ECM8000 Mods

Flatpicker,

Thank you for posting the clips.
Everyone has his own idiosynracies--I like to start working with low resolution system and work until I cannot hear the difference, so I know where, and how far I went. Then I go to the higher end system. To record these clips I used crapy unmarked cables, and Eurorack MX802 mixer.
I don't play guitar, and as I mentioned before, my baby-grand is out of tune. Today I went to our local GC. The guys there are incredible! I talked to a seller there--plays bass and guitar--and he agreed to help me. This coming Tuesday we have an appointment, and this time I am bringing in the mics, Canare cables, my tube pre, and Alesis Masterlink.
Hopefully by then the capsules are coming as well, so stay tuned Genlemen.

(edited to make things more clear :) )
 
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<Normally pulling things apart doesn't bother me and believe me I've probably gone through more oz/lbs or gms/kgs of solder than half the people on this forum put together, but right now I have other work to complete in the studio and as yet I haven't installed the software that came with my son's new digital camera, so if and when I get around to it, I will show you this third pcb layout.>

That's cool Ausrock. Whenever you have time.... :cool:
 
Marik said:

Dayvel, it is a cool solution. However, aluminum is prone to oxidation, so on the long run it wouldn't be very safe.
I was thinking about phase-splitter (like what Scott Dorsey does in his Chinese mics mod), however, I want to come up with a schematics which could use the existing PCB with some modifications, so the more or less experienced folks here could perform the mod without getting into troubles of etching PCBs and that stuff. And of course, for myself I will make an 'exclusive mod'.



Marik, I've been using the "paper clip" method for a couple years and haven't had any problems with oxidation yet.
I'm using a modification of Scott Dorsey's circuit for a phantom-powered XY I've made. You can see the mic and the circuit at- http://www.mp3forkidz.com/mic/phantxy.html
I've also posted some mp3s, so you can hear it.
 
dayvel-
Nice mic projects. What should I use for project boxes if I don't have bad breath (or if I do and don't care)? :)
 
Thank you Dayvel for posting it. It is a cool idea to use Altoids box. Interesting, I had exactly the same idea to use Scott Dorsey's circuit here, but then dropped it, as I thought it could be pain in the neck for some folks to make a new PC board. I am wondering about your mic sensitivity, as Scott's circuit was designed for LD mics, which have larger output.
According to the graph Horns seem to have better bass response, but I liked Panasonics better. Did the mics have the same placement? Have you tried WM60s as well?
 
Thanks Marik. The Altoids box is pretty standard for the stealth guys, that's where I got the idea. I built the circuit on a piece of RatShak grid type perf board, it's no big deal since you don't have to worry about the gate circuit layout for the FET like in Scott's original circuit.
An electret capsule output is about the same as as a condensor mic, which makes sense, cause they are a condensor mic, just without the polarizing voltage.
Can't use the WM60 for this, you need cardioids for the XY response. By the way, I think the WM61A is a better capsule than the WM60; I don't see why everyone is so bummed the WM60's are going out of production.
Both the Horn and Panasonic capsules had exactly the same placement, I just switched the head out beteween takes. If you look closely at the response graphs, they're almost the same. They both start rolling off about 6dB per octave around 300hz. They sure don't sound the same, though.
Crazydoc, there is no substitute for the Altoid box. They take solder extremely well, and will hold two 9 volt batteries with ease. I don't like Altoids myself, but fortunately my mom loves 'em and saves up the boxes for me.
You can see more Altoid boxes in action at-
http://www.mp3forkidz.com/mic
 
<Can't use the WM60 for this, you need cardioids for the XY response.>

Am I stupid?! Sorry I did not click. Yeah, I was wondering about bass response on the graphs. Now it makes sense.
 
DJL,

Don't worry, I did not forget about this one. The capsules just arrived, so the gutting starts right away. Sorry, I had to call and reschedule today's appointment with that guy, as I have to pick my fianceee from the airport exactly the same time.
 
OK folks,

I just opened both WM60 and WM61 capsules. They have different back chambers, different backplates, and their FETs read respectively 1X:P and 1X:H. It is impossible to do something with WM60 without busting it, however I was able to connect 2SK170 to the WM61. The output was muuuuch lower, what makes me think that the internal FET has much higher transconductance--I did not measure it yet. I connected the capsules to the mic and the WM61 has noticably higher output and lower noise. I did not check the SPL hanling yet. To summarize progress and what we know for today:

1) I found that we have to use stock capsule, modified for different internal FET connection.
2) I found how to make a safe connection to the ground.

Next step--compare the WM60 and WM61 sonics, noise and SPL handling. So, saga continues, Gentlemen.
 
BTW, I forgot to mention... I took the stock capsule off the body of the ECM8000. It looks exactly like WM60. Engraved printing is the same style, same font, size--'60 E 31' on stock, '60 C 21' on Digikey capsule.
 
Some pics.
The WM60 busted. From left to right: diaphragm, glued to ring. The ring also works as a spacer between body and diaphragm, and creates a resonator. Next, spacer (black ring) between diaphragm and backplate. Backplate (WM61 has four holes). Backchamber.
 

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WM61 opened. On the left 2SK170 prepared for installation, on the right original FET on PCB.
 

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WM61 assembled with 2SK170:
 

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Marik said:
Some pics.
The WM60 busted. From left to right: diaphragm, glued to ring. The ring also works as a spacer between body and diaphragm, and creates a resonator. Next, spacer (black ring) between diaphragm and backplate. Backplate (WM61 has four holes). Backchamber.
You mean the backplate (WM61 has three holes) right?
 
<You mean the backplate (WM61 has three holes) right?>

Sorry for being unclear. The picture shows the WM60 back plate, which has 3 holes. The WM61's backplate has 4 holes.
 
Marik said:
OK folks,

2) I found how to make a safe connection to the ground.


So how do you do it, the aspirin-flux-soldering method or did you find a better way?

Great work, Marik. I did get as far as opening capsules, but I never got them back together again.

Another idea: do you think it would be possible to use an external polarization voltage (e.g. 48V phantom power), provided, of course, you take out the internal FET? Perhaps this would improve S/N a bit...

Damn, so far I couldn't find a source for the WM61 capsules in Germany. They sure look very interesting.
 
<So how do you do it, the aspirin-flux-soldering method or did you find a better way?>

I was thinking about aspirin, then desided to drop it, as I am afraid to overheat the body, and destroy the electret. I made pictures how to do it, but the capsule is so tiny that you cannot see anything even on closeups. It is really much easier to see once then to explain, so later tonight I will draw a pic and post it.

<Another idea: do you think it would be possible to use an external polarization voltage (e.g. 48V phantom power), provided, of course, you take out the internal FET? Perhaps this would improve S/N a bit...>

Rossi,

Yes, it is possible, but as far as I know, the electret is precharged to 100V, which is twice as high as phantom power, so you will actually loose gain and as a result S/N.
 
Marik said:
<You mean the backplate (WM61 has three holes) right?>

Sorry for being unclear. The picture shows the WM60 back plate, which has 3 holes. The WM61's backplate has 4 holes.
Thanks Marik. :)
 
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