Marshall Vintage Modern 2466 power tube question

Rod

Tone is Paramount
Gold Supporting Member
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22,087
I just purchased a 100 watt Marshall Vintage Modern head from a member here, thanks Shawn, and retubed it with some Gold Lion KT66's I had... Man it sounds good but now it's really frickin loud.. Can I pull 2 power tubes and run it as a 50 watter?
Also, does anyone know if I can run 5881 Sovteks in it?
 

Dannyz

Member
Messages
2,189
I just purchased a 100 watt Marshall Vintage Modern head from a member here, thanks Shawn, and retubed it with some Gold Lion KT66's I had... Man it sounds good but now it's really frickin loud.. Can I pull 2 power tubes and run it as a 50 watter?
Also, does anyone know if I can run 5881 Sovteks in it?
Yes you can but its not ideal popping out two power tubes, because you will change the amp´s OT impedance. Here´s some value information


http://musiciansroadhouse.com/viewtopic.php?f=1&t=1867

"I've never tried two EL34s in a 2466, only four so I don't know what it will sound and feel like.

OK, if you are adamant that you want to check out this route you first have to short pins 1 and 8 of the output valves on the PCB with tinned copper wire, otherwise they will be working in tetrode mode. Most output valves have these grids internally shorted but not the EL34!

Next replace the KT66s with the two EL34s (use the inner pair of bases) and switch on. Immediately set the bias to around 35mV per valve (if you have enough range on the bias trimmer) and let the amp come up to temperature. After 10 to 15 minutes check the bias again and adjust if necessary.

That's it, try it and see if you like it.

The HT voltage will be high on the plates of the 34s (maybe around 530 to 545V) but EL34s are actually more robust than you think, especially if you have good ones. The old 'Series 12' as used by EVH had very high HT voltage on the plates also.

The screen grid currents should be within acceptable limits.

The output transformer primary impedance is 4K and 2 EL34s are rated at 3.5K so that is not too far away.

Be aware that by doing this mod you are voiding your warranty.

NOTE: Do not do this with two KT66s as they are less forgiving of higher plate voltages, i.e. do not pull two KT66s out of a 2466 in order to achieve 50 Watts.

Steve Dawson "

If you mod the bias circuit, it can take 5881, they´re good, rugged tubes but less complex and more "2D" in the tone department. I would stick with KT66s. If you want to experiment, the 4K ohm OT can work with a pair of KT88. That way, you will not lose the "big tube" vibe in the amp, i mean, the big headroom factor. 100W vs 50W is only a 3db difference, its all about the headroom, not volume. The amp has a GREAT post phase inverter master volume, the taper is super gradual.

If you want good tone at a manageable volume, you got two options: 1) An attenuator ; 2) Low efficiency speakers (Creambacks, Heritage G12 Greenbacks) or less speakers (goin from a 4x12 to 2x12 or 1x12).

 

michael.e

Silver Supporting Member
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20,530
I have had the 2466. It is not Superlead loud but still...
I now have the 2266 and it is perfect for club gigs. For the price, get the 2266 as well!
EDIT: There is quite a bit of difference in the qualities of the "loud" in both amps. 2266 is much more useable where careful application of volume is needed in controlled environments/clubs.
 
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Rod

Tone is Paramount
Gold Supporting Member
Messages
22,087
Thanks for all that info Dannyz... After reading all that 2x, I think I need to leave it alone and run less efficient speakers. The amp sounds great after retubing it with your suggestions...I've been using an Egnater Tourmaster 2/12 cab with the VM and it's loaded with Celestion lead 80's... It's a huge sound, and for outdoor concerts, I couldn't imagine anything better, but for small clubs (which is what I play mostly on the East coast), I think it may be to loud...Maybe I'll try some Scumback M's, which are higher powered, lower efficiency greenback types... I'd love to try some G12c speakers that the amp was designed for, but I've never even seen one for sale, ever..
 
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Rod

Tone is Paramount
Gold Supporting Member
Messages
22,087
I have had the 2466. It is not Superlead loud but still...
I now have the 2266 and it is perfect for club gigs. For the price, get the 2266 as well!
Maybe I should do that Michael.. Thanks for the suggestion
 

michael.e

Silver Supporting Member
Messages
20,530
Or..
Maybe a volume pedal in the loop and kick the amp up? I have not tried that myself.
 

RussB

low rent hobbyist
Messages
11,170
The amp will be very loud with either 2 or 4 power tubes...IMHO, 4 tubes gives it more punch and balls
 




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