Forum: Vacuum Tubes
December 10th 16, 03:36 PM
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Replies: 41
Views: 7,160
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Forum: Vacuum Tubes
December 9th 16, 11:29 AM
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Replies: 41
Views: 7,160
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Forum: Vacuum Tubes
November 8th 16, 08:50 PM
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Replies: 6
Views: 2,438
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Forum: Vacuum Tubes
October 9th 16, 09:15 AM
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Replies: 4
Views: 2,017
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Forum: Vacuum Tubes
February 26th 16, 01:21 AM
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Replies: 15
Views: 5,321
Patrick is correct, we don’t see many audio...
Patrick is correct, we don’t see many audio amplifiers making use of the 6U8. However, I did not have to look far to find one. It is one of Patrick’s very own early efforts. It has two 6U8s. The...
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Forum: Vacuum Tubes
February 4th 16, 02:43 PM
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Replies: 15
Views: 5,321
Biggest problems with pentodes overall is the...
Biggest problems with pentodes overall is the nonlinearity. It's great
for mixer stages, great for frequency synth in radios, great for IF with
AGC, not so good for audio amplification. Basically,...
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Forum: Vacuum Tubes
February 3rd 16, 04:03 PM
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Replies: 2
Views: 2,509
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Forum: Vacuum Tubes
February 2nd 16, 10:03 PM
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Replies: 15
Views: 5,321
Biggest problems with pentodes overall is the...
Biggest problems with pentodes overall is the nonlinearity. .
I'm not a fan of using them in AF circuitry. A dual triode typically
gives you as much open loop amplification using 2 stages,...
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Forum: Vacuum Tubes
February 2nd 16, 09:50 PM
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Replies: 14
Views: 3,992
Go back & look at the cct carefully. It is a...
Go back & look at the cct carefully. It is a harmonic generator, meant for guitar or other music instruments effects. Then into the main amp. The harmonics are even order 2nd, 4th, 6th & so on. Not...
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Forum: Vacuum Tubes
February 2nd 16, 12:37 PM
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Replies: 14
Views: 3,992
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Forum: Vacuum Tubes
February 2nd 16, 11:37 AM
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Replies: 14
Views: 3,992
probably - it's something I'd want to do...
probably - it's something I'd want to do [again].
looking for output transformers, ran across THIS one.
https://www.amplifiedparts.com/products/P-T125A
it's a 3W somewhat-universal output...
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Forum: Vacuum Tubes
February 1st 16, 06:10 PM
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Replies: 15
Views: 5,321
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Forum: Vacuum Tubes
January 31st 16, 10:54 PM
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Replies: 15
Views: 5,321
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Forum: Vacuum Tubes
January 31st 16, 09:56 PM
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Replies: 15
Views: 5,321
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Forum: Vacuum Tubes
January 31st 16, 06:15 PM
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Replies: 15
Views: 5,321
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Forum: Vacuum Tubes
January 31st 16, 05:26 PM
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Replies: 15
Views: 5,321
Pentode Screen Resistance (rs) Estimation Example
John L Stewart Jan 2016
In the Heathkit UA-1 12W Amplifier we see a 0.1 microF capacitor bypassing a one Meg resistor supplying the screen current. We might think that we can simply take that RC...
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Forum: Vacuum Tubes
December 14th 15, 01:57 PM
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Replies: 4
Views: 2,628
Thanx for your response Peter but it is an air...
Thanx for your response Peter but it is an air cored cross over choke, not a transformer. And the copper band is a right angles to the winding so that coupling would be at a minimum.
We do see...
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Forum: Vacuum Tubes
December 8th 15, 09:31 AM
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Replies: 4
Views: 2,628
Copper Band in a Cross-Over Choke??
What measurable benefit might this copper band have? There is what looks like a connexion to go to ground.
Audiophools bad dream or something new?? Anybody got any ideas??
Cheers to all, John L...
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Forum: Vacuum Tubes
November 27th 15, 07:42 PM
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Replies: 6
Views: 2,822
Keep on motivating Patrick. I've noticed rigor...
Keep on motivating Patrick. I've noticed rigor mortis sets in early in folks around me who sit back & take it easy. I've never had a 10K km year on the bike but I've done a couple of 8K km & quite a...
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Forum: Vacuum Tubes
November 23rd 15, 10:33 PM
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Replies: 2
Views: 2,509
Simple PP Amp with +ve & -ve FB
John Stewart Nov 2015
This circuit is based on an amplifier I built for a friend to be used with a guitar & mike. The date on the schematic is Dec 7, 1958, almost 57 years ago. The entire project...
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Forum: About this forum
November 18th 15, 05:57 PM
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Replies: 1
Views: 34,764
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Forum: Vacuum Tubes
July 8th 15, 09:17 AM
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Replies: 5
Views: 2,441
The e80cc is neither a 12AU7 or 12AX7. See it...
The e80cc is neither a 12AU7 or 12AX7. See it here-
http://frank.pocnet.net/sheets/190/e/E80CC.pdf
& here-
http://frank.pocnet.net/sheets/009/e/E80CC.pdf
It is spec’d for digital applications,...
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Forum: Vacuum Tubes
May 31st 15, 10:38 PM
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Replies: 5
Views: 3,951
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Forum: Vacuum Tubes
May 18th 15, 02:30 PM
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Replies: 5
Views: 3,951
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Forum: Vacuum Tubes
December 13th 14, 01:30 AM
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Replies: 6
Views: 6,585
Here is confirmation of Patrick T's comment on...
Here is confirmation of Patrick T's comment on our ability to hear phase. Copied from Fred E Terman's Electronic & Radio Engineering, 4th Edition.
A very good reference text for anyone involved in...
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