GGG Phase 90 speed?

[Butcher]

Hi all,

I built a GGG phase 90 and all works well but I can't get the speed as slow as I would like. It is faster than MXR ones that I have heard. The BOM calls for a 500k Reverse Log Taper pot or 100k linear. Kit came with the 100k. Would the 500k be slower than the 100k?
If not what would work to slow it down?

Thanks in advance,
Dave

[duck_arse]

the 500k will extend the speed slower, yes. if your C7 cap is 15uF, you can tack another electro across it to slow down the 100k pot. try 4u7 or 10uF.

[Mark Hammer]

The duck is spot on.  The speed is a function of the combination of the 15uf cap and the resistance that governs how fast it can charge up.  The fastest it can charge up is set by the 4k7 resistor, and the 500k pot adds more resistance on top of that.  At the fast end, it doesn't take much change in resistance to yield an audible change in speed.  At the slower end it takes much more resistance to produce an audible change.  This is why reverse-log , or C-taper, pots are generally preferred for speed/rate.

What this suggests is that a 1M reverse-log pot would be recommended to achieve what you want.  If you don't have one, but DO have a regular log pot, just wire it in reverse, so that clockwise is slower.  You can also increase the cap value, as duck suggests.  Or you can use a toggle and a resistor in series, like 330k-470k, to switch between ranges, without having to get another pot.

[Butcher]

Great info!!
Thanks guys.

[Butcher]

Thanks guys,
I have added a 10uf cap to C6 and that has slowed it down some but would like to go a little more. With the stock 15uf and adding the 10uf brings me to 25uf correct? I could go with a single 47uf to get slower or If I add resistors to a switch where do I add them?

Thanks again,
Dave

[Butcher]

Anything?

[duck_arse]

I thort we'd fixxed this.

what value pots do you have? if 10uF added is not slow enuff, try another 15uF if you have it, or a 22uF. or pull the 15uF and replace with a 33uf or a 47uF. what values electros do you have?

[Butcher]

I thort we'd fixxed this.

what value pots do you have? if 10uF added is not slow enuff, try another 15uF if you have it, or a 22uF. or pull the 15uF and replace with a 33uf or a 47uF. what values electros do you have?

Thanks Duck,
Well since I have been pulling components out of every piece of junk electronics I can get my hands on I have a variety to choose from. I will try a 47uF
Does anyone else find it relaxing to pull parts off of old boards?

[Mark Hammer]

It is neither relaxing, nor cost-effective.  But I do get fed up with creating yet more e-waste, so I'm willing to investthe frustration and time to cut back on my share of e-waste.

[Butcher]

Maybe it's just me then. Lol