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Old 23rd May 2010, 03:04 AM   #1
chaparK is offline chaparK  Luxembourg
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Lightbulb DSP Xover project

Hi all,

I have a few spare DSP boards left from a past project, they would nicely fit now a new Xover project.
I'm thinking of writing a computer application + DSP firmware that would allow the user to set crossover filters, parametric EQ, delay lines and gains, in order to resell these boards that i'm not likely to use.

The purpose of this thread is to poll the interest of potential buyers and collect requirements before starting to work on it.

What i'd like to know is:
- Is there anyone interested in such a board?
- What kind of processing should i make available, apart from Xover (Buuteworth/Linkwitz-Riley/Bessel up to 48dB/oct), PEQ, shelving filters, delays and gains?
- What form should the project take? Me doing the whole stuff in a closed and controlled manner, or releasing an open-source framework?
- Whatever comes to your mind.

Here are some details about the board itself:



Click the image to open in full size.

- The DSP is a Freescale DSP56321 clocked at 275 MHz. It's capable of 275 MMACS, has a coprocessor and boasts plenty of RAM, enough to make a 4 second delay line at CD sampling frequency. The DSP is 24-bit fix-point with 56-bit accumulators. It's been a classic architecture for years in DSP for audio processing, and i guess that many of you have some custom code for it.
275 MMACS is A LOT! Enough for steep crossover filters, countless PEQ or FIR filtering.

- There's a USB connection allowing transfers of data to/from PC up to 8Mbit/s (USB High-Speed). The controller chip is manufactured by FTDI.

- There's a codec onboard with 2 analog inputs and 6 analog outputs. The chip is by Analog Devices ref. AD1838A. ADCs and DACs have both over 100 dB dynamic range, inputs and outputs are balanced or unbalanced. There are plenty of clock options, with 2 quartz onboard switcheable from the DSP.

- There's an expansion connector for separate I2S in and out, SPI and GPIO. Everything is there if you want to drive your own ADCs/DACs/SPDIF tranceivers.

- There's an other port with 5 outputs and 3 inputs for leds and pushbuttons.

- JTAG is also onboard if you wish to write your own code.

- The board requires 5V and +/-12V. The rest of the power supply is included on board with quality TI regulators. I can supply the matching SMPS.

- Finally, it's a high-quality board with 6 layers, vast ground planes and branded chips.

Best!

chaparK

Last edited by chaparK; 23rd May 2010 at 03:11 AM. Reason: Added pic
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Old 23rd May 2010, 07:32 AM   #2
col is offline col  Australia
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looks like a very interesting board! You might want to get one of the moderators to move the thread to the "swap meet" section though as you are talking about sales. Would be nice to have a 3 or 4 way DSP crossover with linux opensource software for setting up Nice to have all balanced connections!

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Old 23rd May 2010, 07:45 AM   #3
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by col View Post
looks like a very interesting board! You might want to get one of the moderators to move the thread to the "swap meet" section though as you are talking about sales. Would be nice to have a 3 or 4 way DSP crossover with linux opensource software for setting up Nice to have all balanced connections!

col.
Thanks col for your comment, the boards are pretty nice indeed.
I just checked the data relative to the codec: dynamic range is 105 dB for the ADCs, and 108 dB for the DACs (A-weighted). Pretty usable.

The pic shows the prototype. Production boards are red and have screw terminals for the power supply leads.

So far i'm not selling anything. Just gathering suggestions and interest. It's not a topic for selling anything, but for discussing what would be cool to have in the software
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Old 23rd May 2010, 08:14 AM   #4
col is offline col  Australia
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yeah the board looks great! Iv'e been watching the miniDSP stuff a bit and would have probably invested long ago if it wasn't for the fact that there is no balanced connectivity and the plugin software runs on windows. What about making the setup software using something that is multi-platform like Java? Also, for pro audio use it would be better if it was 4 way.

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Old 23rd May 2010, 08:24 AM   #5
chaparK is offline chaparK  Luxembourg
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Quote:
Originally Posted by col View Post
yeah the board looks great! Iv'e been watching the miniDSP stuff a bit and would have probably invested long ago if it wasn't for the fact that there is no balanced connectivity and the plugin software runs on windows. What about making the setup software using something that is multi-platform like Java? Also, for pro audio use it would be better if it was 4 way.

col.
Ok so let's start the list of features:

- 4-way crossovers
- Multi-platform

I have to say that i had in mind to make a Windows app as well. But you're right: the app should be multi-platform. Don't like Java though. Maybe Python? I know there's a Python wrapper around the FTDI API for USB com. Haven't tested it though.
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Old 23rd May 2010, 08:37 AM   #6
Shaun is offline Shaun  South Africa
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I previously posted the following wish-list in another thread (so not all relevant to your hardware):

Quote:
Originally Posted by Shaun View Post
I'd say, off the cuff:

1. high-pass filters
2. low-pass filters
3. shelving filters
4. Notch filters
5. Attenuators
6. Arbitrary slopes for all filters
7. Time delays
8. Dithering
9. Equalisation, with selectable preset/programmed filters
10. Digital Room Correction (also with [multiple] selectable configurations)
11. Analogue volume controls [or equivalent scheme for avoiding loss of low-level resolution]
12. Master/slave control of volume controls so that master loudspeaker controls system's overall volume
13. Remote control
14. Selectable Digital and analogue inputs into master loudspeaker
15. Digital or dot matrix display of system status (volume levels, inputs and muted channels).
16. Control outputs to turn on/off/mute power amplifiers.
17. Control panel for in case remote control fails (battery low or fault).
How many boards do you have, and at what cost?

Bohdan, the author of SoundEasy loudspeaker design software, wants to partner up with someone who can provide the DSP hardware for his latest DSP utilities. See SoundEasy product page.

I'm very much interested! Good luck with this project.
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Old 23rd May 2010, 08:39 AM   #7
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very interesting indeed. do you have a rough idea of what it will sell for?

ive just bought a miniDSP + MiniDigi board to play with, and so far im fairly impressed, though its not without drawbacks. the first being (as col says) only windows interface - luckily i do have a windows box to program it, but ideally i'd want something i can run from a mac (which is my audio workstation). the interface is very pretty, but very 'laggy' when running live to the board (no big deal, set it up offline then sync) also, if you are going to make a pretty graphical interface, then it ought to be editable graphically - not just from edit boxes. that said, give me raw functionality over pretty interface any day.

the ability to edit the parameters of say, parametric EQ's, live - so if you are eq'ing a system, you dont have to edit the setup file, download the board, recheck your freq response, edit params, download, etc. its important (imho) to be able to make changes in real time. this is something you can do with the miniDSP

the miniDSP 'plugins' system is a bit weird. I'd rather just pay more money upfront and have all the options of all the plugins available as settings, rather than be limited to whichever particular optionsets they decide they will include in a given plugin. eg the ability to choose whether to use a graphic eq or a peq at a given point in the signal chain.

one bit of *essential* functionality missing from the miniDSP is output limiters.

anyway, count me in as interested (if the price isnt too high)

I second Col in saying Hooray for Balanced ins and outs...

cheers,

ben
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Old 23rd May 2010, 08:41 AM   #8
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Quote:
Originally Posted by Shaun View Post
I previously posted the following wish-list in another thread (so not all relevant to your hardware): <big list>
Hey Shaun. is that list in order of importance?
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Old 23rd May 2010, 08:56 AM   #9
col is offline col  Australia
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Quote:
Originally Posted by chaparK View Post
Ok so let's start the list of features:

- 4-way crossovers
- Multi-platform

I have to say that i had in mind to make a Windows app as well. But you're right: the app should be multi-platform. Don't like Java though. Maybe Python? I know there's a Python wrapper around the FTDI API for USB com. Haven't tested it though.
Python even better! There are a lot of people that can program in python and if the software is opensource you would hopefully get programmers contributing.

col.
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Old 23rd May 2010, 09:11 AM   #10
Shaun is offline Shaun  South Africa
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Quote:
Originally Posted by anomalous View Post
Hey Shaun. is that list in order of importance?
No, it is just the factors that were foremost in my mind at the time, not in order of preference. I had been investigating the requirements for a DSP-based active crossover for my Meridian D6000 speakers which I bought minus the DSP board. I have actually purchased the DCN23 from GroundSound. I have yet to build the amplifiers, though.

I am very much pumped about DSP audio since I started enquiring about them.
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