Hi guys,
Great that it doesn't hum, but a little more information on how it
sounds would be nice 😉
That, and some test data ...
EDIT: sorry, forgot to read Russ' post about the listening session.
M
Great that it doesn't hum, but a little more information on how it
sounds would be nice 😉
That, and some test data ...
EDIT: sorry, forgot to read Russ' post about the listening session.
M
Subjective post, you can safely ignore... 🙂
Ok since it has been asked, I will give you my opinion on the sound. Keep in mind I am anything but objective on this subject. I would really rather hear how some third party feels about it. 🙂
I have one other DAC with balanced outputs to compare this with, that is a Cambridge unit.
First let me describe my setup.
For the purposes of the latest listening tests I have been using a Denon 2910 for transport.
I will list input/output impedances in cases of very low output impedance I will simply say 0 though I know it is actually a bit more.
The chain looks like this:
OPUS (0) --> (2.5K to 10K) Joshua Tree(750R) --> (100K) Twisted X Driver Preamp with 6db gain (0) --> (1K) Twisted X Overture sans instrumentation amp (0) --> (6-8) Cryolite speakers.
The OPUS, JT, and Preamp are all in the same chassis, so everything is directly wired. Everything is fed and attenuates/amplifies the balanced signal.
First I have to say that the DAC(well the whole setup really) is incredibly quiet, there is no way to know audibly that it is "on" except to play some music. Ear to the tweeter, nothing....
The Opus has noticably better dynamics then the cambridge unit, though neither is a slouch by any means. I played the Penguin recording of "Rhapsody in Blue" and was very happy with the imaging and detail. Solid "you are there" bass slam. The muted trombones sounded like they were in the room.
One fear I had was that with no external filter the OPUS would sound harsh. I can say now that fear was misplaced, it is not harsh at all, but is very very faithful and detailed. You won't miss anything in the recording.
When you spend hours and hours designing something like this you really look hard for flaws, because this is a beta PCB and I know I can fix them still. But honestly, I can't find anything significant to change.
There is only one minor detail about the Beta PCBs which should be kept in mind. JP and other suggested we mute the DAC on receiver errors from the CS8416. Well that works great, but if you have a CD with some significant scratches or something on it the DAC will mute when the receiver detects the bad data. This can seem odd, but it only happens when the CD actually has a problem. You can avoid this muting by simply omiting U4, or cutting the trace to the mute pin. It turns out that the receiver does a pretty good job of handling errors on its own, and muting the DAC is actually not necessary.
The next PCB revision will include a jumper after U4 to make the mute option selectable so that we can still have the "lock" LED without the momentary muting the DAC when a short lived error occurs.
Anyway the bottom line is, I love the DAC, I am very excited and pleased, I cannot stop listening to it. My wife thinks I am nuts. I am nuts. I wish someone here could come by and listen to it with me.
Thanks again to JP, Craig, Terry, and the rest of you fellow nuts who really are responsible for pushing this project to success. My beer fridge will always be open to you. 🙂
One more thing, Brian Donegan is the man. He does not get enough credit for what he does with me. He is an awesome sounding board and always has great feedback, and has saved my butt many times. Thanks Brian!
Cheers!
Russ
Ok since it has been asked, I will give you my opinion on the sound. Keep in mind I am anything but objective on this subject. I would really rather hear how some third party feels about it. 🙂
I have one other DAC with balanced outputs to compare this with, that is a Cambridge unit.
First let me describe my setup.
For the purposes of the latest listening tests I have been using a Denon 2910 for transport.
I will list input/output impedances in cases of very low output impedance I will simply say 0 though I know it is actually a bit more.
The chain looks like this:
OPUS (0) --> (2.5K to 10K) Joshua Tree(750R) --> (100K) Twisted X Driver Preamp with 6db gain (0) --> (1K) Twisted X Overture sans instrumentation amp (0) --> (6-8) Cryolite speakers.
The OPUS, JT, and Preamp are all in the same chassis, so everything is directly wired. Everything is fed and attenuates/amplifies the balanced signal.
First I have to say that the DAC(well the whole setup really) is incredibly quiet, there is no way to know audibly that it is "on" except to play some music. Ear to the tweeter, nothing....
The Opus has noticably better dynamics then the cambridge unit, though neither is a slouch by any means. I played the Penguin recording of "Rhapsody in Blue" and was very happy with the imaging and detail. Solid "you are there" bass slam. The muted trombones sounded like they were in the room.
One fear I had was that with no external filter the OPUS would sound harsh. I can say now that fear was misplaced, it is not harsh at all, but is very very faithful and detailed. You won't miss anything in the recording.
When you spend hours and hours designing something like this you really look hard for flaws, because this is a beta PCB and I know I can fix them still. But honestly, I can't find anything significant to change.
There is only one minor detail about the Beta PCBs which should be kept in mind. JP and other suggested we mute the DAC on receiver errors from the CS8416. Well that works great, but if you have a CD with some significant scratches or something on it the DAC will mute when the receiver detects the bad data. This can seem odd, but it only happens when the CD actually has a problem. You can avoid this muting by simply omiting U4, or cutting the trace to the mute pin. It turns out that the receiver does a pretty good job of handling errors on its own, and muting the DAC is actually not necessary.
The next PCB revision will include a jumper after U4 to make the mute option selectable so that we can still have the "lock" LED without the momentary muting the DAC when a short lived error occurs.
Anyway the bottom line is, I love the DAC, I am very excited and pleased, I cannot stop listening to it. My wife thinks I am nuts. I am nuts. I wish someone here could come by and listen to it with me.
Thanks again to JP, Craig, Terry, and the rest of you fellow nuts who really are responsible for pushing this project to success. My beer fridge will always be open to you. 🙂
One more thing, Brian Donegan is the man. He does not get enough credit for what he does with me. He is an awesome sounding board and always has great feedback, and has saved my butt many times. Thanks Brian!
Cheers!
Russ
On test data.
I don't have the facilities to measure the DAC performance.
Occasionally my buddies at UT will do some testing for me, but I will not be able to do that any time soon.
I am open to the following idea. If someone who can do critical measurments wants to do it I can send them a functional DAC for testing/measuring purposes. If they want they can then either send it back or buy it at my cost.
If someone is interested in doing this please contact me by email.
I would love to know how the DAC actually does measure.
Cheers!
Russ
I don't have the facilities to measure the DAC performance.
Occasionally my buddies at UT will do some testing for me, but I will not be able to do that any time soon.
I am open to the following idea. If someone who can do critical measurments wants to do it I can send them a functional DAC for testing/measuring purposes. If they want they can then either send it back or buy it at my cost.
If someone is interested in doing this please contact me by email.
I would love to know how the DAC actually does measure.
Cheers!
Russ
sounds great!
the PCBS look great and good job you guys did with the whole thing.
I am very interested to try this DAC out.
the PCBS look great and good job you guys did with the whole thing.
I am very interested to try this DAC out.
Re: Subjective post, you can safely ignore... 🙂
Make that a red wine and I'll pop over sometime 😉 I am glad things worked out so well ( subjective or not ), I thought earlier this project is too well designed/thought over to be called a beta design really.
I especially liked the communication on the DAC per email, it is still amazing to see the collaboration Internet makes possible ( only the timedifference can be a drawback ). However some small bug is generally to be expected ( ground issues can pop up during measurements ). For now let's call the muting feature ( though pretty normal ) a bug to keep the criticisers happy...
Now where is that "beta" kit Russ ?
Russ White said:
Thanks again to JP, Craig, Terry, and the rest of you fellow nuts who really are responsible for pushing this project to success. My beer fridge will always be open to you. 🙂
Make that a red wine and I'll pop over sometime 😉 I am glad things worked out so well ( subjective or not ), I thought earlier this project is too well designed/thought over to be called a beta design really.
I especially liked the communication on the DAC per email, it is still amazing to see the collaboration Internet makes possible ( only the timedifference can be a drawback ). However some small bug is generally to be expected ( ground issues can pop up during measurements ). For now let's call the muting feature ( though pretty normal ) a bug to keep the criticisers happy...
Now where is that "beta" kit Russ ?
Re: Re: Subjective post, you can safely ignore... 🙂
Oh, I have plenty of red wine! You are always welcome.
Now for the beta kits, we only had a small number of DAC chips and Brian needs to get a few more. Brian is working up the final tabulation of costs. When he is done we will update the order page.
Once the beta PCBs are all gone we will order the final version.
I am fairly confident the cost of beta kits will be $99, that will just about cover our costs. That is for the DAC + PS PCBs + parts. Final version will be slightly more.
Cheers!
Russ
jean-paul said:
Oh, I have plenty of red wine! You are always welcome.
Now for the beta kits, we only had a small number of DAC chips and Brian needs to get a few more. Brian is working up the final tabulation of costs. When he is done we will update the order page.
Once the beta PCBs are all gone we will order the final version.
I am fairly confident the cost of beta kits will be $99, that will just about cover our costs. That is for the DAC + PS PCBs + parts. Final version will be slightly more.
Cheers!
Russ
Re: Re: Re: Subjective post, you can safely ignore... 🙂
I agree Jean-Paul. And I am constantly amazed at the number of really interesting, high-quality, projects being produced here on diyAudio in all areas.
I want to thank you for creating this project, Russ. I have been wanting to convert my high-end system to completely balanced, from source to amps for a years. Getting a TVC was the first step. I am now adding a balanced Aikido amp to that and working on an fully balanced phono preamp made up of 2 or 3 balanced Akido stages. At the end I have the fully differential DIY version of Audiotropics "Musical Machine" PP amp.
I agree Jean-Paul. And I am constantly amazed at the number of really interesting, high-quality, projects being produced here on diyAudio in all areas.
I want to thank you for creating this project, Russ. I have been wanting to convert my high-end system to completely balanced, from source to amps for a years. Getting a TVC was the first step. I am now adding a balanced Aikido amp to that and working on an fully balanced phono preamp made up of 2 or 3 balanced Akido stages. At the end I have the fully differential DIY version of Audiotropics "Musical Machine" PP amp.
Re: Re: Re: Subjective post, you can safely ignore... 🙂
That sounds very reasonable. I may want to compare your DAC to mine.
Russ White said:
That sounds very reasonable. I may want to compare your DAC to mine.
Russ,
This news makes me very excited indeed. Job well done!
I'll be starting a new thread in a couple of weeks for my balanced DAC design that I've been e-mailing you about, and it will be very interesteing to hear the differences as I've taken a very different design route. I'm just waiting for one of the IC's (which has somehow become very difficult to obtain) to arrive so I can start putting it together.
Cheers for now.
Terry
P.S. Etching your own pcb's for SSOP style IC's is a real pain in the putootie. I don't think I will try that again.
This news makes me very excited indeed. Job well done!
This is a sentiment you and I share, and as you did for me with the Twisted X-Bosoz, I will try my best to give you some objective feedback on the Opus. I can't wait to get my own Opus built and running.
I'll be starting a new thread in a couple of weeks for my balanced DAC design that I've been e-mailing you about, and it will be very interesteing to hear the differences as I've taken a very different design route. I'm just waiting for one of the IC's (which has somehow become very difficult to obtain) to arrive so I can start putting it together.
Cheers for now.
Terry
P.S. Etching your own pcb's for SSOP style IC's is a real pain in the putootie. I don't think I will try that again.
Attachments
Hi Terry,
Thank you very much!
I am very excited to see how your project progresses too. I really appreciate your support and all I have learned from your work.
I will follow the thread very intently.
I never knew what I was missing until I went fully balanced. I don't know if I can go back to single ended. 🙂
I concur, etching for tiny SMD stuff really stinks. Very easy for SOIC etc but MSOP and that sort of thing takes it out of me.
From now on I will probably just bite the bullet and get prototypes done at PCB Pool. PCB Pool does great work, but its not that cheap. One cool thing is that they take eagle files directly.
Cheers!
Russ
Thank you very much!
I am very excited to see how your project progresses too. I really appreciate your support and all I have learned from your work.
I will follow the thread very intently.
I never knew what I was missing until I went fully balanced. I don't know if I can go back to single ended. 🙂
I concur, etching for tiny SMD stuff really stinks. Very easy for SOIC etc but MSOP and that sort of thing takes it out of me.
From now on I will probably just bite the bullet and get prototypes done at PCB Pool. PCB Pool does great work, but its not that cheap. One cool thing is that they take eagle files directly.
Cheers!
Russ
>I never knew what I was missing until I went fully balanced. I don't >know if I can go back to single ended.
Is there a way to get single ended output from this DAC?
To use it for example in combination with Kooka and MyRevC.
Is there a way to get single ended output from this DAC?
To use it for example in combination with Kooka and MyRevC.
KOHTOPA said:
Sure, there are a few ways.
The easiest is just to take the non-inverting output and GND to the Kooka. I have tested this and it sounds excellent.
You can also get a transformer that will convert the balanced signal to single ended. Something like the Neutrik NTL-1 (google it).
You can also rig up a simple op amp circuit to convert the balanced signal to single ended.
I would just try the first option and see if you like it, if not try the second, it is simple, and has some filtering benefits too.
Cheers!
Russ
I have been running SE ouputs from the DAC (as Russ descibed) through a SE Joshua Tree to a RevC. Sounds great.
PJN
Brian/Russ,
If I understand correctly what you are saying it would be possible to have both single ended and balances output from the opus ?
I would like to give it a try using my Kook/RevC at first, but eventually would like to build one of your balanced amps. On the back of the dac case I could put both balanced and single ended outputs. That way I figure that I'd be set for the future. Could you provide some pictures of how to take the single ended output off of the board ?
PJN
Brian/Russ,
If I understand correctly what you are saying it would be possible to have both single ended and balances output from the opus ?
I would like to give it a try using my Kook/RevC at first, but eventually would like to build one of your balanced amps. On the back of the dac case I could put both balanced and single ended outputs. That way I figure that I'd be set for the future. Could you provide some pictures of how to take the single ended output off of the board ?
PJN
I'm really looking forward to building one of these.
Do you think the buffer could drive two amplifiers? I'd like to build one with two outputs for my mains and subwoofer.
Should I plan on using two buffers or would one be enough?
Do you think the buffer could drive two amplifiers? I'd like to build one with two outputs for my mains and subwoofer.
Should I plan on using two buffers or would one be enough?
Re: PJN
Its pretty easy to describe, but perhaps I can draw something up later.
Here is what I would do.
Because you can directly drive a load down to 1K with the Opus you have a lot of flexibility, and don't generally "need" a buffer at all.
I would simply wire an XLR for balanced output for each channel then run a wire from + out (non-inverting) from both to two RCA jacks. All GNDs would come together at the DAC.
You could then easily use either output, or even both if the input impedances of the targets are sufficiently high (say > 22K).
:EDIT: One exception to this case would be a situation where you had DC on the target input(which can happen). In that case you would probably be asking for trouble.
Cheers!
Russ
Nortp said:
Its pretty easy to describe, but perhaps I can draw something up later.
Here is what I would do.
Because you can directly drive a load down to 1K with the Opus you have a lot of flexibility, and don't generally "need" a buffer at all.
I would simply wire an XLR for balanced output for each channel then run a wire from + out (non-inverting) from both to two RCA jacks. All GNDs would come together at the DAC.
You could then easily use either output, or even both if the input impedances of the targets are sufficiently high (say > 22K).
:EDIT: One exception to this case would be a situation where you had DC on the target input(which can happen). In that case you would probably be asking for trouble.
Cheers!
Russ
preiter said:
If you have two loads look at them as a parallel load.
Here is the way I have been using mine.
OPUS --> ATTENUATOR(JT) --> BALANCED BUFFER --> MAIN POWER AMP(BAL) & SUBWOOFER AMP(SE)
Where the sub amp is driven by the same buffer, but only with the non-inverted signal.
The reason I use a buffer here is because the power amp has a low input impedance and the attenuator a 750 ohm output impedance. Because the buffer has a high (100K) input impedance it is a good load for the attenuator.
The buffer is what we call "TXD" which has its own thread here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=87631&perpage=10&pagenumber=1
TXD is also the driver portion of the main power amp.
Cheers!
Russ