# Microphone



## Paul Running (Apr 12, 2020)

Can anybody identify the model of this Altec mic?


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## spacebard (Aug 1, 2009)

It's a western electric 639 A or 639 B. The A has a 3 position pattern selector switch and the B has 6.

We need to see the back of the mic to confirm.


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## Paul Running (Apr 12, 2020)

I'll try to have the person send me a rear photo. I'm not familiar with mics; I'm interested in purchasing a higher quality, more or less multi-function mic. I would appreciate any tips on this particular series.


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## Granny Gremlin (Jun 3, 2016)

It's aka The Birdcage. Dual elements - dynamic and ribbon the sum/difference combinations of which give you the different polar patterns. It does a thing and you like it or you don't. Versatile-ish. Quality build. Ribbons are easy to repair and at this age you will likely have to replace or at least tension it.

Lot of details here: Altec (Western Electric) 639A, 639B

Make sure it comes with the XLR adapter or it's a PIA, but I suppose you're handy enough to sort that out yourself. They can get pretty damn expensive - I was after one for a bit but couldn't justify it to myself in the end. Currently at least US$1k, sometimes over 2. when I was looking they were barely pushing 1k sometimes; shoulda got one.


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## Paul Running (Apr 12, 2020)

Granny Gremlin said:


> It's aka The Birdcage. Combo dynamic and ribbon the sum/difference combinations of which give you the different polar patterns. It does a thing and you like it or you don't.
> 
> Lot of details here: Altec (Western Electric) 639A, 639B
> 
> Make sure it comes with the XLR adapter or it's PIA, but I suppose you're handy enough to sort that out yourself. They can get pretty damn expensive - I was after one for a bit but couldn't justify it to myself in the end. At least US$1k, sometimes over 2. when I was looking they were barely pushing 1k sometimes; shoulda got one.


Thanks for the link. Yeah, the price is up there...this particular series is well into that bracket however, I've decided to give up on the economy mics...their sensitivity is unpredictable. I am planning to do some recording that requires some descent sensitivity. I'm not too keen on compensating in the preamp stage, I would prefer to have the sensitivity and fidelity starting at the source.


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## Granny Gremlin (Jun 3, 2016)

Paul Running said:


> Thanks for the link. Yeah, the price is up there...this particular series is well into that bracket however, I've decided to give up on the economy mics...their sensitivity is unpredictable. I am planning to do some recording that requires some descent sensitivity. I'm not too keen on compensating in the preamp stage, I would prefer to have the sensitivity and fidelity starting at the source.


I don't think it's the most sensitive mic.

Ribbons have the most dynamic range and bass response (both due to the motor and the fig 8 pattern which has the most proximity effect of all) but also generally require the most gain of any mic type. Dynamics are all over the map (this one would likely be lower a bit to match the ribbon) and condensers are the most sensitive with the most top end (some may think too much) requiring the least preamp gain.

As for fidelity, the birdcage is 40-10k and far from flat (it's a colour mic) which is fine but not up to "modern standards." That may be the ticket, or it may not. There is also the super low Z - 50 Ohms or less, which is typical for the time and mic type but may not be ideal with many modern preamps expecting around 200, so may restrict F response at the extremes even further. Some higher end stuff has input Z selection so that's fine; might be fine anyway, depends on the amp.

For fidelity and sensitivity (and holding it's value) look for a Gefell UM70 (3 pattern) or 71 (card only) LDC. About US1.5k and worth every penny. There's also the UMT models which are the newer transformerless versions - also think the capsule is not interchangable on those; not sure as I have the older UM version where you can swap out the capsules for various SDC ones and even a shotgun. They will also fit in a standard Shure 58 style mic clip if it don't come with a shock mount (the original shock mounts are garbage - a $20 modern Asian made one will be better so don't pay extra for it). Some older UMs are external power supply and not XLR - there are kits (cheap and easy) to convert to phantom+XLR and ones that came stock that way. All the UMTs are phantom and XLR.

For a more bargain level but great mic look at large diaphram dynamics, like the EV RE20 (accoustic chamber minimises proximity effect), Sennheiser MD421 (very useful multisetting HPF), or even the Heil PR30/40. All well under 1k new, 400ish used and very good - all staples in pro studios. There is also the Shure SM7b but that is low sensitivity (requires a ribbon-like amount of gain) and more coloured (Shure signature midrange thing).


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## GoldenSeptimiy (Nov 20, 2021)

As you have already been told, this is 639A. It was a very good microphone.


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