Maplin Noisegate documentation and samples

[stallik]

One of my first builds was from a Maplin kit which is now discontinued but it's a nice little device which obviously works as a Noisegate but also as an effect in its own right, softening the attack of notes at extreme settings. I'd posted pics of a rehouse I did and was asked for more info so instead of clogging up the pics thread, am starting this one.


Maplin build pdf: 
http://www.stallibrass.com/images/kas/Maplin Noisegate.pdf

Soft attack with noisegate at beginning of effects chain
https://youtu.be/DijQ91akaYo

Noise floor removal with noisegate after distortion
https://youtu.be/zqQULg-uA-4

Clean sounds and settings with noisegate after reverb
https://youtu.be/2Xi5It-kaIc

[deadastronaut]

excellent. nice one kevin..

[Mark Hammer]

I remember that one.  RG sent me a photocopy of the article (as it appeared in E&MM) way back when.  I think it was also in Electronics Today.

C4 and C10 are the rectifier averaging caps for the compress and expand.  For normal music reproduction (and magnetic tape noise-reduction), you want their actions to be identical.  By playing with their respective discharge times, you can get different outcomes.  This is what Craig Anderton did with the Rocktave Octave Divider.  Arranging the compress and expand so they were not perfectly symmetrical in their action made the divided signal shut/fade out before the signal reaching the flip-flop started to fall below triggering threshold and cause the flip-flop to sputter.

In this instance, the compressor output goes directly to the expander input.  Were they completely symmetrical in their action, this would simply get you an output just like your input (plus a tiny smidgen of added hiss).  But since the expander averaging cap can be set to discharge faster than the compressor averaging cap, it lops off the tail of what you strummed where the noise might be expected to compete with the signal.

[anotherjim]

Ah memories!
I built one of them. Does what it's supposed to do but was power hungry. IIRC, mine was in a diecast case big enough for a 9v lantern battery!
For some reason I scrapped it years ago. My bench signal generator is in that case now.

Anyone remember the volume pedal kit? A stock (Italian?) volume pedal but didn't use the pot - had a small bar magnet you glued under the pedal that worked a hall-effect sensor and a CA3080. IIRC, the CA3080 was a round can one. Never did get mine to keep a consistent control range. Can't find a scan of that one.

[Kipper4]

Nice one thanks for sharing. Good job on the pedal too.
Bonus is those NE571 chips are still available.

[deadastronaut]

+1. Ne571 on its way..

a gate and a faux slow gear in one...cool.

[deadastronaut]

okey dokey..i now have my bits to bread this..

but before i do

? why 1uf tantalums?....and will 1uf electro's be ok..?

[stallik]

Can't answer that with any authority but always wondered why the original kit came with 2 electros and the rest tantalums. There are a few close together on the original board, perhaps it was more a space issue?

[deadastronaut]

knowing maplins it might have been all they could find...


anyway, i have it on bread with signal, just need to hook up a fake rotary.. 

[deadastronaut]

well i got it going with a rotary...man you should see the leads coming off that..  

anyway, one thing that instantly needs sorting is the difference between humbuckers and single coils

for the swell stuff.. (i notice you used a strat.)

swells fine with single coils..

bugger all on hummers..   (its gonna need a switch. (use the 3rd pole i guess )

but the gate is working too..so the cap issue seems ok.

[stallik]

My strat has a JB Junior HB in the bridge position and that seems ok but I don't have a full HB to test.
I presume the pu output level will make a big difference

[deadastronaut]

yep seems it..

looking at the schemo we could do away with the rotary altogether really..

and just have 1 setting too..(setting 2) ( then just have a toggle for the hum/single coils)

i'll try it..

i have limited time today as its me and mrs astro's 20th anniversary..

so i'm off to the pub this afternoon-ish..yay!!!  

[deadastronaut]

this ...



to this...



make sense?..

[deadastronaut]

Ok, had time to try the STFU

needed an 8,2k from ic1b pin 6 to c3...voila, it works well...

and much less parts...especially the rotary....cool.

off to the pub...

[stallik]

Happy anniversary Rob. I'll have a whisky in honour of your celebration (any excuse)
R16,17,18 remain in series to ground on the original but you missed these off on the stfu. Don't know if that has a bearing on the need for the extra resistor to pin 6.
Setting 2 on the switch is normally what I use and it would be nice to do without the rotary. I think the original included it to maximise the usefulness of the circuit in different scenarios. For mere Guitarists, I'm not sure anything is lost and the swell effect certainly works better for me on setting 2

[deadastronaut]

cheers kevin, had a great night out..nice n quiet by a fire, whiskey n beer and a ban on talking pedals
from mrs astro..

anyway..

yep setting 2 is what we have now...seems ok coming straight off the 4.7uf...

i'll have a tinker about later, i was thinking it would be nice to get the gate at around 12'0clock on a pot

rather than full on/off....

and see if we can get it to clamp faster /slower too...

[stallik]

At work so can't look it up but Mark Hammer pointed out where the clamping happens on the pictures thread. Might save you some time

[deadastronaut]

cool, i'll check it out...

its in this thread..cheers mark.

[deadastronaut]

having fun with the C4/C10  compress /expand..

this clip of 3 samples is with (original schemo numbers ) ...swells nicely..(single coil pup)

C4 @ 1uf

and C10  @ 1uf....then 47uf....then 100uf...

now to get the cutoff quicker...

https://dl.dropboxusercontent.com/u/7464107/STFUTEST.mp3

[Fender3D]

Sorry guys,
isn't #1 (straight) a buffered bypass?
then why not use a 3P rotary or a on-off-on?
otherwise, you may split it in 2 potentiometers, 1st for pre gain and 2nd for out level...