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What is this 6386 tube limiter that I have?
Old 1 week ago
  #1
Gear Nut
 

What is this 6386 tube limiter that I have?

Hello there.

Years ago I acquired this old tube limiter for not too much cash.
I always assumed it was a "custom" Gates Sta Level - possibly one that was built into a broadcast rack at a radio station or something..

I have thought about selling it a few times, but plugged it up recently and loved what I got out of it.

I wondered if anyone could shed anymore light on what I have here.
I feel like the "Sta Level" meter is slightly misleading, although the tubes seem to match those of a Sta Level:

2x 6v6, 1x 12AT7, 1x 5Y3, 1x OB2, 1x 6386

The input and output transformers are throwing me a bit, as the input is a UTC HA100X (as in the original LA2) and the output is a Triad S-32A (500ohm)

Anyone offer any info on this Frankenstein limiter I have? Was it common for things to built from kits for broadcast facilities?

Cheers

[IMG][/IMG][IMG][/IMG][IMG][/IMG][IMG][/IMG][IMG][/IMG]
Old 1 week ago
  #2

With a pair of 6v6 and a 15w output tranny, It's more than line-level... The fact that it's a 500ohm tap is interesting. I'd say it's probably a distribution amp or a driver for an RF box. Still, 2x6v6 seems like overkill.



-tINY

Old 1 week ago
  #3
Lives for gear
 
bgood's Avatar
I bet it’s some Frankenstein gizmo an engineer at a radio station made outta parts... they did that all the time back in the olden times
Old 1 week ago
  #4
Gear Nut
 

Cheers for the input guys.
Yeah I'm starting to think it's a bit of a Frankenstein. It would probably work as a guitar amp, thinking about it now!
Old 6 days ago
  #5
Lives for gear
The Sta-Level came from the factory with push-pull 6V6s. It was designed to drive long, low impedance telco lines to the transmitter.

Factory version also used a 6386, which is a dual triode with a special transfer curve that's helpful in dynamics control.
Attached Thumbnails
What is this 6386 tube limiter that I have?-stalevel.jpg  
Old 6 days ago
  #6
Quote:
Originally Posted by Jay Rose View Post
The Sta-Level came from the factory with push-pull 6V6s. It was designed to drive long, low impedance telco lines to the transmitter.

Factory version also used a 6386, which is a dual triode with a special transfer curve that's helpful in dynamics control.


Still seems like overkill - but the 6AQ5 was not a high-run tube (nor was the 6k6)....



-tINY

Old 6 days ago
  #7
Lives for gear
Quote:
Originally Posted by tINY View Post


Still seems like overkill - but the 6AQ5 was not a high-run tube (nor was the 6k6)....


There’s no 6K6 in the box.

If you mean 6V6, it was one of the most popular tubes in mid-power amps, radios, etc. Pin compatible with 6L6, but lower power. Some folks prefer V in their guitar amps designed for L, because they feel it adds warmth.
Old 5 days ago
  #8
Quote:
Originally Posted by Jay Rose View Post
There’s no 6K6 in the box.

If you mean 6V6, it was one of the most popular tubes in mid-power amps, radios, etc. Pin compatible with 6L6, but lower power. Some folks prefer V in their guitar amps designed for L, because they feel it adds warmth.

If you want the characteristics of a 6v6 but only need to run a few watts, you can design an amp that will run a 6v6 on lower voltage and produce less than about 10w per tube. Both the 6k6 and the 6aq5 can be substituted in a 6v6 circuit running on lower voltage an producing less than about 6w per tube.

TDSL Tube data [6AQ5]

TDSL Tube data [6K6]

TDSL Tube data [6V6]




-tINY

Old 5 days ago
  #9
Lives for gear
Indeed yes. But the OP was asking about what looked like a DIY compressor, both it and the original StaLevel used push-pull 6V6, and someone brought up that the 6K6 wasn't high-run.

My answer was that the originally queried 6V6 was indeed high run. As was its high-run higher power brother, 6L6 (or 807 or 5881).

Now... could Gates have designed it differently? Of course. I'd say it's possible that StaLevel used 6V6 at a lower voltage than normal because they didn't need the power... can't tell without an original schematic.

Further, I'd guess they used 6V6 because it was such a common, any-drugstore tube. Transmitter compressors are mission-critical for radio stations -- and these were the days when AM airtime was Big Money. They need to be fixed quickly.

Ditto the push-pull... they could have done a single-ended output, but a push-pull will still generate an output even if one tube fails.
Old 5 days ago
  #10
Lives for gear
 
emrr's Avatar
Looks like a station built DIY Stalevel to me, certainly looks like an original meter which could have been purchased as a spare part. Many aspects are old tech, not stuff someone would have on hand to use today. Interesting that R36 looks like a Gates bracket and part number stamp, but not the one form a Stalevel, which is also R38. It looks like the bracket from an SA-39, but that's R3.

Last edited by emrr; 3 days ago at 06:07 PM..
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