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[quote="danielruder"]
The mics' frequency response is very non-linear. In the design, he decided to sacrifice frequency response for "time coherence," or something like that. Basically, they're extremely time accurate, and not especially frequency accurate. So, to compensate, you equalize the sound after the recording (or maybe you can eq before - I'm just going on what I was told).[/quote]

The thing is that it seems really challenging at a component level to build accurate de-emphasis filters that correct frequency response without introducing serious time errors ... making the whole idea of time coherence iffy.

Maybe there is a microprocessor in the mics that performs the level correction ... without phase shift and time "errors".

The fact remains that microphones, fuck all instruments, sound special and especially useful in certain contexts precisely because of the not-perfect time coherence or frequency response.

It's interesting that the Earthworks mics, touted as time-coherent as pointed out--seek SMALL air pistons to achieve their goal while these mics do exactly the opposite by using a horn (or hearing bell). Very wild proposition, worth looking into.


I'd be happy to test the 'time coherence' vs. flatness if someone would be so kind as to send me one of these (intriguing) lathed oddities.

ptay wrote:

danielruder wrote:The mics' frequency response is very non-linear. In the design, he decided to sacrifice frequency response for "time coherence," or something like that. Basically, they're extremely time accurate, and not especially frequency accurate. So, to compensate, you equalize the sound after the recording (or maybe you can eq before - I'm just going on what I was told).

The thing is that it seems really challenging at a component level to build accurate de-emphasis filters that correct frequency response without introducing serious time errors ... making the whole idea of time coherence iffy.

Exactly, this is why I suggest a software solution - ideally using one of the many linear-phase eq processors available.
The Model A is a passive design for this reason.

Maybe there is a microprocessor in the mics that performs the level correction ... without phase shift and time "errors".

While a hardware implementation is conceivable, the Model A was designed with software equalisation in mind.

This serves several purposes.

Firstly, this ensures that the resolution of the unit is not held back by analogue processing limitations - limitations of both physics and of economy.

Secondly, this ensures that the microphone is only limited by the pre-amplifier & converter it is connected to - which means that future developments in pre-amp/converter/EQ technology will not be limited by internal circuitry.

Thirdly, this allows flexibility in useage. For example, if the microphones are driven hard into a tube-amplifier stage, the result is very different to that of a 'clean' solid-state approach. Since the microphone is passive, either approach can be taken.

Similarly, with post-equalisation the user is free to use whatever post equalisation is subjectively prefered. A 'flat' response is not always wanted, so the user is free to decide according to taste.

In practise, an EQ processor (software or hardware) is only as good as the source. If there are resonance issues in the source, equalisation has great problems, and conversely where the signal is free of time-domain error, equalisation is essentially transparent.

The fact remains that microphones, fuck all instruments, sound special and especially useful in certain contexts precisely because of the not-perfect time coherence or frequency response.

I'm not sure I would agree but certainly the potential efficacy of units such as the 'liquid channel' has never been greater.

It's interesting that the Earthworks mics, touted as time-coherent as pointed out--seek SMALL air pistons to achieve their goal while these mics do exactly the opposite by using a horn (or hearing bell).

Although I can't speak for earthworks, in my view this approach (although universal) is a contradiction. This is like saying that the microphone would be more accurate in a vacuum!

For my work, I look primarily at the mechanical system of the microphone diaphragm.

This contradictory system is a spring restrained body, both held in place and able to move with sound waves.

Since the spring restoring force is proportional to displacement, acoustic impedance becomes critical.

The energy transfer (governed by acoustic impedance difference) from the air to the diaphragm is in direct opposition to the spring restraints and so this limits the effective mechanical resolution (or dynamic range) of the system.

As acoustic impedance is raised, energy transfer is also raised and the spring restraints become relatively less significant.

This is where the 'freedom of dynamics'/'natural sound' comes from.

Some recent stereo pair recordings:

orchestra with piano - recorded at 15-20 metres
Gregorian choir - recorded at 10-15 metres

Andy