LarMar MV JTM45

[dcburn mk.ii]

I want to try out a LarMar MV in my Metro kit JTM45. Looking at “how to’s” and more specifically where to hook up to power tube socket, I already have a wire with two resistors installed in those positions. Do I just add the mod wires there and leave the resistors as well? I don’t see these resistors on the Metro build sheets?

 

[dcburn mk.ii]

Dave Friedman answered my question.
I’m all set.

 

[chumbucket]

Dave Friedman answered my question.
I’m all set.

Please enlighten us too.

 

[dcburn mk.ii]

Please enlighten us too.

First and foremost I am not an amp builder.
These resistors weren’t in my build sheets (I gave a guy $500 for the head) Dave informed me that they were grid resistors. And to still go ahead and add my LarMar wiring there.

I asked if he thought I could get away with putting the MV in the lower normal channel input rather than the backside speaker input without creating noise.
He said maybe… haha

 

[dcburn mk.ii]

 

[dcburn mk.ii]

Working on the install now. Reluctantly installed in rear speaker jack just because I am a novice and want the lowest possible chance of noise. Next soldering to grid resistors.

 

[dcburn mk.ii]

Added some shrink tubing for the wires to grid resistors. Had to strip a bit of shielding off to make the stretch between.

 

[dcburn mk.ii]

 

[dcburn mk.ii]

I guess it’s time to double check my work and plug it in! Oh brother…

 

[dcburn mk.ii]

Works great!

 

[harddriver]

Congrats! Did you disconnect the green and orange PI output grid wires from under neath the circuit board? I see them still connected at the input grid of the power tubes on what I think looks like two 5.6K(GREEN/BLUE/RED) put in parallel. Is that what they are it's a little hard to make out the colors perfectly from the pics? If it works without squealing then you got the phases from the PI hooked up correctly on the power tube lugs, if they are reversed you will get squealing. Most usually disconnect the original green and orange input grid wires from the PI.

Normally it's just one 5.6K there I don't why the previous builder did that???

 

[dcburn mk.ii]

No squeeling at all. Gotta admit I was nervous too, I’ve read so many negative things in forums on adding the MV, but really works well. Friedman did the MV, loop and gain stages in the 18 watt I built and his MV works fantastic too.
Really thinking I may sell off my Fryette PS2 and put it towards other gear.

 

[dcburn mk.ii]

I do kinda wish I had the guts to have tried it in the front panel though. A bit more handy.

 

[skoora]

No squeeling at all. Gotta admit I was nervous too, I’ve read so many negative things in forums on adding the MV, but really works well. Friedman did the MV, loop and gain stages in the 18 watt I built and his MV works fantastic too.
Really thinking I may sell off my Fryette PS2 and put it towards other gear.

But the Fryette gives you a loop for your JTM45

 

[dcburn mk.ii]

But the Fryette gives you a loop for your JTM45

It does. That was one reason I purchased it, but more so for using it as a MV.
But I dont use much more that an OD, reverb and delay.

I’m still thinking of rehousing the amp into the larger chassis. It is in the larger headshell. The builder crammed it into the small chassis like my 18 watt. It fits, but there’s barely room to stick a finger in there. Then I’d have the room to install the loop I had previously purchased.

I have an IR-J that I use with my iPad and interface. I tried it thru the PS2 and didn’t like that at all.