Replacing built-in mics

ullanta said:
Also, just out of curiosity about the 4-mic mystery:

Are you certain of how the mics are combined? That is, are you certain which mics feed which channels?
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Re: a), yeah, if I'd have a cable splitter I could do that. But I should be able to rig something for that test. As it is, I am quite happy with using the stereo shotgun, and two cardioids, but I'll do that a) as a test for sure.

Re: mic mystery: it's not really a mystery to me anymore. In fact, I think it's quite clever if I am judging this right. They are basically squeezing the best audio out of what have to be pretty crappy mics. Also, there is no real question as to which mic input does what. There's two LEFT channels and two RIGHT channels, each having one with a higher [sounding] frequency, and a lower/duller [sounding] frequency. Combined they sound pretty decent.

Good suggestions, as always Barry; and much appreciated. It was great to have you ask/comment/suggest things throughout this process...
Cheers!
 
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vidled said:
Re: mic mystery: it's not really a mystery to me anymore. In fact, I think it's quite clever if I am judging this right. They are basically squeezing the best audio out of what have to be pretty crappy mics. Also, there is no real question as to which mic input does what. There's two LEFT channels and two RIGHT channels, each having one with a higher [sounding] frequency, and a lower/duller [sounding] frequency. Combined they sound pretty decent.
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Sure, I'm just curious. It doesn't quite make sense to me unless the mics themselves have different frequency responses. Of course I also fantasize about the complex cutting edge processing they MIGHT be doing... that is, say, using FRONT and BACK omni pairs (rather than LEFT and RIGHT pairs), and some phase-difference processing to generate left and right images - or one set of mics tuned to primarily pick up camera noises, which are then "phased out" of the other mic's signal... I mean, sure, you're most likely right, but the remote possibilities are interesting!


Good suggestions, as always Barry; and much appreciated. It was great to have you ask/comment/suggest things throughout this process...
Cheers!
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Thanks! But come on, nothing compares to the appreciation the rest of us feel for your willingness to actually investigate and test all this!
 
This is very cool, Vidled, you could start a buisness where you mod people's HVX's for them- it would void the heck out of the warantee, but folks will do some crazy stuff to get 2 more discrete channels of audio.

-Tom
 
So, here's the final audio test using only the internal microphone circuitry of an HVX200.

There's four different parts:

1) Two Studio Projects C4 cardioid condensers feeding only two channels of the 4 internal mic channels.
hvxmic1.gif


2) Two Studio Projects C4 cardioid condensers feeding the two other channels of the 4 internal mic channels.
hvxmic2.gif


3) Two Studio Projects C4 cardioid condensers feeding all 4 internal mic channels.
hvxmic3.gif


4) Two Studio Projects C4 cardioid condensers feeding two channels; and a stereo Audio Technica AT835ST mic feeding the other two channels.
hvxmic4.gif


Audio file (WAV, 48KHz, 10MB)
 
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tomk358 said:
This is very cool, Vidled, you could start a buisness where you mod people's HVX's for them- it would void the heck out of the warantee, but folks will do some crazy stuff to get 2 more discrete channels of audio.

-Tom
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Yeah, it's pretty cool now with this setup.

It's one thing to rip apart my own cam an hour after receiving it from UPS, but I'm not sure I'd be willing to do this "procedure" on others' cams....well it'd depend on the demand I guess. But I think most will probably just wait for RED and get their 4 channels there! :)
 
I am wondering if there would be an interest in making this modification for other HVXs out there, and what it would be worth to someone. Now, I don't intend to do this work myself, but I know of a place that would be ideally suited for this kind of work. Naturally any existing Panasonic warrantee would be voided, but I guess many cams are coming out of their original warrantee anyway.

Maybe this mod is something that is useful to others?

The main benefit is that the internal mics can be bypassed and other, external mics used in their place.
I haven't used internal mics on a cam for years, due to poor quality sound (mic quality and mic placement being the problems).

So for HD recordings with the HVX200, 4 SEPARATE CHANNELS can be captured, where all four channels can come from external mics (or mixers). 2 of these channels can come from the standard external mic inputs of the HVX200, INPUT 1 and INPUT 2, and two more channels can come from 4 NEW EXTERNAL CONNECTIONS, INPUT 3a & 3b and INPUT 4a and 4b.

The modification that I made works perfectly fine, although I'd change the following if I'd to do it again:

1) Make the existing internal mics switchable, i.e. either use the existing internal mics, or switch to externally connected ones.

2) [Possibly] use only one break-out cable, as opposed to the current mod, which uses 4 cables.


So, what would this modification be worth to someone wanting it done professionally? Any feedback much appreciated.
 
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I would be interested once my warranty was done for if the price was low enough to match the the achievable quality. Can you give us a ball-park figure?

Wish list:
_a nice little (black :) ) input box that is not in the way of light and shotgun mounts
_a switch on this box (as you suggested) to switch the modification on/off
_two inputs set up as your #3 diagram (you could offer two different mods)
_your site to host the following: original mic and some speech, same room same person speaking on setup #3
_your site to host these shots: the same car driving by type of shot like you did earlier but shot with two HVXs running side by side (same time) one running stock and your modified HVX running two (same) semi-directional shotgun mics set up so that they are aimed left and right respectively but overlapping their hot spots a bit
_some diamonds encrusted on it
_a bonus year subscription to Playboy
 
When I connect external mics to my HVX, the camera mics seem to record at default levels (that are uncontrollable) on channels 3 & 4. When I import into FCP, I end up with four channels full of sound. Channels 1 & 2 being my external mics.

My big question is, if you want better sound, why not skip voiding your HVX warranty when you crack open the case and just buy good quality external mics? Just asking.
 
Thanks USLatinContent....
a lot of your requests can be done...the Playboy one might be a little too much to ask for though... :)

BenB said:
My big question is, if you want better sound, why not skip voiding your HVX warranty when you crack open the case and just buy good quality external mics? Just asking.
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Okay, yes. I may have failed in explaining this correctly, or you didn't read the whole thread: this modification allows the recording of 4 channels with 4 external mics. 2 from the external connectors, Input 1 & 2, and two MORE external mics going to the internal cicuitry Channel 3 & 4.

Cheers.
 
vidled said:
Okay, yes. I may have failed in explaining this correctly, or you didn't read the whole thread: this modification allows the recording of 4 channels with 4 external mics. 2 from the external connectors, Input 1 & 2, and two MORE external mics going to the internal cicuitry Channel 3 & 4.
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It already does this when I hook up external mics, I get four tracks of sound, 1&2 are my external mics, 3&4 are the on-board mics at some pre-set level. Will this be giving us control over the sound levels of the on-board mics in this configuration?
 
BenB said:
...3&4 are the on-board mics at some pre-set level.
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That is what changes!

"EXTERNAL MICS going to the internal circuitry!"

You can use 2 EXTERNAL mics INSTEAD of the on-board mics. They are controllable though an external mic pre-amp. So with this mod, your "uncontrollable" on-board mics are replaced with any external mics of your choosing (which go through a mic pre amp, and then into the mod-box). You ALSO have avalable the normal INPUT 1 & 2 external mic inputs as well of course.
 
I'd be very interested... I think my warranty's almost up, too! I'd also want the #3 setup, and the mod/original mic switch.

I picture perhaps a breakout cable to a Beachtech-style box? Or even modification of, say, a low-cost (SignVideo?) Beachtech-ish box to capitolize on it's level controls, grounding, and such.

Or, dare I say it, just use the dreaded mini stereo jack, which would be small, and allow the user to choose from a large number of Beachtech-y front ends, with phantom power if they want, etc. That would give you the simplest mod and the user the most flexibility....

I'd love to pay just a few hundred $$ for this...
 
wait, so you say that it could be made so the user/customer chooses the the pre-amp? (I'm sorry if I can't keep up with you guys on this stuff)
So if I understood correctly:
_If space allows for it there could be a switch on the top of the existing mic casing for the on/off mod function! :thumbup:
_Small phono jacks (mini headphone jacks) on the side of the original mic casing but most likely there won't be enough space or it would require too much cutting and so on so: a very small box-like attachment for these jacks so that there won't be dangling wires, no wait! maybe just a nice looking tiny strong well positioned clip to secure the wires which only stick out about an inch and a half or two! Black wires black clip, all done nice and clean, yea! do the jacks with the threads to secure the connection! that would be great, and keep the cost down for you and more people would consider it.
_You could then offer a guide for customers to pick their preamp and if volume is high enough you could purchase one or two good choices in bulk...

then again I don't know if this is what you guys were getting to, was it? Or would this limit the quality of the sound?

If you can find a place to do a good job for you, then I am sure you'll be able to make a little venture of this. Find out how much it woud cost you per item first.
 
Thanks USLatinContent and ullanta,
I'll be looking at some things you've suggested (to make it more convenient, less expensive, and overall better) over Thanksgiving.

I may even modify my HVX again, to test a few things.

The Beachtek idea is also a good one, as they offer some products for "this kind of application" - the DXA-10 might do the job, and at $240.00 not too expensive.
 
There's a company in L.A. called Audio Upgrades:

http://audioupgrades.com/index.html

(818)780-1222

...run by a guy named Jim Williams, who might be just the man to do this sort of modification. He does custom audio circuit mods to a very large list of pro audio devices including consoles, tape machines, mics and more. I had him do a full set of modifications to my 32 channel mixing console, and he did a great job.

I bet he'd be quite willing and able to do a very professional built-in mic mod to the HVX, including solving all circuit and level mysteries, for a reasonable price. If anyone is game, give him a shout. Tell him I sent ya...
 
Anyone go through with this by themselfs yet?

Any interest If I do it and make a video about it?
 
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