View Full Version : Low Freq Capture Device for Drum *PIC*
09-28-2005, 10:49 AM
Provided Link: Yamaha SKRM-100 (http://tinyurl.com/cr37t)
A friend came to me knowing i build speakers and asked if something like this could be DIY.
Basically it is a large microphone made with a 6.5" driver that your put in front of your drum. It is suppose to be able to capture "sub-frequencies".
I wonder if the driver is hung in free air or a closed box.
09-28-2005, 11:08 AM
Wow. I would keep it open maybe with the back blocked with damping material. You don't want a peak in response. Also, you need a driver with a low FS, right? The key would be the sensitivity, response and making/getting the right mic pre-amp. I would try it first with no mounting drum (although it looks cool) and either stand it up or hang it up right inside the bass drum for maximum sensitivity.
09-28-2005, 11:22 AM
Provided Link: http://chadgray.info/
There is an AES article on "Shock Mounting"
An Effective Mechanopneumatic Shock Mount for a Dynamic Microphone
Volume 26 Number 9 pp. 623-628; September 1978
The unidirectional dynamic microphone is inherently sensitive to mechanical vibration and therefore requires an effective shock mount. Conventional means of shock mounting, as well as the development of the mechanopneumatic shock mount, are discussed with emphasis on equivalent circuit analysis. The mechanopneumatic shock-mounting system employs an adjustable balancing network to provide vibration cancellation over a relatively wide frequency range. A system is described that has been successfully optimized for a high-quality unidirectional dynamic microphone to attain a significant improvement in mechanical vibration performance without compromising acoustical performance.
Author: Locke, Terry R.
So i am wondering if this is the hard part of building this type of microphone. Finding the right dampening material might be problematic.
Now correct me if i am wrong. I should be able to wire this Dynamic Mic up directly to an amp. I dont need phantom power.
I am going to have to do research on XLR plugs wiring and phantom power.
09-28-2005, 11:51 AM
> Now correct me if i am wrong. I should be
> able to wire this Dynamic Mic up directly to
> an amp. I dont need phantom pow
Go directly into a low Z balanced input. It's a very low Z, actually. For best *possible* signal transfer, you could use a transformer that goes from 10 ohms to 200, but I doubt it's needed.
> I am going to have to do research on XLR
> plugs wiring and phantom power.
"pin 2 hot" - remember that and you can figure the rest out with an ohmmeter if you have to:-). I think there is a primer somewhere on the PE site.
09-28-2005, 01:59 PM
> A friend came to me knowing i build speakers
> and asked if something like this could be
> Basically it is a large microphone made with
> a 6.5" driver that your put in front of
> your drum. It is suppose to be able to
> capture "sub-frequencies".
> I wonder if the driver is hung in free air
> or a closed box.
From the yamaha site:
Polar Pattern Bi-directional
Sounds open back to me.
It's "reverse wired to an XLR jack".
09-29-2005, 05:23 PM
> From the yamaha site:
> Polar Pattern Bi-directional
> Sounds open back to me.
> It's "reverse wired to an XLR
Recording magazine had an article a couple of months back on the same type of thing. They just used a 8" speaker they had laying around and held it in place by just sticking it to a mic stand using the magnet on the back of the speaker.
I know you can connect them backwards for a ~40Hz bass beat into a preamp. Hit with a stick they resonate at Fs. Maybe attached to the drum, they would do the same thing at various frequencies?
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