new English made ECC81/82/83 types!?

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new English made ECC81/82/83 types!?

Postby dai h. » Mon Sep 08, 2008 6:30 pm

http://www.techtubevalves.com

and check out the video!

The Blackburn Story (Mullard factory)

(approx. half an hour in length)

http://www.techtubevalves.com/about_us/film_reels.php
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Re: new English made ECC81/82/83 types!?

Postby Brian Wallace » Mon Sep 08, 2008 8:03 pm

Dai,

What's going on internally in these tubes and what will they cost?
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Re: new English made ECC81/82/83 types!?

Postby dai h. » Mon Sep 08, 2008 8:13 pm

hey Brian,

sorry I have no other info other than what you can see on that site. There is a datasheet for the e813cc provided:

http://www.techtubevalves.com/valves/e8 ... asheet.pdf

plate structure is interesting. Sort of 6DJ8/Tesla E83CC-looking. Filament current is a bit lower (6.3V/224mA = more efficient cathode??).
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Re: new English made ECC81/82/83 types!?

Postby Brian Wallace » Mon Sep 08, 2008 8:35 pm

The structure does look odd and it's got me wondering what they would sound like.
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Re: new English made ECC81/82/83 types!?

Postby Jeff West » Mon Sep 08, 2008 8:49 pm

Hi guys, I just got through watching the film after seeing the link Tubemonger posted on asylum, fantastic!

Yes indeed, a tube that's not afraid to forge it's own path, visually. Do we call those dual "inkwell plate" triodes?
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Re: new English made ECC81/82/83 types!?

Postby Brian Wallace » Mon Sep 08, 2008 9:25 pm

The picture in the PDF file looks like an old oil can. :D
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Re: new English made ECC81/82/83 types!?

Postby Jeff West » Wed Sep 10, 2008 10:26 pm

I really like the look of that tube in the photo, with the flying wire and everything. Logo might not be gellin with it though. Should we expect extended high end with these?
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Re: new English made ECC81/82/83 types!?

Postby dai h. » Thu Sep 11, 2008 5:28 am

seems like the high frequency response would be more extended with less cap.(so less feedback). The grid connection appears to be that outside wire coming in from the top. Also wonder what the top part connected to the getter is? (Acts as a shield?) See no mica (which is an insulator) and that middle piece looks like it's metal. It's a planar tube (planar = on a plane with PGK side by side as opposed to the usual concentric) so am interested in the specific construction.

Also, good news for anyone wanting to download the film. It is download-able (size: 72.3MB) :

http://www.techtubevalves.com/about_us/ ... 50kbps.flv

saw that here:

http://groups.google.com/group/alt.guit ... a2fe03eabd?
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Re: new English made ECC81/82/83 types!?

Postby BryanL » Thu Jun 11, 2009 8:17 pm

They appear to be having production problems with these. The spread in anode current between the 2 halves is wide, and there is a microphony problem, too. I see the parent company supplies CRT cathodes to many CRT makers; I reckon these are used in these tubes. Hence the planar construction. It is very similar to that used at MOV for disc sealed triodes for UHF up to 3Ghz. I guess they are having problems making a grid rigid enough. The wire must be very fine, and closely wound, as these cathodes are relatively small in area. We had to polish the DET29 cathode surface after hydraulically compressing it at 2500lbs/sq. inch to get a really flat surface! A 12AX7's mu of 100 with such a small cathode magnifies any flapping about of wire in an accoustical breeze.

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Re: new English made ECC81/82/83 types!?

Postby neikeel » Sat Jun 13, 2009 11:11 am

I read through all the bumph and they seem to admit that microphony is a problem at certain frequencies.

I imagine the only way to find out if they are any good is to order one (£26.00 + vat + p&p) and abuse it in one of my amps :D

My Mullard EF86s usually sound really good before they become microphonic and die :(
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Re: new English made ECC81/82/83 types!?

Postby Jeff West » Sun Jun 14, 2009 1:18 am

Yeah. The late Bernie Majors, of WE and Sylvania before that, wrote of planar tubes in general six years ago: "Planar construction puts active elements in parallel planes perpendicular to the axis of the tube, which minimizes lead inductance and interelectrode capacitance. Tubes with this construction had disc seals, with round electrode connectors sealed to the glass bulb. Disc-seal construction gave low end inductance and facilitated RF connections, advantages that became increasingly important at frequencies above 1000MHz."

There's an interesting article in Tube Collector (12/05) by Lane Upton, who starting in early '66 was charged with enlarging and trouble shooting the planar-triode product line for Eitel-McCollough (EIMAC) as it was expanded and production and engineering was moved from California to Utah during that heady time. Unlike the Techtube 12AX7s, these were mostly high voltage planar tubes for RF and voltage regulator applications. But in common, a persistent problem was mechanical movement of the grid. At high power dissipation, the grid (which can be characterized as a fine, ideally flat screen in these planar jobs) would tend to "pop" over center abruptly, I guess like one of the old fashioned "clickers" made of spring steel. Also, at pulsed repetition rates as voltage regulators or in other applications inviting oscillation the grid would begin to resonate. Various mechanical fixes were employed, including stronger brazing of the grid mesh onto its mounting washer to raise resonance freq, and ultimately the employment of a tungsten support structure brazed onto the grid, fashioned like a wagon wheel with five spokes, which added rigidity and also enhanced heat dissipation. Apparently these were highly successful. Perhaps there's a lot that's not so new under the sun, thermionically speaking.

Agree with neikeel that we'll have to get 2 or 3 and try 'em.

Might want to try a cool Philips 6084 as a quiet sub for EF86, too. Bryan- do you have any comments on those tall super valves (or sister 6085s, which are nice in VOX AC50 instead of 12AU7)???

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Re: new English made ECC81/82/83 types!?

Postby neikeel » Sun Jun 14, 2009 8:33 am

Thanks for the heads up on the 6084, Jeff 8)
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Re: new English made ECC81/82/83 types!?

Postby BryanL » Sun Jun 14, 2009 7:48 pm

Jeff, you are a wonder! the font of knowledge and all that b-----ks. (Wima said this word in the Flintstones on British ITV in 1967 at 6pm, and no-one complained. { yep I transmitted the video tape!} Nowadays one needs approval from the "authorities" to use "foul language" on TV before 9pm)

The DET22/3/4/ 7/9 were all made as you say. For the DET29 the girls in the "clean room" (less than 1 micron!) used capacitance-bridges to get the cathode in the right position relative to the grid. But a disc-seal triode is a much easier job to do than line up stuff in micas. I will email these guys (to tell them how to suck eggs, no doubt!) about how we got the grids rigid enough in these little effers. Also had a nostalgia relapse--I am 70!-- and remembered a high gain triode tube numbered R5559 used in the 1957 EMI CPS Emitron TV cameras, at the front end, just after the photo-sensitive stage. Later cameras used RCA nuvistors and then Motorola FETs. Any microphony induced by camera vibration or from the PA on the floor was a no-no. (Bars across the picture in tune with movement/audio). Two different problems, with the same solution.

I wish these guys luck with their tubes. It is possible they could be better than a 12AX7 type with triple micas and clamped grids as in the CV4--- series.

Not sure about the "using the ex Blackburn Mullard factory" bit. Guess these guys are on a redeveloped area originally used by Philips/Mullard Blackburn. Good PR. Quite happy to be corrected on this.

Just a throw away--, after WWll, Mullard expanded its Mitcham factory. The plans came from Philips Eindhoven. Yes, you've got it already! Mars, and NASA, were beaten by 50 years! The builder used the wrong conversion, and the floors between the 2 buildings went from a 0.3 inch gentle ramp to several steps at the top storey over the junction between the two buildings.

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Re: new English made ECC81/82/83 types!?

Postby Jeff West » Wed Jun 17, 2009 10:05 am

Bryan- I usually find your first-hand info of greater interest than my vicarious!

If you end up getting any input to share from former colleagues concerning construction/production that would be great.

I think the Techtube operation is on a part of the old Blackburn site, although not with any old equipment. Don Butler was writing in another forum about having visited Blackburn in early '90s (?) and buildlings were there but all emptied out.

JW
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Re: new English made ECC81/82/83 types!?

Postby David B » Sat Jul 04, 2009 12:48 pm

Now available.
https://shop.blackburnmicrotech.com/sto ... stockid=17
anyone try them ? field reports
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