FLANGER (weird hiss issue)

[deadastronaut]

cheers jim so a 10k trimmer from 9v to the 10k R27 then....

i,ll give that a go. cheers man. 

[anotherjim]

No, trimmer in the middle of a couple of 10k and the wiper to the cap, so you have a chain of x3 10ks in the divider but the trimmer in the middle only gives the middle 1/3rd of the adjustment range. It doesn't need to adjust to 0v or +9v but somewhere north of 4.5v but if it went as higher than 6v, you'll also lose headroom in the opamps that use the same Vb. Also, you'll get a finer control to find the sweet spot for the BBD.
By the way, did you use 5% or 1% resistors for the 10k/12k divider in the scheme? With 5%, you could be unlucky and get Vb a little out one way or the other from build to build.

[deadastronaut]

Ahh right gotya, makes sense now..

I use carbon, so yeah may have been unlucky tolerance wise...

I,ll give that a go, nice one...

[deadastronaut]

hi jim, well i tried that...

9v 10k,,,trim...10k to ground.
             wiper 
               /
               /
               /
              10uf >>>vb

its cleaned it up a little but still distorts, especially on the lower strings......hmmmm...

i used a 20k trim, and hooked up the multimeter, around 5.54 v is the cleanest, but still not there....

[anotherjim]

Just noticed there's no input filter to take ultra highs away from the BBD. Does adding a feedback cap (across R4) on the input amp help? Would be up to 330pF but not much bigger (you might just notice a 470pF) and shouldn't dull the clean signal.
Is the noise sound affected by the LFO speed or manual?
If you disconnect the wet output (lift R11) is the clean sound ok?

[deadastronaut]

cheers jim, aha, if i lift out R11 completely it seems to have cured it......yay...

no more distortion or crackle..very clean. and still flangers nicely.

i put the 330pf there anyway...


now that i have it like this, i will try my vb setup as it was, as the trimmer is a lot less fussy now..

a few more tests to do... but it think that R11 was somehow messing things up with the other R12 going back to the first opamp output...we shall see, but its a lot better already.  nice one. 

[deadastronaut]

great news, i put my vb back as per schemo, and its fine...

so the 330pf, and removing R11 works....nice and clean.

thanks jim. your a star...i can now flange my face off again. 


without the 330p the noise creeps back in. with it, its very clean.

top man...

[anotherjim]

That's just weird. Are there any solar flares near your orbit?
Unless we're looking at a different schemo, R11 has to be there or you'll get nothing from the BBD.
I don't know if R11 and R12 should cause a fight with the two opamps, but they could be 10k instead of 1k and less contentious.

[deadastronaut]

yeah i know its weird...but omitting R11 sorts it....very strange.

ive just triple checked on my breadboard and the pin 7  to R11 removed works...with it in, its back to being noisey.

the other R12 is still there, and going to the 100nf....and out...

i'm living in the twilight zone i swear it...

[DrAlx]

Unless we're looking at a different schemo, R11 has to be there or you'll get nothing from the BBD.

It can still do a flange effect without R11 if feedback (regen is used) because the delayed signal is fed back and mixed with the clean in 1C1_A.
If you miss out R11 and dont use regen, then I agree, it should not give a flange effect.

I don't know if R11 and R12 should cause a fight with the two opamps, but they could be 10k instead of 1k and less contentious.

Yeah, I would not DC couple the opamp outputs like that.
Astro, instead of clean break between Pin7 and R11, what happens if you join them with a big fat capacitor instead?
i.e. have a decoupling cap in either the R11 arm or the R12 arm.

[deadastronaut]

Cheers alex i,ll give that a go too....

Its funny i put the 1k back in there and the noise wasnt there again....lol

Im definitely in a flangey timewarp twilight zone...

But yeah as its on breadboard i will try that too....cheers guys..

[anotherjim]

Just a warning that the 330pF filter is only really right for guitar. A good use for flangers is on drums which really need full range audio to 20Khz for the cymbals, but as most adults only hear to 12Khz, you can get away with that and that would be a 150p.
By a complete coincidence, there actually is a Solar Flare warning for the next 48Hrs!

[bluebunny]

By a complete coincidence, there actually is a Solar Flare warning for the next 48Hrs!

Back in the 70s, we coped with flares for a whole decade.   

As you were...   

[duck_arse]

Just a warning that the 330pF filter is only really right for guitar. A good use for flangers is on drums which really need full range audio to 20Khz for the cymbals, but as most adults only hear to 12Khz, you can get away with that and that would be a 150p.
By a complete coincidence, there actually is a Solar Flare warning for the next 48Hrs!

is bezos shooting Capt. Kirk into the flares? will DA [the other] see him pass?

[deadastronaut]

[/quote]
Yeah, I would not DC couple the opamp outputs like that.
Astro, instead of clean break between Pin7 and R11, what happens if you join them with a big fat capacitor instead?
i.e. have a decoupling cap in either the R11 arm or the R12 arm.
[/quote]

hi alex cheers,  sorry been distracted by mrs astro stuff..again 

you mean a cap from pin 7 to r11? or a cap between r11 and r12?

[anotherjim]

Rob, each opamp "sees" the others output stage. You have a string of x2 1k resistors in between the amps so if one amp swings to +7v and the other to +2v then there is 5v/2k current flowing. That's a waste of 2.5mA current really, but in the scheme of things, it's trivial and not enough to upset the output stage of a TL0xx opamp IMHO. That said, since the following BJT boost has an input impedance a little south of 100k, those blend resistors could be 10k without dropping a serious amount of level and will, of course, reduce the wasted current in the path between the two amps quite a bit.

Why would you fit DC blocking caps? If instead of a fixed blend you had a blend pot, then any difference in DC output bias between the opamp outputs (due to offset error) could leave some DC volts across the pot. It would probably be a tiny amount but might cause the pot to crackle. You don't have a pot, so IMHO it's ok as it is.

[deadastronaut]

Okey, dokey i,ll swap the 1k' s out for 10k...cheers man.

[deadastronaut]

great, swapped the 2 x 1k's for 10k's. (R11/R12

added the 330p across the 82k (R4)

and just because i was getting a bit of break up with my high output humbucker i tamed the input a little

by swapping R1 100k to a 150k.

and all seems well....on breadboard anyway...

i will now do these mods to my pcb and put these chips into it.

and hopefully all will be well too. ...cheers guys. 

[deadastronaut]

 hi guys, flangers working lovely.....

however , and theres always a however lol......

when the 0n/off/on speed switch is in the centre ''off'', i still have a uber slow lfo going on,

instead of it being static...which is weird, i swapped out the switch in case it was faulty...

but its still slooooowwwwllly wobbling which it shouldnt at all, but it is, when it gets to the lowest point in the lfo

it collapses the flange sound and makes a strange growl noise, then stops all flanger effect...but clean sound continues...

as i say i built a couple of these, and never had this lfo 'still on' issue.....very strange. as its not connected to the 2 resistors going to pin 6 of the lfo to choose the speed. so its not connected...so how on earth is it still doing an uber slow lfo...?  weird.

[anotherjim]

Never seen a project with so many quantum distortion effects 
Wait until Haloween is over?
Sacrifice a virgin?

Maybe reverse the order of the switch and R10, R24 so the switch middle lug is going to pin6.