Members Sixtonoize Posted March 26, 2009 Members Share Posted March 26, 2009 The VTM series are killer amps with a devoted following and are an awesome platform for modding.I think it's time that we have a place to show off our work.If you've done tonal mods, post clips. If you've done cosmetic mods, post pics.Gut shots are badass, too.Personal VTM history:VTM 60 #1 - bought off eBay, replaced Presence pot, sold on eBayVTM 60 #2 - bought off CL (drove 2 hours to get it), sold to chrispsullivanVTM 60 #3 - Bought from pioneerprogress as non-working - needs new pots and re-tube, possibly filter capsMods performed:BIAS MOD - Replaced R8 with 50k pot and 22k limiting resistorComments: Bias still too cold. Replacing 22k resistor with 5k resistorBias uneven - 36ma on V5, 25ma on V6DEEP SWITCH - added two 22n caps in parallel with existing 22n bass cap in tone stack to extent low frequency responseComments: Subtle, but effective bass extension.BRIGHT SWITCH - removes C1 from circuitComments: Sounds goodREPLACED ALL TONE STACK POTS with Marshall-spec potsHigh/Low GAIN INPUTS FOOTSWITCHABLE - harder than it soundsComments: Works well, but not as well as it would if I made the Gain and Master switchable as well.Replaced the Low gain input with a panel-mount jack to control the relays5150 HEADSHELL SWAPMods Planned:Bias balance mod (allow for mis-matched tubes)External bias pointsChoke modScreen resistor - increase to 470 ohmDual Channel mod - replace Pre and Post Gain with dual concentric pots switched by relaysTonal mods - decrease bass @ first gain stage, increase in tone stackResonance mod - Add bass boost to presence circuit Link to comment Share on other sites More sharing options...
Members JerryP Posted March 26, 2009 Members Share Posted March 26, 2009 The VTM is a very under rated amp! Jerry Link to comment Share on other sites More sharing options...
Members Guiary Posted March 26, 2009 Members Share Posted March 26, 2009 I've done some mods to it which I'll have to look up to see what was done again (wanted it tighter and more aggressive), and I had help from a few of the board members (thanks again to those who helped!!!)Cosmetic mods...: Link to comment Share on other sites More sharing options...
Members Guiary Posted March 26, 2009 Members Share Posted March 26, 2009 Originally Posted by JerryP The VTM is a very under rated amp!Jerry Hell Jerry!!!Great Job!Love those first two vids! Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted March 26, 2009 Author Members Share Posted March 26, 2009 Originally Posted by Guiary (wanted it tighter and more aggressive) That's exactly what I'm looking for out of mine.And your VTM looks KILLER, Gary! Link to comment Share on other sites More sharing options...
Members I-like2play Posted March 26, 2009 Members Share Posted March 26, 2009 Noob question sorry. Can you run just two power tubes in the 120? Link to comment Share on other sites More sharing options...
Members Guiary Posted March 26, 2009 Members Share Posted March 26, 2009 Originally Posted by Sixtonoize That's exactly what I'm looking for out of mine.And your VTM looks KILLER, Gary! When I get around to things again I'll send you a clip of how the VTM sounds now and give you my mod list. Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted March 26, 2009 Author Members Share Posted March 26, 2009 Originally Posted by Guiary When I get around to things again I'll send you a clip of how the VTM sounds now and give you my mod list. How do you like the MM tranny and choke? Link to comment Share on other sites More sharing options...
Members "sasquatch" Posted March 26, 2009 Members Share Posted March 26, 2009 i don't think it really needs anything other than maybe snipping the bright cap. that's it. sounds great, as is, especially through some well broken in GT-75s Link to comment Share on other sites More sharing options...
Members pioneerprogress Posted March 26, 2009 Members Share Posted March 26, 2009 Originally Posted by Guiary I've done some mods to it which I'll have to look up to see what was done again (wanted it tighter and more aggressive), and I had help from a few of the board members (thanks again to those who helped!!!)Cosmetic mods...: Looks great! Link to comment Share on other sites More sharing options...
Members Guiary Posted March 26, 2009 Members Share Posted March 26, 2009 Originally Posted by Sixtonoize How do you like the MM tranny and choke? I like the improvements with the tranny and choke... Really like the choke!It really helped with note clarity and helped with tightening up that low end; although in all fairness I'm not too sure I'd go with MM next time if I were to do this mod on this amp again. I think I should have tried Heyboer or Hammond and when I get bored again I may just try other companies chokes and see what the difference is (chokes are cheap!) Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted March 26, 2009 Author Members Share Posted March 26, 2009 Originally Posted by Guiary I like the improvements with the tranny and choke... Really like the choke! I was thinking about doing the choke mod on mine...you just replace R5 (the long, skinny blue resistor on the power board) with the choke, right? Link to comment Share on other sites More sharing options...
Members Guiary Posted March 26, 2009 Members Share Posted March 26, 2009 Originally Posted by Sixtonoize I was thinking about doing the choke mod on mine...you just replace R5 (the long, skinny blue resistor on the power board) with the choke, right? I hope so! That's where I put it. Link to comment Share on other sites More sharing options...
Members Ryan_F Posted March 26, 2009 Members Share Posted March 26, 2009 Yes, you can run two power tubes on the 120. I did for a few practices, It doesnt help at all. Mods So far: 1. Replaced all EL caps 2. footswitchable pre/post gain pots, changed some resistors on one channel to make it "clean" 3. Changed resistor on preamp board (don't know without schematic in front of me) to change the "grainy-ness" or saturation level of distortion. 4. replaced front panel with plexiglass Planned Mods 1. Illuminate amp, along with etch something in plexiglass 2. install only one input jack and make it footswitchable to go between lo/hi inputs. 3. screw with other stuff. Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted March 27, 2009 Author Members Share Posted March 27, 2009 Do you have any pics of the plexiglass mod? That sounds sweet. And for anyone interested, here's the schematic:http://schematicheaven.com/newamps/peavy_vtm_120.pdf Link to comment Share on other sites More sharing options...
Members Ryan_F Posted March 27, 2009 Members Share Posted March 27, 2009 I don't have any pictures currently. So far its just a piece of plexiglass with 4 screws holding it in. No etching or lighting yet. I'll snag a pic in a week or two when I can get to my amp. Link to comment Share on other sites More sharing options...
Members 10-46 Posted March 28, 2009 Members Share Posted March 28, 2009 Curious what value anyone has used for a choke? (5H, 10H, etc). Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted March 28, 2009 Author Members Share Posted March 28, 2009 Updated my mods section. The Deep mod is cool, but it needs to be more apparent...I'm thinking I need to bump up the total capacitance to around 100n to get the bass extension I'm looking for. Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted March 31, 2009 Author Members Share Posted March 31, 2009 Here's a sweet mod, courtesy of Ryan_F: Originally Posted by Ryan_F I also changed one resistor that someone suggested at musicelectronics forum. I dont remember, but it controls the grainy-ness of the distortion. It's R2 on the preamp board, Its a 100k, 1W located next to V1. Replace with 220k or 330k. Its a really nice, quick mod to do. I mounted a switch on the front panel to switch between them on the amp. Link to comment Share on other sites More sharing options...
Members Ryan_F Posted March 31, 2009 Members Share Posted March 31, 2009 Yay! I did something good! Depending on what kinda music I'm playing, I like to use different values for this resistor. They aren't night and day differences, but its a subtle effect, probably more noticeable by the player than the listener. I'm going to dig up my schematics for the Footswitchable 2nd channel this weekend. I'll post it up here when I can. Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted April 1, 2009 Author Members Share Posted April 1, 2009 I just got done doing my own footswitchable channel mod - I didn't add any extra pots, I just rigged it up so that you can switch between the Hi and Low inputs on the fly. It actually works surprisingly well and the channels are pretty well balanced, IMO.There's a fair amount of noise...mostly because I put the rectification circuit on the same board as the relays ...but I plan on taking care of that later, unless I can make do with shielding. Link to comment Share on other sites More sharing options...
Members Ryan_F Posted April 1, 2009 Members Share Posted April 1, 2009 When I did the footswitch between the pre/post pots, I used only shielded cable (after it had terrible noise with unshielded). Now there is no more noise than stock. Got a rough drawing of the layout for your input switch mod? Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted April 1, 2009 Author Members Share Posted April 1, 2009 I could probably put something together...I'll see what I can do. Link to comment Share on other sites More sharing options...
Members Ryan_F Posted April 1, 2009 Members Share Posted April 1, 2009 Thanks. I think I have a drawing for it somewhere, but It was very poorly done. Might be a good resource to post in this thread as well. Link to comment Share on other sites More sharing options...
Members Sixtonoize Posted April 1, 2009 Author Members Share Posted April 1, 2009 Where did you get your shielded wire? Link to comment Share on other sites More sharing options...
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