ACM 310 mics

[Marik]

Just curious, but has anyone with a 310 looked into getting a "socket" for the subminiture tube?

I don't know any sockets designed specifically fo subminiature (although it very well might be they do exist). For ACM310 to check different subminiatures in a circuit I use a Nuvistor socket, which works fine, but can be pretty tricky to get pinout right. Once the tubes are sorted out I'd solder it, anyway.

 

[Marik]

In the right room with the right piano, I'd tend to think a ribbon would be an excellent choice as well.

I mentioned wanting my ACM-310s as piano mics, but I didn't describe my environment. 99% of my recordings are made in live concert settings - clubs and halls with a wide variety of pianos. I wouldn't choose ribbon mics for most of those settings. The bleed from the back of the figure-8 would be a problem in many cases. And sometimes I would need the crisper high-end of the condenser.

Though I haven't yet tried them on piano, it's the full-bodied midrange of the ACM-310 that makes me think it would be a good choice.

But in a suitable studio, a ribbon mic could definitely be the right choice.

A shy bass of ACM310 could actually work to an advantage in close miking, where proximity takes care of it. Somehow I am always reluctant using tube mics in live setups... just for reliability reasons. When you are in a studio most of the time it is not a problem to stop session to change a mic. If the tube starts acting on you during performance... well, you see my point?

Best, M

 

[pohaku]

Marik,

I seem to recollect that you had investigated the tube used in the 310 (as it was not a commonly used tube) and wondered what you had concluded about the tube, its quality and replaceability?

Thanks!

 

[Marik]

Marik,

I seem to recollect that you had investigated the tube used in the 310 (as it was not a commonly used tube) and wondered what you had concluded about the tube, its quality and replaceability?

Thanks!

The tube 6J1B is a pentode of Russian origin (6Ж1Б) and was used in many Russian mics. I am not sure but 310 might use one Chinese made.
It is triode connected, but what they do in 310 is just cut off a plate, using a screen instead. This kind of connection is very noise succeptible (just get with the mic close to fluorecent light and listen for the hum).

I finally sourced a few (Russian made) those tubes so once I get them will experiment more and can report, if interested.
I also was playing with rather exotic high transconductance/low plate impedance tubes with some excellent results, but it is impossible to find them. The 5840 would be a good substitute, but you will need to get a bunch to sort out for noise. On the other hand something like 6021 or 6111 would be also worth experimenting with.

But if you don't have hum problems, for now I'd leave original tube alone as the main problem in that mic is cheap and crappy transformer.

Best, M

 

[JTC111]

I finally sourced a few (Russian made) those tubes so once I get them will experiment more and can report, if interested.
I also was playing with rather exotic high transconductance/low plate impedance tubes with some excellent results, but it is impossible to find them. The 5840 would be a good substitute, but you will need to get a bunch to sort out for noise. On the other hand something like 6021 or 6111 would be also worth experimenting with.

But if you don't have hum problems, for now I'd leave original tube alone as the main problem in that mic is cheap and crappy transformer.

Best, M

Marik,
Thanks for offering to handle the Group Buy for the 310 tubes and transformers.
Count me in!!!

 

[Marik]

Marik,
Thanks for offering to handle the Group Buy for the 310 tubes and transformers.
Count me in!!!

Cinemag group buy?
Oh wait, shipping charges most likely would absorb the price difference

 

[chance]

The problem with "experimenting" with tubes is the soldering & desoldering until you find the right match.

 

[ittam]

You solder only once: the socket

Cheers

Matti

 

[Marik]

The problem with "experimenting" with tubes is the soldering & desoldering until you find the right match.

... which is only half of the problem as it is so easy to lift those PCB traces, esp. with multiple sold/desold.
If you want to experiment with tubes then indeed, to solder on a socket will be a much better solution.
JUST WATCH THAT PINOUT!!!

Will post a pic later.

Best, M

 

[retro1]

But if you don't have hum problems, for now I'd leave original tube alone as the main problem in that mic is cheap and crappy transformer.

Best, M

Didn't you find the improvements modest, in swapping the transformer out, or was that only in terms of changing what you felt was a lack of bass?