Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: worth on August 19, 2011, 12:28:03 pm

Title: parallel 6V6 5F1 output primary ?
Post by: worth on August 19, 2011, 12:28:03 pm
In about an hour I'll power up this build , but I need a recommendation for the OT primary impedance. The OT is a Doberman/ Heyboer with a choice of 2.5K , 4K , or 6K primary. I'll be using the 8 ohm secondary.
Title: Re: parallel 6V6 5F1 output primary ?
Post by: stratele52 on August 19, 2011, 12:37:08 pm
You talk about 2 parallele  6V6 not push-pull.  A single ended transformer with a primary of 4 k to 5 K work fine.
Title: Re: parallel 6V6 5F1 output primary ?
Post by: DummyLoad on August 19, 2011, 01:21:30 pm
Quote from: worth on August 19, 2011, 12:28:03 pm
In about an hour I'll power up this build , but I need a recommendation for the OT primary impedance. The OT is a Doberman/ Heyboer with a choice of 2.5K , 4K , or 6K primary. I'll be using the 8 ohm secondary.

2K5

adjust Rk to set Pdiss ~20 to 22 W for both 6V6.

-DL
Title: Re: parallel 6V6 5F1 output primary ?
Post by: tubeswell on August 19, 2011, 07:01:48 pm
Either 2k5 or 4k for 2 x parallel 6V6s
Title: Re: parallel 6V6 5F1 output primary ?
Post by: PRR on August 20, 2011, 12:45:24 am
> I'll power up this build , but I need a recommendation for the OT primary impedance

Why? Power-up, try them all. Won't hurt the amp.
Title: Re: parallel 6V6 5F1 output primary ?
Post by: Geezer on August 20, 2011, 04:56:30 am
Quote from: PRR on August 20, 2011, 12:45:24 am
> I'll power up this build , but I need a recommendation for the OT primary impedance

Why? Power-up, try them all. Won't hurt the amp.

Right on!    You may be surprized @ what your ears "recommend"  :icon_biggrin:

G
Title: Re: parallel 6V6 5F1 output primary ?
Post by: PRR on August 20, 2011, 11:52:51 pm
> You may be surprized @ what your ears "recommend"

Also: there is not sufficient data presented to ball-park a "right" answer. Wanna know plate voltage and current. Since this is not a stock 5F1, and may use un-stock PT, even comparison to "similar" amps may be folly.

As long as you have a speaker on a near-right impedance tap, you can use ANY primary impedance on cathode-bias amps. Get different power and flavor, but shouldn't hurt anything.