Digital BBD concept looking for comments and beta testers

[giovanni]

Late to this party, but I’m really interested into trying out a prototype. Do you have a basic example schematic on how to use it?

I have a few questions:
* What do you expect the market for this to be?
* If the device does not sound like a BBD, I wonder why people would prefer it to some other DSP chip? What’s the value proposition?
* It would be very interesting to explore ways to control the defects and noise level to simulate a real BBD, would that be possible? This ties into the previous question of course!

 

[passtheducky]

The advantage over a BBD is that it is multitap unlike any of todays readily available parts. The advantage over plain DSP part is that you don’t have to write any software.

 

[Cabintech]

Late to this party, but I’m really interested into trying out a prototype. Do you have a basic example schematic on how to use it?

I have a few questions:
* What do you expect the market for this to be?
* If the device does not sound like a BBD, I wonder why people would prefer it to some other DSP chip? What’s the value proposition?
* It would be very interesting to explore ways to control the defects and noise level to simulate a real BBD, would that be possible? This ties into the previous question of course!

The "does it sound like a BBD" question is really about what you are trying to achieve with a given design. It will have some sonic characteristics of BBDs like pitch shifting when the delay is modulated. It will not have others like the drop off in frequency response with longer delay times (due to lower sampling rates). If that is good or bad is just a matter of what you want. If you don't want significantly better S/N ratio, then by all means add in some noise! If you want that muffled sound then by all means add a filter! But now those are design choices instead of unavoidable characteristics of the technology.

We are looking at emulating some of those characteristics in the DSP, but they could be turned on or off by jumpers or control inputs. I don't think we know enough about what "defects" would be considered useful to do that yet, I hope the beta program and experimentation will reveal some of that. Its possible that firmware updates could add features like this without any hardware changes.

Oh yeah, value proposition:
- The ability to build delay-based effects using analog feedback and modulation techniques with far better S/N and frequency response than existing BBD designs
- Available, affordable, and supported multi-tap delay device for MN3011 style effects
- New and interesting effects not possible with any hardware BBD device (VC dynamic positioning of taps, chaining for more tap points and longer delays, ...)
- Maybe more cost effective for designs using multiple BBD chips (e.g. a single CT3660 is equivalent to (4) MN3008/9). Cost is TBD.

My feeling is that this is targeted for new designs, not really for retro-fitting into existing systems although there could be some of that for specific use cases.

 

[Cabintech]

A quick update... after moving all our shipping and development to a new location, we are finally getting the CT3660 prototype up and running on the bench.

 

[giovanni]

The "does it sound like a BBD" question is really about what you are trying to achieve with a given design. It will have some sonic characteristics of BBDs like pitch shifting when the delay is modulated. It will not have others like the drop off in frequency response with longer delay times (due to lower sampling rates). If that is good or bad is just a matter of what you want. If you don't want significantly better S/N ratio, then by all means add in some noise! If you want that muffled sound then by all means add a filter! But now those are design choices instead of unavoidable characteristics of the technology.

We are looking at emulating some of those characteristics in the DSP, but they could be turned on or off by jumpers or control inputs. I don't think we know enough about what "defects" would be considered useful to do that yet, I hope the beta program and experimentation will reveal some of that. Its possible that firmware updates could add features like this without any hardware changes.

Oh yeah, value proposition:
- The ability to build delay-based effects using analog feedback and modulation techniques with far better S/N and frequency response than existing BBD designs
- Available, affordable, and supported multi-tap delay device for MN3011 style effects
- New and interesting effects not possible with any hardware BBD device (VC dynamic positioning of taps, chaining for more tap points and longer delays, ...)
- Maybe more cost effective for designs using multiple BBD chips (e.g. a single CT3660 is equivalent to (4) MN3008/9). Cost is TBD.

My feeling is that this is targeted for new designs, not really for retro-fitting into existing systems although there could be some of that for specific use cases.

That all sounds very compelling! I was wondering about the tonal characteristics and specifically that BBD “character” because people (myself included!) seem to gravitate towards it as a feature of those devices rather than a problem to work around. But you’re right, testing the device will tell us how it performs in a real life pedal.

Do let me know if I can help with the testing!

 

[Cabintech]

Do let me know if I can help with the testing!

We will contact everyone that is interested in beta testing (assuming we have enough prototypes) as soon as we finish testing and make some updates to the firmware and documentation.

 

[t1redhands]

Probably about 2 weeks before we get them in-house, then some assembly and testing. If you are interested in beta testing, let us know!

I would LOVE to help test this! Thanks!

 

[DGWVI]

If any spots are still available, I'm down to mess with one of these

 

[Cabintech]

If any spots are still available, I'm down to mess with one of these

Thanks! Might depend on how many good boards we have when we are done building them out. We will let you know...

 

[Cabintech]

Finally, after a move of our facilities to a new location, we are underway on this project again. First hardware is fully functional! The Bordbrain mixer has been a great bench tool to level set inputs and outputs, mix returns, etc. I'll post a video later with a bit of sound track and a simple multi-tap delay mix configuration.

Next step is build more modules for beta testers, and do some test measurements for S/N, etc.

 

[music6000]

Finally, after a move of our facilities to a new location, we are underway on this project again. First hardware is fully functional! The Bordbrain mixer has been a great bench tool to level set inputs and outputs, mix returns, etc. I'll post a video later with a bit of sound track and a simple multi-tap delay mix configuration.

Next step is build more modules for beta testers, and do some test measurements for S/N, etc.
View attachment 63109

In the PT2339 delays I believe the inclusion of a tone control gives the user how much it influences the digital/ analog path sounds!
My Wampler Analog Echo is a good example from 2010, I think it's a cool delay & we have 13 years of technology since then.
Here is the Wamper in action 14 years ago:

 

[Cabintech]

OK, this was supposed to be a quick video but somehow it turned into 10 minutes. Probably way too much talking by some dummy . If you want to skip right to the demo, use the chapter links in the description area below the video.

More to come later, but for now we are focused on building out the rest of the prototype modules, putting final touches on the firmware, updating docs, and getting these out to beta testers.

00:00 Intro, overview of CT3680, bench setup
05:22 Demo configuration
07:10 Audio demo

 

[passtheducky]

Nice progress.

This is kind of tangential, but I'm curious how you sent the data back to the host. Did you bit bang one of the user digital outputs or something?

 

[Cabintech]

Nice progress.

This is kind of tangential, but I'm curious how you sent the data back to the host. Did you bit bang one of the user digital outputs or something?

Yes, there is a convenient 48KHz clock for sending a 48Kbps data stream. Been very handy for debugging firmware and validating the hardware. Still not decided if we will document/support it (how useful would it be?).

 

[Cabintech]

The good news is that there is a lot of interest in beta testing.
The bad news is that we don't have enough prototype boards for everyone that expressed interest.
The good news is that we have ordered another batch.
The bad news is they will take 2 weeks+ to get here.

So for now we will make boards for as many as we can, in the order that we got the request. The rest will need to wait for the next batch of boards. Also that means if you want to experiment with chaining multiple modules together we can supply only one for now, and we can follow up with another when the 2nd batch arrives.

Thanks for all the interest!

 

[Cabintech]

OK, email has gone out to all the beta testers requesting shipping addresses, etc. A few we have not heard from (@Gordo , @Robert ) let us know if you are still interested.

The 2nd batch of boards has arrived, so we will be getting them assembled and shipping those out in the next week or so.

 

[CR0SSBL4DE]

Hi, I'm new here and I just learned about this.
Is the CV controlling an internal clock for the BBD emulation? Part of the BBD modulated sound is the aliasing, specially on slower clock speeds (the sampling frequency changes, but the antialiasing filter cutoff freq does not. Also the AA filter is a 2nd or 3rd order filter in classic designs).
Kudos for the work done!

 

[passtheducky]

The goal of this project isn’t to make something that sounds like a BBD. It was just an analogy.

 

[CR0SSBL4DE]

The goal of this project isn’t to make something that sounds like a BBD. It was just an analogy.

Oh, my bad then!

 

[Cabintech]

Hi, I'm new here and I just learned about this.
Is the CV controlling an internal clock for the BBD emulation? Part of the BBD modulated sound is the aliasing, specially on slower clock speeds (the sampling frequency changes, but the antialiasing filter cutoff freq does not. Also the AA filter is a 2nd or 3rd order filter in classic designs).
Kudos for the work done!

The module uses a fixed (48kHz) sample rate regardless of delay time. So there is no 'natural' aliasing at longer delay times (lower clock speeds for traditional BBDs). For cases when that aliasing is desired we are looking at simulating it (as an option), but the beta modules will not have that.

It is interesting to think about how this module might implement this. In a real BBD the aliasing depends on the clock speed (= sample rate). But that sample rate happens at different delay times depending on what BBD chip you are using. In a 3x05 (4096 stages) a delay time of 20ms is at a clock rate of about 10kHz. A delay time of 20ms for a 3x07 is at a clock rate of about 25kHz. So at the same delay, these two chips would have different aliasing characteristics.

The CT3680 implements a delay that can span any current BBD chip, so how to know when (at what delay time) aliasing should start? Another CV value I suppose?