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

[Marco]

Yup, as that's what I'm keen to try (at its best), as I already know how good things sound without the preamp, using Volumio.

If you do it in the form of a simple step-by-step guide, in terms of 'go to X, click on Y, and do Z', so that I'm simply following your instructions 'parrot fashion', with no need to 'decipher' tech-speak, then that would be much appreciated!

Marco.

[Marco]

Hi David,

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.

Since you're obviously knowledgeable in these matters and reasonably local (I'm in Wrexham), if you were willing, at your convenience, to pop round here and have a look at things for me (as well as have a music sesh), I'd be more than willing to pay your fuel costs and provide a hot meal and drinks!

I don't even mind coming to collect you, or meeting you halfway at a train station if that suits better

Marco.

[r100]

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?

I am running my Pi+DAC combo with a standard 5v/2a power pack (smaller than the one in your link). I guess the important thing is that it can charge/discharge at the same time so that the battery is always 100% charged. Apparently, if the battery is lower than 100% it can affect SQ.

IMG_5224.jpg

[r100]

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.

Thank's for the info. That was my (undocumented) feeling as well

[lovejoy]

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?

I have, and with a battery very much like that one. It works very well and is a step up sonically from any cheap 5V wall-wart that delivers upwards of 1A. But I've had some more success with some better quality PSUs that I've found lying around. Currently I'm using the one out of a chunky old external CD-ROM drive caddy that I no longer use (just not using the 12V output) and that is a step up from the Anker battery in terms of sounding more solid and punchy. I'm aiming for a good linear supply eventually but a few other things to play with before then ;-).

[Marco]

Roops,

Have you got no idea then why, when using my preamp, I'm getting proper sound levels through, when the Volume Control Mixer (on Volumio) is set at 'Hardware', but not when it's disabled?

I've heard my preamp, with the Pi, on a number of occasions with 'Hardware' enabled, and it sounds great, but not as good as it does with the preamp out of the equation, so if I can obtain the same proper sound levels by disabling 'Hardware', and using my preamp, then according to you, that should sound best of all.

I'm still a little scpetical, though, even if I get that to work, that it'll provide a significant enough sonic improvement to change my mind on my using my preamp in this particular application. From earlier on the thread, where it was explained (I forget now by whom), it seems that there are valid design reasons why Pi/DAC sounds best used 'au naturel', as it were

Marco.

[r100]

I'm aiming for a good linear supply eventually but a few other things to play with before then ;-).

there are some nice looking ones on the eBay, maybe like this one ?
http://www.ebay.com/itm/Hifi-linear-...item20f80f7928

[r100]

Roops,

Have you got no idea then why, when using my preamp, I'm getting proper sound levels through, when the Volume Control Mixer (on Volumio) is set at 'Hardware', but not when it's disabled?

I've heard my preamp, with the Pi, on a number of occasions with 'Hardware' enabled, and it sounds great, but not as good as it does with the preamp out of the equation, so if I can obtain the same proper sound levels by disabling 'Hardware', and using my preamp, then according to you, that should sound best of all.

I'm still a little scpetical, though, even if I get that to work, that it'll provide a significant enough sonic improvement to change my mind on my using my preamp in this particular application. From earlier on the thread, where it was explained (I forget now by whom), it seems that there are valid design reasons why Pi/DAC sounds best used 'au naturel', as it were

Marco.

Yes, it seems that is the way the IQ DAC sounds best. Mine (Sabre DAC implementation) sounds best when Mac / Spotify volumes are a 100% and I use the Volume knob on my amp or just a passive LDR or ALPS based pre. I may just get an IQ DAC for the fun of it to be able to compare..

[WAD62]

I have, and with a battery very much like that one. It works very well and is a step up sonically from any cheap 5V wall-wart that delivers upwards of 1A. But I've had some more success with some better quality PSUs that I've found lying around. Currently I'm using the one out of a chunky old external CD-ROM drive caddy that I no longer use (just not using the 12V output) and that is a step up from the Anker battery in terms of sounding more solid and punchy. I'm aiming for a good linear supply eventually but a few other things to play with before then ;-).

Cheers Rich, and Rupert

I have the Anker to hand, so I should be fine...

[Marco]

Yes, it seems that is the way the IQ DAC sounds best. Mine (Sabre DAC implementation) sounds best when Mac / Spotify volumes are a 100% and I use the Volume knob on my amp or just a passive LDR or ALPS based pre. I may just get an IQ DAC for the fun of it to be able to compare..

Cool... It'll be interesting to know what you think of the IQ-Audio DAC when you compare it with what you have

So do you know why I'm getting no volume (with my preamp in the equation) when I disable the 'Hardware' setting in Volumio? Is it because what you were telling me to do before doesn't work with the IQ-Audio DAC?

Marco.