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Peavey VTM Mods Lounge


Sixtonoize

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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 eBay
VTM 60 #2 - bought off CL (drove 2 hours to get it), sold to chrispsullivan
VTM 60 #3 - Bought from pioneerprogress as non-working - needs new pots and re-tube, possibly filter caps

Mods performed:

BIAS MOD - Replaced R8 with 50k pot and 22k limiting resistor
Comments:

 

Bias still too cold. Replacing 22k resistor with 5k resistor

Bias uneven - 36ma on V5, 25ma on V6

DEEP SWITCH - added two 22n caps in parallel with existing 22n bass cap in tone stack to extent low frequency response
Comments:

 

Subtle, but effective bass extension.

BRIGHT SWITCH - removes C1 from circuit
Comments:

 

Sounds good

REPLACED ALL TONE STACK POTS with Marshall-spec pots

High/Low GAIN INPUTS FOOTSWITCHABLE - harder than it sounds
Comments:

 

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 relays

5150 HEADSHELL SWAP

Mods Planned:

Bias balance mod (allow for mis-matched tubes)
External bias points
Choke mod
Screen resistor - increase to 470 ohm
Dual Channel mod - replace Pre and Post Gain with dual concentric pots switched by relays
Tonal mods - decrease bass @ first gain stage, increase in tone stack
Resonance mod - Add bass boost to presence circuit

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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...:
Picture2005.jpg

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Quote Originally Posted by Sixtonoize View Post
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.
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Quote Originally Posted by Sixtonoize View Post
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!)
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Quote Originally Posted by Guiary

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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?
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Quote Originally Posted by Sixtonoize

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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.thumb.gif
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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.

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Here's a sweet mod, courtesy of Ryan_F:

Quote Originally Posted by Ryan_F View Post
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.
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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.

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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 facepalm.gif...but I plan on taking care of that later, unless I can make do with shielding.

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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?

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