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ANOTHER Example of Why I HATE DSD and Why Customers Who Bought Sony's Boloney Are So Annoying


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By the way, 60% is about the operating margin on an iPhone - how far along are you with your own design?

 

How is that related to anything? I've spent seven+ years of my career in smartphone industry, so I believe I have some kind of idea how things work there.

 

I also know what kind of margins distributors and dealers expect to get from hifi equipment, so there are no big surprises there either. Of course, after all those margins, 24% VAT is added on top.

 

My own design? Software or hardware?

 

I don't sell any of the hardware I design and build, I spent a year designing my most recent DAC. And BOM is around $1000 (not including case). I'm not stupid enough to try to sell it to anyone, it would cost so much that nobody would buy it.

 

For software I know how many hours of work I have put there and I also know what kind sales volumes to expect.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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I sussed a long time ago that I could build a decent playback system for not a lot of money, the knowledge made me feel that some things are rather expensive from the what is inside perspective. However in the cases where the unit has properly been designed then fair plays it can cost a lot to run an R&D section.

 

If I'd had to name one product where I see price, technology and originality in balance, I would name Devialet.

 

Look inside and you can see that you are actually going to get something and someone has actually spent some time and effort on designing it too.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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If DSD is so darn great then where are all the NEW recordings by major artist ( not classical) ? If DSD was the "go to format" then why aren't the artist demanding their music be in DSD. I surely don't know and it's not on the DSD download sites....

 

In the MP3 market, the biggest and profitable one!

 

From time to time we get something (already CD best sellers) from Analogue Productions and others.

 

I believe Tailspon already explained the other issues...

 

Roch

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Some people like the sound of added distortion, especially from tube amps.

 

The same happens to me with switching amplifiers intrinsic distortion (noise).

 

I've heard these (not Ref 10 though), but could you please explain technically, how adding an extra component between two could improve quality?

 

Non adding nothing to the sound, but with a better impedance matching that most of the DACs I know.

 

Roch

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The same happens to me with switching amplifiers intrinsic distortion (noise).

 

I don't use switching amplifiers, but noise is not distortion. Distortion is correlated with input signal, noise is not.

 

Non adding nothing to the sound, but with a better impedance matching that most of the DACs I know.

 

...and since properly designed power amp has same input impedance as properly designed pre-amp (10 - 100 kOhm), how does that change anything?

 

If DAC is badly designed then that's another story, but pre-amp won't fix it anyway.

 

"Pre-amp" should be called "pre-attenuator" these days, because only vinyl sources require amplification for the cartridge, DAC output tends to end up being attenuated and not amplified...

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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I thought about removing my preamp from the chain, but after a few "white noise" experiences, I chose to use the principle of precaution... I was quite happy that I had my "dimmer" ;) But for sure, having a simpler path should be the way to go...

 

Alain

Alain

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PCM1704 has pretty much hit the performance wall of multi-bit PCM DACs and there are no reasonable ways to improve from there any further. It has about 18 - 19 bits worth of precision. Sabre can do about 22 bits worth, but could perform better by removing all the built-in DSP and performing better DSP off-chip, and if they would focus on the analog and conversion side instead.

Well, actually their THD is -120dB - that is only 20 bit. And Sabre engineers tried hard to "fix" all the faults of the existing D-S designs (see their white paper), to come closer of the true multibit DAC's.

The true 102dB/19 bit resolution (of the 1704 multibit) is actually enough for all intents and purposes.

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I don't use switching amplifiers, but noise is not distortion. Distortion is correlated with input signal, noise is not.

 

I don't know about the amplifiers you use, but saw your Devialet recommendation.

 

Since distortion is noise to my ears, is the same (out of technical and semantic definitions)

 

...and since properly designed power amp has same input impedance as properly designed pre-amp (10 - 100 kOhm), how does that change anything?

 

If DAC is badly designed then that's another story, but pre-amp won't fix it anyway.

 

"Pre-amp" should be called "pre-attenuator" these days, because only vinyl sources require amplification for the cartridge, DAC output tends to end up being attenuated and not amplified...

 

Regarding vinyl sources, we used 'phono preamps' on those days. Then, the following preamp was an attenuator for the phono preamp also. I'm not anymore on analogue.

 

A well designed pre-amp could do magic to some bad designed analogue output stage on some DACs, like impedance matching, even if the amplifier has the right impedance input. I'm very carefully with this since I don't want to use ultra-expensive interconnects trying to compensate impedance matching. Also I feel this is not the correct way (by cables).

 

If we talk about 'digital volume control' I can't find any that match my listening tests exigencies. I never tried it by your music player.

 

Best,

 

Roch

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I thought about removing my preamp from the chain, but after a few "white noise" experiences, I chose to use the principle of precaution... I was quite happy that I had my "dimmer" ;) But for sure, having a simpler path should be the way to go...

 

Alain

 

Sometimes simpler path is not always the best way to go... As the shortest distance between to point is not always an straight line!

 

A very good analogue preamp cost as much as his (analogue) volume control implementation.

 

Roch

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Hi Roch,

 

Yes, there are aspects that seem to need a few turns here and there :) This was a surprise for me, as I was inclined to think the shortest path was the best. I only know that Peter (PeterSt) recommends to skip the preamp with the NOS1, but I am too "chicken" to allow the risk of blowing the speakers if something odd occurs...

 

Regards,

 

Alain

PS: It's like the choice of speakers... I struggle with this, as I have always been told that the source was most important... But all seems almost in reverse now... Yet I have noise coming from the wall outlets that I am using... While I understand the importance of speakers, I still have to get rid of the "grunge" that pollutes the power... (source)

Alain

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A very good analogue preamp cost as much as his (analogue) volume control implementation.

 

A suggestion to those that use preamps. If you're technically handy, use your preamp to establish a comfortable listening level with a selection of music you like as a reference source. Then using a sine wave generator, measure the amount of attenuation the preamp is introducing with a voltmeter. If your interconnects are unbalanced, build a simple L pad resistor attenuation for each channel using like values, and if balanced then a double L, joined together where the single L would be grounded. Arrange the preamp and attenuators in parallel with switches to select either one, and listen for the difference. Regardless of which you prefer, you'll at lease know the signal fidelity change your preamp is introducing.

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Hi Roch,

 

Yes, there are aspects that seem to need a few turns here and there :) This was a surprise for me, as I was inclined to think the shortest path was the best. I only know that Peter (PeterSt) recommends to skip the preamp with the NOS1, but I am too "chicken" to allow the risk of blowing the speakers if something odd occurs...

 

Regards,

 

Alain

PS: It's like the choice of speakers... I struggle with this, as I have always been told that the source was most important... But all seems almost in reverse now... Yet I have noise coming from the wall outlets that I am using... While I understand the importance of speakers, I still have to get rid of the "grunge" that pollutes the power... (source)

 

Yes, based on Einstein Theory of Relativity, is not an straight line the shortest path, but an ellipse...!

 

But please don't ask me for a detailed explanation since I don't even closer by 1,000 kilometers to Einstein mind.

 

My experience with pre-amp attenuators is how they handle the full frequency spectrum, distortion, phase and 'roundness' of the sound at different attenuation levels. Normally the best spec of a pre-amp could be reached at 60-70% of the full output, but this is not an exact parameter.

 

Also, I believe some manufacturers ask you to stay on his DAC volume control because on your savings meaning, but I'm sure this is not the case of PeterSt.

 

Regards,

 

Roch

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Since distortion is noise to my ears, is the same (out of technical and semantic definitions)

 

Well, if you compare white noise, harmonic distortion and intermodulation distortion, they sound completely different...

 

Ultrasonic noise is just inaudible hiss. Are you hearing a constant hiss from class-D amps? It is there even without input signal.

 

I don't know about the amplifiers you use, but saw your Devialet recommendation.

 

It was comment about cost/originality/substance ratio, not a recommendation.

 

I use traditional class-A/B amps. The main amp I use operates in class-A to 10W output power and in class A/B from there. And can spit out 90+ amps of current to challenging speaker loads.

 

A well designed pre-amp could do magic to some bad designed analogue output stage on some DACs, like impedance matching, even if the amplifier has the right impedance input.

 

There would be the same impedance mismatch between DAC and pre-amp too. So I still didn't get the point why there would be less impedance mismatch between DAC and pre-amp than between DAC and power-amp?

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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Yes, there are aspects that seem to need a few turns here and there :) This was a surprise for me, as I was inclined to think the shortest path was the best. I only know that Peter (PeterSt) recommends to skip the preamp with the NOS1, but I am too "chicken" to allow the risk of blowing the speakers if something odd occurs...

 

That's why I'm talking about gain matching. Match gain of the power amp such that it doesn't go too loud even if DAC outputs full level. Then you don't need much attenuation from that level in normal cases. Likely the adjustment range stays within 20 dB. (and in cases of accidents there is no damage)

 

This way it is possible to reduce amount of thermal noise introduced to the signal along the way.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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Well, if you compare white noise, harmonic distortion and intermodulation distortion, they sound completely different...

 

Even if they sound completely different, at the end, is noise (to my ears and not technical skulls).

 

There would be the same impedance mismatch between DAC and pre-amp too. So I still didn't get the point why there would be less impedance mismatch between DAC and pre-amp than between DAC and power-amp?

 

I don't know about how the 'magic' in my pre-amp is done. But compared with several DACs volume control I stay with the pre-amp. I'm talking here about several possible listening levels, and several DACs. And, of course, I tried before a lot of pre-amps.

 

Best,

 

Roch

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...and since properly designed power amp has same input impedance as properly designed pre-amp (10 - 100 kOhm), how does that change anything?

 

Most modern amplifiers have far too much gain to be used directly with a DAC unless some kind of attenuation is used.

Also, many DACs don't like relatively long interconnects due to the higher capacitance. Many modern DACs use an opamp in the output with for example, a series 100 ohm output resistor to help reduce the problems of capacitive loading, but that isn't always quite enough. In such cases it may be better to use a preamp to drive the longer cable to the P.A.

My own discrete Class A preamp is capable of correctly driving a 75 ohm load, so longer cable differences are not a problem if the input of the P.A. is also terminated with 75 ohms.

I don't know about how the 'magic' in my pre-amp is done. But compared with several DACs volume control I stay with the pre-amp. I'm talking here about several possible listening levels, and several DACs. And, of course, I tried before a lot of pre-amps.

 

Best,

 

Roch

 

I agree with Roch regarding digital attenuation. With many DACs, more than 10dB attenuation leads to severe SQ degradation with 16/44.1. 24/96 does of course fare a little better.

We need to remember here, that in a typical domestic situation, the typical power level is often no more than 1W,hence even further attenuation is required.

 

Alex

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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Most modern amplifiers have far too much gain to be used directly with a DAC unless some kind of attenuation is used.

 

This is a problem, because such large attenuation and then again large gain back will just increase thermal noise levels and add distortion.

 

Also, many DACs don't like relatively long interconnects due to the higher capacitance. Many modern DACs use an opamp in the output with for example, a series 100 ohm output resistor to help reduce the problems of capacitive loading, but that isn't always quite enough. In such cases it may be better to use a preamp to drive the longer cable to the P.A.

 

That is a design problem of the DAC and only indicates poor analog design. Opamp itself doesn't make it any worse, there are suitable opamps and current buffers for the purpose and you can also design circuit properly around an opamp. You can also keep power amp closer to the pre and use longer speaker wires because that doesn't cause any problems.

 

My own discrete Class A preamp is capable of correctly driving a 75 ohm load, so longer cable differences are not a problem if the input of the P.A. is also terminated with 75 ohms.

 

My DAC output is designed to be specifically able to handle capacitive loads. I also use cabling (Supra) that has been properly designed to minimize capacitance on interconnects and inductance+resistance on speaker cables. Also shield is correctly connected only from the source end.

 

In addition, I have 30 cm between pre-DAC and power and then more length on the low-inductance speaker wires. This setup goes just fine to 1 MHz without notable attenuations.

 

75 ohm is just 27 mA at 2V output while 40 mA output capability is pretty normal for opamps. My DAC can output up to 400 mA so it can drive 5 ohm loads to 2V.

 

IIRC, JA of Stereophile measures output stages also to 600 ohm loads, which is less than 1/10th of what a proper power amp should have.

 

I agree with Roch regarding digital attenuation. With many DACs, more than 10dB attenuation leads to severe SQ degradation with 16/44.1. 24/96 does of course fare a little better.

 

Why would the input material matter? DAC's internal pipeline is fixed word length, so it is for example 32-bit regardless if you input 16-bit or 24-bit data.

 

But I'm mostly talking about software volume in a player application. I've been testing digital volume controls in various ways. For example I can first attenuate down to -120 dBFS level and then digitally amplify it back and it still sounds completely fine. If -120 dBFS attenuation still sounds fine, anything less will definitely have less degradation...

 

P.S. Now there's a new loudspeaker cable from Supra I want to try out Quadrax at 0.3 µH/m it is very low inductance cable. My current one is 0.4 µH/m and 4.3 Ohm/km. Interconnect is 52 pF/m.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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No, I mean adjusting gain of the power amp, or if not possible placing a fixed attenuation on the power amp input.

Miska ... I'm not 100% sure it is as it appears, but have you come across Leema Accoustics power amps which (they say) are variable gain - though that might just turn out to be a variable attenuation on the input!

 

Eloise

Eloise

---

...in my opinion / experience...

While I agree "Everything may matter" working out what actually affects the sound is a trickier thing.

And I agree "Trust your ears" but equally don't allow them to fool you - trust them with a bit of skepticism.

keep your mind open... But mind your brain doesn't fall out.

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"No, I mean adjusting gain of the power amp, or if not possible placing a fixed attenuation on the power amp input."

 

 

How are you going to make a LARGE reduction in the gain of an amplifier without getting into a lot of major changes regarding VAS stage compensation etc. ?

 

With players such as the Oppo 981 etc. , 10dB fixed digital attenuation very noticeably degraded the SQ of 16/44.1 yet 24/96 was still quite acceptable. Going further than 10dB attenuation noticeably degraded that too.

This was when going directly into my Class A amplifier from the Oppo. It didn't take long to realise the limitations and revert to using a Class A preamp again.

Many commercial DACs simply use opamps as building blocks based on manufacturers published data.Things are quite different in practicce with devices such as the LME49710 etc.though.

Many sound better with more than 100 ohms resistors at the output.Even the capacitance of FETs such as IRF7905 used to replace the now hard to get special muting transistor 2SC2878, which is an NPN transistor with an unusually high reverse hFE of 150 can degrade the performance of many current op-amps. Perhaps it's time to go back to using relays for muting purposes ?

Regards

Alex

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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Miska ... I'm not 100% sure it is as it appears, but have you come across Leema Accoustics power amps which (they say) are variable gain - though that might just turn out to be a variable attenuation on the input!

 

Eloise

 

A power amp with variable gain:

 

B.M.C. Mono Power Amplifier M2 | High End Audio Components - B.M.C. Audio

 

KR

 

matthias

"I want to know why the musicians are on stage, not where". (John Farlowe)

 

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How are you going to make a LARGE reduction in the gain of an amplifier without getting into a lot of major changes regarding VAS stage compensation etc. ?

 

It is not that major change. Alternatively you could place two resistor attenuation on the input.

 

With players such as the Oppo 981 etc. , 10dB fixed digital attenuation very noticeably degraded the SQ of 16/44.1 yet 24/96 was still quite acceptable.

 

I'm sure it is possible to find many badly implemented digital volume controls (not surprising at all for a Mediatek-based device), but it cannot be generalized.

 

It is of course possible to find a lot of badly implemented hardware, but for that reason measurements and looking inside are good.

 

Many sound better with more than 100 ohms resistors at the output. Even the capacitance of FETs such as IRF7905 used to replace the now hard to get special muting transistor 2SC2878, which is an NPN transistor with an unusually high reverse hFE of 150 can degrade the performance of many current op-amps. Perhaps it's time to go back to using relays for muting purposes ?

 

100 ohm output resistor again increases thermal noise and the sound "improvement" is probably mostly due to filter effect in combination with cable and input capacitance.

 

Muting transistors are bad, I use Omron relays. And IIRC, for example TEAC UD-501 also has relay muting. I think my Fostex HP-A8C also has muting relays. Mytek on the other hand doesn't have muting at all.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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Miska ... I'm not 100% sure it is as it appears, but have you come across Leema Accoustics power amps which (they say) are variable gain - though that might just turn out to be a variable attenuation on the input!

 

One of my favorite hardware manufacturers - Accuphase also has selectable gain in their power amps. Four options, 0 dB, -3 dB, -6 dB and -12 dB. Not a huge range, but helps matching volume control range.

 

Their AAVA volume control is also pretty good.

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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It is not that major change. Alternatively you could place two resistor attenuation on the input.

These days they typically use large value input capacitors at the input to retain the advantages of the lower output impedance of the preceding stage for lower noise purposes . Using resistor attenuation there will result in a minor degradation, and possibly why the lower output impedance of a good preamp makes a worthwhile improvement for many. That's also why you don't normally see the lower -3dB point of an amplifier set by the capacitance value of the input capacitor these days

You are more likely to see something like a 22uF Blackgate ( if any left!) or a quality electro of a similar or higher value..

 

100 ohm output resistor again increases thermal noise and the sound "improvement" is probably mostly due to filter effect in combination with cable and input capacitance.

 

That's not normally the reason these days, as some designers specify capacitance values as high as 10nF (!!!) at the output in order to claim bragging rights about how good their distortion figures are..

The series resistor is fitted to ensure stability of the opamp into the capacitive load of a cable. This is an old technique dating back many years, even as far back as the old Marantz CD65 etc. where direct connection of the cable to the front HA PCB degraded SQ. One of the other cures back then was to disconnect the headphone amplifier section. This was even recommended in the HiFi magazines of the time.

The LME49710 and LME49720 are particularly touchy as regards working into even a short cable load.

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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