What tube instead of 7189

[refference]

Hi Potqieter ,

Thanks for your post .
Your comments are always wellcome !!

Regards ,

Carlos

 

[Miles Prower]

Re: Ok, here I am again...

But the 807 looks so much cooler....(or so much hotter in this case).

Yes they do.

A few years ago I used triode'd pp807 (as per datasheet) with an EL84 output transformer, power output was about 7W but with sooo sweet sound.

Sound pretty darn sweet in pentode mode: 6.95db(v) of local feedback on the inner feedback loop with 12db(v) of gNFB. Although that requires 6.6K (p-2-p) : 8.0R OPTs.

So....what's it gonna be ???

Jim

Can't go wrong with 6V6s.

 

[refference]

Hi Tubelab ,

Congratulations ,
Your post is really amazing , correct , and goes straight
to the “ X point ” .

When I said 6L6 ( generically ) , I thought that was obvious ,
( at least for me ) that we were talking about 6L6 ( metal ) and
6L6 G / GA versus 807 , because I was taking the comparison
into the same time-line .
That’s the reason because Potqieter said :
-- Carlos, your max. voltage ratings for the 6L6 seem to be
a little outdated;...... ( my time-line really was outdated )

I agree entirely , when you ( tubelab ) said that 6V6 is the
“textbook” or the academic answer to the Jim’s question, and
more , if he does not want to be so academic , he really has
a lot of possibilities , obviously within the 3 taps output tranny
parameters ( 8000 ohms plate to plate x 25 Watts ) .

As I have said , I “see” 6V6 and 6L6 ( side by side with 6BQ5 /
EL84 ) as the stronger “candidates” to the Jim’s amp , IF (... I
said IF ) he wants to keep the choice among “textbook”
options .

At least for me , the discussion about 6L6 versus 807 is
over .
Thanks again to Tubelab and Potqieter for their posts .

Regards for all ,

Carlos

 

[Johan Potgieter]

Yah, just to round off:

When I said "the same" I was perhaps not unequivocal - my apologies. I meant characteristics-wise excluding power ratings. The higher max. plate voltage resulted from a different mica wafer (with cut-out as mentioned); higher dissipation from better heat radiation by way of a larger g1 cooling fin, direct mounting on pins instead of a glass tongue for some extra heat conduction through the pins and a slightly larger anode area at the splices.

I have a row of cut-open tube displays for the show; there the internal geometry of all 6L6s measure the same.

Incidentally, I read that some crazy hams operated a pair of 6L6s (metal) in a bath of transformer oil - to dissipate 150W for short periods! Cool, man.

And Jim, congratulations and every good wish for your future "partnership"!

Thanks all.