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Anyone know a lot about vintage Shure's? (and a Multivox unit?) Nice score from grandma's attic

#1 User is offline   hellion102792 

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Posted 10 January 2012 - 01:04 AM

Anyone familiar with vintage Shure mics? I can't find much on google about this one, it's a Shure A88A that dates back to at least the later 50's/early 60's (judging by it being mentioned in comparison to another mic in Shure's 1959 catalog). Apparently my dad's uncle gave it to him when he was a kid and I found it in my grandma's attic/his old studio location yesterday. It's got this weird female input that I've never seen on any kind of mic, it's like 3 slots arranged in a triangle. I'm guessing I have to special order this type of cable or find an NOS one on eBay? It also features a grip-to-talk switch that locks into place, so I'm assuming its uses would include CB radio and that sort. I'd love to try laying down some vocals with it once I find a cable to see how it sounds.

Now for the obligatory pics:

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Odd input:
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Seen in the back of the mic is one of my dad's old rackmounts from the 70s, a Multivox Analog Echo MXD-5, which I am having a lot of fun playing with. It was up in the attic hidden behind some stuff on a shelf. Again I can't find much info on google about it, it's an awesome little unit with spring reverb and what sounds like a tape delay. For all I know it could be a bucket brigade circuit, but it sure sounds and acts/reacts like any real tape delay I've ever tried. Awesome unit nonetheless, when I hook that sine generator from the attic in it can make some awesome sounding Twilight-Zone-flying-saucer-type sounds. Anyone familiar with this unit?

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Thanks!
___________________________________________________________
Live your life, do it your way.
Guitars:
192? Unidentified Pre-Great Depression acoustic Archtop, on the hunt for info
197? Un-named (Cortez?) Les Paul Custom copy
197? Yamaha FG-200 Acoustic
1969 Harmony Sovereign H1270 12-string- Dead and gone, RIP
1985 Guild D-17m Acoustic w/pickup
2004 Squier Affinity Stratocaster
2007 Martin D12X1 12 string Acoustic
2007 Lucero L100 Classical-Sold to a loving home
2008 Gibson SG Special in Worn Cherry, w/Mean 90 P-90 in Bridge position

#2 User is offline   L5Larry 

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Posted 10 January 2012 - 09:35 AM

That's some really neat old gear. I always wanted an AF Generator on my workbench to play with.

As for the microphone, the connector is what we used to call an "Amphenol" connector, and was used by Shure at least through the late 60's (on certain models) before the XLR connector became the "industry standard". "Amphenol" was the manufacturer, and the specific connector you need will have some number/letter code designation, for which I can not determine at the moment (I will look further). I have seen microphones with this connector on e-bay (Shure PE-54 is one), so a cable or connector is out there somewhere.

The mic as pictured and configured was most likely a high-impedance communications type microphone (2-way radio, intercom/paging, etc), and are not really known for their audio quality (but they sure do look cool).

#3 User is offline   L5Larry 

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Posted 10 January 2012 - 12:24 PM

I have not yet found the model number of the Amphenol connector you need, but.... looking through my old catalogs:

As late as May of 1974 Shure still offered the C5-3 cable that had the Amphenol on one end and a 1/4" jack on the other (at the time being used on the PE-54 and PE-55 mics). The connector required will have three round pins, not flat blades (the slots are needed for the manufacturing process of the connector itself), in an almost equilateral configuration, with a "keyway" on the barrel (to fit in the slot on the mic).

I also see from your photos that it has the variable impedance switch (L,M,H). This will allow you to use this mic with a high-impedance input (1/4"), or low impedance input (XLR). I have a REALLY old "55" with this switching capability, and have found the "M" setting to work best with todays XLR low impedance inputs. On my 55 I also removed the old Amphenol connector and wired in an XLR pigtail for use with any standard XLR mic cable.

Important Tech Note: Due to the age of this mic, and the fact it has been sitting unused for a long period of time, the diaphragm may be seized up. If this is the case (and most likely will be), this DOES NOT mean the mic is dead (it's just sleeping). If the diaphragm coil shows resistance on an Ohm meter (not "infinite" [open/broken coil], or "0" [shorted coil]), this mic can be resurrected with a jumpstart from a 9v battery. If you get this far in the project, PM me for jumpstart details.

That's all I got. Good luck and keep us posted on your progress.

#4 User is offline   L5Larry 

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Posted 10 January 2012 - 12:35 PM

One more thing to add:

Looking at your photos again.....

The "A88A" is model number for the added switch, not the microphone. The blue metal tag on the mic itself will give you the microphone number, and hopefully assist in your research.

The A88A seems to be an add-on switch component, and should be removable from the mic proper. Then you can see what type of connector is between those two components, and that would be the connector type you would need on your cable if using without the add-on switch.

#5 User is offline   L5Larry 

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Posted 10 January 2012 - 12:43 PM

OK, last add....REALLY

A quick Google identifies the microphone as a Shure model "51".

#6 User is offline   hellion102792 

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Posted 10 January 2012 - 02:13 PM

Wow...this is extremely helpful! I was so excited when I found it that I failed to notice the blue tag, and yes that states it to be a model 51.

I just took it apart from the switch adapter, found that there's the A88A adapter as well as an on/off dial adapter made for this mic.
Still an Amphenol inside the mic itself, here's the current pics.

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And I'd be looking for a cable like this, correct? This is the connecter inside the A88A. I have some soldering skills, maybe I could possibly graft this onto an XLR or 1/4" cable?
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Very helpful Larry, thanks a lot. Once I get a cable I can see if the diaphragm is seized, if that's the case I would love the 9v procedure. I know when I found my Shure Unidyne III at school it didn't work until I hooked it up to a preamp without realizing the 48v phantom power switch was on, I wonder if that resuscitated it.
___________________________________________________________
Live your life, do it your way.
Guitars:
192? Unidentified Pre-Great Depression acoustic Archtop, on the hunt for info
197? Un-named (Cortez?) Les Paul Custom copy
197? Yamaha FG-200 Acoustic
1969 Harmony Sovereign H1270 12-string- Dead and gone, RIP
1985 Guild D-17m Acoustic w/pickup
2004 Squier Affinity Stratocaster
2007 Martin D12X1 12 string Acoustic
2007 Lucero L100 Classical-Sold to a loving home
2008 Gibson SG Special in Worn Cherry, w/Mean 90 P-90 in Bridge position

#7 User is offline   hellion102792 

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Posted 10 January 2012 - 02:17 PM

Also just found this link: Wiring of vintage Shure mics: 3 or 4 pin Amphenol to XLR
There's another site that will make one and send it from Europe, translates to around $80. I'm thinking of going the DIY route rather than spending a lot of money without knowing if the mic will even be usable.
___________________________________________________________
Live your life, do it your way.
Guitars:
192? Unidentified Pre-Great Depression acoustic Archtop, on the hunt for info
197? Un-named (Cortez?) Les Paul Custom copy
197? Yamaha FG-200 Acoustic
1969 Harmony Sovereign H1270 12-string- Dead and gone, RIP
1985 Guild D-17m Acoustic w/pickup
2004 Squier Affinity Stratocaster
2007 Martin D12X1 12 string Acoustic
2007 Lucero L100 Classical-Sold to a loving home
2008 Gibson SG Special in Worn Cherry, w/Mean 90 P-90 in Bridge position

#8 User is offline   L5Larry 

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Posted 10 January 2012 - 03:57 PM

From the link you posted I also found this:
http://shure.custhel...816/kw/amphenol

It seems the Amphenol 3-pin connector designation was MC3M. So if you could find an Amphenol MC3M, wire it according to the Amphenol-to-XLR page from the Shure links, you'd be in business. You can and should test the diaphragm coil before proceeding with any expenditures.

There seems to be a lot of very good info on the Shure website. I've also had good luck when contacting Shure by telephone, they have always been very helpful.

#9 User is offline   BentonC 

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Posted 10 January 2012 - 11:42 PM

Very cool gear- I love finding old gems like that. Super cool Multivox too!

Be sure to let us know how the mic ends up sounding.

#10 User is offline   hellion102792 

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Posted 11 January 2012 - 02:31 PM

Thanks for that link Larry, I will check it as soon as I can go grab a multimeter. And thanks Benton, I agree about finding old treasures. So I went ahead and made myself an Amphenol cable today from an old XLR I found lying around:
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And plugged in
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Hooked it up to my Focusrite hoping for the best but expecting the worst, and all is not lost. When turned up all the way a very metallic and soft signal was coming through, recorded it if you want to hear what I mean. Could this be from the diaphragm being seized? I don't have a multimeter on hand at the moment so I can't test the resistance or voltage properly.
___________________________________________________________
Live your life, do it your way.
Guitars:
192? Unidentified Pre-Great Depression acoustic Archtop, on the hunt for info
197? Un-named (Cortez?) Les Paul Custom copy
197? Yamaha FG-200 Acoustic
1969 Harmony Sovereign H1270 12-string- Dead and gone, RIP
1985 Guild D-17m Acoustic w/pickup
2004 Squier Affinity Stratocaster
2007 Martin D12X1 12 string Acoustic
2007 Lucero L100 Classical-Sold to a loving home
2008 Gibson SG Special in Worn Cherry, w/Mean 90 P-90 in Bridge position

#11 User is offline   L5Larry 

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Posted 15 January 2012 - 12:18 PM

I have been asked by PM from the OP to expand upon the microphone part of this discussion.

First, what is on the other end of the XLR cable you dissected? I can tell from the photo that it is some kind of 1/4" plug, but is it TRS or just TS. This mic is most likely designed to operate on a three-wire low impedance input, and may not work with a two-wire 1/4" guitar amp type input, regardless of the selector switch, and even most three-wire 1/4" TRS jacks are for "balanced line-in", not "low impedance mic-level in". Low impedance mic level inputs are generally XLR type, so you would have to solder an XLR cable on to the Amphenol connector, AND have a mixer or preamp with this type of input.

Second, the wire-to-wire connections are very specific. One wire in the wrong place will not perform properly and give a misinterpretation of a bad mic. From my quick scan of the Shure website, I believe the proper pin configuration can be found there, and you must also know the pin configuration of the XLR input in the mixer. Once the connections are made properly, a sweep of the impedance selector switch on the mic will give you sound test (pun intended) of the operation of the mic.

And third, if all above is correct, the course of last resort is to jumpstart the diaphragm with a 9v battery. To do this you will be MOMENTARILY connecting the battery across pins 2 & 3 of the mic. If the pin numbers are not visible on the Amphenol connector as seen on the bottom of the mic, you will have to open the mic up and look for pin numbers on the back of the connector or on the transformer inside the mic. Connect the - of the battery to pin 2, connect a jumper wire to pin 3 of the mic and then "sweep" the other end of that wire across the + of the battery for a quick "momentary" connection. You should hear a click, or thump, meaning that you have forced the diaphragm to move. If the diaphragm has seized, this will free it up. Then retry the selector switch test above to find optimal performance of this mic.

All the above ASSUMES the diaphragm coil and transformer are not "open", or "shorted" (blown), in which case the mic is dead and gone. The kind of small "passive" transformer in this mic rarely go bad, but it IS another link in the chain. And then there is always the "cold solder joint" syndrome to check for.

For any of this kind of work a multimeter is an invaluable diagnostic tool. Anyone who even just "tinkers" with guitars or audio electronics should have one and know how to use it. A cheap big box hardware store "pocket meter" will do the trick in most cases, for your basic checks are for the problems of "zero" resistance, or "infinite" resistance.

That's all I got. The Shure website may also have more (and/or) better information. Good luck, keep us posted.

#12 User is offline   BentonC 

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Posted 15 January 2012 - 11:38 PM

Wow- this is a fantastic thread! Thanks so much for the information L5Larry- very knowledgeable! [thumbup]

#13 User is offline   hellion102792 

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Posted 18 January 2012 - 12:43 AM

As always excellent info Larry.

According to the packaging for the cable this is in fact a TRS 1/4". I kept the original end of the XLR and made notes of which wires go to which pin, so I can reverse the "surgery". My dad has a ton of XLR's lying around at his studio which I can probably grab a connector from.

That sounds like it may be the problem. I also looked on the Shure site for the Amphenol diagram like you said before I soldered the new cable together, and specifically wired each wire to the respective pin.

Unfortunately I am moving back to school tomorrow, so it will be a bit before I get settled and can start tinkering with this mic again. I'll attempt everything you mentioned and try the jump if all else fails. If this mic is in fact dead and gone, then it's not all waste as thanks to you I now know a few things about old mics and getting them to work. Nice decorative piece too I suppose [thumbup]
I'll grab another multimeter as soon as I can, I took a 3 year votech course in Electronics so I know how to use one. Funny story about my last one, it was actually one I built from a kit. One day I left it on and outside on a scorching hot day and a cap exploded, taking a few components with it [scared] Never got around to fixing it.
But again thank you very much, once I'm settled down at school I'll resume working on this.
___________________________________________________________
Live your life, do it your way.
Guitars:
192? Unidentified Pre-Great Depression acoustic Archtop, on the hunt for info
197? Un-named (Cortez?) Les Paul Custom copy
197? Yamaha FG-200 Acoustic
1969 Harmony Sovereign H1270 12-string- Dead and gone, RIP
1985 Guild D-17m Acoustic w/pickup
2004 Squier Affinity Stratocaster
2007 Martin D12X1 12 string Acoustic
2007 Lucero L100 Classical-Sold to a loving home
2008 Gibson SG Special in Worn Cherry, w/Mean 90 P-90 in Bridge position

#14 User is offline   spacealf 

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Posted 19 January 2012 - 08:16 PM

The connector is sort of the same as the modern ones. Just had a ring on it with a beveled edge so the cord did not snap into the mic like modern ones, but the ring turned to screw onto the mic, so the cord whould not fall out of the mic while using it. Looks like the screws are messed up though so if the ring does not turn onto the screw part, well, maybe you could hold it and even use a cord that does not have the ring part on it, but just the 3 connectors like a modern one (except it won't snap in) and if needed, just hold the cord tight unless it fits tight so it won't fall off the mic and make noise ( maybe ) and turning the PA amp down or whatever to plug back in the cord to the mic.
I have an old Electrovoice 664 mic the same way, but that mic has 4 prongs cord on that end, not 3 prongs.

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