anyone had any experiance with DSPs?

[kipman725]

hello ha anyone had any experience with these devices? I want to do this:

..............Digital outs
............... ^ ......^
Instrument>ADC>DSP>ADC>Amplifier>Speaker

using the DSP for things like octave shifts, distortion, noise removal, tone controls etc.

what equipment will I need?
Books to read?
Knowlage needed? (I'm pretty good at reduced instruction set TASM assembler but have only worked with Harvard architecture devices and have done A level maths)
Where to get the ICs? (all I can find are the company's that have a minimum order of thousands of units)

also advise on what speakers can get to the lowest frequency's with the minimum attenuation.

 

[perfectturmoil]

Hey

http://www.analog.com/en/prod/0,2877,ADAU1701,00.html

Look into this - I just got a real neat presentation about this product at my new hire orientation.. It does some of exactly what you want.. Its all programmable via a 'drag and drop' signal flow software suite (sigmastudio) which seemed to be very powerful.. and useful..

You can also build your own blocks in the devices assembly code to roll your own processing..

It has built in blocks for compression, pass filtering, reverb, chorus, phasing, etc...

I think the current model may have trouble with octave shifting (there was something that someone asked that I didn't hear the question and they said the next revision takes it... Don't know if it was frequency shifting..)

The application engineers for this product are wicked cool too.. So I would suggest considering this one.. It seems available at digikey for 8 bucks.. You might even score a free sample from ADI if you ask and tell em what you're doing..

 

[_atari_]

That looks marvelous (on paper). I am currently planning to construct some kind of Über-DAC for USB-audio (I know lots of problems).

But do you know how to get the Studio and what the pricing is?

 

[perfectturmoil]

They said SigmaStudio is free for use with the SigmaDSP chips..

I do NOT know the cost of an evaluation board.. Those can tend to be expensive.. Its neat - SigmaStudio controlling the chip on an eval board gives you full access realtime (as in, no simulation) to all the features through the USB programming.. You can build a filter, start playing something, mess with all the characteristics and hear it in real time. Then whatever you choose can be built in to the burn and several of your features can be connected directly to whatever 'knobs' you set up (theres a certain number of mappable inputs)... And everything is accessable via values stored in ram.

Shoot an email to the SigmaDSP group (its on that website) seeing how they may be able to help you.

What you need depends specifically on what you trying to do? Music instrument related? Audio? The SigmaDSP is real easy, and geared more towards the instrument and consumer audio stuff.. Many music instrument effects equipments use it, many high end automotives use it (its good for room equalization as well).. I don't know if its ideal for the audiophile stuff (although few digital things are ;- ] ).. If you're trying to design the greatest component in a high end headphone amp chain you will need to do some good evaluation.. However hearing the apps engineer rock out on his guitar through the SigmaDSP, I must say it will fit many needs ;- ]

 

[threepointone]

NICE FIND! gotta try this myself sometime. The eval board datasheet really shows what this thing can do.

The eval board definitely is very expensive; it's $699. Add to cart in the part list, and you'll see it.

 

[_atari_]

Hi,

any body got interest designing a DAC around it?

I am currently thinking about designing a special headphone DAC:

- 24/96 USB Input (USB 2.0 Audio Spec) - most probably using some microcontroller

- SPDIF Input

- Asynchronous Upsampling

- WM8740 or AD81955 as output

- designed for desktop use

This DSP gives the oportunity to do some room simulation or bass boost or you name it in the digital domain. perhaps it is possible to program it in place - so that people can tinker with their dsp.

Would be great if anybody would like to contribute.

Cheers

_atari_

 

[threepointone]

It'd definitely be a great project, but let me just remind you that the DSP will mean that it'll require at least 3x more work to design than your usual audiophile DAC. Add the USB/microcontroller/SPDIF, and, well, it's even more work. If you're really going ahead with this, I'd recommend seeing if you could simplify it--from the eval board schematics, I think it might just be possible to implement USB, SPDIF, and everything with the DSP alone.

then you'd also have to work on the clocking / etc to make sure it's low jitter, audiophile quality, etc. . .

 

[hellomai]

so the whole thing is somewhat like this? :

USB controller SPDIF MicroProcessor
|| || ||
\/ \/ \/
----------------------------------------------------------
BUS controller
----------------------------------------------------------
/\ /\ /\
|| || ||
DSP memory other peripherals


and I would imaging you need an OS for all this.

 

[_atari_]

Hi,

yeah, I thought about it and it definitively is a lot of work.
The idea was to build a very good dac. The use of a DSP is perfect since you can do a lot of calculation in the digital domain without very much error (any purist will now kill me).

The basic idea is:

usb controller => DSP => upsample => DAC

I do not know if a bus is a solution, i can harbly imagine it since from my perspective it is a distinctive flow.

There are a lot of issues right now:
1) standard USB chips (PCM2702ff) are only capable of 48khz/16bit. 96lhz/24bit would be nice -> custom made solution!
2) many DACs (esp. the WM8740) have a built in attenuator that can or should be used. This must be controlled somehow and e.g. the controll must be embedded in the I2S stream -> FAST microcontroller
3) A DSP for e.g. room simulation is a good idea. This must be also wired to the frontpanel with a microcontroller

4) I do not want to talk about PCB design right now. Since with high speed digital circuits it is no fun at all!

I am currently planning to breadboard it at autumn. But I appreciate any help. The site "DAC Final has some very nice ideas!

 

[perfectturmoil]

That chip itself has its own DAC and ADC's built in. Decent ones, if I remember correctly.

That chip is fairly plug and play - you need to figure out how and what you need out of it (in terms of messing with the eval board (or maybe a custom design) and then burning the chip) and then you just dump an analog signal in and an analog signal comes out... As long as you have the peripheral circuitry correct..

I believe the SigmaDSP's processor is available as a stand alone product as well... So if you want your own DAC and ADC, look at that.. However, don't forget that Analog Devices is the world leader in high performance converters.. So do a good evaluation of whats in there before deciding you can come up with something better (cause I'm sure it'd be a bunch more work :- ] )

 

[_atari_]

Quote:

Originally Posted by perfectturmoil /img/forum/go_quote.gif That chip itself has its own DAC and ADC's built in. Decent ones, if I remember correctly. I believe the SigmaDSP's processor is available as a stand alone product as well... So if you want your own DAC and ADC, look at that.. However, don't forget that Analog Devices is the world leader in high performance converters.. So do a good evaluation of whats in there before deciding you can come up with something better (cause I'm sure it'd be a bunch more work :- ] )

Yeah, that is right!

I know that AD is doing some nice DACs. But you know - you want to get best of breed - allways. But If I got some time I will dig through the datasheet to get a better grip what is in the package and what not.

A separated DAC can be a better solution - you can choose components you believe to be better and you can choose some design you assume to be better than that done by the engineers at AD.

Perhaps using solely th DSP is a better idea since I do not need an ADC and designing an decent ADC is no easy task at all.

Lets see.

Anybody got some interest in some project like this?