Mojotone JTM45 Schematic in Emailable Form?

[smokin' tone]

@ Jelle. I didn't know the Mojo tranny had different taps. The one I worked on for a guy was 3.4k only. It had to be at least 3-4 years old.

[Zippy]

Merc,
Just thought I'd share a Champ(ish) Circuit with you....

Here's one example of what goes into a Champ-style build:

http://www.youtube.com/watch?v=9ByYWlV7 ... re=related

[jelle]

@ Jelle. I didn't know the Mojo tranny had different taps. The one I worked on for a guy was 3.4k only. It had to be at least 3-4 years old.

You cannot do a JTM45 with a 3.4K primary. Not with KT66's at full tilt.... smoke is the result.

Jelle

[steven21042]

I think I've decided to build this thing according to Guttermouth's build tutorial. I really have no other option other than having someone do it for me. After much..& I DO mean MUCH deliberation and all the splendid advice from THIS FORUM I feel a lot better mentally to approach this thing. I watched his tutorial for what seemed like the 60th time and I actually felt comfortable with the thought of trying to mimmick his assembly. The pics are there in nice detail and the parts are identical (as far as I can tell) to my parts. I'm hoping that I can start this thing with the hope of LEANING ON YOU GUYS and PICKING as MUCH BRAIN MATTER as I can when I fall into the abyss of my ignorance. I still don't know how all certain stuff affects the other stuff in the chassis or even how the AC from the wall socket travels through all the wires and components and ends up as sound. I'm actually considering doing a Tweed Champ box like Merc suggested for $600 as soon as I get finished with this THING somewhere around 2014.

[smokin' tone]

@ Jelle. I didn't know the Mojo tranny had different taps. The one I worked on for a guy was 3.4k only. It had to be at least 3-4 years old.

You cannot do a JTM45 with a 3.4K primary. Not with KT66's at full tilt.... smoke is the result.

Jelle

Yes I know that. I was saying the Mojo kit that I saw only had the 3.4k tranny. It did not have the extra tap on the secondary. I just went back and looked at the pdf you posted. I see what you are saying now.

[steven21042]

I just broke off a pin to one of my preamp sockets. No doubt from the de-soldering I put it through. I wanna go to Tube Depot for a replacement since they have a STELLAR past with me. Any suggestions? I want to go ahead and replace All the preamp sockets with new. I'm thinkin that the power tube sockets have stood my heat.

[The New Steve H]

I don't know what happened, but heavy wire can stress the pins when you fiddle with it. I finally ordered some 22 gauge from Apex. Can drop some off if it ever gets here.

[steven21042]

http://www.tubedepot.com/sk-9ping.html

[Structo]

I know this project is way past this but when I make a eyelet or turret board,
I make a 1:1 layout of the board.

Then I tape that to the board.

Take it to my drill press and drill where the holes go. Works great and eliminates a few steps.

[The New Steve H]

Steven got this thing running, and he has been emailing me his opinions of the amp. It sounds like he will need some tips to tweak it and make it his own. I suggested trying a 12AY7 in the preamp. Hoping he will come back and get some input.

Thanks for all the help.

[jelle]

Great to hear!

[marcoloco961]

Steven got this thing running, and he has been emailing me his opinions of the amp. It sounds like he will need some tips to tweak it and make it his own. I suggested trying a 12AY7 in the preamp. Hoping he will come back and get some input.

Thanks for all the help.

Great news. Getting the amp put together and having it just work gives a big confidence boost to the new builder.

Now, you begin the journey to tweak it to personal taste and in the process, you learn more about how the circuit functions. Tweaking can't be tough, my personal experience is to only do one tweak at a time, then play it for a decent period of time to assess the result and if you like the new tone better or not. If not, reverse that tweak before making another. This way you get the feel better for what each change does.

I think I would start with Steve H's suggestion of trying a few different tubes in the various positions. Sometimes a different brand or model of tube will give you what you are looking for without having to re-wire anything. If that does not get you there you could start with some simple Cathode bypass cap tweaks, or a tone stack cap, or coupling cap tweak. Just remember that some adjustments like raising or lowering a plate voltage or changing of the plate resistor value might require a change of the cathode resistor value to keep bias in the proper range.

Before you start to tweak search for Martin Manning's load line plotter and the tone stack calculator at Duncan Amps website. Figure the programs out and plug in different values and watch the results. This will give you a better idea of how the changes work on the circuit.

[steven21042]

come on guys...I thought that I had finished my penance. I have to say however that I do feel a little proud of myself. Getting a kit that I knew nothing about. Trying to figure out what kind of amp it was. Trying to follow tutorials when I didn't know the difference between an ohm and an amp . And those DAMN HEATER WIRES! ...Then having to replace numerous tube sockets and desolder then resolder because I did it the jackass way. Then firing it up and hearing my tranny making horrible noises and subsequently finding and fixing the problem on my own. All the headaches, all the reading and ALL the research work. The whole thing almost did this OLD MAN in. If it hadn't of been for this Steve H guy in here egging me on and giving me assurances I would have shoved the damn thing in the back of the closet and forgotten about it long ago and just charged a Marshall. So now, you guys tell me that this is JUST the BEGINNING? There's more aggravation ahead? More temper tantrums and loud profanity? .....Kewl.

Thanks Steve and all of you guys that helped me out!

[The New Steve H]

Ohms are the same thing as amps.

No, really.

[marcoloco961]

Oh Steven, if you only knew the depth of the decision you made to start building amps, and the addiction that will soon follow. LOL.

You will tweak, find a tone you like and say, wow, I am done. Then in a short period of time you will find yourself in front of the open amp chassis with a soldering iron in hand saying, well just one more little mod.............................................................................................

Good job my friend, welcome to our nightmare.