ack's system - end of round 1

[ack]

Thanks Ian; you are welcome to come by anytime. In fact, I want you to, to tell me if I really need Magicos at this point, you personally having gone through so much equipment for your M Pros.

 

[Al M.]

Thank you Al for taking the time to write all this up so well, and I am glad you enjoyed it! Six hours went by really quick.

Yes, that was a really enjoyable day!

Can digital sound like analog? Great analog is undoubtedly high resolution and can be spectacular and lifelike. Digital has theoretical limitations (e.g. see square wave response measurements), but there is now convincing evidence that it is also fundamentally capable of equally spectacular analog sound, even lifelike; and the higher the resolution, the more lifelike it is. Digital theory aside, a huge part of getting digital right is in the implementation, and it's very hard to do so.

It does not seem that there is a theoretical problem with reproduction of sawtooth or square waves from digital, since the ear is band limited. See Amir's post:

http://www.whatsbestforum.com/showt...ral-resolution&p=334892&viewfull=1#post334892

and the article by Lavry who has a solid reputation in digital engineering:

http://lavryengineering.com/pdfs/lavry-sampling-theory.pdf

The extreme high-frequency resolution we hear on your system is audible proof that digital is correct, even from 'only' 44.1 kHz sampling rate. It's just that very few people possibly can have heard such resolution. A bit depth discussion can be had in my view, but a sampling rate discussion? That topic has been dead for me since some time, but after hearing your system this week I consider it even deader than dead. Nyquist was right, and he had always been right. As I suggested to you during my visit, if in 1984 people had been able to hear Redbook CD digital as on your current system, we would never have had the digital/analog debate that we did have over all those decades.

It is worth noting that, while Keith Johnson had been critical about the frequency limitation of 44.1 kHz digital in his HDCD patent, in more recent statements he has not mentioned the idea anymore or even has been implicitly dismissive.

As you say, the problem with digital is implementation. The reason why a higher sampling rate will sound better in some cases is not that it is theoretically better, but that it is on the practical technical level easier to implement in sufficient quality.

My current digital font-end: Despite my Alpha modifications, if you look closely at the DAC, it is a very competent design and execution, though not state-of-the-art. The modifications take it to many higher levels, as you heard, and the need for them became apparent only with the current "Spectral Lab" of amplification (aka 30SV->400RS). Moreover and as discussed, I feel it also surpasses the Rossini that I had at home, in certain areas. At the same time, to get this level of performance, the extra-ordinary Spectral SDR-3000 transport is a big part of this, and I continue to seriously doubt that any computer-based digital feed can possibly come close, certainly nothing with USB written anywhere near it. And mind you, this transport must have been designed over 20 years ago?!??!?

Yes, the idea that there is no jitter from computer audio is only half the story. The other half is noise, noise and three times noise. Computer audio stinks from potential RF and other noise problems. If I'd ever go computer audio I would start with the best Baetis server (with AES/EBU connection), and proceed from there. Just plugging in some computer and hoping for the best doesn't cut it, in my view. To get computer audio as noise-free as your CD digital would probably take you a lot of effort -- on other less resolving systems it might not be as critical, but your system obviously exposes any noise. Fact is, the three best digital auditions (including yours) that I have experienced were all from CD transport; I haven't heard Madfloyd's (Ian's) Vivaldi yet.

Note decay with digital: Simply put, if you lower the noise floor enough - and that, again, implies solid implementation - I don't want to hear that digital cannot do note decay, including proper treble decay. If I have ever said this myself, then I stand corrected.

Yes, the fact that digital can do decay correctly has been clear to me since I got the external power supplies to my amps three years ago, which drastically lowered the noise floor of my system. But hearing your system this week has dramatically confirmed my conviction. This is reproduction on yet another level.

 

[ack]

It does not seem that there is a theoretical problem with reproduction of sawtooth or square waves from digital, since the ear is band limited. See Amir's post:

http://www.whatsbestforum.com/showt...ral-resolution&p=334892&viewfull=1#post334892

and the article by Lavry who has a solid reputation in digital engineering:

http://lavryengineering.com/pdfs/lavry-sampling-theory.pdf

The extreme high-frequency resolution we hear on your system is audible proof that digital is correct, even from 'only' 44.1 kHz sampling rate. It's just that very few people possibly can have heard such resolution. A bit depth discussion can be had in my view, but a sampling rate discussion? That topic has been dead for me since some time, but after hearing your system this week I consider it even deader than dead. Nyquist was right, and he had always been right. As I suggested to you during my visit, if in 1984 people had been able to hear Redbook CD digital as on your current system, we would never have had the digital/analog debate that we did have over all those decades.

It is worth noting that, while Keith Johnson had been critical about the frequency limitation of 44.1 kHz digital in his HDCD patent, in more recent statements he has not mentioned the idea anymore or even has been implicitly dismissive.

Here's the relevant part in the HDCD patent:

Recent research has shown, however, that humans use transient information in sounds with frequencies much higher than [Nyquist] to determine the direction from which the sound has come, and that eliminating those very high frequency components impairs one's ability to locate the source of the sound. The inner ear actually has nerve receptors for frequencies up to about 80 kiloHertz. Therefore, if the "brick wall" low-pass filter, which is a necessary part of all digital recording, removes frequencies above about 20 kiloHertz in transients, it reduces the level of realism in the sonic image.

Now, you then said KOJ "has not mentioned the idea anymore" - perhaps he hasn't, and I have NOT been able to confirm the patent's claim wrt the HUMAN ear; however, I had a thread here years ago (http://www.whatsbestforum.com/showt...r-Cells-responding-to-frequencies-up-to-79kHz) about research on guinea pigs' cochlear outer hair responding to sounds as high as 79kHz (-3dB point), and marine mammals going as high as 200kHz. So until we can prove the same in humans and not just guinea pigs, I'll go with the flow that we can only hear up to 20kHz, but I'll also repeat what I've said to you, that I truly think this limit is a dinosaur.

So the question then is: does it really matter? You referenced Amir's post wherein he says "you ear chops off those extra harmonics [ack: above ~20kHz] just the same. So their preservation [ack: by analog recordings] didn't do one any good since the ear is band limited". I am just not sure that the ear is band limited to ~20kHz, but again, I'll go with the flow...

Great discussion, but meantime, below is the Jazz piano HDCD (RR-114) I was playing when you first came in and which grabbed your attention; I just listened to it end to end for the first time in years, and I was stunned by track 8's ending, with its heavy left-hand activity, and the weight and clarity of the low register notes.

 

[NorthStar]

...And Keith's getting more and more into releasing SACD recordings...even in multichannel (5.1): http://referencerecordings.com/RR_SACD.asp

* Bonus:
? Jazz
? Blues

 

[Al M.]

So the question then is: does it really matter? You referenced Amir's post wherein he says "you ear chops off those extra harmonics [ack: above ~20kHz] just the same. So their preservation [ack: by analog recordings] didn't do one any good since the ear is band limited". I am just not sure that the ear is band limited to ~20kHz, but again, I'll go with the flow...

I am sure that the ear is band limited to ~20kHz, given a mountain of evidence that has produced overwhelming scientific consensus. I am willing to consider extraordinary claims once there is sufficient and relevant scientific evidence for them grounded on sound experimental studies. At this point, there isn't. I don't go by isolated scientific 'anecdotes' that did not produce a credible body of relevant scientific follow-up work.

Under regular circumstances we can no more perceive sounds above 20 kHz -- not even that, as we age -- than we can see UV light (bees do, and they see the world very differently). All the evidence indicates a hard cut-off.

We have had an extensive discussion about this at WBF on the thread where I extracted Amir's post from, page 4 onward:

http://www.whatsbestforum.com/showt...retically-sufficient-timbral-resolution/page4

And I certainly remember the vigorous email exchange that we had some time ago... But I guess, based on what you now can hear from your system, you have changed your views on 44.1 kHz CD since then...

Great discussion, but meantime, below is the Jazz piano HDCD (RR-114) I was playing when you first came in and which grabbed your attention; I just listened to it end to end for the first time in years, and I was stunned by track 8's ending, with its heavy left-hand activity, and the weight and clarity of the low register notes.

Next time I definitely need to listen to this!

 

[ack]

But I guess, based on what you now can hear from your system, you have changed your views on 44.1 kHz CD since then...

I have changed my mind in a lot of ways regarding digital, but not all - a prime example is the dynamic range of a direct-to-disc LP, which I have yet to match with my digital; and obviously, I still think preserving higher order harmonics (above 20kHz) matters.

 

[ack]

Up above, I said:

[There is] research on guinea pigs' cochlear outer hair responding to sounds as high as 79kHz (-3dB point), and marine mammals going as high as 200kHz. So until we can prove the same in humans and not just guinea pigs, I'll go with the flow

Now read the following from one of the researchers at the Howard Hughes Medical Institute (who is one of KOJ's cited authors of an AES paper with Pflaumer), a fellow who specializes in inner ear hair cells http://www.hhmi.org/research/sensory-transduction-hair-cells-inner-ear

On the other hand, mammalian outer hair cells display membrane-based somatic motility that operates to remarkably high frequencies and is implicated by transgenesis experiments in cochlear amplification.

That web page is current as of February 2016, and although he is not directly referring to humans, it looks to me that his research is still geared towards proving or disproving that humans can or cannot *respond* to (not necessarily directly hear) such high frequencies. Until such day, I continue to postulate that any recording and playback technology had better preserve ultrasonic information, despite all the body of evidence that says we cannot hear above 20kHz; I see no logical reason why technology should not preserve all instrumental harmonics up to 102kHz (or whatever has been measured), and why we shouldn't let the ear be the ultimate limiting factor, as is in a live unamplified performance. Hi-rez digital can do that as can analog, but RBCD cannot.

 

[YashN]

below is the Jazz piano HDCD (RR-114) I was playing when you first came in and which grabbed your attention; I just listened to it end to end for the first time in years, and I was stunned by track 8's ending, with its heavy left-hand activity, and the weight and clarity of the low register notes.

Bowie's pianist for decades.

 

[ayreman]

ack, many of your components are modded. Some, like your speakers, are heavily modded. How come your REL Stadium III still remains in its rather primitive stock state? I own a pair of REL Stentor III and have already put them through 2 phases of modification with outstanding results. Phase 3 is due in February this year. When and if you open the back plate of the sub, you will be appalled with the primitive parts there. I threw all that out and put in the good audiophile-grade parts instead.

 

[ack]

ack, many of your components are modded. Some, like your speakers, are heavily modded. How come your REL Stadium III still remains in its rather primitive stock state? I own a pair of REL Stentor III and have already put them through 2 phases of modification with outstanding results. Phase 3 is due in February this year. When and if you open the back plate of the sub, you will be appalled with the primitive parts there. I threw all that out and put in the good audiophile-grade parts instead.

Excellent observation and question; I was using the sub as a resting table for most of these years. It was only recently that I was able to integrate it; and yes, I will open it, finally. Thanks for the heads up on the parts. How exactly did you modify yours and who did the mods? Don't tell me there are more electrolytic caps in there :-( The other issue is that I've been thinking about a Magico S sub.

 

[ack]

Here's the REL board - I don't see anything worth modifying, so really curious what you did. Nice and neat, in a sealed enclosure of its own, very modular, quite impressive for $3000 list price back then.

 

[microstrip]

10000 microfarad Aerovox capacitors? First mod - at less 47000 microfarad low ESR!

 

[ack]

What's exactly wrong with Aerovox in this application??? Plus, they are supposed to be extremely high performance. You do realize these are expensive film capacitors, not your typical electrolytics. I also play the sub at extremely low volume, crossed at 25Hz. I am thinking I'd rather see if I can get an S Sub for $10K or less.

 

[ayreman]

How exactly did you modify yours and who did the mods? Don't tell me there are more electrolytic caps in there :-(

I am new to this forum and don't know how to attach photos. Can you tell me how? Or give me your e-mail address to send the photos of the mod job done on my Stentors. I have an excellent engineer who's been modding the **** out of my entire system with outstanding results (I'm a linguist, not an engineer). The subs are 80% complete. Hopefully by early spring he'll be totally done with them.

Regarding electrolytic caps... In the Stentors there are 4 large output caps in each sub of poor quality. We threw those out and put Mundorfs in instead. Replaced 2-cent speaker wires connecting drivers with PCB with AQ Mont Blanc cable (soldered to the driver, of course!). Replaced stock power inlets with Furutech. Replaced crappy wires connecting Neutrick inputs with the PCB with PSS conductors taken from AQ Fire interconnects. Bypassed Furutech power inlet with Mudorf Supreme cap (1mF) and added a truckload of Audyn Cap Plus caps into all types of power circuits (around 100 mF into each sub).

If you do the same to your Stadium, you will forget about Magico S forever.

 

[ack]

I am new to this forum and don't know how to attach photos. Can you tell me how? Or give me your e-mail address to send the photos of the mod job done on my Stentors. I have an excellent engineer who's been modding the **** out of my entire system with outstanding results (I'm a linguist, not an engineer). The subs are 80% complete. Hopefully by early spring he'll be totally done with them.

Regarding electrolytic caps... In the Stentors there are 4 large output caps in each sub of poor quality. We threw those out and put Mundorfs in instead. Replaced 2-cent speaker wires connecting drivers with PCB with AQ Mont Blanc cable (soldered to the driver, of course!). Replaced stock power inlets with Furutech. Replaced crappy wires connecting Neutrick inputs with the PCB with PSS conductors taken from AQ Fire interconnects. Bypassed Furutech power inlet with Mudorf Supreme cap (1mF) and added a truckload of Audyn Cap Plus caps into all types of power circuits (around 100 mF into each sub).

If you do the same to your Stadium, you will forget about Magico S forever.

To attach pictures: When you respond to a post go to Advanced, then click this:


Then upload the files you want from the pop-up menu:


Meantime, here's some info from the manual, which is what I see:

The capacitors are high quality nitrogen filled polystyrene types of 1% very close tolerance and an indefinite life. The use of very close tolerance components also ensures consistency of performance throughout the production life of each model. Great care is taken over the star earthing to maximise sound quality. There is further filtering of the higher frequencies to ensure optimum performance at all settings of the ABC. The built-in power amplifier is built onto a separate circuit board and uses ultra rugged audio grade MOSFET output devices. The power supply is the engine house of the amplifier, the smoothing capacitors [ack: those Aerovox] are long life with very low equivalent series resistance (ESR), the bridge rectifier is very conservatively rated at 35 Amps. The transformers are ultra quiet audio quality toroids with very low losses, these are especially manufactured to our strict specifications. Great care has been taken to deliberately over engineer all REL products to ensure ruggedness in service. This ensures an exceptionally robust, long lasting device.

 

[microstrip]

What's exactly wrong with Aerovox in this application??? Plus, they are supposed to be extremely high performance. You do realize these are expensive film capacitors, not your typical electrolytics. I also play the sub at extremely low volume, crossed at 25Hz. I am thinking I'd rather see if I can get an S Sub for $10K or less.

No these are not expensive film capacitors, they are common electrolytic. I have used them decades ago in DIY tube applications. They are not from the US Aerovox company, but from an UK company and are now called BHC Aerovox, and labeled as BHC. Most UK made amplifiers from the 80s and 90s used them and the first think we should do when we get equipment with them is replacing the electrolitics - I had seen several many failures in old british equipment. Sometimes they have less than 10% of the original capacitance. Probably more recent capacitors have better reliability, the ALS30 was a decent capacitor, but not exceptional and surely not "audiophile quality".

BTW, although conrad johnson use film capacitors in amplifier power supplies, they are tube equipment fitted with output transformers. It is not physically or economically possible to use film capacitors in a solid state subwoofer amplifier.

 

[ack]

Thanks. I will call the US Aerovox tomorrow, they are 20 mins away from here, see if they can look up by part number to confirm or refute. On the board, though, these caps are bolted on, like you would any US Aerovox of that size (they are HUGE for their capacitance and rated voltage, much larger than the 10K uF/63V Mundorfs I put in the DAC, making me think they are film, not electrolytic).

 

[microstrip]

Thanks. I will call the US Aerovox tomorrow, they are 20 mins away from here, see if they can look up by part number to confirm or refute. On the board, though, these caps are bolted on, like you would any US Aerovox of that size (they are HUGE for their capacitance and rated voltage, much larger than the 10K uF/63V Mundorfs I put in the DAC, making me think they are film, not electrolytic).

You have the capacitors and the datasheets at HifiCollective, a known UK DIY supplier - please see http://www.hificollective.co.uk/components/bhc-standard-electrolytics.html and for the datasheet of your capacitors http://www.hificollective.co.uk/sites/default/files/bhc-als30-datasheet.pdf.

BTW, they are decent capacitors - but your were asking for ways of upgrading, and picking better quality and larger electrolytics and seems the logical path.

 

[ack]

OK that settles it, thanks again. Let me see if Mundorfs would fit in there, and if not, they probably fit off board, in the enclosure.

 

[ack]

So the Mundorfs don't fit in the enclosure, and obviously neither the board - they are 9cm D x 10.5cm H, really huge. I will have to house them in an external box, drill a hole on the backplate, and run wires. Doable, and it would be best to use a detachable umbilical with the right size connectors for the type of current involved, and I am not sure if there is room for such a large connector on the backplate; otherwise, wires would be sticking out of it... Need to think about this, and start with the right umbilical connector first.

It seems like it would be easier and best to just take out the entire backplate and house it in a new external power supply box, with two outputs for the woofer wires. The problem is I need to find someone to do the cut-out of the external box to fit the backplate.