ECdesigns

[opus101]

I'm a bit active on that thread as I design NOS DACs - 'soft bass' I would attribute to being a bit noisy in the lower frequencies. The noise could easily come from the power supply or it could be inherent in the DAC architecture itself.

[opus101]

11 hours ago, Michael L said:

I cannot understand how a cable can add jitter. I know it means pulses will be more rounded off due to multipath propogation but I don't see how pulse timing can jump about.

 

Have a look at this document, it explains how bandwidth limitation leads to jitter.

 

http://audioworkshop.org/downloads/AES_EBU_SPDIF_DIGITAL_INTERFACEaes93.pdf

[opus101]

1 hour ago, fas42 said:

This, is a description of how amplifiers work - power is shared between the output devices, say semiconductors, and the load - there are numerous ways of doing this, which gives all the classes of amplifiers.

 

 

Their description is rather reminiscent of single-ended classA amplification. The active element (triode, transistor) is arranged to shunt the load so the total draw from the power rails is constant. The difference here is that the active element is a powerDAC of some kind.

[opus101]

42 minutes ago, hopkins said:

 

.... before making assumptions about how it works, don't you think? 

 

 

Have I made some?

[opus101]

2 minutes ago, hopkins said:

If you want to challenge what ECD writes in their document and explain on a public forum that they are wrong then have the courtesy to pick up your phone and discuss it with them first... Thanks 👍

 

Curious - what makes phoning them first with detractions a courtesy?

[opus101]

Volume controls add noise, that's inevitable as they're resistive by design. The noise is proportional to the square root of the resistance so lower resistance means lower noise.

 

Another possible means for SQ degradation via a volume control is if the ground terminal (the left one when facing a pot) is connected to a noisy ground. Grounds get noisy when fed common-mode currents, single ended connections are the worst offenders as the 'ground' terminal does double duty.

[opus101]

You can listen on Tidal for free - https://listen.tidal.com/view/pages/single-module-page/ae223310-a4c2-4568-a770-ffef70344441/4/889e7c2a-e3be-472b-9801-bf6b40655050/1?artistId=11474

[opus101]

44 minutes ago, One and a half said:

 

@Superdad 1.4V is OK with a moderately high gain preamp, no? In the Hovland days, this level would have been the norm? That's 0.707V rms, something.

 

He actually said 1.4V rms which is only 3dB down on the standard 2V rms of CD players and DACs.

[opus101]

19 hours ago, hopkins said:

 

- the powerDAC generates a sine wave analog signal using what is called "zero order hold" -  the sample value (voltage) is kept constant until the next sample. Sine wave signal now looks like a stepped sine wave signal. The consequence of zero order hold is slight trebles roll-off (approx. -3dB). Trebles are not boosted, so there can be slight trebles roll-off depending on speaker, room modes and listening position. This trebles roll-off can be easily corrected by the speaker. The Tangband W8-2145 offers such trebles boost (see datasheet), this way trebles are reproduced correctly. Most multi-way speakers already have an attenuator circuit on the tweeter because the SPL of a tweeter is usually higher compared to the SPL of midwoofer and woofer. So this L-pad attenuator can be easily adapted for 3dB trebles boost. Speakers can also be corrected externally using a simple filter (resistor in parallel with a capacitor, in series with the speaker).

 

As a designer of NOS DACs for many years, I take issue with the claim that NOS droop is 'easily corrected'. It can be easily corrected only in a very approximate way, to correct it more accurately isn't easy. The shape of the boost curve isn't one found in first order slopes, it takes at least a 2nd order system and then the curve only fits over a part of the boost range. 3dB boost only applies at a frequency of 20kHz, below that the boost is lower, falling to 0.1dB around 5kHz.

[opus101]

Yes I agree, the frequency response deviations of speakers in rooms are generally of a greater magnitude than for electronics. I'm not taking issue with the overall solution, merely with the particular claim I addressed.