DAC64 question

Hello everyone

Sorry if I'm retreading old ground here - I've had a look thru the old posts and can't find the precise answer I'd like. Could someone help me out ??.

I have a MkI DAC64 with a new Denon DVD-2900 as transport. I like the combination very much.

I have nearly always used my DAC64 on the one-second buffer setting [the four second one sounds a little "slow" to me]. To be fair I haven't used the DAC with no buffer much at all, save for when I play DVDs through it, for obvious reasons - must have partly been down to all reviews/opinions saying that the DAC64 sounds ropey with no buffer, I suppose.

When we were up at Definitive the other day though Kevin Scott told me that he'd used the DAC64 at various shows and in his opinion it sounded better with no buffer on. We switched the buffer on and off during a short dem and to tell you the truth I couldn't tell a lot of difference. Perhaps I have cloth ears.

I'm using a optical cable between the Denon and DAC64 and it sounds to me thru my system as if there isn't much between the no buffer and buffered settings.

Does anyone on the forum hear a huge difference between non-buffered and buffered ??. Should buffered AUTOMATICALLY sound better ??. If, as I understand, the buffered setting reduces the influence of transport/digital cables on the sound, does it mean that supports for the transport/"pure direct" transport modes [ie switching out video circuits] are of little or no use ??.

Sorry for the long post.

Paul

 

The buffer setting makes no difference according to the designer. It was added in to circumvent an issue with long-term use (digital radio perhaps), not for audio reasons.

 

Interesting question Paul. TBH, I've never tried my DAC64 on anything but the 4s buffer so I can't say whether there's any difference. The theory behind the buffer is to eliminate the influence of the transport/digital cable by eliminating transport/cable induced jitter as the data is clocked out of the buffer by a separate local clock that is in no way linked to the clock signal on the input. When using no buffer, the DAC effectively runs of the transport clock signal. Rob Watts, the designer of the DAC64, says there should be no difference in sound between the 1s and 4s buffers and that the 4s buffer was there to allow more time for a potential buffer underrun/overrun resulting from slight differences in the transport clock speed and the DAC's local clock speed.

If you're hearing little or no difference between using the buffer and not this would imply that your transport and digital cable have very low jitter characteristics. If you were using the buffer then I would see no benefit in using the Denon's option to switch out the video circuits as any potential jitter the video circuits might introduce would be got rid of by the buffer anyway.

Hope that helps.

Michael.

 

The data is reclocked on being received, so it is buffered to some degree no matter what. All that the buffer setting does is dictate how many cycles of the DAC64's clock it remains in the buffer memory before it is read out and used.

Rob has conceded that it is possible for the DAC64 to be affected by transport, but only by the RF interference conducted into it. Using an optical connection avoids this.