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androidtopp
2009-09-03, 05:37
I've noticed that Logitech isn't as detailed in their spec on the Touch as they are on the Classic. For example, the Classic spec page has details like:

High fidelity Burr-Brown™ 24-bit DAC
Two dedicated linear power regulators for DAC and line-out stages
Full 6.0Vpp line-level signals
Signal-to-noise ratio: over 100dB
Total harmonic distortion (THD+N): less than -93.5dB (0.002%)
Digital S/PDIF outputs
Optical and coax digital connections
Dedicated high-precision crystal oscillators (no PLL, no resampling)
Standard IEC-958 (S/PDIF) encoding
Optical connector: TOSLINK 660nm
Coax connector: RCA, 500mVpp into 75 ohms
Sample rates: 44.1Khz, 48Khz
Audio format: linear PCM, 16 or 24 bits per sample
Intrinsic jitter: less than 50ps (standard deviation)
Headphone output
Standard 1/8" jack also functions as an IR blaster
Minimum headphone impedance: 16 ohms
Total harmonic distortion: less than 0.03%
Left/right crosstalk attenuation: 92dB

So, given that the Touch supports 24/96 playback, this is probably a stupid question, but does anyone know how the Touch will compare? Not that I could probably tell if it was any worse, but I'm blown away by the sound of my Classic, and I'm foaming at the mouth to upgrade. I just don't want to give anything up.

Thanks!
Andrew

ASenna04
2009-09-03, 05:48
Good question. I was asking myself the same question. will the sample rates of up to 24 bits at 96 kHz add anything in the audio quality compared to the Duet receiver?

ASenna04

mswlogo
2009-09-03, 06:19
I'm little concerned that the "24/96" means it supports it through SOX and may not be native. You know those Marketing guys how they like to stretch the truth. It's great is true though. Seems to me they will not sell any more transporters if true though.

ziggyb63
2009-09-03, 06:43
According to a tread in another forum, it has the same DAC as the Transporter so should support 24/96 natively...

Kiwi
2009-09-03, 06:44
I'm little concerned that the "24/96" means it supports it through SOX and may not be native. You know those Marketing guys how they like to stretch the truth. It's great is true though. Seems to me they will not sell any more transporters if true though.

I don't share your cynical perspective that Logitech would try to pass off 24/96 support with SOX. If that were the case they would be already claiming that the Classic and SB Receiver support 24/96.

I also question whether the SB Touch will take market share from the Transporter, they seem to me to be well delineated. The Transporter has features that audiophiles are looking for e.g. balanced outputs, rack mountable, appearance.

androidtopp
2009-09-03, 06:52
If it's the same DAC as the Transporter, I will be over the moon. That's assurance enough for me that I'm not giving anything up in the new device.

rtitmuss
2009-09-03, 06:58
I'm little concerned that the "24/96" means it supports it through SOX and may not be native.

It's native. The hardware supports 44.1k/48k/88.2k/96k without re-sampling.

Richard

funkstar
2009-09-03, 07:05
If it's the same DAC as the Transporter, I will be over the moon. That's assurance enough for me that I'm not giving anything up in the new device.
I'm about 90% sure it isn't the same DAC as the transporter.

ziggyb63
2009-09-03, 07:20
I'm about 90% sure it isn't the same DAC as the transporter.

Only repeating a prior post. Nice to know it does 24/96 natively...

Apesbrain
2009-09-03, 07:27
Will the Touch pass 24/96 through its digital outs to an external DAC? I have a DAC capable of 24/96 but no such sources. This would be cool! Thanks.

seanadams
2009-09-03, 07:34
It is NOT the same DAC as transporter. If anyone posted that please go delete your posts because it will get repeated as fact as we've seen here already.

I don't have the measured specs (didn't work on this product aside from some advice on how to do s/pdif right) but hopefully Caleb or Maurice will be along at some point.

funkstar
2009-09-03, 07:38
It is NOT the same DAC as transporter.
Now I'm 100% sure it isn't the same DAC :)

Thanks Sean.

nicoleif
2009-09-03, 09:28
Will the Touch pass 24/96 through its digital outs to an external DAC? I have a DAC capable of 24/96 but no such sources. This would be cool! Thanks.

I would very much like to know this as well??

remd
2009-09-03, 09:38
The DAC is the same brand, but not the same model.
its a AKM-AK4420, and the TP is a AKM-AK4396.
(higher number doesnt mean better :)

The 24b/96khz is native on the Touch as it is on the Transporter.

nicoleif
2009-09-03, 10:07
The DAC is the same brand, but not the same model.
its a AKM-AK4420, and the TP is a AKM-AK4396.
(higher number doesnt mean better :)

The 24b/96khz is native on the Touch as it is on the Transporter.

When you write that "The 24b/96khz is native on the Touch as it is on the Transporter" does that mean that the Touch will be able to pass 24/96 through its digital outs to an external DAC?

rtitmuss
2009-09-03, 10:15
When you write that "The 24b/96khz is native on the Touch as it is on the Transporter" does that mean that the Touch will be able to pass 24/96 through its digital outs to an external DAC?

Yes.

Richard

Mnyb
2009-09-03, 10:24
Yes.

Richard

Any jitter specs for the digital output ? is it a good one :)

If is better or equal to classic aka SB3 I'm happy as my ht processors dejittering equalize all differences between the SB3 and very expensive drives.

androidtopp
2009-09-03, 10:55
So, if it's the AKM AK4420 DAC, based on these specs (http://www.asahi-kasei.co.jp/akm/en/product/ak4420/ak4420.html) it looks like we can expect slightly worse THD+N, a better SNR, and a much greater bitrate/sampling rate option set.

Again, not that I'll be able to tell. I'll just pretend like I can make out the difference.

seanadams
2009-09-03, 11:05
So, if it's the AKM AK4420 DAC, based on these specs (http://www.asahi-kasei.co.jp/akm/en/product/ak4420/ak4420.html) it looks like we can expect slightly worse THD+N, and a much greater bitrate/samling rate option set.

DAC specs don't work like that. For noise and distortion you have to measure it in the final product and it can be better or worse than the data sheet, possibly by a lot. There are countless design choices at play in determining how well it ultimately performs.

For sample rates etc, DAC chips support a broad plethora of interface speeds and formats, but usually only a subset of them are appropriate/supported for a given product.

Phil Leigh
2009-09-03, 11:07
Yes, 24/96 and 24/88.2 are output faithfully via SPDIF/toslink. Greater than this is downsampled via SOX as before.
It sounds very nice indeed.

androidtopp
2009-09-03, 11:17
DAC specs don't work like that. For noise and distortion you have to measure it in the final product and it can be better or worse than the data sheet, possibly by a lot. There are countless design choices at play in determining how well it ultimately performs.

For sample rates etc, DAC chips support a broad plethora of interface speeds and formats, but usually only a subset of them are appropriate/supported for a given product.

Granted that's the DAC in a vacuum vs. the finished Classic product. But it's all I have to go on. ;-) I'm really not too concerned here...You could make that thing out of tinfoil and bailing wire, and I'd still buy a Touch.

dwc
2009-09-03, 18:56
It is NOT the same DAC as transporter. If anyone posted that please go delete your posts because it will get repeated as fact as we've seen here already.

I don't have the measured specs (didn't work on this product aside from some advice on how to do s/pdif right) but hopefully Caleb or Maurice will be along at some point.


Well if you helped them to get the S/PDIF right, then that's great for us running our own dac's (and digital Panasonic head units).

Do you have any info on the comparitive jitter of optical vs. RCA for this unit? On the SB3, iirc you stated RCA was a tiny bit better.

Thanks Sean,
Dan

seanadams
2009-09-03, 21:31
Well if you helped them to get the S/PDIF right, then that's great for us running our own dac's (and digital Panasonic head units).

I haven't been in the loop on this for a long time, but I have high confidence that it was done well. The electrical part of it is basically the same as for Transporter's RCA output - a discrete flip flop reclocks the s/pdif signal on the way out. Touch does s/pdif in software sort of like SB3, but a big ARM SOC is a somewhat hostile environment for the clock path, so clocking it away from the main die was called for (similarly, SB3 does this in a CPLD). Ultimately, s/pdif performance will be at least as good as SB3 and not far from Transporter, although all the products are extremely good in this regard.



Do you have any info on the comparitive jitter of optical vs. RCA for this unit? On the SB3, iirc you stated RCA was a tiny bit better.


TOSLINK (as observed at a receiving device) is always worse, like +100 to 200 ps regardless of how good the source is. Coax is the only way to go if you care about jitter, although optical has the advantage of being inherently isolated which could help in a system having EMI or ground loop problems. That's why you get both... Vive la différence. ;)

pichonCalavera
2009-09-03, 21:49
The specs look quite nice. I love my SB3, but I would not mind buying a Touch if it has better Sound quality. And then finally I will get the chance to listen to some 96 material :)

mauidj
2009-09-05, 16:07
Yes I also am very happy with my SB3 but am super excited about being able to hear some HiRes material....without having to splurge on a Transporter.
Looks like I have my Christmas gift sorted :-)
BTW...just have to say a big mahalo to all the SD/Logitech guys who answer our questions so openly and honestly.
Such a great community!

martens
2009-09-06, 10:38
Does its USB port can deliver enough current to feed 2.5" HD in external case?

Labarum
2009-09-06, 11:37
And the big question: how does it sound without an external DAC?

funkstar
2009-09-06, 11:59
Does its USB port can deliver enough current to feed 2.5" HD in external case?
the USB port supplies the standard 500mA @ 5v, so yes, it will power most 2.5" HDDs in enclosures.