Cad Equitek E100 Capsule

[k brown]

I meant to mention this much earlier - I can verify that indeed the Crown CM700 did contain the Primo EM21. I doubt very many owners realized that they actually had an interchangeable-capsule mic. The Primo was completely disguised by a black ring that screwed over it. One had only to unscrew this ring, unscrew the EM21, and screw on an EM23 to make it an omni.

The things are hard to come by these days - hardly ever show up on eBay; mine's gone dead and I can't figure out why.

 

[k brown]

Hi thanks for the tips.
Old PCB is closed case, it's just too damaged.
I've ordered Schopes circuit for electret and will try to see how it will work with stock capsule, if something goes wrong I always can order good old TSB2555B / JLI-2555BXZ3-GP Cardioid Electret Capsule and somehow fit it. Those have been proved and tested many times...cheap too.

This one's much better than the Transound/JLI - about the same amount of top rise as the 2555B, but smoother overall and much better made; machined brass body and gold-sputtered diaphragm, not aluminum (brought to our attention by kingkorg):
https://www.ebay.com/itm/3045989104...Hhnrwzmj02gTnpOLIymakyCw==|tkp:Bk9SR6a5gY-eYQ
Or, this one if you want a flat top response (handle with care - no mesh over the diaphragm):
https://www.ebay.com/itm/255415516289

 

[multiperc]

I bought over 10 similar mics with EM21 last year. Random and untested, none of them had a problem with it.

Since these mics often lie unused for over 30 years in some drawer, it sometimes happens that the batteries leak or the rubber spacers of these become brittle. But all this does not affect the capsules, mine all work without problems.

Poking around here in search of an EM-21 capsule replace the same in my otherwise good 1992 CAD E-100 (original semi-topic this thread). Any interest in selling one of the mics, or better, just the EM21 capsule?

 

[rock soderstrom]

Poking around here in search of an EM-21 capsule replace the same in my otherwise good 1992 CAD E-100 (original semi-topic this thread). Any interest in selling one of the mics, or better, just the EM21 capsule?

PMed

 

[Khron]

One more mic using what seems to be the EM21 - Universum Senator.

 

[jamesmafyew]

And since they were asked for, here are some gut pics of the e22S. There seems to be a diode-connected 2SK170 in series with the capsule coupling cap & ferrite, and the 2 cascode FETs are 2SK369s. EDIT: the 170 is not diode connected, it just looks that way because of the glue bead. The 170 is the input FET. One of the 369s is the regulator, the other is the "upper" FET in the cascode.

 

[Gus]

Does the "top" in the 1st and 4th picture 170 lead go to ground?

 

[kingkorg]

And since they were asked for, here are some gut pics of the e22S. There seems to be a diode-connected 2SK170 in series with the capsule coupling cap & ferrite, and the 2 cascode FETs are 2SK369s. I have not traced the circuit, but I do know that it doesn't quite correspond with the published "schematic".

 

[jamesmafyew]

Does the "top" in the 1st and 4th picture 170 lead go to ground?

No, it goes to the adjacent pin of the "upper" 369 (look on the underside picture).

I apologize, I had an earlier and much longer post before those four pictures, addressing several of the questions raised in the thread about this mic. But it seems to have been moderated out of existence. I'll try to summarize it from memory later today when I have some time.

 

[jamesmafyew]

As best I can remember:

I'm actually the one responsible for the gut pic of the E-100 in the OP; it's from my blog.

In any case, I have several e22S and like them very much, but find that they sound pretty different from any other SDC I've used. And they also sound nothing like any other mic that uses an EM21 capsule. While I would guess that Josephson selects/tunes and/or modifies the capsules that go into the e22S, I think the capsule housing is probably the biggest factor in the unique sound.

Like the aforementioned Schoeps V4U, the e22S has a longer path around to the back of the capsule. In my experience (having neither a published polar plot for reference nor the equipment to generate one), the e22S does narrow significantly in the treble and develops a rear lobe in the top two octaves. I remember talking into the back of it inside a super-dead vocal booth one time, and the sound was basically all sibilance, whereas at 90 degrees it was very muffled and dark sounding. On drum shells, the cymbal bleed is decidedly darker than any other condenser I have used. So in general I think that it behaves a little like an LDC at higher frequencies.

As to the question of whether the "tube" housing creates a notch (re: this post), it doesn't that I can hear or measure. There *is* a small dip in response around 4-5kHz, which I first noticed while doing comparisons of reamped distorted guitar tracks. Pointing the e22S at my desktop monitors playing pink noise (1/24 octave resolution, 100x average), that dip is visible but almost insignificant. There's certainly not a huge deep notch. But I do wonder if the small dip around 5kHz is a big part of why I like the mic on guitar cabs as much as I do -- it takes some of the 'harsh' out of the typical peak that most guitar speakers have around 4-5kHz. And if the treble is narrower like an LDC, and then maybe it's receiving treble energy from a relatively smaller portion of the cone, reducing some of the weird high-frequency phasing artifacts that I hear whenever I try a "normal" SDC close up on a cab.

I also did a reamp test of the e22S vs the Equitek E-100, which is posted here. Obviously they are not much alike. Since neither circuit does any EQ that I can see, then if they really use the same capsule, differences must be down to housing, tuning, and/or modification. But again, my bet is on [mostly] the capsule housing -- which is custom machined (in California) and so probably the most expensive component of the mic anyway.

 

[kingkorg]

Thank you so much for this vauable info. The notch due to housing was just my best guess based on many experiments i've performed.

That capsule is absolutely very tricky to compare from piece to piece, just because of the tunable backplate. It is enough to just move the backplate by a couple of degrees and the result is drastically different. So Josephson has definitely a very tunable capsule to work with.

Josephson in their maual also claims the diaphragm is gold sputtered which the Primo isn't. It could easily be a custom capsule they use

 

[k brown]

Yes, it seems that AT's very first cardioid mics (AT 811/813) used a capsule that looked identical to the (long-discontinued) Primo EM68, except for having a gold diaphragm and different FET circuit board on the back.

I also wouldn't be surprised if the Primo capsule in the e22s also used a different, longer lasting and more stable material in place of the foam ring found in the EM21.

 

[jamesmafyew]

I traced it, and it's actually quite similar to the generalized schematic in the manual. What confused me was that the gate and drain of the input FET looked like they were soldered together, but it was actually just a small bead of glue -- no continuity. I don't know the value of the gigohm+ resistors, as they are SMT parts stood on end that look like terminals, and are unlabeled. My meters all max out at 1 Gohm or less, so these are probably 2.2G or more.

BTW that is the correct orientation of the 2SK170; it appears to have its drain and source flipped relative to what you'd expect. Does that actually make a difference here?

I may have XLR pins 2 and 3 reversed here, not sure.

 

[kingkorg]

Interesting thing is that the capsule is externally polarized, even though they are electrets. It could be they wanted to ensure the polarization doesn't "wear out" over time, ot that it's indeed very custom variant of this capsule. It would be nice to test the headroom of the circuit, i guess it should be high due to cascode.

 

[jamesmafyew]

I have had them clip on big drum hits before (I'm talking about a really hard-hitting metal drummer, can't stand to be in the room with him without earplugs), always asymmetrically (positive peaks clipped, negative not). The rated max SPL is 144dB, but it's hard for me to imagine that even this drummer is producing that SPL at 10cm from the drum head. There is a thread on GS where someone complains about the e22S clipping and it turns out to be asymmetric phantom power producing a DC current in the transformer secondary: https://www.gearslutz.com/board/high-end/821703-josephson-e22-owners.html#post13387599

In my case, I was using an Apollo x8 during that recording and I have no idea how precisely matched the phantom resistors are in those interface preamps. I've not gotten clipping from the e22S at other sessions. I normally use them into API 312s where I have hand-matched the phantom power resistors on each channel to within 1 ohm (0.03% tolerance).

One thing I notice is that there is no reservoir capacitor for the FET supply voltage upstream of the regulator. I don't have the equipment available to test, but it seems conceivable for the regulator to drop out if there is a sudden demand for current. I notice that the C715 schematic shows a cap ahead of the regulator, but there is none here.

 

[k brown]

Interesting thing is that the capsule is externally polarized, even though they are electrets. It could be they wanted to ensure the polarization doesn't "wear out" over time, ot that it's indeed very custom variant of this capsule. It would be nice to test the headroom of the circuit, i guess it should be high due to cascode.

That, plus the diaphragm being gold would suggest a custom run for Josephson.

 

[stridentlinear]

One of my friends has this old Teac he's not using, and I thought of this thread. Told him it might have a decent capsule.

It's an ME-50, but looks just like the other models (the 80 and 120), only with an unbalanced trs cable (weird). Anyone know if these are using the same capsules? I googled an old sprec sheet and the frequency response looks real similar. I'm guessing it's probably same thing / cheaper components.

Anyone?

 

[kingkorg]

One of my friends has this old Teac he's not using, and I thought of this thread. Told him it might have a decent capsule.

It's an ME-50, but looks just like the other models (the 80 and 120), only with an unbalanced trs cable (weird). Anyone know if these are using the same capsules? I googled an old sprec sheet and the frequency response looks real similar. I'm guessing it's probably same thing / cheaper components.

Anyone?


View attachment 108516

Seems like it, it doesn't need xlr as it's battery powered. Your friend could easily remove the capsule to check if it's the one.

 

[Wordsushi]

My speculation is that the ME-50 capsule differs from the ME-80/120 capsule. In the 80, you can see a more definitive space between where the capsule ends and the vent lines begin. If the ME-50 capsule is the Primo, it would have to unscrew right above the topmost vent cutout, which would make the head section of the mic less sturdy in construction. I don't think they separate.

 

[stridentlinear]

Good observation. I don't totally hate the frequency response, though. Might still be usable. I'll tell him it's a piece of junk and take it off his hands.

Thanks.