JTM45 tone vs. JTM50 tone

[billstets]

I've been searching the site for info. on the JTM50, but I'm only finding discussions about the components that make up a JTM50. I realize it's a transition amp and the values changed. However, I haven't found anything that describes how it sounds compared with a JTM45.

Can anyone describe how a JTM50 sounds vs. a JTM45, and let's say the JTM50 is basically a JTM45 with the following modifications, which I believe comprise one legitmate flavor of a JTM50 from what I've read:

784-139 OT with EL34s
1K 5W screen resistors
32uf x 32 uf internal can cap
dual 33uf on the board
2x470K resistors instead of 2x270K
tube rectified

Also, as an option to try SS rectification, would a plug-in rectifier be equivalent to a diode rectifier wired into the amp?

[Wayne]

Hi. i have built them both to spec using the correct transformers from Brian Wallace. JJ KT66's in the JTM 45 & JJ EL34's in the JTM 50. JJ's in the preamps of both. Sovtek GZ34's. Carbon comp in all the right places. Same brand pots & caps in both. Bright cap to spec on both.

The 45 has more chime, is brighter with less low end thump & is not as loud.
The 50 has more grind & volume and imo a fantastic low end thump.
They actually sound great together.

One thing i did not like was that i had to have the treble control on the norm channel of the 50 always at max. Didn't seem to have the range of the 45. Anyway i changed the mix resistors down to match the 45 (470k to 270k) and got the range back.

I prefer the 50 (but only just).

They are BOTH better than the 1987 i have built in my opinion. May be due to the tube rectifier or the split cathodes - not sure. I'm sure many will disagree though !!

Wayne

[flip]

Bill this should give you an idea of what a Metro JTM50 sounds like. This is a fellow Metro forum members amp built by Metro forum member Roadrunner. Marstran trannies, all NOS mustards etc etc. This guy in the vid is a longtime friend of mine and I have played this amp many times. We've done may a tastes test with his JTM50 and my Metro JTM45.
Waynes got it pretty much right in his assessment of these two rigs. Check out the vid below and check out all his other vids. I believe he has a few vids of my 45 also.

http://www.youtube.com/watch?v=tdg1VcgxHbc

[billstets]

Thanks guys. That video is cool. Good old Allmans, my favorite!!

I have a Metro JTM45 that I built. It's great, but the distortion when cranked is a little ragged, which I've heard others say as well. I had the crazy idea of converting it to a JTM50, partly because it might sound better (it might not, that's why I ask!) and partly because it would be a fun project. I enjoyed building the JTM45, and I'd really like to build a JMP50, but I really can't afford a full kit right now. Converting the JTM45 would be maybe $200 I figure.

Is the bass response on the JTM50 tighter? I have 10uf V1a cathode cap, so my JTM45 bass is tighter than stock. I also changed the vol pot bright cap to 100pf. I've been thinking of going back to the 500pf again to see how I like it. I've read that the 500pf gives you more gain.

[zrAC/DC]

I'm interested in building a JTM 50, but I love my 45 I built, it has all stock values and after it breaks in good it is just sweet! I don't know what to build first, JMP50, JTM50, or JTM 45/100 (which is what I'm leaning toward). I like the JTM's though!

[Spodeeodee]

Awesome! I didnt realize you (Phil) were on this forum. I love your vids. Dan's too!

Your jtm tones are wicked!

[flip]

Awesome! I didnt realize you (Phil) were on this forum. I love your vids. Dan's too!

Your jtm tones are wicked!

Thanks Spod, yeah I think Dan and I are going to do another taste test with my 45 and his 50, only this time we're gonna run them thru their paces with my 2x12 cab loaded with the "Golds". If you havent seen the taste test with the 45 and 50 thru the G12M 20 watt cab, check out Dan's (skydog46) newest vids on youtube. We just did them the other nite and he posted them Friday morning.

[Spodeeodee]

A taste test with both amps through the Golds would be great to see/hear! Any chance Dan could sneak in the riff from "Lets get it up" that occaisonally finds it's way into his videos?

I've never heard Golds in person, but some of your vids, along with a sound clip George recently posted, have really piqued my interest! Thanks to you (and Dan) for being cool enough to share your time/gear/know-how with the rest of us!

[SammyC450]

Ok guys'n gals,
Let's think about this. Somebody help me with this. This...
I'm in the middle of the 'Black Flag' JTM50 BUILD. You all know it was only around long enough to replace the GZ34 (shame on you for cutting costs, but with the JTM/ JMP conversion... trust me I understand...a lot of us have been there).
If you check out Ceriatone's JTM50 layout (It's ok, nobody's looking), This guy is close!!! He's running arround 420 B+ and no screen R's (just like the originals, but you better have some stout 34's, I beleive he uses JJ). Ok, now you have the basic layout. Unless you have original Mullard el34's, go with the srceen grids, 500 to 1K 5w.
As far as the transformers? Was the PT a Drake 350-350 (420B+ or -). What the hell was the OT, it had to acommodate the el34, was it Hi- Fi? (Drake??)...was the 34 used before this in a guitar amp (not with Marshall)?? I've been talkin' to Paul at Merc and trust me this is very lovely territory.
I'm sorry, this is my first post and I'm rantin'.
BOTTOM LINE:
Don't forget your V1, V2, V3!!! You don't need NOS. Slap a Genelex in V1 ($50) and a couple of Tungsol 803's ($50) in V2 and V3 (with V3 balanced and high gain).
If you have a good layout, all your componants are right... play your amp, the caps will smooth out (SOZOOOO) (30-100 hrs), the tubes will break in and trust me you're gonna be happy, it'll hit you out of the blue and it's GOOD!
Give me some feedback, I hope I havn't offended anyone. I just think sometimes we put the cart before the horse. I love JMP'S but there is just something about that 'SAG', and I've always loved the idea of the JTM50.
Hope to hear from you soon, and I'ved learned much from you all,
SammyC

[arledgsc]

I built both with same PT, Mustards, GZ34, tone stack, NFB, Lar/Mar PPIMV. Larry GND, etc. The JTM50 though has extra filtering on V1/V2, screen resistors different, and of course appropriate Marstran OTs. So for me it pretty much comes down to the output tubes as the major difference sound which have been described above.

Just want to add, as an experiment, I am currently running KT77s in the JTM50 and the sound is very close to KT66s. Big bottom lows, less grind and dirt versus EL34, highs more extended. But the Marshall character and harmonic bloom is there is spades. So for versatility I am liking the JTM50 more and a power tube swap/ rebias lets me easily play in both worlds when it suits me. The JTM45 is my favorite amp of all time though. Scott