TAS5706 simple full digital stereo amplifier

[iampivot]

You seem to be on a roll here.

You believe your TAS4i sounds better, might it be because it has better jitter suppression, or just due to the output stage being different?

How about adding a USB audio input in addition to spdif, or use a SRC4392 as you suggested?

Also, how about adding a digital volume pot, should be easy to do with some PIC code?

[KOON3876]

Originally posted by iampivot
You believe your TAS4i sounds better, might it be because it has better jitter suppression, or just due to the output stage being different?
How about adding a USB audio input in addition to spdif, or use a SRC4392 as you suggested?
Also, how about adding a digital volume pot, should be easy to do with some PIC code?

Hi I tested now,
(a) single channel, TAS-4i (TAS5518+TAS5142)
(b) TAS5706
... and I'm not sure I can pass blindfolded test. TAS5706 is worthy adversary with LINN Acurate212.
(a) pros: Power supply voltage control.
(b) pros: closed loop. newer design?

TAS5706 board has external I2S input, so if I have time I can try something other than CS8416.

Last night I posted initial version PIC source code, with volume control and input selection, to my website.

[jkeny]

Fantastic work Koon,
I'd be very interested in how the I2S input sounds - supposedly cleaner/sharper/clearer than SPDIF

Both this & USB input could be achieved with PCM2706/7 USB chip

Are you using the same variable PS vol control as used on the TAS-4i?

Any idea of offering a group buy of boards when project is finished? This would give something back to you for all the work you are putting in & allow interested (but not as competent as you ) DIYers, like myself, to build something similar!

Edit: I'm currently modding the guts out of a Panasonic SA-XR57 multichannel amp based on the TAS5076/TAS5182 Equibit chips. Would love to build one of your TAS5706 amps as a reference to compare against & as a great 2 channel amp! Panasonic class D amps

[KOON3876]

Originally posted by jkeny
Are you using the same variable PS vol control as used on the TAS-4i?
Any idea of offering a group buy of boards when project is finished?

Hi thanks for interest,

TAS5706 does not require variable voltage, it takes 10-26V range fixed. Now I'm using $199 Lab DC supply, 18V/3A, as 12V ps.

I will try to connect I2S later, from my SD card player, and USB I2S device. ...By my SD card player, I can try whole DIY full digital, no AC, no motor audio system

For group buy,, just a while until I order box & satisfied for inspection. I have 2 boards so I can send 1 to someone.

Then I need someone who could
(1) re-inspect. at least measure THD/N, temparature, waveform.
(2) re-make. order sample board / parts / assemble / listen.
by these step you can think this amp is reproductive.
(3) manage group buy. too much job for me.

[jkeny]

Hi Koon,
I would be interested in the spare board if I pay you + shipping - I'll PM you.

I have a 100MHz osc but haven't used it yet - I'd have to get up to speed in using it to do some measures but I'm willing.

Edit: I can see this amp being very popular to the DIY community so a group buy will probably be very appreciated!

[KOON3876]

Hi jkeny
don't be so upset... this amp's birthday is just 1 week ago.
I have parts for spare board, so initial tester will receive completed one, at free. no money required but...

I hope initial tester can,
measure THD/N with some frequency / output watt
look wavesforms around circuits, and judge against datasheet
measure thermal temparature at high watt usage
re-program PIC when I updated firmware
point out improvement on schematic / board

it will take about 1-2 weeks until I get enclosure and panel, misc parts, listen many CDs, measure around.

[KOON3876]

I posted THD+N result to my site,
1kHz 4W < 0.1%.
(please see site for detail)
good point is very low 3rd distortion.

>jkeny
anyway please wait until I finish 2nd board and enclosure.

[iampivot]

Originally posted by KOON3876
anyway please wait until I finish 2nd board and enclosure.

I'm very interested, I've already ordered a few TAS5706 samples.

Could you consider adding a digital volume pot to the board?

[KOON3876]

Originally posted by iampivot

Could you consider adding a digital volume pot to the board?

Hi, what is "digital volume pot" you mean?
TAS5706 contains digital volume and I'm controling it by PIC.
just writing volume value to TAS5706 0x07 register.

[iampivot]

Originally posted by KOON3876
Hi, what is "digital volume pot" you mean?
TAS5706 contains digital volume and I'm controling it by PIC.
just writing volume value to TAS5706 0x07 register.

Just an optical rotary switch, eg something like http://search.digikey.com/scripts/Dk...D-E28-L064N-ND

Each clockwise click would generate an up impulse, and counter-clockwise would generate a down impulse. The PIC code could simply update a counter and write the register. This is similar to how the volume wheel on a tact M2150 works.

A bit more detailed: http://www.circuitcellar.com/library...52/2303017.pdf

A thread with some info here: PGA2310 Digital Volume Control