Isosceles Boost noise issue with the trebble pot ccw anyone?

Abyssmal

Member
Hello, i finaly got my last piece and time to finish it this weekend, but...
Main problem is there is a nasty distortion when the trebble knob is fully counterclockwise. It disapear when i start to turn it clockwise.
Does the 1N5817 important or i can use 1n4001?
I used TC1044SCPA from tayda because before i was using one from digikey and it had a very intense oscillation noise.
Now it works better but the tri/crush switch doesnt change much the sound, or maybe i dont know what i need to hear, is it a subtle difference?
All pots values are correct.
Any ideas?

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giovanni

Well-known member
Can you take pics of the other side of the board too? What I see on this side is a lot of grime, did you soak the board in flux? Either way, clean both sides with alcohol and a toothbrush.
 

Paradox916

Well-known member
The difference between the Tri/crush (33/grind) isn’t a lot even in the actual 33 and Grind. But clean that thing up it’s pretty nasty from what I understand that can potentially cause some weird issues.

if you want more of a tonal difference between the boosts you could play with the values or R11 R12 and C14. That would definitely be something to try on a breadboard.

the 1N5817 is for polarity protection from what I understand and someone correct me if I’m wrong the 4001 won’t slam shut like the 5817 and will burn out in an inverted polarity situation, and probably fry your pedal.
 
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Abyssmal

Member
Can you take pics of the other side of the board too? What I see on this side is a lot of grime, did you soak the board in flux? Either way, clean both sides with alcohol and a toothbrush.
it's mostly just dust and a bit of flux, the picture with the big light makes it look 10 times worse, my soldering is just fine i'm used to solder 0603 or even 0402 smd.
 

Abyssmal

Member
The difference between the Tri/crush (33/grind) isn’t a lot even in the actual 33 and Grind. But clean that thing up it’s pretty nasty from what I understand that can potentially cause some weird issues.

if you want more of a tonal difference between the boosts you could play with the values or R11 R12 and C14. That would definitely be something to try on a breadboard.

the 1N5817 is for polarity protection from what I understand and someone correct me if I’m wrong the 4001 won’t slam shut like the 5817 and will burn out in an inverted polarity situation, and probably fry your pedal.

ok i'll change for a 1n5817 but like i just said in my previous reply it's the lightning that makes it 10 times worse, the soldering is just fine.
 

Abyssmal

Member
I updated the picture with one that doesnt have a 100w light straight at it so you can see it's not the soldering or build quality that cause the problem, there is something going on with the components used or something else..
 

Abyssmal

Member
I experimented this malfunction many times. Your tl071 is fake, change it and problem will be solved

oh i found tl071 from tayda in a old box here, works just fine now, no more weird noise but the tri/crush is so subtle i'm not even sure if it's actualy changing the sound or not lol
 

mnemonic

Active member
oh i found tl071 from tayda in a old box here, works just fine now, no more weird noise but the tri/crush is so subtle i'm not even sure if it's actualy changing the sound or not lol
That’s about right. When I made a Triangulum I took the parts values around the switch from the isocoles schematic and added that to the Triangulum (didn’t need the full isocoles as I already have multiple tc preamps), difference is very subtle. Slightly less treble in the ‘grind’ setting. Basically the difference between treble at 1:00 and treble at 11:00 when using the full eq mode. (And bass at 0, naturally.)

also, holy shit do people actually make fake tl071’s? Crazy.
 

Abyssmal

Member
That’s about right. When I made a Triangulum I took the parts values around the switch from the isocoles schematic and added that to the Triangulum (didn’t need the full isocoles as I already have multiple tc preamps), difference is very subtle. Slightly less treble in the ‘grind’ setting. Basically the difference between treble at 1:00 and treble at 11:00 when using the full eq mode. (And bass at 0, naturally.)

also, holy shit do people actually make fake tl071’s? Crazy.

why bass at 0 naturally?
 

Feral Feline

Well-known member
Might not be a fake TL071, but just a dud.

From experience, I know that 1 in a million sparkplugs right off the factory line are duds.
 

Abyssmal

Member
Might not be a fake TL071, but just a dud.

From experience, I know that 1 in a million sparkplugs right off the factory line are duds.
It was a tl071 from ebay, there was 10 in the package, i used them because i thought its so common chip it should be fine... but apparently not, i tried more than one in this package, all same issue. I'll never buy chips from ali or ebay in the future except if i have no other choices... and even then
 

Feral Feline

Well-known member
It was a tl071 from ebay, there was 10 in the package, i used them because i thought its so common chip it should be fine... but apparently not, i tried more than one in this package, all same issue. I'll never buy chips from ali or ebay in the future except if i have no other choices... and even then
They could all be "reclaimed" ICs from some sweatshop north of the border from here. So, may be still legit TL071s, just all dead ones! 😸

Ah well, I don't suppose they care or check if the chips are still good after burning them off whatever motherboard... doesn't matter if they're "legit" chips or not if they don't work — I just can't imagine it's worthwhile to fake 'm. There's a video somewhere on this forum of one of these reclamation sweat-shops in action, the health-code violations are appalling, let alone workers' rights...

Glad you got it sorted with the Tayda chip. 🤙
 
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