Converting guitar/bass line signal to USB?

[Steve973]

I've searched a bit, and for all of the products that are available on the web, from boxes like the Scarlet and the PreSonus to smaller things like the iRig and even some really cheap cables, I am really surprised that I don't see much talk about converting line-level guitar and bass signals to USB. I am building an effects loop box with an XLR out (in addition to 1/4" phono), and I was thinking that it would be cool to have a USB out, as well. How difficult would it be? I imagine it would be some A/D converter, and then a USB codec. But, beyond that, I do not know how to design circuits!

Of course, I'd love to buy a PedalPCB module for such a thing, which is why I am posting this in the Wish List forum. In the meantime, and if I don't get many votes, would any of you be kind enough to point me in the right direction, please?

 

[giovanni]

I think it’s gonna be more practical to buy an audio interface. You could try looking into the Daisy Seed to see if you can get the same result but at that price point you might as well go for the interface.

 

[Steve973]

I think it’s gonna be more practical to buy an audio interface.

I am sure it would be. I mean, I already have a PreSonus, but I don't build pedals for the sake of practicality. I just want to make something cool and versatile, while learning and having fun doing it. I am sure we all have our reasons for building our own pedals. I have a pretty cool box that I am designing, and adding a USB out would be a very cool feature for it.

 

[giovanni]

Did you check out Adafruit? They may be a good source of inspiration. Good luck!

 

[ICTRock]

I am sure it would be. I mean, I already have a PreSonus, but I don't build pedals for the sake of practicality. I just want to make something cool and versatile, while learning and having fun doing it. I am sure we all have our reasons for building our own pedals. I have a pretty cool box that I am designing, and adding a USB out would be a very cool feature for it.

I don't know where you jump into this in a DIY fashion that doesn't include a lot of technical knowledge in interface programming, signal processing, computer engineering, and a few other niche disciplines that you likely don't have.

https://en.wikipedia.org/wiki/Analog-to-digital_converter covers so much more than I'd be willing to take on for a DIY project and that's just the jump from analog to digital, not the digital audio to USB, or USB to some software running on the OS of your choice

 

[giovanni]

I think this thread may be relevant.

 

[Steve973]

I don't know where you jump into this in a DIY fashion that doesn't include a lot of technical knowledge in interface programming, signal processing, computer engineering, and a few other niche disciplines that you likely don't have.

https://en.wikipedia.org/wiki/Analog-to-digital_converter covers so much more than I'd be willing to take on for a DIY project and that's just the jump from analog to digital, not the digital audio to USB, or USB to some software running on the OS of your choice

Hello, @ICTRock and thanks for the reply. As I alluded to in my first post, I am not an EE. But I have adequate science and technical background to undertake this effort as long as I have a little guidance. I am a very fast learner, particularly when I am interested enough. Engineering the entire solution from scratch would be beyond my current capabilities. The other way I look at it is like this: though I understand the principles of conversion from analog to digital, for the purposes of designing such a circuit into a board, I do not need to be able to design the ADC and USB codec myself, and from scratch. Rather, I need to understand which components to use, and I might need some help with how to connect them. As a member of a DIY forum, do you typically look at a challenge and think why you cannot successfully do it? Or do you find out how you can do it? Personally, I welcome challenges. Where you are least comfortable is where you can find the most growth.

 

[szukalski]

We're here to learn and help, so let's support this endeavour instead of striking it down.

The technical jump doesn't have to be as daunting as what others are saying, take a look at a Raspberry Pi and some of the interface modules that are on offer. Then it's a case of redirecting a stream from here to there, maybe fiddling with some buffer options. Once you have the concept going with a (relatively) modular approach, then break your components down into smaller parts. A RPi is pretty chunky for a pedal, but the same concept will apply to smaller compute.

 

[ICTRock]

We're here to learn and help, so let's support this endeavour instead of striking it down.

The technical jump doesn't have to be as daunting as what others are saying, take a look at a Raspberry Pi and some of the interface modules that are on offer. Then it's a case of redirecting a stream from here to there, maybe fiddling with some buffer options. Once you have the concept going with a (relatively) modular approach, then break your components down into smaller parts. A RPi is pretty chunky for a pedal, but the same concept will apply to smaller compute.

You're welcome to invest as much of your time and energy on this as you'd like but is it really a project request at this point?

 

[szukalski]

We try to be the person we want to be. Helping a community grow is always a worthy aim.

Actions and IPs will always show our true selves.

 

[phi1]

Last month I went hunting for a raspberry pi and they seem pretty hard to come by for a good price at the moment.

My middle of the road idea would be to buy the smallest usb interface you can find and harvest the guts for your project. To me, for this particular situation, that’s no less diy than building a ready-made project, since you’re already integrating it into your own larger creation. Many times it requires more creativity to retro-fit something than build a ready made solution.

As far as growth, you can learn a lot by studying the hardware used in that unit (or in your PreSonus), in terms of the analog signal flow (buffers, preamps, filters, etc), and the chip used for usb conversion. Also, read, re-read, look up terms from the daisy thread linked a few posts back, seems like some clues on what tech hurdles there are, though a lot of it went over my head.

 

[Steve973]

You're welcome to invest as much of your time and energy on this as you'd like but is it really a project request at this point?

Keep in mind that you elected to respond. If you don't like something, you have the prerogative to keep on scrolling. If the admins do not think this is appropriate for this particular forum, then they can delete or move this thread and I completely understand. But you probably have more valuable things to do with your time than to police these forums as a new member. Also note that you decided to make assumptions about what I was capable of doing/understanding in terms of this project. But I did not jump on you for that. So, please, jump in and help if you are interested in the subject and capable of lending constructive help. Otherwise, I'll see you around. Thanks again.

 

[vigilante398]

STM32 has a ready-to-go USB audio library so it shouldn't be too hard to implement if you're really intent on doing a DIY interface, but there are plenty of affordable commercially available options out there. I found out about it while working on an unrelated STM32 project and I've wanted to mess around with the idea, but haven't gotten around to it yet.