bandpass filter in a stompbox
- snk
- Resistor Ronker
Hello
Hello
I have built a stompbox version of the Roland SH5 bandpass filter.
The assembly went fine, but no sound comes out from the unit
I suspect a wrong wiring (as i suck at this, and as i think i took care to triple check every soldering, and tested every resistor and the diodes before soldering, etc), as the unit was designed to be built for a modular and not as a stompbox.
Would anyone give a look at my wiring schematic, and tell me if it is correct, please ?
The first one is the "offboard/workbench" version, and the second one is the "final" version, using a volume pot and a 3PDT, which i am planning to do once the circuit is verified and known to work.
(fwiw, at the moment, the daughter board is not installed, i am using a 15V power supply)
Thank you !
Hello
I have built a stompbox version of the Roland SH5 bandpass filter.
The assembly went fine, but no sound comes out from the unit
I suspect a wrong wiring (as i suck at this, and as i think i took care to triple check every soldering, and tested every resistor and the diodes before soldering, etc), as the unit was designed to be built for a modular and not as a stompbox.
Would anyone give a look at my wiring schematic, and tell me if it is correct, please ?
The first one is the "offboard/workbench" version, and the second one is the "final" version, using a volume pot and a 3PDT, which i am planning to do once the circuit is verified and known to work.
(fwiw, at the moment, the daughter board is not installed, i am using a 15V power supply)
Thank you !
Wiring looks fine. I'm more concerned about your power supply. This circuit calls for a bi-polar supply...hence the V+, GND and V-.
Is your 15V supply bi polar?
Is it DC or AC?
If it's unipolar then you need the daughterboard. If its AC then you need to rectify. Finally if it is indeed a bi-polar DC supply then you may very well have a problem with the build itself or an erroneous layout (but looks like it was verified by the designer)
HTH
Is your 15V supply bi polar?
Is it DC or AC?
If it's unipolar then you need the daughterboard. If its AC then you need to rectify. Finally if it is indeed a bi-polar DC supply then you may very well have a problem with the build itself or an erroneous layout (but looks like it was verified by the designer)
HTH
- snk
- Resistor Ronker
Hi,
The circuit is designed for a symmetrical 15V power supply, but said to be working with +/-12V as well.
I have both power supplies : a DC 15V bipolar ( +/-) power supply (which i used for the testing, without the daughter board), and a DC12V uniploar power supply (in this case, i will connect the daughter board to get a bipolar PSU).
The circuit is designed for a symmetrical 15V power supply, but said to be working with +/-12V as well.
I have both power supplies : a DC 15V bipolar ( +/-) power supply (which i used for the testing, without the daughter board), and a DC12V uniploar power supply (in this case, i will connect the daughter board to get a bipolar PSU).
I missed this bit...so it was working before you boxed it? In that case the problem may be something silly then. You're wiring diagram works so maybe you made an error when you were wiring it into a box, something is now shorting against the box or a wire came loose/broke when soldering in the box.
- snk
- Resistor Ronker
Hi,
No, i haven't boxed it yet : it's still out of the enclosure, and the 12V daughter board is not wired : for testing, i used a 15V power supply (as the circuit is expecting 15V, and as it is easier to spot an issue with only one single board).
My concern is that the circuit seems quite easy, there aren't a lot of components, i checked every resistor value before sodering them -as well as the diodes-, so i was somewhat hoping that it would be only a wire wired incorrectly... but it seems it's not that
No, i haven't boxed it yet : it's still out of the enclosure, and the 12V daughter board is not wired : for testing, i used a 15V power supply (as the circuit is expecting 15V, and as it is easier to spot an issue with only one single board).
My concern is that the circuit seems quite easy, there aren't a lot of components, i checked every resistor value before sodering them -as well as the diodes-, so i was somewhat hoping that it would be only a wire wired incorrectly... but it seems it's not that
- snk
- Resistor Ronker
Here are pictures of the build.
It doesn't seem too messy to me.
I noticed i forgot a 10K resistor, which was not shown as clearly as the others (it was half transparent). I added it to the circuit, but i still don' t hear anything coming through.
By looking again at the veroboard the author posted on his website, it seems there are some slight differences between his schematic and his build (
It doesn't seem too messy to me.
I noticed i forgot a 10K resistor, which was not shown as clearly as the others (it was half transparent). I added it to the circuit, but i still don' t hear anything coming through.
By looking again at the veroboard the author posted on his website, it seems there are some slight differences between his schematic and his build (
- snk
- Resistor Ronker
Thank you !Cool. I'll have a look now.
Grrr ! I just broke the red arm of my DMMcan you post voltages from all the important areas? IC pins, v+, gnd, v- etc.
I could only begin to make the measurements, so here they are for the first IC (TL072) :
from up to down, starting from the left row :
0
0
0
+15.15
right row (from up to down) :
+15.12
-13.5
+0.29
-1.08
I could only measure +15 on the upper right pin of C2, when the red arm of my DMM broke... I tried to solder an alligator clip instead, but i fear it's not that reliable anymore (i got weird jumpy values when i tried to measure IC2).
Sorry to hear! Always when you need them eh?
For future reference, IC pins are labelled as follows
1-8
2-7
3-6
4-5
...it'll make for better understanding if this convention is followed.
Is pin 4 really at +(positive) 15V? It should be at -(negative) 15V. I suspect your pins 5, 6 and 7 are off too. I've attached a a pic of your solder side (I've mirrored it to match the component side) There looks like a few solder bridges (marked in blue) and an extra cut (marked in yellow). Try looking at/fixing those (....and your multimeter lol) and let us know how you get on.
For future reference, IC pins are labelled as follows
1-8
2-7
3-6
4-5
...it'll make for better understanding if this convention is followed.
Is pin 4 really at +(positive) 15V? It should be at -(negative) 15V. I suspect your pins 5, 6 and 7 are off too. I've attached a a pic of your solder side (I've mirrored it to match the component side) There looks like a few solder bridges (marked in blue) and an extra cut (marked in yellow). Try looking at/fixing those (....and your multimeter lol) and let us know how you get on.
- Nocentelli
- Tube Twister
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Eagerly following this thread as it sounds like a great filter.
modman wrote: ↑ Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...
- snk
- Resistor Ronker
Yes, i do think soEagerly following this thread as it sounds like a great filter.
Welcome aboard !
Wonderful, thank you !I've attached a a pic of your solder side (I've mirrored it to match the component side) There looks like a few solder bridges (marked in blue) and an extra cut (marked in yellow). Try looking at/fixing those (....and your multimeter lol) and let us know how you get on.
The hole shouldn't have been there indeed : it's fixed now.
One solder bridge was in fact a marking made by my pen for spotting the holes to drill.
I have cut the other pins which might have made a solder bridge.
Sadly, I still don't get a sound (and my DMM's red cable is broken, so i can't provide any further measures)
- microbailey
- Breadboard Brother
Hi snk.
I posted a reply - but it disappeared immediately
Anyway, looking at your wiring your pots are wired up wrong.
You've got "F1 end" wired to F2 pin3, and "F2 end" wired to F1 pin 3. So they're swapped.
That's not going to work!
Also note that F1 and F2 are two parts of the same dual-ganged pot, so they change in unison.
I hope you've used a dual-gang pot for this because the filter won't operate correctly if F1 and F2 change by different amounts.
I posted a reply - but it disappeared immediately
Anyway, looking at your wiring your pots are wired up wrong.
You've got "F1 end" wired to F2 pin3, and "F2 end" wired to F1 pin 3. So they're swapped.
That's not going to work!
Also note that F1 and F2 are two parts of the same dual-ganged pot, so they change in unison.
I hope you've used a dual-gang pot for this because the filter won't operate correctly if F1 and F2 change by different amounts.
"There's something about a Gucci loafer kicking on a fuzz pedal" Alex Turner, Arctic Monkeys
- snk
- Resistor Ronker
Hi, MicroBailey
Thank you !
[edit] Ah, you mean that i have wired to F1 a wire which should have gone to F2 ? I am not sure, as from the schematic, it seems that it's supposed to be like that : from left to right : F2pin3, F1pin1, F1pin2, F2pin2, F2pin1, F1pin3... I think it's what i did (it surprised me when i was reading the layout, so i tried to stay focused when doing the wiring, eh eh), but i can try differently. Do you think it might be a mistake from the layout ?
Thank you !
That was the first time i read a pot's pin called "end", so, as a pot has 3 pins, i thought "end" meant "last" (and therefore the 3d pin)Anyway, looking at your wiring your pots are wired up wrong.
You've got "F1 end" wired to F2 pin3, and "F2 end" wired to F1 pin 3. So they're swapped.
That's not going to work!
[edit] Ah, you mean that i have wired to F1 a wire which should have gone to F2 ? I am not sure, as from the schematic, it seems that it's supposed to be like that : from left to right : F2pin3, F1pin1, F1pin2, F2pin2, F2pin1, F1pin3... I think it's what i did (it surprised me when i was reading the layout, so i tried to stay focused when doing the wiring, eh eh), but i can try differently. Do you think it might be a mistake from the layout ?
Yes, i am aware about that : i have ordered a dual ganged pot, but it hasn't arrived yet. In the meantime, i was very curious to try it that way and hear how it soundsAlso note that F1 and F2 are two parts of the same dual-ganged pot, so they change in unison.
I hope you've used a dual-gang pot for this because the filter won't operate correctly if F1 and F2 change by different amounts.
- snk
- Resistor Ronker
Ok, i soldered an alligator clip to the red cord of my DMM. I can't guarantee the readings are accurate, but hopefully it can help.
So here are the results for pins 4 & 8 (for IC1, the one on the left):
pin4 = -15.13
pin8 = +15.13
So here are the results for pins 4 & 8 (for IC1, the one on the left):
pin4 = -15.13
pin8 = +15.13
- snk
- Resistor Ronker
I made new measurements of each IC (with the alligator-clip-repaired DMM, so accuracy is not 100% guaranteed. However, i double-checked, and it gave me each time the same values) :
IC1
pin1 : -0
pin2 : -0
pin3 : -0
pin4 : -15.13
pin5 : +0.68
pin6 : -1.11
pin7 : +11.34
pin8 : +15.13
IC2
pin1 : -13.65
pin2 : +3.25
pin3 : 0
pin4 : -15.13
pin5 : 0
pin6 : 0
pin7 : +2.74
pin8 : +15.13
IC1
pin1 : -0
pin2 : -0
pin3 : -0
pin4 : -15.13
pin5 : +0.68
pin6 : -1.11
pin7 : +11.34
pin8 : +15.13
IC2
pin1 : -13.65
pin2 : +3.25
pin3 : 0
pin4 : -15.13
pin5 : 0
pin6 : 0
pin7 : +2.74
pin8 : +15.13
- microbailey
- Breadboard Brother
I was just looking at your diagram at the start of the post and it shows a wire coming from the stripboard called F1 end which is going to the pot which is called F2 (and vice versa). Based on that it looks swapped to me, but I haven't checked versus the SH-5 schematic.snk wrote: Ah, you mean that i have wired to F1 a wire which should have gone to F2 ? I am not sure, as from the schematic, it seems that it's supposed to be like that : from left to right : F2pin3, F1pin1, F1pin2, F2pin2, F2pin1, F1pin3... I think it's what i did (it surprised me when i was reading the layout, so i tried to stay focused when doing the wiring, eh eh), but i can try differently. Do you think it might be a mistake from the layout ?
"There's something about a Gucci loafer kicking on a fuzz pedal" Alex Turner, Arctic Monkeys
- microbailey
- Breadboard Brother
Those voltage readings - IC2 pin 1 at -13v doesn't sound healthy.
Pin 1 is an op-amp output (if I'm understanding the IC numbers versus the SH-5 schematic correctly) and I would expect the output to be close to mid-point of the +/- voltage rails.
Check for either a short to something on either pin 1 or pins 2 or 3 in IC2.
Also if those pot connections are swapped it might do something crazy to the op-amp inputs.
Pin 1 is an op-amp output (if I'm understanding the IC numbers versus the SH-5 schematic correctly) and I would expect the output to be close to mid-point of the +/- voltage rails.
Check for either a short to something on either pin 1 or pins 2 or 3 in IC2.
Also if those pot connections are swapped it might do something crazy to the op-amp inputs.
"There's something about a Gucci loafer kicking on a fuzz pedal" Alex Turner, Arctic Monkeys
- snk
- Resistor Ronker
Hi,
I will investigate the Opamp's pins.
I have made new measurements, and I also swapped the TL072, to check if one opamp could be faulty : it gave me the same measurements.
IC1
-0
0
0
-15.13
+0.13
-1.33
+10.88
+15.13
IC2
-13.63
+1.64
-0
-15.13
-0
-0
+1.86
+15.13
I have corrected the diagram, and this is actually the way i have wired it.
I will investigate the Opamp's pins.
I have made new measurements, and I also swapped the TL072, to check if one opamp could be faulty : it gave me the same measurements.
IC1
-0
0
0
-15.13
+0.13
-1.33
+10.88
+15.13
IC2
-13.63
+1.64
-0
-15.13
-0
-0
+1.86
+15.13
I have corrected the diagram, and this is actually the way i have wired it.