DACs and bass response?

Shadorne - I think the problem lies in where jitter is measured.  Most manufacturers measure it at the oscillator or even use the spec sheet oscillator number.

What I'm talking about is measuring the jitter of S/PDIF signal as it arrives at the DAC.  I have never seen direct measurements of this, except what I published.  Companies that make Transports, converters, reclockers and servers all need to measure this directly, but they don't.  They don't need to clip probes onto chips to do this.  They need a 75 ohm termination inside the scope or AP equipment.

Measuring jitter inside the DAC, say on a I2S bus from a USB or Ethernet converter makes a lot of sense, but it requires measuring both the bit clock and the Master Clock.  The D/A can use both of these or either one to affect jitter.  I doubt if this is done in this J-test.

Steve N.

Empirical Audio

Since you are clearly able to build a device that takes 800 psec jitter from an Oppo and turn that into 20 psec jitter with your Synchro-Mesh, then why do you believe that nobody else has a DAC that can correct incoming jitter to completely inaudible levels - around 20 psec or less?

Good question.  The answer comes from 10 years of modding equipment, seeing the circuit boards exposed in these DACs and hearing them at shows.  I don't see the things implemented in DACs that are required to achieve these low jitter numbers.  It's not just selecting a low phase noise oscillator, or providing a dedicated power supply for it.  It goes WAY beyond that.  It has taken me 10 years of modding and tweaking on my own products to learn these tricks.  And I don't hear the SQ that would result in exhibit rooms at shows if they had implemented these optimally.

After I retire in a few years, I may write a technical book so that other designers can benefit.  I have thought about teaching a course at a college, but I live in the sticks.  For now, these are trade secrets that differentiate my products.

Steve N.

Empirical Audio

In general I found that there is a trade of between mid/high to low dynamics and not only in Dacs, gear that sounds very detailed and ’sweet’ (strong at mid and high) doesn’t peoduce strong punchy bass and in contrary gear that has accurate and tight bass tends to be less detailed and musical at the mid/high section.
In general I prefer to sacrifice a little bit at high/ mid to achieve strong and tight bass .

This is not inherent in components, it is a function of the design.

This has everything to do with 2-3 things:

1) values and placement of decoupling caps

2) types of decoupling caps, ie; Teflon, Polystyrene, paper-oil

3) jitter

If proper attention is paid to 1 and 2, you can usually have your cake and eat it too.

My 10 years of modding has taught me that many designers don’t understand power delivery, so they pick capacitors just like other manufacturers pick, or what it recommends in the data book of the integrated circuits. Many of the guidelines in data books are only to make sure the circuit functions, nothing to make sure it delivers great audio quality. The errors just get repeated over and over. This is a bit of a black art I have to admit.

Tube equipment is a case in point. Many audiophiles avoid tube equipment because of a "tubey" sound. This is generally due to 2 things: poor choice of tubes and non-existent decoupling caps, particularly for high-frequencies. Designers somehow think that because of the high voltages and low currents involved that these are unnecessary. If they are optimally chosen and placed along with selecting good tubes, it can sound almost identical to SS.

Steve N.

Empirical Audio