King of Tone Diode Question

[Guybrush]

Hi all

I'm looking at builidng one of Rullywow's Queen of Bone KoT boards and had a question about the diodes.

The build doc says I can swap out the hard to find diodes used in the original circuit and replace them with 1N914, 1N4148, red LED or BAT41 diodes. My question is do both sets of diodes (D1-6 and D7-12) have to be different types or can I just use say 1N914s for all of them?

Thanks

[GermanCdn]

You could build them up with the same diodes, but then you'd effectively have two identical circuits, and where is the fun in that?  Personally, I'd build up one side with 1N914s or 4001, and the other with LEDs or something that is tonally different.  I've got one QOB built up with 1N4148s on one side and Bat41s on the other, and on my next one, I'll change it up again, and probably put a 250 or 500 k gain pot on one side.

[Guybrush]

Of course. This makes sense.

Are you happy with the set up you have used in your finished build? If so I'll probably just go for that.

Thanks pal.

[brejna]

if you want original diodes, you can find them here http://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&cPath=2&products_id=288
Cheers

[GermanCdn]

I'm not 100% happy with my current QOB, but it's pretty good.  I built up Brian's 8-Ball using four 1N914s and two 1N4001s  with a 500kB gain pot and I'm happy with that, if only because I probably have 6 - 8 BB clones kicking around and it's got a little more oommph than the rest.

Truthfully, I prefer a clone + a BB in a stacked arrangement over two BBs side by side, regardless of the combination.  In that arrangement, I've got 1N914s on one side of the diode switch on the BB and two 3mm red LEDs on the other.

[teknoman2]

In my KOT clone I used this diodes with very good results

http://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&products_id=9

cheers,
Panos.

[rullywowr]

I agree, that having two different "flavors" on the QoB is the way to go.  This way, one will most likely be more crunchy and the other for clean boost. 

In my QoB test build, the NOS 1s1588 sound really tasty although there are a million different ones you could try.  You can hear the 1s1588 in the demo video

   

I agree, Chromesphere's store is a great place to grab these.  He has quality stuff, and reasonable prices.

Probably a great idea to socket these until you find the sound you are looking for.  Even 3mm red leds (crunchy) and some Mosfets may be tonal bliss to your ears?  I think experimenting is half the fun!

[Guybrush]

Thanks for all th ehelp guys. It is greatly appreciated.

I'm building it for a friend who wants it as close to the original spec as possible so I will be placing an order with Chroesphere for sure.

A question for you Rullywow. My friend has told me he won't ever want to run the pedal at 19vt. Am I therfore ok to leave out the TC1044SCPA or is it advisable to still include it?

Thanks.

[rullywowr]

A question for you Rullywow. My friend has told me he won't ever want to run the pedal at 19vt. Am I therfore ok to leave out the TC1044SCPA or is it advisable to still include it?
Thanks.

If he is certain he is never going to use the 18v option, then you certainly can leave out the charge pump (IC3) and D14, D15, C21, C22, C20.  I prefer it at 18v for the added clarity/headroom but I can understand those who want it as close to the original.

[Guybrush]

That's great thank you. I've been playing guitar for nearly 15 years now bit I still don't really understand what headroom means. It's a bit embarrassing but any chance you could give me a quick explanation?

[TGP39]

"Headroom", properly, means how much more clean volume you have until clipping sets in.  Hope this helps.

[mgwhit]

And when we're talking about "headroom" in this context (18V/9V op-amp distortion or overdrive) we're frequently talking about using the higher voltage to prevent (or lessen) the op-amp clipping.  In these circuits you can get clipping from both the op-amp and the diodes.  Op-amp clipping can be harsh and unappealing (unless you design for it), so using 18V or higher for the op-amp voltage can avoid that and provide a cleaner signal to the clipping diodes.

You can also use two or more clipping diodes in series or diodes with higher forward voltage to have less of the wave clipped (i.e. more headroom) in the diode clipping stages, but that has less to do with the 18V/9V discussion.

[jubal81]

I like the idea of using a diode switch to change the total Fv of the diode configuration as a 'headroom' switch. Guitar pickups vary so much in output that I think it'd be pretty useful that way.


BTW, that's an excellent demo, Rully. Pedal sounds great and the overall tone and quality of the recording are outstanding!

[rullywowr]

I like the idea of using a diode switch to change the total Fv of the diode configuration as a 'headroom' switch. Guitar pickups vary so much in output that I think it'd be pretty useful that way.


BTW, that's an excellent demo, Rully. Pedal sounds great and the overall tone and quality of the recording are outstanding!

Thanks Jubal.  Really happy how that pedal came out.  Now that I am back up and running again, trying to step up my video game as that is the best medium to show potential DIYers and pedal users how things sound.

Seeing as that one I no longer have, I have to build another QoB now...hmm now where did those 1s1588 diodes I had go?