Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)

[Moby]

Understood and thank you, Srdjan. I'm using 6S6B-V's and they are all about the same noise level out of the 5 or 6 I've tested. Maybe it's worth trying some 5718ws's?

I have the PSU from Dany's kit so I believe it's unregulated. The cap doesn't appear leaky but it's probably better to not risk it in this case...

From my experience 6s6b's are good low noise tubes. But yes, you can also try other like 5718. I'm not familiar (in details) with Dany psu arrangement but measure the voltage unloaded and if exeeds 150v stay away from the 160v capacitor.

 

[egroys]

Just to be clear, you mean the B+ voltage, correct? And is there anything else I can check/do in terms of noise, or at this point is it just the circuit?

 

[Moby]

Just to be clear, you mean the B+ voltage, correct? And is there anything else I can check/do in terms of noise, or at this point is it just the circuit?

Yes, anode voltage. At the psu, withouth the load of the tube.
I'm afraid that you can't do much but good PSU filtration (hum) and low noise tube selection.

 

[rmburrow]

Yes, anode voltage. At the psu, withouth the load of the tube.
I'm afraid that you can't do much but good PSU filtration (hum) and low noise tube selection.

I like the Neumann NKM type supply where a gas voltage regulator tube is connected across the HT in series with an 8 k resistor off the HT rectifier. The regulator is a 150B2 (a 0A2 American will work with wiring change) which limits the DC voltage to the filter caps to 150 volts regardless of the HT load. 0A2's are inexpensive compared to the 5840, 6072, etc. I use rechargeable 1.5 v AA batteries in place of the "stabilytes" in the NKM. To power a 5840, the 4 volt DC heater supply must be increased to 6 volts with a wiring change, and 4 "AA rechargeables" in series regulate the heater supply for a 5840.

 

[egroys]

Yes, anode voltage. At the psu, withouth the load of the tube.
I'm afraid that you can't do much but good PSU filtration (hum) and low noise tube selection.

I have 138V unloaded at the PSU. Do you think that's too risky for that Soviet NOS rated at 160V?

 

[Moby]

I have 138V unloaded at the PSU. Do you think that's too risky for that Soviet NOS rated at 160V?

I's really tight.since i'ts PIO NoS I really can't be sure. Generally speaking those guys can handle more than 160v but who knows?

 

[ZHOUJUN]

terribly sorry
I take back my previous statement about the insufficient low frequency of the 5718 used in the M49C circuit. I now feel that the 5718 is richer and fuller in the mid-low frequency than the 6S6b and 5840. The 6S6b feels that the mid-frequency is too prominent, and the 5840 low frequency is a bit lacking. I used MOBY's BV11 and Moby's T14 for testing, no big differences were found.

 

[egroys]

I just received a ready made M49 PSU from China. I purchased a body and yoke directly from Jenny and they were offering PSU's for $55 so I couldn't resist. I am curious, since these appear considerably different than my poctop ones, if I should change/upgrade any components? There are no trimmers here but there is also a voltage regulator. I will likely update the 7 pin wiring to match Dany's standards for interchangeability.
Please let me know your thoughts and recommendations!

 

[Migs 31]

if I should change/upgrade any components? There are no trimmers here but there is also a voltage regulator. I will likely update the 7 pin ...

Hi,
I think I got exactly the same (well... Thomas ordered them for me )from Jenny, with a M49 & their great Yoke.

Could you share what’s written on the front of the metal box ? Is it PS-2 ?

You say « there is a regulator » From the top of my head that would be for the 6.3V heater. The HT will be at the bottom left of your PSU (on first pic) coming out of those two 1N47** diodes, like most Chinese Power supplies. And it will need filtering and/or correct grounding scheme.

Check it really is 120V at HT output.


M

 

[egroys]

Hi,
I think I got exactly the same (well... Thomas ordered them for me )from Jenny, with a M49 & their great Yoke.

Could you share what’s written on the front of the metal box ? Is it PS-2 ?

You say « there is a regulator » From the top of my head that would be for the 6.3V heater. The HT will be at the bottom left of your PSU (on first pic) coming out of those two 1N47** diodes, like most Chinese Power supplies. And it will need filtering and/or correct grounding scheme.

Check it really is 120V at HT output.


M

It doesn’t say it on it but it’s their ‘PSU-3’

What sort of filtering would I need to add?

 

[Migs 31]

It doesn’t say it on it but it’s their ‘PSU-3’

What sort of filtering would I need to add?

Oh wow, $55 for that ? Thats a great deal!
You have the upgraded "pimp" version. I got the PSU-2, both PCB's look VERY similar.
Is that putting out 120V on HT pin ?!? Check it please.

So conc. filtering. @RuudNL , @abbey road d enfer and @Khron go on in depth and better words than what I could ever say to you, in the first two pages of this thread:

https://groupdiy.com/threads/heater-voltage-filtering.80421/page-2

and this great piece of advice on post number 75 by Ruud:

https://groupdiy.com/threads/m49-oliver-archut-alt-version.79640/page-4#post-1096996

M

 

[ZHOUJUN]

I once made a detailed comparison between Jenny's $55 M49 PSU and Andreas Grosser's retro M49 PSU and Neumann u67 psu. I found that the $55 PSU is simply a great value. It has a standard B+120V and a heater of 6.3V. If used for D49, Only need to change the connection of 7 PIN pins.

 

[egroys]

I once made a detailed comparison between Jenny's $55 M49 PSU and Andreas Grosser's retro M49 PSU and Neumann u67 psu. I found that the $55 PSU is simply a great value. It has a standard B+120V and a heater of 6.3V. If used for D49, Only need to change the connection of 7 PIN pins.



View attachment 140808View attachment 140809View attachment 140810View attachment 140811

That’s great to know! Did you add/replace anything such as trimmers for B+ and H+?

 

[soliloqueen]

the m49 body and power supply are both absolutely great. The PSU pictures required no mods. It's good enough that even a few boutique manufacturers I know are considering using it as-is. They even have some pretty good QOL changes from the originals. It's well-engineered. My personal theory is that Neumann is sending cease and desist orders to all the big mic companies over the M49. I think a big player (TFunk USA or maybe Golden Age Project) was forced by Neumann to cancel an M49 before it was announced at NAMM. The factory is now selling off the parts they had finished to try to recoup costs. That's the only explanation for such a perfect M49 body (even the mesh gauges and orientation are accurate) and power supply appearing out of nowhere. This sucks for whoever had to cancel such a high-investment microphone after it was effectively finished, but it's great news for us, as we now get a $4-figure-level body and power supply at liquidation prices...

 

[Murdock]

the m49 body and power supply are both absolutely great. The PSU pictures required no mods. It's good enough that even a few boutique manufacturers I know are considering using it as-is. They even have some pretty good QOL changes from the originals. It's well-engineered. My personal theory is that Neumann is sending cease and desist orders to all the big mic companies over the M49. I think a big player (TFunk USA or maybe Golden Age Project) was forced by Neumann to cancel an M49 before it was announced at NAMM. The factory is now selling off the parts they had finished to try to recoup costs. That's the only explanation for such a perfect M49 body (even the mesh gauges and orientation are accurate) and power supply appearing out of nowhere. This sucks for whoever had to cancel such a high-investment microphone after it was effectively finished, but it's great news for us, as we now get a $4-figure-level body and power supply at liquidation prices...

Which body exactly are you talking about? The one pictured in egroys post?

 

[soliloqueen]

Which body exactly are you talking about? The one pictured in egroys post?

yes, i believe so

 

[Murdock]

But isn’t that the same body AMI and Chunger were offering for some time now?

 

[soliloqueen]

But isn’t that the same body AMI and Chunger were offering for some time now?

yes perhaps i'm getting them mixed up

 

[ZHOUJUN]

That’s great to know! Did you add/replace anything such as trimmers for B+ and H+?

Did not change any circuit or components. I specially soldered a wire for testing. only needed to adjust the position of the 7PIN male pin according to the wiring sequence of M49C.

 

[RuudNL]

Do these power supplies still have a 7806 regulator + diode for the filament voltage?
(Effectively producing a voltage of 6.7 V...)