Anyone tested the SHO PCB from tayda?

[Will.mendil]

Hi,

I ordered and assembled the super hard on from tayda and it sounds terrible. The hiss is monstrous and the pot kills the sound when turned until the caps "refill". I was just curious if it was my own doing, one of the parts that is broken or if the circuit is just rubbish.

Cheers

[pinkjimiphoton]

Hi,

I ordered and assembled the super hard on from tayda and it sounds terrible. The hiss is monstrous and the pot kills the sound when turned until the caps "refill". I was just curious if it was my own doing, one of the parts that is broken or if the circuit is just rubbish.

Cheers

i'd looked at that thing, looked ok to me, but haven't built one of them.

in the sho's i've built tho, they're pretty hissy depending on the fet you use. if the pot is killing the thing, i'd suspect there's a solder bridge somewhere. not much TO a sho to go wrong, but the semis are fairly easy to damage... and damaged jfets (if they work at all) often seem to be really hissy.

ymmv, so...

[Will.mendil]

Hi. I have fixed the hiss by filtering the dc. Though knob still kills the sound unless I turn it very slowly. The pedal distorts when put to max which I expect to be normal. I've tried bread boarding with new components and it acts exactly the same. So unless all the trans I have are broken then it must be how it works. But does not seam to be in videos I ve seen.

Fiy I am using the two diode version.

[Will.mendil]

I do not have any Zener to try the newer version

[gjcamann]

You may want to try this one - I think it's $5 shipped for 3 boards. It's made by a guy over at madbean.
http://www.oshpark.com/shared_projects/nsJTeQK0

[Tony Forestiere]

Crackle Okay? http://www.thegearpage.net/board/archive/index.php/t-658923.html

[pinkjimiphoton]

yeah, it crapping out while ya turn the knob is totally normal. that's why it says "crackle ok"...

the diodes aren't in the audio path, or shouldn't be. they are only there to protect the fet.

is the casing of the pot grounded? are all the ground points connected to a star ground?

you're almost describing what happens when a ground is lifted somewhere. i would check them diodes.
d1 may be changing your bias by dropping too much voltage, depending on what kind/model diode used.

a ge diode will drop about .30 v,  silicon maybe .70 or more. fets of all kinds are notoriously fickle about bias.

fwiw, the SHO's i've built didn't have all the extras in them, are so loud i need to add volume controls to the arse end, and are very CLEAN when all the way up.... not distorted... also making me suspect the bias is wrong.

wonder if maybe one of them diodes got overheated and is leaking or something....?

[PRR]

Boil a BIG pot of pasta. (Get the air humid.)

Disconnect one end of each diode. Does it still knock-out?

[pinkjimiphoton]

Boil a BIG pot of pasta. (Get the air humid.)

Disconnect one end of each diode. Does it still knock-out?

curiosity piqued...... disconnecting one end of each diode i understand, but why the humidity?  to see if it arcs or something?

please enlighten my far from smart posterior paul!!!

[PRR]

When air is damp, it is semi-safe to leave MOSFET gates un-protected.

When the heater is running constant (it got cold here today) and drying-out the air, your body can build up thousands of volts of static charge.

There's also cases where gate gets connected to something large and static-charged like a guitar amp or even "ground".

So we "need" the diodes generally. But a quick bench-test can be done without diodes IF the air is humid.

[haveyouseenhim]

Probably the only perk of living in south Alabama 

[Will.mendil]

Well I used 1n4148 diods if I am not mistaken. You will get the exact components from tayda a website. The SHO in the PCB guide.

I tried with difference component. Same result. I ve filtered the donc and there is still hiss . How do I check the bias? Maybe the resistor values are not the best. Are they?

I ve even brought all the grounds together and it is exactly the same. I can't really figure out what the problème can be especial if you say that the schematic is right

[pinkjimiphoton]

When air is damp, it is semi-safe to leave MOSFET gates un-protected.

When the heater is running constant (it got cold here today) and drying-out the air, your body can build up thousands of volts of static charge.

There's also cases where gate gets connected to something large and static-charged like a guitar amp or even "ground".

So we "need" the diodes generally. But a quick bench-test can be done without diodes IF the air is humid.

i totally get it... thanks for the explanation paul!!

@Mike.... amen dude.... up here in yankeeland, this is the time of year to REALLY "let the smoke out" of things.

[Les Paul Lover]

fwiw, the SHO's i've built didn't have all the extras in them, are so loud i need to add volume controls to the arse end, and are very CLEAN when all the way up.... not distorted... also making me suspect the bias is wrong.

wonder if maybe one of them diodes got overheated and is leaking or something....?

I've built the same clone as the OP but with a PCB from Pedal Parts UK, and there's quite a bit of dirt on tap with that pedal.
Obviously quite a lot of volume boost too, but it gets as dirty as a couple of gain stages i'd say.

FWIW, i've only tried it with my AD15 so far, admittedly not an amp with a great amount of headroom - but even with volume at 8 o'clock & gain at 9 o'clock (clean/not loud) there will be dirt.

I like it!

[Les Paul Lover]

I hope this can help solve your problem – I've built a SHO clone with this kit:

http://pedalparts.co.uk/wp-content/uploads/2012/10/Boner.pdf

When I 1st built it, I daamaged the pot solder joint after the 1st test - leading me to try to resolder everything and fry the transistor BS170 in the process.
Below are the voltge reading I had with the BS170 fried - I'm afraid I haven't got updated Vs after swapping the BS170, but could provide it if of assistance.

R1
6.2v
0v

R2
6.2v
6.2v

R3
9.5v
6.2v


R4
0v
0v

D1
9.5v
6.2v

D2
0v
6.2v

C1
6.2v
0v

C2
6.2v
0v

Q1
3.1v
6.2v
6.2v

[Will.mendil]

Cool. Well test that tonight. Unless the two trans I've tried are fried it is a recurring problem. Moreover I use a transistor amp and it distorts as well. I am not sure if it the amp the distorts or the pedal. I am getting parts for building a murder one. I'll try and see how it behaves when I finish it. Which won't be soon.
Maybe someone could send a working SHO voltages for comparison. Cheers

[duck_arse]

over at amz, or maybe geofex, says you can trimpot the bias with a single resistor to gate, to get the bias "right". does the drain bias (for want of a better term) method auto-correct, or is this a potential "sounds bad/doesn't work" pinch point?

[Will.mendil]

Would you have a diagram of this "hack"? I don't really understand what resistor to put as there's already one bridging two legs of the transistor

[Will.mendil]

I got 5V on D, 2,32V on G and 0,05V on S. and i am running off 9.58V, does this sound right to you?

[Les Paul Lover]

I'll start assembling my reverb pedal kit tonight, so I'll get the SHO circuit out and remeasure it for you.

I'll update you tonight or more likely tomorrow.