CHORD ELECTRONICS DAVE

[Rob Watts]

This discussion has sent me rummaging and I came across: Efficient Convolution without Input/Output Delay

A motivation for this technique is room simulation which can involve many seconds worth of impulse response, resulting in a convolution using 10s or 100s of thousands taps.

Direct multiply-accumulate convolution is extremely expensive in terms of mathematical operations. It is very low in latency.

Ordinary FFT/inverse-FFT based techniques result in a huge delay between the input and output. The delay is reduced by working in blocks. More and smaller blocks result in more mathematical operations.

The paper presents a hybrid of multiply-accumulate with block-based FFT processing to substantially reduce the mathematical cost, while at the same time keeping a reasonable delay. Fig 6 is quite an eye-opener.

Is this the technique you've implemented for convolution, Rob? Or is this technique too heavy on internal bandwidth/memory to be applicable in an FPGA?

 
No I always use the direct form. Within an FPGA generally one is SRAM memory limited not multiplier limited (plenty of DSP's and fabric to make your own dsp cores). Moreover, if I need lower multiplier count, I use a folded FIR, which halves the number of multipliers but gives the identical result. The direct form absolutely guarantees perfect transient reconstruction accuracy too under all conditions.
 
With WTA filters the group delay is determined by the filter needs; you simply can't remove the delay without affecting the filter performance and hence SQ.
 
Rob

 

[Mavwong]

I myself come from Vega. I won't classify Vega as colored, if you use exact clock settings and filter 1 (PCM). It's the most transparent setting for Vega. Upon hearing the Dave personally, I go for it straight and never need to turn back since.
 
Quote:

  Thank you!
I thought so regarding the Analog...
I plan to connect the DAC to my AMP (McIntosh MC275) directly which I do now. Balanced or not is not a major factor for me. I enjoy both at the moment from the Vega while both the amp and DAC are balanced but sound great on RCA or XLR.
The speakers I use are the legendary Yamaha NS-2000. Which are capable of showing all the transparency the rest of the chain has as well as any digital noises and harshness of it. While I already have some beauty of the tubes in the system I would prefer to avoid any rounding and smoothing from the DAC part. Extreme transparency and pace is what I'm looking for.

 

[rkt31]

does anybody have recorded clips of dave's analog out ? sometimes back there was a link of such clips of many other DACs but that link was deleted later on.

 

[rgs9200m]

does anybody have recorded clips of dave's analog out ? sometimes back there was a link of such clips of many other DACs but that link was deleted later on.

There are youtube clips of DAVE playing through speakers, like this one:
https://www.youtube.com/watch?v=RGZ2_Lwjj3Y

 

[rkt31]

@rgs9200m, I have heard those clips. the magic of dave is clearly evident even in the YouTube video but I wanted those recorded clips of various other DACs compared in that link. even a clip of Dave only would be welcome.

 

[Mython]

Kind of a weird thing, don't you think?
 
All the benefits of DAVEs digital-analogue conversion being reconverted by some generic camcorder ADC chip, just so it can be posted on youtube.

 

[rkt31]

@Mython, you are right. actually dave has been elusive in India. it is next to impossible to audition one in India due to its price. they demand full advance payment to procure one from uk. I have heard those YouTube videos. I though even with so low tech equipment the dave's special qualities are evident . in that video it feels as if you are listening to some live performance.

 

[bigfatpaulie]

It's true - I played that video on my laptop speakers and my wife in the other room said, "Wow, the upstream equipment in that recording of a recording is really exceptional!"
 
 

 

[rgs9200m]

Well, it's funny but I detected the flavor of the Hugo TT relative to other DACs via youtube clips of it actually played through my regular Hugo.

 

[Mython]

It just goes to show what a peculiar (and still very little-understood, relatively-speaking) thing human psychoacoustics can be.

 

[ecwl]

@Mython, you are right. actually dave has been elusive in India. it is next to impossible to audition one in India due to its price. they demand full advance payment to procure one from uk. I have heard those YouTube videos. I though even with so low tech equipment the dave's special qualities are evident . in that video it feels as if you are listening to some live performance.

My take is that if you can afford Chord DAVE, once you've heard it, you'll buy it. So the need for audition is psychological.
One approach would be to negotiate with the local dealer. If you're willing to pay them MSRP or slightly discounted MSRP, try negotiating with them to put the dealer/distributor price as a deposit (which is probably 30-40% off MSRP). If you like it when you audition the product, you can pay them the rest for the full MSRP and Chord DAVE is yours. If you don't like it, the dealer can try to sell it to someone else at whatever price they want and once it's sold, you can get your money back. I suspect your local dealer would not mind this kind of a deal since there's virtually no downside to them. And worst case scenario, you'll get your money back in a few months once they've sold the unit they brought in for you. Of course, you could also just book a flight somewhere else and audition the DAVE and take a nice vacation...

 

[Toolman]

Have my Hugo and Mojo, tried to resist DAVE (due mainly to the premium), then I auditioned it. Now I am on the first of my 6 months self imposed fasting to get it.

To my ears, it is that good for me to even placing my order 

 

[musicday]

Hi Rob,
What paint/coat are you using to make Dave's aluminium body black? My concern is that even in the high end watches PVD will eventually peel off.
Thank you.

 

[Toolman]

Hi Rob,
What paint/coat are you using to make Dave's aluminium body black? My concern is that even in the high end watches PVD will eventually peel off.
Thank you.

 
Electro Anodizing?

 

[106099]

  Have my Hugo and Mojo, tried to resist DAVE (due mainly to the premium), then I auditioned it. Now I am on the first of my 6 months self imposed fasting to get it.

To my ears, it is that good for me to even placing my order 

 
Good luck on the fasting, LOL.
How do you like your Mojo vs your Hugo, BTW?
 
paul