Anyone used an STA323W Amp?

[dpuopolo]

Has anyone used the ST Microelectronics STA323W amp chip?

A company I consult uses these in one of their products and they sound great!

They run it as a 25 watt/channel stereo amp, but it can be used other ways too.

Here's the data sheet:

http://www.st.com/stonline/products/...e/ds/11535.pdf

[tylerjbrooks]

I took a look at this family of amplifiers about a year ago but I ended up settling on something else (TAS5504 + TAS5142 from TI). Mainly because I wanted more processing options and power.

The TAS5xxx and the STA3xx families seem to have about the same THD+N numbers. They both suffer from being open-loop systems so they have low power supply rejection (or so I am told).

But, to my ears, they both sound fine and I like that they are easy to use. Lets me concentrate on other aspects of my system.

Anyway... I ordered an evaluation board for the STA326 (a little higher power than the STA323) and it took them a loooong time to send it. Too long. By the time the postman dropped the eval board on my door, I had already decided on something else.

If you like, you can have my eval board. Just pay for the shipping (I live in Seattle). I guarantee it will be faster than trying to get one out of your local rep. Send mail if you want it.

Tyler.

[Neil Davis]

Originally posted by tylerjbrooks

If you like, you can have my eval board. Just pay for the shipping (I live in Seattle). I guarantee it will be faster than trying to get one out of your local rep. Send mail if you want it.

Tyler.

I'm not the original poster, but if you let me have the board I will get it back to you (eventually) with some nice code to control it. Take a look at the preliminary code in the link--that was done for the TAS3004. It allows you to read loudspeaker response files and use the biquads to develop crossovers and EQ. This code controls an amp like the one in the picture by sending the coefficient and register data across the USB bus (the power amp is the AD1994). The board can save the data in memory on the amp, so once you use the Windows app to develop the crossover and EQ the amp can program itself. The code in the link isn't fully functional, but it can change the biquads in real time, and switch between two banks of stored coefficients.

I've got another version of this application that controls the Apogee DDX-8001 chip (STA308). It's working and is actually a bit further along than the TAS3004 version. It also generates the coefficient data for the biquads from the filter specs and controls the chip registers, so adapting the code to the STA323 should be easy. I'd like to have the routines for the STA323 working, so I just need like to borrow your board until I can get around to making my own boards.

I like the STA32X chips. There are more advanced alternatives now, like the TAS5706 and Cirrus CS4525 and the AD1953/AD1994, but for some applications the STA323/6/8 would be a great solution. I'd like to have one software application that controls all of the 2-3 channel chips, plus another one for the 6-8 channel chips such as the TAS5518 and STA309.

The code requires the .NET framework and you must have the manco.dll file in the same directory (that dll handles the charting). BCD code for TAS3004 amps

BTW...I'll probably be in Seattle in two weeks.

[tylerjbrooks]

I haven't heard from DP yet but it has only been a couple of days. I think it is only fair to wait until next week or so to see if he wants it.

You are second in line if he doesn't want it.

I would be interested in the biquad code. Sometime in the future, I would like to bi-amp some speakers with my system. I had it in the back of my mind to use the biquads to fix the obvious imperfections in the speaker response.

My partner has finished an ALSA driver (linux sound driver) for the TAS5504. I am sure he would be interested in how to use the biquads to equalize speakers. I will try to get him to post his work on our site.

Coming to Seattle? If so, maybe I could just hand you the board.

O... one annoying fact about the eval board. It didn't come with any manuals. You have to figure it out on your own. The board has some labels (MCLK, BCLK, ...etc) and some analog inputs so I bet you can figure it out. Alternatively, scrounge around on the ST site and see if you can find some info on it. It is an 'AP Interface' card that biggy-backs onto the actual amplifier board (a STA236_8 2.1Ch board VER 0 FEB 7 2006).

[dpuopolo]

Let Neil have it, that way we'll all benefit.

[tylerjbrooks]

OK Neil. It is all yours.

Hit me with some email and we can work out how to get it in your hands.

[Neil Davis]

Originally posted by tylerjbrooks
OK Neil. It is all yours.

Hit me with some email and we can work out how to get it in your hands.

Email sent.

I posted some info on how the STA32X fits into my plans at the following:

Plateamps for active speakers

As you can tell, the STA32X is one of many options I'd like to make available for building active speakers. I've got a number of these amps working, but there's still a lot of work to be done to make them a "product". However, the software was a long pole, and I've made a lot of progress on that recently

[jonsmirl]

Neil, I checked out your slide presentation. You are building something similar to our (Tyler and me) Digispeaker, http://www.digispeaker.com, project. Tyler has the STA326 eval board because it is an amp we evaluated and decided not to use.

Digispeaker takes your concept up another level. A Digispeaker needs digital input. It has a powerline modem and can receive this input over the AC wiring in your house. The digital source can be Internet radio, your PC, an A/D input board, or another Digispeaker (they have internal SD cards to hold the music).

The current Digispeaker design supports two models - a low end one which can biamp a pair of speakers and takes 44.1/48Khz input. Or a high end mode where you use two triamped Digispeakers (L/R) and they accept 192/24 input. The amp is a TAS5504 with a TAS5342 output stage.

Digispeakers are networked and work as a synchronized multiroom audio system. In the high end configuration you put two in each room and they are synchronized on left/right channels.

If you poke around on the web site you see that we support Insteon. Insteon lets you replace an existing light switch with a Keypadlinc, http://www.smarthome.com/2486dwh8.html. Buttons on this control the audio source, volume, etc. and your light too. The system is also capable of being controlled by an iPhone/iPod touch or any other IP device.

The full design is on the website. Take a look and let us know what we can do to improve it.

[Neil Davis]

Originally posted by jonsmirl
Neil, I checked out your slide presentation. You are building something similar to our (Tyler and me) Digispeaker, http://www.digispeaker.com, project.

I looked at your web site, and what you are doing is interesting, but my focus is quite different. I'm more interested in active speakers with built-in digital crossovers, and that is why I need multiple amps and why I'm taking advantage of the biquads. Biquads are a great way to make great crossovers. The presentation is actually part one of two: the possibilities get more interesting with the 6-8 channel amps like the TAS5518 or STA309. Right now I'm working on a very interesting speaker that uses two of the Spherex Xbox amps. The Spherex amps use the DDX-8001 controller--basically the same as the 8-channel STA308.

There is a much older briefing that outlines where I was heading with these amps several years ago and provides some background. Actually, I'm still following the same basic plan: http://home.comcast.net/~neilandbarb...kers/N-way.ppt

I agree with the benefits of an all-digital signal path, but I'm not commited to it. The digital amps require a well-designed power supply, because they are basically a power DAC. Also, you can still get lower distortion with a Class-D amp that has a well designed feedback loop. So in addition to the all-digital amps I'm also looking at digital amps that have analog inputs such as the TDA8290 and the AD1994.

Another difference we have is that I'd rather keep the audio networking "open" to allow different solutions. I agree that the powerline audio is a good approach, but so is wireless and wired ethernet. A lot of vendors are coming out with digital media players that you will be able to buy cheaper than you or I could build them, so why not have this be an off-the-shelf module that can be used with standard media server software? For this multi-amp speaker I'm working on I was leaning toward the Zyxel DMA1100P media player, but I haven't gotten that far yet.

BTW, the powerline audio concept is not new: the first wave came and went without commercial success. STT came out with the homeplug audio systems several years ago (see http://www.stt.com.tw/product/spk85.html), although they didn't try to address the high-end market with a full digital path. I've got 3 or 4 of the receiver boards that I scavanged from the Radio Shack Accurian HomePlug speakers, which were a commercial flop. I've also got a transmitter--you are welcome to all of them. The receivers and transmitter are actually the same board with different firmware, and they use the older Intellon 5100 chip (along with MP3 compression to reduce the data rates). It works OK in my house, but I couldn't get it to work at my mom's apartment complex because there were too many dropouts. The 5500 chip should be more robust and the 200M AV chips should be even better, but it's worth noting that powerline audio may not work unless you have an interference-free line.

But even though we have different objectives, we should probably continue to compare notes and look for opportunities to collaborate. About a year and a half ago I set up the Audio Developers web site, but I haven't done anything with it. The concept was to have a single site where multiple developers could sell or share complementary capabilities, such as electronics, software, cabinets, crossover design, measurement services, etc. A key idea was to get members of this "collective" to talk to each other to look for ways they could help--and this could be shared software, PCB design services, or other intellectual property that could help members be successful. If this is interesting to you maybe I need to get this effort organized.

My plan two years ago was to retire and start doing this fun audio stuff for work, but I'm married, and my wife had different ideas. The up side is that we have a nice house in the country...the down side is that I'm still working at a 9-5 job to pay for it.

[jonsmirl]

The presentation is actually part one of two: the possibilities get more interesting with the 6-8 channel amps like the TAS5518 or STA309.

Why do you need more channels? The TAS5508 only has three fully capable channels. So does the TAS5518. Those extra five channels don't work at 192Khz. I see from your older project you were trying to drive a dozen speakers.

We are using the three full channels to tri-amp in 192K mode with two Digispeakers (one for L/R). For lower cost use a single one and it can bi-amp at 44.1/48. It can also drive two full range speakers at 192K. The TAS5504 has the biquads needed to do this.

Note that you could use 10 Digispeakers in one room each capable of driving three speakers. You can then program the biquads to drive each speaker anyway you want to. Send 1Khz bands to each speaker, etc.

Digispeakers can take a 7.1 AC3 stream in and pick off individual channels. The mpc5200 CPU can do 1GFLOP and mp3 decoding takes less than 10% of the CPU. ac3 decode takes about 25%.

We're getting ready to start looking at speakers. We need to locate ones that are matched to our amps capabilities.

The digital amps require a well-designed power supply, because they are basically a power DAC.

Power supply is a 90W, L6599 based half-bridge LLC adaptor with very stable output voltage and low EMI. It has a power factor correction front end (L6563 based) so it complies with the most stringent regulations. It's 92% efficient at full load. Power supply volume control is also implemented. This is a complex power supply to design.

What would be an alternative amplifier with a feedback loop?

Another difference we have is that I'd rather keep the audio networking "open" to allow different solutions.

The boards have Ethernet on them too. It can be let unpopulated to reduce costs ($8).
There is also a USB jack which can be populated ($5). Plug an 802.11 wireless stick into it.

A lot of vendors are coming out with digital media players that you will be able to buy cheaper than you or I could build them, so why not have this be an off-the-shelf module that can be used with standard media server software?

The boards have a SD card socket. They understand SDHC and can take 8GB+ plus cards. To your PC they just look like remote disk drives. Copy your tunes into the SD cards and now you don't need a media server. The Digispeakers know about each other and can play tunes located on other nodes. Of course we can source from a media server or stream too.

If you want to play vinyl, digitize it first. Use a 192/24 DAC. Won't wear out your vinyl this way.

Powerline works OK in my house, but I couldn't get it to work at my mom's apartment complex because there were too many dropouts.

The 85Mb is more noise resistant that the older 14Mb.

To get around drop outs, the nodes use the 85Mb net to stay ahead of the stream. For example they may copy the next 4-5 songs on the play list into RAM on all of the nodes before synchronously starting to play them. Same for a net stream, it get buffered and then synchronously played. You can turn this off for live events.

In general the music is not streaming around the net in real-time. It moves around faster than real-time and highly synchronized clocked are used to make everything play at the same time.

If it is really a problem switch the node to Ethernet or 802.11.