Author Topic: New Power-Scaled Martamp Jtm45 (Read 13125 times)

hamfist · « **on:** November 16, 2007, 04:38:21 PM »

Ok, I've now had a week with the new beast, and had a chance to get to know it a bit.
First -Here's a link to a pic - http://www.box.net/shared/static/tahnglggnd.jpg

It's a fairly standard Jtm45 clone BUT has power-scaling and a pre-PI MV installed.
The cab is a rear-ported 2x12 with G12-65's in it, and was actually constructed at the Matamp factory (as was the head cab), where Martin is apparently going to get all of his speaker cabs made.

So, apart from the EQ controls there are actually 4 controls governing gain/volume at various points in the circuit. So, there's the volume controls for bothe the bright and the normal channels, the PPIMV and the power-scaling control (on the rear). All these are REALLY interactive and there are so many permutations and combinations that one can have. In fact, it took me a good couple of hours of tweaking to start to be able to get my head around the best way to get the tones I wanted.
I have found that as I use more and more power-scaling, I need to reduce the PPIMV. Doing it this way, mimics the tones one gets with the amp cranked.
And. yes, the PS really does enable you to get (as near as dammit) the exact same tones as one gets from the amp fully cranked, but at anywhere down to TV volumes. It's a very impressive bit of technology IMO. martin seems to have done a cracking job at installing it too. It's actually installed inside the head cab, with a computer-type fan running onto to it, to disperse the heat produced. So the PS does exactly what I hoped it would do.
The G12-65's suit the amp very well IMHO. I always like a rich, "fat", not harsh tone, and these give it in spades !

here's a few clips I did. The amp has the channels jumpered, and the volume is at about loud TV-type volume.

heavy chord riffage - http://www.box.net/shared/static/3vn5vl8xoz.mp3

mild crunch chord riffage - http://www.box.net/shared/static/zy8s59gef7.mp3

clean - http://www.box.net/shared/static/rbe9gu61zt.mp3

Personally, for my taste, the amp get's rather loose and saggy in the bass as the gain gets higher. It's not faulty, that's what all Jtm45's do. It's their "sound". I've found the way that I am liking to use it is to have the amp set on clean/slight break-up, and then add pedals for various shades of gain. The cleans are just beautiful and, let me tell you, this thing is awesome with pedals.

Here's a couple of clips (again loud TV volumes) with a Box of Rock runnin through the Jtm. I LOVE this sound !!

BoR heavy chord riffage - http://www.box.net/shared/static/x99xmmnapu.mp3

BoR mild crunch chord riffage - http://www.box.net/shared/static/6vavxu7mc7.mp3

I'd be interested to hear what you think of the clips in comparison to the amp's own tone. I posted the clips elsewhere and many folks preferred the amp's own distortion. For me I like the extra "tightness" I get from the BoR.

And may I say that Martin at Martamp can been an absolute gentleman in all my dealings with him in building this amp. And I was probably slightly more demanding than many folks would have been. Thanks mate !

Crazy_Joe · « **Reply #1 on:** November 16, 2007, 04:44:56 PM »

That sounds awesome, especially the Box of Rock ones!

sgmypod · « **Reply #2 on:** November 16, 2007, 04:45:00 PM »

Nice am seriously wanting him to build me an amp when I have the cash..sorry may be dumb but what's "pre-PI MV" do

indysmith · « **Reply #3 on:** November 16, 2007, 04:46:17 PM »

Gorgeous sounding amp my friend! congrats.
As far as the amp vs. BoR go, i prefer the tone of the amp by itself personally. Yes, it is a lot looser, but to me it just seems more raw and has a three-dimensional quality that the BoR doesn't quite provide. The BoR sounds very nice, and I'd be more inclined to use it for higher-gain, more focussed sounds.

blue · « **Reply #4 on:** November 16, 2007, 04:49:55 PM »

the clean and mildly overdriven amp sounds are fantastic! i agree that the more heavily overdriven sound from the BOR is better. the pedal's milder crunch sound isn't as good as the amp's own, but would be a perfectly good compromise for easier sound changes. if i hadn't heard the amp's own crunch it would be great!

blue · « **Reply #5 on:** November 16, 2007, 04:51:50 PM »

in the picture, i'm guessing the knob on the lower input 2 is for the power scaling?

Will · « **Reply #6 on:** November 16, 2007, 05:13:58 PM »

He said power scaling was on the back, presumably that would be the Pre PI volume?

opprobrium_9 · « **Reply #7 on:** November 16, 2007, 05:31:29 PM »

those cleans are devine, although personally, i would have added a little more bass to it but of course this is just my preference. Nothing, absolutely nothing to complain about.

Gizmo · « **Reply #8 on:** November 16, 2007, 06:24:49 PM »

How much does it cost? Their website doesnt give any prices?

There is no history on their website either. What relationship is Martamp to Matamp?

if you had an amp did they say how much the installation of the powerscaling costs?

martinw · « **Reply #9 on:** November 16, 2007, 08:09:43 PM »

Perhaps I can answer those questions. :)
All the amps I make are different prices, but a typical JTM45 replica or similar would start at about £700. Power Scaling adds £130 to that.
Other amps I do include the single ended EL34 10W Goldstar which starts at £380 for a head and £450 for a 1 x 12 combo.
Power Scaling installation goes from £130-180, depending on complexity.

As to history, I'm an experienced engineer, having started my career on military aircraft, and most recently spent 10 years testing and maintaining machinery in the semiconductor industry. I've always played guitar and currently play in 2 bands.

I have a good commercial relationship with Matamp, which goes both ways, and concentrate on providing services they don't.

Hope this helps.

sgmypod · « **Reply #10 on:** November 16, 2007, 08:52:17 PM »

do you do any other clone amps I.E. fender, mesa etc

hamfist · « **Reply #11 on:** November 16, 2007, 09:21:32 PM »

Quote from: Will

He said power scaling was on the back, presumably that would be the Pre PI volume?

Correct, my friend.

martinw · « **Reply #12 on:** November 16, 2007, 09:26:10 PM »

Quote from: sgmypod

do you do any other clone amps I.E. fender, mesa etc

Basically anything that there are available parts for; Marshall, Fender, Matchless, Trainwreck, even Dumble and some others. More the vintage amps rather than Mesa or Soldano though.

hamfist · « **Reply #13 on:** November 16, 2007, 09:32:14 PM »

Quote from: sgmypod

..sorry may be dumb but what's "pre-PI MV" do

It's simply a master volume which can turn down the signal between the gain stages of the pre-amp (V1 and V2) and the Phase Inverter (PI). Hence its a MV which is pre-PI.
On this particular amp, the power tubes and the PI are all power-scaled. If you apply hefty power scaling, it really helps control the range of nice tones available to be able to control the strength of the pre-amp signal going into the PI and power section. This is exactly what the pre-PIMV will enable you to do.
Therefore you can dial in as much pre-amp breakup from V1 and V2 as you want (using the main bright and normal channel volumes), but then reduce the strength of that signal going into the PI and power tubes, using the pre-PIMV.
It still doesn't act like the traditional "gain" and "master volume" arrangement of a standard modern amp, because NMV amps simply don't produce their distortion that way. NMV amp's distortion is much more shared out between all the pre-amp tubes, the PI and the power tubes.
Trust me, when you're tweaking to try and get great tones at low volumes on this particular amp, it really helps.

I'm sure this explanation seems really quite complicated. It took me a good while to get my head around what it all does.

hamfist · « **Reply #14 on:** November 16, 2007, 09:32:50 PM »

Oh, and thanks for all your kind words about the tones !

Alan