DIY digital xover, what do you think?

[bogicp]

Hi all,

Ok, I'm probably... hm, but never mind, what do you think about this?



I see that almost all things needed for xover already exist and because tools for FPGA are free of charge, why not ?

Any opinions will be highly appreciated.

Best regards,

boggy

 

[ShinOBIWAN]

The Spartan DSP is used in the RME HDSP series. Very good DSP.

 

[bogicp]

Hello ShinOBIWAN,

Thank you for your reply,

The Spartan DSP is used in the RME HDSP series. Very good DSP.

Actually, Spartan isn't dedicated DSP chip, it's FPGA - a Field Programmable Gate Array, they can do all digital tasks if you program it for this and if chip size is large enough for your tasks.
You can put in same chip, for example, 8bit microcontroller, DSP core, USB core, UART core, etc..
etc...
All wiring you can do inside chip, and this can be very, very fast...

Yes, it's used also in Apogee, Lynx, ... devices.

You cannot expect to have DSP functions for free of charge, but you can do it by yourself for free of charge ... with dedicated DSP chips you must buy programming tools... with FPGA you may use free tools...
This is some of more reasons why FPGA

Best regards,

Boggy

 

[ShinOBIWAN]

Hello ShinOBIWAN,

Thank you for your reply,




Actually, Spartan isn't dedicated DSP chip, it's FPGA - a Field Programmable Gate Array, they can do all digital tasks if you program it for this and if chip size is large enough for your tasks.
You can put in same chip, for example, 8bit microcontroller, DSP core, USB core, UART core, etc..
etc...
All wiring you can do inside chip, and this can be very, very fast...

Yes, it's used also in Apogee, Lynx, ... devices.

You cannot expect to have DSP functions for free of charge, but you can do it by yourself for free of charge ... with dedicated DSP chips you must buy programming tools... with FPGA you may use free tools...
This is some of more reasons why FPGA

Best regards,

Boggy

I always thought FPGA stood for Flat Pin Grid Array and was used as a term for surface mounting CPU's in PC's to the mothermoard ala. SMD.

Consider me re-educated

The Spartan is indeed a very flexible chip and the quality amd speed isn't bad either My RME HDSP3264 and HDSP5264 continue to impress me. They are used as a software based XO with FIR filters and DRC.

How much is Spartan charging for the FPGA? Are they demo boards? What about SHARC's?

 

[bogicp]

I always thought FPGA stood for Flat Pin Grid Array and was used as a term for surface mounting CPU's in PC's to the mothermoard ala. SMD.

Consider me re-educated

No problem

The Spartan is indeed a very flexible chip and the quality amd speed isn't bad either My RME HDSP3264 and HDSP5264 continue to impress me. They are used as a software based XO with FIR filters and DRC.

How much is Spartan charging for the FPGA?

At http://www.nuhorizons.com you can find XC3S1500 in FG456 package for about $80, for other devices (smaller packages, for example, are cheaper) you may contact it. Other providers for Xilinx devices are Digikey (they don't have Spartan3 devices) and Memec.

Are they demo boards?

Yes, look at link

What about SHARC's?

You must buy Analog Devices software tool for SHARC. Xilinx provide software tool for free (you can use it for maximum Spartan 3 with 1,500,000 gates chips, and this is enough for most of applications)

With FPGA you must buy only chips, not tools.

With FPGA you can do DSP more efficiently than with dedicated DSP chips, but FPGA DSP isn't easy to program in copy/paste sense from some vendor's examples. But loudspeaker crossover DSP needs are very simple. You can do IIR, FIR, some delay etc... that's all. But you can do more complicated things with FPGA in crossovers... if you have needs or curiosity for it.

You can write program for FPGA in vhdl, and in this form, source can be shared with others.




Best regards,

boggy

 

[paulb]

You can write program for FPGA in vhdl, and in this form, source can be shared with others.

Where do you find vhdl source for these types of filters? Is there a users group or something through Xilinx?

 

[wigginjs]

This project goes over my head in terms of complexity, but I'm going to be following this thread and just thought I'd show my interest. Sounds really neat and if it gets to a point where there is a kit or something I'd most likely be interested in trying it out.

 

[bogicp]

Where do you find vhdl source for these types of filters? Is there a users group or something through Xilinx?

I can write vhdl for crossover purposes, other things already exists in some level of completness at Open Cores .

Best regards,

boggy

 

[bogicp]

This project goes over my head in terms of complexity,

I understand you, but this idea (free and open digital crossover is in my mind for a long time), and I cannot find any other thing for loudspeakers with same flexibility,
If I understand good loudspeaker problems, most of it are in crossover section and drivers... in other cases we cannot do much more than we do today.

but I'm going to be following this thread and just thought I'd show my interest.

Thanks.

Sounds really neat and if it gets to a point where there is a kit or something I'd most likely be interested in trying it out.

If people are interested for this project, it's not that hard work to prepare some quantity of PCBs, with vendor lists you can buy parts. etc. With some documentation... this is almost a kit.



Best regards,

boggy

 

[paulb]

I can write vhdl for crossover purposes, other things already exists in some level of completness at Open Cores .

At that site I see this: "This page is here because the site administrator has changed the configuration of this web server. Please contact the person responsible for maintaining this server with questions. "

 

[paulb]

On the whole, looks like a very good idea. I'd like to be able to tweak parameters on the fly (using a PC) while doing measurements and listening tests, then burn the configuration into Flash for permanent use.
You could scale back the complexity to make things easier to get going. How about one analog in, one digital in, and just USB or RS-232 for control? And I don't imagine we need all those different types of memory. SRAM and SDRAM? Flash, Flash PROM, and Compact Flash?

 

[bogicp]

At that site I see this: "This page is here because the site administrator has changed the configuration of this web server. Please contact the person responsible for maintaining this server with questions. "

I see, they have some problems with server...

you can try one of mirrors


best regards,

boggy

 

[bogicp]

On the whole, looks like a very good idea. I'd like to be able to tweak parameters on the fly (using a PC) while doing measurements and listening tests, then burn the configuration into Flash for permanent use.

Yes, and you can do some things that isn't provided with commercialy avaliable devices...

You could scale back the complexity to make things easier to get going. How about one analog in, one digital in, and just USB or RS-232 for control?

Hey, I don't think that all this things we must have at board, this is a preliminary block shematic with all possibilities included

We can do generic interface and other interfaces can be daughter boards...

And I don't imagine we need all those different types of memory. SRAM and SDRAM?

SRAM... if we need fast memory access for some purposes...
but for audio, with parallel access to memory, we probably don't need SRAM, because SDRAM is fast enough

Flash, Flash PROM, and Compact Flash?

Flash: this is a memory for coefficients and presets. You need this.
Flash PROM is for FPGA configuration program, you also need this.
Compact Flash is also configuration device, but optional... Compact Flash devices are cheap today... You can send this programmed devices via standard mail to your friends (if they cannot program it because any reason), etc...

We can discuss about all this possibilities...


Best regards,

boggy

 

[wigginjs]

I understand you, but this idea (free and open digital crossover is in my mind for a long time), and I cannot find any other thing for loudspeakers with same flexibility,
If I understand good loudspeaker problems, most of it are in crossover section and drivers... in other cases we cannot do much more than we do today.



Thanks.



If people are interested for this project, it's not that hard work to prepare some quantity of PCBs, with vendor lists you can buy parts. etc. With some documentation... this is almost a kit.



Best regards,

boggy

I guess thats what I meant. I consider ready-made PCBs with documentation and parts list a kit, but I guess it's not quite there. Either way, I'd be in.

 

[blip1882]

Just a note of support... I'd definitely be interested in a digital XO kit.... especially if it could be easily tweaked in real time.

 

[DSP_Geek]

If y'all don't mind writing a spot of DSP code (I'm OK with it), check out the Analog Devices Blackfin EZ-Kit: includes a rocking DSP, 4 analog ins, 6 analog outs, decent-looking codec, big pile of memory, and development software, all for $400.

http://www.analog.com/en/epHSProd/0,2461,BF533%2DHARDWARE,00.html


I'm thinking of getting one.


Cheers,
Francois.

 

[bogicp]

Hi all,

FYI
OpenCores web site is now up and running.
OpenCores

Best regards,

boggy

 

[jacklelad]

I think this is an excellent idea and would be interested in purchasing a kit.

As well as the advantages already mentioned it would use much less power than a PC and therefore be better for the environment. Also a lot smaller too. Probably more stable than a PC as well.