Dynamic mics - why so difficult to reproduce?

[soapfoot]

The NS10 driver works especially well for that purpose due to its F(s) of (IIRC) 58 Hz

When it’s excited, it basically resonates at that frequency, which some people find flattering for kick drum in certain applications

It’s not neutrally “capturing” the acoustic drum so much as supplementing it with a largely-undamped low frequency resonance

A different speaker will resonate at a different frequency (its own), which may or may not be as helpful

You’d have to look up that particular driver’s T/S parameters to know what’s actually going on

 

[samic]

I worked for a company that wanted to make a dynamic microphone for the mass market
we bought dozens and dozens of dynamic capsules on the shelf to get closer to an SM7, and it was a huge fail, impossible to have a good capsule in China! if you don't put 150k€ of research and development for the design and build your own winding machine and membrane manufacturing it's over you will never have quality,
in my opinion it is 10x complicated to manufacture than a K67 static capacitor capsule!

 

[engineerkyle]

Sylvia Massy (sic) "American record producer, mixer, and engineer" (says Wikipedia) sometimes/often uses a big speaker (as in guitar amp speaker) as a bass microphone to pick up guitar amp speakers, as described in a video interview last year with 'SoundOnSound' magazine.

This is both true and old news. Legend has it the first use of a subkick was for “rain” by the Beatles.

 

[Dave Obergoenner]

I've worked in both radio and recording studios for most of my life.

I have a lot of condenser mics in my home studio. Some fairly expensive, and some not so much, but modified such that they sound like the expensive ones. What do I use for my voice-over work?...One of my two 40+ year old Shure SM-5B dynamics. Before that, Heil PR-40 dynamics, which sound pretty close.

(Sorry Shure...The SM-7 (I have plenty of them) do not sound like my SM-5B's...even though you kept telling us that they did) I used to buy-up all the nasty, trashed SM-5B mics I could find back in the 1990s, and then restore/refurbish them for use at all the News/Talk stations I engineered. Lots of radio stations were very happy to trade me a nasty SM-5B for a brand new RE-20, or Heil PR-40.

A local NPR FM station I work for has plenty of condenser mics. What do they use for on-air and production?... Heil PR-30 mics, and a few EV RE-20's...mostly for guests who don't know how to use a microphone. They need to match the sound of the high-dollar condenser mics used by NPR (I think mostly U87s). The PR-30's can come very very close (with hardly any EQ), for about 1/10th the cost, and don't pick up all the room noise. Lots of times I can't tell on the air if I'm listening to something from NPR, or something done locally.

I believe there's certainly a place for condenser mics, but there are also a LOT of applications where a dynamic is a MUCH better choice. I'd like to see more new options in dynamics. Shure could probably reissue a true SM-5B pretty easily, an make a killing! Not that much different from a 57 inside...although there's a little more to it than that. For many people who are old enough to have worked with them, that's still the ultimate voice-over mic.

Dave O.

 

[MicMaven]

, it's understandable manufacturers are not very enthousisatic.

Ah ... yes. If you speak this aloud, you realize this IS the correct spelling, after a wee dram or two of good Scotch or Bourbon !!

(Anonymous)



[Just poking a little fun. Move along Johnny, nothing to see here ... ]

 

[abbey road d enfer]

Ah ... yes. If you speak this aloud, you realize this IS the correct spelling, after a wee dram or two of good Scotch or Bourbon !!

I toatlly argee wiht yuo.

 

[abbey road d enfer]

I believe there's certainly a place for condenser mics, but there are also a LOT of applications where a dynamic is a MUCH better choice.

I agree with you, however I think things are not as clear cut as it seems. In particular, the reputation of dynamic mics to pick up less room and be less feedback prone is not the result of dynamic vs. electrostatic transduction. It comes from a different optimization. Most dynamic vocal mics are tuned to offer more proximity effect and less HF response. If a condenser mic was tuned to reinforce chest voice and reduce HF, the difference would not be so abrupt. Historically, condenser mics were designed for different criteria, it's only recently that manufacturers have chosen to offer condenser alternatives to popular dynamics. I believe Neumann have done a good job with their KMS105, and Shure with their SM87.
Actually, after having used many dynamic mics in live situations (Beyer M67 & M88, EV RE16, Shure SM58 and one that remains a favourite, the unduly overseen Samson S12), I have switched to a Zoom SGV6, a unique triple-element design that provides excellent feedback and room rejection all across the frequency range.

I'd like to see more new options in dynamics.

Me too. I'm a sucker for "dedicated" mics. I'm not curious for a general purpose mic. I listen when I see a mic that's presented as specialized.
I think the world has not enough Senn E609/906 or AKG D12 type mics.

Shure could probably reissue a true SM-5B pretty easily, an make a killing! Not that much different from a 57 inside...although there's a little more to it than that.

I believe Shure have transitioned from the SM5 to the SM7 because of manufacturing optimization. Probably more automation, less handwork. It's very hard to convince R&D (and bean counters) to go back.

 

[ricardo]

The definitive paper on Loudspeakers as High-Quality Microphones is of course, by Great Guru Baxandall
https://aes2.org/publications/elibrary-page/?id=3776

It hints at what you must do if you want flat response.

If you just want your kick drum to boom more, you don't need flat response.

I've played with the type of amp he recommends and came to the conclusion that his transformer solution(s) was(were) probably the easiest & most elegant way(s) to do it properly.

This leads to a good way to assess the sound of a small speaker in a room.

---

BTW, the reason why many 'new' microphone capsules look like headphone capsules was cos in da 60s & 70s, the first high quality headphones used modified microphone capsules .. eg the Sennheiser, AKG & Beyer headphones of that time.

The Japanese, and IIRC the Koss, phones used cheapo small speakers.

---

600R microphones have some advantages. They are usually closer to Ropt in modern preamps so better S/N. The CONS are slightly less EMI/RFI immunity .. and more importantly, more fragile voice coils.

But Sennheiser HD414, one of the first high quality headphones, was 600R

 

[abbey road d enfer]

The definitive paper on Loudspeakers as High-Quality Microphones is of course, by Great Guru Baxandall
https://aes2.org/publications/elibrary-page/?id=3776

I'm quite familar with this paper and, with due respect, I think he neglected some acoustic aspects, particularly diffraction, which results in significant frequency response issues.
For a 6.5" speaker, the first response peak is at about 2kHz, followed by a dip at 4kHz and another peak at 6kHz.
Collateral is directivity issues, with a corresponding narrowing at the peak frequencies, and widening at the dip frequencies (actually it's the reason for these peaks and dips).
One can experience that by listening to a wide-band loudspeaker and moving in front of it, the effects are similar.
That's why it never became popular IMO.

It hints at what you must do if you want flat response.

If you just want your kick drum to boom more, you don't need flat response.

Indeed, that's what most people expect. In this role, flat response is not in the wish list.

I've played with the type of amp he recommends and came to the conclusion that his transformer solution(s) was(were) probably the easiest & most elegant way(s) to do it properly.

In a typical application, close micing of kick drum, cajon, bass amp..., noise is not an issue, due to the relatively high spl. I've experimented with a direct connection from the voice coil to the preamp's input and never wished I had more gain, on the contrary.
Now I don't like the result, I think bass is unnaturally inflated. I leave that to hip-hop and rap producers.

 

[ricardo]

I'm quite familar with this paper and, with due respect, I think he neglected some acoustic aspects, particularly diffraction, which results in significant frequency response issues.
For a 6.5" speaker, the first response peak is at about 2kHz, followed by a dip at 4kHz and another peak at 6kHz.
Collateral is directivity issues, with a corresponding narrowing at the peak frequencies, and widening at the dip frequencies (actually it's the reason for these peaks and dips).

GG Baxandall was aware of these issues. But he was expecting you to use a complete speaker that presumably had been designed to be 'flat'.

The resultant 'microphone', assuming you used his special amps, would have the same response as the speaker and also it's directivity.

That's the basis of the 'new' method of assessing the sound of a speaker in a room. If you used an identical speaker as a microphone ala Baxandall, the resultant sound would have double the response & directivity effects in the room.

 

[kingkorg]

impossible to have a good capsule in China!

If this company failed it doesn't mean your statement is true. China doesn't make capsules, China is a country. But if countries made capsules the closest would be 797 audio which is state owned, makes chinese space program equipment, and exceptional capsules both dynamic and condenser. Sm57 is a crappy mic, even it's creator thought that way. He failed to make of it what he intended to. The fact it is widely used has to do with other things. Tons of great capsules made in China. Not necessarily available for OEM.

in my opinion it is 10x complicated to manufacture than a K67 static capacitor capsule!

If you believe this, you don't understand how condenser capsules work. There's nothing static about condenser capsules. And it is extremely difficult to get even the simplest capsules right. Which is why we are starting to see just recently WIDELY AVAILABLE accurate replicas of k67.

Even the best, highly regarded boutique condenser manufacturers have some basic issues with film consistency, stability, dirt, residue, tolerance, performance over time +++ Many chinese factories make 30$ capsules that don't have any of these issues.

 

[abbey road d enfer]

GG Baxandall was aware of these issues. But he was expecting you to use a complete speaker that presumably had been designed to be 'flat'.

A transducer of more that 1/2" in diameter can be reasonably flat (20-20k) only in one direction, generally on-axis.
Loudspeakers can be EQ'd for on-axis linear response, but it implies a specific mounting and a privileged listening position.
Microphones OTOH pick up sound from every direction; LDC's are known to have issues with "coloration" of off-axis sounds. A loudspeaker will have problems, unless it picks up a single source in an anechoic environment.

The resultant 'microphone', assuming you used his special amps, would have the same response as the speaker and also it's directivity.

And that's the problem. Directivity issues with louspeaker can easily be solved by imposing a dedicated listening poit, microphones can't be sold with a warning "not to use with large sound sources or in reverberant environment"

That's the basis of the 'new' method of assessing the sound of a speaker in a room. If you used an identical speaker as a microphone ala Baxandall, the resultant sound would have double the response & directivity effects in the room.

I understand that, as a way of assessing a louspeaker/room combo, but not as a general purpose microphone.

 

[kingkorg]

A blast from the past, just to tickle imagination.

A 58...
https://www.globalmediapro.com/dp/A032C4/797-Audio-CD58-Dynamic-Microphone/

 

[MicMaven]

... one that remains a favourite, the unduly overseen Samson S12), ...

Interesting. I have a nice $65 Samson R31s which I consider is a good general purpose model. I purchased my $65 Samson R31s new for just $15 - one of my better moves.

Trivia Factoid: The R31s has the same dynamic cartridge as several other low cost models from other companies, including the Musician's Gear M1000 and Superlux ECO-88. I use it making A-B-C comparisons with more expensive microphones like the $140 HEIL PR-20 favored by many snobbish ham radio operators. My crummy voice sounds nearly the same with all of them, from which I argue ham radio operators do NOT need expensive studio grade microphones. Subtle differences discerned by professional recordists in the studio are surely lost on ham radio transceivers processing just 2,700Hz audio and RF bandwidth with circuits rated as high as 10% THD! (But, as we all know, some guys just WANT to believe spending more money on equipment makes them a better operator.)

My take is ... dynamic microphones can be a very appropriate, cost-effective choice for some applications. But, heck, YOU GUYS KNOW THAT!

I suspect the trick is in convincing consumers that both types, dynamic and condenser, have their respective places in and out of the studio. I think.​

James


[PS - I appreciate your letting me participate in the discussion and allowing me a sense of humor along the way!] JR

 

[MicMaven]

Tons of great capsules made in China. Not necessarily available for OEM.

Many Chinese factories make 30$ capsules that don't have any of these issues.

I have studied/tested a number of low cost Asian-made OEM dynamic cartridges, all of which cost less than $15 and most cost than $10. I believe they are very competitive and represent good value for money spent. I have found only a few which I consider completely unusable.

I install my favorites in bona fide Shure Beta57a handles (with no logo) purchased from an authorized vendor on eBay for a mere $15, delivered. Suitable grilles are just $4. Voila! Nice DIY microphones for family, friends, and others at very low cost. I recently donated one to a local charity, making sure it understands their DIY essence, as they lack any brand logo or manufacturing mark. Strictly DIY.

While my wife and I still prefer my modest-cost Sennheiser, Shure, Audio-Technica, HEIL, Samson and other well-known brand name dynamic microphones, I believe several of the Asian-made OEM cartridges are worthy contenders despite the wide price disparity. I also expect they will improve substantially in the near future. (Of course, some of them really stink, but then they only cost around $5, and we cannot expect to fool all of the people all of the time!)

[A brief summary, a crude beginning and work-in-progress, is attached for what it may be worth - or not.]​

James

 

[abbey road d enfer]

impossible to have a good capsule in China!

Quite surprizing, since several AudioTechnica mics are actually MIC.

 

[KrIVIUM2323]

impossible to have a good capsule in China!

Well almost 12 years ago i was introduced to a chinese brand called MicW which produce some measurement/high quality omni mics.
I urge you to listen to one of them and then tell us if they don't know how to make a good capsule.
Of course they don't cost 2 dollars a piece on Wish or Aliexpress...

As wide is the country is the offer of products they make ranging from very bad to very good.
Don't let hubris take over our view of eastern world,or we will pay it one way or another sooner than later. There is some really serious people in there, able to do some really serious stuff.
It's true for India too.

 

[EricN]

Its pretty simple, cost of entry; I can buy every part of the most condensers from an OEM, for dynamics I would need a significant investment in machinery.

 

[OneRoomStudio]

Its pretty simple, cost of entry; I can buy every part of the most condensers from an OEM, for dynamics I would need a significant investment in machinery.

That doesn't really make sense. Sure, you can buy finished condenser capsules "off the shelf," but that would be the equivalent of buying a moving coil assembly off the shelf - no machinery needed in either case. If you're making condenser capsules yourself, you absolutely need the the machinery to drill the backplates, stamp/cut the spacers, cut the film for the diaphragm, etc (just ask @soliloqueen)....the same way you would need machinery to make the components of a moving coil mic.

I think what you're saying is that there are already a lot of condenser capsules and parts available to purchase? But that gets back to my original question - why so many condensers being made and so few dynamics?

I think lack of demand is the real answer, but not a very satisfying one.

 

[soapfoot]

Can you buy (say) an RE20 body off the shelf?

Because even if the moving coil assembly is right, it won’t sound close to correct in a different body

I think that’s what they may have meant