Go Back   Home > Forums > >

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Those Magnificent Television Tubes
Those Magnificent Television Tubes
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools
Old 19th October 2020, 06:58 PM   #1311
smoking-amp is offline smoking-amp  United States
diyAudio Member
 
smoking-amp's Avatar
 
Join Date: Dec 2001
Location: Hickory, NC
Oh,
I guess if all the plate outputs are individually AC coupled, then X*X + (-X)*(-X) cross coupling will work. But just using the X*X output alone should be fine here.

(the two BDT tubes over the CCS are used to get the grid 1 functions linearized, otherwise one would get X*(X^3/2) due to non-linearity of grid 1. Some cathode degeneration resistors could also be included for even better linearization here. Or, for extreme linearity, a third BDT could be used in place of the CCS in a split cascode like arrangement, so not using grid 1 control at all then. )

Last edited by smoking-amp; 19th October 2020 at 07:03 PM.
  Reply With Quote
Old 19th October 2020, 07:50 PM   #1312
Tubelab_com is offline Tubelab_com  United States
diyAudio Member
 
Tubelab_com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
I would also suggest getting some 6197 tubes...
The 6197 is a 6CL6 with a cathode coating formulated for "computer use" where long periods of operation (days) with zero cathode current are possible. I have several hundred of each tube, over a thousand 5686 tubes, and several boxes full of other military surplus and computer tubes from the 50's and early 60's. All are well used and have not seen power since the 1960's.

I did experiment with all of these during the development of my vacuum tube VCA (voltage controlled amplifier). The VCA started with a clone of the famous Fairchild 670 compressor circuit, build with genuine 6386 tubes (real expensive now) from the 1960's as my benchmark. I used the same Edcor transformers in each build to remove that variable from the testing. My vacuum tube VCA works as good as the 670 design, but uses a pair of $1 tubes and a pair of mosfet followers for buffers. The vacuum tube Moog ladder VCF (LPF) is not quite up to Moog specs yet though.

If I were to revisit the squarer circuit with opamps, it would be trivial. We (Motorola) developed a circuit in the early 80's to recover a data stream from the discriminator of an FM radio. We called it a "center slicer" and it used a single stage of an opamp or comparator chip. The raw DC coupled discriminator output fed one input, while the LPF (a few Hz corner) filtered signal fed the other input. The output of the chip is the data stream. The corner frequency of the LPF has to be high enough to track frequency drift between the receiver and the transmitter, but low enough not to follow some pretty slow data (around 100 baud). Max data rate was 2400 to 4800 baud.....it was the 80's and we were using 25 KHz RF channels.
__________________
Tubelab, I blow stuff up so that you don't have to.
  Reply With Quote
Old 6th December 2020, 03:27 AM   #1313
spinch is offline spinch  United Kingdom
diyAudio Member
 
Join Date: Nov 2020
Location: London UK - NW6 7YX
I build valve power amps, and I use non - microphonic EF183 and EF184 in the first stage with excellent results. The EF183's - frame grid varimu - sound a lot better - anyone know why?
  Reply With Quote
Old 6th December 2020, 12:04 PM   #1314
Tubelab_com is offline Tubelab_com  United States
diyAudio Member
 
Tubelab_com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
The variable mu remote cutoff characteristics of the EF183 (6EH7) tend to generate considerable second harmonic distortion. The level of 2H goes up as the signal level increases. Many listeners find this effect pleasing.

I use similar tubes in my variable gain amp. The 6EH7 is one of the possible choices and it is quite cheap. Like the old Fairchild 670, the even order harmonics are reduced by using balanced push pull operation.
__________________
Tubelab, I blow stuff up so that you don't have to.
  Reply With Quote
Old 6th December 2020, 01:12 PM   #1315
Kay Pirinha is offline Kay Pirinha  Germany
diyAudio Member
 
Kay Pirinha's Avatar
 
Join Date: Oct 2011
Location: Somewhere in Germanistan
6EH7 is equivalent to EF183, see:
Click the image to open in full size.
EF183 and 184 are quite cheap tubes here also, as are their Russian equivalents, 6SH51P and 6SH15P.

Best regards!
__________________
"I spent a lot of money on booze, birds and fast cars. The rest I just squandered." (George Best)
  Reply With Quote
Old 7th December 2020, 04:30 PM   #1316
spinch is offline spinch  United Kingdom
diyAudio Member
 
Join Date: Nov 2020
Location: London UK - NW6 7YX
As balanced operation from XLR outputs of many sources (eg.CD players, etc) are already built in, there is no need for additional phase splitters from unbalanced RCA sources-it's already done for you. So I use two EF183's each driven from their two XLR outputs in a fully balanced p/p arrangement driving a p/p output pair of EL34's - thus completely minimising even harmonic distortion.
  Reply to this post

Reply


Those Magnificent Television TubesHide this!Advertise here!
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
MOAK: The Mother of All Karlsonators (aka The Magnificent Monster) DeonC Subwoofers 126 23rd January 2015 04:35 PM
Television question... toptip Everything Else 6 23rd October 2012 07:50 PM
Surround sound amp, Sub woofer and television warrennyc Subwoofers 4 3rd January 2005 11:33 AM
distance from television ALFIrE Multi-Way 2 30th March 2004 07:46 AM
Television broken Bull Everything Else 3 21st January 2003 01:08 AM


New To Site? Need Help?

All times are GMT. The time now is 08:59 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki