Thats what I thought.... Is that what happens in practice..
Perhaps I should say set to 200mA with both heaters and switch one out does it go down?
Perhaps a T03 package may be better.. using mica and compound..
Regards
M. Gregg
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I´ve been messing around with it so much that it´s time to fix the layout.
New mozeners with easily exchangeble zenerref.
Better placed mosfets for drive so it´s easy to change gridstoppers.
My last mosfet blowup arced over into topplate and killed one of the drive mosfets.
Í think your right time for mica/compound i usually avoid it because it´s messy when tweaking around and the softpads do the job most of the time.
And ABSOLUTELY NO MORE OTL DISIPATION DRAGRACING !!!!!
Hmmm wonder how a redplating 6c33c looks
New mozeners with easily exchangeble zenerref.
Better placed mosfets for drive so it´s easy to change gridstoppers.
My last mosfet blowup arced over into topplate and killed one of the drive mosfets.
Í think your right time for mica/compound i usually avoid it because it´s messy when tweaking around and the softpads do the job most of the time.
And ABSOLUTELY NO MORE OTL DISIPATION DRAGRACING !!!!!
Hmmm wonder how a redplating 6c33c looks
Depends on what the Threshold-Voltage of the 'Mozener' is set to via its pot and diode....
If below the bias-volts, then it will conduct, if above, will appear as O/C and act as a Clamp at whatever voltage the diode and pot are set up to....
Mozener....
When I first saw that word, I thought you were talking about a person!
Hey--We writing our own Language now!
What size cap are we talking about?....
Have you worked out how you are going to keep the heat under control?
Regards
M. Gregg
Depends on what the Threshold-Voltage of the 'Mozener' is set to via its pot and diode....
If below the bias-volts, then it will conduct, if above, will appear as O/C and act as a Clamp at whatever voltage the diode and pot are set up to....
Mozener....
When I first saw that word, I thought you were talking about a person!
Hey--We writing our own Language now!
Well very shortly when the lager comes out I guess I will create even more words....most poeple will not understand...
You know what they say if you don't come out of the Pub talking rubbish you haven't had a good night...LOL
Have you ever been the driver <<<no beer allowed and wondered what everyone is laughing about....cuz it don't make sense...well its at the driver who aint had a drink...LOL
Catch you laters.......have a good time....if not get legless anyway at least no one can laugh at you....
Regards
M. Gregg
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Small cap for stabilizing not crirical.
Amp is apart rearanging the sand on nice mica washers/paste.
PI back to 18K measures better.
New nice Holco resistors for PI and finals.
It´s early cristmas today in my hunt for resistors i came across an old assortment of what i thought was CF but it turned out to be CC made by ISKRA in Slovakia a complete set of 25pcs each value E24
So now it has CC at required places.
And as stated earlíer it will be ABSOLUTELY NO MORE DISIPATION DRAGRACING it kills the sand
Question is who will be first to hit the livingroom Santa or the OTL ???
Small cap for stabilizing not crirical.
Amp is apart rearanging the sand on nice mica washers/paste.
PI back to 18K measures better.
New nice Holco resistors for PI and finals.
It´s early cristmas today in my hunt for resistors i came across an old assortment of what i thought was CF but it turned out to be CC made by ISKRA in Slovakia a complete set of 25pcs each value E24
So now it has CC at required places.
And as stated earlíer it will be ABSOLUTELY NO MORE DISIPATION DRAGRACING it kills the sand
Question is who will be first to hit the livingroom Santa or the OTL ???
What will be your final bias current on one and two heaters?
How many watts have you got per channel now?
I just thought if I wanted to try fixed bias then I could use a 3 or 6VA power Tx in reverse 9V in and 110-110V using the existing 6V ac heater winding to supply the 9V in I would get about 80V out X2 and the two 110V windings would give me two isolated bias supplies...
However I want to play with the mozener settings first just curious about what power out we would get with 160V rails (fixed bias) I guess 25Watt double heater and ~12W single heater..the standard O/P..
Regards
M. Gregg
For fixed bias you could use a devider from one of the rails and ad a small second transformer.
I managed to squeze out 10w at 0.32 THD and i still have issues.
I´ve been shifting around resistor so right now it´s misbehaving again (oscilation)
Santa won the race to the livingroom kids are harvesting the gifts as we speak.
I managed to squeze out 10w at 0.32 THD and i still have issues.
I´ve been shifting around resistor so right now it´s misbehaving again (oscilation)
Santa won the race to the livingroom kids are harvesting the gifts as we speak.
I must admit that my speakers play quite loud and I don't get oscillation..
And it does sound good!
Can't think why you have the instability..
I will probably try fixed bias curiosity has the best of me...
Its playing as I type this....Try a 1K in the first CCS gate stopper...
At the moment its staying as is until after Xmas..
Hope you have a great day....
Looking forward to more progress... I'm under pressure from the other half...things to do..LOL
Regards
M. Gregg
It´s playing well when not terrorised by the resistorswitcher
Haven´t we agreed on that fixed bias is CHEATING
Servoassisted autoadjustingbias you can probably get away with (you´ll be on probation for a while to see if your let back in the club)
Looking forward to your progress.
This is now tested and verified:
18k for PI gives less distorsion instead of 47k
1k/270 is enough gain.
I´m running 350mA right now it´s not efficient but they do sound better to my ear.
If i wanted efficiency i´d by a class-d amp
Haven´t we agreed on that fixed bias is CHEATING
Servoassisted autoadjustingbias you can probably get away with (you´ll be on probation for a while to see if your let back in the club)
Looking forward to your progress.
This is now tested and verified:
18k for PI gives less distorsion instead of 47k
1k/270 is enough gain.
I´m running 350mA right now it´s not efficient but they do sound better to my ear.
If i wanted efficiency i´d by a class-d amp
So i now stopped messing around and settled for 300ma.
this gives over 1%thd at full OP but my chinese sockets aren´t made as the originals so i don´t dare to push it harder.
My ears like them better with some current.
Can always go half power with one filament.
It runs very nicely pure class A to ~3w outperforming what i got here at home.
When at full throttle it´s not the filharmonics performing anyway.
I´ll let it play for a few days and if it lives after that it´s final assembly.
Is it powerconsumtion/heat that makes people settle for less current ??
this gives over 1%thd at full OP but my chinese sockets aren´t made as the originals so i don´t dare to push it harder.
My ears like them better with some current.
Can always go half power with one filament.
It runs very nicely pure class A to ~3w outperforming what i got here at home.
When at full throttle it´s not the filharmonics performing anyway
.I´ll let it play for a few days and if it lives after that it´s final assembly.
Is it powerconsumtion/heat that makes people settle for less current ??
Why fixed bias is cheating ? You will shorten the life of the output tubes with high dissipation , ( like 30W or over ) trying to get more power , you are "cheating " the amp by doing that , and its better to make it with another way . BTW no one tell us what is the output impedance of the amp ? I know its high but how ?Higher B+- is on the list for next version including a bigger chassi.
Specs say 250 is ok for dissipation over 30w.
I have some industrial stepdown toroids 400-240 run it backwards some nice chokes and the recipe says +-250.
Fixed bias is cheating.
Just a joke
Fixed is the common way.
This has been an experiment in different aproaches of OTL.
I´ve now been running it:
Katod bias ~5w
Mozener bias ~10w
Fixed bias ~20w
Mixed bias ~14w
The appealing with non fixed bias is the plug and play concept.
Its ok with the joke , as for the amp sorry but I don't get it right , how much power you get now and what is the dissipation power for the output tubes ? , and what kind of bias you use now ? .
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