ianharpo
12 posts
Aug 27, 2010
5:34 AM
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I found an old 50's element which fits snuggly in my blues blaster but it has a really really low output - I've read an advert or two from the Mic vendors that say "I've added a transformer to the element converting it to Hi Z"......now what I wanna know is what exactly is this piece of electronic wizardry that'll fit inside a mic shell??
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N.O.D.
131 posts
Aug 27, 2010
5:49 AM
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www.mouser.com /// Exicon mini transformers part # 42TM117-RC or 42TM017-RC
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Cheers big ears#
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ianharpo
13 posts
Aug 27, 2010
6:38 AM
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Thanks a lot Buddy. There are 6 pins though, any clues as to what goes where??
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jbone
384 posts
Aug 27, 2010
4:45 PM
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greg heumann is the resident wizard on things of this nature. he installed an internal transformer in a military-issue e-v m43u for me along with a volume pot, and it works beautifully with my tube amps large or small. this mic was originally a low z with a difficult connector even for use in a standard p.a. greg changed all that by adding a screw-on connector.
i have no doubt he can get you going in the right direction.
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Joe_L
574 posts
Aug 27, 2010
5:27 PM
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+1 on Greg! He's awesome.
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ianharpo
15 posts
Aug 31, 2010
2:38 AM
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So, anyone got a schematic for doing this?
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N.O.D.
149 posts
Aug 31, 2010
2:58 AM
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Bro i was hopeing for a joint answer check out the PDF Data file provided on the page
have you got a multi meter you will find one side of the transformer has a low input ohms reading, the other has high out put ohms reading
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Cheers
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ianharpo
16 posts
Aug 31, 2010
10:54 AM
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Yep I've looked at the data file and I'll have no trouble discovering which side of the unit is low and which is high.........the question is where do each of the 6 pins get soldered to on the guts of the mic?
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Greg Heumann
752 posts
Aug 31, 2010
6:10 PM
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Hold on hold on, hold on. You never even identified the element, let alone whether it was low or high impedance. An impedance matching transformer is only useful if you have a low impedance element and want to play it straight into your amp.
SO - if the element in your BluesBlaster is its original Astatic MC-151 crystal, and its output is low, it is because the crystal is terminal and already near death. No transformer is going to revive it. This is the most likely explanation for what you're experiencing.
IF someone put a low impedance replacement element (at which point it would be a dynamic element of some sort - there is no such thing as a low impedance crystal) THEN a transformer will help.
And unless I know what transformer you have I can't tell you how to wire it. I doubt I'm familiar with it if you bought the one NOD recommended, he can probably help. Alternatively, download the data sheet for it from Mouser - the schematic is right there.
If it is a Shure transformer (as found inside their A95/U impedance matching transformer product) then it has 5 wires. Red and black are the high impedance connections. Green is the "plus" low impedance connection. Yellow is the 150 ohm low impedance "minus" connection, and orange is the 15 ohm low impedance "minus" connection.
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/Greg
Last Edited by on Aug 31, 2010 6:16 PM
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ianharpo
18 posts
Sep 01, 2010
2:49 AM
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Hey Greg thanks for chipping in. The original crystal element died and I picked up form a stateside flea market an element which is rather heavy in weight but which fits the JT30 gasket perfectly. The guy told me it was from the 50's NOS most probably an earpiece from a military headset (he had a store full of military stuff). I've wired it in but with the volume fully up on the mic and amp & I can only just get a very quiet noise out of it.
My OP asked for where I could get hold of a suitable tranformer to whack up the output. I havent put a meter across the element but the output I'm sure will be very low. You seem to suggest that the output would need to be "matched" by the input of the transformer if I've understood correctly....can you elaborate? I've not bought the transformer NOD recommended yet
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Silvertone
41 posts
Sep 01, 2010
4:48 AM
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Ianharpo it sounds as if you may have an earpice speaker,if that is the case a impedance transformer more than likely will not help.
Slightly off topic but in the spirit of clarification, an impedance transformer can be used backwards. Ive never needed it but it can allow you to play a hi-imp bullet thru a pa w/out a hi imp connection,plug your bullet into a stage mic line at your local jam or as Shure states to us a longer cord.
From the Shure website;
The Shure A95U is a reversible transformer that matches low- or high-impedance microphones to high- or low-impedance inputs. The transformer permits use of very long microphone cables with high-impedance microphones. However, when connecting a high-impedance microphone, limit the cable length between the microphone and the transformer to 4.6 m (15 foot). The cable from the transformer to the low-impedance input can be any desired length. The transformer prevents high-frequency loss, level loss, and pickup of noise and hum.
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ianharpo
20 posts
Sep 01, 2010
5:48 AM
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@ Silvertone......it's not well known but a speaker is the same mechanically as a mic and so the fact it may be an earpiece is unlikely to make any difference at all.
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MJ
177 posts
Sep 01, 2010
8:04 AM
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@ianharper..Here is a link with minimal stats on a few military type headset speakers and mics. If you have a speaker from one of these headsets it may be true that it can be used as a mic, but only has 1 ohm impedance. W
http://www.milspec.ca/radaccs/raccspec.html#h251
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Greg Heumann
754 posts
Sep 01, 2010
8:32 AM
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Agree with Silvertone. If MJ is right and the impedance is 1 ohm, you'll need a transformer with in-to-out impedance ration of 10,000 to 1, 100,000 to 1 would be better. None of the ones NOD pointed you to come close to that. I don't know if they exist - they might.
If I were you I would simply chalk it up to a loss and use a known element. A good CR, CM or Crystal will give you good results. They're available - I have them as do others. If you're interested contact me off line.
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/Greg
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ianharpo
21 posts
Sep 01, 2010
11:46 AM
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Thanks Greg..........I just measured the resistance across the two poles and when the meter is set on 200 the element gives a reading of 90 - Does that tie in with "too low an output to transform up" ???
Last Edited by on Sep 01, 2010 11:47 AM
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rharley5652
222 posts
Sep 01, 2010
3:04 PM
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90ohms,. you should be able to use a transformer with good results if it's a dynamic ,.but with out seeing the element you may be getting 90 ohms outta a crystal or ceramic element ,.in witch case its dead or damn neer !
A crystal or ceramic you can not use a transformer on as noted above ,.. My advice is get a High Z CM ,.even a Low Z CM then wire in the transformer to make it High Z,.
I have both high & low if needed,.just send me a message through my link below .
Good luck
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Simply Unique Kustom Mic's By Rharley
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Greg Heumann
757 posts
Sep 01, 2010
5:57 PM
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If it is a carbon earpiece from military headphones, all bets are off.
Resistance does not equal impedance - however for KNOWN elements it gives a clue. If this were a Shure CM then it would be a low impedance element and a transformer may well help.
You really can't hurt the element by hooking it up wrong to any sort of passive components like transformers between the mic and the amp. Sometimes you just have to experiment.
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/Greg
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rharley5652
223 posts
Sep 01, 2010
11:32 PM
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Yes ,.yes forgot about the carbon elements ,.as said ,.all bets are off.
Ianharpo,.Post a picture of it if ya can,.. so we can see what ya got there ??
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Simply Unique Kustom Mic's By Rharley
Last Edited by on Sep 01, 2010 11:32 PM
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ianharpo
24 posts
Sep 02, 2010
9:00 AM
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Seems to be too heavy for a carbon element
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Greg Heumann
760 posts
Sep 02, 2010
2:45 PM
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I don't recognize it. The front looks very crystal-ish. However there'd be no need for the upper cover on the rear, which suggests dynamic. The fact that you measured 90 ohms across the terminals pretty much insists that that is a dynamic element. It WILL work better with a transformer.
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/Greg
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ianharpo
25 posts
Sep 02, 2010
11:31 PM
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Ok Thanks for the ID greg...........now where do I get me one of those and how do I wire it into the schem of things in the Blues blaster. Like I say I've already removed the old dead one.
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rharley5652
224 posts
Sep 03, 2010
12:19 AM
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@ Ianharpo,.crystal-ish indeed,..here's few pic of an Astatic Crystal with the can on it,.
Does the can on the back of yours com off or is it part of the element?
As I have never seen one like this either ,.hard to tell what it is ??
Bottom pick shows the Astatic is putting out 2.49 meg ohms and has very low audio,.
Best you can do is hook up the transformer to it,.
an see what it does ,..
Can't hurt as you have no way to know if it's carbon ,dynamic,crystal,ceramic,.
If the can comes off maybe we could tell more?
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Simply Unique Kustom Mic's By Rharley
Last Edited by on Jan 09, 2011 12:30 AM
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ianharpo
27 posts
Sep 04, 2010
7:50 AM
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I took a closer look this morning. The "can" but it attached (moulded) and will not detach from the rest of the aluminium back...........looks like the mic "opens" only if I was to uncrimp the black holed metal grill which is bent around the backhs....and it resists any attempt to unbend it! It's really solid.
Anywayhoo.....lets assume it is dynamic then, what tranny would be suitable and how would I wire that in?
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ianharpo
39 posts
Sep 09, 2010
3:05 AM
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........can I get some love on what transformer would be suitable and how to wire it up then?
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N.O.D.
177 posts
Sep 09, 2010
4:02 AM
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Bro if the element you have looks anything like the one above no transformer is going to be of use to you,
You say the element you have is Heavy:(
Heavy element Heavy microphone holding it for a long time you will get Hand Cramps:(
The transformers above from mouser come with wire pins there for PC cercuit boards, or come with wires for Audio aplications
check out mouser part 25M-032
to go with one of them Transformers:)
About them Ebay Vendors you can ask one very Helpful vendor who is willing to help you out with the exact info you want you only Have to ask Him:)
Technobird tell him Scruffyk9 sent you his way:)
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sorry no love
and a tight cup:)
Last Edited by on Sep 09, 2010 4:03 AM
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joshnat
73 posts
Oct 25, 2010
12:10 PM
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Resurrecting an old thread:
Mouser 42TM117-RC seems to be 1K to 50K and
Mouser 42TM117-RC seems to be 600 to 25K.
Does it matter which transformer is used for a typical low impedance element, as long as the ratio from low to high is big enough? I want to make some XLR-1/4 adapter/transformers with pigtails, and it's way cheaper to do it myself than to buy them pre-made. Also, I have a Shure PE57SB I'd like to put back together with a transformer and volume control for HiZ.
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markdc70
41 posts
Oct 26, 2010
8:09 AM
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Heres a question I'd like answered. Now I know when connecting a mic, pedal, or the output of anything electronic into a second electronic device, that you want the input impedance of the second device to be at least 10 times the output impedance of your first device. (Am I close to being correct about this?) Now from the specs of these low to hi z transformers, this doesn't seem to be the case. For these, do you try to get a transformer with a low z winding that somewhat closely matches the mic element impedance? Also, the frequency response of those transormers NOD mentioned seems to be lacking the low end for harp mics. So Dog, do your mics still have a low end growl with one of these transformers? ;>)
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Greg Heumann
827 posts
Oct 26, 2010
8:41 PM
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yup, that's an Astatic crystal. Cool - I've never seen one with that can on the back before. No transformer will help - give the element a fond burial and move on.
@Markdc - the impedance of the transformer itself doesn't matter so much as the multiplication factor - i.e., the ratio of input to output.
A really easy, cheap way to get a single transformer of the right value is to simply buy an off-the-shelf impedance matching transformer made for mics. The engineers have already chosen the right transformer for you - just open it up and gut it. You can get an Audio-Technica IMT for $10 from Amazon or elsewhere.
@Joshnat Yes, you can buy an XLR cable connector, a transformer, and a 1/4" male connector for a little less, and scrounge some cable somewhere. It won't have cable molded into the connectors for long life like the commercial ones, so better get yourself some shrink wrap and pay attention to strain relief. If you LIKE doing that sort of thing, go for it. On the other hand, you can buy an Audix T-50 (an IMT with a pigtail) for $25. Is it really worth it?
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/Greg
Last Edited by on Oct 26, 2010 8:43 PM
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rharley5652
246 posts
Oct 27, 2010
2:02 PM
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@ Greg ,...yup, that's an Astatic crystal. Cool
That is the only Aststic I have that came with the can attached,.to bad it's a weak sounder,..like ya said an I agree ,.put a CM in that blues blaster an call it a day.
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Simply Unique Kustom Mic's By Rharley
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Mojokane
118 posts
Oct 28, 2010
11:57 PM
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this may not be necessary now, but someday we'll be scrounging up the low Z's, too. (Start collecting em now..)
I actually have a handful waitin already.
..black & white CR's, CM's...you know what I'm talkin about...try this idea.
What would it take to have a jack (at the amp), specially rigged with a tranny? Matching the neccessary resistance from mic to tranny?
And what sort of problems might one encounter. eg; cable length?, xlr to 1/4". etc..?
Out of laziness, how hard would it be to do this with a standard type, bought at RadioShack?
I don't need this feature now, for sure, though.. maybe later, much later.
What say you?
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rharley5652
248 posts
Oct 29, 2010
1:04 AM
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Mojo Kane ,...Man I know your work A+A+A+ ,..ya know ya got all that figured out already ,.LOL
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Simply Unique Kustom Mic's By Rharley
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Mojokane
121 posts
Oct 29, 2010
3:09 AM
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howzit!?..your too kind, Ron. You're sorta right.
..how's biz? I've owned a couple alterd low z elements before. But never actually did the work my self. All those wires! It's a little intimidating.
Alot like the Calrad Dynamic D.T.51 microphone cartridge w/transformer(50,000ohm) wires, too.
I still haven't taken the time to solder them correctly. What a retard! I ruined two already. I have a shit load and hope one day they'll come in handy..
Are they any good for harp?
Keep on jammin!
K
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Greg Heumann
832 posts
Oct 29, 2010
8:13 AM
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Hey, Kevin -
All those wires? Only 4 on a transformer that matter - 2 in and two out. You COULD put the transformer inside the amp. You could do a lot of things. You could replace the amp's jack with a stereo one and wire the cable in balanced mode (i.e. like standard low impedance cables) and you could have 100' cable lengths with virtually no signal loss! Or you could just throw a transformer inside the mic itself and leave everything else alone.....
Cheers!
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/Greg
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Mojokane
123 posts
Oct 29, 2010
10:26 AM
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Greetings, Greg -
hmmmmmmmmmm...you know me..always lookin for a ways to do things more efficiently. You make a good point.
"leave everything else alone.", sounds a lot easier.
This thread sure addresses all the issues with tranformers...thanks, everyone! for throwin your 2 cents in.
I brought up hard wiring a tranny after hearing about Torres' 59 Bassman clone chassis with custom voiced input jacks for different elements (crystal, dynamic, CM & CR's...and I was thinking what to do with the last (4th hole) jack. Not that I'm thinking of buyin one. I have enough, and I may be selling off some stuff here soon. I need the moola more. You can't eat your gear. And space is a valuable commodity these days.
aloja,
K
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joshnat
75 posts
Oct 29, 2010
12:26 PM
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@Greg: Actually, I do like doing that kind of thing! It helps me understand how the stuff works so I can (try to) fix it if it breaks. Plus, I just like making stuff.
The Mouser transformers I mentioned above increase the impedance between 40-50 times. I assume that's enough for most applications?
As for wiring one into the input of the amp, I did that last week. I have an old Roland keyboard Cube amp that only has two high Z inputs, so I replaced one with an XLR and transformer so it could be used with a vocal mic and cable. Success! Not really, the amp's not working at all now. Don't know what I did, but I did something!
Maybe my ex-wife was onto something when she used to call me Mr. Fixit.
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