Modeling 6B4G?
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Modeling 6B4G?
by Ty_Bower » Sun Apr 12, 2009 9:36 am
Does anyone have a mathematical equation suitable for modeling the plate curves of a 6B4G?
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
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by Brik » Sun Apr 12, 2009 3:22 pm
Hi Ty,
I suppose a Spice model of 2A3 might do the trick?
"Andrei" at diyAudio Forums posted a library of models including one for 2A3.
http://www.diyaudio.com/forums/attachme ... 1139538713
The post is at:
http://www.diyaudio.com/forums/showthre ... adid=73461
I have been meaning to port it to Circuit Maker, but I haven't gotten a "round tuit".
I suppose a Spice model of 2A3 might do the trick?
"Andrei" at diyAudio Forums posted a library of models including one for 2A3.
http://www.diyaudio.com/forums/attachme ... 1139538713
The post is at:
http://www.diyaudio.com/forums/showthre ... adid=73461
I have been meaning to port it to Circuit Maker, but I haven't gotten a "round tuit".
/b
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by Ty_Bower » Sun Apr 12, 2009 7:01 pm
Thanks. I'll take a look at those.
Has anyone ever wondered if the Get*Set*Go drives the 6B4G a little hard? The textbook RCA recipe calls for 250 volts plate, 750 ohm cathode resistance, and 60 mA idle current. That puts idle dissipation right around 12 watts on a tube with a 15 watt maximum.
The G*S*G runs it at 308 volts plate with 900 ohms cathode resistance, for a total of ~56 mA idle current and 14.5 watts idle dissipation. I'm trying to decide if this is something I ought to try to tinker before I start building, or just not worry about it...
Has anyone ever wondered if the Get*Set*Go drives the 6B4G a little hard? The textbook RCA recipe calls for 250 volts plate, 750 ohm cathode resistance, and 60 mA idle current. That puts idle dissipation right around 12 watts on a tube with a 15 watt maximum.
The G*S*G runs it at 308 volts plate with 900 ohms cathode resistance, for a total of ~56 mA idle current and 14.5 watts idle dissipation. I'm trying to decide if this is something I ought to try to tinker before I start building, or just not worry about it...
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
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Ty_Bower - KT88
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by EWBrown » Mon Apr 13, 2009 7:00 am
THe "250 Volt" rating for the 6B4G is the voltage difference between the plate and the filament / cathode. (V P-K) With the 305V on the plate, and the "cathode" sitting at around 50 to 55V, the ratings aren't being excessively "stretched". There is also a few volt's drop from the two "center tap" resistors, s there is a tad more safety margin.
The "classic" RCA tube manual design runs the 2A3 (and 6B4G) at 250V P-K with 60 mA plate current, just "nailing the" 15 watt PD rating. I'm sure, that in real-life situations, this often got exceeded by 5-10%, with no ill efects.
Newer imported СДЕЛАНО В СССР . Sovtek, E-H, J/J, etc single-plate 6B4Gs, 2A3s, etc, can take higher voltage and current than the vintage/classic/NOS tubes. Treat the old ones more gently, as they are expensive and getting harder to replace, the Sovteks, J/Js, etc are reasonably priced and readily available. The 1950s vintage Russian Svetlana dual plate 6C4C (6S4S) and 2C4C (2S4S) are more delicate.
These have the classic twin plate construction.
Zey vork wery vell in Tupelov TU-4 samolyet, tovarisch, sank you for the ze werry nice B-29s.
(how's that for bastardized Russlish...)
/ed B
The "classic" RCA tube manual design runs the 2A3 (and 6B4G) at 250V P-K with 60 mA plate current, just "nailing the" 15 watt PD rating. I'm sure, that in real-life situations, this often got exceeded by 5-10%, with no ill efects.
Newer imported СДЕЛАНО В СССР . Sovtek, E-H, J/J, etc single-plate 6B4Gs, 2A3s, etc, can take higher voltage and current than the vintage/classic/NOS tubes. Treat the old ones more gently, as they are expensive and getting harder to replace, the Sovteks, J/Js, etc are reasonably priced and readily available. The 1950s vintage Russian Svetlana dual plate 6C4C (6S4S) and 2C4C (2S4S) are more delicate.
These have the classic twin plate construction.
Zey vork wery vell in Tupelov TU-4 samolyet, tovarisch, sank you for the ze werry nice B-29s.
(how's that for bastardized Russlish...)
/ed B
Last edited by EWBrown on Thu Apr 30, 2009 8:39 am, edited 3 times in total.
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by Shannon Parks » Tue Apr 14, 2009 5:53 am
1) During the testing and prototyping phase the Sovtek 6B4G didn't want to see lower voltages than that! Their distortion would really drop off a cliff. So the B+ ended up being a 'magic zone' actually - within the upper limit of old stock 6B4Gs and the lower limit of the new Sovtek tubes. Interesting, huh?
2) I seem to recall some of the later RCA datasheets also spec'd the 6B4G at 275V or 300V.
2) I seem to recall some of the later RCA datasheets also spec'd the 6B4G at 275V or 300V.
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