CHORD ELECTRONICS DAVE
Jul 17, 2022 at 3:50 PM Post #21,451 of 25,914
By the way are you doing the same with the digital circuit in Dave? For my money that is at least as dependant as the analogue stages and reacts very clearly to all sorts of aspects of the power supply.
Not with the supercaps.. this aims on Dave's amp only.

Later i will build my battery supply for 5v and +/-15v. I have my design ready.
This will take it away from the net RF and take switching out.
 
Jul 17, 2022 at 4:44 PM Post #21,452 of 25,914
Not with the supercaps.. this aims on Dave's amp only.

Later i will build my battery supply for 5v and +/-15v. I have my design ready.
This will take it away from the net RF and take switching out.
It will be interesting even if I suspect your faith is supercaps is misplaced. Are you going in this direction because of wanting to use headphones? I never use headphones so perhaps that accounts for my different point of view?

Did you see this battery project to power Dave?
https://audiophilestyle.com/forums/...dio-streaming/?do=findComment&comment=1149407
 
Jul 17, 2022 at 5:32 PM Post #21,453 of 25,914
It will be interesting even if I suspect your faith is supercaps is misplaced. Are you going in this direction because of wanting to use headphones? I never use headphones so perhaps that accounts for my different point of view?

Did you see this battery project to power Dave?
https://audiophilestyle.com/forums/...dio-streaming/?do=findComment&comment=1149407
Nice read. It confirms my take on the importance of having low ESR.

But ..as low the impedance of a outboard PSU might be.. itll need to pass through a cable, Daves molex, PCB tracks and ultimately the LM regulator.. significantly adding to this resistance..

Thats why i go to the end of the chain and apply them directly over the OP transistors

People say Dave's amp lacks 'dynamic power' compared to the best external ones.. but is best for transparency.. so i try to improve it by feeding it more stable voltage

The digital part im not touching as of yet
 
Jul 17, 2022 at 10:43 PM Post #21,455 of 25,914
DAVE now on Model 2 Vibrapod's .... Wow! Wasn't expecting that 😳 Bass has tightened up and become more full in delivery. All because of these 'Pods... 'Well I never!'
Crazy, huh? That’s how I felt. The cones take it even a little bit further.
 
Jul 18, 2022 at 1:31 AM Post #21,456 of 25,914
Nice read. It confirms my take on the importance of having low ESR.

But ..as low the impedance of a outboard PSU might be.. itll need to pass through a cable, Daves molex, PCB tracks and ultimately the LM regulator.. significantly adding to this resistance..

Thats why i go to the end of the chain and apply them directly over the OP transistors

People say Dave's amp lacks 'dynamic power' compared to the best external ones.. but is best for transparency.. so i try to improve it by feeding it more stable voltage

The digital part im not touching as of yet
With my various cap experiments the lowest ESR were the worst sounding of all the different manufacturer offerings that I tried. Initially they were of the ‘oh, wow’ category (life like detail, realism, best soundstage, more slam etc) but more rigorous listening revealed detail masking noise induced artefacts. My listening companion was trying to convince me the very low ESR caps were the best Dave sound he had heard but he soon relented when I demonstrated others without all those fatigue inducing aspects.

It would be good if you could compare various makes of supercaps to see if you get the variations in sound that I expect.
 
Jul 18, 2022 at 2:15 AM Post #21,457 of 25,914
It would be good if you could compare various makes of supercaps to see if you get the variations in sound that I expect.
I assume you tried them on the molex power input?

Sadly i dont have many on hand. When i worked as a repair engineer i had access to a storehouse full of components.. not to mention professional measurement equipment. Now im waiting on China shipments

Lets first see how they compare to those 85° 470uF stock ones (which will stay there but with the 5F ones parallel over them)
 
Last edited:
Jul 18, 2022 at 2:39 AM Post #21,458 of 25,914
When the going gets tough, the first actual "pull" in a device is from the dc power rails within the device.

The device's psu sits between these rails and the mains.

If the psu cannot deal with the pull without the voltages on the power rails sagging then that's when the problems start. The ability of the mains to deliver power becomes irrelevant as the psu is now a bottleneck.

Providing the psu with extra capacitance enables it to hold the rail voltages up when the internals of the device suddenly demand more power.

Capacitors in a psu therefore can have one of at least two functions: as part of a passive LC filter to suppress ripple, or as an energy reserve to support short-term power demands.

Capacitors are expensive components. When requirements such as quality, increasing capacitance value and voltage range, and higher temperature resistance are specified the cost of each rockets.

When the psu "haircut" to reduce device cost is applied then capacitors are an obvious target for savings.

This is one reason why replacing the stock psu with a highly-specified psu very often results in startling sq jumps.

Your explanation is just plain wrong. Do you think I do not know what I am doing? The PSU interaction with signal related currents is complicated and is a significant source of distortion and SQ issues - all of which has been designed for and accommodated with Dave. Dave would not show the extraordinary low levels of distortion if I had not completely eliminated this issue.

Dave PSU interactions is complex, but is dominated by the very low impedance linear regulator, and the amp PSU rejection ratio. If you were to use a DCA Stealth at -3dB (way too loud) the HP would be drawing 130 mA. It's easy to calculate the PSU induced error from the amp and linear regulator and that comes out at -198dB. That is negligible compared to the distortion of the output stage, which is a thousand times greater than this, and considering this error would induce simple harmonic distortion only, you could consider it as inaudible so not a problem.

But this error at -198dB is just from the linear regulator, and is nothing to do with the supplied SMPS. What is the error from that? Worst case it comes out at -234dB, or 66 times smaller a problem. So your argument relies on hearing an error that is 66,000 times smaller than the distortion in the output stage?

Like I keep saying - it's the RF noise characteristics that changes the SQ with PSUs. And in my experience, SMPS offers lower random RF noise than a linear PSU, as they do not have RF filters built in.
 
Jul 18, 2022 at 2:56 AM Post #21,459 of 25,914
Has Rob heard Dave with any aftermarket power supply’s? What were his thoughts if he has ?
Rob believes SMPS is the best tech for Chord dacs. I agree with him that if well implemented SMPS has higher performance and lower noise than LPS. All my dacs use SMPS. Could Dave be improved with a purpose built SMPS and not using an off the shelf part intended for medical instruments? Possibly.
 
Last edited:
Jul 18, 2022 at 2:59 AM Post #21,460 of 25,914
Like I keep saying - it's the RF noise characteristics that changes the SQ with PSUs. And in my experience, SMPS offers lower random RF noise than a linear PSU, as they do not have RF filters built in.
Tested this with Dave and M-scaler and completely agree. Though I might have had other issues with the M-scaler, it sounded better with the stock psu than the Farad, and better still run off a battery. Despite popular opinions.
 
Jul 18, 2022 at 3:25 AM Post #21,461 of 25,914
As someone who uses a mains filter + a power regenerator plugged into it and has seen massive performance gains from them, both in separation, and cumulatively
Just on this, I have singularly failed to be impressed by any power regenerators I have tried, including some costing near the thick end of 10k. All seemed to give a slight hardness to the top end and all injected electrical noise back into the mains wall sockets. On the other hand what they did do very well is to tame my high mains voltage (250V) which was making my 845 valve amps run a bit too near their limits for my liking. When I got my ss amps the regenerators were sold and replaced by a 3KVA balanced mains transformer to run all my system from it with no need for any additional filters.
 
Jul 18, 2022 at 3:37 AM Post #21,462 of 25,914
Dave PSU interactions is complex, but is dominated by the very low impedance linear regulator, and the amp PSU rejection ratio. If you were to use a DCA Stealth at -3dB (way too loud) the HP would be drawing 130 mA. It's easy to calculate the PSU induced error from the amp and linear regulator and that comes out at -198dB. That is negligible compared to the distortion of the output stage, which is a thousand times greater than this, and considering this error would induce simple harmonic distortion only, you could consider it as inaudible so not a problem.

Like I keep saying - it's the RF noise characteristics that changes the SQ with PSUs. And in my experience, SMPS offers lower random RF noise than a linear PSU, as they do not have RF filters built in.
I concur on this. Love the sound of the Stealth on stock Dave. I've had many issue with LPS that is aligned with what Rob Watts is saying.

-3dB is Susvara level listening and while Stealth is 3 to 4 clicks lower.
 
Last edited:
Jul 18, 2022 at 3:38 AM Post #21,463 of 25,914
Tested this with Dave and M-scaler and completely agree. Though I might have had other issues with the M-scaler, it sounded better with the stock psu than the Farad, and better still run off a battery. Despite popular opinions.
Lately I've tried powerbank with m scaler against farad3 (again), and I think that I liked sound more.
I need further testing but who knows, I could end using car battery for m scaler :wink:
 
Jul 18, 2022 at 3:41 AM Post #21,464 of 25,914
Lately I've tried powerbank with m scaler against farad3 (again), and I think that I liked sound more.
I need further testing but who knows, I could end using car battery for m scaler :wink:
Yes that shows the lack of noise rejection on the psu.

Rob believes SMPS is the best tech for Chord dacs. I agree with him that if well implemented SMPS has higher performance and lower noise than LPS. All my dacs use SMPS. Could Dave be improved with a purpose built SMPS and not using an off the shelf part intended for medical instruments? Possibly.
This is exactly why the Ifi Elite can beat the Hypsos and Farad easily. It's a high grade SMPS.
 
Jul 18, 2022 at 4:42 AM Post #21,465 of 25,914
For RF rejection i also believe a SMPS is better equipped by nature cause it has to filter its own generated switching noise to begin with.

Also yes im aware the current draw of a HP is tiny as <150mA.. but in my opinion it cant be wrong to make the rails voltage even more resistant to varying currents no matter how small.

But its a experiment.. i might have to conclude its not audible.

In TT2 its not for nothing this is done too..
And i dont think its done specially to drive 8ohm speaker loads
 
Last edited:

Users who are viewing this thread

Back
Top