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'load lines for dissimilar output tubes?'
Author:tapehead ted (registered user: 6 posts )
Date: Thu, Mar 16th, 2017 @ 16:41 ( . )

Thanks for your reply.

The whole scenario I relate in my initial post is, to clarify, envisioning the same tap and load for both tube types. I do, I believe, understand the basics of the reflected load idea. This is assuming that the speaker load remains the same, and thus the reflected load remains the same from anode to anode.

Each tube is looking at the same 4k load, but in the same way it looks like an 8k load to each of two pair of similar tubes, at assumedly the same current, it looks like 8k, possibly plus or minus some amount, to each of the two dissimilar tubes. I just have been nagged by the idea that some difference between the two dissimilar tubes, notably with the 6v6 and 6L6 that one is quite a bit larger than the other, would influence the load lines of the two dissimilar tubes so the load lines were not identical. I was struck by the idea that perhaps the different currents the two tubes were handling would be the crucial difference. Perhaps in fact both load lines are identical, just like I was using two tubes of the same type and at the same current. Hopefully someone has an answer to that- I look forward to hearing more about it.

Is there really a possibility that this could damage the output transformer, assuming that it is rated to handle the total current? I can't see how that would happen- I would think the two dissimilar tubes on each side of the output transformer would appear to the transformer just like some other composite single tube.

FWIW I have heard and used this combination in an amp a friend built that was supposed to be able to handle one or two pair of 6v6 or a single pair of 6L6. (This with a 4.2K transformer switchable to 2,4, or 8 ohms.) One pair of each sounded really good in that amp, adding a whole different dimension to the 6L6 tone while still having the clear lows of the 6L6, which I am quite addicted to, and breaking up much more smoothly than the 6L6 alone. Unfortunately, that amp eats tubes for a variety of reasons including that the rectifier tube is really too small for anything more than a single pair of 6v6's, the power amp grid leaks are too high a value, the screen stoppers are tiny, among various others.

So I have been inspired to design an amp addresses those and several other problems and makes life as safe as possible for 6v6's and 6L6's at the same time.

So I've been trying to determine what was going on as far as loadlines when I was hearing those lovely sounds through that other amp. I suppose I could just conclude that the combination works nicely with that anode to anode load, and move ahead with it, but I'm hoping to learn some more about the dynamics of it.

Thanks again.

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Replies:
--* load lines for dissimilar output tubes?
3/17/2017 @ 09:23--Malcolm Irving
3/17/2017 @ 14:17----CChurchill
3/17/2017 @ 14:20------CChurchill
3/17/2017 @ 14:54------Malcolm Irving
3/17/2017 @ 19:51--------CChurchill
3/18/2017 @ 13:49----tapehead ted
3/18/2017 @ 15:21------Malcolm Irving
3/18/2017 @ 15:35--------tapehead ted

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