Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #700 on: May 28, 2012, 07:39:41 PM »
Hi all!
I just completed my three microphones and I'm VERY pleased with the sound! One concern though is the output level. In comparison to my u89 the output is way lower. Singing softly into it needs full gain from my API 2488 preamps for a proper input to ProTools. The files from the clones are a bit noisier than the files from the u89 but only because of the preamp from what I can hear. The mike itself seems to be quiet. I know its been a topic here but i just wanted to confirm that. Anybody having any real trouble with noise in actual recording situations? 
Seems to e a lot smoother compared to the u89 sound wise. As stated earlier in this thread, very vintage sounding. Great! in other words. I'll put them to test in my next sessions.

There's also an annoying pop when i change between omni, card, 8 and also when I engage the hipass and pad. Also a slight tendency for resonance in the body. When holding the u89 the handling noise is very low frequency. The clones are more midrangey, perhaps caused by the different housing. Any ideas?
Im using peluso capsules and ami transformers.
The body is perhaps not historically correct but I thought the looked cool!
Thanks for all your help!!!
Let's all get together for a beer some time!  :)

congrats, your mic body are simply awesome,  great Job looks even more  vintage imho  8),  don't worry about the poping when switching ,  my real vintage does exactely the same thing no exception , as for the output, the vintage u87 put out the same output , i did some compare with my build with the original trafffo and it is virtually the same output level at same gain ,  it will be indeed about 10db lower output than the modern version.

Thanks for your post,

Best
Dan,


mylesgm

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #701 on: May 28, 2012, 11:22:35 PM »
which Mic bodies are those?
Check my work at www.mylesmumford.com

kante1603

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #702 on: May 29, 2012, 12:55:14 AM »
Hi,

congrats to your builds.
Switching patterns causing a pop is normal,remember you switch the second part of your capsule in and out.Even modern U87A types do so.
Soundwise you can not compare them to a U89 since this is a totaly different microphone.
The level drop compared to U87A version is -11dB from the math.

Udo.

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #703 on: May 29, 2012, 06:06:08 AM »
Hi,

congrats to your builds.
Switching patterns causing a pop is normal,remember you switch the second part of your capsule in and out.Even modern U87A types do so.
Soundwise you can not compare them to a U89 since this is a totaly different microphone.
The level drop compared to U87A version is -11dB from the math.

Udo.

Thanks for your reply! And for your earlier posts that have been very helpful!

-11db seems to be in the ballpark of what I'm experiencing here. Great sounding microphone. I must say I did to expect them to be this good.
Actually I hade a hard time hearing any difference between my u89 and a new u87 in a session last summer. Male vocals. The 87 was a bit brighter, cleaner and better shape capsule?, but otherwise pretty close. The guy singing couldn't tell the difference at all! That's why I used the 89 for reference. A friend of mine has got a vintage 87 that's will compare my clones with. I'll post the results here ASAP.
/
Emil

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #704 on: May 29, 2012, 06:08:22 AM »
which Mic bodies are those?

They are from a thomann retro tube II. Pretty cheap mike still including a pretty descent shock mount.
/
Emil

kante1603

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #705 on: May 29, 2012, 09:06:50 AM »
Hi Emil,

Cool,a comparison to a vintage type is most useful for us!
Concerning comparison between an actual U87a and an U89:Something must have gone completely wrong,they absolutely don't sound equal or close to each other.Maybe the 89 is in a worse condition than the 87A?I have worked with both of them for ages and I swear they are very different in comparison,an U89 normally has a faster resonse,different mid range like more linear,different highs etc.Also it's capsule is smaller.

Just for info,have fun with your new toys,

Udo ;)

sr1200

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #706 on: May 29, 2012, 09:38:32 AM »
If someone wanted to bring the mic level up say 6db or more, what would have to change in the circuit/transformer?
MEI Studio - Long Island, NY: http://www.meirecords.com

tskguy

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #707 on: May 29, 2012, 03:03:19 PM »
My first How its made video :)
;D



Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #708 on: May 29, 2012, 05:18:36 PM »
My first How its made video :)
;D


sweet!!!

kante1603

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #709 on: May 29, 2012, 08:06:22 PM »

Thanks for all your help!!!
Let's all get together for a beer some time!  :)
Where are you located Emil? ;D
Cheers,
Udo.


HellfireStudios

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #710 on: May 30, 2012, 09:32:00 AM »
Nice CNC. The kind of stuff you can do with that makes me jealous. The Sony C800G capsule is where I would start. The mic is far too expensive for most, and I would befirst to in line to pick up a clone capsule. *hint, hint*
Cool stuff. How do you test a capsule to make sure it falls within spec? The only reason I ask is that Neumann supposedly rejects about 70% of their capsules, and the Telefunken R-F-T line supposedly rejects about 30%. I assume, in Neumann's case, they go back for re-skinning if defective. Just curious. Thanks.

-James-
"Tommorrow is just yesterday in reverse. Just like friends are enemies in reverse." -Gary Busey

burglar

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #711 on: May 30, 2012, 11:38:46 AM »
Hi Poctop

It's going to be a couple months before i can get to work on the PCB's I've ordered but I was wondering if you have any plans to do a more comprehensive build guide and or wiring diagram for the 2 transformers & capsules you recommend, + a calibration guide would be very useful.  I'm confident I can populate the boards painting by numbers and I plan to use the AMI tranny but I'm a total beginner and a wiring guide would be a huge help. 

If anyone else has some literature that might make this a bit easier it would be much appreciated.  This is my first project away from all inclusive kits.  Sorry for the newbism.   
« Last Edit: May 30, 2012, 02:52:00 PM by burglar »

tskguy

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #712 on: May 30, 2012, 01:30:21 PM »
Hellfire,

I have some steps that I take to make sure things are consistent. In terms of tuning there are ways to verify the resonant frequency as well as the capacitance after it is skinned. Those are the most important things you can measure after skinning. The other factors are accuracy and repeatability during the machining process, this is key for consistency over multiple capsules.
My CNC is accurate to .001 mm and holds that very well. The back plates I am making are absolutely identical to the original k87 back plate I have access to, the only difference with my capsule will be the outer rings and the screws holding it down. I chose to use stainless 0-80 thread screws instead of the less common 1.1mm size screws Neumann uses. To be honest it will have no effect on the sound as well as being much easier to machine! Every other part is the dimensionally the same.  I have also had the pleasure of gaining a wealth of knowledge from a long time capsule repairman, he has provided me with a large number of tips and tricks to help be as consistent as possible.  It is for sure a black art! ;)

Eric

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #713 on: May 30, 2012, 04:21:02 PM »
Hi Poctop

It's going to be a couple months before i can get to work on the PCB's I've ordered but I was wondering if you have any plans to do a more comprehensive build guide and or wiring diagram for the 2 transformers & capsules you recommend, + a calibration guide would be very useful.  I'm confident I can populate the boards painting by numbers and I plan to use the AMI tranny but I'm a total beginner and a wiring guide would be a huge help. 

If anyone else has some literature that might make this a bit easier it would be much appreciated.  This is my first project away from all inclusive kits.  Sorry for the newbism.   

Make Sure you read all the build thread and white market thread as we have spread some info there as well  and download all the file from the white market page there is instruction on how to proceed but this is not that hard to make ,  basically you populate the boards and follow the pointer given in the excel file then you tune the FET and install the linked boards in the mic boady and then connect the capsule and enjoy the mic , again there is a lot of info on the construction in this thread and also in the white market thread ,

Keep me posted if you need any other hints ,

cheers,
Dan,
 

burglar

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #714 on: May 30, 2012, 04:36:47 PM »

Ok, thanks Dan.  I'll let you know how I get on.  That was a nice re-assuring post.  Smiley face.

HellfireStudios

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #715 on: May 30, 2012, 05:16:27 PM »
Hellfire,

I have some steps that I take to make sure things are consistent. In terms of tuning there are ways to verify the resonant frequency as well as the capacitance after it is skinned. Those are the most important things you can measure after skinning. The other factors are accuracy and repeatability during the machining process, this is key for consistency over multiple capsules.
My CNC is accurate to .001 mm and holds that very well. The back plates I am making are absolutely identical to the original k87 back plate I have access to, the only difference with my capsule will be the outer rings and the screws holding it down. I chose to use stainless 0-80 thread screws instead of the less common 1.1mm size screws Neumann uses. To be honest it will have no effect on the sound as well as being much easier to machine! Every other part is the dimensionally the same.  I have also had the pleasure of gaining a wealth of knowledge from a long time capsule repairman, he has provided me with a large number of tips and tricks to help be as consistent as possible.  It is for sure a black art! ;)

Eric

I appreciate the info. Sounds like you know what you're talking about. I'm sure it puts anyone considering your capsule at ease to know they're not just slapped together. Thanks.

-James-
"Tommorrow is just yesterday in reverse. Just like friends are enemies in reverse." -Gary Busey

tskguy

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #716 on: May 30, 2012, 08:36:59 PM »
Thanks Hellfire, So how many do you want??? ;D ;D ;D ;D

Matador

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #717 on: May 31, 2012, 04:16:52 PM »
Just a note on the tone of the U87 vs. other mikes:  I've A/B'd this Aurycle mike with the K67-type capsule in this circuit against others like the C12 tube design and various other Schoeps-like designs. 

What I find is that if you go head-to-head against mikes that do not de-emphasize the upper frequencies (like everything above 6kHz), the U87 tends to sound "dull" in comparison.  However in a mix (especially mixes that are denser than just singer/songwriter and acoustic guitar), I find that the U87 just "drops right in" with very little tweaking.  In fact, I've found that the U87 in cardioid just puts the vocal in the exact right spot for a modern rock mix, where the meat of the midrange is where the vocal sits, but the air is removed to not interfere with the cymbals and other high-transient material.  For an every more laser-focused midrange sound (like heavy rock with 4 doubled guitar parts), the SM7 works even better, but the U87 is very close.

Every time I've tried to use my C12 in this situation I've always had to low pass filter it to get it to sit just right, whereas I know with the U87 is probably will "just work" with minimal tweaking during the mix.  The high end is there, it's just not pronounced enough to get in the way of anything else.

Of course the magic of recording is capturing the essence of each part that will work well when mixed together, given the restrictions of the frequency content that each part is occupying.  This is why I pull out the C12 when I need to capture the air, and the U87 when I don't.  It's one less plugin and one less hassle for me later. ;)  However when set up head to head on a single source I've almost always preferred the C12 because it seems to be the best "DC to microwaves" kind of sound (to steal Ethan Winer's line) that works on every single isolated source you can possibly find. 

It just doesn't always work best in the mix....

If someone wanted to bring the mic level up say 6db or more, what would have to change in the circuit/transformer?

I've been thinking about this too.  The three main areas are:

1) Increase gain in the JFET front end:  if you pull more current through the JFET, we can theoretically swing more output signal for a given delta input signal (e.g. the slope of the load line increases).  However the only way to pull more current through the JFET is to pull that current from the phantom supply, which drops the polarization voltage available to the capsule (because the increased current drops more voltage across the 2K21 resistors).  Less polarization means less sensitivity which means less apparent gain, so it's ultimately self defeating.

The only way to combat this is to use a charge-pump-like circuit to increase the polarization voltage (which decouples the polarization voltage from the current being used in the rest of the circuit), which requires a whole new circuit.  This is exactly what Neumann did with the U87AI.

2) A far easier way to is add a PNP follower after the JFET.  This reduces the output impedance of the JFET stage from 40k-ish down to several hundred ohms.  This means you can use a transformer with a much smaller ratio, which means less voltage loss.  Even moving down to a 5:1 BV11P-type would give you back the 6dB of signal you are looking for.  Ideally you could use a 2:1 transformer which would give you back 14dB.

This is how the stock Aurycle circuit works (although they use an NPN follower and cap couple it for some reason), but it sounds slightly different.  The highs are more present, and the mike responds much more to sharp transients like pick attacks on acoustic guitar:  the mike sounds less U87-like, if that makes any sense.  I think part of the mellow U87 sound comes from the high output impedance driving the high-ratio transformer.  It's subtle, but it's definitely different.

3) Reduce negative feedback:  as I hinted at earlier in the thread, you can decrease the value of C6 (or remove it entirely) and it will give you back 3dB to 6dB, however the sound also changes as well.  If you like the "EQ-ed" sound, lowering C6 will take that away, however the mike will be hotter.  If you like/want the "air" it's a very simple mod to do and doesn't require any expensive or complicated circuit changes.  The sound change is FAR more drastic than #2 above (removing C6 can make it sound like a completely different mike).

sr1200

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #718 on: May 31, 2012, 04:47:28 PM »
Matador, awesome read man.  So for #3 youre saying just clip out c6... do you replace with a jumper or just leave it out entirely (im at work now, and done have the schemo infront of me atm).  This would seem the only viable options being i dumped a nice chunk of change into the TAB transformer. 

MEI Studio - Long Island, NY: http://www.meirecords.com

Matador

Re: Neumann U87 Vintage Circuit Build Thread.
« Reply #719 on: May 31, 2012, 07:43:27 PM »
Matador, awesome read man.  So for #3 youre saying just clip out c6... do you replace with a jumper or just leave it out entirely (im at work now, and done have the schemo infront of me atm).  This would seem the only viable options being i dumped a nice chunk of change into the TAB transformer.

Just remove it, don't jumper across it.  You can probably reheat the solder to get it out should you decide you don't like it and want to put it back.

Or if you are careful, you can snip one side, then move the cap over a little bit and place a piece of electrical tape over the part left in the board.  That would make it easier to solder back.


 

Related Topics

  Subject / Started by Replies Last post
0 Replies
2740 Views
Last post March 12, 2012, 11:30:21 PM
by poctop
801 Replies
197664 Views
Last post July 17, 2019, 04:03:26 AM
by Spencerleehorton
338 Replies
83964 Views
Last post August 07, 2019, 03:20:39 PM
by Rlucas41
3 Replies
1249 Views
Last post April 02, 2018, 05:30:35 PM
by Wordsushi