Sparkle Drive adaptation

[Kipper4]

I'm thinking this one should be on the build list but i dont have the bjt ne5532n Ic
I might have some on order but I'd like to make it with common jfet ics
how do I rebias the circuit for a TL072 in the later stage.

heres the layout

http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/SparkleDrive_LAYOUT.gif.html

heres the schemo

http://home.kpn.nl/chrisdus/download/VLSD.jpg

I believe they are the same. I havent double checked yet.

I'd appreciate the input and ideas please.
Probably about time this idea was bought upto date
Thanks
Rich

[Kipper4]

I've had a quick look at the schemo and i'm no expert.
Is there a good reason why i couldnt build a clean part of the circuit using an Tl072 mild boost and use a single pot in the place of the 100k clean pot (dual in the schemo) to simply blend the gain stage with the clean stage?
Or would i need some sort of rudimentary splitter/mixer to achieve this?

[Kipper4]

My guess is that the mpsa stage is an iput buffer.
could i use a dual gang 20k pot (what i have in stock)in the place of the 100k dual.
This has to be the splitter (reunification) section of the two stages.
Put me right if i'm way off guys.
thanks
Rich

[samhay]

NPN is an input buffer.
It will almost certainly work with a TL072 as is.
It will probably work just fine with a dual-gang 20k pot, but you might want to breadboard it to be certain.

[Kipper4]

I'll breadboard it some time this week
Thanks for the help and clarification.
Cheers
Rich

[pinkjimiphoton]

rich, in  dirt box, pretty much any dualie opamp = any dualie opamp. it will work, tho some may sound better than others.

[Kipper4]

Thanks Jimi
This is next up on the breadboard.

[Kipper4]

I built the Sparkle today and used a 20k dual for the Blend pot and it works fine
I've yet to thouroughly test it but initial tests sound promising.
I really like the blend choice and am now seriously thinking of making a similar build with a SOS distortion front end with mosfet clippers in the feedback loop.
I Intend to use JRC4458's for both op amp stages.
Maybe even use a TL074 (qaud) and see if i can keep the footprint down further.
Any help is appreciated.
Back to the drawing board  !!!!!!!!
Rich

[Kipper4]

Guys question.
How do I make the son of screamer distortion stage have more mid hump please?
Change the cap in the feedback loop?
Implement a high cut filter and a low cut filter somewhere in the distortion stage?
If so where and what caps would you recommend?
I would like to use this pedal with my Fender pro junior which by it's very nature is a bright amp. So I think it would sound good with a nice blues tone in the distortion and keep the clean fairly neutral.
I'd appreciate your opinions on this too.
If you think it would sound c.r.a.p just say.

[bluebunny]

The madbean take on the TS has a "bright" switch, which cuts the mid-hump by removing that 220nF cap to ground, right by the tone pot.  Seems to be a similar arrangement in the Sparkle.  I guess if you want to increase the mid-hump, this is where you should play?

[Kipper4]

Thanks mark I'll think about it and have a play.