Sennheiser MKH20 Ring responses

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Sennheiser MKH20 Ring responses

Post by Hugh Robjohns »

Sennheiser's MKH20 omnidirectional microphone is supplied with a flat rubber ring (item: MZR-20) to acoustically alter the mic's frequency and polar responses in a broadly similar way to the use of 'Acoustic Spheres' available for other brands of omnidirectional microphone.

However, the published chart detailing the way it changes the frequency response is often lost and was hard to find on the Internet — and very difficult to read even when found — so I've carefully re-drawn it here for the benefit of future enquirers.

The ring has an outer diameter of 35mm, an inner diameter of 25mm, and is 6mm thick. I've not found a generic supply, but I'd suggest searching for neoprene washer M25 x 35.00 x 6mm.

The pressure ring must be fitted such that it is flush with the top of the microphone housing.

The information Sennheiser provides with the ring states "This pressure build-up ring increases sensitivity of the MKH20 within the frequency range 4 to 10kHz by approximately 2dB. In conjunction with the diffuse field equalisation the ring enables an easy matching of the frequency response to a given recording situation."
MKH20 Ring responses.jpg
In essence, the ring provides a modest 2dB boost between 4-10kHz, centred on 8kHz. When used with the microphone in its flat response it also provides a gentle roll-off above 15kHz. The ring can be used in combination with the microphone's diffuse-field correction EQ, if desired (the diffuse-field switch introduces a high-shelf boost reaching +6dB at 10kHz).

The microphone's polar response is naturally more directional at high frequencies, with the front/back ratio falling above 1kHz to roughly 5dB at 6kHz, and reaching 15dB at 16kHz. Fitting the ring is likely to increase this ratio further above 4kHz but, sadly, Sennheiser has not (AFAIK) published polar-pattern plots detailing the resulting changes.
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Re: Sennheiser MKH20 Ring responses

Post by forumuser840717 »

I always find that the biggest sonic improvement comes when one drives through the 4" nail to hold the ring in place :tongue:
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Re: Sennheiser MKH20 Ring responses

Post by Hugh Robjohns »

:lol:
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Re: Sennheiser MKH20 Ring responses

Post by MOF »

I always find that the biggest sonic improvement comes when one drives through the 4" nail to hold the ring in place :tongue:

Do you have any advice as to what sort of hammer one should use? Just asking for a friend. :lol:
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Re: Sennheiser MKH20 Ring responses

Post by jimjazzdad »

All joking aside, the MKH20 is a fantastic mic; its a pity that Sennheiser has stopped making it. I have not done a head-to-head comparison with the MKH8020 (I don't have access to a pair of the newer ones) but I have read that they are "not quite the same". Any opinion Mr. Robjohns? A pair of closely spaced MKH20 is my all-time favourite setup for grand piano. Your post has reminded me I must try the rings when using them as main pair / room mics.
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Re: Sennheiser MKH20 Ring responses

Post by Hugh Robjohns »

A friend has some 8020s which are excellent, but when I compared them I ended up preferring the MKH20s -- although I'm struggling to come up with a rational reason for that preference.

I'm a fan of the MKH mics in general and have rather a lot of them, although one of my (five) MKH20s has started whistling at around 16kHz so it needs a visit to the lab to be realigned.
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Re: Sennheiser MKH20 Ring responses

Post by John Willett »

I could have sworn I have seen a polar plot of the MKH 20 with ring, but I cannot be sure - I will have a look.

In many ways I still prefer the MKH 20/30/40 series to the 8000 series - but I do have pairs of both MKH 40/8040 and MKH 20/8020 in both versions.

Though I now do tend to use my Gefell M221 omnis on piano more (nickel diaphragm capsule) ;)
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Re: Sennheiser MKH20 Ring responses

Post by Arpangel »

Hugh Robjohns wrote: Tue Sep 21, 2021 10:50 am A friend has some 8020s which are excellent, but when I compared them I ended up preferring the MKH20s -- although I'm struggling to come up with a rational reason for that preference.

I prefer the MKH20 too, I think the 8020 "may" sound brighter overall, all I’m doing is asking if you can confirm this, or not, just wondering what differences people are hearing?
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Re: Sennheiser MKH20 Ring responses

Post by VoM »

Thank you so much for posting this, very interesting and helpful!
My two rings for my now very old MKH20 have disappeared, does anyone know of a supplier? I can't find them online. I think while I am waiting to find replacements I will try some O rings since you provided the dimensions.
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Re: Sennheiser MKH20 Ring responses

Post by VoM »

Here is the official frequency chart with the ring (from gearspace)
https://gearspace.com/board/attachments ... mkh-20.pdf
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Re: Sennheiser MKH20 Ring responses

Post by Hugh Robjohns »

VoM wrote: Sat Mar 25, 2023 11:45 pmMy two rings for my now very old MKH20 have disappeared, does anyone know of a supplier?

Anyone who provides Sennheiser spares should be able to get them. The part is identified as the MZR-20 Damping ring.

Here's a supplier listing:

https://artaudioparts.com/en/035634-mic ... ser-mkh-20

I think while I am waiting to find replacements I will try some O rings since you provided the dimensions.

Try searching for neoprene washers, rather than O rings. The latter have a round profile but you need a flat disc profile. M25 x 35.00 x 6mm
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Re: Sennheiser MKH20 Ring responses

Post by Hugh Robjohns »

VoM wrote: Sun Mar 26, 2023 9:21 am Here is the official frequency chart with the ring

The chart I included above is the same graph, but meticulously redrawn with coloured traces so you can actually see the responses....
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