Delta Sigma




Question:

In your PSU, Dan, you leave space/raise the Fairchild diodes so they sit above the PCB.  Is this necessary for noise or heat?  Or can they lie flush like a resistor?

Hi All, Proudly Presenting the Cinemag BV11 Transformer Many thanks To Dave at Cinemag to take the challenge.
for all  DIY Microphone Requiring a BV11 Style Transformer  8)

For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php

The Cinemag CM-6511 ( BV11 Mic output X-Transformer)


Connection


For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php

Hi All, Proudly Presenting the Cinemag BV11 Transformer Many thanks To Dave at Cinemag to take the challenge.
for all  DIY Microphone Requiring a BV11 Style Transformer  8)

For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php

The Cinemag CM-6511 ( BV11 Mic output X-Transformer)


Connection


For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php

Wow!  Going to have to try one in my other build!  Two m49s - one with AMI bv11 and C type board, and one with B type board and cinemag BV11.  I love flavors!

Phrazemaster

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #285 on: November 06, 2016, 04:02:42 AM »
Hi Dany, did you come to any conclusions about the x-formers you used, Cinemag vs. Ami?

Also, I could not get any information on the Cinemag. I used their contact form but got no response. Are they still selling it, and is it a faithful recreation of the original? Price?

Thanks!

Mike
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** * Kablooie!

North

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #286 on: December 12, 2016, 09:27:33 PM »
If anyone has any leftover TLM49 innards, you can send them my way   :)

Phrazemaster

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #287 on: December 12, 2016, 11:14:07 PM »
If anyone has any leftover TLM49 innards, you can send them my way   :)
Like maybe a spare real Neumann capsule for instance?  ;)
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******************
***************
************
********
*****
** * Kablooie!

North

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #288 on: December 14, 2016, 07:19:00 AM »
Haha ... I was thinking just the electronics ....

Delta Sigma

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #289 on: January 16, 2017, 05:31:24 PM »
Troubles biasing my M49b. I finally got the plate current close and the grid bias at 1.6V. Only issue is the load resistor (R10) is at 56kΩ and the plate voltage is jumping all over.

Is 56kΩ too small for a load resistor? What could be causing the voltage to jump around?

Used Dany's PSU board with choke but bought AMI mic body which meant I had to go point to point.

I bought three rando 5840s from Bowie and one that he tested. I wired up the mic with one of the untested ones and a 100pF cap in place of each capsule in case I made a fatal mistake. My plan was to get numbers where I want them with the first tube then replace it with the tested tube and readjust.

First crack, I had plate current of 0.47mA:

R10=100kΩ
V across R6=1.6V
V plate = 69V
B+ (measured at R10) = 116V
V across R10 = 47V
H+ (measured at Cathode) = 5.6V

I connected a 250k pot with a 56k resistor in series (so I didn't accidentally make R10 = 0Ω). Making R10 higher than 100k decreased plate current . When the pot was at zero (R10=56k), I had a plate current of 77mA but jumping around:

B+ = 113V
V R10 = 37V-49V (bouncing)
V R6 = 1.6V
H+ = 5.9V
R10 = 56k Ω

I didn't adjust the power supply. I'm not sure why the H+ changed. Not exactly worried about that right now.


Delta Sigma

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #290 on: January 31, 2017, 11:53:34 PM »
Switched tubes and found better results for voltages. Fired up the mic and had very quiet signal and a good amount of noise. Got frustrated troubleshooting on acrylic decks (hard to clean tags, hard to swap components). I also wasn't happy with how clean the build was and suspected my wiring. I tore the mic down and rebuilt it with Dany's boards yesterday.

Fired it up today and boom its output is right where it should be. I recorded a few bias settings quickly but only @ 1.65V I had the body screws in. You can really hear the noise without the screws. I was just trying to get a rough idea on where to go as it's time consuming setting the bias and putting everything back together for a test.

I'm not sure which one I like the most from a spoken test. I recorded myself singing with the Bias set to 1.34V (plate current 0.73mA) and I like it but I think I'll be pulling C6 to try and open it up a bit.
« Last Edit: February 08, 2017, 08:26:48 AM by Delta Sigma »

Delta Sigma

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #291 on: February 08, 2017, 08:40:01 AM »
After a multi-day burn in, most noise is gone (H+ @ 6.3V for burn in). I re-set the bias at around 1.2V to get 0.73mA plate current. H+ at 6.0V and B+ 116V.

I removed C6 and the mic really opened up. I removed C4 since Cag of AC701 is 2.2pF adding 8pF to feedback makes sense. The 5840 is 30pF so adding another 8pF seemed excessive. It sounded a lot better with C4 removed. I then added 2pF at C4. It seems that some external feedback is better than none. The mic seems more linear with the 2pF cap in there. It's a Silver Mica but I'll replace it with a ceramic on my next Mouser order.

I ended up putting a 100pF ceramic in C6. It feels better singing into the mic without any C6 but on playback sounds a little untamed.

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If I were to build another M49 (with 5840) I'd start with C4=2pF and C6=100pF set the bias very roughly and burn the tube in for days. I'd then play with the bias and component changes. I really threw myself for a loop by trying to get the bias close before the tube was burned in.
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I also need to try swapping output caps. I have a 0.47uF MP in there. Sounds great but it's probably not wise to stick with the first output cap without trying others.

micaddict

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #292 on: February 08, 2017, 09:13:16 AM »
Quote
It feels better singing into the mic without any C6 but on playback sounds a little untamed.

One of the reasons why singers like the Sony C800g and Manley Ref/Gold so much is because of the extra treble they hear on their cans.  The singer him- or herself hears a lot of low/mid through bone conductance and the extra treble fills this out nicely. It gives  extra clues and confidence.
But for the listener it's different, of course.

Delta Sigma

Re: Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)
« Reply #293 on: February 08, 2017, 07:35:09 PM »
One of the reasons why singers like the Sony C800g and Manley Ref/Gold so much is because of the extra treble they hear on their cans.  The singer him- or herself hears a lot of low/mid through bone conductance and the extra treble fills this out nicely. It gives  extra clues and confidence.
But for the listener it's different, of course.

Makes sense to me! I'm no singer but I felt like a superstar singing into the M49 with C6 removed!

With my M49 parts I finally ordered other feedback cap values for my DIY U67 and compared 100pF (stock) 10pF and no C17. I found the same thing. It felt the best to sing through the mic with no C17 but decided on 10pF listening to playback.

Delta Sigma

More changes. I got a new bag of goodies from Mouser and settled on C6 270pF and C4 1pF. Both ceramics.

lkipod

Hello Dan!

All the content from your Dropbox is missing, do you have a way of making it available again?
That would be terrific!

Cheers

Moshe

it will come back slowly,
hang in there folks ,
actually all of my threads and build thread will come back
Best,
Dan,

wlinart

Does anyone have any experience in modding the TPS100 style PSU for this microphone? What are the necessary mods?

Thanks!
« Last Edit: April 11, 2017, 08:12:34 AM by wlinart »

wlinart

Does anyone have any experience in modding the TPS100 style PSU for this microphone? What are the necessary mods?

Thanks!

I found a schematic of the aphex 460, which apparently is almost the same power supply. Am i right in assuming that changing the zeners for the B+ to the right values will be enough? I would change them to 1N4782A (82V) and 1N4754A (39V)? Or maybe a 1N4753A (36V)?

Thank you!

Hi Dany,
 Are there any component value changes to the original Neumann circuit that are made to accommodate a 5840 tube instead of the AC-701?

 Thank you.


 

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