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Thread: VALVULATOR GP3 Gain Modification

  1. #1
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    Exclamation VALVULATOR GP3 Gain Modification

    VALVULATOR GP3 Gain Modification July 30, 2005
    URL: www.vhtamp.com E-mail: productinfo@vhtamp.com

    NOTE - THIS IS A NEWER VERSION THAN THE ONE THAT WAS POSTED YESTERDAY!

    First off, here is the disclaimer:

    BEFORE PERFORMING THIS PROCEDURE, PLEASE BE ADVISED:

    1) THIS IS NOT A WARRANTY COVERED PROCEDURE. VHT DOES NOT WARRANTY OR ASSUME ANY LIABILITY WHATSOEVER FOR ANY DAMAGES INCURRED BY THE PERSON OR ENTITY PERFORMING THE MODIFICATION.

    2) VHT WILL NOT REPAIR OR UNDO THIS OR ANY OTHER MODIFICATIONS AND WILL NOT ISSUE A RETURN AUTHORIZATION FOR SUCH OCCURRANCES OR DAMAGE ARISING FROM POOR WORKMANSHIP, SUBSTANDARD/INCORRECT PARTS OR FAIILURE TO FOLLOW THE PROCEDURE SET FORTH BELOW.

    3) VHT STAFF WILL NOT RESPOND TO REQUESTS FOR ADDITIONAL INFORMATION REGARDING THIS MODIFICATION OR ADVICE REGARDING ANY OTHER POSSIBLE MODIFICATIONS.

    IF YOU AGREE TO THIS DISCLAIMER CLICK HERE

    IF YOU DO NOT AGREE TO THIS DISCLAIMER CLICK HERE
    Last edited by rbone100; 08-30-2005 at 08:46 PM.
    www.myspace.com/rbone100
    My bands website: www.sugarbuzzband.com
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    CLX head, UL head, CLX 2x12 Combo, Pittbull 45 Combo, VHT 4x12 with P50E's

  2. #2
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    Default

    ******IMPORTANT******

    Please....Do not contact Steve Fryette or VHT concerning this modification.
    If you have any questions about it, please post them here, and they will be responded to ASAP.

    All of the needed components can be bought from any decent electronics distributor....not Radio Shack...
    If you want to purchase these items, you can go to
    http://www.mouser.com/
    The parts will cost you about $3
    (Note) the 1000pF Ceramic Disc Capacitor is a 50 watt

    I will be doing this mod this week to one of my GP3 preamps.
    I will completely document the mod with pictures and post them here in this thread.

    Please do not do this modification if you do not know what you are doing!!!!!!!!
    You can post any questions or comments regarding this in this thread.
    Myself and other members will help you the best that we can.

    But once again....
    PLEASE DO NOT CONTACT VHT OR STEVE FRYETTE ABOUT THIS MODIFICATION!!!!!!!!

    Thanks,
    Steve
    Last edited by SteveVHT; 08-30-2005 at 06:44 PM.
    NO!!!!!
    I am not Steve Fryette....
    He just builds the most kick ass amps of all time....

  3. #3

    Default hmmm...

    (Sorry steve f for sending a question....I got excited and forgot to read the "fine print" stating that this was a double super secret mod that VHT is forbidden to discuss upon penalty of....something! )

    So I am wondering if that since changing the rhythm channel gain resistor to 200k doesn't require changing the corresponding cap, if I can also change the lead resistor to 200k (instead of 100k) and not have to also change the cap from 680pf to 1000pf...and thereby get just "a little" more gain in the lead channel, as opposed to "oversaturation"...

    My preamp was purchased used=no warranty, so I think I'll try an incremental approach:
    1) change out R1 and R11 to 28k...which I presume are the cathode resistors for V1 and V2 (no schematic, and the amp's not in front of me now) and check the sound
    2) Try the rhythm channel mod of R25 to 200k, and listen...consider trying other values in between also
    3) Try changing lead channel R34 to 200k and listen...consider values between this and 475k
    4) change R34 to the recommended 100k and then C26 to 1000 pf and listen
    5) consider other values for R1 and R11 between 28k and 54.9k
    6) (most likely outcome) re-wire it stock and be glad with what I have

    I'll post my observations here.


    off to buy "good" solder and a new tip and pieces parts,
    Drew

  4. #4
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    Well I did the mod.......
    It took about 10 minutes for the actual solder work and about 15 to take apart the amp.
    All I can say is Holy Fucknuts Batman......
    It made a huge difference and added no noise etc...
    I will post clips Wednesday night...
    I will definitely do this to my other GP3's

    I will also try to find out if this mod will work on a UL and CLX.
    This baby screams evil now....
    Steve
    NO!!!!!
    I am not Steve Fryette....
    He just builds the most kick ass amps of all time....

  5. #5
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    What is the intention behind the modification? If it would make the UL sound better (if the mod worked for that head, that is) I would definitely be interested in it.
    Gear
    Mesa Mark IVa
    Frenzel BUD 50
    Marshall 1960b 4x12
    2 Mesa Boogie Oversized Recto 4x12
    Maxon TS808
    Bodenhamer Bloody Murder
    Radial Tonebone Switchbone

  6. #6

    Default

    My take on the mod:
    Clean channel: slight change, "resonance" of that kind of midrangey tone is changed. I think I was used to the original (which sounded weird at first!). Does go into clip with gain at 3-4 o'clock w/humbuckers...a good vintage sound

    Rhythm: this channel gets the most benefit. Enough gain for anyone, and in low-gain mode even sounds great. Minimal noise added, doesn't clean up as well when turning down the guitar, but the extra gain is worth it!

    Lead: wow, what a lotta gain! For me, too much. BIG crunch with gains<12 o'clock. Corpulent lows. I think Steve thought, "you say there's not enough gain? Take this!" Again, turning off hi-gain switch still works great, esp w/deep on. I am going to try a higher value resistor in the lead channel, as well as some other caps (I'll put the 680pf back) to "split the difference" between stock and mod.

    I may try other values for r1 and r11 too to see what the difference is...I wimped out and did the whole mod instead of step by step as I had planned.
    It did only take 30 minutes to do the whole thing....not too hard.

    BTW if anyone has a hard time finding 54.9k or 28k resistors, I have a bunch....had to buy 10 of each.

    drew

  7. #7

    Default follow up

    On lots of further evaluation, I don't like the ~2.5k honkiness in the clean channel now...it is less than useful. I DO still love the rhythm channel mod...and the Lead channel is awful gain-y, near Boogie-esque.

    I will try various permutations this weekend to see what the best trade-off seems to be....short of putting a parametric EQ on the clean channel.

    drew

  8. Default

    Quote Originally Posted by drmci1
    ...and the Lead channel is awful gain-y, near Boogie-esque.
    Is it safe to asume that awful here actually means awesome?


    13_56

  9. #9

    Default aw-fulness

    Well, for me it's really a bit too much gain...I'd like a compromise between "stock" and "modded" (as usual!). For some users, I think putting the gains at 2 o'clock and turning OFF the Edge and Fat buttons (!), and putting On the Deep switch yields a awful-good ultra heavy sound. Kinda like a Recto, but you can actually hear notes.

    I'll see what it sounds like with a 2/50/2 when I get mine shipped soon...suspect I may go back closer to the stock sounds.

  10. Default

    Quote Originally Posted by drmci1
    For some users, I think putting the gains at 2 o'clock and turning OFF the Edge and Fat buttons (!), and putting On the Deep switch yields a awful-good ultra heavy sound. Kinda like a Recto, but you can actually hear notes.
    Cool...thanks for the reply!!!

    In the quote above are you refering to the modded unit with those settings? Oh how I'd LOVE to be able to get a Recto-ish tone with good definition out of my GP-3!

    BTW...does anyone know where this mod came from? Did Steve Fryette create it? The letter head on the document is clearly VHT and the way it is written seems like Steve wrote it...anyone know for sure? I would personaly feel better having it done if he created it...

    13_56

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