Crate V18 Bass And Reverb FIX ~ $1

Discussion in 'Amps and Cabs' started by Mark dB, Oct 5, 2008.


  1. Mark dB

    Mark dB Member

    Messages:
    73
    Joined:
    Aug 8, 2007
    Location:
    north by northwest
    For those of you who picked up a V18 and found them to be too bassy and the reverb too sproingy, here's a low cost fix for both issues.

    DISCLAIMER: ONLY QUALIFIED PEOPLE SHOULD MODIFY A GUITAR AMP. HAVE AN AMP TECHNICIAN MAKE ANY MODIFICATIONS. HIGH VOLTAGES INSIDE A TUBE AMPLIFIER CAN HURT OR KILL YOU.

    The fix requires two components...
    1.) a 0.68 uF (microFarad) / 50 volt capacitor
    2.) a 680 ohm / .25 watt resistor

    The fix involves easy access to the amp's internals. First unplug the amplifier! Then remove the eight screws that hold on the back cover of the amp. No other disassembly is necessary. Check for residual high voltages!

    To fix the overwhelming bass problem, replace capacitor C13 with a 0.68 uF capacitor. C13 is a 2.2 uF / 50 Volt electrolytic polarized cap. It is a small blue vertical tubular component that stands up off the circuit board on two legs and has some hot melt glue helping to hold it in place. Carefully remove the glue away from the capacitor to expose the leads (legs). Note which leg is negative by the markings on the capacitor and the silkscreen on the circuit board. Clip off the tubular part of the capacitor, leaving the two legs sticking up out of the circuit board. Solder the 0.68 uF capacitor to the leftover legs, observing the correct polarity. Keep the new leg length short.

    To fix the sproingy reverb, add a 680 ohm resistor in parallel with R36. Solder one leg of the 680 ohm resistor to one leg of the 4.7 Kohm R36 resistor, and then solder the other leg of each resistor together. That is two solder joints total.

    Replace the rear cover. Plug in the V18. Rock out.

    If you are a qualified amp tech, the mod will take you 15 minutes and $1 in parts. If you are not an amp tech, take it to someone who is, and pay them $25 to make the mods.
     
  2. jimwratt

    jimwratt Member

    Messages:
    21
    Joined:
    Dec 28, 2007
    do you have some a/b clips available?
     
  3. Mark dB

    Mark dB Member

    Messages:
    73
    Joined:
    Aug 8, 2007
    Location:
    north by northwest
    Sorry jimwratt, but no before and after clips from me.

    The amp sounds the same, but with the cap change, you turn the bass knob down to zero and it actually reduces the bass, while '5' on the dial is about average bass.

    The reverb resistor mod just reduces the amount of drive to the reverb tank. The "REVERB" knob, which controls the amount of 'recovery' from the other end of the
    reverb springs works exactly the same as before, but now sounds smoother and more refined.
     
  4. RussB

    RussB low rent hobbyist Silver Supporting Member

    Messages:
    10,735
    Joined:
    Jul 3, 2004
    Location:
    connecticustan
    Very interesting, Mark db
     
    Last edited: Oct 24, 2008
  5. pja51

    pja51 Member

    Messages:
    1
    Joined:
    Oct 17, 2008
    I checked it out, this guy is a genious, been servicing and modifying tube amps for 30 years. A couple of component changes, and my Crate V18-112 sounds just like my 1974 Marshall stack.

    It's worth every penny. Gofer it!

    Butch
     
  6. RussB

    RussB low rent hobbyist Silver Supporting Member

    Messages:
    10,735
    Joined:
    Jul 3, 2004
    Location:
    connecticustan

    A shill post if I've ever seen one.:boxer
     
  7. Wesman61

    Wesman61 Member

    Messages:
    3,791
    Joined:
    Nov 9, 2004
    :rotflmao
     
  8. ruppert240

    ruppert240 Member

    Messages:
    207
    Joined:
    Feb 14, 2008
    not.....fooling......anyone.....
     
  9. gag halfrunt

    gag halfrunt A fellow of infinite jest

    Messages:
    1,868
    Joined:
    Aug 30, 2005
    Location:
    Marquette, Michigan
    :)

    Indeed.
     
    Last edited: Oct 17, 2008
  10. wrxplayer

    wrxplayer Supporting Member

    Messages:
    5,823
    Joined:
    Jan 2, 2008
    Location:
    Somerset County, NJ
  11. zzmoore

    zzmoore Member

    Messages:
    6,278
    Joined:
    Sep 22, 2006
    Location:
    USA, California, 94585
    These types of mods work pretty well, and you can always turn them around if they do not suit you. As far as it costing $25.00...... I can't imagine a tech would even turn on his soldering iron for $25.00. If a tech does it for that price they are doing you a favor, and there is nothing wrong with that. :cool:
     
  12. dvnator

    dvnator Member

    Messages:
    42
    Joined:
    Jun 27, 2008
    I think I know exactly what this mod is.
    He says you need 3 resistors, 2 you already have. I think he got the 2 resistor swap from here...
    http://dnator.50webs.com/index.html
    On a v33 it's R4/R77, on a V18 it's R4/R10.
    The other thing he mentions is that it will change the clean channel and the tone controls will be more effective. That sounds like he is changing the value of the slope resistor, R18. Probably bumping it up to somewhere between 68k-100k.

    Schematic is here..
    http://www.blueguitar.org/new/schem/misc_amp/crate_v18_corrected_drawings.pdf
     
  13. Helder22

    Helder22 Member

    Messages:
    14
    Joined:
    Oct 20, 2008
    OK I just tried swapping my R4 for my R10 I didnt touch my R18.
    I LOVE IT LOVE IT LOVE IT !
    the muddiness is gone. The muddiness was the only big problem I was having with this amp and now its gone! I set all my EQ dials to 12 o'clock and it just sounds perfect that way. Of course ill adjust it as its just a starting point but I already like it !

    Question is: is there any chance that this mod will harm my Amp in any way? Its my only amp so Id like to keep it working, hehe.

    BTW the tape trick on the springs does wonders too. Just wrap a 1/32" strip of black tape around the springs about 1.5 inches from one of the ends and it will bring that reverb under control. I just cut a 1/32" strip from a roll of black electric tape and wrapped it around. Looks like a little ring around the spring thats all, very small. If you dont like it just take it off.
     
  14. dvnator

    dvnator Member

    Messages:
    42
    Joined:
    Jun 27, 2008
    It won't harm the amp.
    Basically, with this mod the second gain stage is not hit as hard. It lowers the gain there.
     
  15. Marshall Man

    Marshall Man Member

    Messages:
    1,107
    Joined:
    Jan 7, 2008
    Location:
    Tampa Florida
    I think I'm going to try this swap since it sounds like ****. Thanks.
     
  16. Marshall Man

    Marshall Man Member

    Messages:
    1,107
    Joined:
    Jan 7, 2008
    Location:
    Tampa Florida

    I tried to do the resistor swap and screwed up the R4/R10 resistors; I need to buy the two resistors, can anyone tell me what they are and does someone like Radio Shack carry them?

    Thanks for the help!
     
  17. myfoot

    myfoot Member

    Messages:
    60
    Joined:
    Jul 30, 2007
    Location:
    Illinois quad cities
    R4 is 2.2m and R10 is 470k . I would think Radio Shack would carry those values.
     
  18. Marshall Man

    Marshall Man Member

    Messages:
    1,107
    Joined:
    Jan 7, 2008
    Location:
    Tampa Florida
  19. TomC

    TomC Member

    Messages:
    6
    Joined:
    Aug 19, 2005
    Location:
    Everett, WA
    Part numbers: 2.2M - 217-007
    470K - 271-1133

    Good luck.
     

Share This Page