Search found 26 matches
- Sun Aug 23, 2009 4:18 pm
- Forum: Inductors
- Topic: small 49% nickel chokes
- Replies: 3
- Views: 7388
high cdr plate choke
hi dave, thanks for the 1:2 autoformers i got on last monday ;-) i am already working on a 2-stage amplifier design and i would like to implement a high dcr plate choke for biasing and direct coupling reasons. Do you think a plate choke of 35H at 15 mADC could be wound in order to have a DCR of 4000...
- Sun Jul 19, 2009 10:30 am
- Forum: Transformers
- Topic: 8K:8R 49% nickel outputs for a pentode.
- Replies: 13
- Views: 10598
hi dave, just to give you news about that pair of opt's done for 6e5p. amp is using only one 6e5p per channel with unusual biasing method, gives 1W+ in triode and almost 2.5W in pentode. sound gorgeous either pentode or triode connected (selected by switch) ! extremely live sound with plenty of micr...
- Sat May 16, 2009 2:03 pm
- Forum: Transformers
- Topic: power output se transformer as input transformer
- Replies: 1
- Views: 3904
power output se transformer as input transformer
hi all, i had some weeks ago the idea to use tube amplifier output s.e. transformers as step up input transformers connected in reverse, to get real input voltage swing and no bandwidth limitation. you need to correctly load the output winding to reflect an acceptable load to the source. that way on...
- Mon Apr 13, 2009 4:36 pm
- Forum: Transformers
- Topic: 8K:8R 49% nickel outputs for a pentode.
- Replies: 13
- Views: 10598
- Mon Apr 13, 2009 8:55 am
- Forum: Transformers
- Topic: 8K:8R 49% nickel outputs for a pentode.
- Replies: 13
- Views: 10598
- Sun Apr 12, 2009 11:47 am
- Forum: Transformers
- Topic: 8K:8R 49% nickel outputs for a pentode.
- Replies: 13
- Views: 10598
hi dave, thank you for all those explanations. you are absolutely correct regarding lenz's law, thanks for reminding me :oops: the 6e5p will be used at 220V Vpk, -2.4 Vgk, 150V Vg2 and 30mA dc Ip in order to almost get 2.5W out. your tests and figures at 20mA dc Ip clearly show that i should go with...
- Fri Apr 10, 2009 5:34 pm
- Forum: Transformers
- Topic: 8K:8R 49% nickel outputs for a pentode.
- Replies: 13
- Views: 10598
- Tue Apr 07, 2009 7:57 pm
- Forum: Transformers
- Topic: 8K:8R 49% nickel outputs for a pentode.
- Replies: 13
- Views: 10598
- Sat Apr 04, 2009 11:11 am
- Forum: Transformers
- Topic: 8K:8R 49% nickel outputs for a pentode.
- Replies: 13
- Views: 10598
- Wed Feb 04, 2009 7:35 am
- Forum: Transformers
- Topic: tapped grid choke as input step-up autoformer
- Replies: 6
- Views: 6937
- Sun Feb 01, 2009 4:17 pm
- Forum: Transformers
- Topic: tapped grid choke as input step-up autoformer
- Replies: 6
- Views: 6937
hi dave, thanks for the explanation, sounds clear to me now. further to your explanations, i have a question regarding the avc connection. do you think that an avc like yours (i do like them as they sound extremely good on my system) could be used reverse connected ? i mean does it make sense to use...
- Mon Jan 05, 2009 11:59 pm
- Forum: Transformers
- Topic: tapped grid choke as input step-up autoformer
- Replies: 6
- Views: 6937
hi dave, thanks for your reply, and happy new year 2009 ! would the troubles come from the grid choke itself or from the fact it would be tapped ? i can understand that such high inductance values could give some headaches to sources ... what would you suggest as an input autoformer with 1:2 step-up...
- Mon Dec 29, 2008 3:06 am
- Forum: Transformers
- Topic: tapped grid choke as input step-up autoformer
- Replies: 6
- Views: 6937
tapped grid choke as input step-up autoformer
hi dave, i have been thinking in using a grid choke instead of the usual grid resistor as an input load in my new single tube se amp. the tube would need to be biased at -6v between grid and cathode so i was wondering whether a grid choke could be tapped in order to give some gain to the stage like ...
- Wed Nov 26, 2008 11:55 am
- Forum: Transformers
- Topic: differential parafeed PP amp with 1:1 bifilar plate chokes
- Replies: 2
- Views: 6282
- Mon Sep 08, 2008 8:53 am
- Forum: Transformers
- Topic: differential parafeed PP amp with 1:1 bifilar plate chokes
- Replies: 2
- Views: 6282
differential parafeed PP amp with 1:1 bifilar plate chokes
good morning, i have been in touch with dave about 1:1 bifilar plate choke (bpc) and parafeed output stage without coupling capacitor to opt. i am about to make some tests with the very nice bpc's i purchased and received from dave, with a simple circuit using only one tube for one watt. however it ...
- Tue Sep 02, 2008 6:16 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
hi steve and dave, it appears that if we closely look at a parafeed output stage using a 1:1 bifilar plate choke direct feeding an opt, the last psu cap still remains in the audio signal path. if we admit the opt connected to the choke reflects a constant impedance across its primary winding, the lo...
- Wed Aug 27, 2008 7:11 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
hi dave, thank you for your comments. i sent a private e-mail to you regarding purchase of a pair of chokes. regarding the 5902 specs, there must be a printing error with the rp value. i have several data sheets of 5902 tube and all state 15,000 ohms. but it is not a problem according to your measur...
- Wed Aug 27, 2008 6:21 am
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
hi dave, thank you for the new measurements. i have to say that the behaviour of the 1:1 bifilar plate choke is pretty impressive all over the audio range whatever the DCR and the load impedance. i am curious to see what happens with a 100 / 150 DCR choke as the L seems to change a bit around the 30...
- Tue Aug 26, 2008 5:24 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
hi dave, thank you for all those measurements. as far as i have understood, it appears that the frequency response vs. load remains quite constant up to 100kHz and easily goes down to 40Hz whatever the opt primary reflected impedance connected to the 1:1 bifilar plate choke. is it correct ? one ques...
- Mon Aug 25, 2008 4:56 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
- Sun Aug 24, 2008 5:14 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
hi dave, thank you for your post and your e-mail. the options described in your post will be discussed with my friends, all sound very good to me. by the way the idea of 49% nickel output autoformer for bass amp is highly appealing, we will talk about that later on. regarding full range 1:1 bifilar,...
- Fri Aug 22, 2008 4:16 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
hi dave, thank you for your post. i sent a private e-mail to you, feel free to reply to my private address. there are some changes regarding the 1W amplifier project and you will like it :D we have decided to separate bass and mid-high for bi-amping therefore i will work on two amplifiers using 1:1 ...
- Thu Aug 21, 2008 4:15 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
Hi Dave, Thank you for your quick and extremely detailed reply. The idea i would like to go further with is not that far from the one tried and enjoyed by the Colorado guys. The current amplifier is using a Sowter 50% mumetal 50% M6 grade core gapless opt with a 3K primary coupled to a high quality ...
- Thu Aug 21, 2008 11:53 am
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
- Wed Aug 20, 2008 6:08 am
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
hi, sorry to disturb again but i would appreciate if somebody could draw a simple parafeed tube stage using bifilar plate choke and post it on the forum for everybody use. thanks a lot. i have been using a tiny parafeed single stage pentode amplifier as full range amp with duelund coupling cap (extr...
- Tue Aug 19, 2008 5:13 pm
- Forum: Transformers
- Topic: 1:1 bifilar output to remove the parafeed coupling cap.
- Replies: 31
- Views: 37037
1:1 bifilar output to remove the parafeed coupling cap
hi, this my first post to the forum, extremely interesting, thanks to dave and to the all of you. i have been reading and reading again about the 1:1 bifilar plate choke as 1:1 output transformer without need of parafeed coupling cap but i can't understand how it works. sorry not to understand but i...