I have an amp which is designed with a parallel push-pull topology. So 4 power tubes per channel. Circuit is designed for EL34 but i got with Genelex KT77"s (which i run in my SE amp and quite like, although I may dable with 6L6''s if I can find a good deal, damn 8 tubes). Best i can determine with my very limited knowledge is that the OTP's should have an input impedance of 5K (out to 8 ohm speakers). So finally to the actual question, if it's 5K with a simple push pull design - how does having 4 in parallel effect this?
If two PP valves need 5k, then four valves need half as much, or 2.5k.
Why say, If? If the design was done properly for PPP and EL34, it won't be 5K to start with. Why guess about the OPT's primary?
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2500 would be about right, but you can easily measure it.
I won't describe the process nearly as well as youtube can, but it's easily measured with basic test gear...
I won't describe the process nearly as well as youtube can, but it's easily measured with basic test gear...
I'm not guessing I'm trying to understand how the circuit would work. I think you've misread my question.
Perhaps, but I read your intention to was to swap the tubes out to 6L6 from EL34. And that the design is PPP and that you have assumed the primary ''should'' be 5K and if it is... Then you ask how a PP at 5K should be calculated for a PPP design... So I'm wondering where the '' should be 5K'' is coming from, if not a guess.
So then why do you say your transformers are 5K? Do you suspect they aren't the correct ones for your PPP amp? The choice for a transformer is somewhat dictated by the class of operation it's forced to run under, the idle current rating, drive limits... before swapping out your EL34, you should have some good operating point parameters established. The cost difference between EL34 and 6L6 just isn't big enough to ''experiment'' with if the possibility of making a wasted purchase is this high. You have biasing and plate voltages to consider.
Just ring to learn/ understand the theory so when I pile around inside the amp I know what to expect.
Perhaps worth identifying the amp, if you have a service manual or schematic, and if you've serviced it and measured anything to date.
Is this amp the one you posted on here: https://www.diyaudio.com/community/...-se-el34b-yes-nother-one.356312/#post-7950374