JTM45 Impedance

[Littlewyan]

You're right a lot is done in the studio. Another good example I can think of is Randy Rhoads. He used to record each song 2/3 times which is why his tone sounds so fat. Altho I think on one of the two albums he did there is one song where he didn't do this and you can hear the difference. Might be getting mixed up but I'm sure I heard this somewhere.

[wyatt]

Hmm...I always thought Angus used a Super Lead Plexi, and that Malcolm (from time to time) would use the 45...

The "company line" is ...

...Malcolm used a JMP Superbass/1992 exclusively for decades and added a JTM45/100 starting with Ballbreaker.

...Angus used mostly JMP's (1987's so they could be cranked) and then famously used a JTM-45 for Ballbreaker.

But there is plenty of evidence that they have both used a mix of equipment over the decades, including preamps (Mesa and JMP-1) straight to PA for some tours.

Heck, considering the live tones both Angus and Billy Gibbons have gotten out of JMP-1 preamps, I surprised they aren't more in demand.

[matt h]

(deleted)

[Littlewyan]

I've heard something similar to that. I did wonder about Angus how he manages to cut through the mix with his solos as you don't see him use a footswitch to change amps and I don't think he turns down his guitar volume for rhythm. Wonder if his roadie switches the amps for him, I know some guitarists have their roadies turn on effects for them. Just lazy really . I think I'd much rather have control of my rig rather than have my roadie do it for me.

[wyatt]

Well, that's showmanship.

The big touring shows are all spectacle. People want to see Angus and Keef and others strutting around the stage putting on a show and not tethered to a pedal-board.

They have reliable pros that make sure the show sounds exactly the same every night, regardless of venue. Everything is choreographed, even the runtimes are nearly identical between every show. The real amps are isolated deep off-stage so they can be mic'ed, mixed, and maintained almost like a running engine.

It helps when you have a charismatic player that will strut about the stage, get the most range out of a wireless system, and work the audience into a frenzy. "Misdirection"...just like any great stage or magic show, the trick is to keep the audience distracted from noticing the routine. That frenzy is why, despite an act playing the exact same show night after night, you just had to be there to get the full experience.

[Reeltarded]

http://www.solodallas.com/recording-bac ... ony-platt/

Recorded at my pal's place.

[pdf64]

the optimal match for output in a Class AB, push-pull is (IIRC) 4k per the tube data sheet

What data sheet are you using, I can't see how you get that?
Well, I can but a 4k load seems to result in excessive plate dissipation http://bmamps.com/Tech_tds.html

[Roe]

On the Black Ice Album. Then again thinking about it that sounds like he has a big bright cap and has the volume down low. There has always been question marks when it comes to what amps ACDC use. In interviews they said they never used Master Volume amps, however in the early days thats what they had on stage!

thats mostly wizard amps. but ballbreaker is reported to have been three jtm45. the subsequent tour showed a jtm50 however

[Roe]

Hmm...I always thought Angus used a Super Lead Plexi, and that Malcolm (from time to time) would use the 45...

I think I remember reading an interview with Angus, must've been late 90s? early 2000s? Anyway, I believe he said his typical setup (at least live?) was a 100w *and* a 50W. The 50W got more of the leads (pushed harder, more sag and compression). I think, by extension, the JTM45 took on the 50watters duties when it was used for that purpose. It wouldn't surprise me if Malcolm was using the JTM45 more consistently elsewhere, but I definitely remember latching on to Angus talking about the two wattage amps and how it was contrary to what the interviewer assumed (more for leads? nope. more saturation and sag for leads!) I may well be wrong about this, but doubt I hallucinated it entirely. I'm not an AC/DC expert and it was before I became obsessive about guitar amps. [/list]

mal would often, not always, use jtm45/100 and superbass

[Roe]

I've heard something similar to that. I did wonder about Angus how he manages to cut through the mix with his solos as you don't see him use a footswitch to change amps and I don't think he turns down his guitar volume for rhythm. Wonder if his roadie switches the amps for him, I know some guitarists have their roadies turn on effects for them. Just lazy really . I think I'd much rather have control of my rig rather than have my roadie do it for me.

the panning changes from right to center during solos. and he often turn up the volume of his guitar in addition

[Roe]

Hmm...I always thought Angus used a Super Lead Plexi, and that Malcolm (from time to time) would use the 45...

The "party line" is ...

...Malcolm used a JMP Superbass/1992 exclusively for decades and added a JTM45/100 starting with Ballbreaker.

...Angus used mostly JMP's (1987's so they could be cranked) and then famously used a JTM-45 for Ballbreaker.

But there is plenty of evidence that they have both used a mix of equipment over the decades, including preamps (Mesa and JMP-1) straight to PA for some tours.

Heck, considering the live tones both Angus and Billy Gibbons have gotten out of JMP-1 preamps, I surprised they aren't more in demand.

nice summary. The 1987s appears to have been used only for solos and licks in the studio. and there is little sign of jmp1s

[Roe]

On the Black Ice Album. Then again thinking about it that sounds like he has a big bright cap and has the volume down low. There has always been question marks when it comes to what amps ACDC use. In interviews they said they never used Master Volume amps, however in the early days thats what they had on stage!

yes you see a lot of 2203s in 1977-79. but some of these amps are the early 1976-77 models which had only 2 gainstages (+cathode follower). These amps are more similar to a 1959 than the later 2203s

[billyoung]

the blues breaker amp on john mayall recording, i assume this amp was 6.6 k
with kt66s .....its legendary so is a jtm50 black flag with tube rectifier. Two different animals in the amp kingdom. I think its harder to wring the tone out of the model 1962 bluesbreakers as opposed to the black flag. You need to
have some power in your hands i think with cetain amps to get the sound, or the harmonics of mr gibbons. Supposedly tuned a les paul to A for track rythemean noone could get a god chord on it was so loose, but listen to track.
thats also ("i was told") part jmp1 preamp jacked int the board and part real marshall mixed , not the old fashined garage days methods, as was said in magazines. they use same combo love now i believe.


bill

"i was born ignorant , and been goin downhill ever since"

[billyoung]

using 6600

then connect 8 ohms to the 16 ohm tap

should load it twice as hard the normal is 3400 i believe.

think the filament draw on EL34 s is stiff tho , need to have PT

will handle the filaments.

[billyoung]

heres differences i found

"Hi all,

I'd like to try KT66 in my Rocker 30.
But EL34 and KT66 have not the same spec :

EL34 (JJ)
Filament Current 1.5A
Plate Voltage (max) 800 V
Plate Dissipation (max) 25 W
Screen Voltage (max) 800 V
Screen Dissipation (max) 8 W

KT66
Filament Current 1.3A
Plate Voltage (max) 550 V
Plate Dissipation (max) 25 W
Screen Voltage (max) 550 V
Screen Dissipation (max) 3.5 W"

thought filament draw was more than this difference.f

.2 amp per tube so for 2 need .4 more

difference in max plate B+ is like 250 volts LOL

lot did mod to el34s back in day and
i am sure fried some amps.

seeing how this is not a $10,000 "vintage" situation.
can be more rad with it