Hi all,
Recently we’ve become interested in building a DAC, and after spending a lot of time looking into design issues. We’ve decided to give non-oversampling DACs a go (As a cheap start into a never-ending process).
Being engineering students, the theory has never been a problem for us, but the lack of funds/time a student has means that we rarely get to do subjective development. If you could help us out with your experience with the TDA1541A, and get us started, it would be great.
Two questions for the TDA1541A fans:
Question 1
-----------
We know that some of you have tried many arrangements of using TWO TDA1541A DACs, including:
1) Parallel TDA1541As
2) Balanced TDA1541As with R+ and L+ on one, and R- and L- on the other.
3) Balanced TDA1541As with R+ and R- on one, and L+ and L- on the other.
In your opinion, and listening tests, which gives the best sound subjectively?
Question 2
------------
Can any arrangement of TWO TDA1541As equal a single TDA1541A S1 in sound?
Or will the single TDA1541A S1 always outperform two TDA1541As using the best arrangements for each ?
Basically we have a choice, we can either obtain a single TDA1541A S1 or two TDA1541A. We want to take the one from which we can obtain best sound (Applying all tweaks, arrangements, etc...). But the TDA1541A S1 is 3 times the price of 2 x TDA1541A.
Recently we’ve become interested in building a DAC, and after spending a lot of time looking into design issues. We’ve decided to give non-oversampling DACs a go (As a cheap start into a never-ending process).
Being engineering students, the theory has never been a problem for us, but the lack of funds/time a student has means that we rarely get to do subjective development. If you could help us out with your experience with the TDA1541A, and get us started, it would be great.
Two questions for the TDA1541A fans:
Question 1
-----------
We know that some of you have tried many arrangements of using TWO TDA1541A DACs, including:
1) Parallel TDA1541As
2) Balanced TDA1541As with R+ and L+ on one, and R- and L- on the other.
3) Balanced TDA1541As with R+ and R- on one, and L+ and L- on the other.
In your opinion, and listening tests, which gives the best sound subjectively?
Question 2
------------
Can any arrangement of TWO TDA1541As equal a single TDA1541A S1 in sound?
Or will the single TDA1541A S1 always outperform two TDA1541As using the best arrangements for each ?
Basically we have a choice, we can either obtain a single TDA1541A S1 or two TDA1541A. We want to take the one from which we can obtain best sound (Applying all tweaks, arrangements, etc...). But the TDA1541A S1 is 3 times the price of 2 x TDA1541A.
Unfortunately not, I never got the time, and those DACs are still sitting where I put them
If you're interested, take a look at:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=25608&perpage=15&pagenumber=1
I've posted some info here, but you'll have to work out a few things.
I'll post what I did, when I get around to doing it, hopefully soon...
(But plz don't wait)
If you're interested, take a look at:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=25608&perpage=15&pagenumber=1
I've posted some info here, but you'll have to work out a few things.
I'll post what I did, when I get around to doing it, hopefully soon...
(But plz don't wait)
I´ll wait. I have some TDA1541A (and some AD1865 etc) laying around for some time, because of the plan to build a balanced DAC ... but same as you describe.
The thread above i know, but i fell not skilled enough to work thing out. I´ll wait until someone posts a simple and working circuit for feeding the DAC right way for balanced operation.
The thread above i know, but i fell not skilled enough to work thing out. I´ll wait until someone posts a simple and working circuit for feeding the DAC right way for balanced operation.
till said:
Simple: one dac for L+ and R+ connected in the normal way.
other dac for L- and R- by inverting the dataline.
one dac for L+/L- and one for R+/R- here:
http://www.diyaudio.com/forums/showthread.php?threadid=8614&perpage=15&highlight=&pagenumber=1
I'm still looking at the output options, so no comment on 'sound' yet (i know it is taking loads of time with this thing...).
Regards,
till said:
Indeed lots of parts. But you can buy the pcb, so if you really want to get the TDA's working like this it is just a matter of buying pcb and the components. And yes, you need to find somebody to program the GAL (there is one obvious person to ask, i guess ....
) You could program the whole lot into one modern CPLD, but then you need to find somebody to do this with a programmer.
For DACs with parallel input, you need logic to convert I2S into parallel datastream = more parts. Early BB are parallel: PCM53, 54 and 55, but they are mono: you need four of them
If you want differential but with not so many parts: use the DACs in stereo and just invert the dataline to one of them.
The GAL has advantages: looking at the cambridge cd3 way of getting to 16Fs, i had a look if i could get 2Fs. It is possible with some reprogramming of the GAL (output DAC1: left sample & previous left sample, DAC2 right sample and previous right sample).
I sacrifised mute to switch into this mode (muting done with 7210). If it gets me anywhere, i dont know. But just to show that progr. logic has it's advantages.
Just to show off
:DAC
GUIDO BALTUS
CHIP GAL GAL20V8
LATCH GO WSDELAY SHIFT64 SHIFT32 DATA WS DIFFERENTIAL ONEFS CLKDIV2 CLKDIV4 GND
/OE NU1 DATAL WSL I2SCLK WSR DATAR FIFOREAD CLOCK CLOCK_INV NU2 VCC
EQUATIONS
FIFOREAD = /GO + GO * /CLKDIV2 * CLKDIV4 +
GO * CLKDIV2 * /CLKDIV4
CLOCK = CLKDIV4
CLOCK_INV = /CLKDIV4
I2SCLK = /CLKDIV4
WSL := ONEFS * /WS + /ONEFS * WS
WSR := ONEFS * /WS + /ONEFS * WS
DATAR := ONEFS * WS * DATA +
ONEFS * /WS * SHIFT32 * DIFFERENTIAL +
ONEFS * /WS * SHIFT32 * /DIFFERENTIAL * WSDELAY +
ONEFS * /WS * /SHIFT32 * /DIFFERENTIAL * /WSDELAY +
/ONEFS * /WS * SHIFT32 +
/ONEFS * WS * DATA
DATAL := ONEFS * WS * SHIFT32 +
ONEFS * /WS * SHIFT64 * DIFFERENTIAL +
ONEFS * /WS * SHIFT64 * /DIFFERENTIAL * WSDELAY +
ONEFS * /WS * /SHIFT64 * /DIFFERENTIAL * /WSDELAY +
/ONEFS * /WS * SHIFT64 +
/ONEFS * WS * SHIFT32
in case some people descide to do, i´m in. Alone i fear that i´m not skilled enough to solve the problems until it works.
simply connect one normal, and one with an inverter in sdata line? thats all?
this http://www.diyaudio.com/forums/showthread.php?postid=300953#post300953 looks more difficult
whats the drawback of this solution? does it also work with other DACs?
Another point: could you please give me a link to a TDA1541 datasheet? i can´t find it.
till said:
I did not have big problems with building the thing. One resistor missing at the reset ic, that was it. It's in the earlier post. But it is a lot more hassle than the one inverter. And it is NOT a complete DAC, no output circuits, no powersupply.
So my pcb does: Dac1: L+,L+ or L+,L-
Dac2: R+,R+ or R+,R-
depending on a jumper setting.
The inverter does Dac1: R+,L+
Dac2: R-,L- the one with the inverter on data
But the pcb is more than i2s split: also included is a fifo so the master clock can be in the dac (works with older philips/marantz players).
It should be possible to not have a fifo and take the incoming clock from i2s. That would mean no fifo, no buffer and no reset ic, i think. And some GAL reprogramming. Could look at this on request.
The other link shows a circuit for conversion from I2S to balanced 'parallel data in' as far as i could see with a quick view.
Indeed tda1541 only (also 1540 has (only) this mode, but that's 14 bit). Also possible i guess.
Regards,
Re: GAL
The original equasions are here: http://www.diyaudio.com/forums/showthread.php?threadid=8614&perpage=15&highlight=&pagenumber=2
They can be processed with opal (junior). I can post the file which can be used to program the GAL, no problem.
The equasions in this post (2fs mode included) are not tested. I just fiddled a bit so see if i could do this.
Reread the whole old threat if you are interested. If you still are, you can directly order the pcb at olimex. As far as i know there is one more pcb sold to a person in thailand. The poor guy is trying to get the components...
Greetings,
Andypairo said:
The original equasions are here: http://www.diyaudio.com/forums/showthread.php?threadid=8614&perpage=15&highlight=&pagenumber=2
They can be processed with opal (junior). I can post the file which can be used to program the GAL, no problem.
The equasions in this post (2fs mode included) are not tested. I just fiddled a bit so see if i could do this.
Reread the whole old threat if you are interested. If you still are, you can directly order the pcb at olimex. As far as i know there is one more pcb sold to a person in thailand. The poor guy is trying to get the components...
Greetings,
:
Hi
A balanced DAC is exactly what I would like to build.
I'm just ordering some parts !
after that the real fun will begin because I have absolutely zero knowledge of digital.
My aim would be to have R + L completely separate.
Also I will leave the o/p balanced as the rest of my system is already balanced.
I wonder if there is a good book that deals with the practicalities of digital that I could have a look at.
any suggestions ?
A balanced DAC is exactly what I would like to build.
I'm just ordering some parts !
after that the real fun will begin because I have absolutely zero knowledge of digital.
My aim would be to have R + L completely separate.
Also I will leave the o/p balanced as the rest of my system is already balanced.
I wonder if there is a good book that deals with the practicalities of digital that I could have a look at.
any suggestions ?
Because i don´t know much about DACs, the moste complicated circuit i dealt with are those until now: http://home.tu-clausthal.de/~tpa/
But ok, the most simple variant would be like this?
(should we ask a moderator to split threads as this isn´t "TDA1541A/S1 Arrangements" ?)
Attachments
till said:
Near enough except the inverter should be on the data line.
Not really it's all much the same thing be the dac a '41 or a '43 unless you opt for the simultaneous input mode.
Knowing about dacs wouldn't help that much anyway. You need some understanding of digital logic. Once you can visualise the data flow in your head, everything else is easy.
ray.
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