How to implement an AD8561 comparator in a DAC?

kittaylor · 15th September 2004, 05:18 PM

Can this be done with just the AD8561 at the DAC end and no mods to the transports?

I ask because I'm using it with a single +5v supply before a CS8412 and can't get it to work. With this configuration (which seems to have gotten the +ve and -ve inputs the wrong way rounf) I hear only silence, and hooking the signal to pin 2 and putting a 100R to ground on pin 3 I get a very quiet analogue output with lots of distortion.

Thanks if you can help.

kittaylor · 17th September 2004, 10:52 AM

Anyone?

greyhorse · 17th September 2004, 12:18 PM

Yes, Elso's comparator input mod does work without changing anything on the transport end. Probably, just not in the way you have it connected. I've followed Elso's schematic exactly, and got excellent results. Using a single supply is also not a problem as that is what I'm doing too.

Are you using RXN for another input or something? Re-read the transport thread to find why Elso has the AD8561 connected the way he does.

the schematic:
Digital transformer

kittaylor · 17th September 2004, 03:39 PM

Looks like I'll have to give it another go.

What should be done with RXN when only RXP connects to the AD8561? Cap to ground as in the CS8412 dataheet?

Does the schematic with -ve and +ve supplies work with just the one +5ve supply, and if so what should be done with pin 3? Connect to ground?

TIA

greyhorse · 17th September 2004, 08:58 PM

Yes, the schematic with dual supplies works with only a single supply. Just connect pins 4, 5 and 6 to GND. The same thing can be done with pin 3, which is what I did. Alternately connect it to GND thru a 100 ohm resistor.

If you're not using RXN for another input, you should connect it to pin 7 of the comparator. If you insist, sure, connect it to ground thru a 0.01uF capacitor. Just keep in mind that you won't get the full advantage of the mod.

15th September 2004, 05:18 PM	#1
kittaylor diyAudio Member Join Date: Apr 2004 Location: Here	How to implement an AD8561 comparator in a DAC? Can this be done with just the AD8561 at the DAC end and no mods to the transports? I ask because I'm using it with a single +5v supply before a CS8412 and can't get it to work. With this configuration (which seems to have gotten the +ve and -ve inputs the wrong way rounf) I hear only silence, and hooking the signal to pin 2 and putting a 100R to ground on pin 3 I get a very quiet analogue output with lots of distortion. Thanks if you can help.

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17th September 2004, 10:52 AM	#2
kittaylor diyAudio Member Join Date: Apr 2004 Location: Here	Anyone?

17th September 2004, 12:18 PM	#3
greyhorse diyAudio Member Join Date: Feb 2002 Location: Ontario	Yes, Elso's comparator input mod does work without changing anything on the transport end. Probably, just not in the way you have it connected. I've followed Elso's schematic exactly, and got excellent results. Using a single supply is also not a problem as that is what I'm doing too. Are you using RXN for another input or something? Re-read the transport thread to find why Elso has the AD8561 connected the way he does. the schematic: Digital transformer

17th September 2004, 03:39 PM	#4
kittaylor diyAudio Member Join Date: Apr 2004 Location: Here	Looks like I'll have to give it another go. What should be done with RXN when only RXP connects to the AD8561? Cap to ground as in the CS8412 dataheet? Does the schematic with -ve and +ve supplies work with just the one +5ve supply, and if so what should be done with pin 3? Connect to ground? TIA

17th September 2004, 08:58 PM	#5
greyhorse diyAudio Member Join Date: Feb 2002 Location: Ontario	Yes, the schematic with dual supplies works with only a single supply. Just connect pins 4, 5 and 6 to GND. The same thing can be done with pin 3, which is what I did. Alternately connect it to GND thru a 100 ohm resistor. If you're not using RXN for another input, you should connect it to pin 7 of the comparator. If you insist, sure, connect it to ground thru a 0.01uF capacitor. Just keep in mind that you won't get the full advantage of the mod.

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