A toast to PGGB, a heady brew of math and magic

[Nenon]

I joined the PGGB group when @Zaphod Beeblebrox, @austinpop, @ray-dude, and @romaz were still developing the product and have been a witness of it from the very beginning. The intention was for me to provide more feedback, but I was working on my server at the time making changes all the time and did not have a proper reference to evaluate PGGB in a meaningful and consistent way. Rest assured, the team did an amazing job providing feedback to @Zaphod Beeblebrox and voicing the PGGB noise shaping. 

 

I've tried many different releases of PGGB. It was okay in the beginning. But then it started getting better and better. The development process was good and annoying at the same time. Good because it was definitely going in the right direction and PGGB files sounded better and better. Annoying because there was a new release almost every week, and I had to redo my files over and over again and keep multiple versions of them. 

 

Most ot the time this process was pretty straightforward. @Zaphod Beeblebrox provided some new improvements. Everyone liked them. And he implemented them into a new release. Every major new release sounded better. But then it got a little tricky. As the granularity of what could be done in PGGB increased, personal preferences kicked in. One person liked more transparency, another liked fuller sound, another liked more air, etc. At that point @Zaphod Beeblebrox added many options. During the private beta I've seen some people getting obsessed with so many options. You could go nuts with all these options. A lot of useful feedback was gathered in the private beta. So much that I could not keep up reading it... Eventually all that was concised in a simple but extremely powerful interface. 

Just giving that behind the scenes background info may give an idea of the effort it went into the development of PGGB. 

 

The most important thing to note, which was already mentioned several times, is that PGGB is not for every DAC. Highly recommended to read this: https://www.remastero.com/pggb.html#dacs

 

I bought a Chord DAVE DAC only so I can do some power supply experiments and tests. Didn't like the stock DAVE at all. But after replacing the stock power supply, it got a lot better. Then I realised that feeding the DAVE with 16fs files made it sound better (as it bypassed the upsampling internally). And then I tried PGGB, which made it even better. The combination of all these 3 things turned the DAVE from an average performing DAC to something incredibly musical. It completely transformed the stock DAVE, which to be honest I have no idea why people even like. I'd say PGGB is a must for DAVE owners. And I can absolutely see how PGGB would boost up the sales of Chord DAVE DACs!

 

And a final comment - I play my PGGB files with HQP (in a bitperfect configuration). The combo works great. This is good for everyone. A lot of choices and they all work together. Chord DAVE DAC sales would be boosted. HQP sounds incredibly good playing those offline upsampled files (and your computer does not need to do realtime processing). And also use HQP or HMS to upsample files when you stream. PGGB cannot do it. The way I look at this - these products complete each other rather than competing. 

[Nenon]

@Juice Hifi - can you please share what your reference audio system consists of? 

 

[Nenon]

6 hours ago, Juice Hifi said:

I am way past the point where my own system  s are the reference systems that I base my conclusions on as far as Audiolense goes. And for the last 15 years or so I have been more concerned with my clients’ sound quality than my own.

But I have 4 systems where I have built the speakers myself. Drivers are Accuton, TC Sounds, DC Gold and one tweeter I can’t remember. Three of the four have sand-filled walls for the midrange and up. Highly recommended. Power amps are class D and B, although I have a pretty potent class A in idle. My preference is class D. Converters are two from Lynx Studio, embedded, and Hypex’ dsp module that came with their plate amps.

My best speakers are a 3-way with 2*Acuton and an awesome 10” driver from TC Sound … from before TC became famous. The TC plays with ease down in the 20s. 

 

I don't know a single person with a reference system of the level of  @romaz or better who liked digital room correction. Not a single person. Why? Because at this level absolutely everything matters and makes a huge difference. I visited @romaz and listened to his system last month, so I have a pretty good idea of what it does. I've heard those Wilson Alexia Series 2 speakers you see on his photos many times before but never as good as they were in @romaz's system / room.

And in a system of that level, digital room correction done the traditional way makes a lot more bad than good. This is the first time I am getting feedback that digital room correction is done right... with PGGB EQ. As an early PGGB adopter, I can absolutely believe that.


My issue (or at least one of many) with time domain correction is very simple. Measurements are not perfect. Microphones are not perfect. You start with a far from perfect (in my opinion) measurement and do quite aggressive "corrections" based on something that is WRONG to begin with. Yes, there are many expensive and really good measurement systems one might say. They are not perfect in any way. Our brain is much more sensitive than we think. Can those excellent regarded measurement systems show why every USB cable I have tried sounded different? NO, they cannot. Can they show me why ethernet cables make a difference? No, they cannot. Can they show me why a network switch makes a difference? No, they cannot! Should I keep going? If they cannot show us such differences how can we trust them to "correct" the music in our room? Does the mic cable need to be of high quality? No, you would say... But I would argue why the USB cable in my system makes such a big difference then... Okay, I already dropped a huge bomb here, so I may very well continue, but I will end this paragraph here. 

 

As someone who has spent the last several years trying to build and perfect a digital source, I have a lot of issues with the way digital room correction is implemented in general. At the level of perfection of the digital source I am after, there are many unacceptable things involved here. One of them is the software player. Realtime upsampling and realtime digital signal processing is another one. And the list goes on. If the sound quality of let's say Roon is acceptable to you, then we are definitely not on the same level and we are speaking different languages. If you are doing realtime heavy processing... same thing. Nothing wrong if you are doing some of that, but you are in a different group than me, @romaz, @austinpop, @ray-dude, etc. 

 

There is no perfect room. Everyone can benefit from room correction, whether it's passive or active. In fact, I consider the room to contribute to about 40-60% of the system. The room is at least half of my system. I have no doubts of the benefits of room correction. The question that remains then is how much harm the digital room correction causes and is it an overall net positive or a net negative result. What you will discover (if you haven't yet) is that in a system with a meticulously built digital source (and the rest of the system of course), the digital room correction the way it's typically done causes more harm than good. That's why in those systems it is characterized as flat, liveless, etc. 

On the other hand, someone using a laptop for streaming or a mediocre server may have a huge net gain. I suspect the latter and people in Pro audio is the current market for digital room correction the way it is done today. What you, Mitch, and other people in the industry do is not acceptable for people like me, @romaz, and others. The only way for you guys to understand why is to come and listen to one of these systems and hear PGGB for yourself in proper environment. Then you will understand. 

 

What @Zaphod Beeblebrox has done is digital room correction done right for that small target of people with not only meticulously built systems but also with meticulously built digital sources. Those of us when asked to describe our systems will have to spend several hours doing a write up and won't just mention the speaker drivers used and the class of amplification, but there will be a whole chapter dedicated on digital source. BTW, my definition of a "digital source" is everything under our control before the signal gets converted to analog - in my system that's everything between the Internet cable coming to my house and the analog output of my DAC. 

 

You guys should learn a trick or two from ZB instead of criticising his work. He is bringing digital room correction to an audience that has tried this before and could not accept as a net gain. He is bringing more business to Audiolense, Mitch, and others. My understanding is he is not interested to be your competition in any way. I will be buying Audiolence soon. I will be consulting with Mitch too. But ultimately whatever convolution filter I pick will be implemented in PGGB. You guys should work together here and bring the best possible to music lovers. I would like to see the pioneers in that field listen to us and become a little bit more open minded. It will help everyone! 

[Nenon]

@StreamFidelity

I expect that at least 90% of the people here will disagree with me. It's a controversial post that will piss off some people. I've done it before and I am sure I will do it again :). Hopefully, my post will not derail this thread too much.

You definitely fall under a different group of people than the group I meant. You are in a group that recognizes the importance of the digital source and you spend quite a bit of time on R&D of your digital source, but you do it on a much tighter budget than people like @romaz. No question you are much wiser than us on how you spend your money and you get way better bang for the buck. But also no question how high the noise floor is from those Keces power supplies and extra processing and how much important information gets buried like dither.  We don't realize this until we hear it.

(BTW, you will hear some of that when you try the v2 of the unregulated LPS with the Taiko ATX powering the EPS and ATX, but that's way offtopic)

 

@romaz and I have a very similar digital source.

Power: dedicated power circuit - Sound Application 240V PGI TT-7 (fed by a Sablon King power cord)

Server: Taiko Extreme with Taiko USB card. (I am not quite there yet)

DAC: Chord DAVE with the latest ARC6 development of the Sean Jacobs DC4 LPS - Audiowise SRC.DX

Software: HPQ (playing bitperfect!) or TAS playing PGGB-ed files.

Network: completely disconnected while playing.

I would probably add a choice of digital cables too but risking to dial the level of controversy up from 800 to 900 (on a scale from 0 to 10) :). Everything listed above is a key component. 

 

Listen to a source like this in a really good system and you will realize how much different it is than what you are doing today. On a system like this messing with even the slightest thing matters! And we are talking about the slightest changes, not anything major. Just to give a couple random examples... You can disable the unused ipv6 protocol on the unused NIC on the Extreme server and the sound will degrade. You can turn on the display on the DAVE DAC and the sound will degrade. You can leave Roon server (unused) in the background and the sound will degrade. Even a few degrees higher room temperature is audible (sounds worse)! 

That's how highly tweaked this system is. I am not even talking about things like using Roon (that makes a huge negative impact) or playing anything different than 16fs files that enables extra processing on the DAVE and reduces the sound quality significantly. I am talking about very little changes. This system is also highly tweaked for super low latency and resource isolation. Imagine what real-time convolution messing with the time domain based on "science" that can't even explain why a USB cable makes a difference can do in such system! It can make it unlistenable even with the best filters. And @romaz has tried that. Digital correction in general can make it unlistenable... you don't even have to mess around with the time domain to achieve that. 

If everyone has a system like this, Mitch, Audiolense, etc. would never do what they do. The good thing is that such highly optimized systems are very rare. For most other people the net gain from digital room correction is very positive and as you say "correcting the timing is very important".

However, not in a system as the one described above. For those few systems out there at that level, PGGB EQ has merits and can make digital room correction a consideration again. 

 

Re: non-calibrated microphone. Let me be crystal clear about that. I would never consider a non-calibrated mic for my measurements. That's not what I meant. What I meant is that even the best calibrated microphone and measurement system cannot show me why things like digital cables that make obvious difference make that difference. Until "measurements" and "science" can show me that, those measurements are far from perfect in my book. And if someone is planning to start a debate on cables, I will not engage in such discussion.

In fact, I am traveling and won't have time for discussions in coming days/weeks. I think I made my point. Not here to argue with the 90% who will disagree with me... just wanted to share my 2 cents. 

 

Lastly, just to be absolutely clear - I am not criticising the pioneers of digital room corrections that I mentioned here. What they have done is genius. No doubts about that. It just needs a little more careful implementation in a highly tweaked system like the one mentioned above, and this is where @Zaphod Beeblebrox and PGGB EQ play a big role.

[Nenon]

37 minutes ago, Juice Hifi said:

They typically have acoustically treated rooms, separate bass solutions with a multitude of drivers, line arrays, open baffle, horns etc, equipped with the finest drivers money can buy, class A or class D amplifiers and studio grade multichannel converters. And they all use active crossovers. The owners are typically highly skilled diy builders who have outgrown off-the-shelf speakers decades ago. They are always on the look for sonic improvements. Some of them have been using Audiolense for digital crossovers and sound correction for 5-10 years. Their systems have been scrutinized for equally long, both through measurements and peer reviews, and Audiolense has gained recognition in the process.

I have to agree that digital crossovers is an excellent application for digital room correction. Since there is already DSP involved, it does not hurt to add room correction. No concerns from me doing it this way. There are many benefits of using active crossovers. In fact, thumbs up for those implementing it this way 👍.

Let's give credit where credit's due :). 

 

52 minutes ago, Juice Hifi said:

In that regard, the last few pages have some of the same traits as a dirty marketing campaign. I just hope that is not @Zaphod Beeblebrox's intention.

I don't think that's @Zaphod Beeblebrox's intention. From my conversations with him on this topic he does not have the time and does not want to deal with measurements and room corrections, but he is open to add this as a standard functionality to PGGB, in a BYOCF (Bring Your Own measurements / Convolution Filters) style.