Crate V18: Mods and Conversions

Discussion in 'Amps and Cabs' started by steeve_a, Nov 15, 2008.


  1. sailsguy

    sailsguy Member

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    I've been following this thread for a while. I purchased my son 2 V18 212 and 1 V18 112. I am doing the simple modifications for the moment of swapping R4 and R10 and putting 100K into R18, accutronics reverb and replacement speakers (Red White Blues on the 112 and Screamin Eagles on the 212).

    I finished the first mod on the 112, and it sounds great. I broke the 2.2 M resistor on the first 212 mod I tried and thought I would temporarily switch the 2.2 M from the other 212 I had. When I opened it up the board is different. R4 is in a slightly different place and has an additional resistor plugged into it on one end.

    I think I'll just get another 2.2 M to replace the one I broke for the time being. But, what is the different board about? Can I make the same mods on it?

    Also, wondering if I should try a different mod to the last 212 anyway.

    New to posting, but have been reading for a while. I have experience from years ago on circuit board soldering, but acutally am a woodwind player trying to get my son some good sounding gear.

    Comments appreciated.

    -sailsguy
     
  2. steeve_a

    steeve_a Member

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    So one V18-212 had the same board as the V18-112 and one didn't? I haven't seen any of the 212's, just the 112's.

    If you have trouble finding a 2.2M resistor you can wire two 1M resistors together in series and that should be close enough for rock'n'roll.

    Radio Shack used to sell those bags of 1/4 watt and 1/2 watt carbon film resistors, which is a cheap way to get an assortment of various values. Do they still make that cardboard piece that shows the color codes for the different values- with the wheels that you spin around? Very handy (but I ohm them out, too, just to be sure!)

    Good luck!

    Steve Ahola
     
  3. scihibmxer@juno

    scihibmxer@juno Member

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    When I saw the board on our v18-212, I actually thought someone had try to mod it, since it was a scratch and dent. Both the 68K resistors, and the bridging cap to anode on v1b were tacked on top of the tube legs. Then I noticed other differences around v1. There is an empty cathode cap position (v1b) on the board, C8. Our v50 has a similar board. This must be an earlier version of the board (no where does this board say v18-112, 212, or any other v series numbers). Everything after v1 appears the same on both boards. It will make the SLO mod on this one just a little more work at v1.

    Manufacture date codes of 18706 for the old versions, new versions boards were in the v33H 18707 and v18-112 18708.
     
    Last edited: Dec 29, 2008
  4. sailsguy

    sailsguy Member

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    Thanks guys for the responses. I guess will do something different with the third V18. From what I am reading here the Soldano mod would be a popular choice. My son plays a lot of Hendrix style things. Also plays a lot of originals, all in a classic rock or metal style. Plays a Les Paul and a Strat mostly.

    sailsguy
     
  5. steeve_a

    steeve_a Member

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    sailsguy:

    If you run into any problems you might want to take some digital pix and email them to me at steve (at) blueguitar.org

    With there being differences on the boards you probably want to step through the audio signal path with a DMM while looking at the schematic and the factory layout drawing.

    It might sound like a hassle but your son will be rewarded with many hours of pleasure playing the amp.

    Good luck

    Steve Ahola

    P.S. If he plays both a LP and a strat you probably want to wire up the 0.001uF Bright cap to a switch. I don't recommend putting a mini-toggle switch on the top panel because it could be broken very easily in transit. One option would be a small push-on push-off switch on the top panel; otherwise you could install any style of switch on the bottom panel but be sure to use shielded cable.
     
  6. rock_mumbles

    rock_mumbles Member

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    The V18-212 we have has a date code of (OM)18706 the V18-112 has a date code of (OM)18708.

    So far all of the parts look the same, the two are just put together different to get the same end product. I labeled a picture that has the add-on parts around V1. Note: R65 is the tiny resistor from pin 7 of V1 to R4.


    [​IMG]

    BTW, the Soldano conversion is worth every bit of the time and work it takes, a friend who owns a small music store and does guitar/amp repair, played through my yet unfinished Soldano conversion and asked if I could make his Mesa DC-5 sound that good.
    [​IMG]
     
    Last edited: Dec 30, 2008
  7. steeve_a

    steeve_a Member

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    Thanks for posting the pictures! It looks like Crate had an earlier board that required a few mods. The earlier design must have had hella gain, with the C8 Ck cap on V1b... :roll I think that they must have tacked on C10 to help reduce oscillations, although it is more common to see it installed between the plate and the cathode.

    Have a Happy New Year!

    Steve

    P.S. If the DC-5 has the same preamp as the DC-2 it looks like you could Soldano-mize it fairly easily- although soldanomy is still illegal in several states so that might present a problem. :crazy
     
    Last edited: Dec 30, 2008
  8. wagdog

    wagdog Member

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    Well, I made the SLO mod to my v33h - came out GREAT. I put the details in a thread over at harmony central: http://acapella.harmony-central.com/forums/showthread.php?p=31965195

    if anyone is interested in the details. I want to again thank Steve for his work on the v18 (especially 'cause my v18 now sounds great too!).

    I didn't do the power amp mods to the v33 as was done on the v18 and also left in the mid-boost and presence boost in the v33 - still sounds fantastic. Here is a clip of the amp:

    http://wagner-usa.net/cratev33SLO-74strat_mixdown01.mp3

    Thanks again Steve and Happy New Year to all here!
     
  9. RussB

    RussB low rent hobbyist Silver Supporting Member

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    Here's the modified schematic of where my V18 is at right now (subject to change at any moment!)

    R2 - 820 ohms (cathode resistor, V1A)

    C6 - 1uf (cathode bypass cap, V1A)

    V1A connects to CW1 via a .001uf (600v) cap, with a 470k 1w resistor to ground

    R3 - 100k (plate load resistor, V2B)

    C7 - .01uf (coupling cap)

    C13 - .68uf (cathode bypass cap, V2B)

    C12 - 250pf (treble tone/coupling cap in tone stack) not noted on the schematic, Oops!

    C21 & C22 - .01uf Orange drop 715's (PI coupling caps)

    I've also replaced the stock input jack with a switchcraft

    I have a Hellatone 60 (aka Celestion Vintage 30) in there, and the bass is NOT overpowering. The speaker sounds very good, but cranked up, it rattles the BeJesus out of my electric heat registers! All these mods have changed the character of the amp significantly, and in a very good way!


    [​IMG]


    I appologize that the scan is so small and illegible. I could email a bigger copy if anyone wants one :cool:
     
  10. RussB

    RussB low rent hobbyist Silver Supporting Member

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    [​IMG]


    I also have the accutronics R4EB2C1B reverb tank installed
     
  11. steeve_a

    steeve_a Member

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    I read your posts over at Harmony Central. I think that you could have left the relays in place and just replaced the parts as in the V18. By doing that you could have still had a Clean channel, although it probably would not have been crystal clear with a lot of chime...

    BTW I am adding a channel switching relay to my Number Four V-18... I have it all drawn up to convert it into a D*mble ODS and will get started on it now that the holidays are over. (I posted the details and the preliminary drawings over at ppwatt.com)

    Steve Ahola

    P.S. I put the mid-boost circuitry back in my Soldano V-18- I thought it sounded better with it back in. I guess I need to edit the initial post here since I changed a few of the values- my bad!
     
  12. scottyray1970

    scottyray1970 Member

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    Anybody have advice on a decent prelacement speaker for the crate
    v18 112? I've been looking into some Jensens but i only came accross 50w
    speakers. Will those work?
     
  13. rock_mumbles

    rock_mumbles Member

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    Hi Steve, I just finally got the parts put in to "complete" the Soldano Conversion last night. I replaced R43, R44, R45, R46, added the cap across R11, and did the reverb fix (my R38 was a 100K stock). Previously I had only done the preamp conversion.

    Since I don't understand what I'm doing ... what effect do the value changes in R46-R44 and R45-R43 do to the power amp?

    Are the power amp tubes being run harder now?
     
  14. steeve_a

    steeve_a Member

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    R45 and R46 are the grid loads for the EL84 output tubes. Most amps use a grid load of 220k but the V18 and V33 uses the grid load of 470k from the Marshall 18 watter which will push the EL84's harder. So replacing the 470k resistors with 220k resistors will not push the EL84's as hard. If there is not a lot of gain in the preamp (like in a vintage 18 watter) then I think that 470k resistors would be fine but the Crate V-series amps have gain coming out of the wazoo! ;)

    R43 and R44 are the grid stoppers and I think that a lower value like 2k2 is more common than the 10k value used by Crate in these amps. A higher value tends to muffle the high end a bit so when I put in the 2k2 grid stoppers I also like to add in a "Cut" control on the bottom panel so that I can fine-tune the amount of brightness in power amp section to match the speaker I am using.

    The layout drawings show how to reconfigure the leads for these resistors so that they are as the schematic shows (which is the same for 99% of the schematics out there). But I was informed that it doesn't make that big of a difference even though it is technically wrong on the factory pcb.

    The Cut control is a 250k pot wired as a variable resistor in series with a 0.0047 to 0.0056uF cap- the two leads can be connected to the pads for C32 which is not used in any of the V18's that I have seen. I like to put the Cut control on the bottom of the chassis between the Line Out and the reverb jacks.

    Steve Ahola
     
  15. steeve_a

    steeve_a Member

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    50 watts should be fine since the amp only puts out about 18 watts. Jensens should be okay with the stock amp since they should be brighter than the stock speaker.

    I know that a lot of people are putting in Celestion Vintage 30's which has more mids and less highs than a typical Jensen. Or a Celestion Greenback which has more highs than the Vintage 30... or something like that! ;)

    Warehouse Guitars sells great Celestion clones assembled in the US. I like the Eminence Patriot line of speakers, too. Musicians Friends usually has deals going for free shipping if you spend enough money, so you might want to look at their stock of Celestion and Eminence speakers.

    Good luck!

    Steve Ahola
     
  16. wagdog

    wagdog Member

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    Agreed. The more I thought about it, the more I felt I could have left it... but I didn't want to mess with the simplicity of the design, and I never used the clean "channel" anyway.

    I was wondering about the poweramp mods, but I see you answered that below. I noticed that the board and the schematic didn't match, and that the schematic was like most power amps I'd seen. I didn't make the power amp changes in my v33h, and it sounds fine and doesn't appear to be overdriving the poweramp, so I'm just going to leave it.

    I, like you, put the mid boost back in below the tone stack in the v18 (removing the jumper). I think it makes the tone controls more responsive. The v33 has an additional mid-boost circuit on a switch there as well.

    That sounds awesome. I almost picked up a used v18 1x12 the other day, but decided against it and bought another guitar. :)
     
  17. rock_mumbles

    rock_mumbles Member

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    Thanks, I was going by ear and it sounded like I lost some of the clean but I was not using my normal Tele test guitar so it didn't sound like I'm used to it sounding.

    I did reconfigure the grid resistors as per your instructions, the amp was used tonight at our local neighborhood blues restaurant and it worked really well with my Squire CV 50's Tele. Our guitar player realized that for this kind of gig it is a better amp than his Dean Markley 60 watt dual 6L6 amp (which is too clean and easily gets way too loud for this venue).

    So last night while finishing the conversion, I removed the bright cap from the gain pot and added the conjunctive filter from the Rocket conversion, the sound of the amp is better with my Tele now, it's still bright (it's a Tele stupid) but not over the top bright. Now I just need to drill a couple of holes in the chassis, one for the bright switch and one for the cut filter and this project may be done as far as the soldering iron goes. (yeah right)

    Steve, thanks again for the feedback and interest in our (science) projects, I don't want to just cook-book the mods and conversions, I want to learn and understand what I'm doing and you're a good teacher! :AOK
     
  18. zombiwoof

    zombiwoof Supporting Member

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    I got a mint broken-in Celestion Silver Series V12-60(made in England) on Ebay for my V18 for $35. It sounds great, and I'm considering getting the original over-doped Crate speaker reconed with a British cone to see how it compares. Anybody tried reconing the original speaker, I'd like to know if it's worth the effort?. The frame and magnet assembly look decent, I think reconing might be a good option.

    Al
     
  19. richey88

    richey88 Member

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    I would like to do this too.....right now I have 12AU, a JJ ECC83 and an NOS RCA 12AT in the pre and a Vox/Celestion from a busted ass AD50VT (speaker nicely broken in,) sounds (.)(.)!! Hate to see the over-doped go to waste (it's in the AD50VT shell and my SCXD is pushing it for gigs).
     
  20. steeve_a

    steeve_a Member

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    Were you planning on reconing it yourself? I have a friend who gets the recone kits but I have never tried it myself.

    Let us know how it works out!

    Steve Ahola
     

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