Conflating D and A
Join Our Community Subscribe to Paul's PostsIn yesterday’s post on tone controls, there were a number of comments about the use of DSP, yet few about the differences between analog and digital controls.
There is no question that if one is happy staying entirely in the digital domain, DSP EQ and correction is a near-perfect solution. We can design extensive tone controls that have zero phase shift and are sonically neutral.
The same cannot be said for analog. And therein lies the rub.
If you’re going to add tone or EQ controls to an analog preamplifier you are going to suffer added circuitry, phase shift, and sonic degradation. That’s just the cost of doing business in the analog domain.
As a manufacturer, we have to be sensitive to all our customer’s needs. We can’t, for example, produce an honest analog-based preamplifier with DSP for EQ. To do that would require the analog signal to first be converted to digital and then back into analog.
Which is why blanket statements about EQ and tone controls are difficult. We first need to set the ground rules of the playground before making blanket statements.
Just sayin’.
For me yesterday’s focus was „the need of tone controls and the dependence or not from the evolvement of gear quality“. It’s interesting to look on differences between analog and digital EQ‘ing.
I also understood so far, that DSP EQ‘ing must be less harmful, although when hearing opinions about realizing bass EQ‘ed speakers, I also often perceive similar constraints as about analog EQ‘ing.
What’s interesting is, that all mastering engineers working in the analog domain use analog tone controls when producing the media we play on our stereos (while we then avoid doing the same for purity reasons 😉 )
Indeed! Thus both, the sound engineer and the end-user try to “improve” the sound quality tweaking on the wrong end. Should at first recording engineers improve the recording techniques for avoiding the GIGO principle? I often was told that with the introduction of more sophisticated tools in the mixing consoles in the 60th the efforts for optimizing the arrangement of the artists/orchestra around the microphone within the recording studio were dramatically reduced. And should the end-user at first optimize the quality of room acoustics, set-up and mains power supply before fine-tuning via DSP based EQ?
Paul,
I agree with you about not having tone controls on high-end gear for the reasons that we all know & that you have brought up in various discussions from time to time.
And it is exactly for those reasons that I did not even use a pre-amp for 22 years.
Obviously my comments on last night’s topic about having at least a treble gain control on my amp these days are due to where my personal preferences lie in audio at this point in my life.
Earlier last year you did hint that PS Audio was ‘noodling around’ designing a DSP (digital domain A.I.) type of unit, which is all well & good in maybe 2-3 years.
However, I still strongly believe that it would behoove (behove) (behooove) your company to produce part of the Stellar ‘Strata’ (integrated amp) range with the best available analogue Bass & Treble controls until such time as you can go full digital…if you’re really serious about increased sales.
Prospective buyers will then have the option as to whether the incremental difference in imaging is worth not having the flexibility of tone controls…& vice versa.
Either way it will equate to more sales, allowing you to balance your passion for high-end audio with increased profits & product saturation…I mean let’s be clear here; you are also a business.
But which business is focused? The business of selling „audiophile“ (whatever this means) gear or of selling high fidelity (high-end?) gear? High fidelity means highest accuracy (no phase shifts, perfect step response, flat frequency response, minimal noise/distortion, point source or line source loudspeaker designs, etc.). Following this business case would require a new cap from PS Audio not labeled “audiophile” but “high-ender”! 🙂 I would join the second camp! That’s why the range of my PS Audio components is still limited to PPPs, Quintessence, Noise Harvesters, a P10 and a PHGC while the DS DAC was replaced by a DAC with most sophisticated internal DSP features.
ps,
“But which business is focused?”
I would hope that the whole business (the business as a whole) is focused, regardless of which products are on offer.
It would be very interesting if PS Audio made 50% of their Strata amps with high quality analogue tone controls & 50% with gain only & then to watch the resulting sales numbers in each camp over a two year period.
Agreed! I have some recordings that could really use some tone controls:) If a studio records it that way and it just a bad recording, then how do we fix it?
P Squirrel
Did you go all RME?
Just askin’.
@ FatRat
Or at least a “tape loop” to insert a Loki.
FT,
Yes, well if you’ve got the ‘tape loop’ at the back, & most still do, then you’ll always have that option, although I think that that is less ideal than having the tone controls as part of the internals.
“As a manufacturer, we have to be sensitive to all our customer’s needs. We can’t, for example, produce an honest analog-based preamplifier with DSP for EQ. To do that would require the analog signal to first be converted to digital and then back into analog.”
It seems that if you are hung up about having an analogue audio system, forget about DSP and EQ. This seems slightly old-fashioned given virtually everyone has had digital in their systems for almost 40 years.
The fact is that DSP and EQ are digital processing techniques that can be used to solve a myriad of problems and make any hifi system sound better and shape the sound to the listener’s preferences. It’s just not something that PS Audio have got involved in as most of their products are analogue and the digital ones just do basic D to A conversion.
There are of course loads of manufacturers who make these devices or build in the required processing. You can do quite a lot of EQ in Roon without buying any hardware. A dealer near me sells loads of Illusonic units, a ‘Swiss Army knife’ digital pre-amp that can fix and adjust just about anything, but is correspondingly complex and usually requires the manufacturer to measure the room and programme the system. My system includes a programme called Sweet Room that requires the room to be measured and EQ settings to be put in a file and copied to the SD card that slots into the machine, so you need a microphone and a computer. There are products from the likes of miniDSP and the very popular Anti-Mode units from DSPeaker that have been around for years.
So once again blanket statements are not a good thing.
It’s up to each manufacturer and their respective customers as far as tone / DSP capabilities go. Apparently doing things in the analog domain is fraught with issues. Doing things in the digital domain is “near perfect”.
How would someone imagine inserting tone / dsp controls in the current PSA product line?
So to read between the lines the rub comes once a certain max PCM sample frequency is reached, and for especially those those who lean towards DSD.
So if digital tone control / dsp is the answer then one has to live with fact that playing an analog or DSD source is going to require a format change.
So again in the end it’s up to the consumer and whose product / direction they choose.
You can add them in the DAC, or in his streamer if it ever sees the light of day.
We run ours in JRiver on a Mac mini.
Repost:
A very important aspect to this not discussed so far is the concept that linear in-room response just doesn’t sound very good. “Flat” in-room response can sound thin in the bass and too bright in the treble. We don’t listen in anechoic chambers or with speakers buried in a field.
Thus, “target room curves”, as studied and documented at length by Harman, B&K and others sound most natural to most listeners. These curves typically slope up +6db from about 200down to 20hz, and decrease about 4db from 1khz to 20khz. That’s a 10 db downward tilt in total!
Although most dsp room correction systems provide for target room curves, well designed tone controls as found in McIntosh and others can go a long way to achieving a natural response. The idea that “we don’t need tone controls because our equipment is so good” ignores the room the equipment is in. The speakers and room are essentially one component.
“Accurate” vs “Musical”? I’d argue that you can come close to having both or at least an acceptable tradeoff.
A very helpful first step is to run REW and learn about your room, then treat, use tone controls or dsp to achieve an appropriate target curve, then sit back and enjoy!
That’s precisely the way we went. Even In Paul’s Copper articles they recommend this.
Every time I think about “upgrading” from my decidedly mid-fi system, I read topics like this. Then I put music on and if it’s a recording that needs help, I activate the tone controls on my amp, which cause absolutely NO sonic degradation. (Yes, I know…not a “resolving” enough system…the blanket answer for everything.)
When you say activate your tone controls does this mean your mid-fi amp allows you to by pass its tone controls? I wish that manufactures of hi-end analog preamps would include hi-end tone controls that could be by passed. I know this would add cost to what are already ridiculous prices, however, I personally would be willing to pay for this. I would say about 10% of what I listen to I would like to tweak the EQ even though I would introduce phase shift in my all analog amplification system. The desire to tweak the EQ is because ( in my opinion ) the recording was not EQ’ed properly in mixing or mastering. I would rather have the choice to adjust EQ than not.
Yes…they can be taken out of the circuit altogether.
ADC DAC?
Shannon Parks Puffin
Logical path after the valved Budgie.
What really maters in the end is the sound not measurements. If one cannot hear it then it does not matter what the measurement show. Take for example digital audio. Super measurements but sonically inferior to analogue. The trouble starts when an analogue signal is chopped up and reconstituted to resemble the original. To add insult to injury quite a bit of of the signal is deliberately left out. As for mixing analogue and digital it will always result in degradation of sound because analogue when converted to digital and back to analogue results in addition of distortion at every stage in addition to which signal is deliberately lost. So it’s best not to mix analogue and digital. Why mess with what is natural just to make it artificial ? Music is analogue. The question is , why does digital not exist in nature ? Is it possible that now that people are up to their necks in digital they are sticking to it just for the sake of it ? Regards.
And you hear this? Blindly?
I guess nobody would deny today that digital photography has a better resolution than the retina of our eyes with its limited number of photoreceptors. Is the visual center in our brains a DA-Converter or is it all about pattern recognition and reconstruction of an image based on limited data and memory (see also visual illusion)? And what is different different in our hearing system? We also see a limited number of inner hair cells in the cochlea! 🙂 Thus maybe the challenge is to get reconstruct the “audibly relevant” information from a recording/loudspeaker allowing to create the relevant audio patterns?
-Sometimes I’m here to learn new things.
-Sometimes I’m here to gain clarification or reassurance on things I’m fairly knowledgeable about.
-Sometimes I’m looking for justification to buy a new toy or for a toy I’ve already bought.
And sometimes Paul nails it & checks off all three in one post.
This is why I’m here. Daily. With appreciation.
Thanks Paul!
How many audiophiles DOES it take to screw in a light bulb…..?
I’ll say it again…
Everybody has SOMETHING that they spend WAY too much $$ on, that makes everyone else raise an eyebrow & say – “Pfft – you’re an IDIOT”
“How many audiophiles DOES it take to screw in a light bulb…..?”
Not sure how many but first you’ve got to rewire it with top quality cabling and ensure a decent power supply. Then you’ve got to treat the room, then…..and on it goes 😉
As a 20th century analog person in a 21st century digital world I’m the first to admit I don’t come close to fully understanding, why isn’t an A/D –> D/A system treated the same way as an analog black box two port zero phase system where amplitude and phase on a full Bode plot are directly related? So if you can really build a zero phase shift filter circuit in the digital domain why not just do away with oversampling and build a zero phase shift anti aliasing filter of 1000 db per octave at 20.5 khz? Ted, get ready to twang your magic FPGAs at a CD. It would make a real bang in the industry.
https://www.youtube.com/watch?v=H35odPm7b3w
Hi Paul.
This isn’t a response to your post but I didn’t know where else to post this. I read your first book, 99% true and enjoyed it very much. I have looked forward to your latest book, Audiophile’s Guide and checked every few days on Amazon to see if it was available. Seeing that it is now available I was going to buy it until I read 3 out of the 5 reviews that said the book was basically unreadable because of the “typesetting” or formatting of the Kindle edition. One of the reviewers actually attached a photo of one page that showed no spaces between the words and words at the end of a line being cut off. Will this be corrected, and if so do you have any idea when? Btw, I owned a couple of your first products, the moving coil amplifier and the preamp. Both were great for the money, which convinced me to purchase two M700’s for my system. It’s hard to believe they are class D.
Thanks and I look forward to your response.
No worries and thanks for reaching out. You can always email me [email protected].
Yes, the poster was correct that the first release of the Kindle was F’d up. My bad. I am still learning.
It is absolutely fixed and thanks for asking. If you do get the book I’d appreciate a review that says it’s been fixed. :). They won’t let me comment.
Any modification of frequency response requires convolving samples over multiple points in time, whether analog of digital. This begs the question of what point in time you “correct the phase” to. I have not heard any of this “phase corrected equalization”; rather, I have demonstrated to my satisfaction that musical information is encoded in waveshapes that any frequency shaping degrades – including the affect of sound waves traveling over 50 feet as in large halls. All EQ inherently smears waveforms, degrading the extreme transients embedded in real, live music (+18dB in the top octave).
As for consumers “preferring” controlled tone, I see this as poor correction of problems that don’t fit on a store shelf. Room acoustics need to be corrected architecturally, building interiors designed with listening rooms that neither contribute nor detract from recorded content.
SORRY, this will not look like “Clean, modern interior”. Rather, it will look more like the interiors inhabited by the patrons of our musical evolution, i.e. Renaissance and Baroque era European royalty (or African/Asian royalty). Those who paid the luthiers, composers and musicians determined “good taste” in music and furnishings. This was a good thing, because those patrons also received music lessons and counted in their ranks many professional level musicians and even some composers, creating a virtuous circle. Modern architecture and interior design is hopeless, and nearly everybody has ears developed using bad audio and acoustics. (some agree with me that contemporary musical tastes are also hopeless!)
The next problem is that speakers typically have spatial radiation patterns that do not resemble any known musical instruments, and are not anywhere close to flat. Dunlavy, Linkwitz, Putzeys and the crowd at Meyer Sound address time response and spatial response, Thiel was better than most. Blackmer achieved good waveform on axis. Mainstream speaker design measures and controls frequency domain response on the tweeter axis, and then wonders why it doesn’t sound right. EQ is the wrong way out of these problem, full stop.