[sci.electronics] Guitar Sound Effects

jamieson@hwee.UUCP (T.S. Jamieson) (05/03/89)

	Hello,

	As part of an hobby to do with sound effects I have hit some problems
	
	This involves the actual block diagrams of the sound effects , for 

	instance I know what a Chorus pedal sounds like but I am not sure how it

	works . If any one out there has had experience with these devices and 
	
	knows how to design them could you send me the information .


	Please reply by E-mail as I am revising at the moment for my finals and

	there is little time for perusing the News .


		Thank you in advance

			Stuart Jamieson   , Only 6 exams to go !

 

wte@ncrcae.Columbia.NCR.COM (Bill Eason) (05/05/89)

In article <496@hwee.UUCP> jamieson@hwee.UUCP (T.S. Jamieson) writes:
>	Hello,
>	As part of an hobby to do with sound effects I have hit some problems
>	This involves the actual block diagrams of the sound effects , for 
>	instance I know what a Chorus pedal sounds like but I am not sure how it
>	works . If any one out there has had experience with these devices and 
>	knows how to design them could you send me the information .
>
>	Please reply by E-mail as I am revising at the moment for my finals and
>	there is little time for perusing the News .
>
>		Thank you in advance
>			Stuart Jamieson   , Only 6 exams to go !
>

I am also interested in such sound effects and think they might be of enough
general interest to post to the net.  If you don't think so, then at least
be kind enough to E-mail me a copy of replies, too.  TIA!!!

For my own questions, what are the standard impedances for "high-Z and low-Z"
audio inputs?  I know that there are matching transformers to convert from
the three-pin microphone connectors (low impedance) to 1/4" plugs (high),
but what impedances are they matching?  If I wanted to design some sort of
sound effect box, would I need to match my input impedance with some
external impedance, or would there be any problems using the textbook
op-amp principle of really high input impedance and really low output
impedance?  (I'm not talking about a passive box.)  

TIA again,
Bill

-- 

Bill Eason   (803) 791-6419    ...!ucbvax!sdcsvax!ncr-sd!ncrcae!sauron!wte
NCR Corporation		       ....!rutgers!mcnc!ece-csc!ncrcae!sauron!wte
E & M Columbia   3325 Platt Springs Rd.   West Columbia, SC  29169

eegauthe@cybaswan.UUCP (o) (05/16/89)

In article <4458@ncrcae.Columbia.NCR.COM> wte@ncrcae.Columbia.NCR.COM (Bill Eason) writes:
>
>I am also interested in such sound effects and think they might be of enough
>general interest to post to the net.  If you don't think so, then at least
>be kind enough to E-mail me a copy of replies, too.  TIA!!!

If you have a look at your local electronics shop they must have books full of
projects to build including sound effects (I bought one recently from MAPLIN
in UK but there must be some others all over the world. If you're interested
in the title just send me a mail and I will check it). The one I have include
chorus, flanger, vibrato, tremolo, parametric equaliser and an analog
synthetic drum. Everything is explained clearly (how it works and how to build
it).

>For my own questions, what are the standard impedances for "high-Z and low-Z"
>audio inputs?  I know that there are matching transformers to convert from
>the three-pin microphone connectors (low impedance) to 1/4" plugs (high),
>but what impedances are they matching?  

The 2 impedance standards are 600 ohms (low impedance) and 50kohms (high).
Actually most equipment designed for low impedance input has an impedance of
2kohms to gain some level, and a 50kohms input is 100kohms (except
transformers which match more closely to optimise the power transmission).
What you'll have to check is the type of application you have: a high
impedance will be ok for wires up to 5 feet but might give some problems for
longer ones. You won't have this problem with low impedance, especially with a
symetric low impedance link (I have description of a symetriser/desymetriser
if anyone is interested. The design is very easy).

>If I wanted to design some sort of
>sound effect box, would I need to match my input impedance with some
>external impedance, or would there be any problems using the textbook
>op-amp principle of really high input impedance and really low output
>impedance?  (I'm not talking about a passive box.)  

A compromise is designing your effect with a high impedance (which will even
be compatible with your HiFi equipment) and put a switch and a resistor if you
want to use it with a low impedance.

>Bill Eason   (803) 791-6419    ...!ucbvax!sdcsvax!ncr-sd!ncrcae!sauron!wte
>NCR Corporation		       ....!rutgers!mcnc!ece-csc!ncrcae!sauron!wte
>E & M Columbia   3325 Platt Springs Rd.   West Columbia, SC  29169


-- 
Olivier GAUTHEROT,// Postgraduate // Electrical Engineering Dept.
University of Wales // Swansea, SA2 8PP, U.K.	(+44 792 205678 ext 4564)
UUCP  : ...!ukc!pyr.swan.ac.uk!eegauthe    JANET : eegauthe@uk.ac.swan.pyr
	Usual disclaimer. Who shall I send the copyrights to?