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

[Ralf]

I seem to be having some trouble with my M49c build: There's some random pops here and there, sometimes it's quiet for hours, then the occasional pops return. Also when I turn the polarity pot too fast I hear the same pops (not a big issue though, I just turn it slow and don't touch it). But the popping and crackling gets really intense when I fumble with the cable connector on the PSU side and give it like half a turn (without disconnecting anything). Then I also start hearing the "ocean wave" sound rising up and settling down slowly again.

I hope it is some kind of connection or grounding issue and not a bad tube, because I have an original AC701 in there.

Recently I discovered that not all of the PSU housing was properly connected to the chassis ground. I was hoping that was the issue and I got the housing connected. But the problem remained and a new problem arose: now I also seem to have a slight ground hum. :/

Can anyone offer some insight here?

 

[EarthTone]

I seem to be having some trouble with my M49c build: There's some random pops here and there, sometimes it's quiet for hours, then the occasional pops return. Also when I turn the polarity pot too fast I hear the same pops (not a big issue though, I just turn it slow and don't touch it). But the popping and crackling gets really intense when I fumble with the cable connector on the PSU side and give it like half a turn (without disconnecting anything). Then I also start hearing the "ocean wave" sound rising up and settling down slowly again.

I hope it is some kind of connection or grounding issue and not a bad tube, because I have an original AC701 in there.

Recently I discovered that not all of the PSU housing was properly connected to the chassis ground. I was hoping that was the issue and I got the housing connected. But the problem remained and a new problem arose: now I also seem to have a slight ground hum. :/

Can anyone offer some insight here?

loose XLR jacks? Low quality connectors at the XLR jack connections?

 

[duantro]

Make sure hi z section is clean from flux

 

[JMPGuitars]

In an effort to get more headroom out of the M49b, I decided to switch to a 5703 tube. I was going to try a 6S6B, but a friend told me they getter better/louder results with a 5703. I did a tube trace comparison on my FUtracer, and the 5703 clearly pushes more current at the same voltages:


Tube 2 and Tube 8 were both 5840W tubes. Tube 8 was the tube previously installed in my M49b, and Tube 2 was the highest current of all my 5840W tubes that I tried. There was a variety of output levels, those two were among the best. The only 5703 tube I had was a clear winner. I am going to get more 5703 tubes, and compare them to some 6S6B tubes I have coming to see how they compare on real traces.

After installing the 5703 tube, I adjusted the heater voltage, and then the B+ and bias. It was helpful having two meters connected at the same time to adjust them.

Here's the mic with the 5703 installed:


Wiring the tube in is much simpler than the 5840W, and the results were a louder, cleaner mic, before even breaking in the tube.

Now my only question is why do people bother with the 5840W tubes at all? 5703 is a better sound, better headroom, and simpler install.

Thanks,
Josh

 

[Recording Engineer]

In an effort to get more headroom out of the M49b, I decided to switch to a 5703 tube. I was going to try a 6S6B, but a friend told me they getter better/louder results with a 5703. I did a tube trace comparison on my FUtracer, and the 5703 clearly pushes more current at the same voltages:
View attachment 115049

Tube 2 and Tube 8 were both 5840W tubes. Tube 8 was the tube previously installed in my M49b, and Tube 2 was the highest current of all my 5840W tubes that I tried. There was a variety of output levels, those two were among the best. The only 5703 tube I had was a clear winner. I am going to get more 5703 tubes, and compare them to some 6S6B tubes I have coming to see how they compare on real traces.

After installing the 5703 tube, I adjusted the heater voltage, and then the B+ and bias. It was helpful having two meters connected at the same time to adjust them.

Here's the mic with the 5703 installed:
View attachment 115050

Wiring the tube in is much simpler than the 5840W, and the results were a louder, cleaner mic, before even breaking in the tube.

Now my only question is why do people bother with the 5840W tubes at all? 5703 is a better sound, better headroom, and simpler install.

Thanks,
Josh

For 49b, I agree with you. Used 6947s in mine and love them! Most definitely has a cool character. But with 49c and variants, 5840W I still like a lot. Went with 5718s in M50c types though. Love them, but they truly take the longest time to warm up every time I’ve used them so far. I wonder how they’d compare to 5703s.

 

[JMPGuitars]

For 49b, I agree with you. Used 6947s in mine and love them! Most definitely has a cool character. But with 49c and variants, 5840W I still like a lot. Went with 5718s in M50c types though. Love them, but they truly take the longest time to warm up every time I’ve used them so far. I wonder how they’d compare to 5703s.

Amplification factors:
5703 = 25.5
5718 = 27
6947 = 35

What specifically do you like about the 5840 in the 49c? I started with the 49c and hated the 5840 so much I switched to the 49b, before realizing the tube just wasn't doing it for me.

 

[Recording Engineer]

Amplification factors:
5703 = 25.5
5718 = 27
6947 = 35

What specifically do you like about the 5840 in the 49c? I started with the 49c and hated the 5840 so much I switched to the 49b, before realizing the tube just wasn't doing it for me.

Besides being relatively-neutral sounding there and quiet with selected a Sylvania, I like how stable it is compared to the 6947 and 5718. This is using AMI BV11R transformers, but also with 6.5:1 transformers without global feedback in the circuit; works great without a hiccup and sounds great.

 

[rmburrow]

In an effort to get more headroom out of the M49b, I decided to switch to a 5703 tube. I was going to try a 6S6B, but a friend told me they getter better/louder results with a 5703. I did a tube trace comparison on my FUtracer, and the 5703 clearly pushes more current at the same voltages:
View attachment 115049

Tube 2 and Tube 8 were both 5840W tubes. Tube 8 was the tube previously installed in my M49b, and Tube 2 was the highest current of all my 5840W tubes that I tried. There was a variety of output levels, those two were among the best. The only 5703 tube I had was a clear winner. I am going to get more 5703 tubes, and compare them to some 6S6B tubes I have coming to see how they compare on real traces.

After installing the 5703 tube, I adjusted the heater voltage, and then the B+ and bias. It was helpful having two meters connected at the same time to adjust them.

Here's the mic with the 5703 installed:
View attachment 115050

Wiring the tube in is much simpler than the 5840W, and the results were a louder, cleaner mic, before even breaking in the tube.

Now my only question is why do people bother with the 5840W tubes at all? 5703 is a better sound, better headroom, and simpler install.

Thanks,
Josh

The late Frank L. Capps used the 5703 (also 6AK4) in the CM2250 mic. Works well. That mic is easy to reskin also.

 

[HerbertR]

In an effort to get more headroom out of the M49b, I decided to switch to a 5703 tube. I was going to try a 6S6B, but a friend told me they getter better/louder results with a 5703. I did a tube trace comparison on my FUtracer, and the 5703 clearly pushes more current at the same voltages:
View attachment 115049

Tube 2 and Tube 8 were both 5840W tubes. Tube 8 was the tube previously installed in my M49b, and Tube 2 was the highest current of all my 5840W tubes that I tried. There was a variety of output levels, those two were among the best. The only 5703 tube I had was a clear winner. I am going to get more 5703 tubes, and compare them to some 6S6B tubes I have coming to see how they compare on real traces.

After installing the 5703 tube, I adjusted the heater voltage, and then the B+ and bias. It was helpful having two meters connected at the same time to adjust them.

Here's the mic with the 5703 installed:
View attachment 115050

Wiring the tube in is much simpler than the 5840W, and the results were a louder, cleaner mic, before even breaking in the tube.

Now my only question is why do people bother with the 5840W tubes at all? 5703 is a better sound, better headroom, and simpler install.

Thanks,
Josh

Okay, sounds good. I will give the 5703 a try. Which tube manufacturer are you using? Herb

 

[rmburrow]

Okay, sounds good. I will give the 5703 a try. Which tube manufacturer are you using? Herb

Raytheon CK5703

 

[JMPGuitars]

Yup, CK5703 is what I put in there. Tomorrow I should have some 6S6B tubes to trace (but won't likely get installed). I'm also going to try some other 5703s to trace out.

 

[OneRoomStudio]

How does the 5703 compare to a 5718?

 

[JMPGuitars]

I've never tried or tested a 5718. But I did make these comparisons today/yesterday after testing 20 6S6B tubes. Somebody commented about 6S6B tubes being more consistent, which is not the case in reality. I'll also be ordering more 5703 tubes to compare a larger set.

Here's all the 6S6B tubes + the highest current 5840W and CK5703:

You can see they're all over the place there.

Here's just the best performers (highest current) vs. the 5840W and CK5703:

In the voltage range we're targeting for the M49, it's a tight match between the 5703 and 6S6B, with the 5840W feeling like Internet Explorer vs Chrome/Firefox. It's just not competing.

Thanks,
Josh

 

[JMPGuitars]

Well, this is interesting. I can't say for certain if this is batch specific, or model specific, but it seems the 5703WB are going to be lower output than the rest:

 

[donivan]

has anyone had pops when changing patterns
would it be in the switch design itself?

 

[imo]

Mini saga with nice ending. I bought a body thinking the Poctop PCB would fit, but they didn't..Got a Tab body and disk set, built a mic with that, and then still had the first body. Finally, I found a way to get the PCBs in the body with a lot of work. When I got everything connected, I had a large 100hz hum. I figured it was in the mic with all of the work I had done, so I took it apart, checked everything, cleaned the heck out of it, and put it back together. Still hummed. Decided i would try my other power supply, which of course, had different connectors, so I disassembled and reassembled the 2 cords and tried the mic with the other power supply...Dead quiet..hmm.
So, I sat with the power supply for a while. I had initially tested it for DC voltage and got my voltages right, so I assumed everything was good, I did look at the HT rail for AC but never looked at the heater voltage. When I put the meter on for AC, I saw almost 5V! Well, that explains why the tube was glowing. I sat there for a while, thinking I would have to replace some caps or resistors. I probed around a bit, and saw AC voltage on the ground side of the first .1 cap on the heater rails. Wow, so need to check for ground. Took the board out, and looked underneath to see if any caps were not properly seated..Nothing. But there was no ground reference on the whole heater ground side. I looked at the board for 30 minutes, trying to find any cracks, but it looked perfect. Totally baffled as to what happened there. I took a wire from one of the big cap negative to the 0V section where you star ground and voila, everything fell into shape.

So, I have 2 nice sounding M49C style mics, one with the acrylic boards, and one with the PCB set. Both moby bV-11 transformers, 2 Solilloqueen flat 47 capsules. The PCB one has the capsule sitting a bit higher. Played a little bit with sound. It had a bit more high mids, which are probably where its sitting in the headbasket. Pretty similar in overall EQ. I don't have an easy way in studio to test for frequency response, but using my DAW and an EQ with a spectrum analyzer on my voice shows a push around 200hz with a roll off around 100hz and a nice response through mids and highs. I definitely dig this capsule.

 

[RuudNL]

https://groupdiy.com/threads/neuman...lm49-conversion-to-m49-b-c.51862/post-1045370
A year later and BeesNeez is still producing the (B)M49, Flea has the '49' ("a replica of the Neumann M 49") and other brands (Golden Age Premier, Upton etc.) even produce the "ELA M251.
So I am not too worried about the numbers.

 

[EarthTone]

Mini saga with nice ending. I bought a body thinking the Poctop PCB would fit, but they didn't..Got a Tab body and disk set, built a mic with that, and then still had the first body. Finally, I found a way to get the PCBs in the body with a lot of work. When I got everything connected, I had a large 100hz hum. I figured it was in the mic with all of the work I had done, so I took it apart, checked everything, cleaned the heck out of it, and put it back together. Still hummed. Decided i would try my other power supply, which of course, had different connectors, so I disassembled and reassembled the 2 cords and tried the mic with the other power supply...Dead quiet..hmm.
So, I sat with the power supply for a while. I had initially tested it for DC voltage and got my voltages right, so I assumed everything was good, I did look at the HT rail for AC but never looked at the heater voltage. When I put the meter on for AC, I saw almost 5V! Well, that explains why the tube was glowing. I sat there for a while, thinking I would have to replace some caps or resistors. I probed around a bit, and saw AC voltage on the ground side of the first .1 cap on the heater rails. Wow, so need to check for ground. Took the board out, and looked underneath to see if any caps were not properly seated..Nothing. But there was no ground reference on the whole heater ground side. I looked at the board for 30 minutes, trying to find any cracks, but it looked perfect. Totally baffled as to what happened there. I took a wire from one of the big cap negative to the 0V section where you star ground and voila, everything fell into shape.

So, I have 2 nice sounding M49C style mics, one with the acrylic boards, and one with the PCB set. Both moby bV-11 transformers, 2 Solilloqueen flat 47 capsules. The PCB one has the capsule sitting a bit higher. Played a little bit with sound. It had a bit more high mids, which are probably where its sitting in the headbasket. Pretty similar in overall EQ. I don't have an easy way in studio to test for frequency response, but using my DAW and an EQ with a spectrum analyzer on my voice shows a push around 200hz with a roll off around 100hz and a nice response through mids and highs. I definitely dig this capsule.

Sweet! Nice going. Hey I’m wondering, did you have one of the ShuaiYin m49 bodies? If so, how did you get it to fit Dany’s PCB’s boards into it? I’m still hoping for a solution to making these 60mm pcb’s fit into that 55mm chassis. Haven’t been able to figure it out yet.

 

[imo]

Sweet! Nice going. Hey I’m wondering, did you have one of the ShuaiYin m49 bodies? If so, how did you get it to fit Dany’s PCB’s boards into it? I’m still hoping for a solution to making these 60mm pcb’s fit into that 55mm chassis. Haven’t been able to figure it out yet.

I responded to this in PM, but wanted to also post the info here, as this can be confusing to someone looking to build the 49 design. I have a body from Micandmod. I bought it after writing to Poctop, who thought the bodies would work. They don't! I tried dremeling the sides and using plexi disks and a standoff kit. I ended up cutting through a trace that I couldn't see. I was able to fix it, but when i took some time to think about it, it made more sense to build the circuit with the Micandmod PCB. They only do the C version, as does the Tab kit, so if you want to build a B circuit, I don't have an easy route.

One point of note with the Micandmod kits. They design these builds to be foolproof so a beginner can have a working mic. That assumes you are using their whole kit, with power supply and cable as well. In my case, I was using Dany's power supply and my own cable. They don't have a component layout, or schematic that references part numbers, so if you are trying to build it with any changes, as I did, it is actually more confusing than a scratch build. In my case it took a lot of time in coming up with my own understanding of how their layout corresponded to the 'C' schematic. The mic body comes with an XLR that is already pre wired, but the wiring they use doesn't work with the power supply I had.

In the end, it was fine, though a lot of extra work I could have avoided had I known. Hopefully this information can help someone else avoid that

 

[duantro]

I’ve got a handful of leftover Poctop m49 pcbs for the same reason. Ended up using tab funkenwerk acrylic boards for a pair and a vami sound set on one. Fit great.