Superlux S502 MK2 test, teardown and improvements

[jp8]

But in another hand I can machine SDC bodies in the most appropriate metal with the good thread for MkII capsules !

Hmm, sounds interesting... What would you charge for two bodies? I'd like to have them in the same matte black finishing as the capsules. Would that be feasible? Or would I have to air brush paint them?

Jan

 

[Emmathom]

Hmm, sounds interesting... What would you charge for two bodies? I'd like to have them in the same matte black finishing as the capsules. Would that be feasible? Or would I have to air brush paint them?

Jan

I must ask "my buddy" who does all my metal gear. Myself, I don't care about cosmetic so a bronze or inox body (for ex.) would suit me. For a black body I must see with him but in any case it's gonna be about painting...

We need non magnetic metal : have you guys some recommandation ?

About the diameter of the body and the step of the threading I must buy a MkII and measure the capsule. About the thickness of the body it depends on the chosen metal's strenght and rigidity (but I'm thinking of 2mm thick)

Now, the circuit... is it still Jan stuff ? could he do on a 19mm width board ? which length knowing that XLR connector will certainly be soldered at it ?

The capsule exists, the electronic board has to be designed (also mechanically) and then we'll know how to manage with the body...

2 other alternatives :
- print a 3D body (my "metal friend" does it also very well)
- cut the capsule holder (of course professionally) and adpat it to a new body > I don't know what is in the thread part : could @MicUlli show us a close pict ? There should be some connector... by keeping the capsule holder one could exchange capsule or body with real Schoeps

 

[Icantthinkofaname]

I must ask "my buddy" who does all my metal gear. Myself, I don't care about cosmetic so a bronze or inox body (for ex.) would suit me. For a black body I must see with him but in any case it's gonna be about painting...

We need non magnetic metal : have you guys some recommandation ?

About the diameter of the body and the step of the threading I must buy a MkII and measure the capsule. About the thickness of the body it depends on the chosen metal's strenght and rigidity (but I'm thinking of 2mm thick)

Now, the circuit... is it still Jan stuff ? could he do on a 19mm width board ? which length knowing that XLR connector will certainly be soldered at it ?

The capsule exists, the electronic board has to be designed (also mechanically) and then we'll know how to manage with the body...

2 other alternatives :
- print a 3D body (my "metal friend" does it also very well)
- cut the capsule holder (of course professionally) and adpat it to a new body > I don't know what is in the thread part : could @MicUlli show us a close pict ? There should be some connector... by keeping the capsule holder one could exchange capsule or body with real Schoeps

I would say brass or aluminium would be best.

 

[k brown]

Sure! There are a number of really usefull mods described in this thread, nicely summarized by @Voyager10.

You specifically mentioned to pair the CM-63 with the 3U capsules, but it yields a slightly different tonality when compared to the CM-60 + 3U combo, which I liked better. It's a bit flatter in the highs. I assume the differences are caused by the different back chamber and slots design. I'd suggest to also consider the Alctron T-02A instead of the CM-63, which I expect to sound identical to the CM-60.

You can hear the tonal differences in @joulupukki 's Blind Test (link below). Though both the CM-60 and CM-63 have slightly different KM84 style circuits, both circuuts are dead-flat in the highs, so I'd reason that tonal differences in the highs should be caused by the capsule/body combination.

Thread 'Four KM-84 Clones - Blind Test' https://groupdiy.com/threads/four-km-84-clones-blind-test.89135/

Having done the KM84 "project", the S502 Mk2 capsule similarities with a Schoeps MK4 triggered me to pick up cloning a CMC6 MK4 as the next project. Just not with a standard Schoeps circuit, but my own.

Jan

What do y'all not like about the stock CM-63 capsule?; I think it sounds quite nice.

I experimented with removing the front grill, and got a very flat response that's useful for close up use.

(Sorry, I meant to ask this earlier in the thread, but got distracted.)

 

[ubxf]

I like the S502 MK2 and if it can be better I'm all for it just trying to bring it back to the original idea

 

[bremusound]

I would say brass or aluminium would be best.

I would say aluminium shouldn‘t be first choice because of the fine threads (pitch is 0.3mm IIRC). Brass would be nice!

 

[Khron]

I would say aluminium shouldn‘t be first choice because of the fine threads (pitch is 0.3mm IIRC). Brass would be nice!

... And because of the potentially-uncertain electrical contact (since it oxidizes instantly, and the oxide layer, while thin, is highly acid-resistant and electrically-insulating).

 

[jp8]

Brass is easier to machine, indeed. Of all the SDC bodies I examjned, the brass versions had the best looking threads.

ARe you sure the thread pitch is 0.3mm? Any reference? I cannot accurately measure the thread pitch with my calipers with worn out pins, but comparing it under a microscope with a Behringer B-5, I'd say they are identical. AFAIK, the B-5 pitch is 0.45mm.

Thread diameter is 19.2mm, whereas the B-5 measures 19.0mm. This is why the B-5 capsule does not screw on the S502 MK2 interface, but that capsule loosly fits on the B-5 body.

I'm afraid we'll have to machine a dedicated body with exactly matching dimensions and threads.

A complicating issue is the diameter of the white capsule interface of 18.8mm, leaving only 1.2mm/2 = 0.6mm wall thickness for the body.

I'm afraid we'll also need a new interface, which has to be 3D printed or machined from PTFE.

Jan

 

[Emmathom]

Hi
according to Jan measurements (he's got a MKII version) a first drawing of the mic body...

- 19,2mm is the largest width so the whole mic outside diameter could be (19,2mm thread + 1mm thickness x 2) = 21,2mm - or 22mm -
- we must go with some brass tube which width should be something about 18mm inside / 22mm outside : 18mm inside to cut out for the interface diameter (18,8mm) and for the thread diameter (19,2mm)
- below the interface collar the tube can be cut (by the XLR side) to get 1mm thick
- the interface can be glued with epoxy...

So the mic body could be machined in one brass tube piece... (I must check that but I'm confident)

 

[janpanis]

Hi All,
The S502 "repair kit" circuit schematic is now finished. Here is the circuit...
If you have a 502 1st version a lot of components become superfluous (the dcdc-converter is not needed)...

Hello Ulli, great design, but I miss the two potentiometers in the Vpol circuit, they are very handy to even out small differences in the sensitivity of the capsules!

 

[MicUlli]

Hello Ulli, great design, but I miss the two potentiometers in the Vpol circuit, they are very handy to even out small differences in the sensitivity of the capsules!

Maybe, but i swear on trimpot free designs
The capsules match very well. Small differences can be handled in the DAW..

 

[MicUlli]

Hi
according to Jan measurements (he's got a MKII version) a first drawing of the mic body...

- 19,2mm is the largest width so the whole mic outside diameter could be (19,2mm thread + 1mm thickness x 2) = 21,2mm - or 22mm -
- we must go with some brass tube which width should be something about 18mm inside / 22mm outside : 18mm inside to cut out for the interface diameter (18,8mm) and for the thread diameter (19,2mm)
- below the interface collar the tube can be cut (by the XLR side) to get 1mm thick
- the interface can be glued with epoxy...

So the mic body could be machined in one brass tube piece... (I must check that but I'm confident)

OOps, that is not correct
The capsules have an inner thread, not an outer one!

 

[Emmathom]

OOps, that is not correct
The capsules have an inner thread, not an outer one!

Ok... I don't own one so I'll check that carefully when I'll receive my mic

 

[Emmathom]

@MicUlli what is the outer diameter of the capsule please ?

 

[pmfalcman]

I would say aluminium shouldn‘t be first choice because of the fine threads (pitch is 0.3mm IIRC). Brass would be nice!

Spot on!
I would even say that aluminium shouldn't be a choice at all.
Regular threads in aluminium tend to jam badly. High friction coefficient. Fine threading would be a nightmare. Most people would probably end with non-removable capsule.
And there's electrocorrosion issue as well, when alu comes in contact with copper, brass, steel etc.

 

[Emmathom]

Spot on!
I would even say that aluminium shouldn't be a choice at all.
Regular threads in aluminium tend to jam badly. High friction coefficient. Fine threading would be a nightmare. Most people would probably end with non-removable capsule.
And there's electrocorrosion issue as well, when alu comes in contact with copper, brass, steel etc.

I think brass is the good choice... (the only thing is that fingers mark brass so you have to regulary "clean" the mic with some cloth, but that's not an issue...)

BTW : I always stock my mics with silica gel bags next to the capsule

 

[Emmathom]

Had my "metal guy" on the phone today and we discussed about the Superschoeps SDC project...

He said that machine a one piece tube of brass will be a bit difficult and expensive (lot of work) but he proposes a brass body and a "adaptative ring" between the capsule and the body which will have the thread for the capsule and the housing for the interface. This ring (~20mm high) is much easy to work with and could be glued (epoxy) on the body.

About metals, he's ok with brass but also proposed adonized aluminium which is more tender to work with...

I'm gonna soon order an MkII since I will need it for adjustments but my priority is to install @MicUlli circuitry and use the mic in ORTF configuration. Since I can't do everything in the same time, the SDC pair comes in a second step for me and I'll have later to buy a second mic.

Do one of you already tried a MkII capsule on a Schoeps pré ? and vice versa ? what's the audio and measurements differences ? (if there are significant ones)

Here picts of S502 capsule 1rst version and Oktava thread (which don't fit together unfortunatelly). The S502 1rst interface has its needle mounted on a spring so the capsule pressures the needle. I've been told by Jan that the MkII hasn't got that spring and it's a hard contact.

 

[pmfalcman]

I think brass is the good choice... (the only thing is that fingers mark brass so you have to regulary "clean" the mic with some cloth, but that's not an issue...)

Finger prints - true, but only on a new body or a regularly cleaned one
After a while the brass gets a nice patina and finger prints are a non-issue. Brass ages beautifully.
If you want a shiny brass all the time you can cover it with lacquer. Or paint it. Colour match to the capsule.

 

[pmfalcman]

Anodized layer is non-conductive.

@Khron already warned about potential electrical conductivity problems with raw aluminium.

Anodized is out of question entirely.

As for the coupling ring, I was already thinking that this would be a best solution.
I wouldn't fix it with expoxy though. Conductivity again
Either make it a touch oversized on one end and screw in the body while frozen or just use a tiny dab of a thread locking compound - Loctite or similar.

 

[Emmathom]

Anodized layer is non-conductive.

@Khron already warned about potential electrical conductivity problems with raw aluminium.

Anodized is out of question entirely.

You mean adonized alu is out of question ? why if it's not conductive and "inert" because of adonization ?