Phase Alignment - WOW, WOW, WOW!

[manisandher]

I didn't want to share my thoughts on PA until I had 0.9z-7 installed in my main system (in sig), and I wasn't going to do this with the beta release. But I've now installed the official release in my main system.

I thought I had one of the most 'musical' systems I'd ever heard - the Sauermann amps are special, the Quad speakers are legendary and the NOS1... well this is probably the most accurate DAC in the world. BUT Peter is right - even with these components, I now know I've been listening to distortion all this time. This was obvious the first second I listened to PA. I don't wear contact lenses or spectacles but I can imagine PA is like putting a pair on when you have bad eye sight but didn't even know about it. It's a revelation.

Congratulations Peter, and thank you so, so much. I second your Nobel Prize.

(Incidentally, I measured the DC offset at my speaker terminals without/with PA. The offset is around 12mV on each channel without. When PA is engaged, this jumps momentarily to ~150mV (accompanied by a small tick through the speakers) and then falls back down to ~12mV once music starts coming out of the speakers.)

Mani.

[boleary]

Hey Mani, did you try SFS @ 2 and PA Strength at 1? This sent the SQ here even further into the stratosphere. In fact, I think that changing SFS to anything other than 2 degrades the sound--perhaps the SFS issue is now a non issue!

[manisandher]

Hmm... will take a good listen to it later this evening.

Mani.

[BertD]

Hmm... will take a good listen to it later this evening.

I just checked with my amps (without DC-protection) and it is scary what I see at the output terminals.

Just one click set for the phase alignment and already I see peaks appearing of 2V at the speaker terminals with less than 180mV or so at the input.

My speakers are DC-protected (passive crossover) and so is my active crossover for the bass so no harm can be done there but I am sure that this DC component will saturate the amps pretty quickly.

I will need to get a capacitor first to block DC before I am going to test further...

Bert

[manisandher]

Bert, on my main system (Sauermann amps) I'm measuring ~15mV at the speaker terminals without PA. With PA it goes to ~150mV, but only momentarily, before going back down to ~15mV once the music starts.

When you talk about 180mV, surely this isn't at the output of the NOS1?

I'm asssuming my gainclones would have identical DC offsets to yours, no? So no PA with these until you get them 'upgraded', right?

Mani.

[Scroobius]

Bert - I was seeing 11 volts output on my amps at -22db volume in XX  - I am waiting for my DC blocking capacitors to arrive and hoping that they do not affect sound quality too much so that I can enjoy the benefits of PA.

Paul

[BertD]

When you talk about 180mV, surely this isn't at the output of the NOS1?

Yes, the output of the NOS1 (you can see that on the internal meters...). But I have noticed also way above the limit they measure...meaning more than 1V!?

Is that good for the DAC's output stage?

What would do that at the output of the amps... brrrr.

In the meantime I have installed the capacitors though and will let them burn in for a while and continue from there.

I'm asssuming my gainclones would have identical DC offsets to yours, no? So no PA with these until you get them 'upgraded', right?

Yep, same thing but no need for an "upgrade". Just add a capacitor in series with the input and DC will be blocked.

You'll need minimal 15uF though and for a high grade one this will cost some and might not even fit inside! But you can use a good quality 15uF and 1u5 by-pass with real good quality.

Bert

[BertD]

Bert - I was seeing 11 volts output on my amps at -22db volume in XX  - I am waiting for my DC blocking capacitors to arrive and hoping that they do not affect sound quality too much so that I can enjoy the benefits of PA.

That IS a lot... I did not check my volume settings with the readings but I will have to play on any volume so it should be safe always.

Bert

[manisandher]

When you talk about 180mV, surely this isn't at the output of the NOS1?

Yes, the output of the NOS1 (you can see that on the internal meters...). But I have noticed also way above the limit they measure...meaning more than 1V!?

Is that good for the DAC's output stage?

Hey Bert, this is way too high. My two NOS1s read between 0.5mV and 7mV on their respective channels.

???

Mani.

[BertD]

Hey Mani, did you try SFS @ 2 and PA Strength at 1?

I did try SFS @ 2 and that did not work. The player complaint with an error telling me that the figure 2 is too small for unattended playback...

Bert

[BertD]

Hey Bert, this is way too high. My two NOS1s read between 0.5mV and 7mV on their respective channels.

Tell me about it! I am sure it is related to the volume setting but perhaps also because of the DC blocker? Now the DAC can't have its DC floating anymore...

Although, I also have seen tracks play with 150mV NOS1 output) without changing the volume. Perhaps Volume Normalisation is playing tricks here...

Time will tell.

Bert

[BertD]

Hey Bert, this is way too high. My two NOS1s read between 0.5mV and 7mV on their respective channels.

Are you sure that you actually have engaged Phase Alignment? You need to do this in the settings menu and then choose strength or +/- on the player itself.

Bert

[boleary]

Hey Mani, did you try SFS @ 2 and PA Strength at 1?

I did try SFS @ 2 and that did not work. The player complaint with an error telling me that the figure 2 is too small for unattended playback...

Bert

Maybe you need to set Q1 to fourteen. See below from this note from Peter: http://www.phasure.com/index.php?topic=2093.msg21474#msg21474

Addendum :
A month or so after this was written originally, it was found that a very low Split File Size (SFS) solves about all of the theoretical problems we can run into. So, an SFS of 2 allows for a Device Buffer Size of 4096, a Q1 of 14 and a Q1Factor of 1, which gives the net result of a fairly short buffer size while Phase Alignment works beautifully; in this setting the repeat of the last buffer (by sort of mechanical organization) is very short but also very long in frequence. For net result it will even be difficult to detect it (think like 50ms worth of audio repeating 10 times now).
This is important, because it will allow everybody to use it, while at first it was thought that only the "huge buffer sizes" would allow for it, that sure not being able to dial in for all DACs.

And:

Addendum :
Referring to beforementioned SFS setting of 2 which works "the best", it has been found also that applying a Strength of 1 sure can improve. Again it is difficult, because it first required the general nature of sound (or quality of it) "depicted" by the SFS=2 setting before it started to work out. So, despite the warnings above, an SFS of 2 with further settings as described under the earlier Addendum, seems quite safe in order to try a Strength of 1. Sadly, again later it was found that with this Strength of 1 and an SFS of 60, sound seems to get as analogue as can be, hence totally different and seemlingly way better again. Sadly, because with the further settings the same, you won't be free of small ticks at stopping or Volume Change etc. Still harmless, but not free of anomalies (which SFS = 2 seems to provide).

[boleary]

One more thought, my last post was to be understood in the context of using PA; if you are not then I'm not sure of the benifit of the smaller SFS.

[manisandher]

Are you sure that you actually have engaged Phase Alignment?

Yes, PA definitely engaged. But I was just being an idiot - I quoted the DC offset at idle, and not when playing music. With PA engaged, the meters go off scale when music is playing.

On a side note: Bert, my Quads have transformers at their inputs, so aren't bothered by the amp's DC output. Would the gainclones care if they outputted >1V DC? I mean, in my case, with my Quads, do I really need an input capacitor on my amps?

Mani.