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"No-Dac" and "No-USB"


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Ive been playing around with a couple of different ways that differ from the conventional CA approach.

The first is a no dac system that dispense with dac entirely and plays dsd as an analog signal, so all that is needed is appropriate usb-i2s converter that can output dsd. Either native dsd or pcm converted to dsd on a computer is sent to usb-i2s device The output is passed through low pass filter as an analog dsd signal . That's it, the signal is passed straight to high gain preamp and it sounds very good.

The downside is the largish computer power needed for the dsd conversion and tendency for pops between tracks. Im using an i5/i7 and mute board to get around these problems .

Usb boards used are the Amanero and the JLSounds, the JL superior as it has separate power supply regs for usb and clock supplies. And it runs on linux which I've come to believe is superior to windows for audio.

For the JL sounds I'm using Daphile for pcm-dsd conversion and JRiver forthe Amanero.

Cost is no more than $200 max, and sound would easily embarrass devices costing 10 times that.

Other method is no usb operation with direct i2s connection into suitable i2s dac.

The cheap and nasty raspberry and beaglebone mini computer boards have direct non usb i2s outputs, but their audio outputs are horrible and barely hi-fi . The trick is to bypass their inbuilt clocks using a fifo buffer. This transforms the nasty jitter ridden original digital signal into a near perfect jitter less signal, which in my case ,is then passed through isolaters, fancy Chyrstek double clocks, and a device which allows 24 bit/384Khz operation of the old faithful TDA1541 dac chip in data sim mode, turning it into a hitech R2R dac, and we all know a good r2r dac is still the closest way to get to the music, damn all those delta sigma devices. ( I've heard good 9018's but only at stupid prices)

Battery power for the rasberry, high quality regs for all the digital boards.

Even with usb operation this dac is very good, but going to non usb it really is something else. Everyone who hears it comments on how organic and musical it is with 3D imaging that makes the speakers sound like they've been replaced by the band or singers, instruments have their own place and starkly rendered , but in that organic beautiful tone that is not at all reminiscent of digital, yet it also doesnt sound like "vinyl" or analog, it's just "right".

As im using a raspberry pi2+ the os is linux/moode player . In comparison to the heavy lifting of the pcm-dsd conversion this system's computing lopes along at 10% cpu.

But this system costs a lot more to build than the no dac method and is quite complex in comparison, however they somewhat have the same sound signature, a lack of digital weariness, and ease of listening.

I prefer the no usb system over the no dac system, but its early days and I believe were in for a bit of a shake up in digital design in the coming years.

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Take a DSD stream, low pass filter it and amplify it.... What you get is music. The PS Audio DS dac is built on this premise.

Wow really? So DSD was an analog signal? Didn't know about that.

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DSD isn't analog, it's still digital... It just closely resembles the analog signal it encodes.

 

Sort of. First of all, DSD is just a marketing/branding term for a commercial format/version of PWM.  PWM does not require conversion to a discrete numeric representation like PCM digital audio - there are no "ones and zeros" required in encoding, in the sense that we usually think of it.  The signal is essentially an ANALOG representation of the music signal. So no decimation filter on reconstruction to analog. You can send a PWM signal directly over analog cables to an amp and you will get music/sound on the other end. But the result will be noisey. So you need a simple filter to get rid of the noise. 

 

One can make a good argument that PWM is closer to analog than it is to digital. 

 

See: http://www.psaudio.com/pauls-posts/analog-coding/ and 

 

http://www.psaudio.com/pauls-posts/class-dsd/ 

 

for a simple explanation. 

Edited by firedog
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I have not trying it myself but seems recent refinement has improved the quantisation noise. 

"recent refinement" - hardly , its just a low pass filter consisting of a cap and resistor, and another cap to block DC.  Sometimes the simplest solution is the best solution.

Combining the "no- dac" and the "no-usb" would simplify it even more , and could be even better.

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Heard Mick's no-dac approach in house recently, sounded very good. Main attribute was a 3D ball of imaging that had excellent front to back depth, clarity also first rate.

The device looked easy to put together, a $100 Amanero USB board taking the computer data (music stream) and a simple filter consisting of a couple of resistors and favourite film capacitor with RCA output. The thing didn't even need a dedicated power supply, drawing 5v for the Amanero from the PC USB line.

Steve.

Edited by Steve M
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Heard Mick's no-dac approach in house recently, sounded very good. Main attribute was a 3D ball of imaging that had excellent front to back depth, clarity also first rate.

The device looked easy to put together, a $100 Amanero USB board taking the computer data (music stream) and a simple filter consisting of a couple of resistors and favourite film capacitor with RCA output. The thing didn't even need a dedicated power supply, drawing 5v for the Amanero from the PC USB line.

Steve.

 

The JLSounds board is much better, it requires two separate power supply regulators, but has  better clock and implementation than the Amanero, imo.  But the Amanero is very easy to get going. 

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Hi @@statman, thanks for your contributions!

 

I would like to try this: do I just buy an Amanero board? What else do I need? Could you perhaps post a picture of your set-up?

 Yeah I can do that, but not till weekend, I'll post a guide. Bear in mind you need a gutsy computer to do the pcm-dsd conversion, and with the simple Amanero set up, you will get popping noises between tracks, its not too bad, wont do any damage but it freaks out the anal audiophiles, and god knows there's a gazzillion of them. 

The JLSounds board sounds a lot better imo , but it needs mains power and transformers, and that can kill you if you are a beginner diyer.

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Yeah I can do that, but not till weekend, I'll post a guide. Bear in mind you need a gutsy computer to do the pcm-dsd conversion, and with the simple Amanero set up, you will get popping noises between tracks, its not too bad, wont do any damage but it freaks out the anal audiophiles, and god knows there's a gazzillion of them.

The JLSounds board sounds a lot better imo , but it needs mains power and transformers, and that can kill you if you are a beginner diyer.

Thanks! I can live with pops. I am not experienced with DIY so sounds like Amanero is the go for me.

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post-112248-0-93292400-1454135172_thumb.

Ok, to build the simplest version of the no-dac you need an Amanero board, a pair of RCA connectors, wire, 2x 3K3 (3300) ohm resistors and 2x 1000pF (0.001uF) capacitors. If your preamp is cap coupled you dont need a set of DC blocking caps, but if your not sure put them in. The value will depend on the input impedance of your preamp, a tube pre with input impedance around 100K will be fine with 0.47- 1.0uF, solid state go up to 10uF.  If your not sure use 10uF. 0.47uF Auricaps shown here. 

I used 2200pf (0.0022uF) caps for the filter because they were already on tagstrip, but "correct" value is 1000pf, 2200pf will give a bit more attenuation of high freq noise. 

The gurus will tell you you need to use exotic caps, but the performance of the no dac will exceed the relative merits of different types of caps, use what you like. Even electros for blocking cap are ok, I really like the ELNA Silmics, but hard to get. If you use electros + terminal to junction.

Use pins 3 and 5 of the Amanero for the right and left DSD outputs. Any of the ground pins for grounding. So a wire from pin 5 goes to one end of a 3K3 resistor, the other end of the resistor gets connected to the 1000pF cap, the other end of this cap gets connected to ground. The junction of 3K3 and 1000pf is the output of the left channel. This gets connected to the blocking cap, and the other end connected to RCA hot connection, the middle pin.  The earth tab of RCA of course gets connected to earth. 

post-112248-0-86240200-1454135218_thumb. 

post-112248-0-21107000-1454135279_thumb.

Same for pin 3 which becomes right channel. 

 

Ignore the white wires, I was using Amanero for something else. And the pink, yellow, green wires on output.

 

 

For pcm-dsd conversion the easiest way is to use JRIver. First download and install the drivers for Amanero from the website. Then on JRiver- Tools- Options- Audio Device select as shown on pix.

You'll need to have the device attached for this to show up.

 

post-112248-0-52970100-1454135345_thumb.

 

 To encode pcm-dsd : Tools-Options-DSP Studio, select 2x DSD DoP . If you have native DSD files you can select Native , but for playing ordinary pcm files use DoP.

 

post-112248-0-86678900-1454135409_thumb.

 

And finally click mouse on Audio Path when playing and it will show DSD output 5.6Mz in this case. Keep the volume down initially to ensure pop between tracks is not an issue.

 

 

post-112248-0-75643500-1454135889_thumb.

 

This will be interesting to most of you brought up on opamps in output stages of dacs, here we are eliminating the opamps and the dac! 

The simplicity and lack of phase rotation gives a big sound, good imaging and soundstaging. 

Its a bit raw, but going to the more sophisticated JLSounds board makes it more organic and natural sounding. And Linux can be used which I prefer over Windows. And a mute board can get rid of pops.

I still prefer the no-usb approach which is even more natural sounding, maybe there's still a hint of digital with the no-dac , not so with the no-usb.

Some smart digital guy needs to figure out how to combine no-usb and no-dac!

 

 

 

 

 

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Wow well done statman! Amazing so simple. I will definitely give this a go next week when & if I get ten minutes free. The Amanero board has a muting out pin so you could probably use this to drive a simple muting circuit. I'll see if I can come up with something simple if you like. Might even post some scope shots too & see what a 20k sign wave looks like.

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Wow well done statman! Amazing so simple. I will definitely give this a go next week when & if I get ten minutes free. The Amanero board has a muting out pin so you could probably use this to drive a simple muting circuit. I'll see if I can come up with something simple if you like. Might even post some scope shots too & see what a 20k sign wave looks like.

A 20Khz sine wave would probably ruin all the fun. If you must measure it a 1KHz square wave would be a more realistic reference , imo.

BTW I forgot to mention you need a high gain preamp, or sensitive amps, the no dac doesn't put out the standard dac 2.0V. 

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OK 1KHz square wave it is. I'm not paranoid about measurement but it is just nice to known what is going out to the speakers. It might sound better if I run it into my usual composite output buffer which I could incorporate the filtering as well. I getting the feeling that this is going to sound pretty dam good so maybe It would be worth while doing a DIY board/kit. Say a small PCB with a low noise PSU for the Amanero plus buffer/filter/muting output section. What do you think? How much better is the JLsounds board? I see it has galvanic isolation plus reclocking.

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OK 1KHz square wave it is. I'm not paranoid about measurement but it is just nice to known what is going out to the speakers. It might sound better if I run it into my usual composite output buffer which I could incorporate the filtering as well. I getting the feeling that this is going to sound pretty dam good so maybe It would be worth while doing a DIY board/kit. Say a small PCB with a low noise PSU for the Amanero plus buffer/filter/muting output section. What do you think? How much better is the JLsounds board? I see it has galvanic isolation plus reclocking.

Yes please :thumb:

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OK 1KHz square wave it is. I'm not paranoid about measurement but it is just nice to known what is going out to the speakers. It might sound better if I run it into my usual composite output buffer which I could incorporate the filtering as well. I getting the feeling that this is going to sound pretty dam good so maybe It would be worth while doing a DIY board/kit. Say a small PCB with a low noise PSU for the Amanero plus buffer/filter/muting output section. What do you think? How much better is the JLsounds board? I see it has galvanic isolation plus reclocking.

Well the beauty of the Amanero is that it is easy for new diy'ers, with no mains power supply. The JLSounds is  better, with  better clocks etc, but it needs two independent power supplies/regulators, which means transformers and mains, and we dont want to kill anyone.  If you want to do a pcb go for it, there's usually little demand for this type of thing, but as long as it doesn't end up costing you......

I must try the Amanero with Linux, had it going with Daphile, but didn't give it a decent listen, might be worthwhile as the JLsounds is running Linux.

Gordon do you know of any other program besides JRiver, Daphile, Foobar and HQPlayer that does pcm-dsd conversion? (but no mac please) 

Edited by statman
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