Wreck Junior.

[slajeune]

Hi Greg,

if the comment was oriented at me, I have to say that there are a LOT of more talented people here that build a lot more stuff than me!

Cheers,
Stephane.

[slajeune]

Forgot to post this picture earlier. My derailment is in a combo. The faceplate is a very cheap 1/16" wood panel that was very clumsily engraved and coated.

http://www.sophtamps.ca/images/derailme ... _wreck.jpg

Cheers,
Stephane.

[kec]

Can someone check my layout for socket placement? I don't want to screw this up.

My chassis is 8" deep x 12" wide. I basically followed the dim's of the Express for V1 & V2. Now I have to figure out for the EL84 and octal mod sockets - one at a time, of course

Any ideal places where power tubes should be? Attached pic is what I was thinking.

[evan]

Hi Ken:

Your tube layout looks okay to me.

I would recommend checking your transformer layout with the "headphone trick" --- wire a socket on yout OT secondary for your phones and power up the PT primaries. I think you will find some 60 Hz hum present in the layout you have (based on my experience with Hammond trannies). It will probably decrease to an acceptable level if you rotate both transformers 90 deg.

-Evan

[kec]

Hi Ken:

Your tube layout looks okay to me.

I would recommend checking your transformer layout with the "headphone trick" --- wire a socket on yout OT secondary for your phones and power up the PT primaries. I think you will find some 60 Hz hum present in the layout you have (based on my experience with Hammond trannies). It will probably decrease to an acceptable level if you rotate both transformers 90 deg.

-Evan

Thanks for your input. I did the tranny layout just as allyn did - see first post - although his OT is more off center than mine. I was always told that you want one of the trannys 90 deg. of the adjacent tranny - similar to inductors in crossovers.

On the "headphone trick". This is new to me. Is that all I hook up? Headphones from OT output, Power primaries (PT) only? with load or no load? Please elaborate. Thanks!

[kec]

On the "headphone trick". This is new to me. Is that all I hook up? Headphones from OT output, Power primaries (PT) only? with load or no load? Please elaborate. Thanks!

Never mind. I found out here: http://ax84.rru.com/FAQs/general.html#hp-trick

[evan]

Yes, you have it right on the headphone trick. No load is required on the PT. Obviously, be careful with those PT secondaries. Small wire nuts are handy for this. If you have multiple taps on the OT, use the 16 ohm output.

On the orientation, yes, in general (there are occasional exceptions like the hammond 125dse OT) there is minimum hum with laminations oriented at 90 degrees. In my experience, the one you have there is "second best" and by turning ea transformer 90 degrees the layout will improve. Try the headphone trick and see. With the transformers so close together, I think this is well worth your while. Obviously you could hook up your speaker cab in place of the headphones and get "another opinion". This hum comes through even in standby.

[kec]

Evan, I'll try it today.

Thanks!

[kec]

Just did the test. No hum with my current orientation as pictured If I rotate either tranny 90 deg., hummmmm

BTW, I'm using the OT from musicalpowersupplies.com

[evan]

Cool.

Always worth doing on a small chassis.

-E.