Audio "effects path" modification for a Yamaha DJX

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iamrcb
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Audio "effects path" modification for a Yamaha DJX

Post by iamrcb » Tue Dec 20, 2011 10:54 pm

Yes, its a dodgy home keyboard with speakers, but I wanted something fun, cheap, interesting and sturdy enough to leave in the path of the (young) kids for them and me to mess with.

Is there any way which I could route the audio out of the machine, into a korg monotron or a korg mini-kp and then back into the built-in speakers, via the internal amplifier?

I assume that the amplifier is just part of some internal circuit/chip so soldering in some jacks out, and then back in may not be possible.

Could this be a possibility?

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Re: Audio "effects path" modification for a Yamaha DJX

Post by nogginj » Wed Dec 21, 2011 6:36 pm

yes it could be possible.
you'd probably just do best by soldering send/return jacks on it so you can hook up whatever youd like.
open it up, poke around, and report back.

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Re: Audio "effects path" modification for a Yamaha DJX

Post by Zamise » Thu Dec 22, 2011 12:51 am

You could also split the wires to the speakers with a switch since you are going to have to go out to external gear and back in anyway. Switch up internal, switch down external input. Some input/output jacks will switch automatically for you too, if something is plugged in then it switches to that and bypasses the route it was going like to or from the internal speakers, but you'll have to unplug if you want to switch back which may not always be as convenient as a toggle switch.
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iamrcb
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Re: Audio "effects path" modification for a Yamaha DJX

Post by iamrcb » Thu Dec 22, 2011 2:33 pm

I was thinking about routing out the speaker cables and having in/out jacks on the back, although I wasn't sure about the whole signal level thing. If i'm passing a line level signal out from the DJX into a battery powered fx unit (e.g. korg mini-kp) and then feeding that back direct into the speakers will it "drive" them? Normally the internal amp of the DJX is doing that. Does it still continue to do so even though its passed through the mini kp?

I don't mind having a switch to turn this off/on

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Re: Audio "effects path" modification for a Yamaha DJX

Post by adamstan » Thu Dec 22, 2011 3:44 pm

To do this you have to find internal amplifiers input, disconnect it from the "synth" (this may involve cutting traces) and make send-return or "insert" jack. If you want to connect external devices, you need to connect between DAC output and amplifier input.

Line output of FX unit won't be able to drive speakers, and you cannot pass "speaker-leveled" signal through it and retain its power.
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Re: Audio "effects path" modification for a Yamaha DJX

Post by Stab Frenzy » Thu Dec 22, 2011 3:58 pm

adamstan wrote:To do this you have to find internal amplifiers input, disconnect it from the "synth" (this may involve cutting traces) and make send-return or "insert" jack. If you want to connect external devices, you need to connect between DAC output and amplifier input.

Line output of FX unit won't be able to drive speakers, and you cannot pass "speaker-leveled" signal through it and retain its power.
This is pretty much what I was going to say, with the addition of running the speaker output into an effects unit will at best be horribly distorted and at worst destroy the effect.

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Re: Audio "effects path" modification for a Yamaha DJX

Post by rhino » Thu Dec 22, 2011 6:22 pm

Just a thought: Locate the volume slider, make sure it's audio not DC control, and cut the trace to the top end (many samll Yams use printed pots on the boards) run the feed to the "out" jack. Run the "in" jack back to the top of the pot. The synth may well be stereo, so you may need to combine the L and R sides with resistors.
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