2w Sub Miniature Express

[gary]

Has anyone had opportunity to compare philips with sylvania 6112 tubes and formed a preference?

If so, could you describe the difference?

[azrael]

So what's the skinny on this amp kit?

How much does it cost, what's included, what do I need to get/build myself?

[paulster]

So what's the skinny on this amp kit?

How much does it cost, what's included, what do I need to get/build myself?

http://www.hallamplification.com/

[azrael]

awesome, thanks.

[JimboM]

Got the Lil Devil kit up and running and am quite happy with the amp. The one area with *my build* that I'd like to see if I can improve would be a reduction in the 60 cycle hum. Don't know if this is the nature of the beast or not.

Any advice would be greatly appreciated!

JimboM

[MCK]

JimboM, great to hear its working! I built two of these great little amps and they are both a little different. One has a little more 60 cycle hum and the other has none of it but has more RF interferance. I think this perhaps means how we execute the lead dressing is extremely important. I will go back and review & redo at some point but I just can't get myself to stop playing these things long enough.

So in short, I don't think the 60 cycle hum is a definitive characteristic of the Lil' Devil and it should be something we can get rid of to a large degree. Hope this helps. All the best.

[gahult]

JimboM,

Did you install a hum balance pot??

See:

http://ampgarage.com/forum/viewtopic.ph ... &start=210

Left end of board..top view.

I had some hum in mine too but the balance pot took care of it.

Gary

[MCK]

Gary, do you mind posting more details about this mod? Value of the pot and where it connects to? Thanks much!!!

[JimboM]

Thanks Gary! I read that section again. Seems that using the CT of the Heyboer negates the hum pot according to Dana's subsequent post. But I'm pretty ignorant on this, so...

MCK, thanks for the suggestion. I'll play with the lead dress a bit more and report back.

All thoughts welcomed.

[gahult]

Here is what I did with Dana's help.

The 1.5 ohm resistors are not needed if your filament voltage is OK.

Mine was up at 7.1v with the original Hammond PT so I had to drop it with the 1.5 ohm resistors Mouser Pt#:
660-MOSX3CT631RR15J 2@$0.36

The trimmer pot is a 200ohm single turn Mouser Pt#:
594-63X201 $2.37

The trimmer is across the filament wires/wiper to ground.

[IMG:336:378]http://i405.photobucket.com/albums/pp13 ... wiring.jpg[/img]

[IMG:300:253]http://i405.photobucket.com/albums/pp13 ... erside.jpg[/img]

[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01649.jpg[/img]

Hope this helps.

Gary

[UR12]

Got the Lil Devil kit up and running and am quite happy with the amp. The one area with *my build* that I'd like to see if I can improve would be a reduction in the 60 cycle hum. Don't know if this is the nature of the beast or not.

Any advice would be greatly appreciated!

JimboM

Jimbo before you do anything with the hum balance pot try just swapping the V1 and V3 tubes positions. If that doesn't reduce the hum try swapping v2 with v3. If it works you should hear a quiet amp.

[gahult]

Yup...that's the cure for the Hammond.

Forgot the CT Heyboer doesn't manifest this problem.

Didn't know which one you were using.

Hope you get it fixed.

Gary

[JimboM]

Dana and Gary.

Thanks for the help. I tried the swap with very little change. I went over all of the lead dressing and grounds and couldn't find anything there. Really appreciate the advice.

JimboM

[gary]

has anyone experimented with different brands of tube in their Li'l Devil ?

Do you have any preferences as a result? Can you comment on their relative performance/character ?

cheers

[dayn]

Here is a quick video I did, the description of the video explains the rig:

http://www.youtube.com/watch?v=KCpGv3M9tCs