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Question: Amphenol 7 pin connectors on old mic pre. Pls Help
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wolffproaudio
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Joined: 19 May 2016
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PostPosted: Thu May 19, 2016 5:07 pm    Post subject: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Hi all! I have come across a lunchbox rack of 6 interesting old mic pre's with no markings or brand other than "SQ-305-1 Microphone Amplifier" on each module, and "B&K Instruments, Inc, Cleveland Ohio" on the power supply. There are also a few metal inventory tags from Pratt & Whitney (airspace company?). I can find no record or mention of these preamps anywhere in my internet searches.

The unit powers up! Smile It is extremely clean.

The big question: It's input connectors are Amphenol 7-pin barrel type
Sad I assume they may have been for tube mics or something like that? Outputs are BNC unbalanced.

I'm wondering if it could be possible to adapt these 7 pin inputs to accept conventional microphone signal. I'd love hear if these pre's are anything useable.

Does anyone here have experience with this type of connection, or know if there is a standard pinout diagram I can find anywhere? I've been scouring the net for 3 days straight and need some pointers.

Thanks so much!
~Dorian


Last edited by wolffproaudio on Thu May 19, 2016 6:07 pm; edited 1 time in total
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Nick Sevilla
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PostPosted: Thu May 19, 2016 5:28 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Hi Dorian,

AS all things internet:

"Pictures or it didn't happen"

Cheers
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wolffproaudio
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PostPosted: Thu May 19, 2016 5:55 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote


one of the pre's


Pratt & Whitney inventory tag


power supply on lunchbox


more pre's


another tag


Mains in (wurlitzer type oval)


7 pin inputs, BNC outputs


Inside view of 7 pin connectors. Black lines all appear go to chassis/ground, leaving Blue, Purple, Yellow, and Yellow/White to be investigated.


the unit powered up
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wolffproaudio
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PostPosted: Thu May 19, 2016 6:00 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

It might even just be some weird old piece of test equipment, but I'll be darned if it doesn't seem like a set of preamps.
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Drone
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PostPosted: Thu May 19, 2016 7:28 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

B&K Instruments, I think are BK Precision, makers of DMM's Capacitance Meters etc.

They can probably give you all the info you need.

http://www.bkprecision.com

I'm betting it's something semi-custom made for Pratt Whitney, though why an engine manufacturer requires mic preamps? For noise level testing maybe?
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dfuruta
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PostPosted: Thu May 19, 2016 9:56 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

i would guess this is bruel & kjaer, not bk precision, from the color & style of the faceplate. most likely this would have been intended for vibration or acoustic analysis.

edit: and the logo is pretty close to their current one...i've had some b&k test gear of that vintage, which looked quite similar, but i've sold it and am thus unable to take a look at the logo. they're likely quite nicely made preamps but might have been designed for specific frequency response, input level, or other things that'll render them unusable in a musical context.
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Drone
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PostPosted: Thu May 19, 2016 10:23 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

I have one of their filters, it's an old tubey beast in Gray Hammerite, I can find a pic tomorrow.

You do get hits on their website searching for sq stands for sound quality, nothing on the model number tho.
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PostPosted: Fri May 20, 2016 9:21 am    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Take a look around page 208 of this, there's your 7 pin Amphenol connector in use.

http://www.bksv.com/doc/ba5105.pdf

I imagine they use the same pinout thru-out the ages (click below).

http://www.bksv.com/~/media/New_Products/LAN%20XI/Frontpanels/ua2102/LAN%20XI%20Lemo%20Pin%20out.ashx?mh=600&mw=600&bc=white

Be super careful, they talk about using a 200V polarization voltage, if your modules are delivering that it could knock you on your ass.
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Nick Sevilla
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PostPosted: Fri May 20, 2016 9:50 am    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Hi,

This is a 6 AIRCRAFT headset microphone amplifier system made for an aircraft. The "no heat" label at the top of the mic amplifier means that this unit can be used in any weather, and at almost any altitude, without requiring a heater unit in the aircraft to function properly. That is what gives this away as an aircraft comms system.

It is a B&K Precision instruments model SQ-305-1, serial number 102. NOT Bruel & Kjaer, LOL.

The microphone connectors are for TWO WAY headsets, common in military and older
civilian aircaft. These have fallen out of use in civilian aircraft, but not in military ones.

The plaque of Pratt & Whitney is probably NOT originally a part of this unit, however, it may have been used as part of an overall Pratt & Whitney retrofit of a large aircraft. Although Pratt & Whitney is known for of all things rocket engines and WWII propeller engines for our famed Mustang P51 fighter aircraft, they also almost always do custom stuff, mostly for military and large civilian air contracts. If they get a contract to service a fleet, they do all the maintenance, retrofits, etc. Gotta stay competitive.

The stickers "29" and "30" above the microphone connectors are meaningless, and on the front panels of each amplifier unit, ignore them. Someone put them on there long after this unit left the aircraft or even the control tower it came from. Being as it is a multi channel unit, that is also a possibility.

The AC three prong center offset connector looks like it is from the 1950s or 1960s, so this unit is definitely old.

I would start by emailing these kinds of places for some understanding as to the wiring of the mic connectors, as they are pretty standard:

http://aircraftprecisioninstruments.com/

And other places like aircraft restoration forums and old aircraft fan sites, even maybe some HAM radio forums, they should have more details on this model.

Lastly, the company might still exist, although I seriously doubt they have the schematics, but you are welcome to try them out:

http://www.bkprecision.com/about-us.html

Here are a few links to aircraft stuff to get you going:

http://aircraftproducts.wicksaircraft.com/category/avionics-intercoms

http://www.skygeek.com/aviation-communications.html

And what a new plug looks like, not a bad price either:

http://www.ebay.com/itm/Metal-Flange-25mm-Head-GX25-7-7Pin-Male-Aviation-Plug-Connector-/231132303758

A possible pin out (TELEX standard mic with two earpiece):

http://www.watamix.com/rtspinouts/#US14

Another possible pinout, Sennheiser (based on the standard type):

http://plsystem.com/pinout3.htm

Look for model HMD-26-X

CHEERS.
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wolffproaudio
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PostPosted: Fri May 20, 2016 2:12 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Thanks Nick! I had suspected aeronautical use when I saw the Pratt & Whitney tag but didn't know enough to be certain.

I'll post results here, if I get any.

~Dorian
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Drone
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PostPosted: Fri May 20, 2016 4:58 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

No, I think dfuruta was correct, when he corrected me from B&K Precision to Bruel and Kjaer, I looked for B&K Instruments in Cleveland OH, and got Brujel and Kjaer NOT B&K Precision (bloody confusing innit) Shocked

http://lcweb2.loc.gov/master/mbrs/recording_preservation/manuals/B&K%20Short%20Form%20Catalog%20%281973%29.pdf

Is a copy of one of their old catalogs.

B&K Precision was named for Philip Ban and Carl Korn in case you care. They started in Illinois, not Ohio.

But yeah, contact Bruel and Kjaer not B&K precision Rolling Eyes
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wolffproaudio
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PostPosted: Sat May 21, 2016 2:09 am    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Thanks Drone, I just looked at that catalog PDF and the first thing that caught me was the logo. The B&K badge on the back of the unit I have is identical.





Last edited by wolffproaudio on Sat May 21, 2016 3:02 am; edited 2 times in total
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Drone
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PostPosted: Sat May 21, 2016 8:31 am    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Did you see this pinout?

http://www.bksv.com/~/media/New_Products/LAN%20XI/Frontpanels/ua2102/LAN%20XI%20Lemo%20Pin%20out.ashx?mh=600&mw=600&bc=white

Does it match?

Like I said earlier, watch for voltages, some of the more recent Bruel and Kjaer units have a switchable 200/28/0V polarization voltage, plus the power supply may also be on that connector.
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dfuruta
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PostPosted: Sat May 21, 2016 12:00 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

Nick: I don't think you know what you're talking about. I've never seen aircraft equipment of that vintage on 115VAC with that sort of plug (28VDC is much more common, and AC power is generally marked 400Hz); I also don't believe that BK Precision has ever built aeronautical equipment (although I may be wrong on this). The Pratt & Whitney badge most likely indicates that they owned this unit in their R&D lab, or just that someone put it on later to look cool...

Those AC connectors were common on test gear from HP, Fluke, and similar from the 60s (as well as radios, calculators, etc). Belden still makes them with part #LL14847. I unfortunately don't know the proper name for this jack.

You may not know that Bruel & Kjaer's main business is testing equipment for vibration & acoustic analysis, not audio recording microphones (spun off into DPA). Locking connectors make sense in this context.

Every aircraft radio unit from this era that I've encountered takes up far less panel space than this - it's hardly space efficient to have this sort of layout.

EDIT: the "29", "30" stickers suggest that this was originally one of several units being used in conjunction to test something...
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PostPosted: Sat May 21, 2016 4:26 pm    Post subject: Re: Question: Amphenol 7 pin connectors on old mic pre. Pls Help Reply with quote

dfuruta wrote:

Those AC connectors were common on test gear from HP, Fluke, and similar from the 60s (as well as radios, calculators, etc). Belden still makes them with part #LL14847. I unfortunately don't know the proper name for this jack.

I've actually heard them call Belden cables. They were superseded by the ubiquitous Euro connector, or kettle lead (it's a UK thing) because the contacts on the belden cable were too close to the end of the connector making it a shock hazard.

Not that that's important. If those 7 pin Amphenols are the same as the LEMO's then you might have your pinout, there's a signal in and a signal ground, as well as power ground / chassis, so that would be where I'd start, but first check there's no shock hazards with a voltmeter Crying or Very sad

If they are different from the LEMO, that other PDF I pasted, right at the back of the manual is a conversion pin out for another 7 pin cable to the LEMO type.
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