(sorry for my english)
Hi, I am a total newbie with tubes:
I have a simple preamp with one Sovtek6922 anode output
( half one channel- half the other channel)
210 Volt ; anode resistor= 15Kohm ; cathode resistor=330 ohm
Cathode bypass= 220 microF
Now I want experimentate the sound of 2 sections in parallel ( each channel) at the same "work-point". I expect 1/2 Zout .
What is the correct values for resistors and cap?
Thanks advanced for your time
Cheers,
Inertial
Hi, I am a total newbie with tubes:
I have a simple preamp with one Sovtek6922 anode output
( half one channel- half the other channel)
210 Volt ; anode resistor= 15Kohm ; cathode resistor=330 ohm
Cathode bypass= 220 microF
Now I want experimentate the sound of 2 sections in parallel ( each channel) at the same "work-point". I expect 1/2 Zout .
What is the correct values for resistors and cap?
Thanks advanced for your time
Cheers,
Inertial
TubeCad results suggest that you could removed the resistors and capacitor from one side of your dual triode then jump pin 1 to 6, 2 to 7, and 3 to 8, and have safe operating conditions without changing actual values of the remaining components.
1/2 the z out @ 1.35 K, bias @ -2.65 volts, gain 29.6
dr._sleep
1/2 the z out @ 1.35 K, bias @ -2.65 volts, gain 29.6
dr._sleep
Thank you dr._sleep for the help!
Cathode and anode resistors remain the same. Now I am quiete.
Many thanks again. 🙂
Cheers,
Inertial
Cathode and anode resistors remain the same. Now I am quiete.
Many thanks again. 🙂
Cheers,
Inertial
incorrect
you need to half anode and cathode resistor,if you want same transfer characteristic
if you don't want same transfer cc... , it's another story
you need to half anode and cathode resistor,if you want same transfer characteristic
if you don't want same transfer cc... , it's another story
Oh, Thanks Choky!
Yes , maybe my bad english have caused mistake.
Yes I want exactly the same behaviour for the "double" that
I haved before with "single". Istinctivally I also have thinked
for Half-values of the two resistors .
I can go with safety!
Many thanks again Mr Choky! 🙂
Cheers,
Inertial
P.S.: Double values for the capacitor of cathode bypass?
Yes , maybe my bad english have caused mistake.
Yes I want exactly the same behaviour for the "double" that
I haved before with "single". Istinctivally I also have thinked
for Half-values of the two resistors .
I can go with safety!
Many thanks again Mr Choky! 🙂
Cheers,
Inertial
P.S.: Double values for the capacitor of cathode bypass?
Thought I'd offer the easiest way to go parallel:
"TubeCad results suggest that you could remove the resistors and capacitor from one side of your dual triode then jump pin 1 to 6, 2 to 7, and 3 to 8, and have safe operating conditions without changing actual values of the remaining components."
"incorrect says chokey
you need to half anode and cathode resistor,if you want same transfer characteristic
if you don't want same transfer cc... , it's another story"
If you keep the same B+ and half the anode and cathode resistors you will excede the recomended plate voltage for a 6922.
If my suggestion sounds crappy then change all components as others have suggested.
Sorry,
dr._sleep
"TubeCad results suggest that you could remove the resistors and capacitor from one side of your dual triode then jump pin 1 to 6, 2 to 7, and 3 to 8, and have safe operating conditions without changing actual values of the remaining components."
"incorrect says chokey
you need to half anode and cathode resistor,if you want same transfer characteristic
if you don't want same transfer cc... , it's another story"
If you keep the same B+ and half the anode and cathode resistors you will excede the recomended plate voltage for a 6922.
If my suggestion sounds crappy then change all components as others have suggested.
Sorry,
dr._sleep
do your homework without tube cad
every program is effective exactly as guiding hand is capable
I repeat-if goal is double S,half Ri, lowered noise and same transfer characteristic ,then you must halve both resistors;
in that conditions both triode systems will see same voltage and current as in previous -one triode- stage.
I have no doubt in your good will , but this is simply incorrect;
if you keep same resistors as for one triode,transfer characteristic will change;
depending of actuall circuit-maybe to worse,maybe to better....
every program is effective exactly as guiding hand is capable
I repeat-if goal is double S,half Ri, lowered noise and same transfer characteristic ,then you must halve both resistors;
in that conditions both triode systems will see same voltage and current as in previous -one triode- stage.
I have no doubt in your good will , but this is simply incorrect;
if you keep same resistors as for one triode,transfer characteristic will change;
depending of actuall circuit-maybe to worse,maybe to better....
Unfortunately I am now total absorbed by speakers and room
development.
The guy that normaly help me with tubes ( 66 years old) is total
dedicated with a phono preamp. I must have a lot of patience 🙂
Cheers,
Inertial
development.
The guy that normaly help me with tubes ( 66 years old) is total
dedicated with a phono preamp. I must have a lot of patience 🙂
Cheers,
Inertial
choky is right, for the same transfer, double S and half Ri, you need half the amount of cathode and anode resistor.
tie the mentioned pins together...(1,6 3,8 2,7)
i have done something alike, but then to fit a different tube in
my ecc99 linestage, has been replaced by 2 xe80cc.
when the 2 halves of the e80cc are used in parrallel, one e80cc is almost the same as one half of the ecc99. So i had to add a tube, and remove the feedback, but did not change any resistors (ra=9k, rk=220, ck=100uF)
sound is much more nice with these SQ tubes (lot more detail, open sound, ecc99 seems dark sounded compared to these)
i have to recalculate the nfb because open loop amplification has changed, but......
i think i prefer no NFB, and just be gentle with the volume pot 😀
when you would not change the resistors to half their value, the transfer curve will be different, but S and Ri will remain the same....+ there will be more current through rk, ra eg. bigger wattage needed
There will also be more current when you do half the resistors(best option!) but because resistance is less, wattage stays the same.
tie the mentioned pins together...(1,6 3,8 2,7)
i have done something alike, but then to fit a different tube in
my ecc99 linestage, has been replaced by 2 xe80cc.
when the 2 halves of the e80cc are used in parrallel, one e80cc is almost the same as one half of the ecc99. So i had to add a tube, and remove the feedback, but did not change any resistors (ra=9k, rk=220, ck=100uF)
sound is much more nice with these SQ tubes (lot more detail, open sound, ecc99 seems dark sounded compared to these)
i have to recalculate the nfb because open loop amplification has changed, but......
i think i prefer no NFB, and just be gentle with the volume pot 😀
when you would not change the resistors to half their value, the transfer curve will be different, but S and Ri will remain the same....+ there will be more current through rk, ra eg. bigger wattage needed
There will also be more current when you do half the resistors(best option!) but because resistance is less, wattage stays the same.
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