BSIAB2 squealing.

[Hupla]

Hey guys. I just finished Building the BSIAB2 using this Vero layout, http://www.diystompboxes.com/smfforum/index.php?topic=79288.0, And I know that that link is basically about the same thing but for me this didnt squeal on the breadboard, only when I put the tone up the whole way, but now it squeals all the time.

I have got it to not squeal though, by using all 2n5457's and by putting the trimmer to around 7.6v. (although this works with having the j201's in also) This sound is ok, but I just find myself wanting to solve this problem.

Should I try etch Gaussmarkovs pcb layout and use that instead? I don't really feel like taking mine all apart so I may do that another time.

I don't have the input shielded and it is right beside the output at the switch. Should I change this?

I plan on making the Dr. Boogey next so I want to implement what Ive learned here into that also, to prevent squealing from the start.

Also, I find the tone to just boost treble when turned clockwise and then get rid of it when turned left but not boost the bass resulting in volume loss. Is this very common?

All in all Im rather pleased with it and its usable, I just want to learn about this more than anything, so thanks in advance.

[shadowmaster]

Here are some of my observations. I hope it helps.

1) I find that high-gain circuits squeals more on breadboard than on PCB build unless the latter is very badly designed.

2) I find that biasing around halfway the supply voltage in BSIAB2 always produces the best sound. Although it is also the noisiest setting, I believe that this can always be tamed with good layout, good wiring and good shielding considerations.

3) I find that the BSIAB2 squeals with a bad power supply. BSIAB2 works best with regulated and well filtered power supply.

4) I find that it is better to box-up (aluminumum or metal) your build before considering using shielded wires for your input and output. My BSIAB2 and Dr. Boogey squealed like hell during my tests before boxing them up. Once they were inside their respective enclosures, they kept quiet and I became a happy man.

5) I find that my Dr. Boogey is more behaved compared to my BSIAB2. My BSIAB2 has a tolerable but noticeable hum.

6) I find that BSIAB2 is designed as a distortion that put emphasis on highs and little on the bottom.

[fpaul]

I buiilt 2 using the GGG layout with no squealing at all even with the gain up.  And they both have LOTS of gain.  I didn't use shielded wires and my wiring wasn't particularly neat.  So I'd recommend that layout.  Haven't tried Guassmarkov's tho.

[DUY1337GUITAR]

have you checked for any slight possibility of a ground loop? I've built two Dr. Boogeys, and you can hear a faint squeal on the first one.  When bypassed and switched to the distortion channel on my amp, it screeches like crazy.  But on my second Dr. Boogey that I made for a buyer, I pretty much semi-star grounded and there was absolutely no squeal or noise.  It doesn't make noise when i bypass it and switch to distortion on my amp either. 

Also, it could also be that you have one or two bad transistors.  I know this is sometimes the case with J201's but I'm not sure about the 2N5457's

I hope you can get this fixed, good luck!

[Hupla]

have you checked for any slight possibility of a ground loop? I've built two Dr. Boogeys, and you can hear a faint squeal on the first one.  When bypassed and switched to the distortion channel on my amp, it screeches like crazy.  But on my second Dr. Boogey that I made for a buyer, I pretty much semi-star grounded and there was absolutely no squeal or noise.  It doesn't make noise when i bypass it and switch to distortion on my amp either. 

Also, it could also be that you have one or two bad transistors.  I know this is sometimes the case with J201's but I'm not sure about the 2N5457's

I hope you can get this fixed, good luck!

Thanks for all the replies guys. Im going to get it all put into the enclosure first and see how it sounds then, and then i will mod it with your suggestions.

I love this forum for replies

[Ed G.]

I'd use some shielded cable for the input. I have a pedal that squeals a bit at max gain and when I moved the input wire around it went away. Ground the shield at one end only.

[Hupla]

I'd use some shielded cable for the input. I have a pedal that squeals a bit at max gain and when I moved the input wire around it went away. Ground the shield at one end only.

Thats one thing i was always confused about. I would of thought you would have to ground at both sides

[Bucksears]

I'd use some shielded cable for the input. I have a pedal that squeals a bit at max gain and when I moved the input wire around it went away. Ground the shield at one end only.

Is that shielded for the input jack to the switch, or the switch to the input on the board?

Thanks,
- Buck

[Hupla]

Good news guys. Its in the enclosure now and there is NO squealing at all. Only eventual feed back when i turn everything up. so BRILLIANT news.

But I still think everything you guys have said is worth knowing and keeping in mind so thanks

[DUY1337GUITAR]

Good to hear  Glad it's now working, gotta love the feeling of successfully finishing a challenge.

Right now I'm stuck between spending my birthday money from new year's on a BSIAB2 or a new Dr. Boogey or a Pepper Shredder or a Metal Simplex or another pedal or another pedal or another pedal or.... I'm guessing this is another challenge to get through...

[liquids]

Good to hear  Glad it's now working, gotta love the feeling of successfully finishing a challenge.

Right now I'm stuck between spending my birthday money from new year's on a BSIAB2 or a new Dr. Boogey or a Pepper Shredder or a Metal Simplex or another pedal or another pedal or another pedal or.... I'm guessing this is another challenge to get through...

[Hupla]

Well bad news. Brought it to practice and it started squealing again. Had to roll the volume on my guitar off a tiny bit to get rid of it. Any ideas?

[DUY1337GUITAR]

that sounds like a grounding problem to me
Do you still hear a squeal, at least faintly, when you bypass the BSIAB2?  When the pedal is off and you switch to the distortion channel of your amp, does it make noise that shouldn't be there?
I hope we get a pro in here to help, too.  High gain pedals are hard to deal with.

[Hupla]

Im pretty sure I didnt hear it when it was bypasses but i cant give u a definite answer right now. What sort of grounding problem do you mean?

[DUY1337GUITAR]

what I meant by grounding problem was possibly a ground loop.  it could also be the placement of your components because it can cause oscillations since this is a high gain pedal we're looking at. Shielded wiring from the input jack to the stompswitch to the circuit board is recommended so the ground connection that wraps around the "hot" wire will prevent signal to interfere with it. 

[Hupla]

Yeah I understand how the shielding works im just confused about what exactly the ground loop problem could be. I wonder has it got anything to do with how at home I had it as the only pedal in the chain being powered by the Power supply , but at practice its power supply was daisy chained with other pedals?

[DUY1337GUITAR]

I meant the grounding problem could've been in the wiring of your BSIAB2.  But I think it might be oscillations that occur due to the layout of your components.  For example, the circuit board is placed right over the potentiometers, the input jack is close to the output of the circuit board, the output jack or volume pot is too close to the input of the circuit board.  When you placed everything in the enclosure, the oscillations were probably relieved somewhat.  These problems should be watched out on high gain pedals, but if they aren't the cause then I don't know what else

[Hupla]

I tired to overcome these a bit with my design but it just didnt really work out in the end cause it was squeezed into a 1590b

heres the guts anyway

The input is the lower edge of the board.

I just cant understand how it changed from at my room to practice =/

[liquids]

Well bad news. Brought it to practice and it started squealing again. Had to roll the volume on my guitar off a tiny bit to get rid of it. Any ideas?

That means that reducing gain/increasing resistance 'fixed' it....

I just cant understand how it changed from at my room to practice =/

New room, new acoustics, new resonant frequencies, new volume, guitar is a new distance from amp, and plenty of other variables.


 
Keep in mind that BSIAB squeal has been posted about here...hopefully you have (or will) search the forum for similar inquiries that might be enlightening...

In some manner, you might want to add a high input impedance inverting buffer stage at the beginning or end of the circuit, that you can switch that in or out. and compare to what you have right now.   Switch it on and see if that is the issue, as sometimes phase has a factor in squealing, etc.

Honestly, J201s are, IMO, overrated.  Unnecessary gain, low dynamics, lacking in tone.  Possibly far more prone to oscillation due to their being so unique in their 'gain levels' to put it technically.  

 2N5457s aren't that much 'lower gain' typically, to me, in this circuit, however they seem to make a difference for those with these kind of issues.    Are you using it with the gain full up? And If not, put in 2N5457s back - better tone, less prone to squealing, less headaches for you until you can get better understanding of the cause of the squealing.   And If so, maybe it's the wrong design for you, as most people find it mush city when built stock and the gain is cranked up.     Even Ed G. says similar--mostly to avoid the J201s, these days, on some posts and PMs of his I've read if I'm not mistaken...

I'm a big fan of lower gain MPF102s / 2N5459s and higher value emitter resistors around for Q1-Q4, but I've documented a lot about my preferred mods elsewhere, so search my posts if you're interested, but they're not for everyone...back to my main point, stock, that thing has plenty of usable gain, and quite a bit of unusable gain if you ask me.

Beyond reducing gain, I'm a fan of making C10 more like 4.7n, so there is less mid scoop.  However, if you like the tone, that may not be the mod for you.  But try it on the breadboard and see....you might be surprised.  That tone stack as is passive, but exaggerates bass most of all, which may somehow induce feedback, depending on your other equipment and settings, though the rest of the circuit is rather' tight' in the bass.  That one mod makes it more even and midrangey, and helps take the tone pot 'off' the mids and focus on the highs more.  

Still, It's hard to know what kind of 'squeal' you mean, which makes it hard to advise too much outside of the generic...Got any soundclips?    Kidding mostly...

Also, it comes down to 'What PS?' and 'How did you wire the stomp switch?' etc. It could be that you are using a cheap guitar with unpotted and or cheap pickups, for all we know, which would easily squeal with the amounts of gain the BSIAB puts out. There are just too many variables, so it may be better left to your careful inspection and experimentation...isolate / eliminate some of these variables that it may be, one by one, after these rounds of attempted quick fixes...that may be better than everyone continuing to detail every hypothetical possibility and thing to double check.  Change guitars, change rooms, change underwear...isolate the variables.   It's fun.  

[DUY1337GUITAR]

Oh, I was about to ask for a gut shot, too. 
You didn't wire the ground lugs on both jacks to the ground, right?  I'm just making sure because I can't tell from the picture, all the wiring is covering up the lugs haha.  And is that the input side or the output side of the circuit board that's hovering over the potentiometers?