[carlmart]

Looking around for OPA1612 impressions, I found this one, where a guy replaced the NE5532 on a Benchmark with the OPA1612:

"I just replaced all NE5532 amps in Benchmark DAC1 with OPA1612 and play it so far for few hours. NE5532 is a very good amplifier especially for the price ($0.5). OPA1612 is fuller sounding - especially lower midrange but also more dynamic. Transients are stronger, both rimshots of snare drum and big-band trumpets. It is a little bit cleaner and perhaps because of that instruments are more defined in space. A little improved width of the image and maybe slightly depth as well. NE5532 is very flat and even sounding but is no comparison to OPA1612. Overall balance with new amp is a little darker but with better transients. OPA1612 is open sounding but is a little warmer possibly because of the lower midrange roundness. So far I don't hear any harsh sibilants (very clean) but it is virtue of my speakers. What else, maybe cleaner more resolved sound at congested parts."

As we can't (shouldn't) repeatedly solder/unsolder an SMD IC, my idea is to find a point where it's possible to solder an output cable, and experiment with IC options (and regulation) outside the D50.

 

[BattousaiX26]

I have tested many different power sources with the D50 and was surprised with the differences. It is like a chameleon, depending on the power supply connected.
With the linear power supply the sound was most dynamic, had biggest and deepest soundstage but it was on the other side most aggressive with very upfront treble. Big expansive sound but very fatiguing.

With the battery pack the sound was on the opposite side, narrower soundstage but softer and darker. It is overall much more pleasant, probably slightly veiled. The problem with the battery pack or powerbanks is that you have to charge it over and over again and the sound is different when fully charged and when half-empty. Somehow the sound starts to deteriorate when the battery starts loosing the initial charge.

At last I have tried it with different power adapters I had around, until I found the chosen one. It was a 5V / 2.5A switching power adapter which came included with the SMSL M8a. Both my M8 and M8a are powered by SMSL own linear power supply P1, so the switching adapter was lying down unused in the box. It was the best compromise I could get, smaller soundstage than linear but less harsh, and overall more stable and consistent than the battery pack. I have immediately ordered one spare from Aliexpress for $8 incl. shipping. That's the cheapest you can get for a a decent performance. The plug fits perfectly for the D50 and has a ferrite choke on it.
If you want to order it, you can go to Aliexpress, drop a message to the seller that you need a SMSL M8a power switch. Since they don't list it separately, they will point you to order one remote control which costs exactly the same amount. After you put it in the cart, during the check-out before clicking the buy button, just write into the message field that you actually want the power adapter instead and that's it.
So I ordered this:
https://www.aliexpress.com/item/SMS...557.html?spm=a2g0s.9042311.0.0.2e694c4d1iRCH1

After that, I got the confirmation message that I am actually getting this:
"Hello, dear friend.
We have arranged for you to send the M8A European power adapter, please rest assured and patiently
SMSL Customer Service Team"

I think I will invest in a battery pack then. I love soft sound which is why I bought mojo, unfortunately not reliable so I have to settle for the d50 though I think I would not regret my decision. Out of the box it leaves a lot of good impression already especially on the vocals . I will need more time to evaluate the filters but my current favorite is the filter number 5, which in my memory sounds closest to what the mojo produces

 

[BattousaiX26]

This is the power supply I bought for my D50.

https://www.ebay.com/itm/323497118424

Even if I will only be back at home next week, tracking showed my D50 was delivered. The power supply might take longer, but not too much.

I already have another linear power supply I can try until the other gets home, even for comparison.

Thanks, I will check it out.

 

[bogi]

I was considering using this little board to assemble an USB isolator.

https://www.adafruit.com/product/2107

It is full speed (enough for UAC1) but not high speed (must for UAC2 and DSD). So it would support only PCM sample rates up to 96k.
Maybe iFi iDefender could be much more suitable isolation device than the one you posted.

Look also to the direction Vosya posted:

In my case, a positive effect caused by usb cable, which did not have a galvanic connection between the metal shields of plugs.

 

[carlmart]

Look also to the direction Vosya posted:

Which direction?

 

[bogi]

I meant to experiment with USB cable. Look at this picture, that's a custom made cable from Elijah Audio. The picture is taken from CA forum
https://www.computeraudiophile.com/...-usb-and-power/?do=findComment&comment=587079

Yellow is used for data - it contains DATA+ and DATA- wires. The detachable red one is power (VBUS +5V) and the black is ground.
It is known that some DACs don't need to have power and ground lines connected AFTER initial handshake with computer.
There are reports from users who point to increase in sound quality when ground is disconnected from computer. It's called 'ground lift'.
I don't know if ground lift works with D50, it's just an idea what IMO would have sense to try.

Look also here https://www.computeraudiophile.com/forums/topic/28604-usb-ground-lift/?do=findComment&comment=885132

 

[carlmart]

Bogi,

Thanks, that is a brilliant idea!

Making such a cable is not complicated, and I have to see how you actually do the ground lifting.

The schematic of what you have to do is this:

DAC PSU
+------+ +-----+
| +5V |---------------| +5V |
| GND |-----+---------| GND |
| D+/- |==# | +-----+
+------+ | |
| |
| | PC
| | +------+
| +--<SW>---| GND |
#============| D+/- |
+------+

I was looking at ways to isolate DAC and PC galvanically, but it seems it's not necessary. If you put transformers, you may have to add amplification.

 

[andrewinukm]

Looking around for OPA1612 impressions, I found this one, where a guy replaced the NE5532 on a Benchmark with the OPA1612:

"I just replaced all NE5532 amps in Benchmark DAC1 with OPA1612 and play it so far for few hours. NE5532 is a very good amplifier especially for the price ($0.5). OPA1612 is fuller sounding - especially lower midrange but also more dynamic. Transients are stronger, both rimshots of snare drum and big-band trumpets. It is a little bit cleaner and perhaps because of that instruments are more defined in space. A little improved width of the image and maybe slightly depth as well. NE5532 is very flat and even sounding but is no comparison to OPA1612. Overall balance with new amp is a little darker but with better transients. OPA1612 is open sounding but is a little warmer possibly because of the lower midrange roundness. So far I don't hear any harsh sibilants (very clean) but it is virtue of my speakers. What else, maybe cleaner more resolved sound at congested parts."

As we can't (shouldn't) repeatedly solder/unsolder an SMD IC, my idea is to find a point where it's possible to solder an output cable, and experiment with IC options (and regulation) outside the D50.

Check out the adaptor by Sparkos:
https://sparkoslabs.com/product/dip-to-soic-op-amp-adapter/

Why not just use a cellophane tape, and tape the 5V contact points in the USB to test it first? Then you can use whatever audiophile cables later.

If you want a USB filter, perhaps an iFi iPurifier3? I think this one is pretty good value for money. I use ISO Regen and the difference in sound quality is pretty significant.

 

[andrewinukm]

Here is a pretty crazy experiment from today, combining best aspects of D50 and UDA38.
For UDA38 that would be superior DAC chip and TCXO dac clock (though the TXCO looks big and fancy may not actually perform better than the D50s XO), for the D50 it would be IV and output stage.
Its destructive but fixable for the UDA with a couple cut traces and reversible for D50 (but on the risky side).
Just needs a couple wires to connect the 9038Pro chip outputs to the IV stage in the D50, only the amplifiers have power in the D50 which is the dual 16V supply (can confirm 16V sounds a bit better than 12V to my ears, plus replacing ceramic and tantalum caps with polypropylene helped a bit too).
I did this because there was very good chance it would sound better than either the UDA or D50 on their own and it absolutely does, sounds really fantastic. Its modding to absolute extreme but I only need 1 DAC and they were already too heavily modified to sell so why not.

Holy macaroni, Acke!
What an amazing franken-mod!

Are you able to figure the I2S signal lines from D50's USB XMOS to the DAC chip? I noticed I2S markings on some test pad.
Perhaps a great mod to upgrade the USB input is to franken-mod it with Luckit WaveIO as the USB receiver, and output I2S to D50 (or UDA).

It looks like the UDA uses OS-CON caps for the DAC chip. This is part of the magic. Lampizator's old site and DIYaudio is full of amazing mods to replace digital circuit caps with OS-CONs. Perhaps if space allows, replaceing D50's DAC chip caps with OSCONS could bring it closer to UDA's sound as well.

 

[carlmart]

Check out the adaptor by Sparkos:
https://sparkoslabs.com/product/dip-to-soic-op-amp-adapter/

https://sparkoslabs.com/product/dip-to-soic-op-amp-adapter/

As I said, I do not want to mess the D50 internals. That's in case I want to sell it.

Why not just use a cellophane tape, and tape the 5V contact points in the USB to test it first? Then you can use whatever audiophile cables later.

Of course I will experiment things first with any USB cable around. And I don't intend to buy any audiophile cable, I intend to DIY it myself. Cables prices get too crazy.

What I need to find out is what DIY people are doing with USB cables.

If you want a USB filter, perhaps an iFi iPurifier3? I think this one is pretty good value for money. I use ISO Regen and the difference in sound quality is pretty significant.

$129 for the iFi iPurifier3 might be good value, but it's a bit too much. Half the price of a D50.

 

[andrewinukm]

My mistake for not checking the iPurifier3's price first. iPurifier 2 was a lot cheaper when it was available, and I believe you could buy then 2nd hand for even cheaper.

I would suggest solid core cables for USB cables. If you're keen for some 47 Labs Stratos cables, let me know. I bought 100m for bulk discount, and can't seem to finish using it. X^D

 

[DjBobby]

Although my D50 is externally powered, whenever I connect the USB signal cable to the Macbook it turns on automatically. I was wondering is there some kind of auto-power on function which recognizes the source or is it more some voltage leaking through the usb input.

 

[carlmart]

My concern is what happens to the 5V coming through the USB cable when you use an external supply.

 

[jaxz]

Although my D50 is externally powered, whenever I connect the USB signal cable to the Macbook it turns on automatically. I was wondering is there some kind of auto-power on function which recognizes the source or is it more some voltage leaking through the usb input.

Yes, it's called 'auto mode on' at menu settings.

 

[BattousaiX26]

Although my D50 is externally powered, whenever I connect the USB signal cable to the Macbook it turns on automatically. I was wondering is there some kind of auto-power on function which recognizes the source or is it more some voltage leaking through the usb input.

This happens to me also.