plexi 67 VS Jtm 45/100

marci84 · Post by **marci84** » Mon Jun 30, 2008 11:51 am

What are the difference between the two beasts? Can i swap from the 67 plexi circuit to the JTM one and viceversa?

Post by **VelvetGeorge** » Mon Jun 30, 2008 7:41 pm

The transformers and power supplies are different. Also the '66 uses KT66's while the '67 uses EL34's.

Most of the circuit values are the same.

You could swap either tube in either amp, but you won't really transform one into the other.

VG

marci84 · Post by **marci84** » Tue Jul 01, 2008 7:05 am

which has more gain between the two? For an ACDC sound from 77 to 80 (from TNT to Back in black for example) which is the best option among JTM45, JTM45/100, plexi 67 and plexi 68?

I don't know really which one to build!!

Roe · Post by **Roe** » Tue Jul 01, 2008 12:14 pm

the latter ones have the most gain and are brighter and more aggressive. I'd recommend a 67 for ac/dc. a 66 will work also, and a 68 will work for ang, but not for mal

marci84 · Post by **marci84** » Tue Jul 01, 2008 12:22 pm

because when i listen to many samples of a '67 plexi a hear a muffled sound..while the jtm100 has a little more raw sound..

for example: Beating around the bush (from Highway to hell CD) has a fantastic tone for my taste! if i'm right it's Angus panned right and Malcolm panned left, the first with a more woody sound and the second with a more "clean" sound (it seems like Angus has kt66 and Mal el34)..i think about G12h30 as speakers, but for that sound it's better the jtm or the plexi 67 or both are good?

and a jtm45 30W? what do you think about it for ACDC?

Roe · Post by **Roe** » Tue Jul 01, 2008 4:15 pm

mal is always on the left and ang on the right. the only notable exception are the solos. mal used mostly a superbass in this period (basically a 1967 with high filtering). ang seems to have used a lot of amps. the preprod recordings of Highway to Hell and beating around the bush [back seat confidential] sounds like the post 68 lead circuit or the earlier circuit with a treble booster IMHO. I guess both used G12Hs or 65watters. I don't think they used kt66s in the old days.

a jtm45 can work but its much easier to get the punchy riffs with the bigger amps

Billy Batz · Post by **Billy Batz** » Tue Jul 01, 2008 4:57 pm

The amp ont he left for some reason I always thought it was a 45 on that song. That was just an impression tho.

Roe · Post by **Roe** » Tue Jul 01, 2008 5:18 pm

Well it aint impossible. mal says he has had one of the earlies 100watters with a white black panel for quite some time. and he said he began using his beloved superbass on dirty deeds. Cf. interviews with guitar player and marshall law

marci84 · Post by **marci84** » Wed Jul 02, 2008 8:03 am

ok now i'm more confused than before

Roe · Post by **Roe** » Wed Jul 02, 2008 8:39 am

well mal is either superbass or 45/100. ang used alot of different marshalls. a 67 may be the best allround angus amp. in any case a 67 can cover both ang and mal. A 66 may do that also but you may need a treble boost to cover some of ang's more aggressive tones (e.g. overdose)

marci84 · Post by **marci84** » Wed Jul 02, 2008 11:59 am

OT: i gave a listen to the cd of the new band Airbourne and i like their tones very much! i don't know if they use marshalls but they have an old ballsy sound with a tad more gain and punch

can someone please post a sample of a plexi 67 that doesn't sound too muddy? like the beating around the bush sound

HEAVIER THAN HELL · Post by **HEAVIER THAN HELL** » Wed Jul 02, 2008 12:38 pm

the only Marshall I've ever had that nailed the Beating Around The Bush tone was a '76 Lead & Bass 2x12 combo with the lower B+ around 350v

the 50w heads around the early/mid 70s had lower B+ and do distort quite early with a really fat, aggressive tone.

marci84 · Post by **marci84** » Wed Jul 02, 2008 1:09 pm

for early 70s marshall you mean non-master volume metal panel (with .0022 coupling cap, bright cap and .022 p.i. outcoupling caps)?

again, if you listen to whole lotta rosie, i hear tha mal on left has a more plexi el34 sound while angus (to my ears) has a more jtm45 sound, that fuzzy sound (i don't find any other word to describe it) is very different to mal sound on the other speaker.

mrkrausman · Post by **mrkrausman** » Thu Jul 03, 2008 12:38 am

i have been searching for this tone everywhere on this forum and have yet to hear a clip anywhere that nails it. It's so damn illusive. Here is a thread from months ago. http://forum.metroamp.com/viewtopic.php?t=16480
I think confusion is a good word to describe it. Their guitars almost have an 'organ' sound.

Roe · Post by **Roe** » Thu Jul 03, 2008 7:15 am

rosie and the rest of the let there be rock album does not sound like a jtm45 unless ang used a booster and a ss rectifier