Allo Boss to be fed with external 5V

What are the electrical specs to feed the Boss externally:

  • Voltage with tolerances +/-
  • Input current @5V


n.B.: I’m thinking to use 3 or 4 batteries with 1,5V

I also want to know the Allo Boss external 5V socket spec.
Is it used 1.5mm pitch?

Did someone use external 5V to power up Allo Boss and found improvement?
I have purchased 5V 5A brick power supply and looking for split the RPi3 and Allo Boss input power.

Thanks all.

I started with a battery to replace my standard iPad charger and found the sound slightly better.
So wanted this sound to be permanent .
I decided to build this PSU
Now i have it running for about 4 months and i like it a lot.
And the sound is absolutely better, not only since i build the PSU myself :wink:
Oh, i forgot to mention: the PSU is feeding the Allo Boss direct and through the Boss the Pi is powered.

I’m behind the same search.
The idea is to feed with independent PSU the Rasp3 and the Boss.
That’s what these instructions are for:
For the independent PSU I am looking at what was published here:
This circuit I simulated it in NI Multisim 14 and I think it is badly designed the transformer, it should be 12 + 12 according to my appreciation.
If you are interested, I can publish the simulations and diagrams.
The big question is whether it really is necessary to use such elaborate sources. Now I use a single power supply for both 5V 3A components and it works beautifully.

I think this is way to go. Start with a clean powersource at the most critical part; the DAC. It is fine that the other parts like the Pi are feed through the DAC with the ‘leftover’ power as these are much less critical.

Feeding the Pi independently does not seem to have any benefit, just more wires and PSU’s that can generate magnetic fields and other polution. Less is more I think.

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Hi Mveldman, how did you connect the battery to J4 socket?
Just hack on by jumper wire?

So, you are using 5V 3A power supply connect to RPi3 ONLY?

That’s an interesting attempt!

Does it really make a (hearable?) difference to feed the player by RasPi USB connector or by BOSS’s terminals?

Do I have to make any changes if I feed throug th BOSS?

A good PSU makes a different.
The “good” power is first going to the Boss and what is left goes to the Pi.
So this approach is clean power for the Boss, what results in a better sound quality.
To be honest, the audible difference is not that big, which means that Allo did a great job, or that my old ears are beginning to let me down :wink: !
For feeding the Boss and the Pi this way you does not have to do anything, works out of the box, no desoldering or so.
This was one of the reasons for me to choose this solution.

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Thanks mveldman

Yes, RPi and Boss food from the mini USB of the RPi.

Hi @mveldman, so what you do is feed Boss and RPi3 from terminals 2 and 16 of Boss.
Without desolating anything from the Boss.
In this way the Boss takes the necessary energy from the source and the RPi3 is fed with “surplus”. It is right?

I’m not to answer for mveldman, but I think the answer is yes… I just did it, took 5 minutes to cut an unused usb-cable open and solder the red (5v) to the pin at the one end (the “S” end of the letters BOSS) and the black (ground) to the other (B end of BOSS). I used the pins closest to BOSS, I guess they are 1 and 15; I believe I’ve read someone using both 1+2 and 15+16 to get the best connection. I’m using a small powerbank for testing, I’ve used Allos 3A until now.

I’m hearing BIG improvements. Most obvious is much more bass, almost too much, but I’m hopefully going to roomcorrect when I get a mic. But everything else too, much better imaging, its on a whole other level to me.

Though just before I did this I did everything in this thread (using rune at the moment), I believe that gave a lot too but not as much as the power thing. Another explanation would be that all those software tweaks were not activated until I unplugged it completely, but since I restartet many times during the tweaking I doubt that.

Gonna check tomorrow too, to be sure my ears are not deceiving me… :wink:

As knudsen said: that is exactly what i have done!

Well, I keep the subject. Instead of feeding the Rasp + Allo Boss set from Rasp., I now do it from pins 1 and 15 of Boss JP2.
I attach the Daqarta captures. From what I see there is a considerable improvement in noise.

Great work Daniel :smiley: Sorry for noob question, but how do you judge the noise is lower? I see the amplitude on the top right is much lower than left, is that relevant?

Still enjoying battery on 1 and 15, and still hear it as better, though the battery only gives 4.8V across those pins so maybe not optimal. I feel its a jungle with this power stuff, Ifi, linear power supply, switchmode through LT3045 (as here), batteries of various kinds combined with regulators and what not. I think I lean on getting the Allo Isolator fed by Ifi 9V, and the original allo smps to the pi (though I’ve seen nothing on the Isolator fed by non-battery)

I am an electronics enthusiast, although I worked for years in that profession my knowledge is not that of an expert. So I wait for the opinion of the experts to continue learning.
First I answer the question about noise. In the oscillograms it is seen that the noise is of an aplitude of + -200mV in the case of feeding from Rasp and + -140mV fed from Boss
This was an approximation to the problem using standard switch PSU. I dropped this since I had only 4.8V at the output.
Then I found a specific PSU 5V 3A for Rasp. and did some tests.
First I did an analysis loading the PSU with a resistor of 22 ohms, these are the graphs obtained:


We see that we have approximately a noise of 10mV
I thought about how to improve that and tried to filter out the PSU. I used this circuit:


Where V1 is the PSU and R1 is the charge, in this case 22 ohms resistor.

The analysis gives me the following graph:


here we see a waveform of no more than 1mV, fantastic! It remained to see what happened connecting everything to the set Rasp + Boss. In fact already had decided to do it via pin 1 and 15 of JP2 of the Boss.



We see the waveform obtained:


10 mV, perfect for me!

and the sprectrogram: