Long-Tail Pair (Part 2): Adjusting the Long-Tail Pair
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- เผยแพร่เมื่อ 28 ส.ค. 2024
- Before adjusting the bias of the power tubes of a Push-Pull amp (Class AB), be sure the phase splitter outputs have the same voltage swing. This video discusses which resistors to be adjusted. If the outputs are not operating at the same voltage swing, then the power tubes will simply magnify the problem and produce unwanted distortion.
Original Work, Copyright 2020 James D. Whiteside, II all rights reserved, For consideration only, no reproduction without prior permission.
Where were you all my life ? You´re the man, how is it possible that I never been notified of your videos. For the past 7 years the only videos I watch are tube related, mostly Guitar and Hi-Fi. I think the reason is that most of your videos have the comment section disabled, so somehow it stops youtube algorithm to recommend your videos. Yo have 4840 subs , you should have 484000 at least. All I can say you are the best engenieer I´ve seen in youtube in the las 5 to 7 years. Thanks for sharing your knoledge with us common mortals. AND excuse me for grammar and other mistakes, as you can tell English is not my main language. Cheers!
“…because your Commodore 64 is in the shop and need something to do”. Nice wrap up!
Very nice! Thanks.
Hi, my phase inverter doesnt have the out of phase signal, both sides has the same wave, could help me?
Sorry, but my english is bad.
Yes, please send me an email (see my TH-cam website) and let me know the schematic you are using.
Thanks for the video, it really helped me out. It has raised a question though, that I'm having difficulty wording: Given that the DCR of an output transformer differs between the two sides of the primary winding from the centre tap, and assuming the output pentodes are the same and well matched, which side should connect to which half cycle? I've tried both ways round and there is a difference.
I am assuming that the primary has 3 wires and you are measuring between the tap and each side.
They normally differ by 10 Ohms and that is not critical to the tube plate loading. For example: assume the required reflected plate loading is 4000 ohms (at say 1K Hz). A 10 Ohms mismatch means one plate will be loaded at 4010 Ohms and the other will be loaded at 4000 Ohms at 1K Hz. The reflected plate loading is the same. All the other component values in the circuit are only +/-20% anyway (either static value or operationally) so a few ohms difference DCR is not a problem.
@@deepblueharp thank you for the response.
@@deepblueharp Thanks, I think your correct, the difference in DCR will have little or no difference to the transfer of an AC load. Am I right in thinking that only at idle, one side will be pulling slightly more current than the other?
@@jamesbennett678 in push-pull, the bias current is going to be near zero. So, the small difference in DCR is still not significant.
@@deepblueharp I think the important issue here is the need for a balance control for the output tube bias, It sets the idle current even for both tubes (statics) and reduces hum at least, so you can get away with less filtering in the power suply plus cancelling other noises the power rail injects in the primary center tap (b+). Of course I´m thinkig after the splitter itself. Again sorry for my grammar and other mistakes, english is not my main language.