Jim Kelly Build

[MakerDP]

I'd really like to hear how this turns out. I really like the sound of a Kelly amp and have been fascinated by them ever since reading about them in the TUT series.

I think his current line of amps released through Suhr sound fantastic.

[oj]

Your updated schematic looks great !
The only error I see is that C23 should be 30uF.
See you building A "old" JK, the new ones are similar but no diodes and have a boost funktion.

[dcribbs1412]

Your updated schematic looks great !
The only error I see is that C23 should be 30uF.
See you building A "old" JK, the new ones are similar but no diodes and have a boost funktion.

Would that boost be the mid-boost from the schem on a push/pull Bass pot?
Implementing the presence on the Gain pot is interesting
D

[dorrisant]

Your updated schematic looks great !
The only error I see is that C23 should be 30uF.

Thanks oj... I edited and reposted.

[oj]

Your updated schematic looks great !
The only error I see is that C23 should be 30uF.
See you building A "old" JK, the new ones are similar but no diodes and have a boost funktion.

Would that boost be the mid-boost from the schem on a push/pull Bass pot?
Implementing the presence on the Gain pot is interesting
D

No, is a different boost that Jim had on some of his amps but is standard on the new ones.

The boost is on 3 gain stage a cap on and of over the cathode.

[oj]

Your updated schematic looks great !
The only error I see is that C23 should be 30uF.

Thanks oj... I edited and reposted.

Nice job dorrisant !
You know that is the only complete schematic ever for a Jim kelly
If you like the voltages for the old and new JK, let me know.
Also Jim did increase the screen resistors to 2X4K/10W on his later models.

noticed another error on the schematic.
The diodes D8-9 after the reverb pot should be after the 470K resistor R11, directly on the grind.
Or just skip them, the new JK don't have them at all

[dorrisant]

Nice job dorrisant !

No problem, glad to get this out there.

If you like the voltages for the old and new JK, let me know.

Yes, please post them both. I will probably add these to the first post when everything is done and sorted.

Also Jim did increase the screen resistors to 2X4K/10W on his later models.

I will try the original values first but plan on changing them to 4k to see/hear any differences...

noticed another error on the schematic.
The diodes D8-9 after the reverb pot should be after the 470K resistor R11, directly on the grind.
Or just skip them, the new JK don't have them at all

Ok... I see there is a difference between the schematic I posted and the old one floating around. Maybe you have some info that you are referencing that explains this...? Please elaborate if possible. No offense, I believe you are correct. I just want to get this one right for all to see. Thanks for picking it apart!

Btw... I will be starting to get into this build very soon. I still have to work the time in around paying jobs. Paint has dried on the donor chassis. Still have to punch holes in the chassis plate and then it should go much faster.

[dorrisant]

Ok... Some errors were found and corrected...

1) The placement of R11 470K on the schematic. Thanks oj.

2) C20 value - 0.0033µF on my layouts... I had it as 0.033µF. This was changed on all layouts including the zip files.

Now for a progress report...

I have cut all of the holes., well most of the holes, required in the new chassis top plate. Cut and drilled the circuit boards... populated them and got them mounted. The PS board center support was drilled slightly off-center. It shouldn't matter if no one looks at it. Don't look at it!

I'm not sure about outer foil orientation... May have to turn them around.

I will probably wire up most of the preamp before I mount the plate to the chassis just because it will be easier now. Now off to see if this layout will work or not... Oh crap! I forgot about the reverb TX and the jacks!!

*** Updated 12-26-16 ***

[Smokebreak]

That looks killer!!

[dorrisant]

Arrgghhh!!! I found more errors in the wee hours... I will repost and explain later.

Happy holidays to all!

[JazzGuitarGimp]

Nice looking build, Tony! Would I be correct in assuming your "flat plate" chassis will be bolted to an aluminum rim?

[dorrisant]

Yes, the chassis is steel though.

[dorrisant]

Ok... Moved one leg of C8 over to the correct eyelet on my board.

Found out that what was labled R3 should have been R32.
Found out that what was labled R6 should have been R30.
Found out that what was labled C9 should have been C19.
Found out that what was labled C? should have been C18.

The other parts are located off-board, at the socket.

I updated all of the previous files that were affected.

Below is a picture of the painted chassis... you can see where the chassis plate will bolt down.

The layout seems like it will work so I will proceed when time permits.

Let me know if anyone sees any more errors.

[dorrisant]

Question...

I don't have a bias tap so I was thinking of just tapping the HT secondary with a 220k over to the 470Ω resistor of the bias supply. Anyone see a problem? I will install a jumper in place of where the bias rectifier diode is located now and place the diode further up stream, of course. I was looking at a Marshall 186 for reference...

If this idea sounds legit, it will be very easy to make the board change anyway.

Another picture to show how the parts fit...

[xtian]

Your bias plan should work fine. You may have to adjust the dropper resistor value, so just tack it in while testing. Are you going to have an adjustment pot?