'Analog Dinosaur' succumbs to the joys of FBA : enter Raspberry Pi 2/IQ-Audio DAC+!!

[Marco]

That's why I linked the manual, it's all explained in plain terms there for you ;-)

Lol... You may think the information there is explained in 'plain terms', but I'm afraid it's mostly a foreign language to me... When it comes to computers, with me, think along the terms of a 5-year old learning English!!

To do any of the technical stuff outlined in that manual, I would need someone here to explain what it all means first, before I could implement it. Dave (jollyfix) said it best earlier:

...for me its like some one saying " hey fit this to your car, you will get 100 more mile per gallon, it also has auto reverse etc. only thing is to use it you need to strip down gear box .add a turbo move some pipes etc". All fine if you have a bit of mechanical knowledge.

...or in this case, computer terminology knowledge.

Anyway, I do appreciate your help

Marco.

[Rothchild]

Lol... You may think the information there is explained in 'plain terms', but I'm afraid it's mostly a foreign language to me... When it comes to computers, with me, think along the terms of a 5-year old learning English!!

To do any of the technical stuff outlined in that manual, I would need someone here to explain what it all means first, before I could implement it.

Marco.

I'll try to do you an ELI5 (explain it like I'm 5) version later. If you could clarify for me which 'hardware control' you are using on the DAC at the moment (I've been through most of the thread but it's long and diverse!) that will help me understand where you're up to and what you need to do to get the perfect gain structure through the Pi and on in to the rest of your chain.

[lovejoy]

Top stuff Rich!

I can thoroughly recommend the IQ case, very well designed, and looks the business, my earlier photo doesn't do it justice

Mind you give the build instructions a read first...http://www.iqaudio.com/downloads/IQaudIO.pdf

It'll save time in the end, it's a question of getting the right spacers onto the main Pi board first time...

Top tip! One side of the case panels is protected by sticky back plastic...and is not 'unprinted' as some idiot might complain...err sorry about that Gordon

Apparently it's a common mistake...I think he was just being polite

P.S. I'm still waiting my HDMI to DVI adaptor to arrive (hopefully today) before I light the blue touch paper...

Thanks for the tips. That case does look ace! A case is a must and it's about time I got a good one. I bodged one when I got the HiFiBerry Digi but it's a bit Heath Robinson.

Getting all excited now ;-)

I used SqueezeLite for a while when I was making the transition from my SBT to using the Pi for streaming duties - I was about to mention how you don't really need to use the HDMI output of the Pi at all for configuration and you can do it all over a web browser, but then I remembered that for the initial configuration of SqueezeLite it's not so easy as I don't think SSH is running by default and you have to enable it first (which is a little bit of an annoyance). I would say though that if you can get away from using the old Logitech way of serving up your music, Volumio definitely sounds better, or at least it does in my system - and then you can configure the whole thing via a web browser without the need for connecting a monitor directly to the Pi.

[Marco]

Hi Marc,

Okies... First of all, in terms of the DAC, I'm using the IQ-Audio Pi-DAC+, and controlling it and the Pi 2 (model B) through the Volumio web interface, on a Macbook Pro. This is the section in Volumio (as supplied earlier by Rupert), I'm referring to, in terms of 'Hardware':

Attachment 14277

What we were trying to do (aside from what you're going to try and explain) was disable the Hardware setting, so that apparently I'd get best sound quality through my Croft preamp, rather than how I'm currently using things, with no preamp, and the Pi plugged directly into my power amp, using Volumio to adjust listening levels.

I did as Rupert suggested, by disabling the above 'Hardware' setting, applying it, and noticed that in doing so it automatically set the playback levels on Volumio to 100%.

I then increased the volume on my Mac to 100%, connected the Pi to my preamp (and preamp to power amp), selected a track from my stored music library, pressed 'Play', on Volumio, then turned the volume knob up on the preamp, and heard.... NOTHING...

I then increased the volume to nearly full on my preamp, and heard the music that should've been playing sounding like a distant transistor radio! To test that there were no problems elsewhere, I simply disconnected the interconnects from the back of the Pi and plugged them into my CDP, hit play, and got BEAUTIFUL SOUNDING MUSIC, as indeed should've happened before with the Pi.

What's going on there, however, I've no idea

Marco.

[WAD62]

I used SqueezeLite for a while when I was making the transition from my SBT to using the Pi for streaming duties - I was about to mention how you don't really need to use the HDMI output of the Pi at all for configuration and you can do it all over a web browser, but then I remembered that for the initial configuration of SqueezeLite it's not so easy as I don't think SSH is running by default and you have to enable it first (which is a little bit of an annoyance). I would say though that if you can get away from using the old Logitech way of serving up your music, Volumio definitely sounds better, or at least it does in my system - and then you can configure the whole thing via a web browser without the need for connecting a monitor directly to the Pi.

As I'm a heavy SB user (QNAP LMS server & 4 SB clients), my initial experiment is to compare the Pi 2 & Pi-DAC+, to my SBTouch and HiFimeDIY U2 combo in the Kitchen, running into a Mini-1 amp & Mission 780SEs...where the object is low cost (I bought the touch second hand for £80, and the missions for £28), and grease proof!!!

I'm going to try the new SqueezePlug NOOBS distro...

http://www.squeezeplug.eu/

...and as you say the Max2Play web interface may be all I need...assuming all is well, but I've been in IT long enough to know that sh1t happens, and I'll probably need to connect a monitor at some point, so I may as well wait, as the NOOBS distro is a one off self builder

[Marco]

Roops,

I think there is some confusion about the "hardware" word in the documentation. As far as I can see, it means there is a dedicated 32 bit chip on the IQ DAC doing volume attenuation in the digital domain. So, the "hardware" seems to refer to that chip.

Not sure what you mean by that. However, in my system, disabling the Volume Control Mixer, in Volumio, simply results in NO VOLUME, rather than better sound quality!!

But all this is irrelevant really as long as the SQ is satisfying. And I am sure you have plenty of reference points to know it is.

Indeed. However, I would still like to get to the bottom of the problem, so that I can be sure that my preamp isn't going to contribute anything positive, sonically, in this particular application.

Marco.

[rectorydp]

I think there is some confusion about the "hardware" word in the documentation. As far as I can see, it means there is a dedicated 32 bit chip on the IQ DAC doing volume attenuation in the digital domain. So, the "hardware" seems to refer to that chip.

But all this is irrelevant really as long as the SQ is satisfying. And I am sure you have plenty of reference points to know it is.

I can see the hardware volume control issue is rumbling on and I suspect my previous contribution didn't really help.
I assumed that the hardware volume control was analogue because it is referred to as a significant positive point in much of the documentation.
It seems that the TI chip does offer analogue and digital gain options. See page 62 of the TI PCM512x spec (http://www.ti.com/lit/ds/symlink/pcm5122.pdf). It looks like both options are made available to the ALSA mixer in the IQ DAC but what is referred to as the hardware volume control probably relates to the Digital Volume Control. The analogue gain control appears to only offer 2v or 1V rms output.
The digital volume control on the chip appears to offer +24db to -103dB and that matches up with what is described as the hardware volume option (with some restrictions). The spec doesn't say how the Digital Volume Control is implemented but we should assume that it works as usual and will reduce the number of bits in the signal. However, given that it is a 32bit DAC it is difficult to believe that it would be discernible.

A rotary encoder seems to be an add on option to the IQ DAC but it would appear to operate on the Digital Volume Control. There also seems to be an option for IR control.

Sorry if I caused any confusion.

[Rothchild]

Hi Marc,

Okies... First of all, in terms of the DAC, I'm using the IQ-Audio Pi-DAC+, and controlling it and the Pi 2 (model B) through the Volumio web interface, on a Macbook Pro. This is the section in Volumio (as supplied earlier by Rupert), I'm referring to, in terms of 'Hardware':

Attachment 14277

What we were trying to do (aside from what you're going to try and explain) was disable the Hardware setting, so that apparently I'd get best sound quality through my Croft preamp, rather than how I'm currently using things, with no preamp, and the Pi plugged directly into my power amp, using Volumio to adjust listening levels.

I did as Rupert suggested, by disabling the above 'Hardware' setting, applying it, and noticed that in doing so it automatically set the playback levels on Volumio to 100%.

I then increased the volume on my Mac to 100%, connected the Pi to my preamp (and preamp to power amp), selected a track from my stored music library, pressed 'Play', on Volumio, then turned the volume knob up on the preamp, and heard.... NOTHING...

I then increased the volume to nearly full on my preamp, and heard the music that should've been playing sounding like a distant transistor radio! To test that there were no problems elsewhere, I simply disconnected the interconnects from the back of the Pi and plugged them into my CDP, hit play, and got BEAUTIFUL SOUNDING MUSIC, as indeed should've happened before with the Pi.

What's going on there, however, I've no idea

Marco.

Great, I'm not as far off track as I feared I might be and this is not insurmountable!

I'll put a guide together for you later tonight / over the weekend.

Just to check, will you be happy to use the volume on your croft rather than anything on the computer? (Imo this is would be the best sonic solution).

[Rothchild]

I can see the hardware volume control issue is rumbling on and I suspect my previous contribution didn't really help.
I assumed that the hardware volume control was analogue because it is referred to as a significant positive point in much of the documentation.
It seems that the TI chip does offer analogue and digital gain options. See page 62 of the TI PCM512x spec (http://www.ti.com/lit/ds/symlink/pcm5122.pdf). It looks like both options are made available to the ALSA mixer in the IQ DAC but what is referred to as the hardware volume control probably relates to the Digital Volume Control. The analogue gain control appears to only offer 2v or 1V rms output.
The digital volume control on the chip appears to offer +24db to -103dB and that matches up with what is described as the hardware volume option (with some restrictions). The spec doesn't say how the Digital Volume Control is implemented but we should assume that it works as usual and will reduce the number of bits in the signal. However, given that it is a 32bit DAC it is difficult to believe that it would be discernible.

A rotary encoder seems to be an add on option to the IQ DAC but it would appear to operate on the Digital Volume Control. There also seems to be an option for IR control.

Sorry if I caused any confusion.

This is similar to my interpretation, in ALSAMixer 'PCM' is the digital playback level in to the d/a and 'Playback' is the voltage gain of the analogue out from the da chip (as you say, variable from 1vrms (just over normal 'line level') up to 2vrms (closer to 'pro' levels normally used in balanced studio gear)).

My guess would be that in volumio 'software' means Volumio digitally attenuates the signal before passing it to ALSA mixer (so the input to 'PCM' would be lower) 'Hardware' probably connects the volumio control to 'PCM' in ALSA mixer (so there's just one digital gain stage) and 'off' maybe just disables the 'PCM' volume control leaving just the output gain adjustable.

IMO all digital playback should be neither gained nor attenuated and the 'Playback' volume should be used to adjust the drive/'heat' of the signal in to the preamp.

[WAD62]

Has anyone tried running the Pi & DAC+ combo from a battery...?

I was thinking of one of these...

http://www.amazon.co.uk/gp/product/B...ilpage_o03_s00

...anybody with any such experience?