SE Icis Condenser - Schematic And Photos

[rodabod]

I think I've found the capsule...

It's Peluso's new CEK12. They must have changed it as the screw layout is new:

http://cgi.ebay.co.uk/Microphone-Capsule-for-AKG-C-12-and-Others-CEK12_W0QQitemZ310093454027QQcmdZViewItem?hash=item310093454027&_trksid=p3286.m63.l1177

 

[zebra50]

Hi Roddy - looks right. Even the grey paint is the same.

They're not that new - I picked mine up in about April, used from another forum member on the black market. Those are the ones that I was talking about in the other thread. They sound good.

 

[rodabod]

For reference, a spare single-sided CEK12 from SE is £75 including VAT. I suppose the Peluso double-sided version may be better value if you like the extra patterns.

 

[Rossi]

On thing I keep noticing in Chinese made mics is that the polarization voltage goes to the diaphragm rather than the backplate. Which means the diaphragm will collect dust due to its electrostatic attraction. On a single sided capsule you can usually just swap the leads, unless the backplate is grounded via the capsule mount.

Those two 100nF caps across the output seem fairly large. They may take off some high end (which is probably a good thing) but they will also introduce distortion due to the fact that the load impedance at high frequencies is very low.

The voltages may be too high because they calculated at 220V mains voltage while the nominal EU standard is 230V now. In the UK it may actually be higher than that, maybe 235V - you used to have 240V, right? In Germany it was 220V, the actual voltage at my home is 225V now.

 

[zebra50]

Oh, we still get 240V... and in Yorkshire we're close to power station so sometimes higher (285V once - we called an engineer for that one!)

I think they set the standard to 230V +10%, -6%, which means we can still have 240V, even 250V and be within spec. I like voltage regulators on my tubes for this reason!

 

[rodabod]

Rossi, you make some good points. I thought the capsule wiring was stupid too.

[quote author="Rossi"]Those two 100nF caps across the output seem fairly large. They may take off some high end (which is probably a good thing) but they will also introduce distortion due to the fact that the load impedance at high frequencies is very low.[/quote]

I tried to calculate the filter here, but got lost. I tried seeing what frequency the caps would look like 200R to see where the cut-off was for the filter, but clearly this is wrong. I wouldn't mind implementing it, but would like to change the values. It should be simple, but the numbers I'm getting don't sound correct. Good point about the distortion...

 

[CJ]

Maybe the caps are 100 Pico Farads?

Series makes it 50 pF across the sec.

Maybe a hash filter for a noisy power supply, I don't know.

 

[rodabod]

Re-posting the schematic as requested by someone.