Script Phase 90 help with mods on Schematic

[harrisxr650]

Hi guys,

I've decided to rebuild my script phase90 clone since my 1fst one died in the hands of my 3 year old son

So i ordered a fabricated pcb since i got no time to etch one again and also is kinda dangerous with the little one wondering around.


I finished it today and sound awesome, side by side with an original script its almost identical.

So i have a couple of question regarding the mods i'm going to do.
the schematic is kinda  different from the original, probably for copyright issues, pcb is also different, more compact.

I want to add a subtle vol control, a rate led and a intensity control.

I've marked the mods on the schematic and i fast wired it to test it.

rate led: seems and works ok - i need just a confirmation i did it the right way.

Volume pot: very very subtle i didnt have a 150k pot so i used a 100k with an 100k resistor ( by mistake i wrote 50k on the schem) - is there any way to have more range on the volume? Maybe 1 250k pot with a 50k res?

Intensity mod: works fine but i'm not sure if i did it the right way.

Can someone check the schem to check the correctness of my mods?

Adding a photo of the build along with the schem.

BR
Harris

   

[antonis]

As it is,Volume pot alters Q5 gain (not volume)..

You better wire it as standar output Volume pot in place of R19..
(lug 3 on C6, wiper on Out & lug 1 to GND..)

P.S.1
How comes 710R in series with intensity pot..??

P.S.2
It is wise to short wiper & unused lug when using pots as variable resistors..

[harrisxr650]

As it is,Volume pot alters Q5 gain (not volume)..

You better wire it as standar output Volume pot in place of R19..
(lug 3 on C6, wiper on Out & lug 1 to GND..)

P.S.1
How comes 710R in series with intensity pot..??

P.S.2
It is wise to short wiper & unused lug when using pots as variable resistors..

Yeap you are right.. i've notice a small increase in gain with the vol. up. gonna try you suggestion today. Question should i keep the 50k res in series with the pot or not?

P.S.1.
i've read in tonepad that a 680ohm in series with 1M pot gives lets you control the amount of phasing signal perfectly.
And it does it pretty good.  problem was i didnt have a 680ohm  res so i wired a 560+150 ohm

P.s. 2
I guess in case the pot fails?

Thanks for the info

[antonis]

Question should i keep the 50k res in series with the pot or not?

It depends on the minimum output volume level you wish for..
e.g. 50k resistor between lug1 & GND should result into 33% where 10k sould result into 9.1% of maximum volume level..
If you worry about maintaining R19 value (150k) just use a 150k pot..
(I shouldn't bother too much about its value 'cause, although R19 participates in Q5 stage gain by placing itself in parallel with R18, its role is minor bue to particular Q5 CE amp configuration..)

I guess in case the pot fails?

You've guessed it right on the nose..

[fowl]

Do you want the volume control to go louder than normal, or only able to turn it down?  For the latter you could just replace R19 with a traditional volume pot.  150K might be hard to find, but you could use a more common value with a resistor in parallel.  With that you could go from "stock" down to zero but not louder than stock.  With the pot turned full up, it would be the same as an unmodded circuit.

For intensity control, would you be better served with a blend pot to alter the wet/dry mix?  In stock form, R15 and R16 are doing that mix for you.  It's not really the same thing, if you went "full wet" you would just have a vibrato pedal, not a more intense phaser.  Just something to consider.