Stereo 6v6 amps in one cabinet - proximity considerations

[pjd3]

Hello,

This is a very loose and early considered idea that I'm sure has been all done before but, in the name of compactness (or as much as can be garnered), I had a concern about what can be in closer proximity, and what needs to be distanced.

So, while I'm aware of the standard rules of "PT/power on one side of chassis, input on other side", "OT away from PT", and all of those prudent rules that play out in practice, my question focuses on how to look at Output transformers, and the consequences of two output transformers being somewhat close to each other in a 2-channel amp (two full amps in one chassis).

The reason I am specifically focusing on output transformers in proximity to each other, is that while creating a layout drawing of possibilities for say, two deluxe reverbs (no vibrato) in the same chassis, I found that the best compromises I could come up with still left the output transformers from each amp relatively close to each other. Now, while I have gone as far in the past builds to experiment with "The headphone trick" for placing an OT, I need to admit that I as of yet cannot clearly conceptualize the modes in which 2 OT's would or might interfere with each other's performance. Where there is some considerable current especially in the secondary taps that provide some considerable current to the speaker, can I expect enough magnetic radiation emitted to interfere with another OT say, 3-4 inches away from each other? While I'm sure in theory there has to be magnetics from one creating some level of induced signal in the other, it is just difficult to assume or establish just how much that would be, and would it be enough to compromise the practical performance of each output transformer.

I know this is probably a question that doesn't have a standard and classically known answer to it, but wanted to put it out there for speculation, just in case anyone had run up against the practical issues that might arise. I'm thinking right now that the Hi-Fi guys may have some more acquaintance with something like this than guitar tube amp guys.

Thanks for your time on this!
Best,

Phil D,

[pjd3]

Actually, I take a tiny bit of this back - there is a layout I found that enables the two OT's to be moved away from each other if I moved the power tubes toward the middle of the amp, which may be just fine. As long as the decreased proximity between the PT's on the end are still OK with the OT"s having been brought closer to them. That I can determine with the "Headphone trick" and even rotating the OT's would be OK. It might not looks as nice but, I did find by experimenting on another amp that rotating the PT's and OTs can have even a more effect on creating quiet OT secondary taps than proximity even has to offer - but, it did end up being a compromise of some proximity coupled with some rotational angle. We have the right to do that!

thank you,

Best,

Phil

[xtian]

Phil, just look at the zillions (ok, hundreds) of stereo amp chassis for home stereos of the 60s.

[pjd3]

Hi Xtian. I have and will continue to see how they arrange components in terms of layout on the home stereo tube amps.

What I'll need to do is figure how that will translate to a 2 x 10" speaker combo with full symmetrically laid out controls on a front panel with the standard Volume/Trb/Mid/Bass/Maybe reverb/maybe adjustable NFB/Presence for two independent channels. I'm sure that there are many layout schemes for many applications and preferences. My question was more geared to how output transformers effect each other should they get too close. That was the element I was having the collision about when trying different layout drawings. I will look at many hi fi tubes amps more closely to see what has been done with output transformer proximities. If I can keep out of trouble there, I think this little plan of mine might work out OK.

Thank you!

Phil D

[xtian]

My question was more geared to how output transformers effect each other should they get too close.

No interaction at all, in my experience.

[Stevem]

If the level of Genius that Designer McIntosh had in him was happy to make a stereo tube amp with its major components laid out like this then suffice to say that you would be fine to do the same for your build.

[pjd3]

Well Stevem,

I certainly can say it generates a lot of hope in me to see a layout like that that works wonders, while knowing that I have a hell of a lot more area to park my transformers in than that. No excuse for any buzz/hum from my up and coming stereo amp!

thank you,

Phil d.