JTM100 Live

rgalpin · Post by **rgalpin** » Tue Oct 30, 2007 12:19 pm

this is the closest i've gotten to the sound i'm looking for live - so i thought i'd share it and see what you all think...

board mix -> with a little post production in PT:
http://www.soundclick.com/bands/songInf ... ID=5922992

it's the JTM100 spec with NO attenuator - NO re-amp or slaving.

the JTM100 (vol ch I on 5, delay in a jumper loop) straight into a 4x12 loaded with weber stanspec pre rola treatment speakers.

EVH phase (script setting) and GE10 in front.

6L6 power tubes
heyboer PT
MM OT

i'm thrilled with it - you all like it?

rockstah · Post by **rockstah** » Tue Oct 30, 2007 12:26 pm

sound killer, Rob.

rgalpin · Post by **rgalpin** » Tue Oct 30, 2007 12:28 pm

cool man - thanks! i'm stoked about it.

rockstah · Post by **rockstah** » Tue Oct 30, 2007 12:29 pm

you should be. makes me want a JTM100

rgalpin · Post by **rgalpin** » Tue Oct 30, 2007 1:14 pm

here's another clip that is more rhythm / riff oriented.

http://www.soundclick.com/bands/songInf ... ID=5923136

that good ol' shared cathode is just grindin'.

is it proper terminology to call it a JTM100? did Marshall actually sell a JTM100? my knowledge is fuzzy on this -

what i did to make the amp what I call a JTM100 is i took a super lead 1959 amp and wired the board like a JTM45 with the exception of one resistor that is different because it's 100 watts - something in the rectifier area i think - i call it it a JTM100 but i'm not sure the rest of the world would. would they?

Tone Slinger · Post by **Tone Slinger** » Tue Oct 30, 2007 1:16 pm

Sounds great man ! Whats the specs on a jtm100. Good amount of gain at 5.

rgalpin · Post by **rgalpin** » Tue Oct 30, 2007 3:37 pm

Thanks TS.

i used the values that george indicates on his wiring guide pdf for a JTM45.

820/250 shared
.022 off v1
270k/500p mixer
820 v2a cathode
56/250 tone stack
.1 couplers off v3
27k NFB on 8ohm (not 100% sure on the 8 ohm)
not sure what i have on the presence - might need to check that though - it might be the wrong values for JTM and it does get a little briter than i want it when crank the presence to get it to loosen up.

harddriver · Post by **harddriver** » Tue Oct 30, 2007 8:25 pm

Sounds good Rob. Definitely has a clarity quality going on, especially with the 27K on the NFB, a 47K on 8ohm would give you some more power amp gain and put you into 67 spec territory, I think it would still retain enough clarity.

I've read the 270K mixers will give you some more gain as well that was the original bassman mixer spec. That thing sure grinds nicely.

It definitely isn't as compressed as your 74 plexi attenuated to load.

I guessing your are enjoying the cleaness it's giving you. I hear it to be a little more woody too.

The similarites between a Sylvania 6ca7 and 6L6 is almost too much to discount. I have a an EQ pattern for you to try if you want.

Mantegna · Post by **Mantegna** » Tue Oct 30, 2007 9:38 pm

HEY!!!!!!!!! r u in Funny Money...if you are who I think...Maryland looooves your band.

T.J.Fuller · Post by **T.J.Fuller** » Tue Oct 30, 2007 10:55 pm

That is a great live guitar tone!

Especially, for the style of music you guys play.

Your songs rock by the way,,,,

No 80's "Weasel Tone" to coin a phrase from Yngwie308

Nice thick clear tone....great job

Is HammerJacks still around out there ???

rgalpin · Post by **rgalpin** » Wed Oct 31, 2007 7:39 am

thanks guys.

the NFB and the presence pot and cap values are where i am thinking this amp could use a little tweak. i'm not 100% sure that i have the JTM value pot or cap on there. and the presence introduces a little too much briteness with the added gain between 3 o'clock and maxed out.

the pot value on the presencefor a JTM45 should be what?

hammerjacks is long gone - but we're still carrying the torch through the long dark night...

hey - yeah, in funny money i have to keep those tones in the AC/DC range as far as clarity and ka-chunk goes - being an EVH nut keeps me constantly searching for ways to get enough gain for EVH type expression while keeping the clear clean power chunk in there too. it keeps me from sliding down the slippery slope to 80's weasel tone! most of the time!!

Tone Slinger · Post by **Tone Slinger** » Wed Oct 31, 2007 9:04 am

Ha, Ha, great description/explanation there. I totally understand ya.

rgalpin · Post by **rgalpin** » Wed Oct 31, 2007 10:19 am

don't know if anyone else hears it this way but... the JTM circuit seems to retain its power and punch and sustain at lower settings on the channel volume control.

on the plexi it seems like below 8 it starts to get sluggish and you feel like its fighting you, dragging its feet, becoming lifeless.

but 8 or above on the plexi and you've got a little too much gain and compression to get good clear AC/DC type punch.

cary chilton · Post by **cary chilton** » Wed Oct 31, 2007 4:06 pm

awesome tone as usual Rob!