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-   -   MIC Input Attenuator (https://www.dvinfo.net/forum/jvc-everio-gz-hd-gz-hm-series/111326-mic-input-attenuator.html)

Dan McCann December 31st, 2007 11:08 PM

MIC Input Attenuator
 
Since the HD7 does not provide for MIC level setting, does anyone have a design for an inexpensive MIC input attenuator? I'd like it to be variable since I can't always control the level of the source that I'm recording. My recording is going to include footage such as rock shows in small venues that can see 145dB levels; top fuel dragsters and top fuel funny cars up close and personal (like 10 feet away) that could also get in excess of 145 dB. I recorded a show in the small venue and the levels were so high, all I got was distorted the recording was worthless.

Small parts from the local Radio Shack would be preferred. Also would like to hookup in ear monitors so I can ensure I set the levels appropriately.

Thanks,
Dan

Gerry Gallegos January 2nd, 2008 08:17 AM

Mic attenuator
 
Dan.

What mic are you using?
does it require Phantom Power?
does it have an XLR connector?

Look at mic input boxes from Beachtek, Studio 1, and other similar.

If you need to provide Phantom to a mic then perhaps look at the Sound Devices stuff, they have a great reputation.

as far as I know there is no way to manually attenuate the internal mics on the HD7.

and as far as "true" 145db there are not many mics period that can handle that, without distortion, and that would "Kill" most condensers. Most rock shows stay below 112db, (at least ones that are intended to sound good) and the really great sounding concerts stay below 105db and lower, not to mention local laws limit this. permanent hearing damage starts way way below 145db if even exposed for one second.

unfortunately there is no "Cheap" (radio shack parts)way of variably attenuating an external mic and do it "properly". it can be done with a good electronics part store (and serious electronic geek skillz), but you still going to spend a bit to do it right, so its easier to just get one of these XLR input boxes.

Kerrod McShane January 4th, 2008 02:14 AM

Hey Dan, I can't help you with your Attenuator question but you did mention about monitoring your audio, so I thought I'd share my 2bob in regard to what I do for monitoring.

I just wanted to hear the audio live while I was recording because even though I am using the Rhode Video Condencer mic with a "furry cover" (I can't think what there called) I sometime get wind noise. So I figured it I could hear the audio while recording I may be able to stop the whistling whith a simple wind sheld. Anyway I ducked down to Jaycar and got a 4 pole 3.5mm male audio jack to go in the AV jack on the gzhd7, then an audio extension cable with 3.5mm female jack on one end to accept my earbud jack.
Got home cut the 3.5mm about 3cm from the female end and soldered it to the 4 pole jack as follows.
White cable = tip of 4 pole jack.
Copper cable= 3rd from tip.
Red cable = Base or 4th from tip.
Some electronics whiz could probably tell you if that is/or is not the correct order regarding L or R, but I't does the job for me and I hope it helps,
Regards,
Kerrod.

Dan McCann January 7th, 2008 11:07 PM

These are Core Sound stealth mics with a 9v power supply. The connection is 1/8" stereo so they plug right into the HD7 mic input. The venue that is so loud is a club that has a room about the size of a 3 car garage and they run 10k watts on their sound system. I rarely go there, but when I do, I'd like o try recording. I personally don't like it that loud, but when ZO2 comes into town, I try to catch them. As far as the funny cars, well, nitromethane burns at a certain rate and that cannot change. In either case, the extreme loud levels are momentary, but they do happen, and I'd like to attenuate the output levels of the mics. If I can't do it in the recorder, I can always record the sound seperately and sync the audio and video in post processing in Vegas...but that's a royal PITA and I'd rather have only one piece of equipment if I can. I'll have to look into Beachtek and the others.

Kerrod, that's exactly what I want to do. I'll be using a set of Westone UM2's for monitoring...so determining the sound level and quality will be pretty easy to do once I get the attenuation deal solved.

Thanks,
Dan

Gerry Gallegos January 8th, 2008 07:44 AM

headphone monitoring on HD7
 
Well, after much wait, my headphone amplifier housed in a nifty Altoids tin finally arrived... I managed to find a 3.5mm stereo to 2 RCA female short adapter, and connected to your plain AV cable for camcorder and "Viola'" I now have a pretty powerfull headphone amp that is capable of driving my MDR 7506 way beyond what my ears can stand with no distortion, and did I mention you get a constantly variable volume control?... just thought I would report here for all you HD7 users. the amp can be purchased on "the big auction site" for about 40 bucks , I think. and you can either make your own cable or modify a spare AV cable, and have your headphone solution all worked out.

Steve Arnold May 19th, 2008 06:12 PM

Quote:

Originally Posted by Gerry Gallegos (Post 804667)
Well, after much wait, my headphone amplifier housed in a nifty Altoids tin finally arrived... I managed to find a 3.5mm stereo to 2 RCA female short adapter, and connected to your plain AV cable for camcorder and "Viola'" I now have a pretty powerfull headphone amp that is capable of driving my MDR 7506 way beyond what my ears can stand with no distortion, and did I mention you get a constantly variable volume control?... just thought I would report here for all you HD7 users. the amp can be purchased on "the big auction site" for about 40 bucks , I think. and you can either make your own cable or modify a spare AV cable, and have your headphone solution all worked out.

i am going to have to do this too. good lord what a hassle!


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