Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Foreplay III => Topic started by: trioid on March 21, 2011, 09:27:59 AM

Title: Can the FPIII run E80CC / 6085 in place of 12au7?
Post by: trioid on March 21, 2011, 09:27:59 AM

Hi Doc, or well informed others. In the search for a replacement Tele 12au7 I ran across the E80CC / 6085. The filament current is 0.3 A vs. 0.15 A. Is that asking for trouble?? I don't see any other problems, but higher gain....

Title: Re: Can the FPIII run E80CC / 6085 in place of 12au7?
Post by: Doc B. on March 21, 2011, 10:31:39 AM

The heater current is OK, as the PT-3 is rated for about 1.8amps DC at 6.3V. I would be inclined to avoid a higher gain tube, but it won't hurt anything. The specs are a bit different so you may see the plate and cathode voltages shift a bit. PJ did a list of subs for the 12AU7 back in the FP1/2 days (including e80cc) that might give some insight:

http://www.bottlehead.com/smf/index.php/topic,38.0.html (http://www.bottlehead.com/smf/index.php/topic,38.0.html)

Title: Re: Can the FPIII run E80CC / 6085 in place of 12au7?
Post by: trioid on March 21, 2011, 10:45:48 AM

Hi Doc,

I owe you one, again. Many thanks

Jim

Title: Re: Can the FPIII run E80CC / 6085 in place of 12au7?
Post by: Grainger49 on March 21, 2011, 12:53:13 PM

Here is a list of FP 1 & 2 tube equivalents:

http://www.bottlehead.com/smf/index.php/topic,1027.0.html

Edit: the FP III circuit works the same but with improvements all around.

Title: Re: Can the FPIII run E80CC / 6085 in place of 12au7?
Post by: trioid on March 21, 2011, 04:59:51 PM

Hi Grainger,

Thanks for the inputs.

Jim