Soliloqueen's k87(k67) and k47 capsules

[soliloqueen]

One interesting thing I just saw on my photos, is the presence of what appears to be 8 small beads of something or other arranged symmetrically on the membranes, close to halfway between the rim an center..

Are these the spacers that were mentioned, in order to avoid clinging to the backplate in dry atmosphere?

If they are on the membrane itself, would they not add mass?

yes, those are little dots of dried plastic/glue they added to try and physically hold the diaphragm up in dry climates. it didn't work. they are attached to the backplate and are about half or 3 quarters the depth of the capacitance, about 30 micron tall. i'm not clear on how they accomplished this. my instinct says that they put the dots of glue on the plate, then put a 30 micron shim on, put on some tensioned palstic wrap, let it dry, peeled the plastic wrap, put on the correct shim and then installed the real diaphragm. that's what would make the most sense given the material and shape of the dots, but i cannot verify this as factually accurate.

 

[soliloqueen]

Do you mean this? I’ve seen it in one U67. I should have written down the serial number.

first time seeing a u67 one. i believe i've seen this in a u60, but never in a production 67, but it was some time ago and i may be mistaken. Very interesting! Yes, that's the wire mount. I removed this from my capsule primarily because when I made the first test units with the wire mount, false setting of the screw happened too often. that is to say, it was difficult to tell whether the mounting screw was engaged with the hole or just wedging into the wire mount. I figured this too needlessly complicated for DIYers (and, honestly, most people) so I removed the hassle.

edit:
it also interfered with the chamfer later added to the rear of the plate, which i believe (without proof) is there to make it harder to short the plates in the k87. the plastic shim between the plates is wider than the minimum diameter of the chamfer (it sticks out) which makes it harder for debris to get stuck and also ensures that no matter the production-day tolerance, the critical diameter of the plate never exceeds the spacer. i think this might be why neumann removed it.

 

[soliloqueen]

i noticed something else. i, irresponsibly, have a lot of plates just kind of sitting on my desk or shelf that have begun to patina. the first in-house k87 test plates (top right) have begun to show the barest signs of a traditional green alpha brass patina. one of the plates from the mass production factory (bottom left) hasn't though. it's got a dusty powder-white oxide layer that is starting to speckle and cloud the reflections like you might see on aluminum:


i see this on beta brasses and some bronzes sometimes, from the high zinc or tin content. not for nothing, but it is also obvious from the luster of both plates that they are not the same material at all. this does not show up easily in photos, but they are very clearly not the same metal in person, even underneath their respective oxides.

I also have a k103 plate from an ebay storage unit that was left out a bit, it has a much more intense traditional alpha brass patina:


it is also, again difficult to show in the picture, very obvious in person that the neumann plate and mine are the same or at least broadly similar alloys of brass, even under their patinas. given that i specified 360 brass for the plates, and i know for a fact that the test plates are 360, and they match the neumann plate, i am guessing the mass production factory lied about the brass used to save money. will this affect the performance or reliability of capsules made with leftover mass produced plates during the transition to our new shop? not really, no. but it goes to show that the old supplier isn't trustworthy.

 

[ccaudle]

guessing the mass production factory lied about the brass used to save money

Is there any way to verify that other than something like mass spectrometry? Google AI says X-ray fluorescence is the go-to method, but I don't know how much I trust the answers yet.

 

[soliloqueen]

We are about ready to move the production to our shop. We're just doing some quick bug hunting in the G-Code. There were a couple bugs that were causing things like inconsistent chamfering amounts between holes and other small stuff like that. That and the toolpaths weren't fully optimized yet. All good now. I think we're ready to start our first production sized batch. finally, which is good because it's been uh




interesting

 

[Khron]

I think we're ready to start our first production sized batch. finally, which is good because it's been uh

That doesn't say much, Fusion increments that every time you hit "Save", so...

I've yet to reach 400+ on any of my boards, but i've easily sailed past 100 with some designs at work, so... No big deal

 

[tomas.borgstrom]

I would appreciate that, thanks from me as well!

Would it be possible to also record male voice? I'd like to hear the response to sibilants as well as the overall vocal timbre.

Here's some acoustic guitar. I've attached a picture of the setup. The guitar is upright on a stand to ensure the same distance. I have to sit on my knees and play in a weird position and I'm not a guitar virtuoso to begin with. The microphone is my own U47 circuit with EF12, cardiod through the old 2U Focusrite ISA. The microphone is intentionally quite close looking straight towards the sound hole.

In this test I was quite gentle with the microphone since I usually play strong intense chords. The slight proximity and a lot of direct sound is not easy for a microphone to handle. This way I instantly hear the whole spectrum, the ability for the microphone to separate the tones, reveal harshness and buildup in the low end or a collapse of the soundstage.

I included a Neumann Berlin M7 reskinned by Drefahl. They all sound very close (and very good!). K47V is smoother than the Sennheiser K47 I have and therefore closer to the M7 in sound.

I don't have any singer around at the moment and I won't publish my own voice, even though I'm ok at faking a crooner (a bit out of key) and quite good at imitating David Byrne (fits better out of key). I find it a bit hard to evaluate microphones with voice. You can hear which sounds best on that particular voice but it doesn't say much on a general level. In this setup I think it would be hard to hear major differences with a male voice but I understand you concern with sibilants. If you are worried about that K47 flat is the best choice, especially with a U47. I'm not so fond of K47 equipped U47s. Too much upper mids and therefore often sibilant.

 

[tomas.borgstrom]

As usual the attached sound files does not seem to work. Here's a link to download the files:

https://we.tl/t-z1SJxoYnti

 

[Barry Hufker]

Thank you for the files. That comparison was enjoyable. I thought all three sounds were quite good. My favorite was the M7, but I just enjoy that sound in general.

 

[tomas.borgstrom]

Thank you for the files. That comparison was enjoyable. I thought all three sounds were quite good. My favorite was the M7, but I just enjoy that sound in general.

To be fair to Arienne Audio this is the best M7 I've heard. They vary a bit and I have not heard any clone that sound like Neumann Berlin.

I like them all but the K47F is a bit special, solid and dryer than the other two. Very versatile. I've built some M49 clones with it to some local studio owners. They seem to use them very much on almost everything.

 

[soliloqueen]

i asked one of my staff why the big factory used a higher zinc alloy and he suggested that it wasn't to cut costs, but to allow the alloy to be effectively chromate coated and be able to survive longer periods in storage in the seaside climate in ningbo without needing to be immediately assembled. interesting idea, and not a bad one at all... I am considering the implications of this idea. i feel bad for immediately pointing the finger at cost-cutting. I need to keep in mind that even though they're a huge overseas factory, they've also been making this product for 20 years longer than me. upon closer inspection, there is a rainbow pattern on the mass produced plate in certain lights. it is indeed chromate coated. so they altered the alloy so that there was enough zinc to chromate coat the plate?

(really glad i am able to work with such experienced people in this operation, frankly. i would never have thought of this)