Sparkle Boost build report

[andrew_k]

I've been on a bit of a boost hunt. What I'm looking for is a essentially a 'lead break' pedal, something that cuts through the mix but is still suitable for subtle stuff; ie: jazz. One of the requirements I had is that it must be a small circuit; something that will fit in a 1590A enclosure.
I've built or breadboarded the following:
- AMZ mosfet boost
- SHO
- LPB
- various simple JFET boosts
- NPN Rangemaster (using tested NPN germ from smallbear)
- Dragonfly's Sparkle Boost.

MOSFET boosts didn't seem to like my gear. The SHO and AMZ mosfet boost were both quite hissy with my vibrochamp. Both were nice, just not quite suitable for me. The LPB was the exact opposite of what I'm looking for. Dark, lifeless.

The Rangemaster was nice and I'll probably box one up, but it's not suitable for the roll as my primary boost. Not enough volume for starters. Guitar > rangemaster > amp sounds gritty and Rock, but it's too shrill for some stuff that I play and completely destroys the depth of low notes; which is to be expected of a treble booster.

The JFET (j201) circuits I tried lacked the hiss of mosfets and closer to what I was after. Then came the Sparkle Boost.

Schematic - http://www.freewebs.com/soulkitchen/SPARKLE_BOOST_SCHEMATIC.JPG

Even on the noisy breadboard I could hear that this circuit suited my needs well. After increasing the input cap to 0.047µF, I got what I was looking for. Clean boost with a touch of grit in the treble (i replaced the gain pot with a 2.2k resistor), lots of boost on tap (unity seems to be at about 4). Helps punch above the 15th fret without losing too much down low. The finished pedal is dead SILENT; no hum at all and absolutely no switch pop thanks to the 2.2M pulldown resistor.

Here's the finished unit:


If anyone else with similar requirements to me is looking for a boost, I definitely recommend giving the sparkle boost a try.
Thanks for the design Dragonfly 

[John Lyons]

Nice looking build and report.
Which hammertone color/brand is that?
There are so many colors that are actually made that the stores just don't stock.

John

[andrew_k]

Thanks John
The enclosure is a pre-painted one from pedalpartsplus, I don't know the name of the paint unfortunately.
They do a good job, definitely worth it for people like me who live in tiny city apartments and can't break out the airbrush!

[rogeryu_ph]

I'll breadboard this too.... My AMZ mosfet has lot of hiss whenever I turn mid my 65w AMP volume
I did try replacing the 10meg into 1meg it's still the same. I did breadboard the SHO its also noisy when turning up the AMP volume. Many had said thier AMZ mosfet has no hiss maybe they haven't tried loud setup or unaware when they volume up the amp don't know
BTW nice built.

Thanks Andrew,
Roger

[ConanB]

Thanks John
The enclosure is a pre-painted one from pedalpartsplus, I don't know the name of the paint unfortunately.
They do a good job, definitely worth it for people like me who live in tiny city apartments and can't break out the airbrush!

I whipped out the ol spray can in a cupboard with a bunch of cardboard to protect the place. Worked well, made sure all windows were open.
If only I could get a place with a garage without moving further out of the city

Nice looking build!

[Renegadrian]

I had all the components in my bin, so I said "HEY LET'S BUILD IT!!!" 
I built it today on vero (torchy layout) with only the GAIN pot wired, trying both J201 and 2N5457 - they both work good, altough the trimmer here is so important.
J201 -------> trimmer at his middle
2N5457 --> trimmer at low value, slightly open...

Another simple circuit with a GREAT sound...I like it so much! THX Andy for the SPARKLE BOOST!!! 

[Dragonfly]

I had all the components in my bin, so I said "HEY LET'S BUILD IT!!!" 
I built it today on vero (torchy layout) with only the GAIN pot wired, trying both J201 and 2N5457 - they both work good, altough the trimmer here is so important.
J201 -------> trimmer at his middle
2N5457 --> trimmer at low value, slightly open...

Another simple circuit with a GREAT sound...I like it so much! THX Andy for the SPARKLE BOOST!!! 

Its one of my favorites...I'm glad you dig it !

[ubersam]

...Here's the finished unit:
http://notinteractive.com/stuff/guitar/fx/sparkleboost.jpg

Very nice compact build :thumbs up: what size box is that?

[Dragonfly]

I had all the components in my bin, so I said "HEY LET'S BUILD IT!!!" 
I built it today on vero (torchy layout) with only the GAIN pot wired, trying both J201 and 2N5457 - they both work good, altough the trimmer here is so important.
J201 -------> trimmer at his middle
2N5457 --> trimmer at low value, slightly open...

Another simple circuit with a GREAT sound...I like it so much! THX Andy for the SPARKLE BOOST!!! 

Hows it sound pushing the Valvecaster ?

[Renegadrian]

Hows it sound pushing the Valvecaster ?

Had a try...Well, the two togheter SCREAM!!! it's HEAVY METAL!!!
I run the SB with the 2n5457 in, then my toneless Valvy with vol and gain set at something less than the max.
The SB is a good companion, expecially on solos - high notes are well defined even at its max gain.
You may want to tweak the amp highs, as to get the best results on the E or A string palm muted riffs...
That said both at min and max gain.

[Dragonfly]

Hows it sound pushing the Valvecaster ?

Had a try...Well, the two togheter SCREAM!!! it's HEAVY METAL!!!
I run the SB with the 2n5457 in, then my toneless Valvy with vol and gain set at something less than the max.
The SB is a good companion, expecially on solos - high notes are well defined even at its max gain.
You may want to tweak the amp highs, as to get the best results on the E or A string palm muted riffs...
That said both at min and max gain.

sweet !