Superlux S502 MK2 test, teardown and improvements

[k brown]

I don't understand your reference to my "taste for hyper ORTF".

Not only have I never expressed such, but there is no such thing. ORTF, as defined by the people that coined the term, specifies cardiods.

My mention of hypers was regarding the Faulkner phased array of two pairs on the same bar -a pair of omnis and a pair of directionals. The directional pair is not ORTF; it's spaced wider than that. Faulkner most often uses subcardioids at about 18.5"; both pairs are aimed 90 degrees - so nothing at all like ORTF.

If one uses directional mics with a tighter pattern than subcardioid, the spacing is reduced to compensate, so that the two pairs produce approximately the same stereo width (didn't I already explain this?). I like to use the Okatave hypers which are their own unique pattern, so I use a spacing more like one would use for supercardiod (12.5").

 

[Emmathom]

Roger @k brown a misunderstanding on my part...

 

[j.colt]

Thank you for this first adventure with SMD… if it works then anybody can do it…

Edit: It works great!! Very nice sounding mic.

 

[rvperez]

looks great

 

[olafmatt]

As a follow-up to my post #243 in this thread: Got the second S502mkII that I ordered. Out of the box the screws near the capsules were all loose, a true DIY mic! Internals still look like my first one.

This time I took more time trying to figure out how to mount JFET, ferrite bead and 1Gig resistor behind the capsule. It does fit, but only barely so. The hole for the cables needs to be enlarged slightly (from 2.0mm to 2.5mm to fit 4 of the wires I had at hand). With a turning lathe one could remove some of the brass (on the capsule side) leading to that hole to make a little more space.

The photos show basically the stock mic with only the mentioned components replaced by last-millenium through-hole stuff mounted behind the capsule.

 

[MicUlli]

Hi folks,

right now i have shipped the last 2 of 32 repair kits for S502 1st version and S502MKII
If someone wants to order new kits a little bit patience is required. I will start a new batch when the demand is >10...

Best regards MicUlli

 

[Recording Engineer]

If someone wants to order new kits a little bit patience is required. I will start a new batch when the demand is >10...

Best regards MicUlli

I gotta get a UK someone to order one for me when available again then.

 

[rvperez]

me too

 

[Emmathom]

Ulli's PCBA installed in my S502 v1. It works fine. Now I've got to use it in real recording conditions to issue an opinion. What I ear after a quick voiceover test is : very flat FR and silent.

These Superlux S502 capsules (v1 & MkII) are really excellent ! Both of them.

We are developing, @jp8 and I, a SDC mic based on a Schoeps-like circuitry + MkII capsule in a Samson C02 donor body. Some mechanical issues to match the two parts because the Superlux head system is a bit weird (capsule + interface) but we've got a "metal wizard" up our sleeve

@jp8 can say more about his work on diygroup if he wants to since he's the father of the circuitry...

 

[j.colt]

It is indeed remarkably quiet

 

[jp8]

@jp8 can say more about his work on diygroup if he wants to since he's the father of the circuitry...

Well, actually, the only Schoeps-like thing about the circuit are the output stages, but with CFP instead of single PNP for lower THD and improved CMRR. Transistors are factory matched pairs, so no hand-picked Hfe and Vbe selected BJTs required.

The impedance converter is nothing like Schoeps: it's a discrete self-biasing charge amplifier. So no bias trimming and JFET selection required. Unlike the KM84, it has high open loop gain and hence, very low distortion. It's an order of magnitude lower than Schoeps at the same signal level.

The capsule bias generator is also different from the Schoeps circuit. Instead of the unreliable Hartley oscillator, I chose a two-gates CMOS oscillator, similar as in my KM84++, but then supplying a negative voltage of -48V to the capsule membrane. The backlplate is directly coupled to the JFET and applies +12V bias to the backplate.

Maximum output level exceeds 5V RMS into a 3kOhm load. The feedback capacitor of the charge amp was chosen such that a decent sensitivity of 14.4mV @ 94dB SPL was obtained. This results in a max SPL of 145 dB. No pad switch needed...

I'm anxious to learn how emmathom will find them in real use! I won't use them myself, but hope my son, for whom I build all the microphones, will appreciate them.

 

[bremusound]

I’m definitively interested!