Q-Tune DIY Tuner kit

[joulupukki]

That seems like a lot of gain. And there's the DC offset on a 5v single supply R2R opamp with a single clipper. Without asking you to reveal trade secrets, are you detecting the guitar signal as variable frequency DC, essentially? Kinda a half wave rectifier via the offset and clipping?
Interesting approach if so!

We explored that direction (treating the incoming signal as a digital signal and interpreting the DC pulses in the microcontroller). In practice, we found that it actually performed much better when we still read it as an analog signal so we kept it. I spent a good number of days trying out different flavors of gain and landed on what's currently in the schematic. This being DIY, you could always use different values of resistors and experiment yourself if you felt something else would work better.

Edit: An additional challenge with treating it solely as a digital signal and counting frequency is that, with the limited number of GPIOs on this ESP32 dev board, there was no way to easily determine whether a string was being plucked or whether we were just picking up noise. We could have explored it more and added more hardware components to get that all sorted out, but ... the one analog input worked so well already.

 

[Asdrael]

. SMD would give us a lot of advantages too, then then it becomes a much harder DIY.

Make it partial SMD already soldered on and call it Notatún. We know you want to.

 

[keyth72]

This kit looks really slick! Great work in designing it. Which ESP32 dev board did you go with?

 

[Feral Feline]

... SMD would give us a lot of advantages too, then then it becomes a much harder DIY.

Given that the build is already much more complicated than most novices should/would attempt, I don't see the physical act of soldering SMD as a deterrent any more — increasingly SMD is creeping into DIY; for example via people soldering JFETs to adapter boards ( a way to get SMD practice in that's USEFUL, without "practice-boards" that have no practical end-use — that's another topic, though, don't get me started on "practice boards" oh wait I started that myself... ).

Lots of other SMD projects creeping into DIY — PedalPCB and Effects Layouts both have boards that are primarily SMD now, with MadBean and Aion both having SMD JFETs on many boards (can't recall if the latter two have fullish-SMD layouts).

The one area that would slow down sales of SMD-boards is that most DIYers don't stock SMD parts so most current SMD-projects require a special parts-order. That will change over time, but it's not pertinent here because you'll be supplying the components in the Q-Tune Kits.




While I think SMD is becoming less of a barrier to entry, I'm more than happy you've stuck with through-hole — as you've said, people can easily experiment with their Q-Tunes.






Last night's live-cast wrapped up right as I arrived at my gig, perfect timing — thanks for that!

I'm most interested in "MONITOR MODE", as I'll be using the Q-Tune with my upright.

 

[joulupukki]

This kit looks really slick! Great work in designing it. Which ESP32 dev board did you go with?

Thanks! We went with the Waveshare ESP32-S3 2.8” 240x320 with capacitive touch because it gave us a LOT better looking screen mounting option. We tried figuring out a professional-looking screen enclosure using the CYD ESP32 (Cheap Yellow Display) but couldn’t ever figure out a cover glass solution that’d be doable DIY.

Edit: We started calling the Waveshare the EBD (Expensive Blue Display).

 

[MattG]

Yes, we've been told similar things from other EE types, we've looked into it. Currently the esp32 screen we are using is GPIO limited, we don't have any more GPIOs left. So we'd have to get a GPIO extender and/or other complications. This type of thing is possible and we are interested in pursuing it, but not now, possibly down the road. SMD would give us a lot of advantages too, then then it becomes a much harder DIY.

To be clear, I was suggesting you add another microcontroller such as the ATtiny13a, and leave the ESP32 alone (i.e. ESP32 strictly for tuning, second microcontroller strictly for engage/bypass). The ATtiny13 is DIP-8 just like the NE5532. The supporting circuitry/components would have to change, but I think it would be pretty close to a wash in terms of board space (maybe even slightly smaller if you let the uc drive the relay).

 

[joulupukki]

To be clear, I was suggesting you add another microcontroller such as the ATtiny13a, and leave the ESP32 alone (i.e. ESP32 strictly for tuning, second microcontroller strictly for engage/bypass). The ATtiny13 is DIP-8 just like the NE5532. The supporting circuitry/components would have to change, but I think it would be pretty close to a wash in terms of board space (maybe even slightly smaller if you let the uc drive the relay).

Gotcha. In the long run (and now), we want the ability for the ESP32 to control the state of the relays. There are two relays in Q-Tune. One is for switching engaged/bypass and the other relay is used to switch with software between buffered bypass and true bypass. Maybe I'm misunderstanding, but if we had an external chip controlling the engaged/bypass mode, that wouldn't allow the ESP32 to control that like it does now, right?

One of the benefits we have right now with ESP32 controlling the relay states is that when you go in to settings to change between True Bypass and Buffered Bypass, the software switches the first relay to bypass mode so you can hear the difference immediately when you switch between those two options.

 

[joulupukki]

Oh, the other thing this lets us do with Q-Tune is lets you decide in the user settings which mode the tuner powers up in. You can choose to power up in bypass mode (ready-to-play) or tuning mode (muted).

 

[MattG]

Gotcha. In the long run (and now), we want the ability for the ESP32 to control the state of the relays. There are two relays in Q-Tune. One is for switching engaged/bypass and the other relay is used to switch with software between buffered bypass and true bypass. Maybe I'm misunderstanding, but if we had an external chip controlling the engaged/bypass mode, that wouldn't allow the ESP32 to control that like it does now, right?

One of the benefits we have right now with ESP32 controlling the relay states is that when you go in to settings to change between True Bypass and Buffered Bypass, the software switches the first relay to bypass mode so you can hear the difference immediately when you switch between those two options.

I may have made a bad assumption. I was presuming that you are currently using the NE555 for managing the footswitch logic and engage/bypass relay. So my thinking was that it would be minimally invasive to - loosely speaking - swap the NE555 for a microcontroller. But if the ESP32 is already involved in that to some degree, or your long-term plans are to use the ESP to control that - then indeed my suggestion makes less sense!

I was mostly just thinking out loud anyway, I've been semi-obsessed with bypass schemes for a while now.

Anyway, great project! It's nice to finally see a viable DIY tuner option.

 

[jimilee]

Given that the build is already much more complicated than most novices should/would attempt, I don't see the physical act of soldering SMD as a deterrent any more — increasingly SMD is creeping into DIY; for example via people soldering JFETs to adapter boards ( a way to get SMD practice in that's USEFUL, without "practice-boards" that have no practical end-use — that's another topic, though, don't get me started on "practice boards" oh wait I started that myself... ).

Lots of other SMD projects creeping into DIY — PedalPCB and Effects Layouts both have boards that are primarily SMD now, with MadBean and Aion both having SMD JFETs on many boards (can't recall if the latter two have fullish-SMD layouts).

The one area that would slow down sales of SMD-boards is that most DIYers don't stock SMD parts so most current SMD-projects require a special parts-order. That will change over time, but it's not pertinent here because you'll be supplying the components in the Q-Tune Kits.


View attachment 96333

While I think SMD is becoming less of a barrier to entry, I'm more than happy you've stuck with through-hole — as you've said, people can easily experiment with their Q-Tunes.






Last night's live-cast wrapped up right as I arrived at my gig, perfect timing — thanks for that!

I'm most interested in "MONITOR MODE", as I'll be using the Q-Tune with my upright.

While I have soldered SMD in various sizes, I’d rather poke my eyes with a fork than do it again for fun.

 

[Rpschultz13]

While I have soldered SMD in various sizes, I’d rather poke my eyes with a fork than do it again for fun.

Yes I agree. I’ve done just enough SMD to know I don’t enjoy it at all. SOIC-8 is fine, but just about anything else is no fun.

 

[Feral Feline]

Okay okay fair 'nough, @jimilee

As mentioned in my post you quoted, and to reiterate with emphasis added: I am more than happy the Q-Tune is through-hole.


There's no escaping SMD, though. It's here, it's part of the hobby now, and will only increase.

When all the through-hole parts supplies are obsolete and dried up...
...I'll already be through the last hole, dead for a few years, just as dead as Beta-video, steam-ships and through-hole.

 

[jimilee]

Okay okay fair 'nough, @jimilee

As mentioned in my post you quoted, and to reiterate with emphasis added: I am more than happy the Q-Tune is through-hole.


There's no escaping SMD, though. It's here, it's part of the hobby now, and will only increase.

When all the through-hole parts supplies are obsolete and dried up...
...I'll already be through the last hole, dead for a few years, just as dead as Beta-video, steam-ships and through-hole.



View attachment 96386

Oh yeah, no I wasn’t debating you, I know how much more efficient and stable smd is. We’ve been saying through hole will be obsolete for a while now. I’m not entirely convinced it will be. At least I hope not. I feel like we would lose a lot of the pedal diy community we have now.

 

[Feral Feline]

Well, there's companies like Cabintech, Xvive and CoolAudio bringing some old-tech back to life, so there's hope!
I'd like that THD remains strong, entrenched.

Lately I keep seeing yutoube-viddles titled something like "Why CDs are BACK and more important than ever"...

 

[Harry Klippton]

Lately I keep seeing yutoube-viddles titled something like "Why CDs are BACK and more important than ever"...

I keep seeing that too

 

[joulupukki]

In terms of board space, it's hard to beat SMD. Here's another recent side project I've been working on - my first design of an SMD board for a split config microphone based on the OPA Alice, I'm able to fit the body PCB of that in a standard 3/4" copper pipe that's only 3 inches long! Soldering with tweezers definitely has a bit of a learning curve but still fun and doable! In this case, the OPA1642 (the capsule impedance converter) is only available as a SMD so I was kind of already heading that direction.



At one point I thought the OPA1642 would make a good buffer IC for Q-Tune. Early this month I was experimenting with a few different ICs for the Q-Tune buffer. I tried out the OPA1642, TLV2372, OPA2134, and the TL072. To my ears the TL072 came closest to sounding transparent with the Q-Tune circuit, but when you get your kit, feel free to experiment with a different IC!

 

[jimilee]

In terms of board space, it's hard to beat SMD. Here's another recent side project I've been working on - my first design of an SMD board for a split config microphone based on the OPA Alice, I'm able to fit the body PCB of that in a standard 3/4" copper pipe that's only 3 inches long! Soldering with tweezers definitely has a bit of a learning curve but still fun and doable! In this case, the OPA1642 (the capsule impedance converter) is only available as a SMD so I was kind of already heading that direction.

View attachment 96414

At one point I thought the OPA1642 would make a good buffer IC for Q-Tune. Early this month I was experimenting with a few different ICs for the Q-Tune buffer. I tried out the OPA1642, TLV2372, OPA2134, and the TL072. To my ears the TL072 came closest to sounding transparent with the Q-Tune circuit, but when you get your kit, feel free to experiment with a different IC!

I’ll tell you what’s hard, picking up an smd with tweezers without having it flip across the room and disappear. That’s the hard part.

 

[joulupukki]

I’ll tell you what’s hard, picking up an smd with tweezers without having it flip across the room and disappear. That’s the hard part.

Haha. Totally! I was working on one mic build and thought I could add a ferrite bead next to the capsule connection and didn't realize how there are all sorts of sizes. When my order came from Mouser I was shocked. I had it on my finger tip and blinked and I'm pretty sure it evaporated into thin air!

 

[Asdrael]

Are you guys keeping preorders US only?

 

[Feral Feline]

Are you guys keeping preorders US only?

Looks that way... for the moment.

Country is greyed out and stuck on "United States".

[EDIT: Canada added!]