Soliloqueen's k87(k67) and k47 capsules

[tomas.borgstrom]

Well, compared to ribbons, which were the main vocal mics at the time, they were quite sibilant.

Microtech Geffel, who sells mics (or used to) with M7 capsules in PVC, used to say that those mics fall out of spec. and the capsule needs replacement after a while.

Indeed, some people like the lack of bass that is associated with old membranes, for close-up vocals, though.

Just so you don’t get me wrong. I don’t like those capsules at all. I send them for reskin. As I said. I’ve heard two with maintained low end. I’ve also seen and heard twenty year old dried Gefell M7 that sounded very brittle. An expensive product that deteriorates so fast is not acceptable.

I think the PVC debate is an obsession. I don’t work with membranes myself but those who do say it’s a terrible material for that application. Neumann gave up in the 50’s.

I’m sure Arienne can give us a much longer explanation on this topic.

 

[Moby]

Mylar. Drefahl does not do PVC. I've heard a few M7 with the original membrane in good shape. To my ears the M7 reskinned by Drefahl sound the same. Thiersch blue line (PVC) does not sound like Neumann Berlin M7 at all.

Thumb up for the Peter Drefahl work. My experience with his reskins is the same.

 

[Recording Engineer]

So for some of you, Drefahl skinned 3U M7 is where it’s at? If so, got 3U… Mailing is not a problem.

 

[soliloqueen]

So for some of you, Drefahl skinned 3U M7 is where it’s at? If so, got 3U… Mailing is not a problem.

It seems this is difficult though as the capacitance gap is wrong? So it's a high effort reskin for him

 

[Recording Engineer]

It seems this is difficult though as the capacitance gap is wrong? So it's a high effort reskin for him

Hadn’t heard that yet, but I wouldn’t be surprised! I’ve had this 3U for a few years now… Still haven’t tried it in anything yet! But same as your V1 Flat K47 pair of your’s I still have! I did finally put that pair of your V1 K67/87 in 67 types with Moby transformers and Mullard 10Ms from Christian. Definitely brighter/extended as you had mentioned they’d be. I still haven’t used them much, but honestly, they’ve already grown on me! It makes you realize how rolled-off on the top the original actually is!

 

[thomasdf]

I am doing a lot of A/B tests in a beautiful 47 build, and so far my favorite is a 3U m7 capsule, but to my ears it sounds a liiiittle too flat and lacks a tiny bit of oomph in the low mids to get that smoky / golden era tone. On top of that it sounds great up close, but lacks a bit of that *zing* when backup up from the capsule to a more usual / standard distance.

Would your vintage k47 be a better candidate for oomph and response coherence ?
Any plans of working on m7s or are you def not working with glue and membranes ?

 

[MaxxDM]

M7's were designed with PVC in mind. Originally, I think they used a membrane of some kind of pine resin or something like that. PVC is elastic in all directions, so it adapts to the capsule, so to speak. On the other hand mylar is quite stiff and does not stretch as much.

As you can imagine, because of the glue process, an elastic membrane is more forgiving than one that is stiff. With the mounting ring, you make the job a lot easier when using Mylar, I think.

Also M7's presence peak (not the 10Khz) was more pronounced on early M7's. Perhaps the more rubbery-sounding PVC (when new), had a sound that was a bit deeper and 'vocal' than with the mylar membrane. I certainly noticed that switching from Mylar to PVC made the capsule more dynamic-sounding in the low mids. Maybe because of the 'stretch' of PVC, I am just guessing here.

I do remember not liking it at first, because things like pick attack sounded a bit dull by comparison. This became a non issue after a year or so, although I always went for the 67 capsule for acoustic, for some reason.

Seems PVC M7 membranes also had a different thickness, and I imagine that the equivalent thickness in Mylar would not work in the exact same way.

The M7 interested me because of the Beatles connection, however, now knowing more about the aging of pvc capsules, I suspect that those u47's had K47's in them by the early 60's. Just guessing.. Sgt Peppers does sound more like K47 were used, to me..

Personally, all things considered, I would rather stick with a good K47 or K67 for the Neumann sound.

 

[tomas.borgstrom]

The M7 interested me because of the Beatles connection, however, now knowing more about the aging of pvc capsules, I suspect that those u47's had K47's in them by the early 60's. Just guessing.. Sgt Peppers does sound more like K47 were used, to me..

It was perhaps a mix. The U48 probably had K47 and the U47 and the U47 converted to U48 probably had M7. The Beatles mixes are processed quite hard so a lot of other stuff influence the sound. There's a demo of Paul singing Here There and Everywhere with a guitar. It sounds quite naked and very nice.

 

[MaxxDM]

It was perhaps a mix. The U48 probably had K47 and the U47 and the U47 converted to U48 probably had M7. The Beatles mixes are processed quite hard so a lot of other stuff influence the sound. There's a demo of Paul singing Here There and Everywhere with a guitar. It sounds quite naked and very nice.

Knowing how stringent the demands of EMI's technical department were, I suspect that they probably substituted the capsules as soon as they went out of spec. which in my experience is a few years, but it appears that none of this was documented (so far), so your guess is as good as mine!

 

[soliloqueen]

we're doing final bug hunting in the g code for all the parts. we've already found and fixed most of the bugs in the backplates, but check out this funny bug in the validation samples for the M7 mount. I'm using fusion 360, so instead of doing nurbs modeling like a sane person would in solidworks or something, i just used a ****-off huge fillet command:


That means that there is a line boundary in this curve where there shouldn't be a line boundary. A human would look at this and realize that it's from using a fillet command and understand that this is supposed to be an uninterrupted surface, but CAM software does not understand the concept of shape. It is programmed to generate toolpaths that ensure that each face fits the drawing within a certain percentage error. It looks at this and goes "oh, two faces!" and generates ideal toolpaths for each face. But it doesn't consider the area in between the faces, and it cannot create an infinitely small boundary between the faces, so the result is:


sorry for the dust i'm handling them with my fingers in my home office which i know I shouldn't do.

the CAM can't generate correct toolpaths for the shape, even though it can do the faces fine, so this will need to be manually altered.

I'm not going to go out of my way to hand-polish the mass production m7 mounts or anything, so I wanted to figure out how good we could get a purely machine finish on these parts. The results are not too shabby:



considering that this is not one material, but brass that we nickel plated after without re-processing, this is pretty good for a machine only finish. this should be nice and cheap for us to do at volume and, most importantly for a small 5ish-person shop, almost zero human effort-time

 

[ubxf]

can I buy a couple of prototypes, it could be earlier ones not as pretty as these

 

[soliloqueen]

can I buy a couple of prototypes, it could be earlier ones not as pretty as these

I'm still deciding on a tuning. I'm also deciding whether to use mylar and alter the backplate to approximate a PVC response or use a novel film. I do have five or so that should be tuned neutral as a baseline. The glue is drying so I'll have more information later. I wouldn't mind parting with one but the full units were a bit expensive to make being validation models.

 

[ubxf]

cool thanks that would be great

 

[soliloqueen]

cool thanks that would be great

i can send you one when they get in and you can pay once you approve the sound

 

[ubxf]

I totally trust you, I'm sure it's going to be great

 

[soliloqueen]

I totally trust you, I'm sure it's going to be great

I appreciate that, but my tastes don't necessarily align with other people's. I'm very sensitive at 5K and much prefer smaller or no boost there, which is not true of most people. Single backplate capsules are contentious in their tuning though. One man's flat might be another man's lacking Mojo and one man's Mojo might be another man's old timey telephone effect. I'll be thrilled if you like it, but if you want you can give me notes on how you want the capsule to sound relative to the Prototype and then send it back and I can design you one that sounds that way and throw it in with the mass production. I can make an M7 or k47 sound just about however anyone wants. Actually, the bad tolerances from the factory were kind of nice because I could separate them by tuning and send different customers with different preferences different tunings. Now that we're doing this in-house and our machining is so much better, I have to pick one. That has been a gargantuan task. Everyone i ask has vastly different opinions on what the k47v should sound like, some of them divergent enough from my opinion that it sounds like a legitimate special effect mic. Can't please everyone though, so I'm just going to go with what I think sounds good.

 

[Barry Hufker]

You've hit it exactly. You can't please everyone, so please yourself and if enough people like it then you've got a hit. But making something unique for everyone can only bite you in the end.

 

[thomasdf]

i am amazed ! Bravo

 

[MaxxDM]

I'm still deciding on a tuning. I'm also deciding whether to use mylar and alter the backplate to approximate a PVC response or use a novel film. I do have five or so that should be tuned neutral as a baseline. The glue is drying so I'll have more information later. I wouldn't mind parting with one but the full units were a bit expensive to make being validation models.

Using a modern plastic film, which is as 'stretchy' as PVC sounds promising!

 

[ubxf]

I appreciate that, but my tastes don't necessarily align with other people's. I'm very sensitive at 5K and much prefer smaller or no boost there, which is not true of most people. Single backplate capsules are contentious in their tuning though. One man's flat might be another man's lacking Mojo and one man's Mojo might be another man's old timey telephone effect. I'll be thrilled if you like it, but if you want you can give me notes on how you want the capsule to sound relative to the Prototype and then send it back and I can design you one that sounds that way and throw it in with the mass production. I can make an M7 or k47 sound just about however anyone wants. Actually, the bad tolerances from the factory were kind of nice because I could separate them by tuning and send different customers with different preferences different tunings. Now that we're doing this in-house and our machining is so much better, I have to pick one. That has been a gargantuan task. Everyone i ask has vastly different opinions on what the k47v should sound like, some of them divergent enough from my opinion that it sounds like a legitimate special effect mic. Can't please everyone though, so I'm just going to go with what I think sounds good.

I'm also liking flater , I'll be happy to give some feedback but won't send it back. When I go to a nice restaurant the last thing on my mind is to give the chef some notes