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

[Marco]

I'm presuming that your pre has a volume knob on the front of it? If so, what I'm saying is that rather than level matching the cdp with the volume knob at the same place, take the lower input from the pi and make up for it by turning the volume knob on the pre up until the levels in the room are the same as with the cdp.

Obviously the output level of the Pi is driving the input level of the pre, there will be an optimum value for this - too low and the pre has to do too much work, too high and the pre inputs will start to distort. Given that an amount of this is about satisfying an audiophile tendency, I'm thinking that having the pi set up to do no digital gain changing but pushing the analogue output level and then making up the difference with the expensive gain in your pre-amp would be preferable than 'messing with your bits' (via the PCM control).

Unfortunately this will make comparing a little harder as it will be difficult to match the sound level in the room and most research seems to show that even with tiny differences in volume listeners will prefer the louder source.

Ok, I get what you mean now. I will experiment a little further with it.

However, in my system, there's quite a discrepancy between the output of my Sony DAC and that of the IQ Audio, equating to five clicks on the volume knob of my preamp [I have a 100k DACT stepped attenuator on the Croft - not sure of the db difference between each click, but there are 23 available positions], if the PCM level is set at 86 (with playback in Alsamixer at full), and consequently it makes the Pi/DAC sound somewhat 'soft' and anaemic in comparison.

Level-matching the Pi/DAC with the Sony, by setting the PCM level to 96, gives the former the required 'boost', in order for it to sound as 'big'/ballsy (whatever word you wish to describe it) as my Sony CDP/DAC, when playing CDs. What you're suggesting would probably work if the output/loudness discrepancy between the two sources in question wasn't as large.

Do you see where I'm coming from?

Marco.

[AlanS]

Hi Marc,



Yes, I've tried it that way, but it doesn't seem to be as good as leaving the playback boost off and using a higher PCM setting.

To obtain the same output from the Pi/IQ-Audio DAC, as I get from my CDP [i.e level-matched], the PCM setting needs to be 96. Any less than that, even with the playback boost on, results in a softer and less 'punchy' and wide open sound, not to mention significantly less output than my CDP provides, at the same volume setting on my preamp.

You didn't answer my point about not being able to adjust playback or playback boost in increments. With both here (in Alsamixer), it's either 'all or nothing'. Is that how it's supposed to be?



Indeed. I'll ask Gordon about that one.

Marco.

My experience of setting those level bars was that I convinced myself that the red indicated distortion and I adjusted so no red showed. Level dropped but it sounded sweeter than loads of red showing. Made sense too RED danger, just below on the edge of danger.

Over and out

[Marco]

Yes. I get the same.

The alsamixer settings are a tweakfest. You're not going to break anything, so have a play and use what best suits your ears.

Ok, that's good to know. Any idea what the 'Auto Mut' thing is supposed to do?

Marco.

[Marco]

My experience of setting those level bars was that I convinced myself that the red indicated distortion and I adjusted so no red showed. Level dropped but it sounded sweeter than loads of red showing. Made sense too RED danger, just below on the edge of danger.

The problem is, Alan, that there is no incremental adjustment available, enabling you to move those bars (other than the PCM one) to anything other than full-on. Using the 'up' arrow on either Playback or Playback Boost, simply results in setting either to maximum.

So how did you adjust them until no red showed?

Also, there's no audible distortion here, with the Playback level on full and Playback Boost off.

Marco.

[The Barbarian]

If you get this Raspberry/DAC right it should sound better than your CDP.. The past experiments with lossless files has brought me to a simular conclusion

Yeah, time to sling the HRT!



Marco.

Well naturally i will be ordering that DAC for the Rasper see what gives between the two.. Where's the best place to source this DAC btw?

[Marco]

Here, dude, but I think they're out of stock just now for a few weeks (lots of folk waiting for one): https://www.tindie.com/stores/IQaudI...n=badge_medium

Marco.

[rectorydp]

Just one thing, Mark...



I've found that adjusting both the playback and playback boost levels, using the up and down arrows on my keyboard, doesn't allow for any incremental adjustment: it's either all or nothing... The only incremental adjustment available, via using the up and down arrows on the keyboard, is with the PCM (master volume) setting.

Is that normal?

Marco.

I've not been able to drop in on this discussion for a while so I am not really up on what is going on. However, my reading of the chip spec was that these settings are either on or off so what you are seeing is to be expected. Playback is the analogue control and will either give you 1v or 2v rms max output. You should just set that to the level that works best with your preamp. The boost appears to give an additional gain of 0.8dB (according to the IQaudIO docs) and is either on or off.

[Marco]

Hi David,

Good to see you popping in again

However, my reading of the chip spec was that these settings are either on or off so what you are seeing is to be expected.

Handy to have that confirmed. Dunno then how Alan S (apparently) managed to adjust them incrementally, so that the red part of the bars didn't show... I think he was having us on!

Playback is the analogue control and will either give you 1v or 2v rms max output. You should just set that to the level that works best with your preamp.

So, in effect, off is 1v, and on is 2v RMS output (as Playback can only be either on or off)?

The boost appears to give an additional gain of 0.8dB (according to the IQaudIO docs) and is either on or off.

TBH, I can hear very little difference with that on or off... It's the adjustment of Playback that makes the significant and worthwhile difference. However, I've settled on the boost being off, and have dropped the PCM level back to 95 (from 96), which is where from now on I'll be using it.

Marco.

[Ashmore]

Hi

Very interesting thread. Forgive me if this has been covered already (I got through 30 pages before composing), but is the emerging view that the pi2+IQ dac would give an SB Touch/Caiman mk1 setup a run for its money (noting that both have longdog linear PSUs and the caiman had a full Jimmy Drips workover)?

If I were tempted to test the water presumably I could turn the Pi into a Squeezeplug and use it just like the Touch (ie stream from the vortexbox and internet using LMS over my wired network).

Would either Longdog Linear work with the pi (I am an electronics numpty)?

Simon

[Marco]

Well naturally i will be ordering that DAC for the Rasper see what gives between the two.. Where's the best place to source this DAC btw?

Btw, I forgot to say, don't let the fact that the Tindie website is priced in Dollars put you off (as I know you don't like importing stuff from abroad). The DAC is actually shipped from Glasgow (UK), just as it says:

Ships within 1 day
United Kingdom

Marco.

P.S Sorry, Simon, can't help you with that one. However, I'm sure that someone who can will soon.