6JM6 Infomation for Pete Millett's DCPP Amp

[Dagwood]

Hi all

I'm putting together a parts list for this amp and have a few questions,

I'm planning on using 6JM6 or 6GV5 as I like the plate cap look, my question is what size top cap do I need as the datasheet only shows it as a C1-3 cap dose anyone know what size this is? http://www.mif.pg.gda.pl/homepages/frank/sheets/123/6/6JM6.pdf

Also, what cable would best suit to connect the cap and plate connection on the PCB, plate voltage will be about 325V ( not sure of current? ) so was thinking that a silicone - flexible - stranded cable?? any tips would be great

Cheers

 

[neonthecat]

For my DCPP I used caps from Pacific TV: Pacific T.V. - Vacuum Tube Sockets.
Silicone rubber H.V. test lead cable (1000v rated) was what I used for the leads.

 

[rknize]

I only have one size kicking around. It's the type that fits the 807. They are usually referred to as "small".

 

[Dagwood]

Thanks guys

I found this one at RS is high temp as well,
RS | Cables | Equipment Wire/Instrumentation | High Temperature Wire | High Temperature

I'm sure 3A is high enough for this one.

Iv'e also checked out Pacific TV, thanks for the heads up neonthecat

Cheers

 

[neonthecat]

Here's a close-up image of the 6JM6, cap and lead on my DCPP.

(BTW...you are really going to love the music this design reproduces. DIY'ers are very lucky Pete made this so easy for us to build with the quality PCB he offers.)

 

[Dagwood]

Nice work, that is exactly the look I want.

Yes really looking forward to starting this one! I have shelved 2 other amp projects to work on this one, biggest nightmare is having to wait! as we are shifting from the UK to New Zealand in a few weeks so spending the time trying to source parts ( real trouble with the Ixys IXCP10M45S) for this one and dreaming of my new workshop!

Did you try the 6JN6's as well?

Cheers

 

[Perseo]

I am building a DCPP, and have collected some eligible sweep tubes.

Yesterday I was looking at my 6GV5s. They do indeed have a physically "small" grid cap. I have some small ones that I use on 6C8G and 6F8G. These fit perfectly. This size cap is listed as a "skirted miniature."

Above someone refers to the "small" grid caps as being those that fit the 807. I don't have an 807 on hand. but I think that is not correct. Look at this web page, which refers to the 807 size grid cap as a "medium."

Tube Sockets & Grid Cap List @ ABC Vacuum Tubes

I just looked at the charts for some of these tubes. Although the cap for an 807 is indeed referred to as a "small," the cap for 6GV5 and 6JM6 (and 6F8g) is the "skirted miniature", and I can assure you it is smaller than small.

 

[neonthecat]

....snip...
Did you try the 6JN6's as well?

While I do have a couple of quads of 6JN6's, I have far more of the "M's" so that's what I used. It won't matter, sonically, as the electrical specs are identical. Just be sure to pay attention to the changes in resistor spots on the PCB for 6JM6 vs. 6JN6.

 

[rotaspec]

Nice work, that is exactly the look I want.

Yes really looking forward to starting this one! I have shelved 2 other amp projects to work on this one, biggest nightmare is having to wait! as we are shifting from the UK to New Zealand in a few weeks so spending the time trying to source parts ( real trouble with the Ixys IXCP10M45S) for this one and dreaming of my new workshop!

Did you try the 6JN6's as well?

Cheers

PM me when you get settled in NZ. I have a few of the 10M45S if you still need them then.

Gary

 

[rotaspec]

I am building a DCPP, and have collected some eligible sweep tubes.

Yesterday I was looking at my 6GV5s. They do indeed have a physically "small" grid cap. I have some small ones that I use on 6C8G and 6F8G. These fit perfectly. This size cap is listed as a "skirted miniature."

Above someone refers to the "small" grid caps as being those that fit the 807. I don't have an 807 on hand. but I think that is not correct. Look at this web page, which refers to the 807 size grid cap as a "medium."

A 6mm (1/4 inch) cap fits the 6C8G and a 10mm (3/8") cap fits the 807

Gary

 

[Dagwood]

Hi Neonthecat, Perseo and Rotaspec

Neon, is your heatsink from a computer PSU? nice job on the case work.

Thanks for the advise on top caps, I was working my way through the lists on the Pacific TV website and then trying to compair against the datasheet for that valve!!!
So thanks all for the advice.

And thanks Gary for the offer, I will def PM once settled these are like hens teeth!!
Cheers
Ben

 

[neonthecat]

....snip....

Neon, is your heatsink from a computer PSU?

Ben,
Yep. I had it left over from a computer upgrade project. The SS bits are mounted to the heat sink bottom with small machine screws into drilled and tapped holes. The sink is then bolted to the (anodized aluminum) chassis top plate. With the sink and the top plate, there is more than ample heat dissipation.

 

[Dagwood]

Design wise this is my biggest problem, the heatsink??? even thinking fan cooling???

I will try to keep the chassis frame height the same as my 6N1P Headphone amp ( hope the pic attaches ) but really am stuck in my head as the size, shape and style of the heatsink!!

But that's why we do it I guess

 

[neonthecat]

Pete mentions on his DCPP webpage, that he added the heatsink after he found the top-plate was hotter that he expected.

When I build my version, I found many heatsinks available on ebay, but used the CPU heatsink I had on hand. The top-plate I used is a bit thicker that the one Pete spec'd, so is also soaking up heat.

You mention fan cooling....
It can't be seen from my posted image, by there is a very small DC fan mounted in the bottom plate. It blows upward directly on the PCB. It is quite silent and provides some air circulation to the components on the board. You probably don't need a fan on this modest little amp, but it can't hurt and was easy to install.

 

[Dagwood]

I plan to use a 3mm top plate as with the amp above, like you say soaks up the heat.

The only heatsink in my stock would be overkill for this project so will keep looking

Did you run your fan off the heater supplies? and is it switched? manually or thermo switch?

 

[neonthecat]

....
Did you run your fan off the heater supplies? and is it switched? manually or thermo switch?

Just tapped into the heater feed with the addition of a small SS rectifier bridge. At around 6 volts, it's running at about 1/2 speed and is quiet. The fan is always on when the amp is switched on. Simple.

 

[pmillett]

Top caps...

Sweep tubes do indeed use "miniature" caps, and the 807-size cap is called "small".

Drawings are here:

http://www.tubebooks.org/tubedata/HB-3/General/Bases_Top_Caps-7_Pins.pdf

"Large" is actually 0.800" (20.3mm)!

Pete

 

[Tubelab_com]

Sweep tubes do indeed use "miniature" caps, and the 807-size cap is called "small".

I have probably stuffed more different tubes in Petes board than Pete has. There are plenty of different tubes that will work in the board with no (or minimal) modifications. Two different size plate caps are needed. The 6JM6 and many others have a 1/4 inch cap which is called "skirted miniature". Some other tubes that will work in the amp without modification like the 6LR6 use a 3/8 inch cap that is called "small". This is the same size cap that is used on the 807.

There are dozens of other tubes that can be made to work in the big red board if you are willing to modify things. Some modifications are simple, some not so simple. All of these tubes will use one of the same two plate caps. Right now my board contains E130L output tubes. This required rigging some octal sockets into the board.

 

[Dagwood]

Thanks Guys

I read through the entire thread last weekend, made a few notes but didn't see any detail on the caps so thanks. That datasheet is exactly what I was looking for and is now printed and in the project file.

Tubelab.com, I think I will stick with the 6JM6 set I've just won on ebay, look like a nice set and the guy is sending them straight to NZ for my arrival! I may try a few further down the road but as most stock is in the USA the shipping price is always an issue. You seem to have extracted the absolute limit from this design and always a very interesting read. Did you ever put yours in a case?

Cheers

 

[Dagwood]

Just tapped into the heater feed with the addition of a small SS rectifier bridge. At around 6 volts, it's running at about 1/2 speed and is quiet. The fan is always on when the amp is switched on. Simple.

__________________

Hi Neonthecat

Simple sounds good to me, think I have a 40mm dc fan in my stash.