Got my opus dac working last night. My system is in a state of flux, so it's hard to do a meaningful evaluation, but it certainly sounds nicely transparent. I hope to try it in a friend's system soon in order to make further analysis of what it is doing sonically.
Russ/Brian, how are the ASRC boards progrssing?
Dan
Russ/Brian, how are the ASRC boards progrssing?
Dan
We went ahead and ordered some ASRC boards they should be here any day. That board is called the "Metronome" If they work out alright then I will purchase stencils etc so we can offer them regularly. For now we may go ahead an offer a few to some people. But it is not easy to make these boards without a stencil, and we don't like to order stencils until a design is proven. 🙂
We also ordered some other goodies. Including a tiny inexpensive Toslink input board which we will work with our SPDIF receivers (either one). The rest of the new designs we are keeping under our hat for now.
Cheers!
Russ
We also ordered some other goodies. Including a tiny inexpensive Toslink input board which we will work with our SPDIF receivers (either one). The rest of the new designs we are keeping under our hat for now.
Cheers!
Russ
It's good to see the ASRC board is going forward. It looks to me that it might be useful in a variant of what Rossl did here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=95972 .
Even just routing the signals directly to an Opus would probably be worthwhile, but I'm hoping to route them through a PC for eq/xover etc. I just need to figure out how to get the resulting I2S into my PC without going through spdif - I *think* I can splice into my Delta 1010 breakout box (which would also give I2S output for the Opus boards), but I'm still looking at that.
Even just routing the signals directly to an Opus would probably be worthwhile, but I'm hoping to route them through a PC for eq/xover etc. I just need to figure out how to get the resulting I2S into my PC without going through spdif - I *think* I can splice into my Delta 1010 breakout box (which would also give I2S output for the Opus boards), but I'm still looking at that.
dwk123 said:
Ahh yes, very interesting project that one.
If I understand it correctly you could accomplish what Rossi does with our ASRC board and a our WM8804 transiever board. Our Wm8804 can take I2S in and output SPDIF (up to 192KHZ). You could actually not use the ASRC at all if you don't want to.
Cheers!
Russ
Russ White said:
Hmm, I'll have to look more closely. I thought after reading the datasheet I concluded that it would need programming to xmit as a master. Maybe it was only that it needed a different clock.
As a first step, this would be easy and therefore very attractive particularly since I already have it 🙂. Ultimately if it works I'd like to pull the full multichannel signal though, and 3 spdif lines isn't a very convenient form to work with.
True. My personal application involves a PC and FIR filters though, and switching filter banks every time the sample rate changes is a royal pain. Assuming the ASRC is done well, the benefit of being able to run with a fixed rate is worth the effort.
Beta Opus finally singing
Hi Russ, FINALLY my Opus sings. After months I now had the time for building the boards in a decent case. Results are very good regarding the highs and midrange. Soundstage is very good and depth and spatial imaging are on a high level. My Opus is somewhat bass shy. It is still breaking in so it might change in some days. Without any scientific explanation I simply suspect the OSCONs in the output circuit. I also experience some static clicks when the source starts feeding signal over SPDIF. They do not bother me really but I'll try to find what causes this.
Hi Russ, FINALLY my Opus sings. After months I now had the time for building the boards in a decent case. Results are very good regarding the highs and midrange. Soundstage is very good and depth and spatial imaging are on a high level. My Opus is somewhat bass shy. It is still breaking in so it might change in some days. Without any scientific explanation I simply suspect the OSCONs in the output circuit. I also experience some static clicks when the source starts feeding signal over SPDIF. They do not bother me really but I'll try to find what causes this.
Re: Beta Opus finally singing
Ah yes the original beta boards. 🙂 Very glad you got it going.
Are you still using a transformer for BAL -> SE conversion?
Also if you are using consumer SPDIF make sure you ground -IN, as this could be causing your clicks etc.
Cheers!
Russ
jean-paul said:
Ah yes the original beta boards. 🙂 Very glad you got it going.
Are you still using a transformer for BAL -> SE conversion?
Also if you are using consumer SPDIF make sure you ground -IN, as this could be causing your clicks etc.
Cheers!
Russ
Hi Russ, I designed a simple output stage for BAL -> SE with high quality amorphous core transformers but I have not had the boards made (yet). I really had other things to do the past months. Probably the specs of the DAC will be better when symmetric outputs both are used ?! Now I just use only one of the outputs for SE use.
What are your experiences with your BAL -> SE output stage ? And did you try other caps at the output instead of the OSCONs ?
Anyway, the older beta DAC is a fine product. Just wanted to let you know as the beta phase is history for some time now. I can only imagine how the final design sounds.
Regarding the advise to ground the -IN: did you also connect the case to the DACs ground or did you leave it floating ?
What are your experiences with your BAL -> SE output stage ? And did you try other caps at the output instead of the OSCONs ?
Anyway, the older beta DAC is a fine product. Just wanted to let you know as the beta phase is history for some time now. I can only imagine how the final design sounds.
Regarding the advise to ground the -IN: did you also connect the case to the DACs ground or did you leave it floating ?
Attachments
I am still using the Beta full time (embedded in my CD player).
I leave my ground floating. For -IN, the CS8416 receiver board now has an onboard jumper to ground for single-ended S/PDIF use.
If your system can tolerate some DC offset, you could try bypassing the caps to see if it eliminates the bass problem. I have thought about some off-board (large) 20-22uF MKPs, but have not tried it, as I haven't really found the need in my system.
I leave my ground floating. For -IN, the CS8416 receiver board now has an onboard jumper to ground for single-ended S/PDIF use.
If your system can tolerate some DC offset, you could try bypassing the caps to see if it eliminates the bass problem. I have thought about some off-board (large) 20-22uF MKPs, but have not tried it, as I haven't really found the need in my system.
Hi Brian, the output transformers I want to use are allergic for DC. I think I will settle for Black Gate N series caps if they will fit. If not I have to adapt the transformer PCB so the caps will find their place on that PCB.
Hi JP,
I think I have a good solution for you if you wish to try it. If you look at the "Ballsie" schematic you will notice the stage that does the BAL -> SE conversion regjects common mode voltage. So the SE output (only!!!) will have virtually no DC component. You would completely omit (or bypass with a jumper) the output caps of the DAC if you used such a circuit. Just keep in mind the balanced outputs of the ballsie will still have the 2.5V common mode voltage, only the SE output will not.
If you wish to roll your own SE conversion circuit the first part of the ballsie circuit can easily be omitted, just increase the values of the resistors around the opamp to keep the impedance > 2K or so. I would shoot for 2.21K.
For capless DC free balanced output our TXD board fits the bill very nicely. You can use the TXD as a buffer/Line Driver with no cap on the DAC as the TXD also completely rejects the common mode DC.
So its quite easy to go capless if you want to. 🙂 But honestly the Oscons are excellent, and I don't think its the caps. I just wanted to be sure everyone knows there are tons of options. 🙂
Cheers!
Russ
I think I have a good solution for you if you wish to try it. If you look at the "Ballsie" schematic you will notice the stage that does the BAL -> SE conversion regjects common mode voltage. So the SE output (only!!!) will have virtually no DC component. You would completely omit (or bypass with a jumper) the output caps of the DAC if you used such a circuit. Just keep in mind the balanced outputs of the ballsie will still have the 2.5V common mode voltage, only the SE output will not.
If you wish to roll your own SE conversion circuit the first part of the ballsie circuit can easily be omitted, just increase the values of the resistors around the opamp to keep the impedance > 2K or so. I would shoot for 2.21K.
For capless DC free balanced output our TXD board fits the bill very nicely. You can use the TXD as a buffer/Line Driver with no cap on the DAC as the TXD also completely rejects the common mode DC.
So its quite easy to go capless if you want to. 🙂 But honestly the Oscons are excellent, and I don't think its the caps. I just wanted to be sure everyone knows there are tons of options. 🙂
Cheers!
Russ
BrianDonegan said:
I see the new receiver PCB has no SPDIF input transformer at all. Did the original input not put up with expectations or was this decided as a cost reduction ? Just curious.
I'll think about the options you and Russ offered for omitting the OSCONs. The transformer option is a nice one as there will be no active components (opamps) in the output. It could be the difference between "very good" and "excellent" 🙂
Till now I haven't measured the device for RF/HF at the output without filtering. Is filtering really necessary ?
Pardon me for questions about the beta DAC while the product is already out of beta status.... The device really is very good sounding as it is but I'd like to sqeeuze everything out of it that's possibly in it. Next test will be a comparison with Pedja DAC 1.1b which is a non oversampling TDA1541A DAC.
The WM8804 does not have differential input, so we omitted the transformer since it make much less sense without diff inputs, especially with most people using consumer gear. The good news for some folks is that we still offer the CS8416 board with SPDIF input transformer precisely because we know that for some folks it actually may be more desirable.
It is not a case of one being automatically preferred over the other, each has its strong points.
Cheers!
Russ
It is not a case of one being automatically preferred over the other, each has its strong points.
Cheers!
Russ
I have found in my experience that additional output filtering (while not seeming harmful to me) is completely unnecessary. I attribute this to the fact that the DAC already filters the output sufficiently.
Cheers!
Russ
Cheers!
Russ
Thanks, the project seems very succesful (certainly soundwise). I wish you both good sales and more good design ideas for the future !
Thank you, and I am very pleased you got it working. I actually use my original beta OPUS quite a lot.
Cheers!
Russ
Cheers!
Russ
