Cool. How does it sim with EL34 or 6V6 tubes too? I love all 3 tubes, so if the 6L6 stands taller than the rest and wins the crossing curve challenge, so be it.
EDIT: BTW, How did you know that I have a quad of NOS Amperex Holland 6DJ8s obtained from JRB with his Aikido 24V kit?
With 6L6 you have smooth AB crossing without Schottkys.
Read O.H.Schade "Beam Power Tubes", (specifically 6L6).
Look midpage in RCA section. Tube Data
But 6L6 will probably still want error amp. MOSFET skates
out need for error amp cause it has such ridiculously high
transconductance compared to a Pentode.
You could slap a monster stack of Schottkys under almost
any Pentode and fake a pretty good square law crossing.
But 6L6 was designed for ideal Square Law, from get-go...
If you have the differential error amp, smoothness of AB
crossing is less an issue. You won't have sudden handoff
of control from one Class A triode to the other.
Read O.H.Schade "Beam Power Tubes", (specifically 6L6).
Look midpage in RCA section. Tube Data
But 6L6 will probably still want error amp. MOSFET skates
out need for error amp cause it has such ridiculously high
transconductance compared to a Pentode.
You could slap a monster stack of Schottkys under almost
any Pentode and fake a pretty good square law crossing.
But 6L6 was designed for ideal Square Law, from get-go...
If you have the differential error amp, smoothness of AB
crossing is less an issue. You won't have sudden handoff
of control from one Class A triode to the other.
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Alrighty guys, I'm coming back to this. I will remove the 10W OPT cap if I can just use the little guys for initial testing before ordering much bigger iron. I must admit I've been seduced by the thought of 56W of triode-inspired pentode power. 😛
But a new question. I have access to nice shunted PS boards capable of delivering about 90mA into 300-325V rails. Far more voltage than I need for this amp or want to run for that matter as I plan to use MWT 6V6 or the 6L6 tubes.
But the newbie virus strikes again. Using the Yundt schematic from my post #46, does it lend itself to split rail voltages? I remember ken or smoking-amp noting it needed negative voltages.
ken, can your tweaked version be run off a split rail supply? Supply +/-190Vdc instead of +380V?
I have three of these PS boards available so I could even have the input tubes on a different voltage. The plan was to put four of the outputs on one supply each and all of the input tubes on the third. That's about 275-300mA of available current. If it will need more current than 100mA per output per side, then I'll have to go back to a tube rectified supply and do the negative supply separately.
Thanks again guys
But a new question. I have access to nice shunted PS boards capable of delivering about 90mA into 300-325V rails. Far more voltage than I need for this amp or want to run for that matter as I plan to use MWT 6V6 or the 6L6 tubes.
But the newbie virus strikes again. Using the Yundt schematic from my post #46, does it lend itself to split rail voltages? I remember ken or smoking-amp noting it needed negative voltages.
ken, can your tweaked version be run off a split rail supply? Supply +/-190Vdc instead of +380V?
I have three of these PS boards available so I could even have the input tubes on a different voltage. The plan was to put four of the outputs on one supply each and all of the input tubes on the third. That's about 275-300mA of available current. If it will need more current than 100mA per output per side, then I'll have to go back to a tube rectified supply and do the negative supply separately.
Thanks again guys
I've been away from this thread too long and completely lost my train of thought.
Which tweaked version specifically? I presented more than a few half-bakes.
Which tweaked version specifically? I presented more than a few half-bakes.
Alrighty, I've been chugging away at this slowly, but I've decided to remove the 10W cap. Might as well build it right the first time.
I think I'm going to make it a Decicode! I'm still going to use the MWT 6V6GTs for the triode tubes, but now I'm going to use 7591s for the power pentodes since they have higher transconductance and are easier to drive. I'm seriously considering paralleling them too for more output power.
I'm sure some values will get tweaked, but I need to decide on the signal tubes. Leaning more towards 12BH7s or 6CG7/6FQ7 or the 12V equivalents. I'm also going to build JC Morrison's hybrid PS for it and just keep paralleling 5AR4s to hit the current I need.
What I'm still working on is to see if I can incorporate Decware's concepts of VR tubes on the grids (at least in the signal side) and Decware's Lucid mode feedback off the secondaries of the OPTs.
Right now it looks like SumR can only do 50W max OPTs, but I think paralleled 7591s on each side will provide more power than that. E-P iron is nice, but Jack's prices for high wattage OPTs is steep and Japanese iron becomes competitive over 50W. Sigh, I need to see how much Edcor will charge then decide on the iron.
But, it's moving forward slowly, so thanks again guys.
I think I'm going to make it a Decicode! I'm still going to use the MWT 6V6GTs for the triode tubes, but now I'm going to use 7591s for the power pentodes since they have higher transconductance and are easier to drive. I'm seriously considering paralleling them too for more output power.
I'm sure some values will get tweaked, but I need to decide on the signal tubes. Leaning more towards 12BH7s or 6CG7/6FQ7 or the 12V equivalents. I'm also going to build JC Morrison's hybrid PS for it and just keep paralleling 5AR4s to hit the current I need.
What I'm still working on is to see if I can incorporate Decware's concepts of VR tubes on the grids (at least in the signal side) and Decware's Lucid mode feedback off the secondaries of the OPTs.
Right now it looks like SumR can only do 50W max OPTs, but I think paralleled 7591s on each side will provide more power than that. E-P iron is nice, but Jack's prices for high wattage OPTs is steep and Japanese iron becomes competitive over 50W. Sigh, I need to see how much Edcor will charge then decide on the iron.
But, it's moving forward slowly, so thanks again guys.
Not sure what version you are referencing now. Schematic?
Decware's "Lucid Mode" looks rather like Cuckoo mode to me, wasting half the power and collapsing the stereo image with a power resistor between the two channel outputs:
DECWARE / Zen TABOO Classic Single Ended tube amplifier
Decware's "Lucid Mode" looks rather like Cuckoo mode to me, wasting half the power and collapsing the stereo image with a power resistor between the two channel outputs:
DECWARE / Zen TABOO Classic Single Ended tube amplifier
Thanks.
The modded Yundt schematic. I haven't modded anything yet. I haven't had time to mess with tweaking the original or Ken's schematic to suit my needs. I'll post a modded schematic once I have the chance to mess with it over the holidays. I'm pretty slammed right up to Christmas Eve and with the kids out of school, nothing gets done during lunch hours...
I plan to test the Decware Lucid mode on a Tubelab Prototyping system. It may not even work in P-P. I found it intriguing and a friend who heard the Taboo with headphones attached directly to the speaker outputs rather enjoyed it.
The modded Yundt schematic. I haven't modded anything yet. I haven't had time to mess with tweaking the original or Ken's schematic to suit my needs. I'll post a modded schematic once I have the chance to mess with it over the holidays. I'm pretty slammed right up to Christmas Eve and with the kids out of school, nothing gets done during lunch hours...
I plan to test the Decware Lucid mode on a Tubelab Prototyping system. It may not even work in P-P. I found it intriguing and a friend who heard the Taboo with headphones attached directly to the speaker outputs rather enjoyed it.
I prototyped it nonetheless but with different tubes:
6n16b for input and splitter
triode connected 6ee5p for the power triodes
6p1p for the power pentodes
6n1p for the corrective amp.
Other than discussed in this Stone old thread, sorry for that ... it works using Van Doorn's original idea as published in his paper.
