Link to easy build switchable 1959 to 2203

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neikeel
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Link to easy build switchable 1959 to 2203

Post by neikeel » Wed Jan 13, 2010 1:35 pm

Thanks to SDM for the switchable concept and doing all the artwork (all I did was rearrange slightly).

It is a Metro 100 watt kit built to 68 spec. incorporating a PPIMV a low voltage switch and a push-pull switch for 1959 to 2203. Dime the pre-PIMV with switch in and you have a 12000 spec. 1959 with a PPIMV to tame it or dime the PPIMV and use the stock Marshall type pre-PIMV for a 2203 with lowered filtering.

Premise is to have an easy mod to have a Metro you can change tones mid gig and have easy control. Minimal parts and rewiring needed (a 1meg/DPST push pull, a 10k resistor and a length of shielded wire) obviously the dual voltage and PPIMV need their bits too.

http://home.comcast.net/~jbjdav26/Neil% ... 202in1.pdf

Thanks again to Steve 8)
Neil

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Re: Link to easy build switchable 1959 to 2203

Post by papawoofer » Sun Jan 17, 2010 7:05 am

I am putting the final touches on the exact same amp except it's footswitchable using Mojo's opto switcher, sounds like your turning up your volume knob on your guitar when switched. :D Steve was a big help and a very willing teacher.
GARY

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Re: Link to easy build switchable 1959 to 2203

Post by Icarus » Wed Feb 24, 2010 5:57 am

Hi Neil
Im really interested in this mod I sent you a PM asking some questions if you dont mind

Cheers
Marshall 1973 PTP
Marshall 1977 JMP 2204
Marshall Plexi Reissue
Marshall JCM 800 1959
Marshall 1982 JCM 800 2203
Mesa Boogie MKIV

Marshall 1960TV
2x12 V-30's
Eminar 4x12
2x12 Celestion Gh-80's

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Re: Link to easy build switchable 1959 to 2203

Post by neikeel » Wed Feb 24, 2010 7:04 am

pm sent!
Neil

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Re: Link to easy build switchable 1959 to 2203

Post by demonufo » Sat Mar 06, 2010 4:34 am

So I take it that this layout doesn't cater for the hi-input in 2203 mode, or am I missing something? (very likely :lol: )
I'm certainly interested in trying something different, but don't think I can live without my standard 2203/2204 hi channel.

Not sure whether or not I've got the balls for a 100watter either, so I might have to build a 50. :oops:
So I like purple, okay!!!!!!

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Re: Link to easy build switchable 1959 to 2203

Post by neikeel » Wed Mar 17, 2010 3:40 pm

demonufo wrote:So I take it that this layout doesn't cater for the hi-input in 2203 mode, or am I missing something? (very likely :lol: )
I'm certainly interested in trying something different, but don't think I can live without my standard 2203/2204 hi channel.

Not sure whether or not I've got the balls for a 100watter either, so I might have to build a 50. :oops:
Oh yes it certainly does (there would not be any point without that channel option:wink: )!

Plug into high normal channel, with pot in and pre-mv all the way up you get stock 1959 superlead, just use Larmar to tame volume (or attenuator or wreck your ears).
Stay plugged into same input and pull the pot out you get cascaded V1. To get stock 2203 you crank the Larmar and use the pre-master as usual 2203/4 and the gain pot as usual. Again you can use the Larmar a little too. You can use the low 1959 input if you want but you have to plug the guitar into that input, same with the low 2203/4 if you like a cleaner sound.

I have a couple of pics of the mod installed in an SLP that has been modded to C1998, dual voltage, C1999 choke, metro board with mustards, 12 series filtering, Larmar PPIMV and SDM.s no loss effects loop.
Image
Image

I am in the process of modding my Plexi 2204 to the same spec and my SIR#39 will employ exactly the same preamp but with another push-pull pot to engage the fourth gain stage like this one :twisted:
http://forum.metroamp.com/viewtopic.php?f=3&t=30511

Image
All the tones you want in one amp (- well almost :wink: ).
Neil

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Re: Link to easy build switchable 1959 to 2203

Post by demonufo » Thu Mar 18, 2010 6:00 am

Hmm, guess I'll be looking for a suitable chassis later on in the year then, once I've sold a load of gear. :evil:
Give me more work, whydoncha! :lol:
Oh well, at least I got the VJ rebuild out the way. Just need to find some suitable marshally style faceplate material now.
So I like purple, okay!!!!!!

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Re: Link to easy build switchable 1959 to 2203

Post by peterc52 » Mon Apr 11, 2011 10:11 am

Has anyone tried this mod?

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Re: Link to easy build switchable 1959 to 2203

Post by neikeel » Mon Apr 11, 2011 12:59 pm

I have modded three amps (two 100w and one 50w) and built one with it from scratch, but then I am biased so you probably will not believe me :wink: .

The first layout was designed simply to mod an existing Marshall amp to give it a switchable gain boost with the minimum of rewiring so that you could restore it back to stock quickly and easily. It gives you NMV hi and lo and MV hi and lo swithcable. On a couple of amps I put a Lar-Mar type PPIMV on the back panel to help balance the volumes better, on the latest it is on the front in the tremelo spot.

If you are scratch building I would use SDMs layout as it takes the signal from left to right from V1a to V1b and to V2a etc. I would use shielded wires in both grid runs and a 500pF ceramic cap on the plates of the second stage (particularly if you are adding a 0.1uF bypass cap on the 10k or dropping the value of the 10k to 8k2, 5k6 or 4k7 for more gain).

On latest build in a Trem chassis (first proper test last night) I used 2203 inputs with shielded wires and grid stopper on V1a with 0.68uF/2k7 cathode and 0.01uF coupler so I have almost stock 1959 high channel 1. Then using the gain pot located in the hi bright hole (switched as per SDM scheme ) through the 470k/470pF cascade on the jack onto 0.12uF/10k cathode with 0.022uF coupler with pre-PIMV on the bright channel pot.
This has plenty of gain and sounds great, you can max the Pre-MV for NMV tones or max the PPIMV and use the premaster/gain balance for 2203/SIR#34 tones (although this amp is set up for EL34s). The extra gain stage (SIR#39 spec) is switched via a DPDT in the bright channel low hole with shielded wires and a plate bypass cap. This stage is isolated from the rest of the preamp by additional 10k dropper and dedicated 22uF filter cap.
I put a resonance mod and PPIMV in the trem controls. On the back is an SDM no loss loop.
I will ask SDM if he can put this on a layout as I think that is probably the ultimate Hot Rod Marshall (but I guess you have all heard that before :roll: ).
So far no squeals or PO but some hiss on the four stager with the gain cranked.
:hairband:
Pics to follow :wink:
Neil

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Re: Link to easy build switchable 1959 to 2203

Post by peterc52 » Mon Apr 11, 2011 1:14 pm

Hi Neikeel, :)

I've made this topic: http://forum.metroamp.com/viewtopic.php?f=4&t=35304" onclick="window.open(this.href);return false;

I thinking about doing your mod to a Marshall 1959 '81.

What say you?

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Re: Link to easy build switchable 1959 to 2203

Post by peterc52 » Mon Apr 11, 2011 1:17 pm

Image

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Re: Link to easy build switchable 1959 to 2203

Post by neikeel » Mon Apr 11, 2011 1:30 pm

peterc52 wrote:Image
Do not show that PPIMV installation to Larry - he might have kittens :lol:

I think the mod will work well but I would suggest moving the MV control either to the presence spot and moving presence to one of the speaker jacks or if you use the presence control a lot put the MV on the back.

When you have done the mod do you intend modding further? If not you can simply follow the mod I listed.

If you are I suggest that you remove two of the input jacks with their wires and keep them safe. Then rewire the remaining jacks like a 2203 but use shielded wire from them to a 33k grid stopper onto V1 socket. Replace the 820R and 330uF caps with 10k and 0.1uF and use shielded wire from V1b back to the dedicated switch/gain pot. For now put a rubber bung in the unused input hole (you may need this later if you decide to add extra stage) or by all means use it as your PPIMV control if it remains quiet but don't tell Larry :lol:
Neil

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Re: Link to easy build switchable 1959 to 2203

Post by MacGaden » Mon Apr 11, 2011 1:35 pm

neikeel wrote:I have modded three amps (two 100w and one 50w) and built one with it from scratch, but then I am biased so you probably will not believe me :wink: .

The first layout was designed simply to mod an existing Marshall amp to give it a switchable gain boost with the minimum of rewiring so that you could restore it back to stock quickly and easily. It gives you NMV hi and lo and MV hi and lo swithcable. On a couple of amps I put a Lar-Mar type PPIMV on the back panel to help balance the volumes better, on the latest it is on the front in the tremelo spot.

If you are scratch building I would use SDMs layout as it takes the signal from left to right from V1a to V1b and to V2a etc. I would use shielded wires in both grid runs and a 500pF ceramic cap on the plates of the second stage (particularly if you are adding a 0.1uF bypass cap on the 10k or dropping the value of the 10k to 8k2, 5k6 or 4k7 for more gain).

On latest build in a Trem chassis (first proper test last night) I used 2203 inputs with shielded wires and grid stopper on V1a with 0.68uF/2k7 cathode and 0.01uF coupler so I have almost stock 1959 high channel 1. Then using the gain pot located in the hi bright hole (switched as per SDM scheme ) through the 470k/470pF cascade on the jack onto 0.12uF/10k cathode with 0.022uF coupler with pre-PIMV on the bright channel pot.
This has plenty of gain and sounds great, you can max the Pre-MV for NMV tones or max the PPIMV and use the premaster/gain balance for 2203/SIR#34 tones (although this amp is set up for EL34s). The extra gain stage (SIR#39 spec) is switched via a DPDT in the bright channel low hole with shielded wires and a plate bypass cap. This stage is isolated from the rest of the preamp by additional 10k dropper and dedicated 22uF filter cap.
I put a resonance mod and PPIMV in the trem controls. On the back is an SDM no loss loop.
I will ask SDM if he can put this on a layout as I think that is probably the ultimate Hot Rod Marshall (but I guess you have all heard that before :roll: ).
So far no squeals or PO but some hiss on the four stager with the gain cranked.
:hairband:
Pics to follow :wink:
There are two links on Steve´s website called "Neils Special"

http://home.comcast.net/%7Ejbjdav26/Nei ... 202in1.pdf

http://home.comcast.net/%7Ejbjdav26/195 ... %20alt.pdf
MacG.

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My son Adam at 3 years old. Best advice I ever got..

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Re: Link to easy build switchable 1959 to 2203

Post by neikeel » Mon Apr 11, 2011 2:11 pm

Yes the alternative lead dress is Steve's clean up.

I have not had noise issues with first version as long as no gain mods. It keeps the amp labels and layout as stock, you only lose normal channel. Silly on my part but I wanted it to look and plug into as close to a stock SL as possible with a subtle extra pot asthe only clue but really if you make a custom plexipanel steve's alternative lead dress ie the one to use.
Neil

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Re: Link to easy build switchable 1959 to 2203

Post by peterc52 » Mon Apr 11, 2011 2:50 pm

Done.

http://i832.photobucket.com/albums/zz24 ... 000334.jpg" onclick="window.open(this.href);return false; :o

Would the circuit be exactly like a 2203 circuit if I'd fellow your layout?

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