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Amp Question


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You can buy a 100 watt 6-channel powered mixer for under $150US. I seriously doubt that you can build the amp part for that DIY, let alone make it quiet and reliable enough to gig with. Not all projects lend themselves to home-brewing, especially low price-point items - this is one case where you probably can't compete with the manufacturers for quality or price.

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okay, this leads me to a second question then. I've decided on an unpowered mixer and to use a seperate amp. If I just fused all 10 inputs together (5 xlrs) then split them for each out put (2 rca and 1 usb) would I have any problems or should I use capacitors for the splitting, etc. Thanks LK, your a true guru.

EDIT, oops what I meant to say was "10 inputs (5 xlrs and 5 1/4")"

Edited by silvertonessuckbutigotone
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I'm not completely sure I understand the question - when you say unpowered mixer, if you mean a standard PA-syle mixer, it should have a line output to drive the power amp, and it should be able to drive both a stereo USB line input and a monitor amp without any trouble. If you meant anything else, you'll have to explain further - BTW, an XLR connector is usually a single balanced input, not two channels.

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well, I'm actaully doing this for a freind and he's using this for recording not for gigs or live performances. He wants 5 xlr inputs, and 5 1/4" inputs, all with volume, 2 rca outputs and a USB port out, at first he wanted a powered mixer, but since I told him it wouldn't be the best quality/money ratio, he decided for unpowered. What I need to know is when I split them for the outputs, (like I said, 2 RCA and one USB) will everything still be proportionate to what he sets on the volume pots?

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What kind of mixer are you going to use? If you're planning on setting up a passive resistor summing network for 5 channels of high-impedance inputs and 5 channels of balanced low-impedance sources, you're going to be very, very

disappointed! Any decent commercial mixer will do what you need - if you're trying to roll your own, see my previous message, and add that for recording everything needs to be as quiet as possible with as wide a bandwidth as possible.

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I'm trying to build it, you said mixing the 2 would be harder to build, so I wondered if I could make 2 seperate units insyead of one.

thats

one mixer with 5 xlr inputs and 2 rca outputs and a usb port out, and a volume knob for each input.

another mixer with the same thing but 1/4" jacks instead of xlr

sorry to be so persistent, but I'm just curious.

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OK, let's block this out - at a minimum, you're going to need five (5) low-noise balanced input lo-Z preamps with input padding, five (5) low-noise hi-Z preamps (with pads), ten (10) lo-noise EQ circuits, ten (10) panpot circuits, twelve (12) high quailty faders, and two (2) low-noise gain makeup/line driver stages at a bare minimum. You're also going to need a hefty well-filtered power supply and a shielded case. My quick count shows about 40 dual opamp chips, and several hundred other resistors and caps - and that's a bare-bones mixer, with no aux or F/X busses or submixes. Keeping it studio quiet will also require a well-designed board with lots of power supply bypassing and better than average assembly skills. To top it all off, you're going to end up spending twice as much as it would cost to buy a commercial model with more features, and your homebrew will never be as quiet or as reliable! B)

If you still want to build one, PM me - I think I've got the schems for all the building blocks around here somewhere. :D

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Well, that's not all that simple, but if you only need 3 unbalanced channels, and you don't need stereo outputs, just 3 mono mixes, and you don't need channel EQ, that will work - if you try to expand it to your stated requirements, it's going to be approximately the same as what i described above minus the EQ. If you'll take a look at the page that link comes from , you'll see that he covers a lot of the same issues I mentioned earlier, including grounding and power supply regulation.

Here's an even simpler mixer:

AMZ Simple Mixer (courtesy of Jack Orman - www.muzique.com)

It also works, but it's nowhere near recording quality - you can either do it simple or you can do it right.

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