Multi-Channel, Multi-Amplifier Audio System Using Software Crossover and Multichannel-DAC

[dualazmak]

Hello dualazmak,

i appreciate your work very much, thank you for your excellent and detailed explanations! I want to do the same tests with my speaker-setup. Would it be possible for you to post a screenshot of the actual sine waves so that i can estimate their duration and shape, since i don't have the Sony Super Audio Check CD?

Regards
Yems

Example:
View attachment 240718

Thank you for your kind attention and interests on my time alignment measurements.

I can share various tone signals I prepared for the measurements, and the same for the contents/tracks in Sony Super Audio Check CD. I will PM you soon today or tomorrow.

As for the Sony Super Audio Check CD, you would please also refer to my post here for complete spectrum analysis by Adobe Audition 3.0.1 and MusicScope 2.1.0; in that post, you can also find the PDF booklet (liner notes) in English translated by myself.

 

[dualazmak]

Well, antioxidant and corrosion inhibitor are different concepts that can be related or not, depending on the case, and ascorbic acid can actually be both.

Deoxit is said to be based in Oleic acid. I cannot confirm that as it is not disclosed by the company, but certainly could be and for this example let’s assume it is.
This fatty acid and other different long medium-chain carboxylic are commonly used as corrosion inhibitors (not antioxidants). The way they work, very simplified, is that they attach to the metal surface and form a sort of protective hydrophobic barrier that slows down the corrosion processes.
Oleic acid in particular has an unsaturation in its hydrocarbon chain, and as a result is prone to react little by little with atmospheric oxygen and oligomerize forming the paste or resin you refer to.

Ascorbic acid is a real antioxidant (that is, can donate electrons so that it gets itself oxidized and protects other substances from oxidation. This is a common use of ascorbic acid, for instance, conservative for meat and other things). But besides that it can as well be used as corrosion inhibitor. Similar to the fatty acids, it can also adsorb to the surface of the metal and form a protecting layer.

However the efficiency of any corrosion inhibitor is going to depend on the metal to protect, the corroding medium etc, so it is perfectly possible that in your case the ascorbic acid was not effective enough and you observed some corrosion.

Thank you so much for your intensive follow-up with detailed information.

This is my first time to know CAIG DeoxIT DN5 would contain oleic acid; if it would be so, then your explanation and my experiences/observation could well fit and be validated.

Actually, I am a Ph.D. researcher in organic chemistry, polymer science, pharmaceutical sciences and biochemistry; I can understand well, therefore, your nice info above. I assume your background would be also chemistry and related fields, right?

 

[MCH]

Thank you so much for your intensive follow-up with detailed information.

This is my first time to know CAIG DeoxIT DN5 would contain oleic acid; if it would be so, then your explanation and my experiences/observation could well fit and be validated.

Actually, I am a Ph.D. researcher in organic chemistry, polymer science, pharmaceutical sciences and biochemistry; I can understand well, therefore, your nice info above. I assume your background would be also chemistry and related fields, right?

Yes, I also did Ph. D. in Organic Chemistry (Supramolecular, molecular machines, self assembly) and now I work in the industry (coatings before, composites since some time). Good to see a colleague here
Do you still work? I interact sometimes with some Japanese companies

 

[dualazmak]

Yes, I also did Ph. D. in Organic Chemistry (Supramolecular, molecular machines, self assembly) and now I work in the industry (coatings before, composites since some time). Good to see a colleague here
Do you still work? I interact sometimes with some Japanese companies

I have been working in pharmaceutical industry quite long, and then moved (moved back) to one of the National University in Japan (actually in Kyoto) as Prof. SA (Specially Appointed) having concurrent Visiting Scholar appointment at a State University in California.

In late 2018, I decided to retire from both universities and came back to my home in Ichihara City in Chiba Prefecture, southeast from Tokyo. In hindsight, that was a nice timing since if I were to continue my work in California for some while longer, I should have had much difficulties in coming/traveling back to Japan because of the pandemic. Later-on, I heard that many of Japanese researchers there actually had much trouble and difficulties in renewal of their J1 visa status.

Upon my return to Chiba Prefecture, I established my independent consulting firm as CEO & CSO providing medical and pharmaceutical consultations to local Governments, industry, (public and private) educational entities and Anglican Communion church/educational activities.

Consequently, now I am a semi-retired independent consultant. "Semi-retired" means availabilities of enough time/days on audio and music enjoyments.

 

[Yems]

Thank you for your kind attention and interests on my time alignment measurements.

I can share various tone signals I prepared for the measurements, and the same for the contents/tracks in Sony Super Audio Check CD. I will PM you soon today or tomorrow.

As for the Sony Super Audio Check CD, you would please also refer to my post here for complete spectrum analysis by Adobe Audition 3.0.1 and MusicScope 2.1.0; in that post, you can also find the PDF booklet (liner notes) in English translated by myself.

dear dualazmak

at first i have to say that i'm overwhelmed by your kindness sharing all this! Thank you very much! I appreciate your scientific approach your knowledge and your perfectionist mindset. That's exactly the way i'd like to go. I'm 'infected' by the 'high quality audio virus' since the age of 12. Two years ago i updated my speakers to ones with active crossovers. A few weeks ago i started learning about measurment and optimizing parameters, crossovers, filters, but i'm still just 'scratching the surface' of it.
I will rebuild your audition files and try to tweak my settings as ideal as possible in the next days. It will be a pleasure and honour for me sharing my findings with you.

Best Regards
Yems

 

[gene_stl]

@Yems and @MarcosCh in my 55 or so years as an audiophile and almost 65 as an electronics hobbyist @dualazmak is the most scientific and objective audio hobbyist I have ever met. Of course, since he likes many of the same things I do, it is easy for me to like him. (ie. multi-amping and Yamaha Be speaker systems).

 

[dualazmak]

Not only the precision (0.1 msec level) time alignment over all the SP drivers but also SP facing directions and sound-deadening space behind the SPs plus behind our listening position would be critically important for effective (perfect?) disappearance of speakers

Hello friends,

I posted almost the same contents of this post in my post here on the remote thread entitled "What makes speakers ""disappear"" and can it be measured?".
I hope and believe that it would be allowed and worthwhile sharing them also here on this project thread.

For realization of effective (perfect?) disappearance of speakers, not only the precision (0.1 msec level) time alignment over all the SP drivers but also SP facing directions and sound-deadening space behind the SPs plus behind our listening position would be critically important.

As for the precision (0.1 msec level) time alignment over all the SP drivers, you would please refer to my summary post;
- Perfect (0.1 msec precision) time alignment of all the SP drivers greatly contributes to amazing disappearance of SPs, tightness and cleanliness of the sound, and superior 3D sound stage: #520

Now, you would please carefully look at photo of my SP physical arrangements;

The SP cabinets and drivers are not directed to my face sitting at listening position, but they are intentionally arranged in parallel with the side walls.

Furthermore, behind the wide plane between L&R SP drivers, we have open air space of our dining room; I believe this is critically important. Although you can see the sliding glass doors behind the main SP cabinet, the Yamaha NS-1000 cabinets are fully sealed ones with no rear bass-reflex ports. The large heavy sub-woofers, Yamaha YST-SW1000, have open ports in front not in rear.

Edit:
As for the unique position (under the main SP cabinet) of L&R super-tweeters Fostex T925A, please refer to my post here.

I also have fairly large open space (actually another room) behind my ears as you can see in this photo;

As I wrote in my post here, the rear room is a Japanese style tatami-mattress-floor room which is acoustically well "dead" and effectively minimizes the sound reflections and resonances. Of course, the sliding doors between the rooms are kept open during the listening sessions as shown in the above photo.

I often place sound absorption sponge mattress in front of the white wall and the opened glass door leading to the corridor;

As shared in my post here, I identified "that wall" causes very slight sound reflection and standing waves. Consequently, in the occasions of my really precise "measurements", including the SP transient characteristics/behavior measurements, I put further intensive insulation/deadening treatments to the wall as shown in this photo;

As also shared here, the ceiling of the listening room is covered by microporous diatom panels carefully selected with proper sound absorption performance. On the wooden floor, we have the large carpet also selected with suitable sound absorption properties.

For the subjective (and possibly objective?) assessments of "disappearance of speakers", it would be also important utilizing and listening to common/consistent "audio sampler music playlist" consists of excellent recording quality music tracks of our preference selected from various genres/categories. You may find an example of such "music sampler playlist" here and thereafter on this project thread which has been summarized here and here.

 

[dualazmak]

Revival of analog LP player (MC cartridge) in my DSP multichannel multi-driver multi-amplifier fully active stereo system for real time on-the-fly vinyl LP listening (and digital recording, if needed)

Hello friends,

Edit: Please also refer to my post;
- Summary of my motivations reviving vinyl TT (turntable) in DSP-based multichannel time-aligned multi-SP-driver multi-amplifier fully active stereo audio setup: #758

As briefly described in my post here, about 15 years ago I have digitized almost all of my around 300 LPs into 192 kHz (or 96 kHz, 44.1 kHz) AIFF format and taken the digitized LP tracks into my digital music library together with all of the other ripped CDs, SACDs (1 bit 2.8 MHz DSD layer), DVD Movies, download-purchased digital music tracks.

At that time, my procedure of LP into AIFF digital files was as follows;
- Properly clean-up/wash the LP,
- Connect the phono out of LP player DENON DP-57L to my Accuphase E-460's phono stage (actually AD-50 option phono card on E-460),
- Connect Pre-Out of Accuphase E-460 to my PC's Line-In with stereo RCA cable,
- Play LP by DP-57L with DENON DL-301II MC cartridge, (for proper search purpose, I should also write DL-301 Mark II, DL-301 II, DL-301 ii , DL-301 Mark ii)
- Digitally record the LP sound using software Audacity through PC's Realtek ADC chip (192 kHz 24 bit),
- Carefully remove, if needed, scratch and/or pop noises by Audacity,
- Divide the Audacity raw project file into each of the LP tracks,
- Export/save the digital tracks in PCM AIFF format into a special (LP digitalization) HDD/SSD folder,
- Add needed tags, almost manually by myself, to each of the AIFF digital files/tracks using JRiver MC's tag editing utilities,
- Add proper cover art in each of the tracks.

All of my vinyl LPs (LP tracks), therefore, have been already thus digitized and stored in my digital music library and they can be very flexibly searched/sorted/played just in the same manner for all the other ripped/downloaded digital tracks.

Consequently, as you may easily guess, nowadays I seldom use my treasure LP player DP-57L+DL-301II even though it is still in perfectly functioning shape; it has been being detached from my multichannel multi-amplifier system during the past several years. So far, my DP-57L received overhaul maintenance service twice by Denon Company in Japan.

https://www.denon.jp/ja-jp/museum/products/dp57l.html
https://www.denon.jp/ja-jp/museum/products/dl301ii.html

Edit to add on December 16, 2022
As shared in my post #696, even though the recommended needle pressure for DENON DL-301II (MC) is 1.4 g +/- 0.2 g, I always use it in 1.8 g which I determined through my intensive listening tests about 15 years ago. Accordingly, both of the Q-Damping and Anti-Skating dials are now set in 1.8 position.

Furthermore, many of my beloved LP albums were remastered from the original recorded tapes and re-released in CD and/or SACD formats. I purchased many of them and easily ripped them into my digital music library; in many cases, remastered digital CD release surpasses old LP release in sound quality as you may agree (even though I still keep all the digitized-by-myself LP tracks in the digital music library).


Well, BTW, a few weeks ago, I and my wife were invited to audio room of my audio enthu friend; he is "the jazz fanatic friend" using JBL 4344 driven by nice single stereo amplifier as I briefly touched in my post #438. We really enjoyed our wonderful and intensive jazz audio session; you may guess the jazz sound by JBL 4344.

He kindly played many CDs and LPs, and I was much impressed by the sound of "recently released" 45 rpm 30 cm HiFi jazz LPs which greatly encouraged me towards possible revival of my LP player DP-57L+DL-301II into my DSP multichannel multi-driver multi-amplifier fully active stereo system, especially for real-time play (and for HiRes digitization, if needed) of recently released HiFi LPs especially 45 rpm 30 cm ones (at present I have none).

If I would successfully re-install my DP-57L+DL-301II in my latest setup for real time listening, then he may bring several of his wonderful 45 rpm 30 cm jazz LPs to my home, and we will have wonderful comparative listening sessions with my multichannel multi-amplifier setup; it would be really an enjoyable session for both families, I believe, since in my setup we can apply very much flexible on-the-fly DSP control/tuning including the XO points and filters, the Fq gain adjustments over five SP drivers (per L and R), as well as the group delay controls. I promised him, therefore, that I will soon definitely realize on-the-fly real time listening of vinyl LPs in my DSP multichannel setup.

Now I cannot use, however, the fairly nice phono stage of Accuphase E-460 (option phono board AD-50) and the nice phono stage of Yamaha A-S3000 since they now directly drive midranges and woofers, respectively. Also I cannot use Yamaha A-S301's phono stage (only for MM cartridge) since A-S301 now directly drives super-tweeters.

These mean that I need one stand-alone stereo phono MM/MC preamp (phono MM/MC equalizer preamp), and one stand-alone acceptably-HiFi audio interface (ADC) for USB digital input into PC via dedicated ASIO route while playing LP by existing DP-57L+DL-301II (MC); this time I really hate using PC's on-board Realtek audio chip as ADC (hope you would agree in terms of sound quality).

From budget perspectives, I do not like to spend much extra money on this since I (we) will rarely utilize such on-the-fly real time play of vinyl LPs in my multichannel setup; in case if I would be seriously impressed by some of recent 45 rpm 30cm LPs, I will of course carefully digitize all the tracks into 192 kHz 24 bit AIFF format to be incorporated into my digital music library for possible daily repeated listening.

Very fortunately, as for stand-alone acceptably-HiFi audio interface (ADC), I already have one high-CP (high cost performance) TASCAM US-1x2HR as shared in my post #369 and thereafter;

https://tascam.jp/us/product/us-1x2hr/top
https://tascam.jp/us/product/us-1x2hr/spec
https://www.amazon.com/Tascam-Resolution-Versatile-Interface-US1X2HR/dp/B08MFN1JBD?ref_=ast_sto_dp

The specification, especially stereo Line-In and ADC (up to 192 kHz 24 bit), are just nice enough for my current purpose; I have already fully validated and utilized TASCAM US-1x2HR. You would please also find a nice review article on US-1x2HR;
https://higherhz.com/tascam-us-1x2hr-review/

Accordingly, I only need purchasing one stand-alone stereo phono MM/MC preamp with acceptable HiFi grade performances and of nice CP. After my intensive web surfing during the past week, I purchased one AUDIO-TECHNICA AT-PEQ30, a product of Japan domestic company.
https://www.amazon.com/Audio-Technica-ATPEQ30-AT-PEQ30-Phono-Equalizer/dp/B087Q8G4LX/ref=sr_1_2?crid=2CZNE7LVXOZ1J&keywords=AT-PEQ30&qid=1670593513&sprefix=at-peq30,aps,225&sr=8-2

You can also find nice review pages on AT-PEQ30 including rather intensive measurements;
https://www.soundstagenetwork.com/i...reamplifier-measurements&catid=414&Itemid=547
and
https://www.soundstageaccess.com/in...39-audio-technica-at-peq30-phono-preamplifier

In my DSP multichannel multi-amplifier audio system, I always use JRiver MC as my audio player as well as the master volume controller. For real time on-the-fly listening to LPs, therefore, I really would like continue using JRiver MC as control/play-back center with master volume control as well as mute/stop functions by mouse operation on PC monitor; the simple "mute/pause" of the sound signal would be indispensable especially during arm/cartridge down and up timings in real time on-the-fly LP listening. And, furthermore, I would like maintaining DSP EKIO's I/O routing unchanged for usual digital library listening and the coming on-the-fly LP listening.

For fulfilment of these demands, JRiver MC's "Open Live"-"ASIO Line-in" feature is just perfect since JRiver can digitally "hear" on-the-fly any of the ASIO input and can redirect it into the designated Audio Device (in my case into "ASIO4ALL" virtual audio device). Very fortunately, even during this "Open Live"-"ASIO Line-in" listening, JRiver MC's volume control, mute/pause function are fully active; using the audio interface TASCAM US-1x2HR, JRiver MC can hear the dedicated ASIO Line-in "US-HR Series ASIO" in up to 192 kHz which is the maximum bit rate for DSP EKIO. Consequently, I have no need of changing output audio device (ASIO4ALL), and the entire configurations including I/O routing of DSP EKIO can remain exactly unchanged.

In order to avoid any possible interference/intrusion via Window’s WASAPI or “direct sound” route, US-1x2HR should be “disabled” at “Windows - Control Panel - Sound - Playback (Output) Device” and also it should be “disabled” at “Windows - Control Panel - Sound - Recording Device”, so that US-1x2HR can be utilized only via ASIO I/O routing by JRiver MC.

Please note that I (we) can connect not only LP player but also any of (old?) "analog line level output only" audio device to US-1x2HR for on-the-fly listening with my multichannel multi-amplifier setup (and for digital recording, if needed). As for digital recording, I can use any of recording software which can digitally hear the US-HR ASIO Line-in, such as Audacity and Adobe Audition.

The total system diagram including my LP player is like this;

The monitoring of SP output levels by my DIY 12-VU-Meter Array remains unchanged;

The signal path including DSP EKIO configurations also remains unchanged including XO/EQ and time alignment (group delay) controls;

The "all in ASIO" I/O routing remains unchanged but having the new "UR-HR ASIO stereo line-in" from US-1x2HR;

Of course, my standard best tuned Fq response remains unchanged;

My tentative physical layout is like this; the stacking of DP-57L on top of ACCUPHSE E-460 has no heat/warm-up issue since E-460 is really cool amplifier and also there is enough space between the two;

The physical SP alignment and listening position remain unchanged;

After my successful initial tests of on-the-fly listening to LPs, I am on intensive comparative listening between on-the-fly listening to LP (using fully washed/cleaned-up LP) versus ripped CD listening for same HiFi recorded tracks, for example like these; the lowest pipe sound is 32 Hz with high Fq pipes singing together as I shared in my post #641 accompanying Fq spectrum of Adobe Audition;

I am much impressed by the excellence of the LP sound quality (originally digitally recorded by ARCHIV) and by the still amazing performance/traceability of DP-57L+DL301II together with the stunning transparencies of AT-PEQ30 and US-1x2HR; really nice revival of DP-57L+DL301II in my multichannel multi-amplifier setup, and my nostalgic enjoyment of the "ceremonies" for playing LPs.

I will soon inform "that" jazz enthu friend about the revival of on-the-fly listening to LPs in my setup inviting him again to my audio room together with his nice 45 rpm 30 cm jazz LPs.

Also, I would highly appreciate having your suggestions/recommendations on recently released HiFi 45 rpm 30 cm stereo LPs on classical music, if you know some.

Edit: Please also refer to my post;
- Summary of my motivations reviving vinyl TT (turntable) in DSP-based multichannel time-aligned multi-SP-driver multi-amplifier fully active stereo audio setup: #758

 

[Newman]

Revival of analog LP player (MC cartridge) in my DSP multichannel multi-driver multi-amplifier fully active stereo system for real time on-the-fly vinyl LP listening

It's not real time if it's DSP... strictly joking!

 

[Sal1950]

WOW, You must really enjoy all this ripping and tweakery of the various formats.
Sounds like you spend a huge amount of time on these investigative projects.
I initially did much of the same with 300 LP's before I sold them all but now find I'm preferring
to replace them with a factory digital remaster and many of them have been replaced by 5.1 releases or better.
Not a criticism, just a observation.
Whatever twists your wheels is cool, have fun
Sal1950

 

[MCH]

Very cool @dualazmak . Do you get much delay with your vinyl setup? I do stream my signal and get like 5-6 seconds delay, what at first was a bit weird but now I find very helpful to return to my couch, but I was wondering if there would be any noticeable delay at all with a wired setup like yours.
Enjoy the revival!

How to integrate your turntable/analog source in your streaming system - Step by step instructions for dummies

Hello all, I thought it would be good to put together some simple instructions to integrate a turntable, or any other analog source, into a 2022 wifi streaming environment. My own experinece tells me there are at least two reasons one would want or need to do this: 1. There is a tendency...

audiosciencereview.com

 

[dualazmak]

Do you get much delay with your vinyl setup?

No, not at all. There is no audible delay with vinyl LP play; it is really real time, on-the-fly, in my present setup.
This can be clearly confirmed when I look and hear the arm (cartridge) up and down in rather low sound volume.

 

[MAB]

Very cool @dualazmak . Do you get much delay with your vinyl setup? I do stream my signal and get like 5-6 seconds delay, what at first was a bit weird but now I find very helpful to return to my couch, but I was wondering if there would be any noticeable delay at all with a wired setup like yours.
Enjoy the revival!

How to integrate your turntable/analog source in your streaming system - Step by step instructions for dummies

Hello all, I thought it would be good to put together some simple instructions to integrate a turntable, or any other analog source, into a 2022 wifi streaming environment. My own experinece tells me there are at least two reasons one would want or need to do this: 1. There is a tendency...

audiosciencereview.com

I have a phono preamp plugged into the ADC of my DSP crossover. I have no delay. Like you said, my not be a problem but it would take some getting used to. I like the sound of the needle drop, but sitting down for the first track might be good too.

 

[dualazmak]

I like the sound of the needle drop, but sitting down for the first track might be good too.

My DENON DP-57L has well designed (oil damped?) automatic arm up-down system; of course the lift dumper goes down and does not touch on the arm during the LP play.
The lift height of the cartridge needle over the LP surface can be easily adjusted depending on the physical dimensions of the cartridge and the supporting shell; I set the lifting height in 5 mm between the needle of DL-301II and LP surface.

When I press the 33 rpm (or 45 rpm) play button, the LP disk starts rotating really smoothly (thanks to the direct servo motor) and the rpm speed is locked by the very accurate quartz system (the "LOCK" indicator will tell us), and the cartridge automatically goes down to the LP surface. The slow down movement is really smooth and nicely controlled, and the needle goes down the 5 mm height in about 3 second. My DP-57L is located at only 1.5 m away from my listening position, and I can easily move and sit on my listening sofa within that 3 second.

 

[dualazmak]

Hello friends,

I use cheap Numark PT01 portable TT (old version!) and its cheap arm+cartridge for my "final cleaning of LP tracks" by 78+10% = 86 rpm real tracing; usually I perform this real tracing clean-up three times before bringing the LP to my DP-57L+DL301II HiFi setup. Of course, each time I clean-up the PT-01's cartridge needle with a small fine brush and pure isopropyl alcohol;

 

[dualazmak]

Hello friends,

Even though the recommended needle pressure for DENON DL-301II (MC) is 1.4 g +/- 0.2 g, I always use it in 1.8 g which I determined through my intensive listening tests about 15 years ago. Accordingly, both of the Q-Damping and Anti-Skating dials are now set in 1.8 position.

 

[dualazmak]

Inside of Audio-Technica AT-PEQ30 phono preamplifier, and successful DIY suppression of inaudible EMF (electro-magnetic field) interference noise

Hello friends,

I am still in final fine tuning process for on-the-fly real time listening to LPs using DENON DP-57L + DL-301 II (MC) with AUDIO-TECHNICA AT-PEQ30 phono preamp and TASCAM US-1x2HR audio interface (ADC) in my multichannel multi-driver multi-amplifier fully active audio setup.

As for AT-PEQ30, I found that very faint, even inaudible at listening position, a little bit of EMF (electro-magnetic field) interference noises by AT-PEQ30 "itself": this low level low Fq noises can be seen in DSP EKIO's vertical VU meters when the master volume in JRiver MC is set to my maximum (-10 dB position) which would give "the unusual loudest sound" in my system of standard EKIO and amplifier gain settings. (Please note that my usual very high gain play of music is given by around -17 dB master volume position in JRiver MC.)

I fully confirmed that such inaudible EMF noise is given by AT-PEQ30 itself in MC cartridge mode; the noises remain unchanged when I disconnect the phono input plus ground cables from DP-57L player, the noises completely stop when I disconnect the RCA cables between AT-PEQ30 and US-1x2HR ADC (so US-1x2HR is free of such EMF interference), and the noise pattern depends on the physical location of AT-PEQ30, i.e. on the nature of EMF.

Consequently, I first changed the layout position of AT-PEQ30 + US-1x2HR from the top of Sony TA-A1ES to on the top of my narrow side cabinet which reduced the inaudible EMF noise level in about 4 dB;

I could still "see", however, residual low level inaudible (at my listening position) EMF interference noises in EKIO's vertical VU meters when I set the master volume to maximum (-10 dB position) in JRiver MC;

As you can observe in the diagram, the gain of such EMF noise (at maximum master volume) was around -42 dB, and it distributed mainly in super-low sub-woofer Fq range of 15 Hz - 50 Hz, and also much lower around -46 dB in woofer Fq range of 45 Hz - 600 Hz.

Then, I decided to open AT-PEQ30 expecting I could do some DIY EMF shielding inside it;

Many years ago, I have done successful/effective DIY suppression of EMF interference noises on my PCI audio interface card "within" my workstation PC using thin pure copper plate as EMF shield rapping the PCI audio card; of course I took careful electrical insulation avoiding any "short circuit" by the pure copper plate.

I did the same approach this time for AT-PEQ30 using 0.3 mm thickness pure copper plate, as shown in below photos; I "installed" 3D EMF shielding for AT-PEQ30 circuit board with the thin 0.3 mm pure copper plate; all was done inside the AT-PEQ30 box except for the large bottom copper plate.

As shown below, I could successfully further suppress the EMF interference low Fq noises in about 6 dB;

I hope and believe now I could have completed my fine tunings for on-the-fly real time listening to LPs in my multichannel DSP audio setup; even though I will rarely utilize it as I wrote on the top of my post #688.

 

[Holmz]

@dualazmak great work!
I would have been assuming it was the coil ringing at RF freqs, but you nailed it.

 

[dualazmak]

@dualazmak great work!
I would have been assuming it was the coil ringing at RF freqs, but you nailed it.

Thank you for your encouraging words.
I would be always happy if this kind of my finding and approach would be "worthwhile reference" for my friends in ASR Forum.

 

[Neddy]

Well done!
Your persistance, inventiveness, and creativity, and sheer knowlege - not to mention sheer determination - are so impressive!
You remind me of me 30 years ago - and still, today, almost nothing enters my house without be modified, improved, or customized in some fashion or another!
It's like a disease - seeking perfection? Hm. Adopt, adapt, improve!
Nice array of gear - esp since you thoroughly understand (and have analyzed) every device there, and no doubt put hours of time in to just thinking of where to place everything.
(Grin) No pics of the wiring behind it all??