Allo Boss to be fed with external 5V

[knudsen]

[danielfelix]

As I said, I am not an expert, but I saw in several designs of PSU this type of filter C + L + C. Simulate it in Multisim and it really works. Flatten the ripple considerably.
The voltage drop is very small, in my case 0.05V approximately, my instruments are not very accurate. I have 5.18V on pins 1 and 15 of Boss J2.
The inductance is recycled from a PSU of a PC.
I have also seen the type C + R + C, where R is 2 ohms, I did not do so as the voltage drop is higher.
Regarding sound, which is what interests us, I can not be very objective but sounds great!

[capedory]

@danielfelix

… the independent PSU I am looking at what was published here:
https://sites.google.com/a/architekturkonsulat.at/mdxs/resources/x-6
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… .

Hi Objectivist,
We think the suggested 2x9V@80VA transvormer in the above mentioned link is not badly designed. It prevents excessive heat dissipation in the regulator circuits and is based on the following calculation:
9V is the effective output voltage of the transformer when hooked up to 230 volt.
Effective voltage in AC represents more of an average (DC equivalent) than the actual wave … something like that

The crucial detail here is the fact that the peak amplitude (1) of the AC wave is not equal the effective voltage (3).
The game changer for the “9V” transformer is the smoothing capacitor behind the bridge which charges almost to the peak amplitude voltage (Û=Ueff√2)

9√2 = ~12,7V - ~1V (for the bridge) = 11,7V**
The pre-tracking regulators or the great SuperTeddyReg we use in out builts need an input voltage 5V higher than the output voltage of 5V. The 11,7 V give us ample headroom for that.

** Given the big transformer (80VA) we use and the small current a Pi and a DAC need there is no significant voltage drop in our settings.
Kind regards,
the mdxs team

[martin_h]

@mveldman

@Silentioso

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 !
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.

Hi Mveldman,
if the supply connects “hardwired” from the dac to the pi there will almost not be something like “what is left”. Because there is no separation. Separation only comes through designated regulators.
Kind regards
Martin

[mveldman]

@martin h

@mveldman

@Silentioso

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 !
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.

Hi Mveldman,
if the supply connects “hardwired” from the dac to the pi there will almost not be something like “what is left”. Because there is no separation. Separation only comes through designated regulators.
Kind regards
Martin

I fully understand, Martin.
In the meantime i have put an Allo Isolator between the Boss and the pi.
I use the linear PSU to power the DAC, i had to crank it up to 6 volt, and an iPad charger to power the Pi.
The sound quality dramatically improved!

[martin_h]

@mveldman

I fully understand, Martin.
In the meantime i have put an Allo Isolator between the Boss and the pi.
I use the linear PSU to power the DAC, i had to crank it up to 6 volt, and an iPad charger to power the Pi.
The sound quality dramatically improved!

[/quote]

[/quote]
Hi Mveldman, i’m happy to hear that!
It all starts with clean and silent power…
Kind regards
Martin

[fred9000]

hello mveldman , i saw you have the isolator with allo boss i suppose is it the 1.2 , is there limitation when you play some dsf files with the isolator vs not ? i ask the question because i did not try it yet

also how you plug all the setup , it make 3 plug , i curently make a diy box with toroidal transfo and i want to know hot to blug all the 3 ( rpi + isolator + allo boss 1.2 , i can’t wait to hear the sound

thanks

[mveldman]

@fred9000

hello mveldman , i saw you have the isolator with allo boss i suppose is it the 1.2 , is there limitation when you play some dsf files with the isolator vs not ? i ask the question because i did not try it yet

also how you plug all the setup , it make 3 plug , i curently make a diy box with toroidal transfo and i want to know hot to blug all the 3 ( rpi + isolator + allo boss 1.2 , i can’t wait to hear the sound

thanks

Hello Fred

The Boss is the first version, rev 1.2
The isolator is also the first version.
I am powering the set with a switching power supply for the pi and a Linear Power Supply to power the isolotar thus powering the Boss.
I have no idea if there are limitations with dsd files, i don’t have them
Playing 32bit 96khz however files are played without stuttering
In the meantime i have replaced my pi 3 by a pi3b

Mark

[Greyman]

I decided to go for the Allo Boss V1.2 rather the the Piano & Kali as I don’t currently have the time to look & learn Sigma Studio & trawl thru Mini DSP’s articles on DSP filtering etc. The Boss is a fine DAC, I was really impressed at the level of performance for the cost ! I had planned to build a dual linear PS for the Pi & Boss, however, I decided to try the quick & dirty (not really the right term to use when talking about PS !) by powering the Boss via a phone power bank (Case Logic 2,4A one). Well, the results are extremely good for such an easy upgrade, like another veil had been lifted & everything slightly better etched with more depth. Even internet radio (MP3) which I listen to while sat at my computer has gone up a notch or two ! My only complaint is WHY do so many manufactures use various USB connectors for power ? To me a USB connector is an I/O connector not a power connector, to the point that I understand the Pi 4 has fallen foul of this odd choice. I now don’t think I’ll worry about buying an Allo isolator but put the money towards a Katana !
Well done Allo for making such a fine, very cost effective device ! Highly recommended !
Best regards
A

[michel8166]

I recently also soldered the allo boss 1.2 (latest version) directly to the 5 volt input and there is a little change in the sound but not much.

I also have the allo isolator v1 in between, it is powered by a 12 volt battery.