advice for first tube mic clone build

[kip.duff]

Obviously based on my original post, it was/is my intent to build a tube mic.  However, since it seemed similar to what I was thinking of building, since it seemed like an interesting design with the 5654W JAN tube,  since I got the impression that gathering together the right components was going to be daunting for a U47/U67 build, and since the cost seemed not much more than the cost of the components, I ordered an Advanced Audio CM48T outfit for $595.  I have not ruled out building a mic- this just seemed an easier way to get going with a U47 inspired design. 

I hope  you guys will offer your opinions about this mic if you have any- as well as mod opinions if you have any or feel they are necessary.  As with the K2, I'm not committed to this mic- just excited about trying it out.  Since I know (at least in the case of my tube hifi kits) that things like tubes and capacitors need a break in, I am going to set up my recording gear in front of the stereo and run it for some time before I critically use the mic.

As with the K2, I'm very curious to see a schematic- so far found none.  I have seen the schematics of the original U47, but there's  obviously gona be some- or many differences (35V heater from plate circuit?).  I have contacted AA on this- haven't heard back yet.  Any tips appreciated.  Update: I believe I will be getting schematic from AA.

Though maybe not appropriate for a DIY forum, I may post a sample recording.

Thanks, Kip........ 

 

[ln76d]

In the price of CM48T you could make some inspired build with much more proper components than chinese capsule and transformer. Schematic of CM48T was somewhere here. Also it was commented here in some topic.  It has not much to do with the real U47. Sensitivity is also to low. There's no way to get similar sensitivity  from 6ak5 the way as Dave tried to adapt U47 schematic.
There was somwhere link to to rode NTK hand drawn by  GUS. Except extra multipattern connection K2 is practically the same.

 

[kip.duff]

In the price of CM48T you could make some inspired build with much more proper components than chinese capsule and transformer. Schematic of CM48T was somewhere here. Also it was commented here in some topic.  It has not much to do with the real U47. Sensitivity is also to low. There's no way to get similar sensitivity  from 6ak5 the way as Dave tried to adapt U47 schematic.
There was somwhere link to to rode NTK hand drawn by  GUS. Except extra multipattern connection K2 is practically the same.

Thanks for reply.

I already have Gustav's NTK schematic- thanks for tip though.  I have found a prototype schematic of CM48T on Gslutz from 2016- before actual production.  Also have limited  hand drawn schema from AA- final version to come aparently.  Since the CM47T is intended at this point for instrument and guitar amps, my guess is that sensitivity will not be a problem?  However, since the DIY build will have theoretically "better" components, I'm all for that.  But if parts or the design are off, incompatable, or don't have synergy, the result will suck anyway.   

Yes- I still want to do a U47 type build.  I was just impatient to get going with something.  Not having knowledge and parts availability like yourself,  it's difficult to start decent path.  I am in early stages of piecing together a plan.  So far:  *Vintage Microphone D-67 PCB kit by Dan B  *SYT-5 gen 3 mick body kit from Studio 939  *TPS100 PS for C12 kits from Studio 939  *Mouser BOM for upgraded PS  for C12 PS from Group DIY C12 build thread (adjustable voltages I think)  *Mouser BOM for mic from Vintage Microphone D-67 page  *Capsule from Tim Cambel or Maiku (which model?)  *Telefunken EF806S tube  *AMI T67 Tx.  I will consider putting in Russian surplus caps in signal path if they can fit.  What's wrong with this?

 

[iturnknobs]

I love the component vs. sound quality discussion, but I think regardless of components, mic functionality seems to matter most. Through different forks in the road, I ended up building 1@D-EF47(omni/cardioid) with Dany psu, 2 matched@CS-4 type w/AMI 11-pattern psu and 1@D-EF47 pcb+custom back capsule pcb add-on for AMI psu 11 switching pattern... Frankenstein.

The ability to use/exploit both sides of the capsule simultaneously, should be the goal of this project, IMHO. After doing work on 4, I think that the Figure 8 is amazing. Cardioid with the back capsule switched out is noticeably better. Audio "black" is effective to say the least for "3D" perception. Omni seems to be a pattern that most of us cannot "exploit". Church stuff, orchestral decca tree and other eccentric pattern are not always usable for many of us. Figure 8 seem to be "strong" up close on axis. Omni appears to be just as-is/so-so... up too close. Low end is really good on these mics when functioning properly. Body type seems to make a difference... Aputis vs. AMI.

Salt and pepper to taste. Dennis at AMI is really helpful. Dany Bouchard looks like he might have some really great body options available soon.



That's all I got.

 

[iturnknobs]

Another member's comments in a related thread dropping grip resistors from 1G to 100mOhm(approx) seemed to clean things up.
Misha? Misha3?

 

[wlinart]

Yes- I still want to do a U47 type build.  I was just impatient to get going with something.  Not having knowledge and parts availability like yourself,  it's difficult to start decent path.  I am in early stages of piecing together a plan.  So far:  *Vintage Microphone D-67 PCB kit by Dan B  *SYT-5 gen 3 mick body kit from Studio 939  *TPS100 PS for C12 kits from Studio 939  *Mouser BOM for upgraded PS  for C12 PS from Group DIY C12 build thread (adjustable voltages I think)  *Mouser BOM for mic from Vintage Microphone D-67 page  *Capsule from Tim Cambel or Maiku (which model?)  *Telefunken EF806S tube  *AMI T67 Tx.  I will consider putting in Russian surplus caps in signal path if they can fit.  What's wrong with this?

Your plan looks strange to me: you want to build a U47, so you start with a U67 pcb, components and body, and a C12 psu (although you can make it compatible with the u67), with a capsule from Tim Campbell (CK12 type of the C12 or elam251 microphone) or one from Maiku (who has k67, k47 and ck12 type of capsules).

Another option instead of the CM48T is the beesneez Oliver. They have 2 versions, cardiod only and full multipattern. Great price, and probably closer to the real deal in comparison with the advanced audio version.

If you would still like to build the u47, here's what i would do when i will build my u47:
I would build it on acrylic point to point, like this: https://groupdiy.com/index.php?topic=55745.0 The schematic is simple enough, 8 resistors and 3 capacitors. But maybe that's a little bit too much for a first time build. So http://www.vintagemicrophonepcbkit.com/D-47.html or http://www.vintagemicrophonepcbkit.com/D-EF47.html is alo a great choice.
body would be https://store.studio939.com/product/gt-2b-microphone-body or https://store.studio939.com/product/budget-47-body-kit
capsule could be maiku k47, beesneez, thiersch m7, heiserman hk47,...
transformer: haufe BV8 (contact A. Grosser for those), AMI,...
PSU: https://groupdiy.com/index.php?topic=53011.0 the MKPSU
...

 

[ln76d]

Definately 100M fits better this topology than 1G

Except Haufe, there are really good Moby and FAB BV08.

 

[kip.duff]

Thanks for these responses.    Exciting.  I am working 10 hrs today in LA as truck mechanic.  Will take a while to process this info and respond.

 

[wlinart]

Definately 100M fits better this topology than 1G

Except Haufe, there are really good Moby and FAB BV08.

Those i forgot indeed 

 

[kip.duff]

Your plan looks strange to me: you want to build a U47, so you start with a U67 pcb, components and body, and a C12 psu (although you can make it compatible with the u67), with a capsule from Tim Campbell (CK12 type of the C12 or elam251 microphone) or one from Maiku (who has k67, k47 and ck12 type of capsules).

U47 v U67.  My belief when I originally posted at top was that M47 and U67 were similar- U60/67 revised  version of U47 because no more  V14 tube.  I considered the project a "U47/U67" build.  Thought U47 more of a problem because I didn't realize there were quality substitutes for the VF14 metal tube.  Also, the PSU at Club 939  "works for most mic builds other than U47"- so PSU would be easier.  I like the sloped head grill of the U67 also.  BUT, these are the opinions of a novice.  I would really like to know why you lean towards the U47 if that is the case- and you have a moment to elaborate. 

After looking at the U/D67 schematics again, I do prefer the simplicity of the U47.

After some reading, for a U47 build, I'm leaning for the the D-EF47 because looks like more build info.  Haven't found schematic for D-47 yet.  Can't believe the great prices for the NOS Telefunken tubes that I never heard of.

Beesneez Oliver cardioid: $423 US- wow.  Didn't see that- still think I'm gonna do a build.

Thanks wlinart.

 

[kip.duff]

The ability to use/exploit both sides of the capsule simultaneously, should be the goal of this project, IMHO. After doing work on 4, I think that the Figure 8 is amazing. Cardioid with the back capsule switched out is noticeably better. Audio "black" is effective to say the least for "3D" perception. Omni seems to be a pattern that most of us cannot "exploit". Church stuff, orchestral decca tree and other eccentric pattern are not always usable for many of us. Figure 8 seem to be "strong" up close on axis. Omni appears to be just as-is/so-so... up too close. Low end is really good on these mics when functioning properly. Body type seems to make a difference... Aputis vs. AMI.

Salt and pepper to taste. Dennis at AMI is really helpful. Dany Bouchard looks like he might have some really great body options available soon.



That's all I got.

That's a bit . 

*I believe stock  D-EF47 build can only do omni or cardioid.  Your other three builds achieve figure 8- am I right?
*are you saying using front and back capsules in figure 8 can give more space/air/3D than cardioid even when using for a single source- like mic in front of solo instrument amp?
*"Cardioid with the back capsule switched out is noticeably better."  Can you clarify? 

Thanks iturnknobs

 

[wlinart]

U47 v U67.  My belief when I originally posted at top was that M47 and U67 were similar- U60/67 revised  version of U47 because no more  V14 tube.  I considered the project a "U47/U67" build.  Thought U47 more of a problem because I didn't realize there were quality substitutes for the VF14 metal tube.  Also, the PSU at Club 939  "works for most mic builds other than U47"- so PSU would be easier.  I like the sloped head grill of the U67 also.  BUT, these are the opinions of a novice.  I would really like to know why you lean towards the U47 if that is the case- and you have a moment to elaborate. 

Well, I don't actually lean towards the u47, i lean more towards the u67. But since you posted this:

Yes- I still want to do a U47 type build.

I thought i would give you advise on this.

After looking at the U/D67 schematics again, I do prefer the simplicity of the U47.

That is something which i consider important. The U47 is probably easier to build.

 

[ln76d]

Here's rather not only problem with sensitivity.  But the sensitivity is also big part of original U47. There's several reports of different response between U47 and U48 and there's only marginal difference in sensitivity. Many manufacturers just used German/Austrian microphones legacy to sell cheap microphones as something "boutique" (or just call it as you want). There's few much better ways to use 6ak5/5654 tube in microphones circuits, but this way it isn't U47. Also i don't understand some approach in diy builds, which have not much in common with original microphones, but people loves to call it "clone"
There's a huge difference between U67 and U47. U47 except pretty rare topolgy with use of single voltage node for all the circuit sections, working as a radiator for cold nights in the studio, it's pretty simple and really good design with marginal phase flips etc.
Capsule response (i prefer here M7 over K47) is also much different character than K67/K87 etc.
U67 is much more complicated design, you can treat it as pretty big EQ There are feedbacks, phase flips and many other stuff. Both circuits are little bit hard to "cloning" due to multiple reasons. Both also adds something own to the response.

 

[kip.duff]

Capsule response (i prefer here M7 over K47) is also much different character than K67/K87 etc.

Thanks for your response.

"M7 capsule" can have a wide meaning.  If you are referring to something that would work for my build, do you mean Thiersch  STW 7/7.1, PVC?  OK for U47, U67, or both?

 

[kip.duff]

That is something which i consider important. The U47 is probably easier to build.

Yes- easier to build is nice.  Also,  for me, other reasons as well.  Though I have no technical arguments to back this up,  my gut instincts have always been feverishly against what appear to be "excessive" conductor mass and/or length in any audio signal path.  I love the high mechanical quality of the Cardas speaker binding posts.  But I can't bring myselt to use them because there is such a large mass of metal. 

 

[ln76d]

Thanks for your response.

"M7 capsule" can have a wide meaning.  If you are referring to something that would work for my build, do you mean Thiersch  STW 7/7.1, PVC?  OK for U47, U67, or both?

M7 is the capsule model manufactured originally by Neumann Berlin/Gefell. Used in U47, M49, UM57, CMV563 and few others. 
Yes, Thiersch makes best recreation of this capsule with two option of diaphragm material.
It's predecessor of K47/K49 which were used also in U47 and M49 as also U497, U47Fet, M147/M149 and others.
K67/K87 capsules were used in U67, U397, U77, U87, TLM103 and others.
From AKG most known is "brass" CK12 used in C12, C24,  C414E/EB, M250/251, SM203/204 etc.
All of these capsules have different response etc. Most similar to each other is M7 and K47.

 

[mateus]

Heyas! Kind of an old thread but very interesting findings and opinions in here.
I tought I could share my 2 cents of experience with the K2 microphone, but unfortunately not without a big text, so sorry about that.

I'm a blues/rock record producer mainly, I own a K2 for 10+ years now and yeah, it don't get to track as much as I would like when I got it, but there's a little bit more about it. I got it used from a friend for cheap, altough it was a big investment for me anyways.

I always try and encourage people around me they should go for knowing their equipment as best as they can, is all aspects, trying them with everything and everywhere. I know this isn't near as real as one could wish since the relationship time/money in production business is always a huge constrain, but anyways, that's one of my motos.

All and all, I had some success using it for a couple acoustic guitars in a dark sounding medium room, kinda omni pattern, different preamps, mostly Neve AMEK's, Focusrite ISA's and such, most the time at least at 2k+ impendance, had some success at a couple of low-register male vocals, same almost omni pattern, same pres, and quite a good number of success at close mic'ing up bass cabinets, open medium sized room, almost cardioid pattern with either a CAPI VP312 preamp, an Avalon VT737sp preamp or an UA LA-610 preamp, going for a lowered input impedance for this however (~1.2k ohms in VP312, if I remember corretly, 800 ohms in VT737sp, and 500 ohms in LA-610), depending on the the song and artist. In all these occasions I had good musicians and good instruments, good full sounding folk guitars, great sounding basses/amps/cabs and good experienced singers...

BUT

There's one use/function that makes me love my K2, and made me have it as my main go-to mic for that position in every drum recording session, almost every drum kit, almost every song and almost every drummer, outside kick drum mic!
A little story behind that is that I grew up working with "everyone's" go-to, things like NS10 woofers and U47 Fet-ish mics, and for the last 6-7 years I've have been seen a great increase in artists asking/referencing me for more grit, more dirt, more balls in their drums, song after song, specially in rock, stoner, and such, but also in a great deal of blues and even jazzy productions. One day I tried the K2 mic + UA LA-610 combo and never had anything else being able to beat that for that particular mic'ing, any genre, any musician, with very few exceptions. I really do recomend you try it next time you're going to track your next rock drummer, specially if you have been using tons of compression, samples and saturation. I feel it brings out a huge, compressed, larger than life, ballsy, dirty kick bass drum that still sounds natural and tight if you want to. For that I always use it in full cardioid, very close to the head, not the air hole, slightly angled, LA-610 in 500 ohms, pad activated and gain to taste/colour.

For a small example, here's a video from a song I produced/tracked/mixed/mastered, it was tracked live and everything done during a workshop, not much treatment, not much eq, not much compression and no samples at all.



To sum it up, the very best outside kick mic I have ever used for tons of genres!
My 2 cents owning and using a Rode K2, hope it helps!

Cheers!

 

[shimon]

I'm trying to track down anyone that can tell me more about modding an NTK. I've got a good start from moamps here on the forum. I could use a couple more answers. I'm going to be putting in a capsule that has 3 wires, it is the K7 from beeznees. I assume the extra wire is cause its double side mic. I also heard that an ntk with the right capsule upgrade can be retrofitted to work in figure 8. I opened mine up and noticed that pin 7 is unused. but I don't know where and how to route the wire.
lastly even if i can't get the figure 8 functionality, I would like very much to include an input transformer in the mic, i don't know much about these things but i think it has to be around 9:1 and small enough to fit inside the microphone. I saw lundahl has one that might fit. again I know nothing, especially the math behind it all, i'm not tryingto become an electro wizz, just want to record guitar that sounds goood.

 

[pinchemotherloaf]

a) I want to build a tube mic clone

Here is a simple design that's around the 6072a and edge terminated capsule. You can leave the rear polarization part off for simplicity. 120vdc not 20vdc! It's an easy build. I got this from Kevin Ink 20 years ago.