Where is the item located pcrecord ?

Worst case scenario maybe someone else can pick it up for you and forward it on if you cannot source another from somewhere...

PM me the link and I'll see if I can get it for you (y)

Is this it?...pic looks the same.

http://www.ebay.com…

I sent them a massage asking if they would ship it my way...happy to forward it on to you if that is the only way and they will ship it to Oz.

I'll PM you their answer once I hear back.

Marco - I'm a bit confused about your reported experience with the microphone kit. When you said the first one did not work, in what way did it not work? Then the second circuit board behaved in an identical fashion, is that right? I'm guessing you moved the transformer from the first to the second board. Does that mean you suspect you have a faulty transformer, hence your need to get another one?

Is the transformer in your photo and Sean linked to on Ebay the same as the one that Microphone Parts incorporate into their designs? M-P seem to emphasise the "custom wound" credentials of their part, so it would be surprising if it were available to anyone.

After a bit of research the transformer in the kit is a cinemag CM-2461
The photo I put was the one from eBay as an exemple only.

I did the build and it didn't work. All the test points ended with a 10th of the power it's suppose to read.
Matt from microphone-parts was extreemely patient and we exchanged more than 20 emails trying to diagnose the behaviour.
I end up ordering him another circuit but without the transformer.. We thought that I might have overheated a part and we couldn't pin point which.
I did build the new circuit with the original transformer and got the same result.. So I now want to replace the transformer before I throw everything out of the window ;)

Seriously, I may resorb to use the capsule alone in my Studio project mic if I can't get the kit working, but I want to give a it shot with a new transformer first.

Any places where I can buy a cinemag from canada ?

Sean G, post: 438574, member: 49362 wrote: I sent them a massage asking if they would ship it my way...happy to forward it on to you if that is the only way and they will ship it to Oz.

Thanks for the offer Sean, I'm just not sure if it would be an equivalent to the cinemag..

I just sent an email to Cinemag directly and ask where to buy.. I might have a better chance that way ;)

If there's anything I can do to help let me know. Your welcome to use my adress over here in US, for forwarding or watever, or I could forward it to you, whatever it is, I'd be happy to help.

pcrecord, post: 438576, member: 46460 wrote: After a bit of research the transformer in the kit is a cinemag CM-2461
The photo I put was the one from eBay as an exemple only.

I did the build and it didn't work. All the test points ended with a 10th of the power it's suppose to read.
Matt from microphone-parts was extreemely patient and we exchanged more than 20 emails trying to diagnose the behaviour.
I end up ordering him another circuit but without the transformer.. We thought that I might have overheated a part and we couldn't pin point which.
I did build the new circuit with the original transformer and got the same result.. So I now want to replace the transformer before I throw everything out of the window ;)

Seriously, I may resorb to use the capsule alone in my Studio project mic if I can't get the kit working, but I want to give a it shot with a new transformer first.

Any places where I can buy a cinemag from canada ?

Thanks for the offer Sean, I'm just not sure if it would be an equivalent to the cinemag..

No worries Marco, I was only going off the pic as when I put the details into google, that was one of first things that popped up.

You are very kind guys ! Thanks.
Cinemag offered to deliver it to me.. (127USD + 25$freight)
I'm checking if I can get a better price but it seems honest so far.

I'm obviously just getting into electronic componentry, but 125$ sounds in line with my limited experience. Brand name transformers are usually an extra 1-200$ whenever companies offer them as an option. I'm kinda excited to see how everything turns out Marco. You just might have a 'happy accident' on your hands.!!

kmetal, post: 438587, member: 37533 wrote: You just might have a 'happy accident' on your hands.!!

I'd be delighted if it turns out working fine after this last attempt.
Thanks for your support !

Good news my friends ! The mic is working fine with a new transformer. Dawm if I knew it was it I would have save ordering a second circuit...
But anyway, since I have an extra circuit, I ordered all the other parts to build their T12 kit. So, I'll get two mics with same electronics but different capsule (RK47 and RK12)
Matt gave me a good rebate on the extra parts..

BTW the mic sound very good, I'll do some tests and share the results very soon ;)

So it was a faulty transformer then?

Cinemag is far from rare in the XFO world; and their various models are very common in mics, pre's and other hardware processors; but, I suspect that like any company, occasionaly a lemon or two can slip past QC from time to time.

I'm glad you got it resolved Marco, and looking forward to your thoughts on the new mic you've built - and - wink wink - it would be cool to eventually hear some samples of the mic in action. ;) ;)

Man that's great to hear Marco!!! Now you can try both, and your only one capsule away from a pair. Between the focusrite and cinemag stories, you've had some strange situations with otherwise reputatable companies, albeit the interface not necessarily the mantufactuers fault. The upside, is you probably know way more about mic design from all your troubleshooting, than you would if the thing just worked right away. I'm happy you finally got it going man, without having to use the "mic meets wall" effect.

kmetal, post: 439118, member: 37533 wrote: I'm happy you finally got it going man, without having to use the "mic meets wall" effect.

:mad:

:LOL::LOL::LOL:

Actually the transformer I got from microphone-parts.com didn't have any branding. Matt assured me it was more effective than the cinemag in his circuit. That's why I bought a second one from him and discovered the first one was defective.
I can't hold it against Matt because the transformer was reading the right resistance on the tester. I guess it was a magnetic or induction problem.. (really not an expert)

Thanks for the moral support guys !! :)

I'm curious about the magnetic induction, and how it effects or defects operation. Just for my knowledge. Maybe boz will chime in.

Yes, interesting, Marco. I've de-gaussed microphone transformers from both pre-amps and large-format studio mixers that have managed to get themselves magnetised through faults in that channel's phantom-power circuit.

It's a matter of setting up a saturating level of sinewave current through the transformer primary which you then reduce smoothly and linearly to near-zero level over a timescale of a few seconds. Depending on the design of transformer, you may be able to use line-level drive or you may need a power amp for this job. I usually load the secondary with 600 Ohm and view the output on a scope to check for a suitable level of saturation. The sinewave frequency is not important; 50Hz is fine.

I remember going into one studio and seeing strips of bright red sticky tape over many channels of their 32-channel desk. "We don't use those channels" I was told. I managed to get out of them that they had had some problem cables between the control room and one of the live rooms, and that's probably what had caused the troubles. I persuaded them to let me take one of the channel strips away with me. I brought it back a few days later with the transformer de-gaussed. I couldn't test the strip while I had it, but they plugged it back into the desk and it worked fine, so I got to work on the others in turn. It turned out I was a bit lucky with that first one, since only two of the other faulty channels had the same problem. However, it meant it was easy to get them three more working channels without their spending large amounts of money on significant repairs to the desk or losing much studio time.

Boz if you ever write a book I would like an autographed copy. I'll frame it, and use another copy for reference. :)

I must admit you lost me there Boswell, I never De-gaussed a transformer.. ;)
It's amazing to see how many electronics circuits are in our lives and most of us have no idea how they work.. You are Lucky to know that much Bos.
Imagine how much time it would take to start everything from scratch... How many years would it take to produce a computer CPU again ?

Not really. It's just that after nearly 50 years in the profession, I've seen a lot of things, but the problem is remembering them all. It's threads like this that jog those memories, and they come tumbling out.

De-gaussing your faulty mic transformer is worth a try, Marco. Seeing as it's specifically a microphone-level transformer, you can probably use a line-level drive. You could try connecting it up with a line-level output driving the secondary and connecting the primary to a line-level input on your interface (you will need a gain appropriate for the turns ratio). Output a good-quality sinewave at low level and look at the incoming signal. Wind the sinewave level up slowly and check whether you can see flattening of the tops of either the positive or negative excursion of the input signal, as a magnetised transformer is inherently asymmetrical in this respect. Increase the amplitude to see if you can get both peaks reasonably flat. After that, take the sinewave amplitude down slowly to at least 60dB below the peak without switching ranges. Then try the transformer the right way round with a dynamic microphone on the primary and connecting the secondary to a DI input on the interface so it's feeding a high impedance. You'll need to use a fair amount of gain, but you should have enough to see if the degaussing has made any difference to the performance of the transformer. Come to think of it, it's worth doing the mic -> trafo -> DI test before you start the degaussing, then you will have a better start point for comparison.

Boswell, would a wand style tape-head demagnetizer be strong enough to demagnetize a small mic transformer? Or maybe a larger degausser, like you would use to bulk erase tapes?

The design of the flux circuit within a good-quality microphone transformer is very tight, both to get maximum coupling of the available signal and to keep external fields out. Although these transformers can pick up hum if exposed to external mains magnetic fields, the coupling from such a field is small, and my feeling is that it would be difficult to achieve the core saturation needed for degaussing simply by applying an external field.

Tape heads, by contrast, are open magnetic circuits, with the tape oxide forming the missing section, and are therefore designed to be very susceptible to a close applied field.

You could think of the technique I described to degauss a microphone transformer as similar to the use of a tape head demagnetiser, but using current flowing through the wiring that is already present in the transformer to perform the action of taking the core round decreasing hysteresis loops instead of using an external solenoid.

Boswell, post: 439173, member: 29034 wrote: The design of the flux circuit within a good-quality microphone transformer is very tight, both to get maximum coupling of the available signal and to keep external fields out. Although these transformers can pick up hum if exposed to external mains magnetic fields, the coupling from such a field is small, and my feeling is that it would be difficult to achieve the core saturation needed for degaussing simply by applying an external field.

Tape heads, by contrast, are open magnetic circuits, with the tape oxide forming the missing section, and are therefore designed to be very susceptible to a close applied field.

You could think of the technique I described to degauss a microphone transformer as similar to the use of a tape head demagnetiser, but using current flowing through the wiring that is already present in the transformer to perform the action of taking the core round decreasing hysteresis loops instead of using an external solenoid.

I have a warning. Before you go near a mike input transformer with a bulk tape degausser, terminate both the primary and secondary with resistors (1/2 w or so). Unterminated, the strong field from the degausser may generate high voltage in both windings, the secondary in particular, and perhaps puncture the insulation, ruining the transformer. (This was a documented problem with tube input transformers and transients when phantom power was hard switched on and off.) Never turn a degausser on or off near the transformer.

Most input transformers are hermetically sealed and a degausser may not work (i.e. core saturation). Anyone tried connecting the input transformer backward, terminate the primary with a resistor, and feed the secondary with 60Hz audio at a modest level (like +20 dbm) for a few minutes, and retest response and clipping level?

Excellent information gentlemen, thank you both. Luckily I have no need to try either, just thinking out loud - having no idea of the relative strengths of the magnetic fields involved, and wondering if these old relics might ever serve any purpose again.

Awesome info, I'm saving this thread to pdf for my personal references. Who knows when it'll be needed. Great info.

dvdhawk, post: 439182, member: 36047 wrote: Excellent information gentlemen, thank you both. Luckily I have no need to try either, just thinking out loud - having no idea of the relative strengths of the magnetic fields involved, and wondering if these old relics might ever serve any purpose again.

Input and isolation transformer use is alive and well, although the transformers these days are expensive. Many "tough dog" RF or ground loop problems can be cleared using a transformer. Many broadcast audio consoles sold for use at co-located studio/transmitter sites are equipped with transformers on input and output to keep RF out of the active components. Sound systems... Ground loop problems can often be cleared with a transformer, especially with non-isolated direct inputs on the console. A transformer may be the easiest fix for those running older equipment with unbalanced output into a modern board with balanced only inputs. The last situation would be sound system RF interference where the local radio station, CB, or other interference is coupled in to the sound system over speaker and/or mic cables and demodulated in the equipment for all to hear. This is the well known case of "audio rectification" known for years to us in the EMI/EMC businesses. "Tough dog" interference problems can be solved by isolation and judicious filtering or bypassing to interrupt or block the RF path to the amplifiers or other "vulnerable" equipment. For example, f your church is located along US 30 here in PA, or any nearby heavily travelled highway, the minister may appreciate not hearing "Break 19, I'm looking for commercial.." in the middle of the sermon...

As for the transformers, the magnetic field in input transformers is low. Do not allow any DC in the primary or secondary of input transformers from defective phantom powering, leaky capacitors, etc. to saturate the core. The only location where a sizeable magnetic field is found in a audio transformer is the single ended tube/transistor output transformer. The core is typically gapped to break the high, steady magnetic field (may be on the order of one tesla at the gap), caused by the constant DC current to the anode of the tube. Just my $0.02 worth..

Another excellent post, but to be clear, by "relics", I was referring to the wand style head demagnetizer, the bulk tape eraser that have been gathering dust in the basement for almost 20 years.

dvdhawk, post: 439195, member: 36047 wrote: Another excellent post, but to be clear, by "relics", I was referring to the wand style head demagnetizer, the bulk tape eraser that have been gathering dust in the basement for almost 20 years.

Been a while since I rolled analog tape. The last "roll" was from analog to the CD-R. The bulk tape eraser is in a cabinet along with the head demagnetizer.

dvdhawk, post: 439195, member: 36047 wrote: nother excellent post, but to be clear, by "relics", I was referring to the wand style head demagnetizer, the bulk tape eraser that have been gathering dust in the basement for almost 20 years.

I thought you were talking about us. LOL.

rmburrow, post: 439190, member: 46233 wrote: Ground loop problems can often be cleared with a transformer,

Excellent information fellas, I will continue to lurk hear from couch potato studios, but I do have one question. How/why do Transformers eliminate ground loop problems?

kmetal, post: 439227, member: 37533 wrote: How/why do Transformers eliminate ground loop problems?

A multimeter would show no electrical connectivity between the primary and secondary windings of a transformer. If you place a transformer between two pieces of audio equipment, there can be no circulating ground current.

Think of a transformer-input pre-amp - the 48V phantom power isolation is done by the transformer without having to use coupling capacitors.

Interesting, that makes sense. Thanks for cluing me in on that I've been wondering for a while.