Warm Audio WA-67 - Teardown

[Whoops]

Received a Warm Audio WA-67 microphone for repair.
The capsule was loose inside the head-basket



Upon inspection,
the capsule mount, which is made of some cheap and not flexible plastic, broke near the screw hole thus leaving the capsule loose inside the head-basket.
Or the center screw was overtightened at the factory or the plastic mount had already some production defect.
Anyway the type of plastic used is really easy to crack/break, so it can't be over-tighten,
I'm pretty sure the same thing will happen to other WA-67 microphones



The gold sputtering in both diaphragms was also damaged from the free rides, one side is worse than the other

 

[Whoops]

The microphone is built using some good quality components:
- a Lundhal LL1965B output transformer and Electro Harmonix EF86EH tube





Resistors are 1% metal film and capacitors are all Polysterene or Wima, except the output one which is a Solen capacitor made in Taiwan (not in France like the manual says).

 

[Whoops]

CAPSULE

This is what Warm Audio says in their website and the mics manual about the capsule used:

"we went to great lengths to recreate the capsule from the original ’67, making sure that ours performs the same way, has the same frequency response and contributes to the same chewy character as the original. That meant not only ensuring that the hole pattern was identical, but we also made sure to craft the entire assembly out of brass (including the mounting rings) just like the original design. It takes more time and it’s more expensive than using multiple types of material, but we felt that it was critical to go the extra mile on this microphone."

About the mounting rings being made of brass "like the original design" I'm not really sure about that statement as Neumann produces these capsules since 1960, and only in the first 4 years the K67 capsule had brass rings, so in all original Neumann capsules ever made there's 4 years of brass rings and 57 years of plastic rings... So what should be considered original?

As for the hole pattern the capsule they've put in this mic doesn't seem to have the common K67 hole pattern, it's a bit strange and different and also different than the photo of the capsule Warm Audio has in their website.

Here is the photo from Warm Audio website, showing a capsule that seems to have the standard K67 hole pattern, the ring has recessed screws:



And here is the hole pattern of the capsule that came with the mic, notice also this one doesn't have recessed screws:





It seems there's less holes in the backplates and it's also a strange pattern that I haven't seen before,
so why bragging with "the hole pattern was identical (...) just like the original design (...) but we felt that it was critical to go the extra mile on this microphone". More bullshit from Warm Audio?




I don't know who makes this capsule but there's some red separators between the rings and the backplates

 

[Whoops]

How does it sound?

After I 3D printed a new mount for the capsule and put everything back together I did some recording tests.
The microphone sounds really Good, I have only positive things to say about the sound. I have to use it in recording sessions and do also some tests with original Neumann U67, but at at first glance the sound is great.

I think that they decided to use Polystyrene capacitors after the PCB layout was made because those capacitors are just crumbled on top of each other, well it works but aesthetically the pcb layout could be better for those bigger caps. It's not elegant for sure



The PCB seems a bit cheap, as the copper traces seem to have no protection on top of the copper,
I find that a little bit strange it resembles more a home etched PCB.
Although it's a double sided PCB, I noticed that the components are only soldered on the back side, with no solder reaching the top side.
So I will solder them on the top side as well as I'm sure that although the mic is working well at the moment, that soldering on the top side will help prevent some future failures for sure.

 

[Whoops]

Overall I think this is a good sounding microphone,
made with good components (capacitors, resistors, transformer, tube) the cable is Gotham GAC7 although the XLR connectors are cheap chinese Neutrik knock offs.
I'm not sure on the capsule as the hole pattern is different than standard K67 capsules... Maybe someone can chime in on this.

The capsule mount I'm sure will break in other mics also, and I would resolder all components in both sides of the pcb and probably solder thin all the pcb traces as the traces seem unprotected and might develop corrosion over time, other option is to spray the pcb with protective pcb lacquer.

The body is not well dampened and there's ugly ringing when you tap on it, this is something that doesn't happen in a U67, when you tap on a U67 there's a low end thump sound but no ringing at all, this is a problem common in Chinese mic bodies.

It's less than 1/5 of the price of a Neumann U67 so they had to cut costs for sure, but overall I think it can be a good buy if the issues I talked are addressed.

 

[andYz00m]

Nice teardown and analysis!

 

[pucho812]

We had a warm 67 in and did some comparisons with our vintage u67's. It was obvious as to which was which in an unlabeled audio listen test.

 

[andYz00m]

I finally bought the bullet and purchased a 67 reissue after doing a ton of testing with clones and boutique “67 style” mics. They all can sound great but if the real thing is what you’re after… then nothing else will do.

I bet this write up will help some warm users avoid issues though.

 

[Whoops]

I finally bought the bullet and purchased a 67 reissue after doing a ton of testing with clones and boutique “67 style” mics. They all can sound great but if the real thing is what you’re after… then nothing else will do.

Nothing against what you guys wrote,
but I'm pretty sure if your Neumann "67 reissue" was compared to pucho812 "vintage u67's" it would be obvious as to which was which in an unlabeled audio listen test...

I had 2x vintage Neumann U67's in the studio I worked for many years, both sounded great and both were well serviced, in listening comparisons between both of them it was obvious as to which was which.

All components age over time and they age differently, some components age more than others, like capsules and electrolytic capacitors. 5 Vintage mics of the same model will sound slightly different from eachoter. And a new made mic of the same model and brand will not sound the same as a mic made 50 years ago being it a Neumann or a Warm Audio.

These circuits are so simple, so well known, so explored and talked about that there is no reason for not being able to do it perfectly for 1/5 of the price that overpriced Neumann sells it.
There's no secret ingredient here or any hidden magic, it's just a mic with a simple circuit, simple components and uses the most LDC produced capsule in the world for the last 60 years

my 2 cents...

 

[C12VR]

The new capsule looks like 3uaudio's "flat" k67, which is weird if the mic is designed with the original NFB pathway of the original. It has different wires, which may mean it was produced by another facility, but given that the r1 wa87 had a 3u k87 it is not out of the question.
I wonder why they chose such a high value cap at that output--seems like at that point you might as well do away with the thing in the first place.

 

[Whoops]

The new capsule looks like 3uaudio's "flat" k67, which is weird if the mic is designed with the original NFB pathway of the original.

EDITDED - 25/05/2022

The capsule is an AYM ME-140 capsule.
The backplate is modified with less holes than a K67 to achieve a "flatter" frequency response, less High end boost from the capsule.

3U Audio also produces a similar capsule with modified backplate with less holes, and other mics from Warm Audio use 3U Audio capsules like the WA-47, but that's not the case with the WA-67 it uses an AYM ME-140 capsule and not a 3U Audio capsule.

The WA-67 circuit has exactly the same high end reduction circuit as the original U67, so without the presence bump from the capsule we can expect the WA-67 to sound Darker than a U67.

______________________________________________________________________

I don't know about the 3uaudio's "flat" k67 capsule, can you please let me know more about it?
Is it the reason there's less holes in the backplates and a uncommon pattern, to make it more flat without the presence bump of the K67 capsules

I haven't compared the microphone circuit against the original U67 schematic but I will do in the next days and see if Warm is using a copy of the original circuit or if they modified it somehow.

At the moment I was led to believe the circuit is exactly the same as the original,
nothing in Warm Audio description tells they modified the circuit so I will check and confirm that.

 

[mrgrooves666]

Yes it does at least look like 3U's modified backplate design, wouldn't know for sure for the rest of the capsule assembly.I think this mic must be missing usual demphasis part in the circuit, hence why they are "doing" it at the capsule level with 3U's modified backplates.. Some savings on extra components perhaps, the cost of capsule must be the same anyway...?

 

[C12VR]

I remember reading the specs for the transformer and the tertiary winding was there; would be weird if they custom ordered a tranny just to waste its most distinctive feature.

 

[Whoops]

I remember reading the specs for the transformer and the tertiary winding was there; would be weird if they custom ordered a tranny just to waste its most distinctive feature.

I would think the same.

Could you please tell more about 3U's modified backplate design?

Thank you

 

[C12VR]

essentially it is optimized for a flatter response in the high treble around 8-12k. kingkorg once said something about the hf response flattening out in proportion to the reduction of blind holes in the backplate. I am no expert on capsule design or physics, so this is the best I can offer.

 

[Tim Campbell]

essentially it is optimized for a flatter response in the high treble around 8-12k. kingkorg once said something about the hf response flattening out in proportion to the reduction of blind holes in the backplate. I am no expert on capsule design or physics, so this is the best I can offer.

Yes this is that backplate design. The funny thing is these capsules have lower output so are a bit noisier and damping the high end could be done more efficiently other ways or at least more elegantly with backplate design. I've always thought that this design is a little clumsy.

 

[k brown]

The microphone is built using some good quality components:
- a Lundhal LL1965B output transformer and Electro Harmonix EF86EH tube

View attachment 88188

View attachment 88189

Resistors are 1% metal film and capacitors are all Polysterene or Wima, except the output one which Warm Audio brags in their website and in the mic's manual about being "a large output capacitor from Solen, France" but in this mic was actually a MET capacitor made in Taiwan. I'm pretty sure this MET capacitor is good, but there was no need to brag about a lie, just marketing bullshit talk from Warm Audio

View attachment 88190

That's the Solen logo on the 'MET' cap isn't it? Maybe made in Taiwan for Solen?

 

[Whoops]

That's the Solen logo on the 'MET' cap isn't it? Maybe made in Taiwan for Solen?

You are correct, I didn't see the "Solen" logo, I didnt know who Solen was to be honest.
I've only seen "MET" and "Made in Taiwan" after reading the manual where they brag about a French capacitor in the output.
But I will edit my post.

here's what they say in the manual:

"THE CAPACITORS
The WA-67 proudly uses high-bandwidth polystyrene capacitors, as well as boutique capacitors from Wima throughout, and an imported Solen French capacitor on its output."

 

[Whoops]

I do think it's crappy of them to use it in a mic where they advertise getting the capsule perfect.

Yes it is,
and thats one thing that annoys me with this type of marketing bullshit from some companies,
I don't think less of them because they are selling a cheaper product made in China, I think thats cool and as I already said I think Neumann is overpriced and there's ways of doing it very well for much less than Neumann charges.
But all this bragging marketing communication I think it's really ridiculous.

Michael Jolly had the same type of communication, the horrible people at Mic and Mod have it also.

Advanced Audio and 3U Audio make great affordable microphones and they don't have it fortunately.

It also means they have to change the feedback filter for deemphasis which is going to result in a noticeably different frequency response

For sure that will change the frequency response and make it somewhat a different microphone.
I will have to check if the circuit is true to the original or if there's changes.
In case they didn't change the circuit so the De-Emphasis is still there this could be a production error,
I wouldn't be surprised if the factory assembling this for Warm Audio run out of normal K67 capsules, and just fit the next K67 they had in stock....It's a possibility,

I will check the circuit and also contact Warm Audio and confront them with their statements about the capsule and the photos of this one.

 

[kingkorg]

Neumann uses similar approach with their TLM103 capsule, reduced count and altered size of the holes.

Yes it is 3U audios capsule. Like most other WA models.