Townsend Labs Sphere Hacking

[mks]

Thanks kingkorg. Makes total sense that assembling omni from two capsules would be a totally different thing. I guess my mission would be to try and find a filter circuit that gets as close as possible. Then filter further before the plugin (or not at all). For two reasons: I'd like to be able to use the mic without being in it's naturally overly bright state...that and I'd have to essentially go right into the plugin when running it on UA hardware (to take advantage of the low latency monitoring I've become accustomed to).

 

[benqbasic]

Hope these pictures help. They are from their fb page btw.

https://imgur.com/HzvtKrh

and

https://imgur.com/85IGoKY

and 767

https://imgur.com/2SSqWAY

 

[dab0815]

sorry if i sound stupid. but afaik the behringer b2 pro also features a 797 k67 capsule. and it got a dual membran design. couldnt that be easily modded to become dual output and match the sphere mic? or am i completely off here?

EDIT: ok ive seen now that you need two sperate PCBs (one for each  output) for the dual output concept to work and the behringer b2 pro needs already both pcb spaces for a single output to work.
so i think you need to swap the two pcbs against two sperate output pcbs for the concept to work. right?

 

[kingkorg]

I have modded a B2 for this purpose. I used two identical pcb's from two different B2s, but i got rid of DC-DC converter on one side.  A sacrifice i had to make. However i did get more headroom, but slightly more noise because of lower polarisation voltage. I use that mic as drum room, guitar cab, vocal mic on loud sources. So the noise isn't an issue.  A lot of mics don't have an DC-DC converter and work just fine.

 

[dab0815]

so you ditched one of the pcbs that include the dc dc converter from each mic and just used the others right?
did you do any mods to the b2 pro pcbs?

which of your mics is more usable as a sphere clone?

id like to build me a sphere clone for vocal recordings but i never build a diy mic before. i can soldier a lil bit and i am confident i  could make one myself but i think i would need a step by step build documentation or something..

 

[kingkorg]

I wouldn't recommend B2 then. You would have to provide source of polarisation, and mod the black box under the head of the mic, wire the pins differently.

I can't provide you with exact instructions. But simplest way i did that is with two PCB's of MXL601 type. You can use the PCB's from Takstar CM60. They are dirt cheap, have schoeps circuits with the converters on each. And you are left with two capsules you can use or sell. Place them in any mic body they can fit. Connect grounds from both and ground backplate of the capsule.

Use 5 pin XLR  for connection, with breakout cable to two regular XLRs. Or if you don't care for aesthetics, just use two cables soldered to PCBs and two XLRs on the other side.

The best variant i've made is very custom. It has variable polarization voltage up to 120v. And custom, very large headbasket for minimal reflections within, and damping under the capsule. Schoeps circuit biased for minimum THD, with some common tuning stuff found on this forum.

I have also done fine tuning of IR(corrective EQ) for every capsule and best results. At this point i believe my emulations are actually closer than the original.

However if any of this is super audible i am not sure, all of this is precision measured, but in the end simplest method i used in the beginning is probably just as good.  Later work might be an overkill.

 

[wstratton]

Has anyone tried using the MicrophoneParts multitrack circuit kit with the Sphere plugin (or contemplated using it)? I’m wondering if the corrective eq built into this circuit, paired with the 797 k67, could achieve similar results, but I haven’t looked too deeply into it. It’s sold out at the moment, but I’m considering giving it a try when it’s back in stock. https://microphone-parts.com/collections/mod-kits/products/multitrack-microphone-circuit-kit

 

[kingkorg]

It is difficult to know not knowing what RP circuit is like. But i see no reason why it wouldn't work with Sphere in general. How accurate emulations will be is questionable, but with some tweaking, measuring, comparing to real Sphere mic i am sure one can get good results.

 

[dab0815]

Im still thinking about building this one

I found some pcbs i would like to use instead of the isk cm60 mic unless you tell me its stupid hehe.

The curcuit boards i consider are these


1 https://www.aliexpress.com/item/1005001830617884.html
this should be higher quality then the ISK / MXL ones right? it also has shoeps circuit. about same price as isk cm60 mic.
version 1 or version 3?

2 https://de.aliexpress.com/item/1005001326599115.html
build after nt1 rode circuit i think. low noise. a bit more expensive than isk cm60

3 https://www.aliexpress.com/item/4001111038259.html
dirt cheap but i dont know what circuit and if it will work

all these should fit in this body.
https://www.aliexpress.com/item/33007361884.html

it says circuit boards fit up to 72mm so the two 54mm shoeps boards wouldnt fit on top of each side by description but in 2 you see the mic body with a 52mm circuit board and it seems that two can fit on top.

if not im considering this large body

https://www.aliexpress.com/item/1005001874660413.html

also as a capsule i will either use a used b2 pro when i find one or im thinking about this capsule:

https://www.aliexpress.com/item/4000401604889.html

one of the reviewrs stated that this was the only capsule that measured in more than 40 years with absolute perfectly balanced capacitance.
i guess it should sound pretty decent.


what do you think?

 

[kingkorg]

Well you can go either way, but for the price, and what you get (small board with dc-dc converter on each)  + two capsules from it for any project down the line CM60 is hard to beat.

Those boards you linked to all have some issues. Capsule to fet connection should be floating, and one leg of high value resistor.

The latest 3pc lot can be interresting for the price, but should be modded to regular schoeps with FET at Q1 and high value resistors, but it still lacks DC-DC converter, and has to be modded with typical bm800 mod for lower noise.

Edge terminated capsule won't give you correct emulation models if that's what you are going after.

The whole point with 797 capsule is that it's used in real Sphere, and is crazy consistent. The very reason they opted for it. You can ask for a sample directly from 797.

Capacitance consistency is not important, as it affects only output of the capsule in this case, and since the mic is dual output it's irrelevant. All the samples i got from 797 audio were in 3pF tolerance range. Certified with FR graphs 0° and 180°.

So, used B2 + two new cm60. You are looking about 100$.

Studio Project mics, old Rode NT2 (not A) has that capsule as well.

 

[dab0815]

oh you are right that capsule is edge terminated. it was late night yesterday so i didnt catch that.

so i will go with 2 isk and a used b2 pro if i can get one or ask 797 for a sample capsule and get that 30$ body from aliexpress as a body.

ill also look for some fitting 5 pin xlr for outbreak.

thanks! if i got anything and i got some questions regarding getting everything together ill ask you here again

 

[dab0815]

I found a good offef for two SubZero SZC-100 here in europe so ill go with ghese. You said you modded the bias on the circuit for low thd on your mic? Is it necessary?
And should i go with 3 or 6µm for the capsule from 797? I think they offer both?

 

[kingkorg]

When you get reply from them please post here which options you have, and how they look. I have to see them to know which is which, the difference is visual. I can't really remember. There should't be difference in sound really, maybe above 16k.

Sub zero is better option, it's not smd. And there is no need to hustle with bias because Sphere plugin models have their own THD which is anyways higher than your boards. So 0.2% vs 0.01 won't make any difference. Sphere models, and most tube mics are in 1-3% THD when pushed hard.

 

[kingkorg]

You don't want this one
https://images.app.goo.gl/nv38GpfWhfevovaC7

You need this one:
https://reverb.com/item/26869325-microphone-capsule-797-audio-k67-type


And since you are in Europe, you have B2 at Thomann at about 100€.

You can use remaining SubZero bodies and capsule for something like KM84, or for some tube circuit mic.

 

[analogguru]

1 https://www.aliexpress.com/item/1005001830617884.html
this should be higher quality then the ISK / MXL ones right? it also has shoeps circuit. about same price as isk cm60 mic.
version 1 or version 3?

Looks like what can be found inside a t.bone - SC400.  (A used t.bone - SC400 with shockmount can be bought for € 10,--.)

2 https://de.aliexpress.com/item/1005001326599115.html
build after nt1 rode circuit i think. low noise. a bit more expensive than isk cm60

$ 68,-- for a chinese Rode NT-1A-clone pcb ?  :

Since I am "living in Europe" I paid for my two original Rode NT-1A microphones [including the original pcb] € 20,-- each (in a good ("non"-)working condition.  Yes, the sellers tried to run them from 12V-phantom-power [without success] and concluded that they must be broken).

3 https://www.aliexpress.com/item/4001111038259.html
dirt cheap but i dont know what circuit and if it will work

The (already traced) schematic of this pcb's is identical to what can be found inside the BM-700/BM-800/Lollipop/Karaoke-mics.  (For my last BM-700 [in blue] - including foam, metal shockmount, pop-filter, cable and floor stand - I paid € 10,-- alltogether..... I couldn't resist.)
.....
.....

My conclusion:  Don't feed the asian hustlers - there are enough used microphones around for cheap.

 

[dab0815]

When you get reply from them please post here which options you have, and how they look. I have to see them to know which is which, the difference is visual. I can't really remember. There should't be difference in sound really, maybe above 16k.

Sub zero is better option, it's not smd. And there is no need to hustle with bias because Sphere plugin models have their own THD which is anyways higher than your boards. So 0.2% vs 0.01 won't make any difference. Sphere models, and most tube mics are in 1-3% THD when pushed hard.

Thanks i found the thread about the bias upgrade. It was about changing the resistor to 270kohm. But good to know its not necessary.
In that thread the dap-cm-1 was also recommended.

So that leaves me with these option

1. Two cm60 for about 40€ but shipping from china which would take some time

2. Two sub zeros for about 55€ shipping from germany

3. Two dap cm1 for about 70€ which have correct bias for fet circuit.

For the mic/capsule im trying to get a used b2 pro right now and if that dont work out i might buy a new one from thomann

 

[dab0815]

Looks like what can be found inside a t.bone - SC400.  (A used t.bone - SC400 with shockmount can be bought for € 10,--.)
$ 68,-- for a chinese Rode NT-1A-clone pcb ?  :

Since I am "living in Europe" I paid for my two original Rode NT-1A microphones [including the original pcb] € 20,-- each (in a good ("non"-)working condition.  Yes, the sellers tried to run them from 12V-phantom-power [without success] and concluded that they must be broken).
The (already traced) schematic of this pcb's is identical to what can be found inside the BM-700/BM-800/Lollipop/Karaoke-mics.  (For my last BM-700 [in blue] - including foam, metal shockmount, pop-filter, cable and floor stand - I paid € 10,-- alltogether..... I couldn't resist.)
.....
.....

My conclusion:  Don't feed the asian hustlers - there are enough used microphones around for cheap.

Thanks for clearing that up. I just checked pictures and ig seems you are right. 10€ for used sc400 is a steal tho even more 20€ for the nt1a congrats to that.

Btw. What capsules t.bone mic uses? I think they are alctron oems dont they?

 

[dab0815]

You don't want this one
https://reverb.com/item/26869325-microphone-capsule-797-audio-k67-type

You need this one:
https://images.app.goo.gl/nv38GpfWhfevovaC7

And since you are in Europe, you have B2 at Thomann at about 100€.

You can use remaining SubZero bodies and capsule for something like KM84, or for some tube circuit mic.

Whats the difference of ghese two capsules? It seems one has thicker diaphragm and different screws?

 

[analogguru]

....What capsules t.bone mic uses? I think they are alctron oems dont they?

I don't know (and I don't care) who is making the capsules.  There are others around who are experts in detecting the manufacturer.  Here can be seen what is inside a t.bone - SC400:
http://recordinghacks.com/microphones/t.bone/SC-400

and here what is inside a t-bone - SC450:
http://recordinghacks.com/microphones/t.bone/SC-450

 

[dab0815]

Hey KingKorg,
Did you ever had a look inside a t.bone em 700 from thomann? Most likely they are the same mic as the subzero szc 100? Bevause all the other subzero mics and other stuff (like their mic screen etc) are the same as t.bone ..