I bought a O.C. White scissor mic boom for $30 of ebay exactly like this one: 
(or see attachment)
It appears to be in excellent condition. Problem is, I can't figure it out!
If I fold it down it will instantly spring back open with a force that could hurt somebody!
I studied mine against the picture shown at O.C White website and see no differences at all. Everything appears the same, the size and tension appearance of the springs appear no different to mine. I see nothing that looks broke and nothing looks to be missing.
It doesn't make sense to me. I thought these things simply stayed in the position where you move it.. What's going on?
I meant to put the description link, here it is, but it didn't help me..
http://www.ocwhite.com/broadcast-arms/proboomtm-elite-mic-arm-29-reach.html
Does it do this with a microphone attached? It is probably preset to account for the weight of the microphone.
Booms have tension adjustments at the "elbow". After the mic is installed and the boom is mounted to the table tightening or loosening the nuts should bring it into satisfactory operation. Also look for a spring tension adjustment which may need to be made.
Neil
You found a good deal. Now you need one of these if you can find a similar deal, and also a good broadcast mic.
There is nothing wrong with a classic EV RE20, but used or good deals go away very quickly ... because everyone knows it's been a studio standard for many years. They have a flat response so you can taylor EQ for your voice for top modulation, they are dependable dynamic mics-- very rugged and don't require phantom power yet sensitive enough at close range for detail. If you're on the air a lot, I judge them a better choice than most condensers and certainly better than almost all of the USB podcast mics. I'd bet there are stations still using the same RE20's they got 30 years ago
The RE22 has a wee bit better sound, intended for the same basic duty, but IMHO having heard them both, I don't think it's worth the extra $$.
I use a SHURE KSM27 in my studio, which I got for recording, but it's a condenser, too sensitive, picks up every other little sound in the CR.
Another good studio standard is the SHURE SM7, also a dynamic mic. Not as flat a response as the EV RE20, but it's probably second behind it. Lots of people, especially the analog R2R tape people like it for recording as well. Also rugged and dependable.
Another standard choice which you can sometimes find used in good shape or a good deal is the Sennheiser MD-421. They're more known for tom mics (drum kit), but they have 5-position bass control right on the mic, and have also been used in broadcast for a long time.
Any of these will have enough weight to balance your swing arm.
Ken, that mic holder is going to have to wait.. a good while.. I am spent out! I hope the regular shock mount I have will be ok. I also lucked out on a O.C. White riser stand from another seller for a grand total of $16 - it hasn't arrived yet.
I bought two mic's. A NT-1 (I paid $125 for that one), and a MXL 990 ($50), and well as a decktop mic stand.
Those mics your talking about is beyond my budget.. Maybe someday!
By the way, the RE20 is the very mic I originally sought out to find used at a price I could afford, but I had no such luck. Apparently they are considered the golden grail of broadcast microphones.
Niel, thanks for the info, when I install it I'll try messing with the nuts and see if it will adjust.. maybe I need weaker springs.
That danged mic holder costs more than my mic arm!
We have an extremely light-weight microphone on our spring-tension arm, and it works fine. We can pull the mic out for use, adjust it up, down and put it away in the folded position.
For a mic-holder there is an inexpensive Radio Shack holder with a big plastic clip, like a huge clothes-pin, which adjusts to almost any size mic.
If your spring-arm needs more weight you could hang heavy objects in addition to the mic and get it balanced with junk from around the house. You could adapt a large paper-clip as a hanger, use a "netting type bag" that comes with onions or oranges and hang D-cell or other heavy batteries to solve the counter-weight problem.
I hear you Crow, There's also one on ebay for only $10 more shipping.
I wouldn't worry, Rich. Either of your mics should have enough weight, especially if you put a pop screen in front. If you're bank account is like mine this time of year, I can hear it making sucking sounds six blocks away 😉
Both mics mentioned are condensers, so you will need a pop screen ... one solution is to get a needlepoint hoop set and stretch old nylon stocking in it and trim it ... paint black. Then use hangar wire to mount it. If you're careful, you can make a pro job of it.
I found a page for a DIY pop screen:
http://www.jakeludington.com/project_studio/20050321_build_your_own_microphone_pop_screen.html
Ken, I actually got a pop screen coming, but that link was pretty kewwl.. I saved the page, I'll eventually make one for the other mic.
As for the mic holder, cant I just screw the MXL shock mount I have to the mic arm? ( I also have a shock mount coming for the Rode, it's coming from Japan, it was soo much cheaper. I should have it by... someday).
Carl,
If your spring-arm needs more weight you could hang heavy objects in addition to the mic and get it balanced with junk from around the house.
I've got some fruit cake left over from Christmas, can I use that?
Rich, you are super creative to think of a use for the fruit cake. It could work!
And you could occasionally fine-tune it by nibbling.
"As for the mic holder, cant I just screw the MXL shock mount I have to the mic arm?""
Sure ... I don't have a swing arm, just a desktop boom which has been fine for me. Since my mic, like yours, is side-address, so it's mounted upside down, essentially the same way you see them in sound booths. It used to be that they did that with tube mics to keep heat from affecting the components (as opposed to upright-mounted), but it's a good idea anyway, gets the cable out of the way, the boom is higher allowing more room under it, etc. My pop screen clips on the the top of the boom behind the mic's shock mount, hangs in front from its short gooseneck.
I've got a live event coming up where I hope to have room for my bigger studio stand. It will mount several overhead mics. More info, maybe some pix, as the date approaches.
Actually Carl, I ate the rest of it last night! No Joke! Someone gave me a famous Claxton fruit cake at Christmas, and they are rather good (not like those terrible things that it seemed no one particularly wanted to eat when I was a kid). I still had a piece left hiding away in aluminum foil which I stumbled onto last night while looking for cheese, and I ate it!
Carl, ...so it's mounted upside down, essentially the same way you see them in sound booths. It used to be that they did that with tube mics to keep heat from affecting the components
I never knew that. How interesting.
And your catering entertainment to an upcoming event eh? That sound pretty cool to!