Squeezebox sound quality vs CD, and Panny XR55 info

[bikeman]

So tell me how the speakers convert digital to analog.....

Ah, magic?

David

[Jonnyozero3]

So tell me how the speakers convert digital to analog.....

Dave's crossovers must be more capable than I even imagined!

[Grayson73]

This is getting over my head, so I'll just post some links and some quotes from what I've read.

There is no DAC in a Digital Amp:
http://www.puredigitalaudio.org/digi...rs/index.shtml

Here's a nice explanation of the equibit technology used in the Panasonic (and Tact, etc.):
http://www.diyaudio.com/forums/showt...3877#post83877

More quotes:

"Of course, a PWM power amp is essentially a DAC that delivers a high current output sufficient to drive speakers, so in a strict sense there is still a DAC involved, as there ultimately must be if you want to get music out of the system"

"I wouldn't want to call it a PWM DAC, it's more like a filter than a traditional DAC."

"These units (unless *I*'ve gotten really befuddled along the way) use an
Equibit-chip-based power DAC -- which is to say that this PWM DAC is
(essentially) connected directly to the speakers, and powers them. This
architecture is implemented at a low price point by Panasonic, and at a
higher one by TacT.

The reason one would choose to buy one of these Pannys is precisely for
the sound quality of the D/A-converting output stage (or its potential
sound quality, after a few parts-quality improvements); at their best,
this technology can provide a spooky level of immediacy, directness,
purity, or however else you wish to describe it. It'll only be showing
its full potential driven digitally, with internal filters and A/D
conversions switched out.

To drive one via an analog input would not accomplish the bypassing of
the power DAC; it'd just lay the sonic signature of the DAC you added
*and* the signature of the Panny's internal A/D converter (since the
output stage needs a digital signal) atop that of the Equibit
implementation."

[Grayson73]

I am still blown away by TV and movie performance, but am not too impressed so far with CD music. It doesn't sound as full as I'd like even though it is very detailed. Seems like I'm missing good midrange/upper bass and highs are too bright.

I was testing with the Kelly Clarkson Breakaway CD and Clay Aiken's CD.

I have 340SEs across the front with SVS 25-31CS sub, Panasonic SA-XR50 (100hz crossover), and Sony DVP-NS75H.

Is the problem with:
1. The CD capabilities of the DVP-NS75H
2. The 100hz crossover and/or the Panasonic SA-XR50
3. CD quality of the CDs I tested
4. Something else

I tried stereo with sub, stereo full range without sub, and DTS Neo:6. Adjusting the bass helped a little bit, but I can only do that in stereo mode.

I think I'll eventually try the SA-XR57 to see if the combination of dual amping, 80hz crossover, and upgraded electronics (I assume) improve the sound quality.

Am I expecting too much out of the speakers?

I listened to the same CDs again and they sounded better to me. Could be speaker break-in or my ears adjusting to it.

I still like the sound of the 340s with 2-channel full range. 2-channel plus sub crossed over at 100hz didn't sound as good in the midrange to me, but did provide more bass for bass heavy songs.

When the price drops to around $250 for the XR57, I'll pick one up for the 80hz crossover which will definitely improve things. I would guess that 60hz would probably be good and maybe even better.

[cyberbri]

I listened to the same CDs again and they sounded better to me. Could be speaker break-in or my ears adjusting to it.

I still like the sound of the 340s with 2-channel full range. 2-channel plus sub crossed over at 100hz didn't sound as good in the midrange to me, but did provide more bass for bass heavy songs.

When the price drops to around $250 for the XR57, I'll pick one up for the 80hz crossover which will definitely improve things. I would guess that 60hz would probably be good and maybe even better.

How well do you have the sub integrated? Have you checked for any cancellation due to phase? That could be sucking out SPL in certain frequencies.

Having the sub take over the bass should actually put less stress on the receiver and speakers because they are no longer reproducing the lowest and hardest-to-drive frequencies. Properly integrated, switching over to the sub shouldn't be noticeable except for deeper bass extension. So I don't know how the "midrange" could sound different. But something definitely sounds not right.


What crossover works best also depends on the room and acoustics, and the speaker placement within the room, as much as the speakers/sub themselves. You may have to adjust the crossover to get around room/acoustic anamolies at certain frequencies, etc.

[curtis]

This is getting over my head, so I'll just post some links and some quotes from what I've read.

There is no DAC in a Digital Amp:
http://www.puredigitalaudio.org/digi...rs/index.shtml

Here's a nice explanation of the equibit technology used in the Panasonic (and Tact, etc.):
http://www.diyaudio.com/forums/showt...3877#post83877

More quotes:

"Of course, a PWM power amp is essentially a DAC that delivers a high current output sufficient to drive speakers, so in a strict sense there is still a DAC involved, as there ultimately must be if you want to get music out of the system"

"I wouldn't want to call it a PWM DAC, it's more like a filter than a traditional DAC."

"These units (unless *I*'ve gotten really befuddled along the way) use an
Equibit-chip-based power DAC -- which is to say that this PWM DAC is
(essentially) connected directly to the speakers, and powers them. This
architecture is implemented at a low price point by Panasonic, and at a
higher one by TacT.

The reason one would choose to buy one of these Pannys is precisely for
the sound quality of the D/A-converting output stage (or its potential
sound quality, after a few parts-quality improvements); at their best,
this technology can provide a spooky level of immediacy, directness,
purity, or however else you wish to describe it. It'll only be showing
its full potential driven digitally, with internal filters and A/D
conversions switched out.

To drive one via an analog input would not accomplish the bypassing of
the power DAC; it'd just lay the sonic signature of the DAC you added
*and* the signature of the Panny's internal A/D converter (since the
output stage needs a digital signal) atop that of the Equibit
implementation."

It says right there that there is a digital to analog conversion. The question is now if that conversion is better than that of the any number of "traditional" DACs that exist.

[Grayson73]

How well do you have the sub integrated? Have you checked for any cancellation due to phase? That could be sucking out SPL in certain frequencies.

The phase is currently set to 0 and I didn't mess with it. The way to figure out cancellation would be to use DVE lower frequency sweep with SPL meter?

[cyberbri]

The phase is currently set to 0 and I didn't mess with it. The way to figure out cancellation would be to use DVE lower frequency sweep with SPL meter?

You can use sweeps to see if you get a dip in response with either setting. Or, if there are special phase tones with bass noise around/above/below the crossover point, the setting that is more in phase will give you more SPL than out of phase.

For example, measuring with an SPL meter and 1/3 octave tones, testing my VTF-3 at a certain spot in my room, you can see in the attached image how much bass I lost when the phase setting was at 0, putting it out of phase with the main speakers. That's a 15-20dB drop from about 75-140Hz or so.

This is the second sub in the second room I have tested where, when placed at the front right of the room, along the right wall in front of the right speaker, a 180-deg phase setting has produced the best results for me.

[Grayson73]

Sorry for going off topic on this thread.

I have Ascend 340 SEs across the front and SVS 25-31CS sub. Speakers are set to 'small' and crossover at 100hz.

I was running the 6 channel bass frequency sweep in DVE (goes up to 150hz).

Using 85db as a reference, phase 0 varied between 76-84 and dropped off at around 89hz.

Phase 90 varied between 76-84 and dropped off at around 96hz.

Phase 180 varied between 76-84 and dropped off at around 98hz.

Does this mean that I should set phase at 180? Doesn't this mean that polarity is switched on my sub? Setting phase at 0 and swapping the positive and negative on my sub would have the same result, right?

Also, doesn't this mean that the sub is going in during bass hits rather than pushing out? To me, that would mean that the 'thumps' won't be as loud and defined.

Am I supposed to test a different way?

[cyberbri]

Sorry for going off topic on this thread.

I have Ascend 340 SEs across the front and SVS 25-31CS sub. Speakers are set to 'small' and crossover at 100hz.

I was running the 6 channel bass frequency sweep in DVE (goes up to 150hz).

Using 85db as a reference, phase 0 varied between 76-89 and dropped off at around 89hz.

Phase 90 varied between 76-89 and dropped off at around 96hz.

Phase 180 varied between 76-89 and dropped off at around 98hz.

Does this mean that I should set phase at 180? Doesn't this mean that polarity is switched on my sub? Setting phase at 0 and swapping the positive and negative on my sub would have the same result, right?

Also, doesn't this mean that the sub is going in during bass hits rather than pushing out? To me, that would mean that the 'thumps' won't be as loud and defined.

Am I supposed to test a different way?

Can you explain your test procedure again? What tones, how you measured, speakers on/off, what results you got, etc.? What do you mean "dropped off"? No output above that?

And are you running the sub off of speaker-level inputs, then back out to the mains? Or are you running off the LFE/sub cable?

The Phase issue comes into play with room acoustics, and the timing the bass reaches the listening position from different bass drivers (speakers/sub). If they reach the LP out of phase, you get cancellation at various frequencies.