highway 89 shielded wire?

rpjones · July 30, 2007, 10:10:29 PM

I am gettting ready to build a veroboard Highway 89. Is this circuit high enough gain to justify using shielded wire on the input and output?
Thanks.

96ecss · July 30, 2007, 10:24:15 PM

I didn't use shielded wire with mine and it works great. I wouldn't worry about it.

Dave

col · July 31, 2007, 04:19:32 AM

I got problems with mine even when in a cast aluminium box. I know some other people have had problems as well. I cured it by grounding to the case and putting caps across the CB junctions of the transistors until it went. I got the values by trial and error, too high and you affect the tone, too low and you keep the howl. I started with 100p and went from there. This pedal has amazing sustain and a superb sound.

96ecss · July 31, 2007, 06:57:14 AM

Quote from: col on July 31, 2007, 04:19:32 AM
I got problems with mine even when in a cast aluminium box. I know some other people have had problems as well. I cured it by grounding to the case and putting caps across the CB junctions of the transistors until it went. I got the values by trial and error, too high and you affect the tone, too low and you keep the howl. I started with 100p and went from there. This pedal has amazing sustain and a superb sound.

That's interesting. I didn't have that howl even before I boxed it up.

John Lyons · July 31, 2007, 11:04:40 AM

It should be fine without shielded wire if your lead length is short.
Shielded wire will help but you may not need it.
Try it without and see how you do.

John

Ucho · July 31, 2007, 11:30:59 AM

Mine is ok without shielded wires (and they aren't even that short...), so I agree with others, you should not need them.

Semi-OT: does anybody can tell me if HW89 input impedance is "low"? I'm getting problems with a buffer, and I'm thinking if a transormer on the input (as in BazzFuss Deluxe) would help....

John Lyons · July 31, 2007, 01:16:55 PM

The input impedance is 1m as far as i can see. Although I don't know how that 22K to ground changes things.
The output impedance may be too high with that 500K pot though. It has wayy too much output gain anyway. 250K 100K log would be fine for the output pot.

John

Ucho · August 01, 2007, 05:10:07 AM

thanks for the reply John,

Quote from: John Lyons on July 31, 2007, 01:16:55 PM
The input impedance is 1m as far as i can see. Although I don't know how that 22K to ground changes things.

You're saying that because of the 1M input pulldown resistor (R1)?
I also wonder if that 22k res does something regarding the input impedance....

anyway, thanks again

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highway 89 shielded wire?