Warm Audio WA-67 - Teardown

[moamps]

Makes one wonder just how they made the (what are usually plated) through-hole vias, to connect the top and bottom copper layers...

Maybe that PCB is gold plated and the joints between the top and bottom are made of gold. In any case, it cannot be compared to a beginner's home-made PCB. Soldering joints that look worse are most likely the result of using 0% Pb solder.
I have seen several faulty microphones with a similar malfunction in my working life, from dynamic AKG, Shure, Sennheiser to LDC condenser and ribbon. The reason was always too much G factor. Falling off a stand or during transport, and I don't see much need to be done about it. As for the production itself, one only has to ask whether this microphone justifies the price of 1000Eur with its sound (and name), which is about 6 times less than the Neumann U67.

P.S.
The technology of making PCBs for high-impedance circuitry in condenser microphones requires a different approach than usual. Eg. solder masks, prints, coatings can significantly compromise the insulation between soldering points. Teflon-insulated pins are often used here.

 

[Khron]

Even if it was gold plated, iirc you need several layers of other plating, to get the gold to properly adhere; i kinda doubt one can plate gold straight onto fiberglass / PCB substrates.

Copper needs nickel plating before gold plating, if my memory isn't far too mistaken.

Soldermasks / other prints CAN be removed in the gerber files - i've done that on some of my boards that i've had manufactured in the far east.

 

[Whoops]

BODY RINGING

I found why the microphone had an horrible mechanical ringing, it's due to the tube parte of the body, it rings like a Bell.
I did a video showing the ringing and comparing it to a U87 body (same body as U67).
There's terrible ringing in the WA67 tube, I don't know if this presents a problem while recording or not, but I will try to dampen the body.
With the U87 there's some resonance, lower in volume but no Ringing, it sounds dampened.

please let me know if you guys can view and listen the video in your browsers.
Somehow in my browser it doesn’t open

If you can’t open it let me know and I will upload it to Youtube

 

[stevenshen2210]

This is the WA67 PCB right next to a home etched Bo Hansen DI PCB I’ve made.
The PCBs look the same,
I find it strange Warm Audio didn’t do a professionally made PCB, even though quality PCBs are pretty cheap, it makes me think there’s someone in a basement in China home-etching these pcbs by hand.
Really strange

View attachment 88329

I think it might be Warm Audio want to copy the look of those PCBs in an old U67 because the PCBs in an old U67 looks somewhat similar to the Warm audio's... I reckon it would be cheaper for Warm audio to get the PCB done properly than what they are doing right now.

Also, I am just wondering what happens if you replace the capsule in the WA67 with a 797 audio one.

 

[wave]

please let me know if you guys can view and listen the video in your browsers.
Somehow in my browser it doesn’t open

If you can’t open it let me know and I will upload it to Youtube

Whoops,
When I click the link or open in a new window/tab the vid is permanently muted... I have experienced the same thing with those bodies.
One thought I had is: you can absolutely get PCBs with no soldermask, silk...etc from the PCB fabricator. PCBWay lets you order like this as well as others. So it's probably mass produced but with no mask. They probably did this in an effort to be more like the originals which always looked to me to just have some sort of clear coat on them...

 

[RuudNL]

Just imagine: Neumann producing a microphone that looks like this...

 

[pucho812]

As always, I am reminded of the quote
The design is in the details.

 

[JMc]

I have the WA-67 and haven't torn into it because I'm not having any problems with it and actually think it sounds amazingly good, especially for the price I paid, but that said, I also recently bought (and promptly returned) a WA-47Jr because of the horrendous ringing from the mic body. It was so obvious when speaking into the mic, and lightly tapping the mic body confirmed it. I was also unimpressed that the back side of the capsule sounded considerably darker and denser than the front of the capsule in figure 8 mode. Both sides should ideally sound identical, no? WA claims to have sold 10,000 of the 47jr and seemed surprised to hear my critique when I made them public. It seems that most are being used to mic kick drums or toms and so it stands to reason that the ringing wouldn't be as noticeable, given that the drums themselves have a ringing decay that probably masks and lasts longer than the mic body ringing. I also bought a WA-47 and compared it with my MK-47 I built with a Thiersch PVC M7 capsule about 11 years ago. I got a great deal on the WA-47 - factory sealed, brand new for $689 and honestly, I spent more in parts for my MK-47 project and to my ears, the WA sounds slightly better than my MK-47, which I have always loved. So again, if WA is "cutting corners", to save cost, they seem to be cutting the right ones (for the most part), IMO.

 

[kingkorg]

I was also unimpressed that the back side of the capsule sounded considerably darker and denser than the front of the capsule in figure 8 mode.

I had that mic, and both sides measured identically in f8 mode. I hope you haven't been listening to your own voice while wearing headphones?

When it comes to the ringing, idk if you read my post but that comes from a loose coupling cap. Small details like that can be a such dealbreaker.

Otherwise that capsule in 47jr is wonderfull, headbasket shape ruins it, alters the sound in wrong way.

 

[Whoops]

Just imagine: Neumann producing a microphone that looks like this...

Neumann produces really crap stuff, like the M149 microphone, it looks worse than this.
Advertized as a tube mic and then it's an hybrid design with FETs and opamps. Only the audio from the front diaphragm passes the tubes, so no tube for Omni or Fig of 8.
Look at this tube:

The PSU of the M149 is much worse than any product Warm Audio makes, and they sell it for $1000
it has a cheap, probably Chinese also switching PSU module inside and it's assembled as what looks a crappy DIY job
For Neumann's name and for the $1000 this is somewhat shamefull.
Neumann was for sure a Great and outstanding company, but that was many years ago...

 

[Whoops]

I have the WA-67 and haven't torn into it because I'm not having any problems with it and actually think it sounds amazingly good, especially for the price I paid, but that said, (...) So again, if WA is "cutting corners", to save cost, they seem to be cutting the right ones (for the most part), IMO.

I also think the WA67 sounds pretty good, and for the price I think it's a great buy.
But while I had to open the mic to replace the broken capsule mount I decided to investigate a bit deeper and check if there's something to be improved.

At the moment damping the body to reduce the ringing, re-touching all the soldering and thinning the copper traces will be high on my agenda

 

[Whoops]

Whoops,
When I click the link or open in a new window/tab the vid is permanently muted...

I uploaded the video to Youtube,
please try it now

WA67 BODY RINGING

 

[Whoops]

One thought I had is: you can absolutely get PCBs with no soldermask, silk...etc from the PCB fabricator. PCBWay lets you order like this as well as others. So it's probably mass produced but with no mask.

Yes, thats probably right,
it's probably done in a factory although it looks this way.
There's through-hole vias, to connect the top and bottom copper layers so it was not etched

 

[pinchemotherloaf]

BODY RINGING

I found why the microphone had an horrible mechanical ringing, it's due to the tube parte of the body, it rings like a Bell.
I did a video showing the ringing and comparing it to a U87 body (same body as U67).
There's terrible ringing in the WA67 tube, I don't know if this presents a problem while recording or not, but I will try to dampen the body.
With the U87 there's some resonance, lower in volume but no Ringing, it sounds dampened.

That might be a feature to replace a tuning fork at the session. That's a perfect high 'E'

 

[Whoops]

That might be a feature to replace a tuning fork at the session. That's a perfect high 'E'

 

[3nity]

Very interesting thread.
I always wanted a true and honest review of those mics..I'm not buying any..Im presently building a D-U67!

 

[RuudNL]

Neumann produces really crap stuff, like the M149 microphone, it looks worse than this.
Advertized as a tube mic and then it's an hybrid design with FETs and opamps.

Yes, the Neumann M147 and M149 are the strangest designs I have ever seen!
A tube (with the type number removed!), transistors and an IC.
Not to mention the 'cheapo' power supply.
But you will never see stacked capacitors covered with goop to keep everything together...

 

[ratrace]

At the moment damping the body to reduce the ringing, re-touching all the soldering and thinning the copper traces will be high on my agenda

I would be curious how you plan to damp the body?

i got 3 bm800 body based mic and i think they are a bit ringing from the tube part of the body and i am asking myself what could i use to damp the this.

I see in an aston video that they damp their mic's tube body with what seem to be kind of black bitumen sheets.

 

[Khron]

I would be curious how you plan to damp the body?

i got 3 bm800 body based mic and i think they are a bit ringing from the tube part of the body and i am asking myself what could i use to damp the this.

I see in an aston video that they damp their mic's tube body with what seem to be kind of black bitumen sheets.

A couple years back i bought a sheet (A5-sized or so) of some adhesive-backed rubber, maybe 2mm thick or so, for the purpose of damping mic body tubes. Haven't yet gotten around to actually using it yet, but that might be a cheap-ish option?

 

[Whoops]

I would be curious how you plan to damp the body?

I have some sheets of a material that is not rubber or high density foam but it's somewhere in the middle of both.
I really don't know the same of this material. I can show some photos when I'm doing it.
I will just glue it inside the tube and test it.

I see in an aston video that they damp their mic's tube body with what seem to be kind of black bitumen sheets.

Is that bitumex? I'm pretty sure it will damp it, but bitumex is heavy and I dont even know how to glue it,
I have used inside speaker cabinets made of woor or MDF and I just clamp them to the wood