6SN7
452 posts
Aug 13, 2014
6:02 PM
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I was checking a couple of my mics lately and wanted to ask a few questions that maybe someone here at the forum can answer. I read the stuff at Green Bullet mics, but I am still confused, so here we go...
I have Black CR 99A86-950. Its awesome and my go to mic.
I have a Black CR # 99E86 - 333 and a Black CR #99H86 - 346.
What's all the serial number mean. Are the A's better than the E or H ones?
Any additonal info would be appreciated. Thanks in advance
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SuperBee
2159 posts
Aug 13, 2014
6:33 PM
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From memory the diff between A, B, G and H is pretty much just the letter printed on them. I think I read it indicates the destination rather than any difference in manufacture. E though I think designates an actual difference...have you measured the impedance?
Last Edited by SuperBee on Aug 13, 2014 6:34 PM
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6SN7
453 posts
Aug 13, 2014
7:34 PM
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Measure impedance, no I wouldn't know how to do that. I understand the "E" is medium impedance according to the Grees Bullet Mic website.
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SuperBee
2160 posts
Aug 13, 2014
9:15 PM
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That's what I thought. As I understand it, G and H are the same as A and B, as in a G is an A with G stamped on it instead of A, and the same relationship between B and H.
I do not know the difference between A and B though.
Whatever, A, B, G and H are all interchangeable and potentially great elements. E needs an impedance transformer for hiZ use.
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Barley Nectar
482 posts
Aug 13, 2014
10:12 PM
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Medium impedance elements may work very nicely as is, without the transformer. The impedance is the AC resistance that the coil is wound to. More windings make higher impedance/resistance. The higher the impedance, the hotter the output of the element. Many folks buy a hot element than lessen the gain of the amp with tube changes, to lessen feedback. With a lower impedance element you don't have to lessen gain in the amp because you are hitting the amp with less signal. So, if you were to use a medium impedance element in a high gain amp such as a Super Reverb or a Twin say, that element may work just dandy. The only difference will be the volume knob will be on 6-7 rather then 2. Also the medium impedance elements go for considerably less money. Plus you don't have to go find lower gain tubes for your amp. See what is going on here. It all depends on the amp/mic/speaker combination being used. It all works together...BN
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6SN7
454 posts
Aug 14, 2014
4:54 AM
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What would a transformer on a medium impedance element look like?
Is it a diode looking thing?
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Bilzharp
3 posts
Aug 14, 2014
8:25 AM
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I'm with Barley, you probably don't need a transformer with a medium-z element. (Z is the electrical abbreviation for impedance). A low-z element is another story. No, a transformer doesn't look like a diode. It's a stack of steel laminations with very fine wire wound through them. The ones used in harp mics are the size of a small thumb and have at least four insulated wires coming out of them. The ones you usually find on ebay are for low-z though, and don't work well with a medium-z element.
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BluesJacketman
200 posts
Aug 14, 2014
10:37 AM
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Harpmicshop.com has medium Z to high Z transformers.
I had a medium Z CM in a bullet and didn't like it that much.
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Greg Heumann
2802 posts
Aug 14, 2014
8:23 PM
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If you have a guitar amp that isn't set up for harp in the first place then a medium impedance element might be a solution. If you already have a good harp amp, it just sucks. Its too weak without a transformer and too hot with one. Just sayin'
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
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6SN7
457 posts
Aug 15, 2014
5:16 AM
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Thank you for all weighing in. And Grasshopper wants to thank Master Po for weighing in on the final comment. That particular element works exactly as you said. I bought it as a Black CR and it is woeful compared to others. Buyers beware!
Next week, it's on to the White Label CM's!
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chromaticblues
1600 posts
Aug 16, 2014
7:09 AM
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Greg what you said isn't always true. What Barley touched on does happen some time. If you have an amp that came from the factory with 12ay7 in the front and a 12au7 driver. You could put 12ax7's in all sockets and possibly have a very useable situation.
You can also make minor circuit changes to boost gain, but yeah like Greg said why go through all that crap when you can just buy a high-z.
@6sn7 That mic isn't a total lose.
I have a shit load of parts lying around.
I could probably fix it for you.
If interested Email me.
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6SN7
466 posts
Aug 16, 2014
7:38 AM
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Thanks Kevin, I might just do that.
I am begining to realize that I just have a few bad apple black CR's.
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Greg Heumann
2806 posts
Aug 16, 2014
8:54 AM
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I would never set up an amp for one mic that will make it suck with any other mic I use. I want all of my mics' outputs to match within a number or so on the amp's volume control.
I'm sure there IS an appropriate transformer to boost a 99E86 to the right level but I haven't ever done the experimentation to identify one - and I just prefer to avoid the medium impedance elements altogether.
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
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Bilzharp
5 posts
Aug 16, 2014
9:34 AM
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"I am begining to realize that I just have a few bad apple black CR's. "
I've got 3 or 4 black and white CRs that the spindle pin has become decoupled from the diaphragm. The CRs used a little aluminum cap glued(?) at the center of the diaphragm and I think the glue just crumbles after a while. Results in either a low or intermittent output. The little blob of glue used on the CM elements (with no cap) actually seems to hold up better but maybe that's just cuz they're not as old. I've been holding on to my bad ones in hopes that Chuck Gurney would get back into repairing them but I may wind up just super gluing them myself and align the spindle as best I can. Anybody else around that repairs these elements?
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BluesJacketman
203 posts
Aug 16, 2014
9:51 AM
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@ blizharp I have heard of a guy who can. I cannot vouch for his work but it might be worthwhile to contact him. Heres the facebook page:
https://www.facebook.com/HamsammichMics
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