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View Full Version : [Help Needed] Tube question EM87


heiney9
04-23-2009, 11:34 AM
I've got this nifty little tube hybrid integrated amp (Dared MP5, Fatman, etc) and it uses a 3rd tube EM87 as pictured. I have tried in vain to try and find out if this tube is just for show or if it is actually in the input circuit.

The reason I ask is because the one that comes with the unit is a cheapie Chinese brand and I have found some 1960's NOS EM87 tubes. If it has no effect on the sound I'm not shelling out the extra dough for Siemens or Amprex Orange Globe, etc.

Is this particular tube as it was used in the 50's and 60's as a tuning indicator typically in the signal path?

TIA for all the input.
fredv
04-23-2009, 11:46 AM
It is just for show, kind of like the old volume meter, no impact to the sound.
reeltrouble1
04-23-2009, 11:52 AM
A show tube?? Well I suppose anything is possible but unless its on a totally seperate line it would be in the path. Any reason then you cannot remove it and see what happens?

RT1
187CAM
04-23-2009, 12:49 PM
http://www.vacuumtube.com/eyetubes.htm
ND13
04-23-2009, 12:53 PM
Cat's Eye. Rich had one in each of his TADS iirc.
heiney9
04-23-2009, 12:54 PM
http://www.vacuumtube.com/eyetubes.htm


Thanks, I did come across that info while searching. Great explanation and history of the "cat's eye" tube. It really doesn't say if it's part of the signal path or not. Unless I missed it.

I suppose I could infer based on the info in that thread that's it's not in the signal path.......but I'd like to know for sure.

Thanks Ted, great suggestion I had been thinking about too. I'll pull it out tonight and see what happens.

H9
187CAM
04-23-2009, 01:58 PM
I tried to do a comparison on my HTC iPod amp by letting it warm up good then removing the tube and turning the unit back on as quickly as possible. (gloves on ofcourse in case of heat) I didn't notice any difference in sound quality. I'm contacting Dared to see if anyone there can answer the question since I don't have the schematic for this amp.
heiney9
04-23-2009, 02:10 PM
I tried to do a comparison on my HTC iPod amp by letting it warm up good then removing the tube and turning the unit back on as quickly as possible. (gloves on ofcourse in case of heat) I didn't notice any difference in sound quality. I'm contacting Dared to see if anyone there can answer the question since I don't have the schematic for this amp.

Mine is an HTC as well. I couldn't find a schematic either and while I haven't tried to contact Dared those that have read about didn't really get a good response. But, keep me posted if you find anything out.
SCompRacer
04-23-2009, 03:46 PM
Cat's Eye. Rich had one in each of his TADS iirc.

Wow, good memory! The TAD-60's and TAD-1000's had the 6E2 VU meter tubes in them. Paul said they could be removed from his amps without harming the circuit. They were hi-beams-on distracting in a dark room.

http://www.polkaudio.com/forums/attachment.php?attachmentid=17427&d=1151199971

http://www.polkaudio.com/forums/attachment.php?attachmentid=17429&d=1151199999