Allo Boss DAC 1.2 Performance

Allo Isolator or Ian Isolator Pi

The BOSS is sitting on an Ian Isolator-Pi

Greg did you ever do an A/B with and without the isolator? I wonder if there is an advantage of going with a same brand (Allo Isolator) with the BOSS 1.2 or using Ians?

I'm getting good results with a naked Boss 1.2 and a cheap Linear supply powering both the Pi and DAC. I hope to use two supplies one for each in the future but my next step is the Isolator, I'm just wondering if it's worth it.

I've heard a lot of opinions about investing in a good linear supply is more worthwhile, making noticeable and positive changes in comparison to the Isolator and some saying the Isolator introduces jitter? Not sure about that though...
 
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@smallangryboy,

I honestly don't remember if I tried it without an Isolator. By the time the Boss 1.2 came out, I had tried every other RPi DAC I had with either Ian's or Allo's isolator and preferred all with them in place. I did also slightly prefer Allo's over Ian's... I assume it has to do with theoretically better regulators on Allo's.

I do have a friend who prefers the Boss 1.2 without an isolator. I can see if I can get more details from him. BUT he's also recently done a bunch of listening to various combinations of power supplies and a few configurations of the Katana AND prefers it with the Isolator 1.2. Go figure!

On an isolator board and jitter, no question that the devices used to produce the isolation add jitter to the I2S signals. That will vary depending on the specific isolator chip used... some are bad, some are ok, I've heard that some are very good. BUT the questions are:

1. How immune the target DAC chip and it's configuration are to the added jitter?

2. Is the negative impact of the added jitter larger than the positive impact of having separate grounds between the I2S source and the DAC board?

3. Can you use reclocking to reduce or elminate the jitter hit?

4. How good (low-jitter and low-noise) is the I2S source?

The RPi is a moderately to pretty noisy source (IMHO, based on the the power supply used) and unless it is being used in master mode (like with either of the Boss DACs, the Katana, and the HiFiBerry DAC+Pro series) is pretty jittery. In situations other than master mode DACs, an Allo Kali does a good job of cleaning up the inherent RPi jitter, especially when paired with an isolator to limit the effect of RPi processing noise on causing more jitter.

Using a quieter power supply with a low output impedance over a very broad frequency range (like a Salas shunt regulator) on the RPi does reduce the noise from its processing. So using a supply like that should lower the relative benefit of an isolator. AND to be honest, I haven't done ANY comparisons with supplies such as this.

Finally, some DAC chips running in master mode AND configured well, is generally more immune to incoming I2S jitter. That configured well is important, it is not inherent with master mode.

I found I preferred the Boss 1.2 without a Kali... some of the magic that had me admire and enjoy the Boss 1.2 without a Kali is lost after adding a Kali, even though in some ways it sounds better.

BUT I can't answer your question of isolator or note... partly because I didn't do it, and partly because it will depend on your specific setup.

SORRY!

Greg in Mississippi
 
Thanks Greg for the in depth reply, it was helpful.

It is very small margins I guess at this point. Interestingly I had to use a linear supply with the Boss 1.2 to beat a naked ChromeCast Audio - well to my ears anyway. I figure unless you have two identical setups a comparison would be awkward and I'm never going to have dual linear supplies to do any worthwhile A/B testing with and without the Isolator.

My hunch is to go with the Allo Isolator and then remove it if I think it's masking anything.
 

Hummer981

Member
2019-04-14 7:48 am
Thanks Greg for the in depth reply, it was helpful.

It is very small margins I guess at this point. Interestingly I had to use a linear supply with the Boss 1.2 to beat a naked ChromeCast Audio - well to my ears anyway. I figure unless you have two identical setups a comparison would be awkward and I'm never going to have dual linear supplies to do any worthwhile A/B testing with and without the Isolator.

My hunch is to go with the Allo Isolator and then remove it if I think it's masking anything.

I have the Boss 1.2 and added the Isolator 1.3 and am not sure it benefits the Pi + Boss DAC. It seems to have lost a little bass and generally sounds a little more restrained.

Another aspect of the Isolator which is not good is that it only lets you use 32/192khz material whereas previously I was getting very good results from the Boss upscaling to 24/32/384khz. The sound was I feel better in this configuration with the boss without the Isolator. I am confined the benefits of upscaling out weigh the benefits of the isolator especially as it limits the upscaling capability.
 
Hi,

Not sure whether this is the right thread to ask my question. But it seems like there is some expertise on powering Allo Boss here.

I am building a dual linear psu for my rpi + allo dac.
One supply is for pi the other for the dac. All should go into (reasonably) nice box with a 2 lines LCD display (box not tall enough for mire lines) to show played song.

I would like to feed 5V directly to the boards, bypassing the usb connectors.
I understand the I can feed Boss through GPIO 1-15. Is pin 1 connected to pi's 5V line when the jumper separating dac's and pi's power lines is OFF? Probably not, but I want to make sure.
Is there any way of accessing Rpi's 5V line with the dac hat on?
Normally one can feed the Rpi throught its pins 2,4(5V) and 6(GND).
Maybe I can use one contact of the jumper which controls whether the devices are feed from one PSU of separately. As the jumper is now OFF, maybe one pin of the jumper is Pi's 5V and the other DAC's 5V?
 
Hi Everyone,
I just got my Allo Boss. I paired Allo Boss with MoodeAudio and I was pretty happy with it.

Then I tried my hands on piCorePlayer after hearing so much about it on the forum. I am hearing some noise from my speakers when the volume is high. At high volume bass from speakers gets distorted (Above 85%). Till 85% is perfectly fine. Is this normal?

I am using Alsa equalizer and Bass preset to increase the bass.

My Amplifier is a very generic one, have modified it by adding Nichicon 4700uf 35v decoupling caps, which improved my sound quality a lot. Speakers are JBL Studio 230BK.

48140726067_0ce4d1fa95_c.jpg


I am using OnePlus Dash charger rated at 5V 4A with Dash charging USB C cable to power my Allo Boss and Xiaomi 10000 Mah power bank rated at 5V 2A to power my Raspberry Pi.

Am I doing anything wrong here? Or I am expecting too much from the system.

Please help me with this.

Thanks,
Simar
 
Just to add in, the problem seems to be with output from Allo Boss only. I increase volume to 100 from MoodeAudio or piCorePlayer and keep amplifier at low volume, there is distortion from the speakers.

If decrease the volume on MoodeAudio or piCorePlayer say to 90, and increase amplifier volume, the sound is clear.

It's almost the same for MoodeAudio and piCorePlayer. I am using the equalizer on both to boost bass.

Is this normal? How can I improve on this, if possible? Is Equalizer (Bass Boost) the culprit here?

Thanks,
Simar
 
This has nothing to do with Moode or pCP or any other OS.
They all use the same platform.

1. It's not a good idea to boost the low end with such a small amp
2. Make sure that the amp can handle 2V on the input

Check your Boss mixer settings.

Turn off 'Analogue Playback Boost' (0%)

Try to toggle the "Analog" mixer:

@ "0%" Boss outputs 1V max.
@ "100%" Boss outputs 2V max.


Equalizer and any other DSP can also add noise to the signal.

Good luck.
 
Thank you for the help SoundCheck, these are my settings as suggested by you on your blog.

48141821896_f4e7d0e0df_c.jpg


48141911627_1b111dab39_c.jpg


Where to turn off Analogue Playback Boost?

I have always kept my settings to 0db only. With "Analog" mixer toggle you mean to set Output Level? Or the "Simple Mixer Controls"?

Also, do I need to change ALSA volume control to "Digital" in Squeezelite settings?

Sorry little bit new to this field, still learning. Can you please help me with this.

Thanks,
Simar
 
Are u using the latest pCP5 with audio kernel? If not run the upgrade first.

With the old version all kind of weird parameter changes were happening.


Actually your settings do not 100% match my recommendations.

* Alsa setting
65536 instead of 80

* Filter
Ringing Less Low latency FIR

* DAC volume control
-V "Digital"

("Master" would be Piano 2.1 and Katana)



The "simple mixer controls" look about right.
* Your Dac outputs 2V now.
* If you turn off "Toggle 6dB...." the DAC delivers just 1V max.



Beside that I recommend to feed Boss and Piano with 352k8/384kHz upsampled material to avoid the internal DSP/filters.
 
Hi,

Not sure whether this is the right thread to ask my question. But it seems like there is some expertise on powering Allo Boss here.

I am building a dual linear psu for my rpi + allo dac.
One supply is for pi the other for the dac. All should go into (reasonably) nice box with a 2 lines LCD display (box not tall enough for mire lines) to show played song.

I would like to feed 5V directly to the boards, bypassing the usb connectors.
I understand the I can feed Boss through GPIO 1-15. Is pin 1 connected to pi's 5V line when the jumper separating dac's and pi's power lines is OFF? Probably not, but I want to make sure.
Is there any way of accessing Rpi's 5V line with the dac hat on?
Normally one can feed the Rpi throught its pins 2,4(5V) and 6(GND).
Maybe I can use one contact of the jumper which controls whether the devices are feed from one PSU of separately. As the jumper is now OFF, maybe one pin of the jumper is Pi's 5V and the other DAC's 5V?

Greg,

IMHO, directly accessing the 5V for both the RPi and the Boss 1.2 AND bypassing the micro-USB and USB-C is a good idea. For the RPi micro-USB, while I've not tried it myself, I've seen reports of that being an improvement from others. That's why I went to that type of connection when I first started using RPis. AND I did bypass the USB-C on my Boss 1.2 and found it a mild upgrade.

For the Boss, accessing the RPi and Boss 1.2 5V is pretty easy using pins on the Boss J25 and J19:

- For powering the Boss DAC, the pin of the J25 jumper closest to the edge of the board is the Boss 5V. I just soldered a connector directly to that pin and the ground side of the connector to the shell of the USB-C connector (see picture).

- For powering the RPi, the other pin of the jumper, the one towards the center of the board, is the RPi 5V. You can access that there. Also you can use the ground and 5V pins on the J19 header. They are directly connected to the RPi 5V and ground and with the J25 jumper off they are NOT connected to the Boss 5V.

Some of this is covered in the Boss 1.2 Tech Manual, but not all.

Sorry for the slow response, I had lent out the Boss 1.2 I have here and knew it was coming back. I wanted to have it in my hands and be able to confirm everything before I posted.

Also, in my experience, the Boss 1.2 works ok if both the DAC and RPi supplies both come up at the same time.

I hope that all helps!

Greg in Mississippi

P.S. As I've posted here and on other forums I was and am really impressed with the Boss 1.2. It is IMHO the best implementation of a PCM51x2-based RPi DAC, especially powered well and using an Isolator board. After the original Boss came out, I was similarly impressed with it and found it beating my highly-modified HiFiBerry DAC+Pro. So I got another original Boss with the intention of modifying it for even better SQ. THEN before I got to that project, Allo introduced the 1.2 version. It was sufficiently good that I dropped any intention of trying to make it better! In my experience, you have to get to a DAC board with separate output stages which are separately powered (or good transformers) to better this.
 

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Thanks Greg!

I have figured out some of what you have written up myself.
Anyway it is reassuring to see this written by somebody with more experience before fry my RPi or Boss.

For now I am still using micro USB for Pi and USB-C for Boss. But I will probably change at least feeding the Boss.

Yesterday I spend spent time with multi meter poking around voltages to understand jumpers and Boss connectors. I connected a small 2 line (my enclosure is pretty slim) LCD screen.
 
Greg,

IMHO, directly accessing the 5V for both the RPi and the Boss 1.2 AND bypassing the micro-USB and USB-C is a good idea. For the RPi micro-USB, while I've not tried it myself, I've seen reports of that being an improvement from others. That's why I went to that type of connection when I first started using RPis. AND I did bypass the USB-C on my Boss 1.2 and found it a mild upgrade.

For the Boss, accessing the RPi and Boss 1.2 5V is pretty easy using pins on the Boss J25 and J19:

- For powering the Boss DAC, the pin of the J25 jumper closest to the edge of the board is the Boss 5V. I just soldered a connector directly to that pin and the ground side of the connector to the shell of the USB-C connector (see picture).

- For powering the RPi, the other pin of the jumper, the one towards the center of the board, is the RPi 5V. You can access that there. Also you can use the ground and 5V pins on the J19 header. They are directly connected to the RPi 5V and ground and with the J25 jumper off they are NOT connected to the Boss 5V.

Some of this is covered in the Boss 1.2 Tech Manual, but not all.

Sorry for the slow response, I had lent out the Boss 1.2 I have here and knew it was coming back. I wanted to have it in my hands and be able to confirm everything before I posted.

Also, in my experience, the Boss 1.2 works ok if both the DAC and RPi supplies both come up at the same time.

I hope that all helps!

Greg in Mississippi

P.S. As I've posted here and on other forums I was and am really impressed with the Boss 1.2. It is IMHO the best implementation of a PCM51x2-based RPi DAC, especially powered well and using an Isolator board. After the original Boss came out, I was similarly impressed with it and found it beating my highly-modified HiFiBerry DAC+Pro. So I got another original Boss with the intention of modifying it for even better SQ. THEN before I got to that project, Allo introduced the 1.2 version. It was sufficiently good that I dropped any intention of trying to make it better! In my experience, you have to get to a DAC board with separate output stages which are separately powered (or good transformers) to better this.

thanks for the explanation:) and indeed it improves slightly but not much.
by the way I have under the allo boss 1.2 the allo isolator v1 fed by a 12 volt battery which also adds some improvement / change.
anyway I am still very satisfied with this setup.