Hi Jens,
Keep us posted and once you have the price lets us know. Very interesting piece of professional audio gear.
Keep us posted and once you have the price lets us know. Very interesting piece of professional audio gear.
Hi Jens, great project. I'm using the same ADC & DAC with a project of my own, was just wondering a few things:
- do you bias the ADC input buffer from the ADC VREF, or just from a standard resistor divider as in the datasheet/EVM?
- do you sum the DAC differential outputs to SE and then make them differential again later (as some designers prefer due to improved CMRR) or just go differential all the way from DAC to output?
- Any experience with DC-coupled OPA1632D straight at the DAC output? Initial test results on a preceding AK4396 in a space-conscious design showed no big difference when simply DC-coupling the DAC output to a OPA1632D buffer than via 100uF caps.
- do you bias the ADC input buffer from the ADC VREF, or just from a standard resistor divider as in the datasheet/EVM?
- do you sum the DAC differential outputs to SE and then make them differential again later (as some designers prefer due to improved CMRR) or just go differential all the way from DAC to output?
- Any experience with DC-coupled OPA1632D straight at the DAC output? Initial test results on a preceding AK4396 in a space-conscious design showed no big difference when simply DC-coupling the DAC output to a OPA1632D buffer than via 100uF caps.
I have seen a big difference in THD with DC and AC coupling of 1632, working with PCM1804 and AK4394.
I tend to agree with Demian 🙂
Some time ago I got access to a relatively well-known Audio Tester. I have attached a comparison of the generator in that one and the generator in my own Audio Analyzer.
The noise floor of my generator is relatively high. This is because the DAC is used at -20dBFS in this case, loosing some of the dynamic range. But improving the distortion a lot as well.
@PWatts
Yes, the bias circuit is a resistor divider with decoupling.
I use differential design all the way through. DC-coupled by the way.
I have not tried the OPA1632 together with the AK4490. I used it in one of the first test boards together with AK4399 and AK5394A. On the DAC side I used LME49710 directly on the DAC outputs and the OPA1632 was used as the output driver. It seemed to be too sensitive to the load on the output, so I changed it to a different design.
Some time ago I got access to a relatively well-known Audio Tester. I have attached a comparison of the generator in that one and the generator in my own Audio Analyzer.
The noise floor of my generator is relatively high. This is because the DAC is used at -20dBFS in this case, loosing some of the dynamic range. But improving the distortion a lot as well.
@PWatts
Yes, the bias circuit is a resistor divider with decoupling.
I use differential design all the way through. DC-coupled by the way.
I have not tried the OPA1632 together with the AK4490. I used it in one of the first test boards together with AK4399 and AK5394A. On the DAC side I used LME49710 directly on the DAC outputs and the OPA1632 was used as the output driver. It seemed to be too sensitive to the load on the output, so I changed it to a different design.
AK4497 has appeared at Digikey finally... but for $52! That's ESS level pricing 🙂. I suppose it's close in performance, but the AK4490 was so cheap in comparison.
What is an extra dB worth to you? ESS demonstrated that you can get that price so why not? Getting it on a board that will extract the performance is a bigger challenge.
Very true. I still prefer it because the part is available through Digikey and the datasheet doesn't require an NDA. What a stupid practice.
Not to derail, but do you have contact info for an applications guy there? I was wondering if the "heavy load" drive mode had any downsides, but the datasheet is really short on information.
Not to derail, but do you have contact info for an applications guy there? I was wondering if the "heavy load" drive mode had any downsides, but the datasheet is really short on information.
I'd love to see the final result!
Are you planning on selling them? (I'm sorry if this was mentioned somewhere in the middle of the thread, I haven't read all of it, yet ).
If so, is there any indication of price?
Are you planning on selling them? (I'm sorry if this was mentioned somewhere in the middle of the thread, I haven't read all of it, yet ).
If so, is there any indication of price?
It is the plan to make it available as a commercial product. Not directly from me, but from a company that I am involved with.
We still need to calculate the final production cost before we can announce a price.
We still need to calculate the final production cost before we can announce a price.
taking way to long to launch this product!
stop fooling about, get the product done already!
at least get some prototypes out there so you can fix/debug it get feedback etc.
now with all that said I would gladly be a beta tester for you 🙂
stop fooling about, get the product done already!
at least get some prototypes out there so you can fix/debug it get feedback etc.
now with all that said I would gladly be a beta tester for you 🙂
JensH,
Hope it will be a well rewarding commercial product.
Also hope, the price range makes a good analyzer available to DIY folks.