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Acoustic modification accessories - changing characteristics

By using DPA Acoustic Modification Accessories you can acoustically alter the behaviour of your microphone. From a single 4006 you can achieve different frequency responses and directional characteristics without compromising noise, phase-shift or distortion! Every console or outboard EQ – no matter the quality – will to some degree add these affectations to the sound color.

Acoustic Pressure Equalisers
The Acoustic Pressure Equalisers – APEs – are passive acoustic processors functioning as both spatial and spectral equalisers. They use diffractions on the surface to modify the sound field near the microphone diaphragm. This technique is only possible on omnidirectional pressure microphones.

Two primary changes occur:

1. An upper-midrange/high frequency boost (without changing the low end) due to the pressure build-up at certain frequencies depending on the element’s size.

2. More directionality at higher frequencies (focus).

A presence (upper-midrange) lift is often desirable in rhythmical genres, to make a voice or an instrument cut through a mix or simply to make it more intelligible or well-defined. For symphonic music, the frequency response of certain legendary vintage types of microphones can be obtained using one of the APEs. However, you will achieve a much higher degree of naturalness and detail when using a precision handcrafted 4003 or 4006.

APE diagrams
APE30RS, 30 mm ball:
On-axis response of DPA 4006A with APE30RS 
Directional characteristics of DPA 4006A with APE30RS (normalized)

APE40RS, 40 mm ball
On-axis response of DPA 4006A with APE40RS 
Directional characteristics of DPA 4006A with APE40RS (normalized)

APE50RS, 50 mm ball
On-axis response of DPA 4006A with APE50RS 
Directional characteristics of DPA 4006A with APE50RS (normalized)

Interchangeable grids
The interchangeable grids are not only for protecting the microphone diaphragm, but are as much an important part of the microphone’s acoustical design. They are used to obtain a final adjustment of the frequency response and to control the behaviour of sound waves on the diaphragm. A relevant use of grids is adaptation of the microphone’s frequency response to the sound field. In the diffuse sound field a high frequency loss will occur. This can be compensated for by using the DD0297 Diffuse-field Grid which – as with the Acoustic Pressure Equalisers – will work as an acoustical object over the capsule.

The DD0254 Close-miking Grid will gently roll-off the highest audible frequencies to make the microphone’s response softer for the often intense high frequency character from sound sources recorded at very short distances.

The UA0777 Nose Cone makes the microphone perfectly omnidirectional in the audible frequency range and can for instance be used in optimal acoustic environments where every direction should be reproduced uncolored. 

Grid diagrams
DD0254 Close-miking Grid
On-axis response of DPA 4006A with Close-miking Grid DD0254
Directional Characteristics of DPA 4006A with Close-miking Grid DD0254

DD0297 Diffuse-field Grid
On-axis and diffuse-field responses of DPA 4006A with Diffuse-field Grid DD0297 
Directional characteristics of DPA 4006A with Diffuse-field Grid DD0297 (normalized) 

UA0777 Nose Cone
Diffuse-field response of DPA 4006A with Nose Cone UA0777
Directional characteristics of DPA 4006A with Nose Cone UA0777 (normalized) 

It’s like using an equaliser – but then again not...
Whenever you switch in a filter or an EQ electronically it will influence the total sound field picked up by the omni microphone. You actually do a '360 degree equalisation' of the microphone signal. Alternatively, by using acoustic modification accessories, you can choose to make the desired frequency alteration in the direction you actually need it. The change is made acoustically – right at the diaphragm.

Every craftsman will bring along his toolbox to optimize his work with the ability to always choose the right tool for the specific job. For the ambitious and discerning sound engineer, the DPA Acoustic Modification Accessories are serious tools to claim.


Se forklaring på fagudtryk i DPA's ordbog (engelsk)