JE Labs - Simple 45

#21
Love it.
I do the same thing and end up moving things around and around, leave it for a day then come back and rethink, many times over often before i make final layout. I try to put function over esthetics but I am very much visual so i drive myself nuts... )
 
#22
The circle connectors are for HT and heaters, I have some 7 pin connectors and could put them all in one umbilical. Perhaps a single umbilical would make it easier to 'tie' the two chassis together for physical earth?

I think I need to sketch this out so I don't lose track.

PSU_CHASSIS:
- B+
- B+ ground/0v
- 6.3v+
- 6.3v ground/0v
- 2.5v+
- 2.5v ground/0v
- physical earth?

Physical earth could also be tied into the braided screen that will be outside the main bundle of wires for the umbilical.

Any thoughts, insights here are greatly appreciated.
You are going to have to dedicate 4 contacts to the 2.5V heaters.
You can certainly earth a shield around the umbilical, but often times the connectors that you're using won't be a great conductor to the chassis themselves.

(Also, I've had lots of those Chinese ceramic wafer sockets fail from broken pin clamps. I would recommend a different socket if you haven't gotten around to drilling)
 
#23
You are going to have to dedicate 4 contacts to the 2.5V heaters.
You can certainly earth a shield around the umbilical, but often times the connectors that you're using won't be a great conductor to the chassis themselves.

(Also, I've had lots of those Chinese ceramic wafer sockets fail from broken pin clamps. I would recommend a different socket if you haven't gotten around to drilling)
The UX4 sockets?
 
#24
You are going to have to dedicate 4 contacts to the 2.5V heaters.
You can certainly earth a shield around the umbilical, but often times the connectors that you're using won't be a great conductor to the chassis themselves.
I was planning on terminating the outer braid shield to a pin so that I could take that to a solid connection inside the chassis. I definitely don't trust the connector to conduct well enough for that.

I guess my question is, is it worth it do screen the umbilical in that manner? It's not much effort, just curious about real world efficacy.

Thank you for your input Paul!
 
#25
The UX4 sockets?
Yeah. On those that I have used, the little black "U" shaped pieces of metal end up snapping in half randomly.
I was planning on terminating the outer braid shield to a pin so that I could take that to a solid connection inside the chassis. I definitely don't trust the connector to conduct well enough for that.

I guess my question is, is it worth it do screen the umbilical in that manner? It's not much effort, just curious about real world efficacy.
I've only done two amps with cabled umbilical cords. I shielded one but didn't shield the other. I don't see any harm in it, but it wouldn't surprise me if your amp was quiet without it (after you get it otherwise sorted).
 
#26
Yeah. On those that I have used, the little black "U" shaped pieces of metal end up snapping in half randomly.
Thank you for the heads up, I'll order some better sockets. My 3/16" aluminum sheet just got delivered, so I've not cut anything as yet.

I've only done two amps with cabled umbilical cords. I shielded one but didn't shield the other. I don't see any harm in it, but it wouldn't surprise me if your amp was quiet without it (after you get it otherwise sorted).
Awesome, I suspected the same. I'll probably just screen it, as I have the materials needed on hand already.
 
#27
Had a bit of time today, and since the metal was here I decided to layout and get to metal work. I went with thicker aluminum this time, 3/16". I didn't try my greenlee punches yet, though I may for the signal chassis.

A quick pic, I'll post some more later as I start slapping pieces onto this chunk of metal.

IMG_1029.jpg
 
#28
I went ahead and got a few components mounted, figured out where the big 50R chassis mount resistor is going, and cut the mounts for the circular connectors. I need to dig up a 7 pin, or order some more.

I was initially planning to mount the filament transformers inside the chassis, but now I'm thinking I may move them up top. Who knows, haha.

IMG_1035.jpg IMG_1036.jpg
 
#32
Got some progress, a couple quick pics, should make some more progress this evening.

So far:

IMG_1037.jpg IMG_1038.jpg

Wiring is likely to get a little tight in the somewhat small chassis, with the filament transformers inside, but I still want to try and keep them inside. We'll see how much it annoys me when I wire it up.
 
#34
A bit more progress between chores etc:

IMG_1039.jpg IMG_1041.jpg IMG_1042.jpg

I'll start on the filament transformers and their wiring this week. Waiting on some 7 pin connectors for their umbilical. Hopefully I can hook up the IEC inlet and test the B+ section. I will likely also order an actual 220k resistor to replace the resistor origami I've got rocking now.

Is the 220k load across the B+ rails enough for me to power up and measure the output? I would think it is, but.... I also think the world is a sphere, so what the hell do I know?
 
#35
Since I'm not using the volume control on the schematic, do I need to place a 100k resistor in it's place? If so, do I put the 6sl7 grid connection in 'front' of the resistor or 'behind' it... ?

Thanks!
 

je2a3

Junior Member
#36
Since I'm not using the volume control on the schematic, do I need to place a 100k resistor in it's place? If so, do I put the 6sl7 grid connection in 'front' of the resistor or 'behind' it... ?

Thanks!
Replace the 100k pot with a 100k 1/2W carbon resistor (or your favorite type). ;)
 
#37
Replace the 100k pot with a 100k 1/2W carbon resistor (or your favorite type). ;)
Thank you sir! I had some Takman REY 1W on hand that I'm going to use.

I got some layout figured out, and in that process figured out that the Russian FT3's I was going to use are just too big to fit comfortably. So.... I ordered some Miflex KPCU, I've heard some great things about these caps, so I thought I would try them. Those should be here in a few days.

In the meantime I'll layout the other bits. I got some teflon sockets in today, so I got those mounted and a few other bits.

Some pics:

IMG_1044.jpg IMG_1047.jpg IMG_1048.jpg

Hopefully some more progress in the next few days.
 
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