Search found 997 matches
- Sun Jan 22, 2012 12:01 pm
- Forum: Everyones Projects
- Topic: j-FET / Triode Phono front-end
- Replies: 287
- Views: 174813
I've been looking at the folded cascode design on jc's blog and I have drawn what I think is the thing from a conceptual perspective to bring out the nature of the folded cascode and show how it differs from a standard cascode... I hope I have it right :? In a standard cascode the bottom device curr...
- Fri Jan 20, 2012 8:45 pm
- Forum: Assorted Stuff
- Topic: next owston meet?
- Replies: 17
- Views: 6472
- Fri Jan 20, 2012 8:20 am
- Forum: Everyones Projects
- Topic: j-FET / Triode Phono front-end
- Replies: 287
- Views: 174813
- Thu Jan 19, 2012 9:02 pm
- Forum: Everyones Projects
- Topic: j-FET / Triode Phono front-end
- Replies: 287
- Views: 174813
- Wed Jan 18, 2012 9:04 am
- Forum: Everyones Projects
- Topic: j-FET / Triode Phono front-end
- Replies: 287
- Views: 174813
- Mon Jan 16, 2012 9:03 pm
- Forum: Everyones Projects
- Topic: Changing 300B driver, possibly to C3M
- Replies: 14
- Views: 14461
Hello Ian, It is a general rule for pentodes that screen current is 20-25% of anode current with beam plate tetrodes being closer to 25% and true pentodes being closer to 20% for normal operating conditions... Their are some exceptions like the EF86 (17%). C3g is a nice driver for DHTs but it is sta...
- Mon Jan 16, 2012 2:02 pm
- Forum: Everyones Projects
- Topic: Changing 300B driver, possibly to C3M
- Replies: 14
- Views: 14461
Normally g2 current is 20% to 25% of Ia so for 20mA anode current design for 4mA g2 current as C3m are at the 20% end of the spectrum... If you are using a potential divider to fix g2 voltage then you need some current for the bottom resistor and so the 10mA for the g2 chain is not unreasonable... N...
- Sun Jan 15, 2012 9:35 pm
- Forum: Everyones Projects
- Topic: 2A3 Monoblocks
- Replies: 400
- Views: 119876
The point about the error amp for the shunt reg is that it acts to supplement the Gm for the shunt valve i.e. it makes it act as if it had much more Gm - typically the error amp gain times the Gm of the shunt valve so its easy to make your 6L6 act as if it had a Gm of 100mA/V or more... Pauls remark...
- Sat Jan 14, 2012 11:25 am
- Forum: Everyones Projects
- Topic: 2A3 Monoblocks
- Replies: 400
- Views: 119876
Not to put any pressure on you and just for interest here is a page from Tubecad about shunt regulators http://www.tubecad.com/2011/08/blog0209.htm and at the bottom he shows a tube shunt reg with error amp using 12DW7 with a performance curve. He also discusses the benefits and drawbacks of using a...
- Tue Jan 10, 2012 9:36 pm
- Forum: Everyones Projects
- Topic: 2A3 Monoblocks
- Replies: 400
- Views: 119876
I've no more space on the top deck for another valve Well that's easy - replace the 6AU6 with a dual pentode! There are several see http://www.mif.pg.gda.pl/cgi-bin/vs4.pl Damn! Search doesn't work but a search on tubedata for double pentodes yields lots of the beasties! Honest!!! or take the easy ...
- Tue Jan 10, 2012 11:05 am
- Forum: Everyones Projects
- Topic: 2A3 Monoblocks
- Replies: 400
- Views: 119876
- Fri Dec 30, 2011 8:38 pm
- Forum: Valves
- Topic: SRPP Series Shunt Reg Anyone?
- Replies: 56
- Views: 22788
Previously I designed the attached psu for Dave Dove's RIAA amp using a TV dual triode :D It would have been better with a VR ref in their somewhere on the shunt but not sure that a 75V VR tube would work at these B+ volts... and , following this discussion the BG should come out! This is a fantasti...
- Fri Dec 30, 2011 3:41 pm
- Forum: Everyones Projects
- Topic: 300B enjoys a good thrashing from 6C45
- Replies: 108
- Views: 43855
- Tue Dec 27, 2011 9:45 pm
- Forum: Valves
- Topic: 6B4G testing...
- Replies: 3
- Views: 3937
If you find a copy of the RCA datasheet such as http://www.hifitubes.nl/weblog/index.php/rca-2a3-datasheet/ then the spec is 5250uohms for transconductance but really that is nothing more than a number on a spec sheet :lol: If you look at page 4 of the same pdf then you see the transconductance curv...
- Tue Dec 27, 2011 4:33 pm
- Forum: Speakers
- Topic: Quasars AER repair
- Replies: 57
- Views: 30743