DACs and ADCs in AVP-700?

[jigesh]

I don't yet own Arcam, but am looking into AVP-700. I hope this is the right forum to post.

Some prepros, like Cary Cinema 6, use single DAC chip per channel; some, like Anthem AVM30, use stereo DACs (one chip per two channels). I was wondering if anyone has more information on the A/D and D/A converters in Arcam AVP-700.

The google search led to some contradictory information. For example, Ultimate AV review says that "...the AVP700 uses a single chip that is a combination A-D and D-A for all eight channels, with integrated volume control on that same chip. Although balanced outputs are provided the circuit isn't a true differential design—the single-ended signal is converted to differential by Burr Brown transformer-less line drivers..."

While the Home Theatre Magazine review says that "...The connection highlights, however, are the 7.1 channels' worth of true, dual-differential balanced outputs (XLR)..." - no mention of DACs here.

The official product data sheet mentions "Wolfson Microelectronics 24-bit 192kHz, DACs, stereo ADC and precision electronic volume controls"

Is there any relay clicking while detecting inputs/locking to the detected signal ? If so, how loud?

Thank you.

Jigesh

[Exirion]

First of all, the AVP700 contains Wolfson 8740 DACs <----- edit: apparently I'm wrong... they use one chip for 8 DACs/ADCs and volume control.

My HTPC system has a bad habit: it disables the spdif output when there is no sound. When a sound is played, the spdif enables and this causes a click in the DACs of the AVP700. It can be annoying when the volume is not low. On the other hand, I think it's because they left out muting electronics, which is better for sound quality.

I would like to have information on the XLR outputs too. I hope it's not true that they used additional electronics (Burr Brown chips) to produce the balanced outputs. I plan to use the balanced outputs soon (building a killer amp with 6 mono units, each with its own power supply), and if there are addition components in the signal path maybe it's better to stick to the unbalanced cinch outputs.

Can anyone from Arcam give information on this? Maybe even better:are there electronic circuit schematics available?

[jigesh]

Thank you. If someone from Arcam throws some more light, like, how many Wolfson DACs/ADCs? One per channel or one per two channels or some single-chip implementation for all eight (7.1) channels like the Ultimate AV Review says?

Edit: Thanks, Exirion. I read your edited post which answers my question on the number of DACs/ADCs. Thank you.
Now the question comes to my mind is: Can a single-chip solution affect overall channel separation in the sound field? I am asking this because almost everyone who has this prepro raves about its two-channel performance compared to the HT performance; probably because less the number of channels in a single-chip solution, less the inter-channel interference/cross-talk (if any).

[Exirion]

Originally Posted by jigesh

Edit: Thanks, Exirion. I read your edited post which answers my question on the number of DACs/ADCs. Thank you.
Now the question comes to my mind is: Can a single-chip solution affect overall channel separation in the sound field? I am asking this because almost everyone who has this prepro raves about its two-channel performance compared to the HT performance; probably because less the number of channels in a single-chip solution, less the inter-channel interference/cross-talk (if any).

After some googling I found out that the Arcam AVR300 uses the WM8770, which is a multi-channel DAC/ADC with volume control. Another option, but less likely, is the WM8768. Pretty sure the AVP700 uses the WM8770 as well.

I own a CD73 CD player and the performance of the AVP700 in the analogue domain is very satisfactory. I use the CD73 with analogue connections. Sound is good and so is the stereo image. If it sounds the same with the XLR outputs I'm very happy.

I think you can endlessly debate about the whole "discrete vs integrated" issue. The truth is that integrated solutions have become much better through the years, so I guess resistence against integrated components is also a matter of psychology

I bought the AVP700 as an upgrade after a NAD T-163 A/V processor. Stereo music has the highest priority for me, but having fully seperated setups for stereo and multi-channel A/V was a bit too radical. I consider the AVP700 a very good trade-off

[jigesh]

Originally Posted by Exirion

...I think you can endlessly debate about the whole "discrete vs integrated" issue. The truth is that integrated solutions have become much better through the years, so I guess resistence against integrated components is also a matter of psychology ..

I guess I have to agree. Also, my suspicion was just speculative; may be if exact data-sheet specifications are known, the interchannel X'talk specifications may turn out to be at par, if not lower, than the discrete solution due to technological advances in monolithic integration. Besides, at audio frequencies, the channel isolation may not be as hard to achieve compared to that at higher frequencies (say, RF).

[Exirion]

Take a look here:

http://www.wolfsonmicro.com/products/WM8770/

http://www.wolfsonmicro.com/products/WM8740/

On the right you can download the datasheet. It contains a lot of information