(01-29-2024, 03:03 AM)varunach Wrote:

(01-29-2024, 01:44 AM)wolf7250 Wrote:

(01-28-2024, 07:52 PM)hifinet Wrote: You only need the one stacking header between the Q7 and ProtoDAC to prevent 5V from ProtoDAC feeding back to the 3.3V of the Q7 GPIO. Q7 isolates the topside isolated GPIO (J7) from the RPi. That is one of the things it does.

The noise is primarily conducted noise that the RPi is imparting on all of the GPIO lines, power, grounds and I2S, the entire GPIO. Q7 isolates J7 from all this. EMI is much less, orders of magnitude less, IMO.

Yes, I am saying that if you are going to circumvent the isolation of Q7, you might as well save yourself some money and go with MA. MA also has two jumpers so that you don't need to use the stacking header. See the previous posts of @michaelagiles . The solution in that case is to use an RPi that emits less noise. The RPi Zero W would have the least of the current RPi in that regard, since it is single core. In my experience, Zero W is less noisy than RPi 2, which is less noisy than RPi 3.

@hifinet I recently ordered one of your kits on EBAY and was intending to use it with the FiFoPi MA and a Raspberry Pi 3B+. Would you have any advice as to the optimum way to power that setup to reduce noise? I was thinking of powering the entire stack using the 5V J3 jumper on the MA and then shorting J4 1-2 3-4 (not exactly sure how to do that yet...).

But reading through the last few pages (and your post above) on this thread this will pass through RPi noise to the ProtoDAC correct?
If I'm wanting to use the MA, do you suggest I use a Zero W to minimise noise? I see from your signature that you use a Zero W. Do you find that WiFi interferes with/creates noise at all?

@wolf7250 yes thats what @hifinet is suggesting, to use ZeroW. Otherwise you'll have to have PurePi, lift the RPi3 a bit higher so that it doesnt use the ultracapacitors to power it (and use a separate 5V external power supply). On the shorting thing, you should get 3 small square black caps that you insert on top of the pins 1-2, 3-4 to short. Its shown in the FifiMa manual.

(01-29-2024, 04:49 AM)hifinet Wrote: With the FifoPi MA and ProtoDAC, the PurePi is not needed, since the 3.3V supply will not be needed. You just need the 5V component of PurePi, which (according to the manual) is the ConditionerPi. When you add the J4 jumpers, everything will run on 5V. Read the posts by @michaelagiles who has personal experience with the MA.

I think the UcConditioner Mk II 5V would be a better choice, but that should be up for discussion. Figuring out these Ian components and functionality from the manuals is a difficult task.  

I am currently using the 5V supply of PurePi with my 5V stack (Zero W/Allo Kali/ProtoDAC). I personally like the sound of the ultracapacitor supply very much. The best deep bass I have heard from my system. Very localized and accurate bass. The supply is very stiff, very low noise, accurate with a lot of detail. One friend does not like the sound of ultracapacitor supplies, because the sound has a "lack of body and pleasant dynamic bloom". "Unnaturally stiff sounding."

The Zero W works well with a local SSD USB drive. It did not work very well when connected to my large music library with -60dB WiFi signal and frequent library additions, which resulted in very long library updates.

• Pi Zero W, FifoPi MA, ProtoDAC, and UcConditioner Mk II 5V or
  
• Pi (any version), FifoPi Q7, ProtoDAC, and PurePi II with 5V going separately to Q7 and ProtoDAC
  

(01-29-2024, 06:45 AM)wolf7250 Wrote:

(01-29-2024, 03:03 AM)varunach Wrote:

(01-29-2024, 01:44 AM)wolf7250 Wrote:

(01-28-2024, 07:52 PM)hifinet Wrote: You only need the one stacking header between the Q7 and ProtoDAC to prevent 5V from ProtoDAC feeding back to the 3.3V of the Q7 GPIO. Q7 isolates the topside isolated GPIO (J7) from the RPi. That is one of the things it does.

The noise is primarily conducted noise that the RPi is imparting on all of the GPIO lines, power, grounds and I2S, the entire GPIO. Q7 isolates J7 from all this. EMI is much less, orders of magnitude less, IMO.

Yes, I am saying that if you are going to circumvent the isolation of Q7, you might as well save yourself some money and go with MA. MA also has two jumpers so that you don't need to use the stacking header. See the previous posts of @michaelagiles . The solution in that case is to use an RPi that emits less noise. The RPi Zero W would have the least of the current RPi in that regard, since it is single core. In my experience, Zero W is less noisy than RPi 2, which is less noisy than RPi 3.

@hifinet I recently ordered one of your kits on EBAY and was intending to use it with the FiFoPi MA and a Raspberry Pi 3B+. Would you have any advice as to the optimum way to power that setup to reduce noise? I was thinking of powering the entire stack using the 5V J3 jumper on the MA and then shorting J4 1-2 3-4 (not exactly sure how to do that yet...).

But reading through the last few pages (and your post above) on this thread this will pass through RPi noise to the ProtoDAC correct?
If I'm wanting to use the MA, do you suggest I use a Zero W to minimise noise? I see from your signature that you use a Zero W. Do you find that WiFi interferes with/creates noise at all?

@wolf7250 yes thats what @hifinet is suggesting, to use ZeroW. Otherwise you'll have to have PurePi, lift the RPi3 a bit higher so that it doesnt use the ultracapacitors to power it (and use a separate 5V external power supply). On the shorting thing, you should get 3 small square black caps that you insert on top of the pins 1-2, 3-4 to short. Its shown in the FifiMa manual.

@varunach thanks. I think that all makes sense.
Yeah I can see the small square black caps in the manual. Not sure if those are standardised and where I would find them. I could ask Ian Canada....

(01-29-2024, 03:37 PM)hifinet Wrote: The UcPi Universal Ultracapacitor power supply looks interesting. Since the ultracapacitors are preinstalled, that seems like a better value. The design is interesting or odd. It has the spring contacts for the RPi on the opposite side shown in the picture. So if you add your stack as described in the manual, the board would be flipped over (ultracaps on the bottom) and this also puts the ON/OFF switch as well as the green terminals on the bottom side. It seems better to use it as a standalone board without your stack mounted on it as designed. I guess the green terminal could be desoldered and moved, maybe the switch as well.

"Pi (any version), FifoPi Q7, ProtoDAC, and PurePi II with 5V going separately to Q7 and ProtoDAC" You meant 5V separately to RPi and ProtoDAC. Q7 requires 3.3V. This should be the better option of the two.

It's very nice that the clocks can be changed on MA.

(01-29-2024, 06:06 PM)hifinet Wrote: Regarding power supplies, I am planning to build a 5V 2S 18650 LifePO4 supply using this Ali BMS and my favorite linear regulator (LT1963, this module needs a general purpose 10uF cap added to the output, DS recs 10uF 50mOhm to 3 Ohm ESR). I think it can be built for <$20.

Hoping to answer the question: What is the difference in sound quality between a low ESR ultra cap PS and low ESR LifePO4 PS?

The added linear regulator might add its own sound character, but no other way to get 5V from 6.4V.

(01-29-2024, 06:06 PM)hifinet Wrote: Regarding power supplies, I am planning to build a 5V 2S 18650 LifePO4 supply using this Ali BMS and my favorite linear regulator (LT1963, this module needs a general purpose 10uF cap added to the output, DS recs 10uF 50mOhm to 3 Ohm ESR). I think it can be built for <$20.

Hoping to answer the question: What is the difference in sound quality between a low ESR ultra cap PS and low ESR LifePO4 PS?

The added linear regulator might add its own sound character, but no other way to get 5V from 6.4V.