Pen-toad Question

wrenchone · 25th February 2010, 08:16 AM

I'm thinking of using a triode-connected 6EJ7/EF184 pentode with current source loading as input/driver tube for an upcoming project. I have the choice of some Euro-made tubes that have an extremely sexy-looking mesh plate (I know it sounds perverse, but I'm an engineer, so WTF) and some domestic brands that have blackened envelopes that may visually veil the inner goodies but may also have lower distortion. Comments?

planet10 · 25th February 2010, 08:24 AM

I have some EF89 (IIRC) that have that lovely mesh plate... know what you mean.

dave

Bandersnatch · 25th February 2010, 10:32 AM

hey-Hey!!!,
I think the mesh is just a screen. The anode should be a small solid plate on both sides of the cathode. That said, the open structure of those tubes is decidedly nice looking, and who am I to suggest a plain looking tube...heh-heh-heh.
cheers,
Douglas

DF96 · 25th February 2010, 02:36 PM

Yes, the mesh is a screen. You will find this design in many Philips group pentodes and, with a different appearance, some Russian ones. They prefer anode cooling via holes in the screen, while other makers (German and US) prefer a grey solid screen which absorbs and then re-radiates the infra-red from the anode. I don't know any valves which have a mesh plate, but it is a phrase which people outside Europe often use when describing the screen.

Captain archer · 25th February 2010, 04:34 PM

I think it is a good choice to use these EF184 tubes in audio.
I used it in a microphone amp ones and the shield comes in very handy at low level signal aplification.

wrenchone · 05:55 PM

Yes, we all agree that the screen is very pretty. This is also a question of aesthetics vs. function. I suspect that the 6EJ7s with the blackened envelopes may be better performers based on some comments by Morgon Jones regarding 6SN7 variants with blackened vs. clear envelopes. That is, unless the screen serves a similar purpose.

25th February 2010, 08:16 AM	#1
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	Pen-toad Question I'm thinking of using a triode-connected 6EJ7/EF184 pentode with current source loading as input/driver tube for an upcoming project. I have the choice of some Euro-made tubes that have an extremely sexy-looking mesh plate (I know it sounds perverse, but I'm an engineer, so WTF) and some domestic brands that have blackened envelopes that may visually veil the inner goodies but may also have lower distortion. Comments?

25th February 2010, 08:24 AM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	I have some EF89 (IIRC) that have that lovely mesh plate... know what you mean. dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

25th February 2010, 10:32 AM	#3
Bandersnatch diyAudio Member Join Date: Jul 2003 Location: Ann Arbor, MI	hey-Hey!!!, I think the mesh is just a screen. The anode should be a small solid plate on both sides of the cathode. That said, the open structure of those tubes is decidedly nice looking, and who am I to suggest a plain looking tube...heh-heh-heh. cheers, Douglas __________________ the Tnuctipun will return

25th February 2010, 04:34 PM	#5
Captain archer diyAudio Member Join Date: Apr 2004 Location: Weert	Good choice I think it is a good choice to use these EF184 tubes in audio. I used it in a microphone amp ones and the shield comes in very handy at low level signal aplification.

25th February 2010, 05:27 PM	#6
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	Yes, we all agree that the screen is very pretty. This is also a question of aesthetics vs. function. I suspect that the 6EJ7s with the blackened envelopes may be better performers based on some comments by Morgon Jones regarding 6SN7 variants with blackened vs. clear envelopes. That is, unless the screen serves a similar purpose. Last edited by wrenchone; 25th February 2010 at 05:55 PM. Reason: sp

25th February 2010, 02:36 PM	#4
DF96 diyAudio Member Join Date: May 2007	Yes, the mesh is a screen. You will find this design in many Philips group pentodes and, with a different appearance, some Russian ones. They prefer anode cooling via holes in the screen, while other makers (German and US) prefer a grey solid screen which absorbs and then re-radiates the infra-red from the anode. I don't know any valves which have a mesh plate, but it is a phrase which people outside Europe often use when describing the screen.

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