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Title: Output Impedance Question
Post by: les_chupacabra on June 08, 2004, 10:36:29 PM

So we want high impedance inputs and low impedance outputs.

Typical input impedance values seem to be from 500k to 1M (ZVex SHO = >5M)

What's considered "low" impedance? I think vintage Rats are around 1k but I've also seen pedals w/ a couple hundred ohm output impedance.

I was just looking at the Moog Phaser (http://www.moogmusic.com/detail.php?PHPSESSID=62903315da0ca4c0d97c0561fa594881&product_specs=1&modify=true&main_product_id=7&x=85&y=6) and its input impedance is 1M and output = 5000 ohm = 5k ohm.

Is that likely to cause any problems? Just stick a buffer/booster after it and call it good?

Thanks!

*******************************

AUDIO IN 1/4" phone jack - accepts any instrument-level or line-level audio signal from -16 dBm to +4 dbm. Input impedance is one megohm.

AUDIO OUT 1/4" phone jack - -4 dBm nominal output level. +8 dBm absolute maximum output level. Output impedance is 5,000 ohms.////

Title: Output Impedance Question
Post by: Eric H on June 08, 2004, 11:25:35 PM

The general "rule" is to have the input-impedance -at least- 5 times greater than the output (preferably 10 times). so in the case of the moog an input impedance of 25k would probably be adequate . You would need a buffer (DI) with many recording consoles.

Title: Output Impedance Question
Post by: brett on June 08, 2004, 11:41:04 PM

Hi.

Quoteoutput = 5000 ohm = 5k ohm

That could (maybe) be an issue for driving a fuzzface or Miss Piggy, which have about 10k of input Z. Most other pedals that I can think of have much higher input Z.

cheers

Title: Output Impedance Question
Post by: les_chupacabra on June 09, 2004, 12:05:23 AM

So what really matters is what comes next in the chain? And anything that's greater than 25k (5k*5) would be fine? Great - sounds like it shouldn't cause any problems - this would be inline w/ a couple other guitar pedals but no fuzzface (at this point) - not really at a console but that's good to know.

Thanks!

Title: Output Impedance Question
Post by: Eric H on June 09, 2004, 01:19:13 AM

Quote from: les_chupacabraSo what really matters is what comes next in the chain?

Yes

QuoteAnd anything that's greater than 25k (5k*5) would be fine? Great - sounds like it shouldn't cause any problems - this would be inline w/ a couple other guitar pedals but no fuzzface (at this point)

just put the fuzzface at the start of the chain ;)

Quote- not really at a console but that's good to know.

Older consoles generally had 2k mic inputs, a lot of newer consoles without input transformers run from 10k to 22k.

-Eric

Title: Output Impedance Question
Post by: les_chupacabra on June 09, 2004, 01:36:49 AM

Thanks for the info. Very helpful!

John

DIYstompboxes.com

DIY Stompboxes => Building your own stompbox => Topic started by: les_chupacabra on June 08, 2004, 10:36:29 PM