The AM Forum

Was goin' through the W0ZUS stuff today. Found a couple of Shure 55S mics. I understand this is a good mic and I am looking for recommendations on how to best couple it to the transmitter. I'm not very savvy with outboard audio boxes. I know the basics, but I have never used any significant audio processing equipment. The extent of my audio processing to date is using a Heil mic into a W2IHY mic amp/equalizer into the transmitter. If this Shure 55S can be the starting point of some broadcast quality audio I'd like to give it a try. I have gone back through the archives and have looked at much of what has already been discussed, but I'd like to hear some specific suggestions on exactly how to hook up these outboard audio units between the mic and the transmitter. A block diagram would be very helpful.

Thanks, Ron
skipperfam@midco.net

First place to start is the mic itself.  Hi-Z or balanced Lo-Z?

If it is high, you need to go through a pot directly into the grid of the first audio tube in your mixer/preamp.

If it is low, you should run it into a balanced, 50- to 200- Ohm transformer coupled preamp.

From there, on to an EQ if you want, then to a compressor/limiter then into the TX

The 555 is not in any way a bad mic, but it is not a 'broadcast' mic. 

45 years in stations in three countries, never saw one in a control room or studio.  Lots used for remote broadcasts, PA work, and ham stations.

73DG

For a broadcast rig (low Z balanced input?) pretty good audio can be had with a couple of boxes:  Symmetrix 528 (the 528E is what is currently available but I have heard the earlier version is preferable but I can't remember why now) and a broadcast tx peak limiter like an Inovonics 222 or better yet (in my opinion) one of the CRL PMC limiters.  PMC stands for Peak Modulation Controller.  CRL (Circuit Research Labs) made different models over time, the PMC-300, 400 and 450.  I have used the 400 and 450 with good results.   I have not used the 300 but it is certainly functional, i.e. it gets the job done.  What you want is a very fast acting tight peak limiter that will hold your up and down peaks so you can drive it to about 6 dB gain reduction so it sort of functions as a compressor/limiter.  The 528 is not cheap but you get a lot of things in that one box: mic preamp, compressor, basic equalizer maybe something else (noise gate?  can't remember).   Those two boxes are about all you need.  It is important to understand that your garden variety limiter, the boxes sold by guitar shops, and mass market audio vendors is not what you want.  Those limiters are designed for PA systems, live performance, recording...and do not perform with the extremely fast acting peak limiting that you need with a transmitter.   

The old Sure 55S is a PA mic.  It was popular mainly because that is what they stuck in front of Elvis. ITs knows as the elvis mic.  Its switchable from very low impedance 30-60 or  to low impedance 120-150 ohm.  It has a warm mid sound.  Not hi fi like a broad cast mic.  It could certainly work and if you enjoy the look go for it!


Here is all the info you need

http://scottymoore.net/shure55s.html

From radio history:

http://uv201.com/Microphone_Pages/shure_55s.htm

We had one in the perfoming studio at WNGO in Mayfield in the mid-fifties.

Most of the Saturday groups just gathered around it and sang toward it. Not bad, but not RE-20 quality.

Phil

Tried a few. Not something I'd use for over the air. They do look good though.

Maybe they needed a new cartridge or the impedance match was poor. If the 55S was good enough for Elvis it should do well on AM.

Carl

My bet is the match like you said Carl. They are low.  I tried one here. My Voice channel as adjustable impedance. He helped but still. I think it was meant to work with matching gear.

C

I was offered one today, looks almost new but priced a bit high at $125 and working condition unknown. I dont pay Fleabay prices at someones home.

Not my first rodeo.

I prefer 600 horses and a 6 speed ::)

How many telephone books do you sit on in order to see over the dash?

Fully agree with impedance match.
Using some of these mics. in our Ham stuff will present serious mismatch.
I have a Heil Gm-5 and it is very sensitive to impedance match. (plus a peculiar smell in the windscreen) When you have a match, it is a beautiful sound. Rarely needs EQ.

Adolph Hitler used Neuman microphones for his speeches.

The Grateful Dead had a very special application for condenser mics for their performances, with the speakers BEHIND the band members.

http://www.dozin.com/wallofsound/

Fred

I saw the dead at Masonic Temple of Detroit January 21, 1979. This venue is truly a unique place to see a show. http://themasonic.com/index.html the place is a historical marker on its own but the sound is great. The only other venues in Detroit that compare for sound are the Fox Theater and The Detroit Opera House. The Detroit Opera House is the best of all, if you ever come to Detroit it is worth the 10 bucks for the tour truly a jewel http://www.detroitoperahouse.com/doh/about-us/history/ this strays from the mic's but Fred gave me the segue.  Nobody ever says anything nice about Detroit unless you come from here.
John N8QPC

I forgot the best of all http://en.wikipedia.org/wiki/Orchestra_Hall_(Detroit,_Michigan)
http://www.kriegerproducts.com/successstories/historic-detroit-orchestra-hall/

Your getting boring Calhoun, might be time to go behind a closed door and rotate your knob awhile, iffn you can find it.