I must say I prefer the good 'ole settings for engines 3 and 1 over the low sfs. Engine 3 actually sounds more 'musical' (the Peter Dutch style) to me.

The low sfs seems to add a bit something, but for some reason after some listening I feel a lack of something else. Ok, this is vague but I dunno what it is. It somehow wears fast.

I'm going to wait for v07 and apply the settings in their proper fashion.

Regards, Coen

Hi,

I'm breaking in here since this thread got me thinking. No, not about balanced isolation transformers, I'm far from that point yet, but about having the PE (not peak extension) of the NOS1 and PC on the same connection.

Since my computer PSU blew up, I've been having difficulty with getting the sound back I was used to. I tried several PSUs that should even improve on things but all I got was worse sq.

Then in a flash of Zen I swapped the powercable from the PC that sounded fine even on its mobo codec (the ATOM) to the XX music PC and voilá very nice sound again, I dare say even better than before. And this was just a standard cable.

So what was the matter? I inspected the power cable and it looked a little worn on the euroconnector part. Measuring the wires showed that the cable was not making any contact the PE pin!

Now that the PE is tied to the PE of the powerstrip and hence to the NOS1, the SQ issue is solved. Interesing though is that this loose PE connection did not bother me with the other -blown- supply (or did it blow because of this defective cable?).

I am shure there is more to be gained on this topic, but so is in optimising XX!

regards, Coen

Hi,

On a more technical level, the currents from the inpot voltage are flowing to both phases to the outputs because of the pinch resistor.

So current on the plus flows also through the pinch to the minus output (and input throught the 3k5) and current on the minus via the pinch to the plus output (and input). These currents are summed at the output, hence the blending of positive and negative currents (iaw attennuation of the phases).

Note: to clarify the above, this is when either the plus or minus has the positive voltage. The increased current through the series resistor will cause the attenuative voltage drop at the amplifier input impedance. On the negative leg this positive current will cancel some of the voltage developed across the amplifier input impedance.

No groud is involved. It is not nessessary and is a lot harder to make symmetric (maintaining the balanced nature of the signal).

Since signal current flows through the pinch resistor, i would presume that quality would matter here. Such is also my experience with the se shunt (to ground) attennuator. Since the current will be less than through the series resitor(s) one might argue that is is less important (but not unimportant).

Imho you are trading of dac liniarity for resistor noise, parasitics, hf cutoff and thermal issues. The constant low output impedance of the dac also will do no harm. Furthermore resitors do distort measurably, as you can ee one of the linear audio magazins.

Regards, Coen

Well,

I'll give it a shot.

The pinch resistor kind of short circuits at the output.

 When volume is completely down, plus and minus are tied together at the output. Input "sees" 3k5 to ground on each phase, impedance at the output is zero ohm.
When completely up, the driving device (DAC) "sees" the 3k5 in series with the input impedance of the amplifier (600 ohm per phase?). This will allready act as a voltage devider.
In between the "pinch" resistor is parallell to the 2x amplifier impedance. The smaller the resistor value the more both phases are short circuited, the more the signal is attennuated. The same thing but in different wordings is saying that the more attennuation, the more the plus and minus are summed at the output pins. Complete summing leads to zero signal at the pins!

Attenuation range is probably limited and the pinch resistors will be small in value (which is advantagious since these are dominant for the output impedance of the attennuator).

I can't think of a simpler balanced attennuation device.

Regards, Coen

P.s in the single ended community this circuit is known as a "shunt" attennuator with a fixed value resistor in series with the signal. (my personal preferred way of building an attennuator dispite some obvious theoretical drawbacks).

Hi,

This looks like a fully balanced control to me. Two 3k5 resistors from input to output for each phase and a "pinch" resistor on the (very nice) switch.

Off course neither the input nor the output impedance is constant. It varies with each volume setting. But that being constant was not claimed i presume.

Regards, Coen

Peter are you stating that having the music on a seperate usb3 drive is a significant change? (for the 'better' ?) Is this from a convenience or also from a sq perspective?

I have limited sata connections so having no or a negative drawback  when migrating to an usb3 hub would suit me very well.

Regards, Coen

Hi,

I would check out the rap on the Electro Harmonix KT90 and Chinese or Russian KT120.

Seems to be a wonderfull sounding direct replacements for the KT88/6550.

regards, Coen

Hi

Disabeling the powersaving functions of the cpu does not help for latency (or sq for that matter).

What helps for the idle latency is disabeling the HPET timer. From avg 40 to avg 9 uS . When playing XX with below settings the latency rises to 400uS (indeed at apprx half the timeres) .
Is this normal for NOS1 on USB3 PICe or might it indicate that the pc is somewhere not optimal?

Updated the USB driver to the latest version, but that does not matter.

regards, Coen


EDIT:
400 uS is for playing with 4mS NOS1 buffer
220uS @ 2mS buffer
80uS @ 1mS buffer (totally cracked sound)

So there is some 1:10 ratio between driverbuffer and dpc latency.

Above latency with 24/48; with16/44.1 latency is a bit lower @ 380uS. Throttling back the AP from 16x to 8x reduces the latency to 220 (for 16/44.1).

Everybody has different dacs and xx settings. Wasn't special mode all about low latency?

Peter,

Latency when playing is a little lower with 1066Mhz than with either 1333 or 800.

Right or wrong, i dunno. I much prefer the more focussed and dynamic and "musical" sound when in 1333.

How to manage the latency? Practically no mobo tweaks applied (graphics to 400 Mhz). I allways got the impression this board is a little slow. Gonna update some drivers soon.

Regards, Coen

Regards, Coen

Checked the latency on my music pc.

With nothing started by me, I get the following latencies:

35-57 for 1333
21-50 for 1066
37-60 for 800

Looks like 1066 is the sweet spot here. Seems to sound a tad more relaxed than 1333 or 800 also.

regards, Coen

Edit: with xx playing latency is around 350. Best sound, no contest, is with 1333 setting.

Sorry, I was very unclear. I just meant the 16x AP setteng where the cracking occurs.

If you start the nos driverpanel you have to select the 'errors' branch and see what has happened (or happens) during the cracking noise.

Regards, Coen

Johan,

Report Peter of the NOS1 driver errors when playing with the 48x16 setting.

Regards, Coen

Dc is a bitch for linear supplies. With all this switching around these days it is hard to avoid. No wonder people like gear with double C-core or R-core transformers (those are airgapped).

Maybe you can control the fan in  voltage mode and have a different current draw from the psu.

regards, Coen
 

Interesting stuff as usual.

A 50Hz rattle? So that is originating from the mains and not from the rectification peaks on the secondary, which would have given a rattle of 100Hz.
There must be some dc or ac ground loop created here that saturates the core (toroids are especially sensitive to this). In that case the ac  magnetic fields stray out and can cause movement of magnetic parts causing the hum (at a 50Hz pace). I allways thought the saturation was caused by contact-rectified switching HF on the mains, but then you would have noticed it again on the second pass.

Very hard to figure out what ac loops do in this case without a proper amp and connection scheme. Do your amps have a dc blocker?

Regards, Coen