Metropoulos Forum

It's kind of quiet in this area, so I thought I'd try to start something...

I'm just getting started with a new 50-watt project. With George's kits gone, now, I've had to source parts from various suppliers, but it is kind of fun to go "shopping." I've got all of the parts, now, save for a few small caps, so I've started bolting a few things together. I'll get some pics up soon.

Here is my parts list:

Chassis & Faceplates -- Ceriatone. Chassis is riveted in the corners, rather than welded. It has a few extra holes in it. It has a spot for the voltage selector, so that's going in. Faceplates, of course, have "JMP" on the front, which is a nice touch.

Head box -- Mojo.

PT and OT -- Chris ******. I've heard good things about his iron and thought I'd give it a try. A bit more expensive than Marstran, but Brian was out of stock. PT comes with mounting plate, which, again, is a nice touch.

Choke -- Classic Tone. Good price and quick shipping. Again, Marstran was out of stock.

Board -- Brian H. Nice-looking board, fully perforated.

Mustard caps -- bought from a member here in the classifieds.

Misc. caps -- picked up some Lemco micas and a NOS ceramic 5600pf (bright cap; I may give that value a shot) on eBay.

Using F&T cap cans. I picked those up, as well as the tube sockets, switches, etc., from AES.

I had a bunch of resistors (CC and CF), but picked up what I needed, from Mouser, along with some BC components e-caps and whatever I didn't get from AES.

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Now, a question... I picked up a bridge rectifer like George used in his kits. All of the pics I've seen of JMPs that used this type of rectifier, though (rather than the four diodes coming directly off the PT), used an internal cap can mounted like the one in a JTM45, rather than the dual 32-32uf cap on the board. Here's what I'm talking about (pic "borrowed" from Marstran site):



Of course, that can was later moved to the outside of the amp and placed beside of the choke.

My question is this: Is there any good reason not to put the on the inside of the chassis, rather than using the dual cap on the board? Mounting as in the pic would be more "vintage correct," but the other way may work better. I have both caps, and am not really interested in punching a hole to mount it topside...

Opinions are sought...

anyone?

Hi reswot

No problem at all, if you twist wires going to the capacitor mounted inside chassis wall.

I did it in my last project as you can see on following picture. I didn't get noise issue or any other problems whit this.

Daniel

Thanks.

I spent this morning wiring the heaters, indicator, and HT to the rectifier. Seemed like a good place to take a break.

Your welcome. If you need some ideas, you may find it from my last JMP50 project. Unfortunately it is written in German. But the pictures will tell you much more then words. I hope it helps.

Daniel

http://www.lionamp.ch/project_jmp50.php?PicKat=JMP50

Hi, yeah, nice idea.
Keep us posted(with pics please )

Here are a couple of pics...

The inside wiring was a bit neater, but I decided to separate the leads to the voltage selector and impedance selector. They'll be covered up by the board, so it'll be fine!

Finished....

Got everything soldered up and checked the voltages last night. I had to change the bias resistor to 33k, rather than 47k, to have some "play" in the adjustment with these Mullards.

I'd post some pics, but don't feel like resizing them to fit on this board... There's a thread with some pics on the LP forum, if you're interested.

Congratulations on your new amp and well done! I just saw your pictures on LP forum. Nice board also.

Let us now how it sounds.

Daniel