Improvements for Normal & High Treble channels

Get support and show off your MetroAmp JTM 45 kit builds.

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neikeel
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Re: Improvements for Normal & High Treble channels

Post by neikeel » Mon Sep 14, 2015 8:05 am

koffo wrote:Yes, danman and neikeel,

After applyimg your suggestions is definitely better than before. Today I played around with a Plexitone pedal and added a reverb and a bit of delay, putting all the effects in front of the amp. So I used it 100% clean, attached to the high treble channel volome at 2, raised the volume of the normal channel at 1.5, master volume at 5, basses at 0' mids at 5 and trebles at 4, presence at 6.

Great sound also with pedals now!

Just one last thing: I have a zero-loss effect loop I bought form metroamp site quite a long ago. The question is simple: is it really "zero loss" or I should expect the tone to change after it is installed ?
The first couple that I installed with the switch, next one without (so it was always on) so judge for yourself!
Neil

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Re: Improvements for Normal & High Treble channels

Post by koffo » Mon Sep 14, 2015 2:45 pm

Ok, got it! This is the mission for the next weekend! :D

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Re: Improvements for Normal & High Treble channels

Post by kerveros » Sun Jan 10, 2016 4:59 am

koffo wrote:This morning I tried several things. First of all I swapped the 330uF cap with the 4.7 one... definitely, now the amp sings! :)
The high treble channel now is much more like a Super Lead, brighter and more aggressive. Probably if you play blues most of the times it can be annoying, anyway, in my case, I use to play classic rock and some hard rock sometimes, and for me this has been a major improvement!
Then I added also a 100pF cap on the normal channel and now this one has improved dramatically. With the volume at around 2 it is clean with a good amount of basses but not woofy as it was before. When I raise the volume I get almost the same sound I had before the mods with the high treble channel.

So basically I'm really satisfied, now the amp sounds much more consistent, and most of all I have two different channels with different souls and more versatility.

I noticed also that after the mods, the two channels are much more interactive, if I'm playing on the high treble channel, changing the volume on the normal channel have a dramatic effect on sound (also if the channels are not jumpered!). I noticed it also before modding the amp, but the effect was more subtle. Anyway I don't consider it a defect, on the contrary, I think this is a cool feature of the amp! You can bring brightness to the normal channel, or give body to the high treble one easily now!

I attached some pictures of my amo before the today's mod.

Thanks to everybody for helping me, you guys rock! :rock:

Hi there! I got about the same issues with my JTM45 build (used the metro instructions V2.1) with a PPIMV. I got the 250uf cap.

The problem is that bass is almost unusable. Playing only from 0-2 otherwise it sounds "woofy". Another thing is that a couple of Overdrives and boosters I tried make the amp muddy and fizzy. Other than that the amp is great!

Since you have tried the mod neikeel suggested (4,7uf cap and the volume caps) are you still able to dial tones before the mod? Do you still have that glassy sound on treble channel? Has it become a lot gainier?

I wonder if that mod could be switchable

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Re: Improvements for Normal & High Treble channels

Post by koffo » Wed Jan 27, 2016 4:30 pm

Sorry but I didn't receive the email notification for your post, anyway here is what I found about your questions:
-the High treble chanell lost almost all the glassy sound, but the basic character of this channel is always there, and much more veratile
-the gain: here is the surprise, the gain is slightly lower than before, but then again when used with gain at 10 it si much more usable now, less unpleasant bass frequencies, the sound is more defined

So, just to recap: the sound is a sort of crossover between the original JTM45 and a 1987, it is brighter but not as aggressive as a superlead, it still retains the classic roundness the jtm45 is famous for. The glassy clean sound (with gain at 1 or two) is less present, but the sound I have now when I rolloff the volume of the guitar is simply awesome. In this moment I'm playing with an Ibanez JS, and I can get a wide range of sounds from this combo. With a decent overdrive or booster you can obtain also a nice 80s hair metal style distortion, I wasn't expectin this honestly! Talking about pedals, now this amp takes pedals very well (better than my good old my Fender Tweed Pro, that was my benchmark in terms of pedal platforms).

So again, probably less fidelity to original specs and sound but not so dramatically different, but definitely more versatility. Talking about original specs: this amp IMHO sounds absolutely incredible without PPIMV, adding a master volume has definetely a bigger impact on the sound than the other mods I did.

Hope it helps

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Re: Improvements for Normal & High Treble channels

Post by Roe » Thu Jan 28, 2016 2:23 am

On the normal channel I prefer a bright sounding jensen pio 5nf coupling cap and a ceramic 220pf bright cap. On the bright channel I prefer a 3.3nf-3.9nf mustard and switchable 1000pf/5nf bright caps. Mixer is 270Ks with 500pf bright cap and cathode is standard jtm with a NOS 16V cap
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Doug H
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Re: Improvements for Normal & High Treble channels

Post by Doug H » Thu Jan 28, 2016 3:22 pm

A switch to lift the bright cap on the mixer network is a very versatile mod.

You get a normal channel that isn't that dark and takes pedals great and a bright channel that is a little more laid back but still snarls at half gain due to the bright cap across the volume.

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Re: Improvements for Normal & High Treble channels

Post by kerveros » Sun Jan 31, 2016 2:19 pm

koffo wrote:Sorry but I didn't receive the email notification for your post, anyway here is what I found about your questions:
-the High treble chanell lost almost all the glassy sound, but the basic character of this channel is always there, and much more veratile
-the gain: here is the surprise, the gain is slightly lower than before, but then again when used with gain at 10 it si much more usable now, less unpleasant bass frequencies, the sound is more defined

So, just to recap: the sound is a sort of crossover between the original JTM45 and a 1987, it is brighter but not as aggressive as a superlead, it still retains the classic roundness the jtm45 is famous for. The glassy clean sound (with gain at 1 or two) is less present, but the sound I have now when I rolloff the volume of the guitar is simply awesome. In this moment I'm playing with an Ibanez JS, and I can get a wide range of sounds from this combo. With a decent overdrive or booster you can obtain also a nice 80s hair metal style distortion, I wasn't expectin this honestly! Talking about pedals, now this amp takes pedals very well (better than my good old my Fender Tweed Pro, that was my benchmark in terms of pedal platforms).

So again, probably less fidelity to original specs and sound but not so dramatically different, but definitely more versatility. Talking about original specs: this amp IMHO sounds absolutely incredible without PPIMV, adding a master volume has definetely a bigger impact on the sound than the other mods I did.

Hope it helps

Strange, I also didn't get a notification email on your reply.

Well anyways, I tried the mod myself and I tottaly agree with you!
A few days later I went back for the original spec cause I dig that glassy sound.
It is a matter of taste after all! ;)

My notes: that glassy sound was gone and YES the gain was also slightly lower! The bass was more controlable and my OD pedals sounded way better.


Pedals used: Fulltone OCD, Keeley Katana, Jam Pedals Tubedreamer 72, Klon (clone-refractor), Fuzz Factory (clone). All sounded descent with the MOD. Now that I went back to "stock" I use only the OCD and have to tweak it to my liking (that HPF/ LPF switch of the OCD helps as well).

I have the PPIMV (PEC potentiometer George M. demonstrates https://www.youtube.com/watch?v=vypgBhGQwJA)
and kind of trouble me that everyone says it has a great impact on the sound of the amp.
I wouldn't be able to use it without it anyways. It's really loud.

Thanks for your reply!

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