Nine ball OD

[Endosidney]

Assembled and boxed the Nine Ball yesterday. It honestly sounds great but, in at least my build, with volume all the way up and gain halfway, it’s just a smidge below unity. Is this inherent to the circuit or did I likely do something wrong

 

[jimilee]

Assembled and boxed the Nine Ball yesterday. It honestly sounds great but, in at least my build, with volume all the way up and gain halfway, it’s just a smidge below unity. Is this inherent to the circuit or did I likely do something wrong

I’m going to guess there’s a wrong value somewhere, or a small bridge.

 

[andrewsrea]

Assembled and boxed the Nine Ball yesterday. It honestly sounds great but, in at least my build, with volume all the way up and gain halfway, it’s just a smidge below unity. Is this inherent to the circuit or did I likely do something wrong

I agree with @jimilee . You should be getting plenty of volume. Check all components to the schematic from IC 3.1 to the output jack.

 

[Endosidney]

Thanks for replies. I’ve confirmed, I’m pretty sure that values past 3.1 are correct. Closely inspected under magnification there are no obvious bridges.

Has anyone put this one together that can say for certain that there should be gobs of volume on tap?

 

[Gordo]

Mine's about the same. I was kind of expecting this to be unity about half way up or so but in testing (not boxed yet) The volume is cranked and if the contour is backed off the gain has to be at least half way up.

 

[Endosidney]

Mine's about the same. I was kind of expecting this to be unity about half way up or so but in testing (not boxed yet) The volume is cranked and if the contour is backed off the gain has to be at least half way up.

That makes me feel a little better! Any thoughts on what can be modified to get some more volume?

 

[jimilee]

@Robert what say you? Any way to make it louder. Should unity be between 9 and 12?

 

[lowpitch]

Output voltage peak to peak will be limited by the combined forward voltage of D3 and D4, so with volume and tone maxed it's not going to be more than 1.4Vpp, realistically even less than that. With the volume half way up that'll only be around 0.2Vpp. Pretty low. You could change D3 and D4 to LEDs to essentially double the maximum output volume due to the higher forward voltage, but it's now going to decrease the amount of clipping in IC3.1, so the overall response of the pedal is not going to be quite the same. You could then try and increase R17 to get more gain out of IC2.2 and hit IC3.1 harder so the amount of clipping is more in line with the way it was before with the silicon diodes, but you're going to have to experiment with values and it's probably not going to be 100% the same. Might also have to reduce C14 then if it now cuts too much highs.
Another option would be turning IC3.2 from a buffer into a gain stage but then you'd have to modify the board and add resistors, but that might still be preferrable because it won't alter the response of the pedal and just increase the maximum available output volume.

 

[Endosidney]

I socketed some red leds in D3/4. Definitely more volume and a little less less gain but sounds great to my ears. I’ll experiment with R17 and report back. Thanks so much for the advice

 

[Endosidney]

I socketed some red leds in D3/4. Definitely more volume and a little less less gain but sounds great to my ears. I’ll experiment with R17 and report back. Thanks so much for the advice

Also what would be a good starting point and range for R17 values? Like 12K-20K?

 

[jwin615]

Disconnect pin 6 of IC 3 from the circuit. Either clip the socket leg or bend the pin out of the socket.
Bridge pins 6 and 7 with a resistance of 10k-470k.
The in resistance of the opamp changes with volume pot so you'll have to experiment to see what works best. Or simulate it. I'm going to be somewhere around 10k-47k will do.
A more elegant looking solution would be to cut the trace between IC3 pin 6 and 7 and bodge a resistor into the pads of 6 and 7, leaving pin 6 socketed/soldered.

 

[lowpitch]

Also what would be a good starting point and range for R17 values? Like 12K-20K?

You can go higher, 33K, 47K, 68K, see how you like it. Decrease C14 to 47p or so if it gets too dark at higher resistances.

Disconnect pin 6 of IC 3 from the circuit. Either clip the socket leg or bend the pin out of the socket.
Bridge pins 6 and 7 with a resistance of 10k-470k.
The in resistance of the opamp changes with volume pot so you'll have to experiment to see what works best. Or simulate it. I'm going to be somewhere around 10k-47k will do.
A more elegant looking solution would be to cut the trace between IC3 pin 6 and 7 and bodge a resistor into the pads of 6 and 7, leaving pin 6 socketed/soldered.

IC3.2 is non-inverting so it would need a second resistor from pin 6 to VREF for that feedback resistor to have any effect on gain.

 

[Robert]

I believe what you are experiencing is normal, even with all knobs dimed the output is just barely above unity.

ACTIVE ​

BYPASS ​

ACTIVE ​

BYPASS ​

 

[Gordo]

I read the Premier Guitar review and got the impression that this thing doesn't get very loud. I'm surprised he didn't call them out on it and it's Ted D. (the now ex-editor) doing the review. I'll have to dig up a video or two to see where their settings are.

Other than that it's a lovely sounding overdrive. I don't know that I've spent enough time with a 900 to say if it nails the sound but I quite like it.

Thanks for the response Robert. I can't believe I whiffed on using a lighted footswitch, I totally forgot...

 

[jimilee]

I believe what you are experiencing is normal, even with all knobs dimed the output is just barely above unity.

View attachment 103248

ACTIVEView attachment 103242​

BYPASSView attachment 103243​

View attachment 103247

ACTIVEView attachment 103245​

BYPASSView attachment 103246​

Thank you sir. The demos I’ve seen so far on YouTube, are way misleading.

 

[Nostradoomus]

If you boost it with a Rat, does it sound like an unfortunately quiet Morbid Angel?

 

[tcpoint]

I'm going to finish my build, today (or tomorrow). I'm going to put a switch on the d3/d4 clippers and see if that opens it up some without wrecking the tone. I'll start with double 1n4148(s) and red leds and the default diodes. Maybe a boost after the pedal is the answer.

 

[Endosidney]

I'm going to finish my build, today (or tomorrow). I'm going to put a switch on the d3/d4 clippers and see if that opens it up some without wrecking the tone. I'll start with double 1n4148(s) and red leds and the default diodes. Maybe a boost after the pedal is the answer.

Using red leds, while reducing gain a little was the trick for me. Perhaps more discerning ears could pick it apart but I wouldn’t use this pedal at its highest gain anyway. I build all pedals using a Friedman SB50 in plexi channel as my base sound. The nine ball does really sound great thru it. I play in a cover band, sorry!, and it’s nice to have a good gainy jcm900 sound at my disposal.

 

[Gordo]

Right behind you tcpoint.

 

[Robert]

Maybe I should add footprints for a couple resistors and a trimpot so that last stage can (optionally) bump the output volume up a little?

Or I suppose it could just be paired with the 3PDT output boost gadget, and I could leave the circuit alone, I reckon...