How good of a DAC is the Logitech Transporter
Hi Raymond, Yes, that is correct; the clock jitter coming from the S/PDIF receiver (all digital inputs) is very high compared to the low jitter clocks used for the wireless. IMO, this is the major reason why many prefer audio stream from their computer/server against a CD transport. Of course, IMO again, a CD transport can sound better than computer audio, but that is another story. :-) Best, Alex Peychev |
i doubt i would be able to hear the difference though, i mean between wireless and wired. i know the Transporter doesn't have USB, but how would USB compare to network or S/PDIF performance wise? as high end as the Transporter is, it's a shame Logitech/Slim Devices forgot to include something as simple as an USB, which even a dirt cheap transport/streamer would have one these days. |
I believe a USB solution would still ultimately involve an S/PDIF conversion operation - and thus there would be no reason to use USB with a Transporter. A main feature of these SlimDevices units is to avoid any such S/PDIF conversions - the network connection avoids S/PDIF and gives an optimum connection medium. Also, regarding whether there are "better" AKM dac chips available, keep in mind that Sean Adams (designer of the Transporter) implemented the chosen AKM dac chip in a very optimized way. Here's a quote-snip from him: Sean Adams: "However, in the case of Transporter there is a very large improvement over the manufacturer's specs because we are using the chip in a far more advanced design than AKM's evaluation board. For the THD+N figures this is especially due to the jung regs and the selection of certain passives in the amps/filters. The clocks are very important too, but this isn't meaningfully reflected in THD+N tests." |
I've been evaluating the Hiface USB to S/PDIF from M2Tech. With my asynchronous DAC, the Hiface considerably outperforms my Transporter (both upgraded or stock). The Hiface was connected to my Sony VGN-SZxxx Sony Laptop streaming wirelessly audio files from the same server used by the Transporter. Player is Foobar with KS plug-in. As for the DAC/Analog stage of the Transporter, it is the same as in the AK4396 datasheet recommended circuit for balanced + single ended output (page 35, fig 17). As you can see, there are coupling capacitors at the DAC outputs and NJM5534D Op Amps. "However, in the case of Transporter there is a very large improvement over the manufacturer's specs because we are using the chip in a far more advanced design than AKM's evaluation board." I think I'll point AKMs attention to this statement. :-) Best, Alex Peychev www.aplhifi.com |
Alex, your Hiface/DAC outperforms the Transporter, maybe because your DAC is simply better but not because Hiface USB-S/PDIF is better than network? Fiface is more a convenience device instead of an enhancement, right? if i stream wirelessly (or via ethernet) from my laptop to the Transporter, then i don't think using an USB-S/PDIF would improve over network, right? |
Alex, i see... I know the Transporter is only capable of 24/96 natively, will it make it 24/192 by simply adding a Hiface interface? i mean, ultimately you will need to use the Transporter's digital out to go into your DAC, is that digital out 24/192 or 24/96? i am interested in your experiment, let us know your findings please :). best regards raymond |
Raymond, the Transporter is limited to 96K so adding Hiface will not help. Even when used as a digital source to an external DAC, the Transporter still can't do more than 96K. Of course, the newer Slim Servers make possible the playback of audio files with higher resolution, but these are being down-sampled to the 96K limit. What you can do is experiment with a Hiface plugged to your laptop, feeding the Transporter digital input. In this case you will have 192/24 capability. But as I previously mentioned, the clock quality will be greatly decreased because it will come from the digital input receiver that uses PLL for the clock recovery. In other words, you will not be able to hear the full capabilities of the Hiface. I will let you know about my findings once I complete the evaluation but, so far, at equal playing fields, I strongly prefer the Hiface. In fact, I like it so much that I will be using M2Tech USB interfaces in my digital products. Best, Alex Peychev www.aplhifi.com |
Thanks Alex! Sorry but I am still confused at one thing. You mentioned: "the Transporter is limited to 96K so adding Hiface will not help. Even when used as a digital source to an external DAC, the Transporter still can't do more than 96K." But then you also mentioned: "What you can do is experiment with a Hiface plugged to your laptop, feeding the Transporter digital input. In this case you will have 192/24 capability." What is point of feeding the Transporter with 192/24 if the Transporter is only capable of 96/24? I think I might be missing something here. Regards Raymond |
I am sorry for the confusion, Raymond! When used as a network player (wi-fi or LAN), the Transporter is limited to 96/24. This is due the processor they are using, I would guess. When used as a DAC with its digital inputs, the Transporter can do 192/24 because the DIR (Digital Interface Receiver) and the DAC chips (both made by AKM), are capable of this resolution. Best, Alex Peychev www.aplhifi.com |
got my Transporter last week, have been testing it with my Denon AVR 4810 and some cheap speakers while waiting for delivery of my ATC SIA2-150 integrated amp (to go with the ATC SCM40's floor standers), so i guess i can't really comment much yet except to say that so far i found the TP built-in DAC no different to the Denon built-in DAC's when playing 2-ch music (i was hoping an improvement), but then again i am only using a dirt cheap dvd player as transport (one of those $50 chinese no name ones), so maybe no point concluding on anything yet... however, i have a problem, the knob in the middle does not always respond to "click" (push) - it's intermittent, sometimes works, sometimes doesn't, does anyone know why?? thanks in advance! cheers raymond |
