[Reactcore]

The metal that connects them is quite long, which makes for good aerials. That's my understanding.

The 2.5mm conductor on the left side is the PSU gnd.. this has the same potential as Davs's housing. (It is even mounted under a bolt) And no.. this cant pick up RF outside Dave

 

[Jawed]

The 2.5mm conductor on the left side is the PSU gnd.. this has the same potential as Davs's housing. (It is even mounted under a bolt) And no.. this cant pick up RF outside Dave

A connection to 0V and/or earth doesn't prevent RF currents being induced into the wires on components. Surface mount components are favoured when building circuits because the wire (lead, pin) is extremely short, giving a good defence against unwanted induced RF.

Also there's RF noise being generated within DAVE so it's a question of how strong the airborne effect is and how that interacts with your added capacitors.

Unfortunately there's quite a lot of combinations of the various capacitor modifications you've made (including without the orange capacitors) which all need to be evaluated very carefully, in theory. Tedious work...

 

[Reactcore]

A connection to 0V and/or earth doesn't prevent RF currents being induced into the wires on components. Surface mount components are favoured when building circuits because the wire (lead, pin) is extremely short, giving a good defence against unwanted induced RF.

Also there's RF noise being generated within DAVE so it's a question of how strong the airborne effect is and how that interacts with your added capacitors.

Unfortunately there's quite a lot of combinations of the various capacitor modifications you've made (including without the orange capacitors) which all need to be evaluated very carefully, in theory. Tedious work...

Its not Dave's own generated RF im worried about.. only random from outside.

My ears tell me the sound benefits of the caps prevail over any negative effect of them being in there.. i did extensive A-B comparing next to a stock Dave and im not going back

 

[Reactcore]

So i now did a different approach.
This sounds really promising!

I exchanged the 2 parallel 470uf caps (50mohm esr) for a single 1000uf (17mohm) direct on the pos. and neg. regulator outputs.
My theory is that 2 parallel caps still differ in capacity (dis)charging each other with audio related currents.. this can give a tiny ripple which is amplified by Dave's amp feedback.
This can interfere with certain frequencies.

I get more body to instruments again and meatier mids but not trading transparency like i had before.. the rumbling sub low end also remains.

I have alot listening ahead..

I layed them flat with thick wires to the regulators.

 

[Reactcore]

Omg.. i felt so small listening to Howard Shore's mighty orchestra.. never had so much tears before... this sounds so damn real ..endgame stuff..

Now im on the right path.. i will try other caps still.. but definately keep on single setup

 

[Jawed]

My theory is that 2 parallel caps still differ in capacity (dis)charging each other with audio related currents..

The orange capacitors are in parallel, will they also be (dis)charging each other? Do you think that will affect sound quality?

 

[Reactcore]

The orange capacitors are in parallel, will they also be (dis)charging each other? Do you think that will affect sound quality?

I was thinking of the same possibillity..

Therefore im now testing per voltage rails one orange cap on input and one on output.. having less total capacity but lower ESR on the output (amp) side compared to the Nichicon..

I notice a bit less ultra sub bass but still very impactful ..the treble is maybe a tad more airy but this might just be the result of the bass change. Its clear that the amp side of the regulator is most sensitive to the negative parallel effect..

 

[Jawed]

I also wonder whether DAVE's existing capacitors on the main board, which are close to the Molex from the SMPS are also effectively in parallel with the orange capacitors that you originally added. So that the "parallel capacitors problem" was created as soon as you added the orange capacitors, and remains even if you have a single orange capacitor on the "input" for the voltage regulator.

Now to be frank I'm no electronics guy, so I'm mostly posting questions and ideas.

One thing I wonder is whether the capacitor values are, themselves tuned for the application. 470 or 1000 or 1700uF are all going to have quite direct effects on the operation of the circuit after the regulator, in addition to ESR.

I wonder whether the configuration seen with DAVE is a "compromise" of headphone versus line-level drive. As you change the circuit to make it better for headphones it becomes "worse" for feeding into a power amp (line level).

I suppose there are lessons in the output circuit of TT2, but you can't directly transfer them to DAVE.

 

[Reactcore]

I also wonder whether DAVE's existing capacitors on the main board, which are close to the Molex from the SMPS are also effectively in parallel with the orange capacitors that you originally added. So that the "parallel capacitors problem" was created as soon as you added the orange capacitors, and remains even if you have a single orange capacitor on the "input" for the voltage regulator.

Now to be frank I'm no electronics guy, so I'm mostly posting questions and ideas.

One thing I wonder is whether the capacitor values are, themselves tuned for the application. 470 or 1000 or 1700uF are all going to have quite direct effects on the operation of the circuit after the regulator, in addition to ESR.

I wonder whether the configuration seen with DAVE is a "compromise" of headphone versus line-level drive. As you change the circuit to make it better for headphones it becomes "worse" for feeding into a power amp (line level).

I suppose there are lessons in the output circuit of TT2, but you can't directly transfer them to DAVE.

Good thinking.

Its true there still exist a parallel setup.. actually the smps has even a 3rd set of caps parallel to Dave's 3 input ones.

But i did extensive comparing my orange capped Dave with a stock Dave and to TT2 and stock sounds 'thin' next to modified and TT2.

Its also what many reviewers of TT2 say about its amp drive being superior.

Line out does not seem to suffer or degrade as any improvement in bass and body to the sound is also hearable through my HP amp and speakers/amp. Allbeit to a smaller extent.

 

[Reactcore]

So far im still stunned by the sound the last single cap setup made. So much authority and control on my headphones.

But im not stopping yet, so im about to try a different brand and type of caps.

This time i exchange the two 1000uF 17mohm ESR Nichicons for 2200uF Chemicon type.
These are a newly released 8mohm version.

Lets have a listen..

 

[miketlse]

Keep experimenting. Your posts are starting to sound like some of the posts on the Lord Gwyn thread about valve amplifier design. By this I mean that certain brands or types of component (usually more expensive) are described as sounding better. This is not a criticism but recent posts on the lord Gwyn thread reckon that metal film resistors sound better than carbon film - maybe this is true, so it is interesting to hear the results of your experiments.

 

[TheAttorney]

But im not stopping yet, so im about to try a different brand and type of caps.

This time i exchange the two 1000uF 17mohm ESR Nichicons for 2200uF Chemicon type.
These are a newly released 8mohm version.

If you find that the new ones do indeed sound different (for better or worse) then I suggest the next step, for the benefit of this community , is you try the Audio Note caps - to see if the posh "audiophile" versions can beat the higher specified "normal" versions. Seeing as the Audio Notes subjectively beat all rivals in the Sean Jacobs DC4-related caps mod.

 

[Reactcore]

If you find that the new ones do indeed sound different (for better or worse) then I suggest the next step, for the benefit of this community , is you try the Audio Note caps - to see if the posh "audiophile" versions can beat the higher specified "normal" versions. Seeing as the Audio Notes subjectively beat all rivals in the Sean Jacobs DC4-related caps mod.

I have looked those up.. but sadly i couldnt find their specs of physical size and ESR value. By looking at the pictures they seem too big to fit in the space between the volume rotary pcb and mainboard..

As for my last change, i had only yesterday evening a listen and just fired it up now as i write this..

My first impression was hm.. it sounds warmer, softer in highs and utmost full bodied.. but then i noticed the trebble is better controlled in a good way.. i can hear texture in the upper register that was harder to make out before.

Say for example where i first still could hear sometimes and on some edgier recorded tracks sissling in human voices.. this became easier to listen to. This flows into upper midrange complementing the (mid)bass area balancing the total presentation further out comparing to the previous caps.

I had some spooky mind trickling moments of hearing someone in my room which was actually in the studio background with body on their voices even if theyre 'far' away from the mike which is next to the musicians playing.

On a Gerry Mulligan jazz track the saxophone had a unDavely warm and full sound like a TT2 but then a crispy clear hihat sound sets in.. cold and with real metal texture.. this mixture of warm and cold textured intruments sounds utterly reallife with glass clear room reflections.

Its unbelievable what these cap treatments do to Dave's amp stage. And im just using the stock SMPS which for me is nicely and naturally filtering RF from the mains as Rob explained. I did took the earth wire off though.

I have ordered parts to place the SMPS in a separate box to see if this gives benefit since it might has some radiated emc to keep out Dave's casing.. i post more on that later

 

[Reactcore]

Another explaining post about the importance of low ESR here:

https://www.head-fi.org/threads/chord-electronics-dave.766517/post-17488049

 

[Reactcore]

Being already quite happy with the sound i made a next change on my Dave.

This time i took the original PSU out to place it in an external box. Its to keep any possible radiated RFI out of Dave's casing. Also it keeps Dave cooler since the PSU generates its own heat. And lastly prepare Dave for a later addon.. to create a non switching cleanest possible battery supply.

The eye wants someting too so first i designed an aluminium plate to slide into the place where normally the C19 socket and switch sits. Its made using CNC by the same fabric that made my Choral scaler housing, brushed black anodized.

A flat sided hole in it to mount a high quality Lemo FGG2B type connector chassis.

Ive got shielded 4x 1,5mm pure copper cable to solder on the pins, the shield connected with the PSU ground (green wire)

To reduce the number of contacts in the power feed i soldered the other end of the one meter cable directly on the PSU taking the molex header out. Same i did for the mains side and ditched the switch.

The original RF filter is replaced by one with soldered wires instead of a C19 socket, again to lose plug contacts.

Mounted into a box with ventilation holes it looks like this The PSU is placed rotated to fit the filter.

Also in Dave the molex connector made place for direct soldered wiring.

Closing the lids gave me the result of my external original PSU powered Dave.

Its time for critical listening.. first impressions are already promising.. buttery smooth and extended treble.. more to describe later..

Thanks again for reading