Shaka 5

[Kipper4]

Tonight breadboard experiment is the Shaka 5 (Thanks Jack @AMZ)
Its sounds good even with 2N7000 mosfet clippers.
I cant wait for the IRF520 to arrive.

Anyone built it?
Love it?
Hate it?
What's your fav mod?

Any preferred clippers etc.
I'm not mad keen on the tonestack so I might mod that.
Might just as well audition differant op amps while its on the breadboard too.

[GibsonGM]

Kipper - haven't heard it.

Any chance you could toss up a sound clip??   Looks pretty interesting! 

[th!nk]

Been playing around with an OCD sorta thing and mosfet clipping etc, not really the same but may as well throw in my 2c right?
Bought some CA3240 opamps, not all that cheap, but they sounded more pleasant than the tl072, ne5532 and opa2134 I tried - though that could just be me expecting that to be the case. They're Mosfet devices, so you have to be careful about static (not sure how that is inside the circuit, I've got another opamp in front of it with (perhaps unnecessary?) protection diodes and a resistor in front of it based on this: http://www.geofex.com/circuits/what_are_all_those_parts_for.htm). I feel like it's in the spirit of the circuit, too

Aside from that, maybe play around with series Zeners for clippers (they're kinda in a similar vein)? I think there's a page on them on AMZ, definitely some discussion around the forums (that's how I heard about it). I like 2.4V ones (the lowest I could find) but I've only played around with a few values in a couple of circuits.


Are IRF520s supposed to sound better than 2n7000s?

[Kipper4]

https://youtu.be/KqBINUl4Pik

[GibsonGM]

Thanks for the clip, Kipper!  Nice sounding OD    You could play some AC/DC with that!   Tone control seems to have quite a big range, too.   Something for everyone.

[Kipper4]

Thanks Gibbo. It is really good. I'm tempted to use the midget clipping in another experiment.
Next on the list is Joe Davidson's obsidian and a few more from Joe
Cheers
Rich

[Kipper4]

I did a couple of Jacks suggested mods sounds even better to my ears (such as they are)
increased C5 to 10nf
Increased C5 to 100nf
I'm used the unused half of the op amp as a V bias buffer

yet to try;

Increasing C2. I fear this will muddy the low end.

Other op amps to TL072


Questions guys
I noticed from the oscope that the signal is inverted does the mini -booster?
Although ive seen signals inverted in other fet stage before I got it in my tiny brain that it depended on if the signal came from the source or drain.
but i could'nt figure out a reason why it would invert in this configuration.
Can anyone tell me a little more about this mini boosters configuration?
ie its name and a bit more on how it works, blah blah blah.

Thats all for now.


Here the schematic

http://www.muzique.com/schem/shaka5.gif


Rich

[aron]

Very nice! It's been a while since I fired up my Shaka 3 - still have it. I use a lot less distortion now so will be interesting what the next "shaka" will sound like.

[Kipper4]

Thanks Think.   
I haven't tried a series Zener yet, hmmm.


When did you make your Shaka 3 Aron ?

[aron]

Looks like 1999!
http://www.diystompboxes.com/pedals/shaka3.jpg

[samhay]

>I noticed from the oscope that the signal is inverted does the mini -booster?...

The mu amp (http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm) is inverting. If that's not desirable, you could use the second op-amp to buffer and invert the output from the tone control - make a Shaka 6.

[Kipper4]

hhhhm I made a wiring mistake on the perf and I thik I fried both J201s.
I joined the blue smoke club too. My trimmer was glowing when I turned it and gave off the blue smoke.
First time I didnt use a socket Grrrr
I've replaced the Q1 jfet.
I think I'm gonna have to do Q2 too. The voltages are all wrong (compared to the breadboard)
I'm getting nearly 9v on the source.

Thanks Sam.
Mu Amp I cant get my head around it just yet. So I'll read the article a couple of times and see if i can take some in. I'll do some more reading too.
Cheers

[Cozybuilder]

Hi Rich- nice job on the clip. This one has grabbed my attention, there are a couple of builds in progress ahead of it, but hopefully it'll be on bread early next week. Thanks, and welcome to the magic smoke club.

[Kipper4]

Thanks Cozy I found the problem Q2 was back to front.
As you were.
All working now. It has a, i dont really know how to describe it but a nice sag. If thats what i mean.
I'll do some more this weekend. The three grandkids are coming for the day. Time to peel some spuds.

[Kipper4]

I'm contemplating using a Shunt regulated push pull as a replacement for the mini booster the one seen at the bottom of RG's article with noiseless biasing see here.

http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm
will this work with mpf102 2n5457 etc
looking to minimise usage of j201s at this time.


and changing the tonestack values

[mac]

I'm contemplating using a Shunt regulated push pull as a replacement for the mini booster the one seen at the bottom of RG's article with noiseless biasing see here.

Good idea. A 470k or higher from 4.5v will do it.

will this work with mpf102 2n5457 etc
looking to minimise usage of j201s at this time.

I think you need a lo Vgs fet, below a 1.5v. Some MPF102 are above 4.5v.
Try BF245A, or high gain, low Vgs 2SK117.

mac

[Kipper4]

I'll check my stock fets data sheet when I get home and breadboard it thanks Mac

[duck_arse]

kipper - k30A jfets, with a funny pinout, are usually somewhere between j201 and 2N5457 specs. very bloody cheap, too.

[Kipper4]

Thanks Duck Arse
10 on the way. I tried every type of fet i have and j201s work best in the srpp on my breadboard.
Some where less than unity.
Now I'm wondering if the srpp can be done with BJT. I searched and googled but found nothing useful.

[mac]

Now I'm wondering if the srpp can be done with BJT. I searched and googled but found nothing useful.

There is a NPN NPN Si Harmonic Percolator version, the Barge Concepts
IIRC, it's self biased with base to collector resistors.

mac