In my Rotel 965 cd player there is a 47uf cap per channel directly in the signal path coming out of the DAC (SAA7323) This leads to the output stage followed by 2 more caps 100uf (all are blackgate type F). I know the 100uf are for DC blocking. What are the 47uf for? The same? (guess nothing more). Here is the daatsheet for the SAA7323:
http://www.docethifi.com/saa7322-7323.pdf
At the end is a app note that features the same 47uf on the output of each channel. Even though these are blackgate (not wishing to start any arguments about blackgate merits or not) no cap is better than any cap if not required. So are these required? Please could someone with more knowledge comment on this for me?
http://www.docethifi.com/saa7322-7323.pdf
At the end is a app note that features the same 47uf on the output of each channel. Even though these are blackgate (not wishing to start any arguments about blackgate merits or not) no cap is better than any cap if not required. So are these required? Please could someone with more knowledge comment on this for me?
hmm interesting. I thought it might be. Although the datasheet says the dacs output is maximally 1v - hence the output stage to make it 2v. Or so i assumed. I wonder what would happen if i removed.
1 volt is probably correct but refers to ac level, you can still have a 2.5v dc offset.
I would not remove them without understanding how the rest of the analog curcuit looks.
I would not remove them without understanding how the rest of the analog curcuit looks.
Actually thats the RMS figure. Doesnt seem to be that much data in the datasheet. from what i can gather the output can be -0.5v DC to 5.5v DC (0.5 above supply voltage at 5) Thnk it best to leave em there then - or upgrade em with soething better if they have to be there.
DC blocking cap
The cap is for blocking DC at the output. If you switch to a high quality opamp AD or BB part you should be able to get rid of the offset and you would not need the 47uf cap. That cap will only degrade the sound. Another option is to get a quality replacement cap and get rid of the crummy electrolytic cap.
Check this out on quality opamps
http://www.diyaudio.com/forums/showthread.php?threadid=19209&perpage=15&pagenumber=2
The cap is for blocking DC at the output. If you switch to a high quality opamp AD or BB part you should be able to get rid of the offset and you would not need the 47uf cap. That cap will only degrade the sound. Another option is to get a quality replacement cap and get rid of the crummy electrolytic cap.
Check this out on quality opamps
http://www.diyaudio.com/forums/showthread.php?threadid=19209&perpage=15&pagenumber=2
No sorry (jewilson) think u misunderstood - the opamp is on the DAC chip itself in this instance - bitstream philips part saa7323. The output from the DAC chip is not for IV conversion it has already been thru one opamp - probably an onboard 5532/34 at a guess. Nice. The cap as it happens is not that crummy and could only be improved upon using a better blackgate. (space wise) I was only wondering if the cap was needed before the second opamp (which is then followed by another Dc blokcing cap)
That for the de-emphasis circuit
Rotellian
Well it must be my sinus meds. I Look up pin 8 and thats the de-emphasis circuit. You can remove it as it work as a high cut filter. I've removed mine in my DAC. The circuit is only activated when the bit from SPIF is on. The emphasis is add 6.5dB of loss at 800Hz, who needs that.
Still I would consider replacing a 5532 or a 5534 opamp with somthing better and a Black Gate cap to replace the 47uf would improve the sound.
Rotellian
Well it must be my sinus meds. I Look up pin 8 and thats the de-emphasis circuit. You can remove it as it work as a high cut filter. I've removed mine in my DAC. The circuit is only activated when the bit from SPIF is on. The emphasis is add 6.5dB of loss at 800Hz, who needs that.
Still I would consider replacing a 5532 or a 5534 opamp with somthing better and a Black Gate cap to replace the 47uf would improve the sound.
Im still not sure if I can remove this safely or without introducing 'problems'. Maybe i should just try it.
The first cap is probably to remove the DC offset from getting to the output stage. The second one is probably to keep DC from the output of the unit. I assume the op-amp on the output is running with Plus and Minus rails, so as long as this stage is referenced to ground, you probably don't need the last cap. However, It also keeps the output from going to the rail when problems occur. As long as the op-amp never fries, you may be alright.
- Status
- Not open for further replies.