It is the latter, which is what you are looking for. However, you may have another issue... Besides the S/PDIF switch, which engages ot bypasses the comparator, there is also DIP switch #1 which selects S/PDIF or I2S input. It also requires a reset to be acknowledged. The circuit wasn't designed to be switched between the two modes on the fly.
Re: Buffalo SPDIF\I2S Switch
What you want to do is actually possible, but you would need some custom firmware.
You can actually use the SPDIF input (comparator input) not just for SPDIF, but also for I2S or DSD (it is essentially a level shifted D1). That would avoid having to rig anything to switch physically on the buffalo. You could just leave the SPDIF switch closed in that case.
The firmware would need to switch between SPDIF input mode and PCM/DSD mode. Still that is pretty easy to do.
Personally I would recommend simply using a SPDIF MUX.
Cheers!
Russ
chobint said:
What you want to do is actually possible, but you would need some custom firmware.
You can actually use the SPDIF input (comparator input) not just for SPDIF, but also for I2S or DSD (it is essentially a level shifted D1). That would avoid having to rig anything to switch physically on the buffalo. You could just leave the SPDIF switch closed in that case.
The firmware would need to switch between SPDIF input mode and PCM/DSD mode. Still that is pretty easy to do.
Personally I would recommend simply using a SPDIF MUX.
Cheers!
Russ
Well Russ' idea sounds perfect, but is way over my head. And modifying my original plan to include a reset button every time you switch sources seem a bit clunky.
I'm thinking I will either simplify things by using the USB module's SPDIF output, since you guys noted no apreciable benefit to I2S. That way I could just use an OTTO or MUX in its most basic intended form. Or perhaps I will be patient and see how the AC1 and **potential** 24/192 firewire module concepts unfold before I do anything elaborate
Thanks for the answers, very helpful
I'm thinking I will either simplify things by using the USB module's SPDIF output, since you guys noted no apreciable benefit to I2S. That way I could just use an OTTO or MUX in its most basic intended form. Or perhaps I will be patient and see how the AC1 and **potential** 24/192 firewire module concepts unfold before I do anything elaborate
Thanks for the answers, very helpful
Hi!
Off-the-self Buffalo/IVY sounds very very good, but if you are going for the top sounding DAC I recommend to play with different I/V's. I experimented a lot...
Lately I've implemented Sabre volume control/LCD via RC5 remote (using PIC)... and just now I've implemented 192/24 I2S input via ethernet/FPGA.
Tests pending...
I need to get more 192kHz masters... does anyone have some?
Thanks,
Matej
Off-the-self Buffalo/IVY sounds very very good, but if you are going for the top sounding DAC I recommend to play with different I/V's. I experimented a lot...
Lately I've implemented Sabre volume control/LCD via RC5 remote (using PIC)... and just now I've implemented 192/24 I2S input via ethernet/FPGA.
Tests pending...
I need to get more 192kHz masters... does anyone have some?
Thanks,
Matej
matejS said:
Interresting!
Similar to the Linn devices http://www.linn.co.uk/digital_stream_players
?
Tell us more!
-rk
Hi!
I've bought a FPGA board w/ ethernet controller (to save resources on FPGA).
Then I've implemented ARP, ICMP (echo) UDP protocols on FPGA, connected OpenCores I2S core to Altera Avalon bus.
On client side (computer) I've implemented UDP sender program (for now it reads RAW files).
Some work has been done on buffering, flow control since 24/192 requires > 1MB/s.
... and it sings now
Linn devices are really nice, but also really $$$.
Matej
I've bought a FPGA board w/ ethernet controller (to save resources on FPGA).
Then I've implemented ARP, ICMP (echo) UDP protocols on FPGA, connected OpenCores I2S core to Altera Avalon bus.
On client side (computer) I've implemented UDP sender program (for now it reads RAW files).
Some work has been done on buffering, flow control since 24/192 requires > 1MB/s.
... and it sings now
Linn devices are really nice, but also really $$$.
Matej
Hi, Spartacus!
I've trued different op-amps and found LME47910 very good (it brings more enjoying atmosphere and deeper soundstage) - but it needs lots of break-in time. For decoupling I use Panasonic FM (they are really good for the price). I suggest to use THD4032 on I/V (yes, 2 per channel - inverting config per +/- branch) and then LME for S/E conversion.
A little bit better alternative is to replace I/V stage w/ something simpler (and not feedback). I can't tell how (my friend asked me not to spread that info - to let designers to play a little bit).
The ultimate is to go discrete...
Cheers,
Matej
I've trued different op-amps and found LME47910 very good (it brings more enjoying atmosphere and deeper soundstage) - but it needs lots of break-in time. For decoupling I use Panasonic FM (they are really good for the price). I suggest to use THD4032 on I/V (yes, 2 per channel - inverting config per +/- branch) and then LME for S/E conversion.
A little bit better alternative is to replace I/V stage w/ something simpler (and not feedback). I can't tell how (my friend asked me not to spread that info - to let designers to play a little bit).
The ultimate is to go discrete...
Cheers,
Matej
Buffalo Sales
The Buffalo DAC will go on sale this Friday (Sept 12) and Saturday (Sept 13). I will make half of my current inventory available each day. This is the schedule, designed to help with various timezones:
Friday, Sept 12 @ 8:00PM EST (12:00AM GMT)
Saturday, Sept 13 @ 8:00AM EST (12:00PM GMT)
If you know of people who are interested, please let them know.
As always, we will be trying to keep them in stock as much as possible. I have twice as many on hand as the last time around, so we will see how long they last.
The Buffalo DAC will go on sale this Friday (Sept 12) and Saturday (Sept 13). I will make half of my current inventory available each day. This is the schedule, designed to help with various timezones:
Friday, Sept 12 @ 8:00PM EST (12:00AM GMT)
Saturday, Sept 13 @ 8:00AM EST (12:00PM GMT)
If you know of people who are interested, please let them know.
As always, we will be trying to keep them in stock as much as possible. I have twice as many on hand as the last time around, so we will see how long they last.
Re: Counterpoint
Its coming very soon. I know its been a long time since I started this design, but it will come I promise.
I have tested the cct. It works.
I will be getting the first rounf of production PCBs very soon, I have just been waiting for things to get back underway in full swing here at Twisted Pear.
Brian has been very busy with other things, so I have not wanted to push out a bunch of new stuff.
Cheers!
Russ
Hi Danny,danny_66 said:
Its coming very soon. I know its been a long time since I started this design, but it will come I promise.
I have tested the cct. It works.
I will be getting the first rounf of production PCBs very soon, I have just been waiting for things to get back underway in full swing here at Twisted Pear.
Brian has been very busy with other things, so I have not wanted to push out a bunch of new stuff.
Cheers!
Russ
mikelm said:
Well I only cobbled together one channel to check for stability etc. So I really have not been able to listen to it, but for a single channel it sounds very good.
Also the test cct was very very basic, and I set it up for a lower current output DAC(PCM1794A) so I could use smaller(and fewer) Qs. I also did not use all of the cascodes. So the final cct should actually be better.
I can't wait to hear it in stereo.
Cheers!
Russ
Buffalo + CD PRO + Tent - Gosh
I think my intense dislike of the CD sound has just been removed.
I managed to get a Buffalo + IVY as mentioned earlier and tried to drive it from a Philips CD PRO (from Nico Thevissen, great guy) which I modded as per Nico's insructions to use the Tent clock.
Well, I plugged in the Buffalo (SPDIF) and it took ages to get a lock and then intermittently produced horrible clicks and scratches on top of the music, which didn't sound any better than my Mk1 RAKK DAC anyway.
Tried I2S and got horribly distorted sound out of one channel.
Brian very quickly responded to a cry for help with useful info + suggestions
CD PRO I2S isn't compatible with the Buffalo. Oh Dear.
After an hour of fiddling I reversed ground and SPDIF wires at the Buffalo input and the whole thing sprang into life.
The Tent module is transformer coupled with one side of the output (I guess) connected to ground via a 2.2K resistor so it's not totally floating and there's something about the signal polarity the Buffalo didn't like.
Unbelievable sound. I've got to work my way through my whole collection now but I'm listening to a Tracey Chapman CD that never sounded right before and now actually makes the hairs on the back of my neck stand up.
Well done the Twisted Pear!
I think my intense dislike of the CD sound has just been removed.
I managed to get a Buffalo + IVY as mentioned earlier and tried to drive it from a Philips CD PRO (from Nico Thevissen, great guy) which I modded as per Nico's insructions to use the Tent clock.
Well, I plugged in the Buffalo (SPDIF) and it took ages to get a lock and then intermittently produced horrible clicks and scratches on top of the music, which didn't sound any better than my Mk1 RAKK DAC anyway.
Tried I2S and got horribly distorted sound out of one channel.
Brian very quickly responded to a cry for help with useful info + suggestions
CD PRO I2S isn't compatible with the Buffalo. Oh Dear.
After an hour of fiddling I reversed ground and SPDIF wires at the Buffalo input and the whole thing sprang into life.
The Tent module is transformer coupled with one side of the output (I guess) connected to ground via a 2.2K resistor so it's not totally floating and there's something about the signal polarity the Buffalo didn't like.
Unbelievable sound. I've got to work my way through my whole collection now but I'm listening to a Tracey Chapman CD that never sounded right before and now actually makes the hairs on the back of my neck stand up.
Well done the Twisted Pear!
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