirtySteve Well-Known Member VIP Member

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    Awesome amp I'm sure, glad you posted it. I love my GR amps!
     
  7. ampmadscientist

    ampmadscientist Well-Known Member

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    On the wrong side of the tracks.
    We wanna see the insides.
    Quit teasing me.
    Purple tolex does improve tone vastly, scientists have studied this phenomenon.
     
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  8. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    When John asked about reworking his amp, we talked about where he wanted to go and what we had to work with. The existing iron had capabilities to reach the plate values of the AB763 circuits, but not enough mA to support 6L6GC's. In order to give the amp a lot of headroom and clarity, we decided to use the JJ 6V6S tubes rated for higher plate voltages than the run of the mill 6V6's as our plate voltage ended up at @ 421V. (6Volts higher than the Deluxe which runs 6V6's and 19Volts lower than the Pro that runs 6L6GC's)

    The amp has a set voltage for the power section, fixed bias JJ 6V6S tubes P-P, and the preamp has dual B+ rails. One rail has as close to the AB763 preamp voltages as we could go (about 8 volts lower than the Pro), the other rail is spot on AB763 Deluxe voltages. The amp turned out nicely and gives John those little tone tweaks that he was looking for. Thank you John for the nice write up, glad the amp fits your needs.
     
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  9. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    [​IMG]

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    Last edited: Apr 2, 2018
  10. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    Not to take anything away from John's thread, but I did like the Pro Deluxe enough to build one for me too, however mine is a 6L6GC version, mounted in a combo. Please note in the photo that I was short one valve retainer that has been since added.


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  11. johnfv

    johnfv Well-Known Member

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    NICE!
     
  12. el_bastardo

    el_bastardo Well-Known Member

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    Goddamn that wiring is sick!

    Question: As I continually try to wrap my head around this stuff, I'm looking at the heater wiring. I see the heater wires have a turret strip with some resistors between the filaments and the PT heater tap. Is that strip/resistors what's referred to as a "elevated" heater circuit?
     
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  13. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    It's a 100R / 100R connection point for filament supplies whose coils aren't center tapped, or in short an artificial center tap point. I used 100R's. Two excerpts below are from the Valve Wizard:

    Artificial Centre Tap
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    If the transformer doesn't have a centre tap then you can create an artificial one using a pair of resistors. The resistors should have a fairly low resistance to help shunt leakage currents from the transformer primary. Values of 100R (1/2W) or 220R (1/4W) are typical. They will of course consume a little extra current from the transformer (32mA when using 100R resistors at 6.3V) so bare this in mind.



    Heater Elevation
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    Elevation means referencing the heater supply to a DC voltage other than ground or zero volts. The heaters still operate at 6.3V or whatever, but this floats on top of the elevation voltage. Some valve stages such as cathode followers require the heater supply to be elevated to avoid exceeding the valve's Vhk(max) rating. But even when not explicitly needed, elevation can reduce hum in AC-heated circuits by reducing or saturating the leakage current between heater and cathode.*

    The DC voltage is applied to a transformer centre tap, artificial centre tap, humdinger, or whatever reference connection the heater supply would normally have.

    The elevation voltage can be taken from a potential divider across the HT (it doesn't matter where you position the divider), and an elevation voltage around 30 to 60V is typical. The divider should have a fairly high resistance so as not to waste current, although the lower arm (R2) should not be excessively large or Rhk(max) may be grossly exceeded, so it is advisable not to make it greater than 100k. The elevation voltage should be decoupled/smoothed with an arbitrarily large capacitor (C1), say 10uF or more.

    Another convenient source of elevation voltage is the cathode of a cathode-biased power valve. No current flows ‘into’ the heater supply from here, so the power valve bias is not affected.
     
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  14. el_bastardo

    el_bastardo Well-Known Member

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    Okay thank you. So what you did was create and "artificial" center tap, but it's not elevated. I think I got it.
     
  15. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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  16. el_bastardo

    el_bastardo Well-Known Member

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    Could you elevate your artificial center tap? Doesn't elevated heaters reduce noise?
     
  17. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    Yes, one could elevate the center tap. It's much easier to elevate a center tap in a cathode bias amp vs a fixed bias where you would need to find a HT source (because the source in a cathode bias is already there, power tube cathode bias). My limited test experience in trying elevating was not rewarding enough for me to bother with it, but others may have had better success than I have had.

    What worked the best for me is proper wire routing.
     
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  18. el_bastardo

    el_bastardo Well-Known Member

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    Gotcha, I understand. Thanks.
     
  19. danfrank

    danfrank Well-Known Member

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    I agree with this; not worth the effort. In fact, in some builds the noise floor was greater with elevated heaters! LOL!
    I like how you run the filament wiring through the center of the preamp tube sockets between pins 1 & 9; it works well for low noise.
     
  20. DirtySteve

    DirtySteve Well-Known Member VIP Member

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    Best derail EVER!! :applause:
     
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