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Old March 13th, 2008, 02:54 PM   #1
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using beachtek as a mixer

Hey guys, I need ye're heads on this one.

So im thinking of cutting off the mini of the beachtek and putting an xlr plug on.
And using for inputting 2 sennheiser g2 units together into it and coming out of it into my A1 into channel 2. Channel 1 on the a1 is for the on camera mic.

Can anyone see any potential problems with this as I intend to purchase a beachtek for this reason only.
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Old March 13th, 2008, 08:16 PM   #2
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I don't understand...are you looking at a Beachtek that only has one XLR input and a mini jack? I've never seen one. Meanwhile, on Beachteks with two XLR inputs there is a switch that allows you to keep the signals as separate left and right, or to mix them. If you then wanted the mixed signal to be applied to only one channel in the camera you can get a stereo to mono adapter plug.
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Old March 13th, 2008, 09:02 PM   #3
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David, I never seem to be clear enough with my opening questions.

Basically ideally I would have three audio channels but only have two on my camera. These are XLR inputs.

So if i use the beachtek to take in 2 of the 3 ( 2 g2 receivers) and mix them together. Then come out of the beachtek box into one of the XLR inputs on my camera. This is why I have to change the existing minijack to an xlr plug.

Just wondering has anyone done this and what people think of this as an option instead of having to get a good portable audio mixer?
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Old March 14th, 2008, 12:42 PM   #4
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I'd buy a custom cable: mini stereo female to XLR male, and forgo making a permanent mod to the beachtek. If you're handy with a soldering iron, which it sounds like you might be, just go to your local retailer (maybe a Radio Shack) and pick up the parts and put the cable together yourself.

Just a thought...
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Old March 14th, 2008, 01:43 PM   #5
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Quote:
Originally Posted by Ger Griffin View Post
David, I never seem to be clear enough with my opening questions.

Basically ideally I would have three audio channels but only have two on my camera. These are XLR inputs.

So if i use the beachtek to take in 2 of the 3 ( 2 g2 receivers) and mix them together. Then come out of the beachtek box into one of the XLR inputs on my camera. This is why I have to change the existing minijack to an xlr plug.

Just wondering has anyone done this and what people think of this as an option instead of having to get a good portable audio mixer?
I don't think the Beachtek would do a proper job. It isn't a mixer; instead, it's essentially a transformer. Its output is stereo TRS with input 1 (left) on the tip, input 2 (right) on the ring, and ground on the sleeve. When you replace that with the XLR you'd need to put both inputs 1 & 2 hot to the XLR pin 2 and ground to pin 1 and 3 jumpered together. If you were thinking of connecting input 1 to pin 2 and input 2 to pin 3 you'd end up with the two receivers in opposite phase to each other with all sorts of bad sounds possibly resulting. But putting both of them on pin 2 means you're trying to just passively combine the outputs of two active devices, kind of a splitter in reverse, and that's a real crapshoot. Passive splitting usually works but passive combining rarely does.

Why don't you get a real mixer and be done with it? Sure it's more expensive but not all THAT much more if you look at the long-run. Let's say you had a SD 302 ... you'd just plug up to 3 mics or wireless receivers in its inputs and route each of them to either the left, right, or both outputs at the flip of a switch.
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Old March 14th, 2008, 03:18 PM   #6
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Quote:
Originally Posted by Ger Griffin View Post
David, I never seem to be clear enough with my opening questions.

Basically ideally I would have three audio channels but only have two on my camera. These are XLR inputs.

So if i use the beachtek to take in 2 of the 3 ( 2 g2 receivers) and mix them together. Then come out of the beachtek box into one of the XLR inputs on my camera. This is why I have to change the existing minijack to an xlr plug.

Just wondering has anyone done this and what people think of this as an option instead of having to get a good portable audio mixer?
That will work quite nicely. Certainly it's not as versatile as a mixer, but for your purposes your quality should be fine.

But rather than cutting and soldering, I'd keep the Beachtek intact and just get this:
http://www.samys.com/product_detail.php?item=7891

The concerns of combining signals that Steve mentioned apply to using a "Y" splitter in reverse, where the input devices can "see" each other as lower impedances than the camera's input, thus shorting each out to some extent. This is not the case with using the two inputs of a Beachtek and combining them by setting stereo/mono switch to mono.
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Old March 14th, 2008, 03:47 PM   #7
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Originally Posted by David Ennis View Post
That will work quite nicely. Certainly it's not as versatile as a mixer, but for your purposes your quality should be fine.

But rather than cutting and soldering, I'd keep the Beachtek intact and just get this:
http://www.samys.com/product_detail.php?item=7891

The concerns of combining signals that Steve mentioned apply to using a "Y" splitter in reverse, where the input devices can "see" each other as lower impedances than the camera's input, thus shorting each out to some extent. This is not the case with using the two inputs of a Beachtek and combining them by setting stereo/mono switch to mono.
But that's exactly I think is going to happen here - each receiver will see the other. I don't have a Beach schematic handy but I believe the receiver 1 'hot' on input 1 of the Beach will be connected directly to receiver 2 'hot' on the Beach's input 2, if not on the Beach's input side then absolutely on its output, making the whole Beachtek essentially into a "Y" splitter used in reverse. That's the only way the two receivers can end up feeding the same mic input on the camera. Mixers actually use a summing amplifier to combine the signals while maintaining the electrical isolation of the two sources but the Beach is a passive device.

I'll agree that it would be better to use the adapter you suggest than cutting and rewiring because at least with it the Beach remains returnable after the experiment fails <grin>. That adapter is wired with the minijack tip and ring shorted together and connected to XLR pin 2, sleeve to the XLR's pins 3 and 1 jumpered together, BTW.

The bottom line is that I have found just biting the bullet to get the proper tools right from the start is always the cheapest way to go in the long run. Ger, just get a real mixer and be done with it - you don't have to spend a fortune.
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Old March 14th, 2008, 08:56 PM   #8
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If you want 3 inputs on a budget, there is this:
http://www.studio1productions.com/xlr-mix_pro.htm


I would hesitate to chop the cable on a beachtek, especially if it didn't meet your expectations.
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Old March 14th, 2008, 10:18 PM   #9
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Quote:
Originally Posted by Steve House View Post
... making the whole Beachtek essentially into a "Y" splitter used in reverse ....
I don't think the two balanced inputs on the Beachtek see each other at all. They share the same ground, but that's not a signal path for either of them. And having the secondaries of their respective impedance matching transformers in parallel is not the same as having the sources combined in parallel as with a simple reverse splitter.

But regardless of who's correct about the circuitry, I think you might agree that the bottom line is actually that two 600 ohm or so sources comparing each other to the Beach's 200-300 ohm inputs is way different than those two mics comparing each other to a 5k-15k camcorder input. That's why the Beach will absolutely work for Ger where a simple reverse splitter would likely not.

After all, if this were not the case, then wouldn't the stereo/mono output choice would be a complete sham and wouldn't Beachtek have been called on it a long time ago?
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Old March 14th, 2008, 11:18 PM   #10
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found this in the classified section. It's a Promix 3 for $375

http://dvinfo.net/conf/showthread.php?t=116639

Check the classified for other mixers, too. There's gear out there to do what you want without hacking a beachtek.
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Old March 15th, 2008, 06:12 AM   #11
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Originally Posted by David Ennis View Post
I don't think the two balanced inputs on the Beachtek see each other at all. They share the same ground, but that's not a signal path for either of them. And having the secondaries of their respective impedance matching transformers in parallel is not the same as having the sources combined in parallel as with a simple reverse splitter.

But regardless of who's correct about the circuitry, I think you might agree that the bottom line is actually that two 600 ohm or so sources comparing each other to the Beach's 200-300 ohm inputs is way different than those two mics comparing each other to a 5k-15k camcorder input. That's why the Beach will absolutely work for Ger where a simple reverse splitter would likely not.

After all, if this were not the case, then wouldn't the stereo/mono output choice would be a complete sham and wouldn't Beachtek have been called on it a long time ago?
Maybe ... Beach says in the manual that when in MONO mode the two inputs are mixed together. Further, "When in MONO mode [to send 1 input to both L & R outputs], be sure to keep the volume control for the unused channel fully clockwise to reduce the loading effect on the working channel." That indicates to me that they can interact. When the mono mode is engaged, the Beach IS acting as a conventional splitter, taking 1 balanced mono input and splitting it to 2 unbalanced output channels.

Sure wish Beach published schematics in their manuals or on their web site. Are you listening out there, guys?
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Old March 16th, 2008, 01:13 PM   #12
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See this is why I love this forum.
There's nothing you cant find out.
I just wish I was aware of that rode adaptor
before i chopped off the mini on my videomic the other week :(
But as for wiring / soldering, its not my field at all.
I was going to ask a friend of mine to do it.
But all in all it seems like it could be problematic and even
if it did work I realise now that purchasing one for this purpose
wouldn't be the way to go when there are solutions already in place
for this.
The XLR-MIX™ Pro definately looks appealing.
So it seems theres not going to be a conclusive answer guys!,
cause theres no need to do it!

Thanks for the help guys.
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Old March 17th, 2008, 10:21 PM   #13
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Quote:
Originally Posted by Ger Griffin View Post
David, I never seem to be clear enough with my opening questions.

Basically ideally I would have three audio channels but only have two on my camera. These are XLR inputs.

So if i use the beachtek to take in 2 of the 3 ( 2 g2 receivers) and mix them together. Then come out of the beachtek box into one of the XLR inputs on my camera. This is why I have to change the existing minijack to an xlr plug.

Just wondering has anyone done this and what people think of this as an option instead of having to get a good portable audio mixer?
I think you have one foot on a banana peel and are about to put your full weight on it.

Regards,

Ty Ford
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