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DIY Stompboxes => Building your own stompbox => Topic started by: Melanhead on November 22, 2006, 03:12:04 PM

Title: Trying to convert low impedance/line level to E Guitar impedance and level ...
Post by: Melanhead on November 22, 2006, 03:12:04 PM
well here's the scenario ...

My band and I play most acoustic tunes but myself and the other guitar player strap on electrics for about 25% of the tunes ... He uses a GT6 to emulate some synth sounds with his electric (using the synth emulation patches, modeling technology)

We're trying to go all acoustic ( less crap to lug ) and although his acoustic ( on board preamp ) works with the gt6 it doesn't sound/track as well.

I'm trying to build a switching box that will match the levels and impedance of an electric on the input of the gt6, hoping that the COSM technology will work a bit better ...

any ideas ...

I know a buffer would work to go from high to low impedance just not sure how to do a low to high ;)
Title: Re: Trying to convert low impedance/line level to E Guitar impedance and level ...
Post by: Sir H C on November 22, 2006, 03:52:42 PM
Transformer.  Get a DI transformer and you can go hi-low or low-hi.
Title: Re: Trying to convert low impedance/line level to E Guitar impedance and level ...
Post by: Melanhead on November 22, 2006, 03:56:57 PM
it's funny but I just thought of the same thing! ... Damn, sometimes things are that simple ;)
Title: Re: Trying to convert low impedance/line level to E Guitar impedance and level .
Post by: R.G. on November 23, 2006, 12:08:38 AM
QuoteI'm trying to build a switching box that will match the levels and impedance of an electric on the input of the gt6, hoping that the COSM technology will work a bit better ...
any ideas ...
I know a buffer would work to go from high to low impedance just not sure how to do a low to high
You don't like a resistive divider?

For a divider the equivalent voltage at the output is the voltage divider output unloaded, and the source impedance is equal to the two resistors in the divider in parallel. If the divider makes the voltage be approximately 100mV peak and the divider resistor values in parallel be about 10K, you're golden. If you wanted to be really, really persnickety, you'd put a 1H inductor in series too.
Title: Re: Trying to convert low impedance/line level to E Guitar impedance and level ...
Post by: Melanhead on November 23, 2006, 09:24:38 AM
To be honest, impedance matching has always been confusing to me ... I'll give that a shot as well.

I tried a transformer last night with a 600 ohm primary and a 30k secondasy and it seemed to work like a charm! ... is 30k too high ?
Title: Re: Trying to convert low impedance/line level to E Guitar impedance and level .
Post by: Melanhead on November 23, 2006, 09:29:07 AM
Quote from: R.G. on November 23, 2006, 12:08:38 AM
QuoteI'm trying to build a switching box that will match the levels and impedance of an electric on the input of the gt6, hoping that the COSM technology will work a bit better ...
any ideas ...
I know a buffer would work to go from high to low impedance just not sure how to do a low to high
You don't like a resistive divider?

For a divider the equivalent voltage at the output is the voltage divider output unloaded, and the source impedance is equal to the two resistors in the divider in parallel. If the divider makes the voltage be approximately 100mV peak and the divider resistor values in parallel be about 10K, you're golden. If you wanted to be really, really persnickety, you'd put a 1H inductor in series too.

If I understand this: I need to measure the peak voltage of the acoustic first and then figure out what values to use for the divider to get app 100mv peak and a 10K source impedance ?