tranny orientation

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Jonas Gemini
Hey get your own solder
Posts: 299
(2/11/04 8:10 pm)
 tranny orientation
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 I am working on a chassis layout and it looks like it is going to work best with the laminations on the output and the power tranny to be in the same orientation (both are standup design). How far apart do they need to be to avoid hum?

Should I diffentely put them at 90 degrees and go with the slightly longer run on the wires?

Jonas

Edited by: Jonas Gemini at: 2/11/04 9:26 pm
 
gammelnalle
Junior tube assistant
Posts: 7
(2/12/04 2:42 am)
 Re: tranny orientation
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 O Connors and other states that they should be off axic by 90 degrees to avoid that they combine their fields.
 
b4yourtime
Junior tube assistant
Posts: 70
(2/12/04 2:52 am)
 Re: tranny orientation
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 I use a 22" long chassis and I mount them at opposite ends facing the same way with the choke in the middle and I mount the tubes so they are within the inside distance of the transformers and the amp is very quiet when on.
Doug C.
 
6G6
Junior tube assistant
Posts: 76
(2/12/04 8:01 am)
 Re: tranny orientation
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 B4yourtime has the easy answer.
That should work fine and as a side benifit the amp should balance a lot better when you carry it.
If you really want to turn one of them 90 degrees, it is still possible. You can get longer screws to mount one of them horizontally. It will mean having to bend two of the standup tabs over to keep them out of the way, but if you turn that end away from the open side it won't show and they can be bent back and used if that trans goes into another amp later.
If you do that, I'd use the PT, just because it is probably bigger and sinking one bell into the chassis will keep the height of the trannys more even.
 
Jonas Gemini
Hey get your own solder
Posts: 300
(2/12/04 8:53 am)
 Re: tranny orientation
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 thanks,

I rethought this and decided to turn the output 90 degrees from the power transformer. I put the choke in the same orientation as the power transformer.

Thanks

Jonas
 
coap01
Junior tube assistant
Posts: 96
(2/12/04 9:15 am)
 transformer spacing
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 i was actually wondering about this myself, the optimal orientation/spacing. Whats interesting is that i've seen high end mono blocks that have transformers pretty much one right against the other.

Some have the "bells" (for the lack of a better term) of one transformer, facing the up/down, and the other transformer facing left/right. i would imagine that way is probably the best. after all, hifi amps cover much wider freq. range then guitar amps, so if it works for hifi, it will work for guitar.

the other thing to consider is the lead length of OT wires. shorter=better. i've yet to figure the best way to deal with this, and still keep an amp thats evenly balanced.
 
ganzonimx
Hey get your own solder
Posts: 370
(2/12/04 11:06 am)
 Re: transformer spacing
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 Just for curiosity I like to show that pic. It's a stereo jukebox amp that had four 7686 tubes. Unfortunately the OT's are 8000:16 and the PT is a 400-0-400 with no 6.2V winding. One of the OT's is placed in the same orientation like the PT just 1/2" apart. I hadn't the chance to here that amp, so I don't know if one of the channels had hum coming from the PT.



Cris
 
eddiejg
Senior tube assistant
Posts: 226
(2/12/04 12:11 pm)
 Re: transformer spacing
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 My $0.02-
I put the PT on the end & toward the front so the rectifier & power tubes can be aligned along the back edge on that side of the chassis.
The OT goes along the back edge next to the last power tube, & the preamp tubes are along the back edge on the other side of the OT.
The turret board runs from the preamp end to next to the PT.
The 1st amp with a choke I just built, the choke went a few inches over from the PT, right above the power caps on the inside of the chassis.
This general layout results in almost no lead longer than 6 inches, all ac is on one end, preamp & power sections are separated & these amps are quiet.
Only drawback- the amp is definitely NOT balanced.
-Ed

 
 
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