Stout 6V6 Chassis- JCM-800/2203 High Gain Mod5

[topbrent]

Here is a fun high gain modification for the little 6V6 Stout chassis project.  This is an adaptation of the great sounding Mod5 that was developed by Mark Abrahamian (RIP) who was the guitarist for Starship and was a fixture of the EVH sound over on the Metroamp forum.  He wanted to have the early Van Halen sound at a lower volume.  Mark succeeded in his endeavor.
   
Very simply, it consists of a few easy modifications to the standard Marshall 2203/JCM800 front end with the addition of the LarMar master volume.

This mod only requires a few extra turrets in the existing Hoffman Stout Plexi 6V6 board and doesn't require any extra holes in the chassis.

This should make for a compact and fun little package! 

- Brent

[topbrent]

Here are a few examples of this the Mod5 version of the 2203.


Examples of the Mod5:Rockstah Mod5™ www.rockstahamps.com Clip #3Rockstah Mod5™ www.rockstahamps.com Clip #4Rockstah Mod5™ www.rockstahamps.com Clip #5Marshall JCM 800 Mod 5

[Glennjeff]

Hi topbrent,

You wouldn't happen to have a link to the schematic for this mod would you.
I'm just too old to learn new tricks like overlays.

All the best

[kagliostro]

I've find this

http://cfile26.uf.tistory.com/image/2623AD4B51A5685928B8E4



I'm waiting the confirm that it is the right schematic, from Topbrent, here

http://el34world.com/Forum/index.php?topic=18338.new#new

K

[topbrent]

I used this schematic, which varies only slightly from the one posted by K.

[Glennjeff]

kagliostro & topbrent,

Thanks heaps.

[VMS]

Thanks Topbrent for sharing this. Few questions:

How does this sound on bedroom level (does it give the brown sound)?

Do you dime the volume after tone stack and use the lar-mar as a master volume?

...or what are your preferred settings?


thanks in advance

-v

[ismacdon]

Curious to know if anyone has actually built this design, and if so, how'd it turn out?  I'm amassing my parts for a 6v6 marshall style build.

Thanks.

[Big_Mike]

I am thinking of building a 6v6 Plexi myself and really want to try putting a ppimv on it...this diagram really helps.  One question - should the resistors on the dual gang master pot be 220K instead of 2.2M?  That is usually what I see on a standard lar-mar.

[TIMBO]

2.2M is correct.

[Big_Mike]

For a Rich Mod PPIMV, would I omit the 2.2M resistors and have the stock 100k resistors coming off the center lugs for the dual pot?  In comparing the Rich Mod PPIMV on the valvestorm site, that would seem to be how it would be wired for Hoffman's 6v6 Plexi.  The Rich Mod uses a dual 500K pot.

[purpletele]

Here is a fun high gain modification for the little 6V6 Stout chassis project.  This is an adaptation of the great sounding Mod5 that was developed by Mark Abrahamian (RIP) who was the guitarist for Starship and was a fixture of the EVH sound over on the Metroamp forum.  He wanted to have the early Van Halen sound at a lower volume.  Mark succeeded in his endeavor.
   
Very simply, it consists of a few easy modifications to the standard Marshall 2203/JCM800 front end with the addition of the LarMar master volume.

This mod only requires a few extra turrets in the existing Hoffman Stout Plexi 6V6 board and doesn't require any extra holes in the chassis.

This should make for a compact and fun little package! 

- Brent

Brent/All,

I built this amp the last few days and it came out fantastic!!

This is the real deal Van Halen Brown Tone in an 18 watt package.

The Master Volume works incredibly well.

The details that Brent did on the Hoffman Layout are accurate, or I made some lucky mistakes, this thing just rocks.

I cannot express how pleasant it was to turn on the amp with the light limiter in place and have zero issues.  I set the bias at 21.7 with a plate voltage of 386 V, and I have been just ripping all morning through a pair of greenbacks.

Video and audio soon.

BV

[Big_Mike]

Nice build, how is the Lar/Mar master at low volumes?

[purpletele]

Nice build, how is the Lar/Mar master at low volumes?

I just filmed a video, but I'm not sure if I picked up the significance of the MV.


This particular MV is absolutely incredible, as good as I have ever played.  I think my workmanship is getting better but the amp seems to be set up perfectly for this MV.

[Big_Mike]

I am thinking of doing a standard 6v6 Plexi and subbing a Lar/Mar PPIMV in place of the standard pre phase inverter master on the Hoffman layout.  I assume the wiring would be the same?

[purpletele]

I am thinking of doing a standard 6v6 Plexi and subbing a Lar/Mar PPIMV in place of the standard pre phase inverter master on the Hoffman layout.  I assume the wiring would be the same?

Interesting topic for the moment.  My colleague just picked up my 6 V 6 Plexi Combo for a show and we were discussing the difference in the two amps with respect to the controls.


The Mod 5 included 4 turrets to the existing Plexi board, so the MV should work the same, however, I believe the Master on the Plexi drives the tone stack.  I am not sure how you would cut in the Master,  So you may want to replicate the Mod 5 controls, I'm playing it now and it is bad Arse at low volume.


I would use the modified control wiring if I built another Plexi.



BV

[Big_Mike]

Thanks so much for the info...I take it you prefer the Mod 5 to the regular Plexi circuit?

[purpletele]

Thanks so much for the info...I take it you prefer the Mod 5 to the regular Plexi circuit?

I really like the versitality of the regular Plexi.  That amp makes both single coils as well as gummies sound great.

I like the MV wiring.  The Mod 5 is cool when playing Alice in Chain love songs.  That Plexi straight up is a blues machine or a rock monster.

Plexi

[Big_Mike]

Thanks for the info.  I have heard a lot of the magic with a Plexi comes from phase inverter distortion.  I am weighing whether to go with the Hoffman 6v6 stock, or whether to add a PPIMV.  Decisions, decisions!

[sluckey]

For maximum versatility just do both. I don't use the pre PI MV on mine the way most of you guys like to use a MV. I use the two volume controls to blend the channels together for the tone I want. Then I use the MV to set the overall volume. I could probably benefit from a PPIMV too but it would have to go on my back panel. No room up front on my 12" chassis.

[Big_Mike]

For maximum versatility just do both. I don't use the pre PI MV on mine the way most of you guys like to use a MV. I use the two volume controls to blend the channels together for the tone I want. Then I use the MV to set the overall volume. I could probably benefit from a PPIMV too but it would have to go on my back panel. No room up front on my 12" chassis.

If I wanted to just go with a PPIMV in place of the stock MV, would the middle tab from the treble pot go to the .022 cap on the board that the stock master goes to?  Then add the LAR/MAR circuit as in the Mod 5 schematic above? 

I am using a Stout chassis, so I only have one hole for a master volume on the chassis.  I guess I could put it on the rear, though.

[sluckey]

If I wanted to just go with a PPIMV in place of the stock MV, would the middle tab from the treble pot go to the .022 cap on the board that the stock master goes to?

yes

[Big_Mike]

Thanks Slucky, much appreciated.

[ismacdon]

Awesome!  Just need can caps at this point.  Mine's gonna be a total frankenstein so the circuit will likely change a few times.  Thx all for the input!

[purpletele]

For maximum versatility just do both. I don't use the pre PI MV on mine the way most of you guys like to use a MV. I use the two volume controls to blend the channels together for the tone I want. Then I use the MV to set the overall volume. I could probably benefit from a PPIMV too but it would have to go on my back panel. No room up front on my 12" chassis.

After further review of the Mod 5 upgrades, I think I prefer the ability to have the Plexi Cleans available.  I may redoing it like you have suggested here and maybe add a high gain stage mod.