Superlux S502 MK2 test, teardown and improvements

[micro1_de]

So that recording used the Superlux microphone body, but with real Schoeps capsules?

Yes.

 

[Barry Hufker]

I agree the Schoeps 934C is a great capsule. The M221B is a fine microphone, but beware as there are fake M221Bs out there. They are sometimes called "Hungarian Schoeps," but there is no such (official) thing. They are Schoeps capsules with copycat bodies and electronics. How good they are depends...

 

[olafmatt]

Did anybody notice that the original circuit in the S502mk2 deviates from the Schoeps circuit and uses what looks like a 5.6V zener diode for D3? My mic has about 5.9V across that diode. They presumably did that because they thought then they can get away with those 6V rated tantalum caps for C5.

Looking at the pics of the internals posted on the first page of this thread again, I also noticed that those pics show surface mount caps for C9 (looks like ceramic even?) whereas my one has through-hole (electrolytic) caps with the legs bent into place.

I ordered a second mic and will try to mount the JEFT directly behind the capsule once it arrives. Don't want to ruin the mic I already have since I'm not sure whether my stock of 2SK117 is genuine or ends up being a noise generator.

EDIT: Curiosity got hold of me and I tried to fit a through-hole JFET plus 1G resistor behind the capsule of the mic I already have. Maybe 15 years ago with better eye-sight and more steady hands I could have done that without any wiring touching the metal case.
Went instead with putting them in place of the existing components with all high-impedance wiring in mid air. Even that was quite tricky to do without anything touching the mice case or the ferrite bead touching other wires than just the gate of the JFET.
Now waiting for the epoxy that holds the bead on the wire to cure, but a first test without that glue showed very similar noise floor to the stock JFET. Hopefully at least better moisture resistance after the mod.

 

[Emmathom]

I agree the Schoeps 934C is a great capsule. The M221B is a fine microphone, but beware as there are fake M221Bs out there. They are sometimes called "Hungarian Schoeps," but there is no such (official) thing. They are Schoeps capsules with copycat bodies and electronics. How good they are depends...

What about the CM 30 F pre I posted ? Does anybody know about it ?

 

[Barry Hufker]

A translation from the Schoeps site: “The microphones of this second generation of transistors offered six capsule types (MKT 2, 4, 40, 41, 5 and 6) and were available for 12-volt phantom power (CMT 30), 12-volt parallel-fed (CMT 40), and 48-volt phantom (CMT 50). The 12-volt CMT microphones were replaced by the Colette series in 1974, but because of their extremely low power consumption, the CMT 50 series continued to be offered until 1982.”
https://schoeps.de/ueber-uns/produktgeschichte/detail/1966-cmt-304050-series.html

I'm guessing the “F” is for French and has the Sogie connector, which I believe was a French standard.

 

[Emmathom]

I don't know if I should open a new thread just for this but I would like to ask the diygroup community about an alternative to AKG C414. Does anyone here own a Warm Audio WA14 or a Lewitt 441 Flex ? How do they sound compared to the original AKG C414 ? Are they close, very different... ?

Sorry to be out of topic > I will open a dedicated thread if it worth the case...

Regards

 

[ubxf]

Since we go far and wide from the original idea, what about using 2 S502 MK2 to make an Ambisonic mic ?

 

[MicUlli]

Here is my mic setup for the next concert in a church:
2 Omnis Primo EM23 spaced 80cm for AB,
Superlux S502 MKII for ORTF,
2 cardioids (MBHO KA200 custom specific) spaced 25cm 90° angle according to Sengpiel,
MBHO KA10 Omni for LF mix to ORTF and Sengpiel pair.
I am very curious how it works out...

 

[Emmathom]

Hi @MicUlli do you plan to get much difference between the 110° of the S502 and the 90° of the MBHO pair ? Speaking in terms of coverage (not sound of course since they are different mics).

80cm AB isn't it (too) much to spaced for AB ? (I know I did 2m at my last recording but it was such a mistake !)
On the other hand you have an omni in the center so the three omnis mixed together should do well...

Let us know please and post a sound sample when mix is done !
Regards

 

[k brown]

Hi @MicUlli do you plan to get much difference between the 110° of the S502 and the 90° of the MBHO pair ? Speaking in terms of coverage (not sound of course since they are different mics).

80cm AB isn't it (too) much to spaced for AB ? (I know I did 2m at my last recording but it was such a mistake !)
On the other hand you have an omni in the center so the three omnis mixed together should do well...

Let us know please and post a sound sample when mix is done !
Regards

Indeed - anything much beyond two feet is where a clear hole in the middle becomes apparent.

 

[MicUlli]

Hi All,
thanks for your hints
I will follow the advice and set the AB distance to 60 cm...
BR MicUlli

 

[Emmathom]

Hi All,
thanks for your hints
I will follow the advice and set the AB distance to 60 cm...
BR MicUlli

60cm or 80cm does not play much until you get "something" in the center (so do you with S502 MkII and MBHO KA10)
I think with these center mics you could even space the AB omnis more... depends on the acoustic, the distance to musicians, et...
We long to ear an excerpt of you recording
Regards

 

[ubxf]

Here is my mic setup for the next concert in a church:
2 Omnis Primo EM23 spaced 80cm for AB,
Superlux S502 MKII for ORTF,
2 cardioids (MBHO KA200 custom specific) spaced 25cm 90° angle according to Sengpiel,
MBHO KA10 Omni for LF mix to ORTF and Sengpiel pair.
I am very curious how it works out...

Is that with your modified S502 MKII ?

 

[Emmathom]

Is that with your modified S502 MKII ?

Yeah @MicUlli did you received your PCB's ?

 

[MicUlli]

Yeah @MicUlli did you received your PCB's ?

Yes i did. As expected some changes were necessary. I was not aware of the core losses of the oscillator inductance. But no Problem, it could be solved by altering some resistor values.
The circuit now performs incredibly well. Self noise is around 14..15 dB SPL, detaillied measurements follow soon. No hf noise components found.
Dirk inspired me to get a S502 1st Version for small money so i can test also in this configuration.
Stay tuned, i think this weekend the design can be released

 

[k brown]

60cm or 80cm does not play much until you get "something" in the center (so do you with S502 MkII and MBHO KA10)
I think with these center mics you could even space the AB omnis more... depends on the acoustic, the distance to musicians, et...
We long to ear an excerpt of you recording
Regards

Any weakness of the center with 60-80cm AB is remedied perfectly by a small amount of panning-in to taste. The amount is small enough to not produce any audible combing.

No need for the complication of a third mic.

Lately I've been greatly enjoying 3' AB with panning-in (to about 81% for my taste).

Some of the later Decca engineers preferred 3' AB (always with outriggers) to the usual 3-mic triangle. With that rig, they panned-in the AB a full 50%, and the outriggers were at nearly the same level as the main AB. Without the outriggers, 3' AB panned-in that much would sound very narrow.

 

[ricardo]

Most good SDC cards are only down about 3dB at 50Hz; easily EQ'd.

I know of only 2 SDC cardioids which are -3dB @ 50Hz in free field and one of them is mine from circa 1980. ALL other SDC cardioids have worse LF.

eg Schoeps MK4's free field is above 100Hz.

 

[k brown]

MK4 (Schoeps doen't specify if it's free field or diffuse field), and Neumann KM 84:

 

[k brown]

As you can see in this graph from Schoeps, there isn't significant difference between free field and diffuse field responses in the bottom octaves.

_______

Most find that when recording in the diffuse field with ORTF (or NOS, DIN, etc.) low EQ is rarely needed.

 

[ccaudle]

MK4 (Schoeps doen't specify if it's free field or diffuse field),

Also does not specify distance, which can make a significant difference with directional microphones. Especially that second graph of the V4U, it is specifically called a "vocal microphone," which could imply relatively short distance FR measurement.