Hey guys
The Hermes-RPI works by supplying a divided bit clock where the rate is selected by the driver via GPIO. So the Rpi works with the slave in regard to the bitclock. So basically the Hermes gets an isolated master clock from the cronus and divides it based on the output sample rate to get the bit clock. The bit clock, data, and word clock (word clock and data coming from rpi) is fed back to the cronus (isolated) where is is finally reclocked so that it aligns with the master clock - removing any phase noise.
The only way to support DSD would be via DoP which fortunately is natively supported by the ES9028/38 so if you have a B3SE pro that is a very viable option.
Another feature is isolated I2C - so you can create a full featured source from the RPI - controlling all aspects of a DAC like the Buffalo III-SE-Pro.
The Hermes-RPI works by supplying a divided bit clock where the rate is selected by the driver via GPIO. So the Rpi works with the slave in regard to the bitclock. So basically the Hermes gets an isolated master clock from the cronus and divides it based on the output sample rate to get the bit clock. The bit clock, data, and word clock (word clock and data coming from rpi) is fed back to the cronus (isolated) where is is finally reclocked so that it aligns with the master clock - removing any phase noise.
The only way to support DSD would be via DoP which fortunately is natively supported by the ES9028/38 so if you have a B3SE pro that is a very viable option.
Another feature is isolated I2C - so you can create a full featured source from the RPI - controlling all aspects of a DAC like the Buffalo III-SE-Pro.
Hello,
Im in the process of building a multi dac platform with basically 4 AK4490 pcb. now comes the question of the clock distribution and receiver while minimizing noise and jitter.
seems the cronus with 2 cristals is appropriate whit its 4 outputs.
is it fine to use it in combinaison with a LVDS clock reveiver on each DAC board (like an SN65LVDS2 chip as an example?
is there some schematic or integration manual available ? cant find it yet
many thanks
Im in the process of building a multi dac platform with basically 4 AK4490 pcb. now comes the question of the clock distribution and receiver while minimizing noise and jitter.
seems the cronus with 2 cristals is appropriate whit its 4 outputs.
is it fine to use it in combinaison with a LVDS clock reveiver on each DAC board (like an SN65LVDS2 chip as an example?
is there some schematic or integration manual available ? cant find it yet
many thanks
Can someone please tell me what IC6 of the Cronus is? It's a 6 pin soic with AGN stamped on it. My Cronus hasn't worked from day one. The regulator ADM7154 is dead, so, I have injected a 3.3v power supply in it's place. Both oscillators are working, both frequencies are fed into this IC, but there's no output from IC6. I've been trying to get this running for two weeks now...
Hi Russ, Thanks for sending the replacement Cronus. Now, voltages look good, but I can't seem to get a lock.
Tried re-flashing Amanero + config settings, async etc according to the Amanero thread fist page: Introducing the Hermes-Amanero
Double-checked all the connections. Tried U.FL, soldered wires directly to Cronus.
Looked over all the joints. Decided to go with the thru-hole for R1-7 and they test good. Inspected the potato chip and the joints there look good. I'll try re-flowing these.
It's my understanding that the Amanero should not play if it is in slave mode and does not see the clock from Cronus? It just plays all the time for me, even if completely disconnected from Cronus. Is something amiss here?
I set up a test rig, and swap in/out with a OPUS, which works and I get lock / sound.
I suppose I should try flashing to Master mode and connect from Amanero directly to make sure that part works and then look further down the line?
I'll need a scope to test outputs from the Cronus correct?
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I am hoping to use a Cronus/Hermes/Amanero combo with a Soekris DAM1021. This was only briefly mentioned in earlier posts in this thread.
I have a question - the i2s connection to the DAM1021 requires a 3.3V and ground connection from the USB/i2s receiver. Where should I derive this 3.3V from the Cronus?
Thanks!
I have a question - the i2s connection to the DAM1021 requires a 3.3V and ground connection from the USB/i2s receiver. Where should I derive this 3.3V from the Cronus?
Thanks!
Hi Russ,
Currently using Roon -> RPi -> HiFi Berry Digi+ Pro -> I2S -> Buff II -> Legato.
Keen on Hermes-RPi and Cronos in lieu of the Digi+.
Is this available (or if not when) as I see discussion on this thread but it's not for sale on your website?
Also info and pics would be great!
Best regards,
Bruce
Currently using Roon -> RPi -> HiFi Berry Digi+ Pro -> I2S -> Buff II -> Legato.
Keen on Hermes-RPi and Cronos in lieu of the Digi+.
Is this available (or if not when) as I see discussion on this thread but it's not for sale on your website?
Also info and pics would be great!
Best regards,
Bruce
Hi guys.
I'm sorry being so late on software delivery...
The driver is fine most of the time but I encounter intermittent white noise from time to time.
Playing a new track with different samplerate fix it, but I need to find a suitable solution in the driver itself.
And real life is eating quite a lot of my spare time (job change and all...)
I need to lock 1 or 2 days to fix the driver and submit it to official kernel maintainers.
Cheers Grael
I'm sorry being so late on software delivery...
The driver is fine most of the time but I encounter intermittent white noise from time to time.
Playing a new track with different samplerate fix it, but I need to find a suitable solution in the driver itself.
And real life is eating quite a lot of my spare time (job change and all...)
I need to lock 1 or 2 days to fix the driver and submit it to official kernel maintainers.
Cheers Grael
Hey Grael - totally understand! Nice work so far - please reach out to Miero - he has skill on the driver side (having done the Hermes-BBB botic driver) - I bet between the two of you we can get this thing finished. I can't remeber if there is a github repo - if there is perhaps post that and anyone who likes could contribute.
We also sent Miero a prototype so he can help test.
I can't remeber if there is a github repo - if there is perhaps post that and anyone who likes could contribute.We also sent Miero a prototype so he can help test.
Grael, thanks for the code.
I've just briefly checked a patch and I propose to replace "TPA" in strings and comments with a full name "Twisted Pear Audio".
Another thing is a computation of a clock divider. The Cronus can be populated with clocks of different frequencies (e.g. 22.5/45 MHz). I guess we might want to have this configurable in the dts.
I might try to make a patch for this if you want (e.g. reuse some code from Botic driver)
I've just briefly checked a patch and I propose to replace "TPA" in strings and comments with a full name "Twisted Pear Audio".
Another thing is a computation of a clock divider. The Cronus can be populated with clocks of different frequencies (e.g. 22.5/45 MHz). I guess we might want to have this configurable in the dts.
I might try to make a patch for this if you want (e.g. reuse some code from Botic driver)
Hi Miero,
yes, in comments and in overlay README, "Twisted Pear Audio" should be used instead of TPA.
If the user have 22/24 clocks, he needs to bypass the Cronus on-board divider and to limit the samplerates to 192 kHz. (option max192 in the overlay)
If the user have higher clocks, he will use the Cronus on-board divider. (/2 for 45/49 clocks and /4 for 90/98 clocks).
An option to use 45/49 input clocks could be interesting to evaluate the feasibility of playing 705,6/768 kHz samplerates (/2 on the cronus with 90/98 clocks)
Maybe we could discuss all this in private first
Thanks!
yes, in comments and in overlay README, "Twisted Pear Audio" should be used instead of TPA.
I wrote the driver with 22/24 input clocks in mind.
If the user have 22/24 clocks, he needs to bypass the Cronus on-board divider and to limit the samplerates to 192 kHz. (option max192 in the overlay)
If the user have higher clocks, he will use the Cronus on-board divider. (/2 for 45/49 clocks and /4 for 90/98 clocks).
An option to use 45/49 input clocks could be interesting to evaluate the feasibility of playing 705,6/768 kHz samplerates (/2 on the cronus with 90/98 clocks)
Maybe we could discuss all this in private first
Thanks!
A little update on Hermes-RPi driver.
I think I've found a way to fix the "occasionnal white noise" problem.
I let it cook on my rig a few more days then if the problem doesn't come back, I'll push the fix on github.
I've also added two more options:
- clock45_49 to allow the Hermes to be fed by 45/49 MHz input clocks
(so 1:1 on Cronus with 45/49 clocks, or 1:2 on Cronus with 90/98 clocks)
- 32bit to allow full 32 bit samples (truncated to 24bit by default)
Integration to official kernel is coming closer.
I think I've found a way to fix the "occasionnal white noise" problem.
I let it cook on my rig a few more days then if the problem doesn't come back, I'll push the fix on github.
I've also added two more options:
- clock45_49 to allow the Hermes to be fed by 45/49 MHz input clocks
(so 1:1 on Cronus with 45/49 clocks, or 1:2 on Cronus with 90/98 clocks)
- 32bit to allow full 32 bit samples (truncated to 24bit by default)
Integration to official kernel is coming closer.
Or not...
I'm starting to think this has nothing to do with the driver or hermes/cronus...
Hi guys, hope this is the right place to post this.
I have a Cronus (with BBB Hermes) which has been working fine and helping things to sound wonderful for around a year now, but I've just moved stuff around in my case and something weird is happening.
It started with the musical output from my dac sounding all jangly, glitchy and horrible, so I investigated and I believe the Cronus is the issue one way or another.
The Cronus appears to be pulling a LOT of power and is making a mechanical noise... It's hard to describe, but it's a ticking that's fast enough to sound like a purrr.
I've isolated the Cronus from the DAC and the Hermes, so the only thing attached is the 5v power input and it's still doing it. The 5v power input is reduced to around 4v so it's pulling quite a load. This is with the same choke power supply and 5v regulator I've always used with it.
If I power the Cronus up with the Rhea clocks removed, the noise is gone and the input voltage reverts back to 5v. If I install only 1 of the clocks at a time in either position, it appears to be fine, but with both clocks installed, the noise/load is there.
Could someone help me troubleshoot my issue please? As far as I'm concerned, the only thing I've changed are the standoffs, but it means I've unplugged and reconnected everything in my case. I've pretty thoroughly checked my wiring and can't see an issue.
Is it normal for clocks like these to ever make an audible noise?
thanks,
James
I have a Cronus (with BBB Hermes) which has been working fine and helping things to sound wonderful for around a year now, but I've just moved stuff around in my case and something weird is happening.
It started with the musical output from my dac sounding all jangly, glitchy and horrible, so I investigated and I believe the Cronus is the issue one way or another.
The Cronus appears to be pulling a LOT of power and is making a mechanical noise... It's hard to describe, but it's a ticking that's fast enough to sound like a purrr.
I've isolated the Cronus from the DAC and the Hermes, so the only thing attached is the 5v power input and it's still doing it. The 5v power input is reduced to around 4v so it's pulling quite a load. This is with the same choke power supply and 5v regulator I've always used with it.
If I power the Cronus up with the Rhea clocks removed, the noise is gone and the input voltage reverts back to 5v. If I install only 1 of the clocks at a time in either position, it appears to be fine, but with both clocks installed, the noise/load is there.
Could someone help me troubleshoot my issue please? As far as I'm concerned, the only thing I've changed are the standoffs, but it means I've unplugged and reconnected everything in my case. I've pretty thoroughly checked my wiring and can't see an issue.
Is it normal for clocks like these to ever make an audible noise?
thanks,
James