6V6 in triode connect mode

cominup · 29th April 2005, 03:29 AM

Dear all,

Pls, see attachment, RCA manual 6V6GTA. They said that in triode connection mode, at 250V plate voltage, plate resistance is 1960ohms.

Have you ever tryed this one before? Or could you suggest schematic to operate this mode. How about SRPP 12AT7 for driver?

Thanks in advance

Cominup

Sch3mat1c · 29th April 2005, 08:39 AM

Sure. Mind that you'll get one watt if you're lucky. 6V6 is a skookum pentode but at best a weak triode only suitable for heavy driver applications.

Tim

EC8010 · 29th April 2005, 12:36 PM

"Skookum" pentode? Qu'est que c'est?

audiousername · 29th April 2005, 12:44 PM

Quote:

Originally posted by EC8010
"Skookum" pentode? Qu'est que c'est?

Err... sort of "good"

http://en.wikipedia.org/wiki/Skookum

EC8010 · 29th April 2005, 12:50 PM

Thank you for that. No wonder I hadn't heard the word before...

planet10 · 29th April 2005, 05:57 PM

Quote:

Originally posted by audiousername
Err... sort of "good"

http://en.wikipedia.org/wiki/Skookum

Thanx for that... the word has been in my vocabulary for ever... now i know where it came from.

dave

leadbelly · 29th April 2005, 06:03 PM

Quote:

Originally posted by cominup
Or could you suggest schematic to operate this mode.

http://audiotropic.netfirms.com/blurb1.html

PRR · 1st May 2005, 01:55 AM

> RCA manual 6V6GTA. They said that in triode connection mode, at 250V plate voltage, plate resistance is 1960ohms.

Any pentode can be a triode. But in a pentode, the screen grid sucks big current even when plate voltage is low. So a pentode is designed for a high Mu (G1 to G2), 10 or 20, for good power sensitivity. In a triode, current falls when plate voltage falls. You want a low Mu, like 5, to reduce this effect. 6V6 Mu is 10. So it is OK but hardly great as a triode power amp.

For 1935, this was very good performance. It might still be pretty good for 6V 0.45A heater power. It won't knock your socks off.

I've used the 10 Watt plate rating, which really applies to TV V-sweep duty. SET duty is tough too, but perhaps less likely to gross abuse than cheap TV work, so at your discretion you could run 12, 14, even 18W in your 6V6 (they are tougher than the book says).

Two possible operating conditions:

B+ = 350V
Iq = 28mA
Vpk = 210V
Ipk = 28mA
load = 7.5K
power = 2.8 Watts
grid = 0V/-30V/-100V
THD = gross
maybe 1.4W with listenable THD at 320V, 30mA, -25V bias

B+ = 240V
Iq = 40mA
90V pk
22mA pk
load = 4.1K
power = 0.9 Watts
grid 0V/-14V/-33V
THD ~ 10%

Ah: RCA's 1940s datasheet gives suggested values for triode operation, somewhat better than my estimates because they push the 14W rating for audio triode operation.

> How about SRPP 12AT7 for driver?

Huh? It only needs 15V-20V of drive, with 250V-300V of supply voltage available. No reason to muck it up with complicated drivers. For zero-feedback operation, a 6SN7/12AU7 is plenty of gain. If you want damping better than 2, use 6SL7/12AT7 and take some NFB around everything.

TJ · 2nd May 2005, 03:12 AM

I hv seen a lot of 6v6 schmatic connect in Push pull mode but very few in UL , why ? bad sound or what ? please let me know . cheers

planet10 · 2nd May 2005, 04:40 AM

Quote:

Originally posted by TJ I hv seen a lot of 6v6 schmatic connect in Push pull mode but very few in UL , why ? bad sound or what ? please let me know . cheers

6V6 was never designed with the intent of UL operation like the EL84 or EL34 were.

dave

29th April 2005, 08:39 AM	#2
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	Sure. Mind that you'll get one watt if you're lucky. 6V6 is a skookum pentode but at best a weak triode only suitable for heavy driver applications. Tim __________________ See my Electronics webpage -- the home of Vacuum Tube Drag Racing. The key to being a successful Audiophile: "I reject your reality and substitute my own!"

29th April 2005, 12:36 PM	#3
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	"Skookum" pentode? Qu'est que c'est? __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

29th April 2005, 12:50 PM	#5
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Thank you for that. No wonder I hadn't heard the word before... __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

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1st May 2005, 01:55 AM	#8
PRR diyAudio Member Join Date: Jun 2003 Location: USA	> RCA manual 6V6GTA. They said that in triode connection mode, at 250V plate voltage, plate resistance is 1960ohms. Any pentode can be a triode. But in a pentode, the screen grid sucks big current even when plate voltage is low. So a pentode is designed for a high Mu (G1 to G2), 10 or 20, for good power sensitivity. In a triode, current falls when plate voltage falls. You want a low Mu, like 5, to reduce this effect. 6V6 Mu is 10. So it is OK but hardly great as a triode power amp. For 1935, this was very good performance. It might still be pretty good for 6V 0.45A heater power. It won't knock your socks off. I've used the 10 Watt plate rating, which really applies to TV V-sweep duty. SET duty is tough too, but perhaps less likely to gross abuse than cheap TV work, so at your discretion you could run 12, 14, even 18W in your 6V6 (they are tougher than the book says). Two possible operating conditions: B+ = 350V Iq = 28mA Vpk = 210V Ipk = 28mA load = 7.5K power = 2.8 Watts grid = 0V/-30V/-100V THD = gross maybe 1.4W with listenable THD at 320V, 30mA, -25V bias B+ = 240V Iq = 40mA 90V pk 22mA pk load = 4.1K power = 0.9 Watts grid 0V/-14V/-33V THD ~ 10% Ah: RCA's 1940s datasheet gives suggested values for triode operation, somewhat better than my estimates because they push the 14W rating for audio triode operation. > How about SRPP 12AT7 for driver? Huh? It only needs 15V-20V of drive, with 250V-300V of supply voltage available. No reason to muck it up with complicated drivers. For zero-feedback operation, a 6SN7/12AU7 is plenty of gain. If you want damping better than 2, use 6SL7/12AT7 and take some NFB around everything.

2nd May 2005, 03:12 AM	#9
TJ diyAudio Member Join Date: Sep 2001 Location: UK	I hv seen a lot of 6v6 schmatic connect in Push pull mode but very few in UL , why ? bad sound or what ? please let me know . cheers

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