Lomo 19A9 tube shootout?

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B-A-R

Active member
Joined
Jan 19, 2005
Messages
42
Location
Cali
Hey folks, wondering if anyones played with diff mauf. of the 6AK5 (EF95) for use in the Lomo 19A9's??

Ive seen G.E., Valvo, Western Electric, etc... Just curious if anyone had a favorite...

What an amazing Vocal mic!!

B
 
Darn! I just threw out about ten of those things to make room in the tube caddy.
You have a schematic?

$3.60 NOS at tubesandmore.com

Looks like an old TV tuner tube, miniature VHF.

You can call them and ask what brands they have. Usually they have a selection.
 
hey thanks for the info....yea, they seem to be plentiful, but i was just wondering of someone noticed any sonic or performance differences between the different manf.

b
 
The 5840 tube used in the Royer mic is supposed to be similar electronically to the 6AK5:

http://frank.pocnet.net/sheets/137/5/5840.pdf

I had thought about trying a DIY mic with a 6AK5, because they are CHEAP, and it appears that a lot of good brands are available.
 
I have a bunch of Vacuum Tube Valley magizines that have tube shootouts, but unfortunately they are for common types like 12AX,6V6, 6L6, 6DJ8, etc.

That tube crosses to an EF95. If you can find an Telefunken or Phillips EF95, you might find the holy grail for the AK.

cj
 
I tried a handful of western 6AK5 tubes in this mic (GEC, Raytheon, and another IIRC - I'll check), but found that the soviet 6X1Pi tubes were audibly better in terms of noise.

Stewart
 
I have half a schematic - I got the mic but NOT the original PSU. We can guess the rest, but it would be nice to have this confirmed by someone.

Lomo19A9schem.gif


So it looks like the plate resistor, cap and trafo are in the PSU. The connector has just 4 pins. So what I marked as "B+" is really the voltage after the plate. 50-60V was a guess based on the info at Michael Vladimirsky's site (microphones.ru). The circuit works fine at this voltage.

And yes, before you ask, - I am pretty sure about the capsule being wired directly to "B+".

[BTW, apologies for diappearing for a few months - life has just been overwhelming and something had to give!]

Stewart
 
ooops!! sorry, i have no schematic info at all on this mic or PSU, i guess i was just after opinions on the sonic charachteristics of different tube manf in this specific app. i could shoot some pix of the PSU innards, if thats a help to anyone??

I prolly shoulda posted this in the brewery, but im green, and just gave it a shot!
:grin:

Thanks for the help, i got my eye on a few tubes on evilbay, they are cheap, might post listening results in the appropriate forum if all goes well....

b
 
Let you ears be the judge!

Pix of the PSU would be nice - try to read any values on parts too if you can.
 
Cool, i got some GE and some Valvo's on the way....will check em out.

I will try to get some pix of the inside of the PSU this week. Also, a friend with this mic spoke of a mod wherein changing the value of the electrolytic in the mic can give it more bottom...i will hunt down the details.....

b
 
hey there.....changed the tube, used an NOS Mullard. Sounds great. Not as fat as my 19A19, but nice upper-mids, and big bottom.

What email addy should i send a pic of the PSU to??

b
 

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