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R/E/P => R/E/P Archives => Klaus Heyne's Mic Lab => Topic started by: Klaus Heyne on January 09, 2009, 02:45:26 AM

Title: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on January 09, 2009, 02:45:26 AM

I have tested and retested in several set-ups a recent sample of Thiersch's new "Blue Line" (PVC) M7 Neumann capsule copy.

First, this is a wholly-Thiersch-manufactured capsule, i.e. not only does it use Thiersch's diaphragms but also his brass backplate which is patterned after the "Berlin M7", the type that has a particular pattern of concentric rings at the edge of the backplate, and which features other peculiarities.

This effort is a whole step closer to the 'real thing' than his previous attempts, and he is certainly closer than his competitors in achieving the goal to emulate the Neumann M7. Here we have a balanced frequency response in general, with just a tiny bit too little high frequency sheen, reasonably good side-to-side performance, and a pleasant timbre, void of shrillness, lisp, sibilance, or dried up bass.

Considering the trend, I am optimistic that he may succeed in the one area this capsule still lacks- the magic of an M7 to get behind the note, of having a level of resolution and speed of response, from the very high frequencies through the lower mids, that allows the voice or the music come to you, without too much listening effort. A "pearling off" effect, if you will, where the apparatus- the capsule- helps you along.

None too scientific, and probably an annoying description for the pocket protector types among acoustic engineers; but such is the quest for emotional satisfaction through the ear- a decent scientific explanation for the link between hearing, absorbing and the mechanics of getting there is still beyond our reach.

I have some ideas how to maybe overcome what may still be missing in Thiersch's M7 effort. To that end, I have started discussions with him; so let's toast to a successful M7 year!

Title: Re: My New Year's Wish: A Thiersch M7 Breakthrough
Post by: Stephen Andrew Bright on January 09, 2009, 03:52:56 PM

Based on my fondness for the sound of the M7 in my Wunder CM7 GT, I recently ordered Mr. Thiersch's M8 conversion, which is where he takes a stock M8 lollipop capsule and reskins it on both sides and makes it a switchable Cardioid / Fig. 8.

Used M8s can be found at about 1/2 the price of a used M7, and the converted M8 in cardioid sounds like his M7, according to Thiersch.

For me it seemed like an inexpensive way to get the M7 sound, which can then be used on a wide variety of mic bodies.

Stephen

Title: Re: My New Year's Wish: A Thiersch M7 Breakthrough
Post by: Plush on January 09, 2009, 05:03:22 PM

Hello Klaus,

I don't want to be rude, but I can't quite understand your description of the desired sound. Can you state it in a different way. I am wanting to know your thoughts.

How do you suggest the M7 should sound?

Title: Re: My New Year's Wish: A Thiersch M7 Breakthrough
Post by: J.J. Blair on January 09, 2009, 06:34:37 PM

Stephen, I'm skeptical about this M8 conversion claim. The through holes are a completely different beast, and I'm not understanding how you can even mount a diaphragm on the rear.

Title: Re: My New Year's Wish: A Thiersch M7 Breakthrough
Post by: Stephen Andrew Bright on January 09, 2009, 07:33:10 PM

Hi JJ:

You are right -- he uses his own transducer:

http://www.thiersch-mic.de/en/estm_produkte_M8.html

So it is his M7 transducer in an M8 lollipop housing, now switchable from Cardioid / Fig. 8, or Cardioid / Omni.

Stephen

Title: Re: A Thiersch M7 Breakthrough Around The Corner?
Post by: kats on January 15, 2009, 01:48:22 PM

That's great news - keep us posted on developments!

Title: Re: M7 Breakthrough Around The Corner?
Post by: kats on January 18, 2009, 12:27:22 PM

Klaus, as an aside, how do you compare this capsule to a Geffell M7? And while on the subject, how do the Geffell M7's generally compare to Berlin M7's in your experience?

Title: Re: M7 Breakthrough Around The Corner?
Post by: compasspnt on January 18, 2009, 12:36:31 PM

I have a Theirsch M7 here now, comparing directly to a good Berlin M7.

Also have a very good MTG M7 from 1991, but it is mounted in a totally different head, and I probably won't have time to remount for apples to apples comparisons there.

The only conclusion I feel comfortable giving publicly so far is that both the Theirsch and the Berlin totally smoke the (very old) K47 from my U48 for that elusive "sexiness."

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on January 20, 2009, 01:01:16 AM

Terry,
You know that comparing K47 to M7 is an iffy proposition (and you said so in your post.)

To answer the original question, I will give my current ranking of both PVC and Mylar M7 models, based on frequent tests and submissions by both Gefell and Thiersch:

A. PVC-State in 2009

1. Neumann Berlin and Neumann/Gefell, historic stock (when they still work)

2. Microtech Gefell, the ones made until 4-5 years ago

3. Thiersch, current

4. Thiersch, made ca. 1993/4

5. Microtech Gefell, current

B. Mylar/Polyester-State in 2009

1. Microtech Gefell, until 4-5 years ago

2. Tie: Microtech Gefell, current and Thiersch, current

Still my (slightly) favorite M7 capsule, which I use for all of my comparison tests, is a Microtech Gefell M7 POLYESTER! This was a one-off, with truly mind-blowing timbre, fullness, and clarity, Sheryl Crow's 'Soak Up The Sun' was done with a short body U47 with that capsule.

Title: Re: M7 Breakthrough Around The Corner?
Post by: wwittman on January 24, 2009, 12:57:29 AM

Klaus Heyne wrote on Tue, 20 January 2009 01:01

If you want the sound of a true M7, there is only one way today to get it: Buy a Gefell PVC M7 as currently still manufactured (though with some low-end loss)...

so, Klaus, I take it you no longer feel this is true?

I have to say, after evangelising for them for so many years, I recently had some new UMT70s up and was very dissappointed with them.
I have to GUESS this is due to the new run of M7's

first they took out the transformers for no reason, and now this...

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on January 24, 2009, 01:26:19 PM

Yes, I am afraid this old statement of mine is no longer true.

The current Gefell M7 PVC capsules are not up to the excellent standard we used to get from the company. They are uniformly bass-shy, to the point of harshness, and any hint of their historic sex appeal and emotional attractiveness that mainly came from the robust lower mids (let alone frequency balance or side-to-side consistency) is gone.

Yet, I am always optimistic that, as long customers like you will ring their alarm bells, formerly glorious capsule manufacturers get on their feet again, make the changes the public demands, and become contenders once again.

Title: Re: M7 Breakthrough Around The Corner?
Post by: wwittman on January 24, 2009, 08:09:22 PM

I wish, but I doubt Gefell listens to ME. (if they only knew how MANY people I'd bet have bought Gefells over the last 10 years because of my big mouth...)

But you're exactly right.
The new mics had a thinness to them... what I'd call a lack of substance, or solidity.

I could get a mic for 1/4 that price if I was willing to settle for that quality

My UM70s with the transfomer sounds gloriously 3-D in comparison.

Title: Re: M7 Breakthrough Around The Corner?
Post by: kats on February 12, 2009, 02:15:53 PM

So I tried one of these new "blue Line" capsules and compared it to a Mylar skinned M7 copy. My simple 15 minute impression was that it was less "hard" sounding while still maintaining the presence of the Mylar version. It seemed "smoother across the frequencies" but not any less detailed.

It is definitely an improvement IMO over the Mylar copies. But I will have a better overall opinion once I put it through a variety of recording situations over the next month.

Title: Re: M7 Breakthrough Around The Corner?
Post by: seanBfunky on March 16, 2009, 04:17:34 PM

Hi Klaus!

Would you be willing to comment specifically on the sonic difference between the (recent) Thiersch PVC and Thiersch polyester M7 copies?

Thanks!
Sean Broderick

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on March 17, 2009, 01:10:44 AM

Sean,
Your timely inquiry saved me from starting a new thread. Thanks!

I am in the middle of working with Thiersch in identifying the characteristics which make a copy capsule different from the original- both as far as sound goes and the minute, mechanical, build-differences.

This is the fun part (for me) and the crux (for most capsule makers): How do you know when you have it right? Whose ears can you trust when you are the capsule builder? What if several of the "Golden Ears" you lent your new capsule to, in order to decide on what design to go for, contradict each other?

Measurements certainly won't help the builder- we have discussed this ad infinitum here- the minute timbral differences that separate the wannabes from the jackpot are impossible to quantify and, if that was even possible, then to qualify!

There are exceptions, but the rule applies: the capsule builder must rely on a principal person to guide him, through listening tests, in the right direction. The lack of such a relationship in the current capsule making methodology pretty much explains the lack of any break-though towards a new, exciting, musical, frequency balanced, large diaphragm capsule. Hence the same old proven designs are being copied, and not even copied all that well.

As to your concrete question: The situation is quite dynamic with Thiersch at the moment. Since he has started up production of PVC capsules again, the new generation to my ears surpasses his Mylar work; so I'd go for that.

Please also see my rating of currently produced M7 copies, earlier in this thread. I hope to be updating this list some day soon with something that deserves more than just lukewarm endorsement.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Andy Simpson on March 17, 2009, 07:37:48 AM

It would seem that the question of measurement has been discussed 'ad infinitum', and I would agree that the apparently extensive discussion appears to have got nowhere, but not because all avenues have been explored.

I would say that the most critical, fundamental measurements are simply not being made.

If they were, we would not need to be having this conversation.

Andy

Title: Re: M7 Breakthrough Around The Corner?
Post by: Jim Williams on March 17, 2009, 10:57:42 AM

I would tend to agree with this. Research into capsule design has not been fully explored. Part of the reason is the best research labs have no interest in consumer audio. If a M7 was sent up to Cal Tech, it would be subjected to their multi million dollar lab and its top flight equipment. The level of precision done there is the best in the world. Just their laser department would show many of the dynamic reactions of the capsule in high speed.

Since pro audio and its development has been in decline, there are no top level physicists dedicating their talents to microphone design; it's now the purview of audio engineers and EE's.

If there was such interest and top flight lab work was being done, such supposed mysteries would be solved. That would take millions in development costs most don't have to spend on microphones.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on March 17, 2009, 01:33:12 PM

Neither Jim's not Andy's arguments address my point: So you start up that multi-billion dollar test machine at RAND or Cal Tech or MIT. Then - what? Who's going to be the one to interpret the data? And along what criteria? How do you objectively define which M7 is preferable to the professional recordist? The singer? The end consumer?

Let's say, all three user groups agree on which one they like better. Let's even say, the critical feature in the design of THIS particular capsule could be identified among the physical dimensions, tensions, electrical properties,etc. and correlated back to the listening experience. How do you then translate the data output of the sophisticated machinery that displayed the minute timbral variation in the M7 to other capsules, like the K47, the K67, the CK12, the Sony C37....?

Because the desirable outcome of any capsule development is judged primarily (in my case, only) by the ear, rather than derived from any agreed-upon measurement characteristics, it strikes me as impossible to choose any other way than listening to get there.

Title: Re: M7 Breakthrough Around The Corner?
Post by: compasspnt on March 17, 2009, 01:41:24 PM

Give the electric guitarist a choice between an amplifier that "reads out perfect specs," and one that happens to be somewhat "crazy" spec-wise, but sounds big and powerful, and they will always choose the latter.

It is all about the sound at the end of the day.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Unwinder on March 17, 2009, 01:48:37 PM

Your absolutely right Klaus, and it makes complete sense.

The only thing is, where do you find someone with extensive capsule listening experience, and how does one translate these differences down to actual machine work?

Once the machine work and listening criteria are acceptable, then one could presumably trust the measurements in production.

It sounds like Mr. Thiersch and yourself are on the right track to producing an excellent, balanced sounding capsule.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on March 17, 2009, 02:43:21 PM

First,
I believe in the value of making decisions through hearing; listening education needs to be stressed and promoted more in these discussions and in audio engineering and production.

Listening and interpretation of what we hear, and then feeling comfortable in making decisions based upon listening, is not a gift, but a skill. Listening skills can be learned by most, and need to be encouraged.

Second,
I am not in a contractual or commercial relationship with Mr. Thiersch. I just enjoy the fact that he has been open to my input, and that is big, in my book. I sure hope the result will be a better capsule.

Title: Re: M7 Breakthrough Around The Corner?
Post by: J.J. Blair on March 17, 2009, 03:02:25 PM

I can see it now: The Thiersch M7 KHE.

Title: Re: M7 Breakthrough Around The Corner?
Post by: aamicrophones on March 17, 2009, 04:38:14 PM

Hi, I am guessing, that I am wrong here!!! However, I thought the object of audio was to get the frequency response as flat as possible from 20hz to 20,000 hz.

Now the physics of the LDC capsule design always leaves some bumps and valleys in the response and significant differences in the proximity effect. The design criteria one would think is to get this response as flat as possible.

We have just learned to to accept these "flaws" in the response. Some differences are better for certain vocalists and instruments than others as they enhance certain frequencies and harmonics. this is what makes on microphone sound "better" than another in a specific recording situation.

What's interesting is that often a "average" U47 might sound great in SOLO but an "average" C12 will often work better in the track as it often cuts through a bit more.

Again, this is not a given but it is these "Un HiFi" differences that we seem to focus on more than not.

Cheers, Dave
www.aamicrophones.com

Title: Re: M7 Breakthrough Around The Corner?
Post by: Barry Hufker on March 17, 2009, 05:09:07 PM

Dave,

I'll respectfully contend the goal of audio is *not* to get the flattest response between 20Hz and 20 kHz. It is to get the best sound, with "best" being subjective. Some people want an audio "photograph" and therefore want a microphone as neutral as possible. Others want a signal enhancer. In either case, tools are available. It all comes down to "if it sounds good, it is good". Any goal than that may well be a waste of time.

Barry

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on March 17, 2009, 08:46:27 PM

aamicrophones wrote on Tue, 17 March 2009 13:38

Hi, I am guessing, that I am wrong here!!! However, I thought the object of audio was to get the frequency response as flat as possible from 20hz to 20,000 hz.

You might indeed be guessing wrong.

Have you ever seen a frequency response graph of the five most expensive and most desirable microphones ever made for recording music? Radio Shack's top-of-the-line $89.95 Electret condenser will leave each of them in the dust with its ruler-flat response, yet somehow sounds like ... $89.95.

The flattest mics are calibration mics, mostly made by B&K, a few by Microtech Gefell. Why are they rarely used for recording music?

One tiny additional problem with frequency measurements: at what distance from the sound source is the mic positioned, and what's the volume of the test signal? Which manufacturer is adhering to any of many AES protocols in this regard?

Title: Re: M7 Breakthrough Around The Corner?
Post by: mwurfl on March 18, 2009, 02:25:47 AM

My training as a EE led me also for many years to believe that the resultant sound quality of a given audio device could be completely known and predicted by full and accurate charaterization of all the "usual suspect" parameters. Only in the last six or seven years have I begun to truly comprehend how simple-minded and inaccurate this perception is, particularly with respect to microphones. Anymore I liken the process of making fine microphones to that of making a fine violin (or any number of other fine instruments). I have yet to hear of one example where someone has duplicated all the magic of the sound of a Stradivarius by "cloning" all the construction parameters of a violin that can be measured by what metrics we yet know of today. The best are still made "by ear." And so it is, I believe, with microphones.

Klaus, I believe you have it exactly right about the need for making more widespread the knowledge of how to listen, and what to listen for. So here's a question and a challenge: Is there any way you could include a lesson or two about this in your upcoming book, by including a CD/DVD that has high-resolution examples (exaggerated if need be) that one could listen to while reading your narratives? That might be one way to help get more folks on the same page as you when it comes to knowing what to listen for.

Regards,

Mark W

Title: Re: M7 Breakthrough Around The Corner?
Post by: miics on March 18, 2009, 02:35:34 AM

I must agree with Klaus on this one. Over the years i have listened and measured many of the worlds best microphones. What makes them sound so good?

After much deliberation i have come to the conclusion that it is the whole package, the reaction of the capsule to the diaphragm resonance, the capsules reaction to the impdeance conversion/amp circuit, the inductance of the coupling cap, the transformer and even the kinetic control (dampening) of the microphone structure.

What frequency response is best? = Inconclusive, I love at least 16 microphones on this planet and all of them perform very differently!

All i know is that no matter what a mic does on a tef graph, the end result can only be measured by ear.

I am yet to see a Tef/Lindos or Audio precision test set buy a top 40 album.

I currently manufacture 5 different variations of the K47 capsule. Each sounds remarkably different, which one is best? Well i still make all of them because they are different. Sure i have my favourite but that won't necessarily be yours!

Title: Re: M7 Breakthrough Around The Corner?
Post by: Andy Simpson on March 18, 2009, 07:37:14 AM

compasspnt wrote on Tue, 17 March 2009 18:41

Hi Terry,

It is all about the sound, but that is not to say that the AC30 or fender twin would not MEASURE better than a horrible sounding transistor guitar amp.

I would expect these amps to measure a lot better actually.

Andy

Title: Re: M7 Breakthrough Around The Corner?
Post by: Andy Simpson on March 18, 2009, 08:37:14 AM

Jim Williams wrote on Tue, 17 March 2009 15:57

I would tend to agree with this. Research into capsule design has not been fully explored. Part of the reason is the best research labs have no interest in consumer audio.

Hi Jim,

Another part of the reason is that the industry itself has no interest in putting time into proving that the old mics (that people are so fond of) actually measure better than the modern replacements (after all this time).

Quote:

If a M7 was sent up to Cal Tech, it would be subjected to their multi million dollar lab and its top flight equipment. The level of precision done there is the best in the world. Just their laser department would show many of the dynamic reactions of the capsule in high speed.

This would hardly be necessary.

Simple wide-band linearity, polar & self-tuning measurements would probably do the job.

All of which can be done in a standard audio facility.

Quote:

Since pro audio and its development has been in decline, there are no top level physicists dedicating their talents to microphone design;

In general, I agree.

Aside from the hearing-aid industry - who do very good work that some of us pay a great deal of attention to -, what we have is mostly marketing.

As far I'm concerned, the 'mysteries' are all quite measureable & applicable (as can be seen from the writing on my website).

However, I'm not interested in reproducing the old capsules & their limitations, as it is a better use of time to simply improve on them.

Andy

Title: Re: M7 Breakthrough Around The Corner?
Post by: Jim Williams on March 18, 2009, 11:34:04 AM

compasspnt wrote on Tue, 17 March 2009 10:41

Bad analogy, the amp is an extension of the instrument, in this case, an electric guitar. Sonic choices for instruments are always selected on a subjective consideration.

However, understanding the reactions of a mic capsule is not the same as a guitar amp which is intentionally designed with non-linearities in mind.

I fail to see how understanding how and why a capsule has it's characteristics is a bad thing. If as Klaus suggests that this is the domain of "tuners" and alchemists, there is no hope other than to trust a manufacturer and not question any of the efforts made to get there. I just don't have that much faith in alchemy.

Title: Re: M7 Breakthrough Around The Corner?
Post by: marcel on March 18, 2009, 11:57:16 AM

If somebody suddenly pulled back the curtain to reveal the wizard, the days of selling a replica of a 50 year old mic for $10k may be over.

I tend to agree, although it's a pretty cynical perspective, that many in the industry are happy with the lack of 'modern science' in this.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Unwinder on March 18, 2009, 02:54:26 PM

- "Bad analogy, the amp is an extension of the instrument, in this case, an electric guitar. Sonic choices for instruments are always selected on a subjective consideration."

Who cares if it's a bad analogy or not? It's an easy to understand point.

- "I fail to see how understanding how and why a capsule has it's characteristics is a bad thing. If as Klaus suggests that this is the domain of "tuners" and alchemists, there is no hope other than to trust a manufacturer and not question any of the efforts made to get there. I just don't have that much faith in alchemy."

I don't recall Klaus ever implying this or using those words.

"There are exceptions, but the rule applies: the capsule builder must rely on a principal person to 'guide him, through listening tests, in the right direction.' The lack of such a relationship in the current capsule making methodology pretty much explains the lack of any break-though towards a new, exciting, musical, frequency balanced, large diaphragm capsule."

Klaus suggested that critical listeners need to work together with engineers to improve the current state of capsule sound.

He did not imply that ANYTHING was "In the domain of the alchemists".

Sheesh. Peace out.

Let's please keep the conversation civil and without getting personal. Thanks! K.H.

Title: Re: M7 Breakthrough Around The Corner?
Post by: J.J. Blair on March 18, 2009, 06:43:23 PM

And just to emphasize that point, I think the failure of some of the old mic companies and a couple of the newer ones is that they are not working in concert with certain end user engineers, who really know how to give feedback. I know that there are some fantastic designers at some of these old companies, but I can't see how the ears of some people might have been used, upon hearing any of the mics they've offered in the last fifteen years. There are a couple of companies who have made improvements due to my unsolicited, and unwelcomed feedback. Imagine if when designing these mics, they actually sent prototypes to working engineers, who know what the great mics sound like, and got feedback. I'm having a really hard time believing that they are doing that.

A friend of mine is the main guide for Tree Tops Lodge in Kenya. Mercedes flew in three prot0ypes of the ML320, when they were developing that. They gave them to my friend and said, "break them." My friend and his cohorts proceeded to drive them into the ground, and then Mercedes came back, analyzed what went wrong, and improved their designs.

That's the type of teutonic attempt at perfection I expect from these mic companies, but I guess we won't see again.

Title: Re: M7 Breakthrough Around The Corner?
Post by: jrmintz on March 18, 2009, 08:06:03 PM

I think the unfortunate fact is that hands-on, full-time, experienced professional users are a miniscule part of the market. Aside from a few folks like David Bock, we're just largely irrelevant to the marketing processes of microphone companies.

Title: Re: M7 Breakthrough Around The Corner?
Post by: wwittman on March 19, 2009, 06:09:50 PM

I suspect that's a good part of the problem.

They probably ARE taking "advice" as to what Guitar Centre or Sweetwater "wants" from them.

Title: What sells converters must sell microphones, right? Wrong.
Post by: Andy Simpson on March 20, 2009, 08:25:43 AM

I think that a great part of the problem is that the 'digital revolution' has been leading the microphone industry into trouble it didn't expect.
If we look particularly at the post-digital development of the microphone we see quite a clear progression towards extension of bandwidth into the ultrasonic range.
The problem is that the motivation & justification for extended converter bandwidth is not applicable to the microphone.

What we have is a seriously misled industry, heavily invested in the idea of extended bandwidth.
This heavily invested industry - invested in marketing & development - does not want to consider the obvious fact that ultrasonic bandwidth is clearly not the priority of the ear.

In other words, the well-known microphone companies who have committed all their marketing & development resources to increasing microphone bandwidth on the back of the rapidly moving digital market are extremely reluctant to consider that the fundamental linearity they have traded for wide-bandwidth is actually more important to the ear.

Despite the weight of feedback from engineers who still use the old mics, having so much invested they dare not investigate the old low-bandwidth microphones for fear of what they may find.
To do so would be to contradict themselves, which would mean undermining decades of marketing weight and a further loss of confidence in the market.

Andy

Title: Re: What sells converters must sell microphones, right? Wrong.
Post by: compasspnt on March 20, 2009, 09:21:34 AM

...And thereby having some "splaining" to do to their venture capital group/corporate owners.

Title: Re: M7 Breakthrough Around The Corner?
Post by: jrmintz on March 20, 2009, 09:41:47 AM

I think we can probably agree that there haven't been many real improvements in sound "quality" in the last forty years or so. Storage media, miniaturization, interfaces, lowering of price point - that's where most of the change has happened. In my view the recording industry, as viewed by most manufacturers, has become almost entirely semi-professional. That's the direct result of the "improvements" made to gear in the recent past. The mic companies are looking at a very small professional recording market that's largely saturated with product they made thirty to fifty years ago. I'd imagine they're fighting to differentiate themselves from each other in the low- to mid-priced part of the market, where the mass sales are.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Barry Hufker on March 20, 2009, 11:29:15 AM

It was made clear to me today that audio may be singular in this regard when it comes to technology. A email list of used video gear for sale showed me that used video equipment has no nostalgia or benefit other than being cheaper than new. No one I'm aware of is hanging on to their 50s, 60s, 70s, 80s, 90s cameras or videotape decks yet we in audio happily and readily claim gear from the past.

Title: Re: What sells converters must sell microphones, right? Wrong.
Post by: Klaus Heyne on March 20, 2009, 02:05:52 PM

Andy Simpson wrote on Fri, 20 March 2009 05:25

If we look particularly at the post-digital development of the microphone we see quite a clear progression towards extension of bandwidth into the ultrasonic range.

Can you cite some published specs to that end? I was not aware that the frequency range of a mic which is defined not by the mic's processor but by extremely band-limited ld capsules, like for example Neumann's K47 or K870, could be extended somehow into the ultrasonic range?

Title: Re: What sells converters must sell microphones, right? Wrong.
Post by: Barry Hufker on March 20, 2009, 02:59:54 PM

There are examples by DPA, Sennheiser and Sanken. Schoeps also makes a claim about ultrasonics, but the most dramatic example is linked here, the Sanken CO-100K:

http://www.sanken-mic.com/en/product/product.cfm/3.1000400

Here is Sennheiser's claim: "The frequency response extends to 50 kHz, thus improving the resolution for complex acoustic details." You can find the microphone here:

http://www.sennheiserusa.com/newsite/productdetail.asp?trans id=502431

I leave it to others to look up DPA and Schoeps. I don't know of any effort by Neumann or AKG which attempts to capture the ultrasonic.

Barry

Title: Re: M7 Breakthrough Around The Corner?
Post by: wwittman on March 20, 2009, 06:20:06 PM

I still think it's less engineering (into "ultrasonics") type choices, and more about marketing to the semi-pro (which is a MUCH bigger share)

I wonder how much Shure makes on each KSM32 versus what Brauner makes on each VMA. Tthen multiply that by the numbers sold...

Title: Re: What sells converters must sell microphones, right? Wrong.
Post by: Andy Simpson on March 21, 2009, 06:27:03 AM

Klaus Heyne wrote on Fri, 20 March 2009 19:05

Andy Simpson wrote on Fri, 20 March 2009 05:25

If we look particularly at the post-digital development of the microphone we see quite a clear progression towards extension of bandwidth into the ultrasonic range.

Hi Klaus,

That's rather the point I was trying to make.

Basically we can't raise the bandwidth of the LDC without trading either noise-floor or linearity (or both) for it.

To measure these old mics is to show how much fundamental linearity has been traded for the useless (even detrimental) bandwidth & noise-floor performance of the modern versions.

Andy

Title: Re: What sells converters must sell microphones, right? Wrong.
Post by: Andy Simpson on March 21, 2009, 06:52:48 AM

Barry Hufker wrote on Fri, 20 March 2009 19:59

Hi Barry,

This is a great example of the trade-off.

Looking at the frequency response (15dB up at 50kHz) and the quoted distortion spec (<1% @125dB SPL), I would expect really really high levels of distortion in the ultrasonic range where sensitivity peaks.

In this case, the worst thing that can happen is that there actually is ultrasonic acoustic energy, because it will simply 'fold down' to the audible range in the form of intermodulation distortion.

Andy

Title: Re: M7 Breakthrough Around The Corner?
Post by: MDM, on March 21, 2009, 11:15:23 AM

the ultrasonic thing is more of a niche.

most mics don't concentrate on that, altough some do.

I think the dumbest technical issue to ruin it for pro users is the concept of euphonic distortion etc.

like having a tube connected to the capsule at low voltages and then driving the output with a chip or something silly like that.

Title: Re: M7 Breakthrough Around The Corner?
Post by: aamicrophones on March 21, 2009, 03:42:35 PM

Hi Klaus, how has the Thiersch-manufactured PVC capsule overcome the tendency of the softening agent or modifier which creates application failure in pressure sensitive films where the plasticisers are found to migrate into the adhesive system causing the film to delaminate from the substrate surface and cause the "crinkling effect"?

My sense is the U47 with its large wirewound filament dropping resistor that ran very hot was a contributer to the early aging of the M7 capsule and the stress fractures in the PVC film were the result of the temperature changes between the microphone being on then cooling down when it was turned off.

Are the PVC formulations better now and the newer tube microphone generate less heat because they don't have the large filament dropping resistor that generated more heat than even the VF14 tube.

Cheers, Dave

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on March 21, 2009, 05:52:33 PM

Dave, I am not privy to Thiersch's PVC formulations. That's his proprietary domain.

It is true- PVC does dry up with time; yet, I am not aware that there are PVC formulations that have the mechanical properties of the traditional formula, but avoid the deterioration over time.

The devil is in the detail with PVC: one manufacturer of PVC capsules no longer has access to the original, post-WWII powder. When that was replaced, with a current formula, the capsules no longer sounded the same.

Title: Re: M7 Breakthrough Around The Corner?
Post by: aamicrophones on March 21, 2009, 06:40:23 PM

Hi Klaus, I hypothesize that the PVC was more likely to "age" quicker in the U47 which ran quite hot as there would be a greater difference in the temperature between when it had been running for a few hours and then turned off after the session. It is my novice understanding of PVC film that these temperature difference age it more quickly.

Cheers, Dave

Title: Re: What sells converters must sell microphones, right? Wrong.
Post by: Jim Williams on March 22, 2009, 12:44:50 PM

Andy Simpson wrote on Sat, 21 March 2009 03:52

Barry Hufker wrote on Fri, 20 March 2009 19:59

Then you can add to the stew the effects of hf DC converter oscillators that are observed under a scope. Many popular mics show large amounts of HF oscillator leakage into the audio path, looking much like record bias on magnetic tape. I know of no research into the possible negative effects of this type of intermodulation to the audio path but since so many makers use this topology, it would be a great AES paper if AES was interested in analog electronics enough to publish it.

Title: Re: M7 Breakthrough Around The Corner?
Post by: J.J. Blair on March 22, 2009, 02:26:11 PM

aamicrophones wrote on Sat, 21 March 2009 15:40

You should see the M7s that were in my M49s, then. Just as crappy as any I've seen in a U47.

Title: Re: M7 Breakthrough Around The Corner?
Post by: David@The-Tone-Room on March 22, 2009, 06:38:10 PM

Klaus;

I wonder, in addition to listing your favorite M7 replacement capsules, if you could provide some information as to actually finding and purchasing one of those capsules. (For example, how would I go about identifying and purchasing a Microtech Gefell M7 from 4 or 5 years ago? Or, how would I find and identify a Berlin M7?)

If it's not appropriate to provide vendor details in the forum itself, could you perhaps by email?

Many thanks!

David K

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on March 22, 2009, 08:10:35 PM

Microtech Gefell PVC M7 are easily recognized by two unique features.

One, the center screw has a 1.0mm thread, rather than the 1.2 mm thread which was and is standard on all Neumann capsule lead-out screws. Though you cannot see the thread when the screw is fastened, its smaller head size gives it away. (someone else can supply some nice JPGs to illustrate!)

Second, Gefell used, and still uses, Neumann's M7's pre-World War II ridge configuration:

Looking at the rim of the capsule, you will recognize several concentric ridges and troughs that are visible under the stretched diaphragm, towards the edge of the capsule, where the diaphragm is glued to the backplate. Neumann used three ridges, Gefell two.

However, after the war, Neumann used many different configurations as to width of ridges and troughs, which allow for M7 period classification, yet there were always three ridges, until the introduction of the K47, which had only one.

When discussing visual identifiers, please keep in mind that Gefell's backplate configuration for its current-day Gefell M7 with Mylar

Title: Re: M7 Breakthrough Around The Corner?
Post by: J.J. Blair on April 13, 2009, 02:59:42 PM

Klaus, I just wanted to chime in and say that I got a chance to test one of the Thiersch made M7s the weekend. The blue line is the PVC?

It was fantastic! I don't know how to compare it to a Berlin M7 in proper condition, but I have a Gefell M7 that is less than ten years old, and a recently reskinned (by Gefell) Berlin M7, and I referred it to both. The high end was gorgeous and I preferred the over all timbre. I also compared it to a cream K47 that I have here, and the mid range was smoother. The K47 was piercing, in comparison. I might even replace the K47 with the M7, after further testing, I liked it so much. I need to do some tests on an upright bass first to see what the low end is like.

If you're telling me that there's another 5% better they can still go with these, I'm terribly excited to hear what that will sound like. I would totally recommend anybody consider using these as a replacement in their U47.

I'll try the M49 tests later!

Title: Re: M7 Breakthrough Around The Corner?
Post by: delcosmos on April 13, 2009, 03:10:44 PM

This is really good news JJ. I hope it passes the upright bass test too. I have a beautiful U47 that really needs a new capsule. I don't want a re-skin.

Thanks for the report.

delcosmos.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on April 13, 2009, 06:14:02 PM

J.J. Blair wrote on Mon, 13 April 2009 11:59

...I don't know how to compare it to a Berlin M7 in proper condition, but I have a Gefell M7 that is less than ten years old, and a recently reskinned (by Gefell) Berlin M7, and I referred it to both.

Agreed, compared to the recent Gefell PVC output, the Thiersch M7-PVC wins, and wins in a manner fairy obvious to even a casual listener.

But that comparison (as sad as what it says about Microtech Gefell's current M7-PVC quality) is not relevant for anyone who wishes to replace an original capsule in his precious U47/U48 or M49. That standard (and my expectations) is higher: The capsule has to deliver magic.

You may be right we are still a few (but vital!) percentages short of that magic with Thiersch's new PVC capsules.

Title: Re: M7 Breakthrough Around The Corner?
Post by: MDM, on April 14, 2009, 06:37:00 AM

hmm....

think I'll get thiersch to re-skin, the re-skin he did in mylar years ago on a capsule I have.

JJ

do you find that the top-end is a bit 'gummy' ?

Title: Re: M7 Breakthrough Around The Corner?
Post by: J.J. Blair on April 14, 2009, 11:09:33 AM

Max, no. Clear as a bell.

Title: Re: M7 Breakthrough Around The Corner?
Post by: synthetic on October 18, 2009, 10:32:40 PM

Klaus Heyne wrote on Mon, 13 April 2009 15:14

...compared to the recent Gefell PVC output, the Thiersch M7-PVC wins, and wins in a manner fairly obvious to even a casual listener.

But that comparison (as sad as what it says about Microtech Gefell's current M7-PVC quality) is not relevant for anyone who wishes to replace an original capsule in his precious U47/U48 or M49. That standard (and my expectations) is higher: The capsule has to deliver magic.

You may be right we are still a few (but vital!) percentages short of that magic with Thiersch's new PVC capsules.

Are new production Gefells to be avoided? A few years ago that was one of your top picks.

Jeff Laity

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on October 19, 2009, 01:43:06 PM

If with "Production Gefells" you mean MG microphones with PVC M7 capsules (there are only two models in the company's current line-up, if I calculate correctly), it is hard to imagine how a mic can sound frequency balanced, emotionally attractive and musical if its capsule is so harsh and constricted in the mids as these capsules now are.

It has been widely reported by those in the know that MG finally ran out of the original PVC material they were using for decades a few years ago (in addition to the retirement of the original diaphragm specialist.)

I can tell you this with confidence: MG's PVC capsules made until about 5-10 years ago were outstanding, and fully compatible with the quality expected of an original Neumann Berlin M7 from the 1950s. Quite a few of them had the 'magic'.

On the other hand, MG's polyester (Mylar) M7 are among the best one can find these days.

Title: Re: M7 Breakthrough Around The Corner?
Post by: synthetic on October 19, 2009, 02:32:28 PM

I was looking at a UMT 70S. Their website doesn't specify if the capsule is PVC or Mylar, "The pressure gradient transducer is a dual capacitor design using a single brass back plate and two large diameter gold plated plastic membranes."

Title: Re: M7 Breakthrough Around The Corner?
Post by: Mike Cleaver on October 19, 2009, 11:46:42 PM

Over in the "Whatever works" forum, Terry Manning is revealing that the LUCAS CS-4 will have a "new" M7 Capsule.
Here's the relevant post:

"The capsule of course is completely different.

It is a German newly built PVC M7, available for now in a new mic only in the CS-4."

With the success of the CS-1, I'm anxiously awaiting to see if what they are developing is the answer to the "M7 unobtanium problem."

Title: Re: M7 Breakthrough Around The Corner?
Post by: compasspnt on October 20, 2009, 12:36:50 AM

Hi Mike,

And a later post states...

"Dipl.Ing. Siegfried Thiersch will be making the PVC M7 for the CS-4."

Title: Re: M7 Breakthrough Around The Corner?
Post by: synthetic on October 20, 2009, 12:15:48 PM

It appears that the UMT70S is one of the PVC models.

Title: Re: M7 Breakthrough Around The Corner?
Post by: recordinghacks on October 27, 2009, 02:03:04 PM

Klaus Heyne wrote on Mon, 19 October 2009 10:43

If with "Production Gefells" you mean MG microphones with PVC M7 capsules (there are only two models in the company's current line-up, if I calculate correctly)...

Klaus, I gulped when I read that, because my mic database shows many PVC-membrane capsules from Gefell:
http://recordinghacks.com/microphones/tag/pvc

It is true that the MG website does not promote the company's use of PVC diaphragms, except in the 'M 990 art' and 'M 930 art', both of which use an M930-style capsule with PVC diaphragm.

Nonetheless, I was told by a Microtech-Gefell sales engineer last year, and again today (in response to a request for confirmation), that all the M7-capsule mics in Gefell's current product lineup still use PVC diaphragms.

I welcome corrections if anyone knows differently.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Klaus Heyne on October 27, 2009, 02:51:59 PM

That is not correct. Most MG mics with an M7-style backplate use Mylar/Polyester diaphragms.

When I get a chance, I will sift through the current model line-up and point out which mics, aside of the 92.1s still use a PVC membraned capsule.

Title: Re: M7 Breakthrough Around The Corner?
Post by: J.J. Blair on October 27, 2009, 05:38:45 PM

I'd like to point out that I have an early 1959 U48 here with a Berlin M7. I just had Thiersch reskin it in PVC, and it is excellent. It matches up nicely wit the M7 which was completely his.

I still find it preferable to any of my K47s, at least in a U47/48, and I prefer it to the Gefell reskinned Berlin M7 which I had. I found the Gefell PVC reskin to be duller on the top end.

Title: Re: M7 Breakthrough Around The Corner?
Post by: maarvold on October 31, 2009, 07:44:56 PM

J.J.,

Largely due to your early enthusiasm about the Thiersch Blue Line (PVC), I bought a PVC-skinned STW 7 (his current production version of the M7). At my request, Dave Pearlman used it to replace my Neumann K47 in my Pearlman TM-1 (EF14 & Dave's "Historically Accurate" BV8 transformer--as I believe he calls it). I liked it so much that I immediately had Dave build me another mic exactly the same way. These mics may not be exactly U47's, but they are close enough for me that I would always use them first because they are quite close to what I want in a U47 and--if I have to punch in a line at a different studio--I have the repeatability of being able to use exactly the same mic, since I own it. The Theirsch PVC capsules are very nice, imo.

Title: Re: M7 Breakthrough Around The Corner?
Post by: Sinocelt on September 10, 2010, 02:08:05 AM

Klaus Heyne wrote on Tue, 20 January 2009 00:01

I will give my current ranking of both PVC and Mylar M7 models, based on frequent tests and submissions by both Gefell and Thiersch:

A. PVC-State in 2009

1. Neumann Berlin and Neumann/Gefell, historic stock (when they still work)

2. Microtech Gefell, the ones made until 4-5 years ago

3. Thiersch, current

4. Thiersch, made ca. 1993/4

5. Microtech Gefell, current

B. Mylar/Polyester-State in 2009

1. Microtech Gefell, until 4-5 years ago

2. Tie: Microtech Gefell, current and Thiersch, current

Still my (slightly) favorite M7 capsule, which I use for all of my comparison tests, is a Microtech Gefell M7 POLYESTER! This was a one-off, with truly mind-blowing timbre, fullness, and clarity, Sheryl Crow's 'Soak Up The Sun' was done with a short body U47 with that capsule.

Any update for 2010?