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Post by jannick on Aug 18, 2010 12:12:30 GMT -5
Lonnie have previously stated that the XDA-1 can be put directly in front of a power amplifier, since the digital attenuation volume control is so good that the volume control does not have to happen in an analog preamp (for good 2-channel listening).
Will it then make any difference to sound quality, if this digital attenuation is performed on the unit itself, or in a PC connected to the XDA-1 (with the XDA-1 set to fulll volume for example). Assuming you use player software that avoids re-sampling etc. on the pc, will the final signal hitting the DAC chip be the same in both scenarios?
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Post by jlafrenz on Aug 18, 2010 12:23:23 GMT -5
For bit-perfect it is often recommended that the digital out on the PC be ran full volume. Then you would use the XDA-1 to control your listening volume.
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Post by ook on Aug 18, 2010 13:58:53 GMT -5
The output from the computer is 24 bit at best over the SPDIF. If you are using USB I think from what I've read on this board it seems the XDA implementation will be 16 bit which is pretty common.
When you lower the computer volume the computer divides the number it is outputting over the digital out. So if you turn the volume to 50% the end result is to chop the last bit off (divide by 2 in binary is equivalent to a right shift, just like a divide by 10 is a right shift with regular numbers). Maybe this is ok if you are using 24 bit, you can turn the volume down quite a lot say to 1% without losing too much information and still keep all or most of your 16 bit music intact. But you have to make sure the output is 24 bit and your music is 16 bit. I don't know if the DAC circuitry would be otherwise degraded, but the information would more or less be there. If your output is 16 bit then you would lose music information as you turn the volume down. Remember what an 8 bit soundcard sounded like? Well, Thats what you would get at 1/256 the volume using 16 bits.
What I have been investigating is how to equalize the signal on the computer. So far it seems to me the itunes eq stinks, probably done in 16 bit, but my soundcard (Realtek) drivers don't seem to negatively impact the sound probably because I've set my soundcard output to 24 bit. So I'm thinking I could set my output to 24/96 and have a nice equalizer, but save the volume for the DAC. There wouldn't be enough bits to do both.
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Post by jannick on Aug 18, 2010 14:01:54 GMT -5
ook: Thanks for the explanation. Guess that answers it. I was wondering/hoping that the data stream simply contained some sort of volume indication, and was otherwise unchanged. The problem is that the XDA-1 seems (judging from the remote), to only support volume (1 up / 1 down) ir codes. I want it hidden away, and although I can repeat an ir signal, it's a bit problematic when you don't know the level it is set at (imagine comming back later from a high volume listening session, and utilizing another source that has a different volume level). Hmm perhaps better questions would be (Lonnie?  ): - What volume will the XDA-1 start at after being on standby?
- If you mute and then "volume up", do you then get vol 1 or old vol + 1?
- Any discreet IR codes aside from those represented by the standard remote?
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Post by malibujeff on Aug 20, 2010 22:18:23 GMT -5
The output from the computer is 24 bit at best over the SPDIF. If you are using USB I think from what I've read on this board it seems the XDA implementation will be 16 bit which is pretty common. Man I hope this isn't true. I asked several time in different threads for the specs of the USB input but never have seen a response from Emotiva. It will be very disappointing if the USB does not at least up to 24/96 |
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Post by ook on Aug 20, 2010 23:06:04 GMT -5
Well the specs do say USB 2.0.... so maybe that indicates the higher bit rate is supported. The 16 bit limit I think is associated with USB version 1
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Post by jazzinfluenced on Aug 22, 2010 2:57:39 GMT -5
Unfortunately, I believe there are only 3-4 units in the market that can do this. One is the Ayre QB-9, another is the dcs Paganini/Puccini U-clock dac, and I think Boulder makes one, also. All based on Asynchronous technology...the dcs is like a 10% down payment on a $600,000 home. If I'm wrong....someone please correct me.
So pretty much all usb connections cannot handle high-rez except like the ones metioned above. Maybe Ps Audio's Perfect Wave can...I'm not sure? I Know they can use an Hdmi connection and I might be confusing it with that?
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kazoo
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Post by kazoo on Aug 22, 2010 9:44:11 GMT -5
There is one more I have been looking at for a little while. A lot cheaper than the ones you mentioned. I should be able to audition it in the next month or so. Its the Decware MODEL ZDAC-1. I hope the XDA-1 can upscale to 24-bit/192kHz on the USB. I think the XDA-1 looks great and I have a place for it on top of the USP-1. Most of my music is on a hard drive. The ease of making a playlist and having an unlimited music mix is great. The decision will be between these two DACs and the pick will go to the best sounding one.
John
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Erwin.BE
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Post by Erwin.BE on Aug 22, 2010 10:49:11 GMT -5
I hope the XDA-1 can upscale to 24-bit/192kHz on the USB. I think the XDA-1 looks great and I have a place for it on top of the USP-1. Most of my music is on a hard drive. The ease of making a playlist and having an unlimited music mix is great. The decision will be between these two DACs and the pick will go to the best sounding one. John I would be surprised if it didn't. It does not matter which input IMO. Here's the quote from the ERC-1 product page, just replace ERC with XDA since it's the same DAC: "No stone was left unturned in striving to create a player that is superior in every way. Separate, shielded power supplies for the CD carriage, display, and digital and analog sections ensure noiseless operation. Using Analog Devices 1955 DAC, with 384k oversampling, and 1V rms (7V peak for extended dynamics), the ERC-1 will be your guide to rediscovering your CD collection and your love for music. Even the look of the ERC-1 will turn heads, with a sleek faceplate that features a halo-lit slot load mechanism." |
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Post by rclark on Aug 22, 2010 14:21:02 GMT -5
I think Irwin is misunderstanding the OP's question.
Anyway, I won't have this issue as I plan on running the XDA-1 through a high end tube buffer and using the volume control on that instead. It has a tiny tiny tiny output impedance, likely far lower than the XDA-1's so I expect, with my chosen amp, to have a very nice sounding setup whether ERC-1 or pc audio.
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Post by jazzinfluenced on Aug 23, 2010 1:33:18 GMT -5
Hey, Kazoo...thx for the info! Let us know your impressions? First unit I seen at this price. It upsamples the 24/96 but at least it supports it...not to paticular about opamps (are the dacs the same used on the standard oppo bdp-83?)...but I always believe in proper implementation. Very curious...should be good coming from decware (good bang-4-the buck company).
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kazoo
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Post by kazoo on Aug 23, 2010 7:19:44 GMT -5
I will let you guys know. They are having their Decware fest the beginning of October. I will be going to listen to all their stuff. They have some really nice sounding amps and speakers. I have a couple of their amps, but the latest speakers I went with need a lot more power. That is why I bough the XPA-1s. Its nice living 15 minutes away from an audio company.
John
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Post by hobbs on Aug 24, 2010 9:23:20 GMT -5
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Erwin.BE
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Post by Erwin.BE on Aug 24, 2010 10:34:10 GMT -5
Oh! I only ordered a pair of In-Line XLR Attenuators last Friday. These are -10dB fixed and cost €83. So this volume control with XLR seems like a bargain @ $119! |
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