> > Date: Wed, 11 Jul 2012 10:16:48 +0100 > From: Dave Malham <dave.mal...@york.ac.uk> > Subject: Re: [Sursound] Waveplayer - 16 chnl SD-card audio device > To: Surround Sound discussion group <sursound@music.vt.edu> > Message-ID: <4ffd4480.2090...@york.ac.uk> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi Marc > On 11/07/2012 02:27, Marc Lavall?e wrote: >> Hi Dave >> >> Dave Malham <dave.mal...@york.ac.uk> a ?crit : >>> Hi Marc >>> >>> I've certainly thought about doing that, but not initially since it >>> means that >>> >>> (a) you would be limited to passive speakers >> This limitation is a feature: with less hardware the cost is lowered >> and the quality is raised. It would be a good choice to create small >> domestic systems or public installations. It would be adequate with 6 >> or more identical full range speakers. > Yes - and no. Different markets, I think... >>> (b) the specs aren't as good as the Analog Devices ADAU1966, the >>> evaluation board for which is sitting next to me :-) >> The better spec of the ADAU1966 is rarely matched by amps and >> speakers... I agree that for professional use it would be perfect. ;-) > True, but I am thinking about the "professional" market. Don't forget that > this project is driven by > my thoughts about the kind of jobs I'll be taking on after I retire. >>> (c) serious levels of hardware design needed for the power amps stages >> In the example application schematic the D-class amps with PWM inputs >> are connected directly to the PWM ouputs of the TAS5508C. How easier >> can it be? The final system could be made in the form of a PCM to PWM >> decoding board to connect amps with PWM inputs. > Yes, but given the level of currents (and voltages) concerned, this ain't > quite as easy as it seems > to get right. Been there, done that, got the burn marks on my fingers :-) >> >>> on the other hand, the TAS5508C has a "Full 8?8 Input Crossbar Mixer. >>> Each Signal-Processing Channel Input Can Be Any Ratio of the Eight >>> Input Channels." and "Mixer gain operations are implemented by >>> multiplying a 48-bit, signed data value by a 28-bit, signed gain >>> coefficient" so.... 8 speaker digital decoder, anyone? Only problem >>> is, no way to implement shelf filtering :-( >> Interesting! >> But its only job would be to interface PCM streams to PWM inputs. > Depends on the computing power of the thing doing the playback. > > Anyway, I will keep this under review.
see if you can get your head around Zetex DDFA..... http://www.diodes.com/_files/free_pages/u_0_lnk_090413235508.pdf This has very clean amps and some spare biquads, if you can find suitable signal paths for shelf filtering..... Geoffrey _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
