Vintage Modern 2266 conversion to 1987/2204 specs

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twango
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Vintage Modern 2266 conversion to 1987/2204 specs

Post by twango » Thu May 13, 2010 4:12 pm

Hi folks,

I got a VM 2266 fairly cheap on eBay but I did not really like the sound. Sounds too thin on "detail" and just muddy on "body". Mixing both gives a thin but muddy sound ... :lol:
Power amp clipping sounded poor, farting noises, some "ghosting", etc. After some comparisons with my old Marshalls I really would critisize the 2266 being just crap. :(
But the schematic shows a nice basis for modding, being very close to a JTM45 with linked inputs and switchable extra 2nd gain stage like 2204. I did a conversion to EL34 too, because I got another amp I did not like, a DSL50 tuned with a Mercury Axiom OT. I put the Dagnall from the 2266 along the KT66 into the DSL and sold the bunch luckily for the same money I paid for the DSL before... :wink:
(BTW, the KT66 were a big improvement to the DSL, make it less boomy and edgy, adding more organic mids...)
The mods getting the circuit of the VM very close to a JTM/JMP preamp, switching in the V2 getting it very close to the 2204. The differences are still the PPIMV (I pulled it too, not described below...), V2 being both triodes parallel (you can cut the socket legs on pin 1,2,3). The mid boost switch is now a gain boost for the extra stage
That´s what I did, all the work is just on the preamp board, pull tubes, a couple of connectors, 2 screws, unscrew the pots and input jack - 1 hour, conversion done...

The tonal results are VERY nice :mrgreen:

Treble Channel:

Replace C1, 220nF with 0,68uF, SoZo
Replace C2, 1nF with 22nF, SoZo
Replace C5, 330pF with 470pF Ceramic
Replace R4, 1K5 with 820R

Normal Channel:

Replace C3, 22nF with 22nF, SoZo
Remove R8
Remove R9, add 470K, link from input R8 to output R9
Replace C6 with link wire
Remove C7
Remove R88

Hi Gain:

Remove C8, 1n
Remove C9, 1uF
Replace C11, 1nF with 22nF, SoZo
Bridge R14, 470K with 470pF Ceramic
Replace R13, 1K5 with 10K
Add R 10K from Input R9 to Ground

Tone Stack:

Replace C14, 22nF with 22nF, SoZo
Replace C15, 22nF with 22nF, SoZo

EL34 Conversion:

Replace OT
Replace R67, 150K with 220K
EL34 Svetlana -C-
Biased @ 43mA

See pix for reference, have fun...
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THChrist
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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by THChrist » Sat May 15, 2010 3:17 pm

Interesting conversion. So, basically you have a 1987/2204 with 2 extra knobs, right? Got samples?

twango
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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by twango » Sun May 16, 2010 3:37 pm

Yes,
it´s the 1987-topology with normal & treble preamp pots and inputs linked plus master. the 2nd gain stage (10k cathode) can be switched in, so it´s the 2204 plus "normal preamp", gain boost can be switched too (from 10k 2nd cathode to 4k7).

I do some recordings on tuesday when my wife is out for choir... :wink:

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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by Rockbert » Mon May 17, 2010 1:43 pm

Nice work, but I think you uploaded the wrong pics, those look like the inside of a computer. Oh wait.. :mrgreen:

twango
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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by twango » Tue May 18, 2010 4:16 pm

... hehe, I´m still working on syncronizing the EL34 output to USB, maybe I have to trigger it with a bicycle-dynamo first :D

I have some short clips: guitar, amp, right channel is Shure SM57 close to speaker (15 degrees off axis), left channel is RFT DM622 80cm off speaker cab (adding some room), Edirol UA25 Interface, PC, no EQ, no FX...

Guitars are my CS Strat and my Burny 58 LP Jr. doublecut P90.

The gristle is from mp3 conversion (crap...), sorry!

Next thing I´m gonna do is to fool around with the NFB and kick the cheesy Reverb-unit and get a 2nd Master Volume instead...
Attachments
01 - plexi channels mixed strat breakup.mp3
(609.95 KiB) Downloaded 1018 times
02 - plexi normal channel LPjr .mp3
(315.35 KiB) Downloaded 905 times
03 - plexi high treble channel LPjr.mp3
(349.44 KiB) Downloaded 993 times
04 - 2204 treble channel LPjr.mp3
(503.85 KiB) Downloaded 965 times

Colex
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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by Colex » Sun Sep 05, 2010 8:56 am

Awesome sounding! :D

Congratz on the work. Through which cab is it played on the clips?

twango
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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by twango » Thu Sep 16, 2010 1:38 pm

It´s my Marshall 1960A Chequerboard RI from the mid 90ies 4x12 G12M25.

By the way... I took the PPIMV out and put in a MV right at the treble wiper (as usual on 2203/04). Sounds very much better than the original MV. You can see the twisted wires on the pix. There´s a hum-loop between the MV and the following FX-card when the MV is all the way down and the FX loop is switched active, so I had to put the MV with a 470R resistor off ground.

Lately I ripped the reverb... sounded cheesy. I never understand what one does with a reverb knob in a higain amp... camouflaging bad playing??? :mrgreen:

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antosimoni
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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by antosimoni » Fri Oct 22, 2010 4:18 am

awesome!!
I awlays wondered howe to put my hand sin this computer-like amps, once I got to change a resistor in my JVM to be able to switch multiple output tubes but it got me a lifetime to change it, Im astonished on how easily you did those jobs on a VM, my congrats :rock:
in loudspeakers we trust

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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by twango » Wed Oct 27, 2010 3:16 pm

The VM is very service-friendly. The complete preamp/PI board is just held by 2 screws and the pots.You just have to turn the chassis, pull the ECC83, unscrew the pots, you can unclip some connecting wires and get the whole stuff out onto the bench in 5 minutes... I was very surprised how easy it was to mod it!

Maybe Marshall should have marketed the VM as the "Plexi-AFD", would have been a great seller :mrgreen:

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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by HF1600ie » Sun Oct 31, 2010 11:35 am

Hi Twango,

I am having a lot of fun with my VM for about 1 year already.
But the Body control is way too bassy and I wonder if it´s boosting the righr frequencies.
Is this mod you have made to your "normal channel" going to fix it ?

With all the on the "normal channel" and "treble channel" will it be very close to a JTM45 in the Low dynamic range?

For me, the Detail knob is OK. The "mid-boost" is ok too. Just too bad the LDR doesn´t have a little more gain on its own, turning into overdrive more easilywhen the detail is above position 7 or so. My pickups are low in output.

PS - Does the circuit self-discharge when it´s OFF ? Do I have to check for current in the capacitors? I usually do nevertheless.

Cheers ! Your amp sounds great. :-)

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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by HF1600ie » Sun Oct 31, 2010 1:25 pm

Hi again, I Was looking at your "normal channel" mod.
IF you remove R9 and replace R8 with a new resistor, jumpering it to R9´s end , then... the "mid boost" section will be isolated from that part of the cirtuit ? ( i mean R88, C6 and C7 ) will be out from VR1 and V2. Am I right ?
Will it still be a mid boost ?

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FortinAmps
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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by FortinAmps » Wed Nov 10, 2010 11:17 am

@ twango, very cool man :rock: I like the VMs for modding as well. Great amp and you can scoop them up cheap on ebay.

First post on Metro, hello to everyone. Lots of great stuff here!
Cheers,
Mike

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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by jerrydyer » Wed Nov 10, 2010 4:14 pm

Whats up Mr. Fortin :rock:
vids.
http://www.youtube.com/user/jerrydyer?feature=mhw4" onclick="window.open(this.href);return false;
http://www.dui-specialist.com" onclick="window.open(this.href);return false;

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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by HF1600ie » Thu Nov 11, 2010 5:53 am

Hi,
Getting back to these mods...
I´d like to shape the mid boost to something that boosts more overall gain than actually "low-mids". Or maybe use it as a treble/gain booster? What can we do, and how can we do it ? How does the mid-boost switch actually works? I think R88 and C6 are related to it, but not sure how it works.

It would be interesting too to "tame" the Body control a little bit, making it more usefull from 0 to 10. More gain, and a little less bass ? I find it useless from past 12 o´clock.

I think twango is away for quite a while. He doesn´t come to the forum very often, but his amp sounds great and would be good to share a few ideas !! What do you guys think or have performed to your VM so far? :thumbsup:

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Re: Vintage Modern 2266 conversion to 1987/2204 specs

Post by FortinAmps » Thu Nov 11, 2010 9:20 am

twango wrote:The VM is very service-friendly. The complete preamp/PI board is just held by 2 screws and the pots.You just have to turn the chassis, pull the ECC83, unscrew the pots, you can unclip some connecting wires and get the whole stuff out onto the bench in 5 minutes... I was very surprised how easy it was to mod it!
I agree, that's a big plus :rock:
twango wrote: Maybe Marshall should have marketed the VM as the "Plexi-AFD", would have been a great seller :mrgreen:
For the US market now, the VM is special order only. I'm looking forward to demoing an AFD100.
jerrydyer wrote:Whats up Mr. Fortin :rock:
Hey Jerry :toast:
HF1600ie wrote:Hi,
What do you guys think or have performed to your VM so far? :thumbsup:
I've rewired the first two stages, got rid of the PPIMV, revoiced the preamp and power section. I went for a heavier tone. I've got a couple of youtube clips of a VM that I did. Link to it in my siggy.
Cheers,
Mike

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