Digital BBD concept looking for comments and beta testers

[Passinwind]

I had to build up a second feedback mixer, the first one had stability issues. I may have herked the SMD opamp during hand soldering, which thankfully has only rarely happened over the last several years. Spent an hour or two tracking that down, whipped up a new board, and everything acts as intended now. Got in an hour plus with my new acoustic guitar into a very high resolution AudioKinesis 112 + horn cab with my DIY 500 watt amp. I ran the test pedal through my effects loop, it sounded great and the noise floor was exceptionally good, easily better than many or maybe even any of the rack processors I’ve owned over the years. I’m very impressed so far!

I’ll write up my first feedback email this evening, there’s plenty to unpack already. My build was a bit too quick and dirty, but now that I know what I’m working with I’ll clearly have to clean things up. Really looking forward to the production version, the board size reduction will be a nice bonus when I go from modular to a one or two board format.

 

[Passinwind]

Update: still playing with a single two tap delay, mostly working on fine tuning feedback schemes and gain staging. I've ordered some new five channel mixer PCBs of my own design to facilitate working with the 4 tap delay program, along with some simple eBay function generator boards to get me started on modulation effects. Still very happy with the sound quality for acoustic guitar, will start testing with bass later today probably. I'm waiting on a new pickup for my electric guitar and will get to testing with that too as soon as it comes in. And finally, I'm rebuilding an old two way cab to get set up with a stereo monitoring rig, and also have a little 2 x 4" cab I want to try as a satellite/ambience speaker.

 

[Cabintech]

From this mess...



To this...



CT3680 development/breakout board. Sorry beta testers, this does not fit the prototype modules...!

 

[Passinwind]

Satellite/acoustic guitar 8" + horn cab is now up and running:



Even with that big scary horn running pretty hot the noise floor of my various delay configs has been excellent so far. I'll be bumping up the complexity now, and start concentrating on the stereo aspect, including the new stereo image panning feature as soon as we get the firmware update done to my board. I'll be doing that on my end in a few days, so I can and will keep working on other bits and pieces until then. My LFO boards came in yesterday so I'll be making smoke as soon as I'm properly caffeinated.

 

[Cabintech]

Satellite/acoustic guitar 8" + horn cab is now up and running:

Nice! I want a pair of those!

 

[Passinwind]

Nice! I want a pair of those!

Me too, a local friend of mine has the matching one of the original pair and I am seriously thinking about trading something back for it and putting an 8 in it as well. There are some smaller versions of that horn that would probably work great in this application too, the cast aluminum 18 Sound one is massive overkill really. But since I already had a box for it and could just use the existing LPF I didn't see any point in buying a different one.

 

[Passinwind]

I'm on to my newly revamped electric guitar and program 4 now, finally. Working really well for slapback and doubling, and I'm noticing that in this config delay control interaction between taps feels noticeably different, i.e. more predictable. But I was getting some very useful 'verb effects using programs 0 or 1, so I think program switching will have to make it to my control panel eventually.

Sorted out a number of things in my wiring layout to make life a little easier as I get into stereo modulation effects. The cheap LFO I built up works fine but I need to add a simple DC offset circuit to plumb it into the DBBD. Time to decide how many knobs is too many, I reckon.

 

[Cabintech]

In the mail today... lots and lots of through-hole adapters, and rev 2 of the development board. Oh yeah, and a solder mask for the 40-pin SMT connector to see if we can speed up populating the DIL adapters and dev boards. That is a HUGE sheet of stainless for a TINY little mask area!

 

[Cabintech]

And the good news... from the beta testing we are confident in the hardware design, so the first run of CT3680 modules is now in production! We have more firmware ideas to implement, but the hardware is well settled.

That also gives us the ability to answer the question many have asked... what is it going to cost? If there are no surprises, single piece cost will be about $39, production quantities around $25, with some price breaks in between for small batch builders. In addition to the module itself, we also plan to stock:
40-pin edge connectors
DIL through-hole adapters (bare or with connector)
Dev boards (bare, with connector, or fully populated)

 

[Passinwind]

Great to see that your pricing came in a little under my ballpark estimate/recommendation I sent along in email feedback.

 

[Cabintech]

Great to see that your pricing came in a little under my ballpark estimate/recommendation I sent along in email feedback.

We try to always be conservative when estimating future pricing, just too many variables to have high confidence. Like when the builder's pricing system told us our boards weighed over 50 lbs and would cost >$400 to ship. Yup. They missed like 2 decimal places when entering a component weight... that got fixed, but there is always something unexpected every time we do a build...

 

[Passinwind]

We have created a means to update the CT3680 firmware in the field, although it requires some specialized hardware. For beta testers we can loan out that hardware if you are interested in the new features, just let us know.

I bit on this and just did my first in-field firmware update yesterday. There were a few swerves while I worked out getting everything to play nice from the command line on my new Win11 desktop box, but the process was pretty simple beyond that. So now I have the means to tweak stereo panning and depth via pedal control, with very minimal effort on my part as far as wiring and hardware. Onward!

 

[Cabintech]

FYI this product was announced yesterday and is for sale now on our website: https://cabintechglobal.com/ct3680

Modules will start shipping next week, dev boards the week after. We still have work to do on the firmware before loading it onto the production modules.

Would love to keep getting the feedback (here and by email). There are a lot of cool ideas floating and we would like to publish some reference designs.

We continue to look for ways to improve the firmware (one new program that will hopefully make it into the first shipment of production modules is a program with presets that can simulate the exact delay times, taps (and optionally) aliasing effects of any model of BBD from MN3001-MN3012).

 

[Passinwind]

Congratulations on getting your product to market in such a timely manner!

For my part, I now have a 1590D box loaded up with 13 pots, with one more hole in reserve for the moment while I work out my implementation of modulation functions. The new CV option for Program 5 that we upgraded my unit to is working well and I had a lot of fun experimenting with my new stereo monitoring rig for several days last week. Hoping to take the test box over to my weekly Friday night jam tomorrow so I can run a wider variety of instruments through it, and hopefully get a feel for where to take things next.

Using a cheap sig generator board from eBay has been working out fine for LFO functions for the moment but I will do my own next time around, for sure. I messed up the layout of my 5 channel summing mixer a little but managed to make it work fine by putting a few SMD caps on their sides, which lets 1210 format pieces work in 1206 slots...DOH!

My next testing phase will focus on feedback loop processing, which looks to be a pretty deep rabbit hole. Beyond that I think going to two (or more) CT3680 boards is going to be the play for the stereo-centric applications I'm mostly interested in. And if the noise floor stays even close to what I'm getting with a single board I'll be a very happy camper.

 

[Cabintech]

Congratulations on getting your product to market in such a timely manner!

For my part, I now have a 1590D box loaded up with 13 pots, with one more hole in reserve for the moment while I work out my implementation of modulation functions. The new CV option for Program 5 that we upgraded my unit to is working well and I had a lot of fun experimenting with my new stereo monitoring rig for several days last week. Hoping to take the test box over to my weekly Friday night jam tomorrow so I can run a wider variety of instruments through it, and hopefully get a feel for where to take things next.

Using a cheap sig generator board from eBay has been working out fine for LFO functions for the moment but I will do my own next time around, for sure. I messed up the layout of my 5 channel summing mixer a little but managed to make it work fine by putting a few SMD caps on their sides, which lets 1210 format pieces work in 1206 slots...DOH!

My next testing phase will focus on feedback loop processing, which looks to be a pretty deep rabbit hole. Beyond that I think going to two (or more) CT3680 boards is going to be the play for the stereo-centric applications I'm mostly interested in. And if the noise floor stays even close to what I'm getting with a single board I'll be a very happy camper.

Very cool! Never made a PCB layout error myself . Opps, they are documented in this thread....

Do you find stereo useful in live (jam) environments?

Curious about what is driving you to consider multiple modules for the stereo... is it the need for more independent delay lines, or for longer delays? Been thinking to maybe change program #4 that currently has 227ms on 3 lines. Would it be more useful to have 2 longer lines and a short one for the stereo effect? E.g. if channel 3 is only used for stereo effect it only needs to be 30ms. That would give ~100ms additional delay to each of the others:

Channel 1 325ms on output 1
Channel 2 325ms on output 2
Channel 3 30ms on outputs 3/4 with stereo effect

Would that work better?

Let us know what you think about the proposed change to program #4, gotta do it soon to make it into the production firmware release.

 

[Cabintech]

We are adding another program to the firmware on the production modules. This program is basically a whole bunch of presets to emulate almost any current or obsolete BBD chip. Need an MN3003? Maybe an old TDA1022 or SAD512? Here is the update to the development guide:

Program 6 (General BBD Emulation)

This program provides emulation of many different BBD chips including all MN30XX models MN3001-MN3010 (see Program 5 for MN3011), plus SAD512/SAD1024, TDA1022, and V3205, V3207, V3208. This program provides 4 independent delay lines, one for each audio input/output pair. Each line will emulate one of the BBD chips based on the configuration selected. See Configuration Selection below.

Emulation consists of setting fixed minimum and maximum delay times based on the BBD datasheets. Since the min/max delay time is defined by the BBD model, the global VC_DELAY_MIN and VC_DELAY_MAX values are not used. Each of the four VC_DELAY_X inputs defines the delay of a particular channel within the range defined by the BBD model. For example, a delay line configured for an MN3009 will have a minimum delay of 0.64ms (VC_DELAY_X at 0.0V) and maximum of 12.8ms (VC_DELAY_X at 3.3V).

Configuration Selection

Configurations define which BBD chips are emulated on which delay channel. 4 BBDs can be emulated at a time, in combinations defined by the configuration.

1 of 8 configurations can be chosen by the OPTION_1, OPTION_2, and OPTION_3 inputs. These form a binary number which selects one of the configurations (see table below). Each configuration emulates 4 BBD chips, each BBD on an independent delay line. For example, when configuration zero is selected (OPTION pins 1,2,3 = LOW) delay line 1 emulates an MN3003, line 2 is an MN3006, line 3 is an MN3007, and line 4 is an MN3008.

Configurations 0,1,2,3.4 define various combinations designed to provide a wide variety of delay lines in each configuration. All BBD models are represented in at least one of the configurations. Configurations 5,6,7 provide dual delay lines of 2 selected types useful for stereo applications.

The following table shows which BBDs (and associated delay times) are on which channels for each of the 8 configurations. To see which BBDs are in a particular configuration, read one column of the table. Min and max delay times are in msec.

 

[Passinwind]

Very cool! Never made a PCB layout error myself . Opps, they are documented in this thread....

Do you find stereo useful in live (jam) environments?

Curious about what is driving you to consider multiple modules for the stereo... is it the need for more independent delay lines, or for longer delays? Been thinking to maybe change program #4 that currently has 227ms on 3 lines. Would it be more useful to have 2 longer lines and a short one for the stereo effect? E.g. if channel 3 is only used for stereo effect it only needs to be 30ms. That would give ~100ms additional delay to each of the others:

Channel 1 325ms on output 1
Channel 2 325ms on output 2
Channel 3 30ms on outputs 3/4 with stereo effect

Would that work better?

Let us know what you think about the proposed change to program #4, gotta do it soon to make it into the production firmware release.

I like your proposed change a lot and would be more than happy to give it a whirl ASAP.

My primary motivation for adding another module would be to allow more taps for chorus effects, as my gold standard is probably still the old Rocktron Intellifex, which could do up to 8 taps with stereo panning on each tap. Stereo rigs served me especially well when I used to gig in a duo with just a drummer and I would switch between bass, guitar, and guitar synth often (plus vocals), even during the same song sometimes. But to be honest, I mostly find it to be something that really enhances my home practice regimen, and last week I did a few 2-3 hour practice sessions with virtually no breaks, which was a bit too much given how short a time I've been playing acoustic guitar for. Hopefully this week I can really dive into using my new pedal with bass too, which I still haven't gotten around to yet.

 

[Cabintech]

After one last final this-is-the-last-firmware-change-no-really-I-mean-it, modules are being loaded, packed, and ready to ship today.

 

[Cabintech]

I like your proposed change a lot and would be more than happy to give it a whirl ASAP.

My primary motivation for adding another module would be to allow more taps for chorus effects, as my gold standard is probably still the old Rocktron Intellifex, which could do up to 8 taps with stereo panning on each tap. Stereo rigs served me especially well when I used to gig in a duo with just a drummer and I would switch between bass, guitar, and guitar synth often (plus vocals), even during the same song sometimes. But to be honest, I mostly find it to be something that really enhances my home practice regimen, and last week I did a few 2-3 hour practice sessions with virtually no breaks, which was a bit too much given how short a time I've been playing acoustic guitar for. Hopefully this week I can really dive into using my new pedal with bass too, which I still haven't gotten around to yet.

Got this change in before the final cut of firmware R1. Online docs are updated. Sorry cannot update your beta module with this, the firmware has evolved such that it will not run properly on the beta hardware, but new stuff is heading your way shortly

 

[Passinwind]

Got this change in before the final cut of firmware R1. Online docs are updated. Sorry cannot update your beta module with this, the firmware has evolved such that it will not run properly on the beta hardware, but new stuff is heading your way shortly

All good, I'm more than happy with what I have for now and among other things I still have to figure out how I'm going to implement a stereo cab config on the bass side.