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Post by 6strang (aka Paul) on Apr 21, 2011 11:55:29 GMT -7
Just ordered some Tung-Sol EL-34B power amp tubes, and 12ax7's for the amp. I know Doc likes to bias between 28mA and 32mA. I read that Myles suggested 36mA. Any advice or comments are appreciated!
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Post by teleric on Apr 21, 2011 12:39:36 GMT -7
I was thinking the last time I biased my 6545 with EL34s (25 watters), I biased at 35ma (65% is usually what I shoot for), but I'll check it out next time I get to our practice space where I keep my 6545.
I put a small sticker with date and measurements on the chassis every time I bias/retube. I do the same thing on the preamp tube retainers every time I test a preamp tube and use it in an amp. Maybe just me being anal-retentive, but it does let me know what I have in there at a glance.
I've run a couple of NOS Tung Sols in the 12AX7 slots before and they sounded great - not sure how they'd compare with the current production stuff.
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Post by teleric on Apr 22, 2011 9:58:18 GMT -7
32 ma is what my amp was biased at last time I set it up (per my earlier post).
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Post by 6strang (aka Paul) on Apr 22, 2011 13:46:45 GMT -7
Thanks! I will keep that in mind next week when changing out power tubes.
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Post by drew on Apr 24, 2011 13:31:52 GMT -7
Hey Paul. When I picked up my 6545 it had EH EL34's with a plate voltage of 432v and bias at 31ma. I'm using a GT 12ax7-M phase inverter (came with the amp, in fact all of the 12ax7's were GT 12AX7-M) and Groove Tube #7 EL34's. The plate voltage is 420v so I set the bias to 34ma using the voltage/current chart from the website below. Then if I recall tweaked to what I liked but can't remember where I set it. Main Page www.diyguitarist.com/GuitarAmps/PowerTubeBias.htmby clicking on the EL34 link www.diyguitarist.com/Images/BiasChart-EL34.jpgDrew
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Post by 6strang (aka Paul) on May 6, 2011 20:06:19 GMT -7
Update: one of the Tung-Sol's was bad...got a refund from the seller. Installed a new set of Gold GT EL34's...Bias to 32.5 mA...and she is a rockin' machine! Thanks for all the input!
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