Tocxic Instruments launches its crowdfunding campaign !

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Tocxic Instruments launches its crowdfunding campaign !

Postby JiM » 16 Mar 2015, 00:29

Hi all !
I hope a little advertisement here in the Café is not against the rules, i think this may be of interest.
A good friend of mine (actually a bandmate) is creating a new line of guitars, focused on the ease of use. No more cables to untangle, there is an integrated digital wireless transmitter. No more twisted strap, there is an integrated strap furling system. And the design is modular, with completely customizable elements.

Image

You can find more details on the KissKissBankBank website :
http://www.kisskissbankbank.com/en/projects/tocxic-instruments-pour-un-plaisir-de-jeu-immediat (hopefully everything is translated in english, if not feel free to ask)
Some pictures of the development works is on our Facebook page as well.
I'd be grateful if you could pass around the information, and maybe become one of our sponsors. Be quick, the campaing runs until the 19th of April !

Full disclosure : I'm involved in the design of the electronics, both passive guitar circuit and digital wireless transmitter.
In addition, among the counterparts offered to sponsors there is a modified distortion pedal. It is indeed a Joyo Crunch Distortion, which i modify into a fuzzy monster, by adding a silicon diode in the feeback loop of the second opamp stage, for nasty asymmetric clipping. :twisted:
Nothing like Freekish B., the point is not to fool people into buying a fake boutique pedal, it's just to provide a nice couterpart for valuable sponsors. The main project is building guitars, not stompboxes. But having some digital electronics inside the instrument opens the door to lots of interesting possibilies ... :wink:
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby Dirk_Hendrik » 16 Mar 2015, 15:54

"can" it stil be used with a cable and, wether or not, what's the brand and frequency of the wireless system? (read: the 2.4 Ghz band is getting awfully overcrowded).
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby JiM » 16 Mar 2015, 16:14

Hi Dirk,
Yes, there is still an output jack, at least as a safety in case of empty battery. The core guitar circuit remains passive.

The wireless system is based on a TI PurePath chipset (CC85xx series). It uses a clever frequency discovery mechanism to use efficiently the 2.4GHz band. A wonderfully integrated thing, with MCU, two DSPs, complete RF transceiver (LNA, ADC, DAC, PA ...) all in a tiny chip.
Now i have to figure out how to solder a QFN package. :slap:

:secret: One future plan is to add an onboard (in-ear) monitoring feature.
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby deafbutpicky » 16 Mar 2015, 19:10

The wireless stuff aside, this guitar in the picture looks way cool, reminds me a bit of Teuffel Guitars.
If it only was a one pice body... ,nevermind, I guess I'm old scool. Good luck.
I'm using capacitors to replace my guitar effects and give more clarity to the sound.
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby JiM » 16 Mar 2015, 21:47

deafbutpicky wrote:If it only was a one pice body... ,nevermind, I guess I'm old scool. Good luck.

Thanks !
The point of the modular design is to choose the pointy parts that you like, while keeping the cost of the center part reasonable. We can use various materials (wood, carbon or flax fiber, even leather wrapping !), colors, and shapes.

But we also have a more traditional design, actually the first being made (paint was done last weekend) :

Image
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby Dirk_Hendrik » 17 Mar 2015, 08:22

JiM wrote:The wireless system is based on a TI PurePath chipset (CC85xx series). It uses a clever frequency discovery mechanism to use efficiently the 2.4GHz band. A wonderfully integrated thing, with MCU, two DSPs, complete RF transceiver (LNA, ADC, DAC, PA ...) all in a tiny chip.


Without wanting to be a spoiler a latency of 10.6 (or higher) ms is way too high for this application. While delay below 15ms is barely audible as a delay it starts to get in the the field where playing feels unnatural. Other than that this delay range is in the flanging range. When having the dry sound as well as as the wet sound audible the user will experience this a form of flanging while moving around.
Sorry. Plain out of planes.

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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby Dirk_Hendrik » 21 Mar 2015, 10:35

errr

no threadkill intended :oops:
Sorry. Plain out of planes.

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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby modman » 21 Mar 2015, 14:54

Dirk_Hendrik wrote:errr

no threadkill intended :oops:


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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby DrNomis » 21 Mar 2015, 19:24

Have to admit that the guitars do look cool...... :thumbsup
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby Dirk_Hendrik » 21 Mar 2015, 20:08

Not really modman
Sorry. Plain out of planes.

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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby JiM » 22 Mar 2015, 00:57

No offense, it's just that i was busy finishing the first prototype. We did a metal show today (with concerts, artworks, radio debate ...), and showed the operational guitar for the first time :

Image
(that guy is the bass player of my band)

We had great feedback from local bands and visitors, most people liked either one of the designs (rarely both, but that's the point of offering the choice).
The strap fuling system looks like a gimmick, but the ability to ajust the length at will is very practical, everybody liked that.

About latency, it is indeed a topic we knew about from the beginning. We configure the chip for 12ms, which is as low as it gets, while still allowing for some packet retransmission in case of interference. Looking at that number it seems like a problem, but in use you don't really feel it : it's equivalent to the time it takes for acoustic waves to travel from an amp 4 meters away. No risk of flanging, as there is no point of having both the wire and wireless transmission at the same time. Today we demonstrated a range of at least 15 meters, and most of the latency came from the speed of sound, not the digital transmission !
Latency will indeed be a problem if we want to integrate in-ear monitoring (as we can transmit audio both ways), any ideas ?
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby mictester » 22 Mar 2015, 01:19

Having tried - and rejected - most digital approaches, I went back to the good old analogue diversity FM system at 1.2 GHz. With some basic companding and pre- and de-emphasis, I got the noise down to around -96dB so it was largely inaudible. To get consistent results over 50m (our target range) I had to use a bit more power than you might expect. Frequency stability was paramount to keep the transmitted signal right in the middle of the receiver passband to maximise the signal strength as far as the receiver was concerned and to minimise distortion. The transmitter was powered by a rechargeable battery pack (as used in Motorola phones) and we got about 8 hours per charge.
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby Dirk_Hendrik » 22 Mar 2015, 08:40

JiM wrote: any ideas ?

Yes. Study the digital systems from the big boys for their figures. And wonder why they all get their latency far below the 12 you mention.

And,
The arguments I brought up are among the most basic in designing a digital system. Choose to discard em and you will run into them sooner or later. Later probably meaning a customer complaint.
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby mictester » 22 Mar 2015, 10:22

Dirk_Hendrik wrote:
JiM wrote: any ideas ?

Yes. Study the digital systems from the big boys for their figures. And wonder why they all get their latency far below the 12 you mention.

And,
The arguments I brought up are among the most basic in designing a digital system. Choose to discard em and you will run into them sooner or later. Later probably meaning a customer complaint.



Dirk

The commonly available A to D converter chips that have enough dynamic range to be useful all have very significant conversion latency. The higher the definition, the longer the conversion times and the more power they consume. I went for the highest speed ICs available at the time and tried various word sizes in an effort to get to a good compromise but it was ultimately a waste of time ( :) ).

I went down this wrong route for a while when I should have been improving the analogue diversity approach! My customer was determined to be able to offer a "digital system" with "CD quality" but I had to persuade them that it wasn't the right approach. The analogue one is sold with "digital tuning" which partially satisfied them! The PLL controller gives 400 channels at 1.2GHz and it's possible to have instruments or vocal channels adjacent to each other without any interference. Each audio channel
goes to 18kHz and provides a bigger dynamic range than l could achieve with the digital nonsense with much lower distortion. Transmitter battery life is very good too.

I did find a Bluetooth chipset with negligible latency recently, but it has very few available channels and very short range. The dynamic range isn't too bad either, but the idea of phone calls coming through the PA at gigs brings back images of Spinal Tap!

This is just another of the places where digital is clearly inferior to the older ways of doing things!

The same applies to in-ear monitoring - the latencies double for two digital paths and it does sound weird with the internally conducted sound arriving ahead of the receiver signal! Again, the analogue diversity approach is significantly better than anything else.
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby Dirk_Hendrik » 22 Mar 2015, 10:57

mictester wrote:but it was ultimately a waste of time ( :) ).


Then you did noy try hard enough :secret: The fact that there's multiple brands of 2.4GHz systems available on the market suggest this to be the case too :blackeye Dynamic range is usuallty limited by the battery voltage (which in turn is a tradeoff between playing time vs voltage) and not by the converters. Stating the "old" way is better is, IMHO, an excuse to get out.

The converter latency is one of the delays in the system (2 actually, AD and DA). Added to that is the time needed to create some kind of "diversity" system, causeing samples to be transmitted multiple times. What you don't want is to add a +10ms time to that from the rf chips doing the tranmsmission.

If you look to, as an example, a middle class system like a Line6 relay you'll see they use 2 Rf chips and an FPGA to get the samples processed fast enough. While we can discuss a lot on Line6 and wether we like em or not we still will have to admit they have designers running around that give most of us here a good run for our money. Therefore if Line6 takes this approach to get their system fast enough it should be a suggestion for Jim not to rely on one Rf chip made for wireless headphones.
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby rocklander » 22 Mar 2015, 11:56

not wanting to further derail this thread, I bought one of these:
http://alesis.com/miclink-wireless

and as a singer I didn't notice any latency.. it's obviously there, but wasn't noticeable to my ears.. ..that said, I'm told I sing ahead of the beat anyway so a lil latency would prolly be helpful to me :oops:
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby JiM » 22 Mar 2015, 15:02

Dirk_Hendrik wrote:The converter latency is one of the delays in the system (2 actually, AD and DA). Added to that is the time needed to create some kind of "diversity" system, causeing samples to be transmitted multiple times. What you don't want is to add a +10ms time to that from the rf chips doing the tranmsmission.

Most of the latency comes from the protocol that ensures automatic channel discovery and link reliability (re-sending lost packets).
From the user guide : "selecting the audio latency is a trade-off between the audio stream delay and the robustness of the link; there is room for more retransmissions with a higher audio latency setting."

Dirk_Hendrik wrote:If you look to, as an example, a middle class system like a Line6 relay you'll see they use 2 Rf chips and an FPGA to get the samples processed fast enough. While we can discuss a lot on Line6 and wether we like em or not we still will have to admit they have designers running around that give most of us here a good run for our money. Therefore if Line6 takes this approach to get their system fast enough it should be a suggestion for Jim not to rely on one Rf chip made for wireless headphones.

I did research the Line6 Relay architecture, and found that : http://fccid.net/document.php?id=1096577
They use an older Chipcon device, which is not recommended for new designs, and require lots of external components (external MCU is mandatory). There is indeed a Lattice FPGA device in the receiver, i suppose it's used to switch between both receivers depending on link quality.
Do you mean that the way to go is to get rid of the link reliability protocol implemented in CC85xx, and craft robustness outside, e.g. with diversity ?
The single-chip design, with identical transmitter and receiver, is what makes the concept doable in DIY (except QFN soldering :blackeye). But crafting a more complex solution like Line6's, which i should thoretically be able to do, would take me ages ... and lots of wasted prototypes.
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby JiM » 07 Apr 2015, 23:15

Here is a quick demo of the modded distortion pedal:


Link

It's used with a Les Paul Standard and a Fender Hot Rod Deluxe, miked with a SM57 straight into the soundcard, no processing.

There is also a video from the metal festival i mentioned earlier:

Link

Please check the crowdfunding campaign, there's just 12 days left !
http://www.kisskissbankbank.com/en/proj ... u-immediat
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Re: Tocxic Instruments launches its crowdfunding campaign !

Postby JiM » 18 Apr 2015, 16:49

Just one day left!

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