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First impressions
#11
To change the SoX settings, you go back to disabled, save and MPD will restart.

My system consists of the Boss (actually just in the last week I stepped up to the SMSL Sanskrit 10th MkII based on recommendations in the hardware forum - clearly better than the Boss, and sounds better without SoX based on limited listening time) directly driving two Icepower 500ASPs as monoblocks (250W each into the speakers; these have taken over for a pair of self home built tubes amp monoblocks 70W each - the Class D amps have much better bass and the tube amps much better treble, midrange similar) driving a pair of Harbeth Super HL5. The music I listen to is entirely acoustic, classical orchestral/choral or baroque ensembles. I very infrequently attend live concerts, and when I do I will spend the money for the best seats I can get, which are middle section, orchestra level row 5-15. So I think that stereo reproduction needs to fool the perception of a live orchestra. The new high quality, inexpensive DACs can do this to a large degree. That being said, I have never heard a stereo system at any price that can accurately reproduce the sound of a bass drum, 32' pipe or cymbal.
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#12
(06-27-2020, 05:52 PM)Griff Wrote: Hey all,
So I recently got myself into the RPI/DAC audio world. Got myself a RPI4/AlloBoss1.2 and it's feeding to an Allo Boss Volt+ D Amp which is feeding a pair of B&W 686 or B&W 705s. 
Did you recieve your Boss after Corona lockdown?  Im waiting for mine for more then a month now...don''t get any response Sad
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#13
@hifinet
I tried a SMSl Sanskrit 10th Mk2 in my system but couldn't get Moode to see it. Are you using it via USB? Any special settings?
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#14
(06-29-2020, 05:41 PM)jonners Wrote: @hifinet
I tried a SMSl Sanskrit 10th Mk2 in my system but couldn't get Moode to see it. Are you using it via USB? Any special settings?

Same thing happened to me. Searched on the forum here and found the answer. You need to make sure the input on the SMSI is set to USB (U1). Then it will be recognized in the MPD settings as "USB audio device". I think when I first tried I must have inadvertently hit the power button twice, and it switched to U2 input.
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#15
(06-28-2020, 07:52 PM)Griff Wrote: It's interesting.... so today I listened to a few albums, Daft Punk, Radiohead.... LCD Soundsystem, Zeppelin, Goldffrapp, Beatles.... eyes closed... listening intently and ... for me... I found that with Sox turned on there was a lack of low end compared with off. I also found better stereo separation with it off..... Sox on seemed to deaden the sound a bit for me. Without was that bit livelier.... 

So I'm mostly listening to acoustic classical. More complex sound with direct sound and hall reverberation. As philrandal said that the soundstage is better defined. Instrument placement is better. I actually think the "livelier" sound you are describing is distortion. The lack of low end is something I have not experienced.

I don't know how you are powering the RPI/Boss, but for me using an Aukey USB C 20000mAh battery made world of difference, especially in the bass. Highly recommend a battery instead of a power supply. Connected it to the Boss with the jumper on, so it powers the RPI and the Boss. You can play it for over 12 hours. The sonic results are much better than a 5V 20A lab grade Acopian linear power supply that I was using.  I also tried two batteries, one to the RPI and the other to the Boss with the jumper off. Never could get it to work. It's possible that the voltages of the two batteries were very different. The correct method is to power the Boss and then the RPI in this setup. On retries it eventually broke the SD card. Reflashing is easy, but I have a huge music library of over 1TB, so it takes a long time to rescan.
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#16
(06-30-2020, 02:31 AM)hifinet Wrote:
(06-28-2020, 07:52 PM)Griff Wrote: It's interesting.... so today I listened to a few albums, Daft Punk, Radiohead.... LCD Soundsystem, Zeppelin, Goldffrapp, Beatles.... eyes closed... listening intently and ... for me... I found that with Sox turned on there was a lack of low end compared with off. I also found better stereo separation with it off..... Sox on seemed to deaden the sound a bit for me. Without was that bit livelier.... 

So I'm mostly listening to acoustic classical. More complex sound with direct sound and hall reverberation. As philrandal said that the soundstage is better defined. Instrument placement is better. I actually think the "livelier" sound you are describing is distortion. The lack of low end is something I have not experienced.

I don't know how you are powering the RPI/Boss, but for me using an Aukey USB C 20000mAh battery made world of difference, especially in the bass. Highly recommend a battery instead of a power supply. Connected it to the Boss with the jumper on, so it powers the RPI and the Boss. You can play it for over 12 hours. The sonic results are much better than a 5V 20A lab grade Acopian linear power supply that I was using.  I also tried two batteries, one to the RPI and the other to the Boss with the jumper off. Never could get it to work. It's possible that the voltages of the two batteries were very different. The correct method is to power the Boss and then the RPI in this setup. On retries it eventually broke the SD card. Reflashing is easy, but I have a huge music library of over 1TB, so it takes a long time to rescan.
I own a BOSS card. I had experienced the RPi's system restarted periodically when the 5V power was not injected from the RPi4's USB C connector. I guess the problem is due to the 5V power being brought to the bottom side of the PCB with a few small VIA holes since the surface mounted 40-pin dual row pin header is mounted on the back side of the board. This is the reason I avoid to use the SMT 40-pin header in my design. If I chose to use SMT pin header, I would use bigger diameter VIA holes and put more VIAs on the board. It is the misleading information that linear power supply should be prefer for audio design. Linear power supply always carries trace of 50/60Hz from the power line which is difficult to get ride of. Switching power supply has its own advantage that the high switching frequency is easy to filter. If you look at the inside picture of the SMSL Sanskrit you have (Amazon shows the picture), you can find the small dual rail DC-DC converter under the subtitle "Built-in high-performance power". The filter is LC filter. The silver color capacitors are aluminum hybrid polymer type. Some audiophiles use the brand name OS-CON to represent it. This type of electrolytic cap has very low ESR. They are not cheap for its small capacitance. The DC-DC converter is also used to create an isolated analog ground plane. The noisy digital ground plane is due to the fast parallel bus DRAM access. So, if the DC-DC converter's dual rail output has its own ground reference, the noise on the dual analog voltages will not be affected by noisy digital ground plane.
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#17
(06-30-2020, 02:11 AM)hifinet Wrote:
(06-29-2020, 05:41 PM)jonners Wrote: @hifinet
I tried a SMSl Sanskrit 10th Mk2 in my system but couldn't get Moode to see it. Are you using it via USB? Any special settings?

Same thing happened to me. Searched on the forum here and found the answer. You need to make sure the input on the SMSI is set to USB (U1). Then it will be recognized in the MPD settings as "USB audio device". I think when I first tried I must have inadvertently hit the power button twice, and it switched to U2 input.

Thanks, it's working.  Smile
I appears to default to U2 when it's powered up!
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#18
efung

Quote:Switching power supply has its own advantage that the high switching frequency is easy to filter. If you look at the inside picture of the SMSL Sanskrit you have (Amazon shows the picture), you can find the small dual rail DC-DC converter under the subtitle "Built-in high-performance power". The filter is LC filter. The silver color capacitors are aluminum hybrid polymer type. Some audiophiles use the brand name OS-CON to represent it. This type of electrolytic cap has very low ESR. They are not cheap for its small capacitance. The DC-DC converter is also used to create an isolated analog ground plane. The noisy digital ground plane is due to the fast parallel bus DRAM access. So, if the DC-DC converter's dual rail output has its own ground reference, the noise on the dual analog voltages will not be affected by noisy digital ground plane.

Great info! Thanks for the explanation. At first it looked like a large film cap, but it was marked with an SMSL part number, with a 2W rating. Is it sealed in epoxy for ease of manufacture or to protect a proprietary design? When researching the DAC, I was very impressed that SMSL improved the Mark II from the first version by a significant margin, SINAD increasing from 101 to 114 dB, and increasing the price by only $10. Very satisfied with the purchase. Don't know why the manufacturer markings on the op amps have been removed. Previously a JRC version of the venerable 5532. The Topping E30 uses TI OPAs, better build quality and only $20 more. Probably a better value, but no USA seller stocks the unit.
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#19
(06-30-2020, 02:30 PM)hifinet Wrote: efung

Quote:Switching power supply has its own advantage that the high switching frequency is easy to filter. If you look at the inside picture of the SMSL Sanskrit you have (Amazon shows the picture), you can find the small dual rail DC-DC converter under the subtitle "Built-in high-performance power". The filter is LC filter. The silver color capacitors are aluminum hybrid polymer type. Some audiophiles use the brand name OS-CON to represent it. This type of electrolytic cap has very low ESR. They are not cheap for its small capacitance. The DC-DC converter is also used to create an isolated analog ground plane. The noisy digital ground plane is due to the fast parallel bus DRAM access. So, if the DC-DC converter's dual rail output has its own ground reference, the noise on the dual analog voltages will not be affected by noisy digital ground plane.

Great info! Thanks for the explanation. At first it looked like a large film cap, but it was marked with an SMSL part number, with a 2W rating. Is it sealed in epoxy for ease of manufacture or to protect a proprietary design? When researching the DAC, I was very impressed that SMSL improved the Mark II from the first version by a significant margin, SINAD increasing from 101 to 114 dB, and increasing the price by only $10. Very satisfied with the purchase. Don't know why the manufacturer markings on the op amps have been removed. Previously a JRC version of the venerable 5532. The Topping E30 uses TI OPAs, better build quality and only $20 more. Probably a better value, but no USA seller stocks the unit.

The epoxy sealed package is common in small DC-DC converters and named "potted". The SMSL part number means OEM in large quantity to lower BOM cost. I do the same too. The DAC chip used in the older Sanskrit 10th is the lower grade AK4490. The BJT input NJM2214 used in the older Sanskrit 10th is a cheap OpAmp. If you compare the sound quality with BJT input OPA1602, the NJM2214 sounds a little grainy. The noise of NJM2114 is 4x of the OPA1602 and its price is 1/4 of OPA1602. The Topping E30 uses OPA1612 and does not have isolated analog ground plane. This is my observation based on the PCBA image available online. The common markup multiple on BOM cost is 4x. That means, the increase in material cost is $2.5.
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#20
efung, again, thanks for the fantastic info. Is any generic (eBay) DC-DC converter adequate for isolating the ground plane? Do you have a product on the market?
NJM has been called "ghetto blaster" quality in the DIY community. Agree with the substandard sound quality. A few months ago I got a deal on Icepower modules 125ASX2. These were in VocoPro Feather amp FA-500 selling for $87 shipped in US clearance Beach Audio through NewEgg. The preamps in these were loaded with NJM op amps. Sound quality was substandard. Pulled the Icepower modules, trashed the rest of it.
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