Hopkins' System

hopkins

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A "reviewer" or influencer (whatever that is) has low credibility in my book if there isn't a turntable in his room. After all, what's the point?
Good thing I am not a reviewer :)
(I do have a turntable, but not a fancy one, and essentially listen to digital)
 

hopkins

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After watching this video...


I was curious to listen to the demo track on my headphones, so I looked it up. Why is the album titled "Jazz"? I listened to another track of his - a cover of "Take the A Train". It was awful! Why Chesky produces this is a mystery to me, but some may enjoy it - I just don't get it:


I could not start my day on this sour note, so I took a few minutes to listen to this version on YouTube on my phone.


To get good sound, you need a good recording, a good instrument, but also a good player. Ellington's "touch" on the piano keys comes across even when listening on a phone.In this chaotic world, his music sets things straight and gives me clarity...

Have a nice day!
 
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hopkins

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Glad to see a happy new owner of the PowerDAC-SX!


I'll be curious to see what others have to say about "source immunity", in particular, even though there is no doubt in my mind (as confirmed by my tests) that this product provides great sound with a basic digital source (like my WiiM Pro). How did ECDesigns achieve this? High level technical information is available on their website, and those curious to dig further can always contact them. They have some proprietary solutions dealing with noise reduction in the DAC...that's the name of the game when it comes to digital signal processing. But there are many other aspects that make these products unique and worthy of attention!
 
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hopkins

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By the way, source immunity means that any digital track will sound the same whether played from a basic (bit-perfect) source or from a high end player (ex: Taiko...). Examples of "basic" digital sources:
- a CD player
- a phone with a bit-perfect player such as Android's USB Audio Player Pro
- a computer (laptop, desktop, raspberryPi, etc ..)
- a streamer (WiiM in my case)

It also means that the same track played from your own file will sound the same if streamed (ex Qobuz, Tidal...) - provided the tracks are from exactly the same version. I have been able to verify this over the past few months - but there are so many cases where better mastered versions are available on CD that one has to be very cautious in these comparisons.

It is obviously not a cure for poor sounding digital masterings. They just won't sound worse when played from a basic source.

Having said that, how do these new DAC/amps compare to other often more expensive components from other audio brands? I don't know, I have not made comparisons and I don't feel the need to do so. Hopefully, for people interested in these products, others will.
 
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hopkins

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I feel less lonely (when it comes to "audiophile" matters) after reading this report from a powerDAC-SX customer:

"The SX really works magic with the Omega super alnicos. And doesn’t seem to mind what feeds it. So it doesn’t get much simpler than this. I enjoyed the journey to get here but I can say this is my last purchase. So glad I trusted the reports of the new models."

So that makes two of us :)
 

hopkins

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Just saw that ECDesign's products are now distributed by Elise Audio in the UK:


This should give them more exposure and the opportunity for some to audition these innovative products in the UK.

That customer I mentioned confirmed in his feedback (on AS) the source immunity I was referring to. A milestone for digital audio?
 
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hopkins

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I found another stunning version of "Take the A Train" posted by Loren Schoenberg a few years ago on Sound Cloud, and titled "The wildest Ellington piano I've ever heard"!

https://soundcloud.com/loren-schoenberg%2Fthe-wildest-ellington-piano-ive-ever-heard

This seems to have been recorded at a dance date in California in 1958. As far as I know, it has not been released.

Ellington was having fun, probably waiting for the crowd and musicians to settle in. The lengthy (5 minutes) piano introduction is unique and fascinating.

I downloaded it to save it preciously:


Enjoy!
 
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hopkins

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Posted this in another thread.

Lester Young and Nat King Cole duelling in 1945.

Nat King Cole is smoking hot, and Lester Young was and always will be the President...

I love the "raw" sound that the powerDAC-SX and Altec speakers offer.

The transparency into the recording brings out the essence of the musical performance. The limitations of the original recording quality are secondary.

Perhaps I am biased because I love this music so much?

They don't make em like this anymore!


Enjoy!
 
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hopkins

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That track is discussed in this video (you can watch the whole video for more context):


You can check out how he tickled the keys on this video, for example:


There are still some unreleased recordings of Cole jamming in clubs in the 1940s. What a shame these have not been made available...
 

hopkins

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More fun with the Altec 755C:


Based on the model described by our esteemed forum member @je2a3 here: http://jelabsarch.blogspot.com/2012/06/open-baffle.html?m=1

It is not quite finished: need to add the square piece on top, round out the crudely cut opening, then probably reinforce the panel in the back (choice of wood was constrained by currently short supply of Baltic birch) and make a second one to listen in stereo...
 
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hopkins

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The sound fills up the room incredibly well, with a single speaker, and it sounds great. Very clear sound. I'll wait until I setup the other speaker to compare with the Silbatone-type boxes, but so far I like what I am hearing.

My living room is long (11 meters) and opens up to a terrace. Even when sitting outside, the clarity of the sound is impressive!
 
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hopkins

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Given my enthusiasm for these speakers, I have given some thought, obviously, to acquiring a pair of 755A.

I dare say that price is not the issue - these are speakers that I would certainly enjoy for many years (I am 57...). How do we put a price on that? The 755C put a big smile on my face every time I listen to them. Then I close my eyes and just drift into the music.... There is no need to say more.

The issue, as I have found out already with the 755C, is the risk involved in purchasing them.

A 5 star vendor on ebay does not guarantee anything, as most of these sellers just move these products and are not qualified to evaluate them... So one would have to find a good pair from a specialized vendor, and chances of that happening are now incredibly slim.
 
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hopkins

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I feel compelled to provide some comments on this post speculating about the PowerDAC-SX' "bass performance", posted on another forum:


Seems like these questions arose to some extent from watching my videos. As I have explained before, the bass performance in my videos is the result of other factors than the amplification:
- the TangBand drivers I use roll-off around 40hz based on their specs
- my open baffles are narrow, actual frequency response is different from the driver's specs (measurements probably made with wide baffles)
- room modes contribute to muddying bass response at several frequencies (my measurements confirmed this).

It is curious to me why anyone would evaluate an amplifier demoed on a YouTube video without considering the speakers used... The end result is a product of the entire system, and the room (especially when it comes to bass response). And I am not a pro with a perfect listening room, but I am happy with sound :)
 
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hopkins

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I am really enjoying playing mono tracks on a single Altec speaker. As a result, I would like to automatically tag my digital albums to identify which are stereo and which are mono. This is something I have been meaning to do for a long time. Unfortunately, it is not so simple...

You can listen to tracks, but it is not always so simple to decide whether it is true mono or not (see below).

There are a number of tools that can help.

With Audacity, or other audio processing software, you can check by inverting one channel and adding it to the other. This is a manual process.

This command line utility is interesting: https://indiscipline.github.io/post/zrtstr-eliminate-faux-stereo/
If the stereo WAV file is identified as Mono, then you can generate a WAV file containing a single channel - there is no real advantage to doing this, aside for reducing the space (by half) occupied by your music files. Single channel files will be played on two channels by most, if not all, commercial players.

You can also write scripts with FFMPEG - see this discussion, for example: https://superuser.com/questions/1635775/how-do-i-check-if-a-2-track-wav-file-is-really-in-stereo

But the real difficulty in identifying mono is due to the fact that there are always small discrepancies between the left and right channels. So how do we decide at what threshold a track is really mono?

I analyzed that Sun Ra track, "Possession", which I linked to in a previous post. It was recorded in 1956. The original album "Jazz by Sun Ra" was issued in 1957, and there is no indication as to whether it is a mono or stereo album: https://www.discogs.com/release/517197-Sun-Ra-Jazz-By-Sun-Ra-Vol-1

You could purchase the original LP (pehraps there is some mention of the recording in the booklet), but you will have to spend at least 1000$ (up to 3000$) and none of the currently listed items are sold with the original booklet...

Subsequent versions, both on LP and CD, were issued in either stereo or mono. Were the original master tapes mono, and some stereo effect added during mixing on later re-issues?

Listening to the track either with headphones or speakers, it is not obvious to decide whether it is truly Mono.

Looking at the waveforms on Audacity you can see small discrepancies if you look carefully:

Possession stereo.jpg

Running that FFMPEG script (ffmpeg -i Possession.wav -filter:a "pan=1c|c0=c0-c1,astats=measure_perchannel=none:measure_overall=RMS_level" -f null /dev/null), results in an average difference between left and right channels of -35db. That is very low.

I inverted and summed the tracks in Audacity and here is the result:

Possession diff.jpg

Here is the resulting track if you want to listen to it: https://storage.googleapis.com/cloudplayer/Possession Diff.wav

I would assume, at this point, that the original track was recorded in Mono, but that some messing around was done afterwards to issue it as stereo.

Running that FFMPEG script on the Mono version of Miles Davis' "Kind of Blue" reports a difference of -178 dB.

Running that same script on a 1937 Andy Kirk track, from the Chronological Classics CDs, results in a difference of -48db. The recording in 1937 was definitely mono!

A threshold around 40db may be sufficient to identify true Mono?

Anyway, I think I will use that method (FFMPEG script) to identify mono tracks. I will first store in my tags the db Difference calculated by FFMPEG, and then decide on the threshold for which I consider the files to be mono, and add an additional tag to identify them.

That Sun Ra album, by the way, was produced by Tom Wilson - interesting guy - you can read about him here: https://en.wikipedia.org/wiki/Tom_Wilson_(record_producer). There is also a website dedicated to him: https://www.producertomwilson.com/
 
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