My monitor/subwoofer system

(cont.)

Some skeptics may say that the real source for distortions could be the digital. I know that this is not the case. Ian (Madfloyd) has the same DAC, and even before the modifications addressing reduction of electronic noise that he applied to his unit it had sounded free of distortion in his room, which has a much more benign behavior than mine when it comes to lack of reflection-induced distortion.

I had thought it could be stress on the two-way speakers at high volumes. Yet experience with all improvements in room and system taught me each time that the speakers themselves turned out to be much more capable of low-distortion reproduction than I had anticipated. This in turn has made me more confident that I have not reached the limits yet of what the speakers inherently are capable of.

***

All these considerations aside, now for example the reproduction of Art Pepper + Eleven has lost so much harshness at high volume that I can now just enjoy the playing and great dynamics without much noticing any unpleasant side effects anymore.

What is obvious though is yet another improvement in timbre. Better timbre has always accompanied any improvements in acoustics and reduction in HF distortion, starting at the latest last summer with the move of the subwoofers from the front wall to their current position next to the speakers.

Art Pepper’s alto sax has a fuller tone, and the tone of the brass ensemble has yet taken another noticeable step from ‘traces of whitish’ to ‘all around golden’. While the transients on the alto sax are still sudden and hard, the ones on the brass ensemble are much softer and rounder, perhaps even more than before, a nice contrast. Yet another sign, as on many other recordings, that the system is not a one-trick pony when it comes to transients, but is able to give individual treatment to different instruments or instrument groups (and in general to different recordings).



Transient behavior has also changed on passages of Lee Morgan’s The Cooker. While Pepper Adams’ baritone sax towards the beginning on the opener “A Night in Tunesia”, correctly in my view, still sounds with hard transients at the starts of its brief circular figures, coming from the emphatic blowing into the instrument, the transients towards the beginning of the baritone sax solo around 3 minutes into “Lover Man” have changed. They were still relatively hard before, while in Ian’s system they had sounded much softer and rounder, as I found realistic on this type of music. Now they also sound softer in my system, even though not yet with the nice “buttery” tone that I hear in Ian’s system.

Overall, the change in sound by painting over the reflective surface of the shutters in the back of the room is very welcome. Yet another significant step forward. Now I know I should have done this way earlier. I looked up in my Amazon file that I had ordered the paint and brushes already in March this year. Yikes. What took me so long to do the job? I feel like an idiot. Well, better late than never!

I still have another change planned, this time for my ceiling. I will hopefully get to it within a few days.

Ron Resnick said:

Dear Al,

Thank you for this report! A big congratulations to you on your continuing sonic improvements!

I'm a little perplexed as to what you mean by "distortions"? Are you referring to an errant sound in the recording?

Something amiss in the microphone?

Some dial or a switch not set precisely correctly on the mastering board?

Do you mean what Mike Lavigne calls "high frequency hash"?

Do you mean unwanted treble energy due to high frequency reflections?

Thank you for helping me understand what you mean.

Click to expand...

Thank you, Ron! It sounds like harmonic distortion manifesting itself as harshness, with emphasis on upper midrange and treble frequencies. At its extreme it sounds like the speakers are slightly overdriven -- until with the next improvement it turns out they weren't.

If it sounds like unwanted treble energy is debatable. The sound is not bright, and has not been for a long while, but I do notice that the less problems there are with out-of-control reflections, the better the treble appears to be integrated. The sound also tends to be fuller, and more harmonically fleshed out, at the same level of treble energy.

In that sense, and considering the sum of all improvements in acoustics since, and including, the move of the subwoofers last summer, it sounds like a major gear upgrade, even though my last substantial one was the Octave HP 700 preamp more than two years ago. The only, still very worthwhile, upgrade after that was the reclocker between CD transport and DAC early last summer (also prior to the subwoofer move).

PeterA said:

interesting report Al. It seems amazing that this change caused such an audible difference. Good for you for figuring it out. How does cleaning up the mids and highs to this extent affect the quality of your bass reproduction?

also would you say painting the wood was more or less effective than the covers on the subwoofers?

Click to expand...

Thanks, Peter. I'm not sure if the bass quality has changed in this instance, but as you have heard yourself rather recently, the bass quality overall has improved substantially since October last year with the sum of all acoustic improvements since then.

The front covers on the subwoofers were less effective than the painting of the wood, but it may well be that the sum of putting the front covers on the subs *and* putting rubber blankets on top of their chassis, as I had done in the winter (with link to the report about that improvement provided above), was as effective.

Mandala wall tapestry above the listening seat (in the front of the picture) and behind the 10 ASC ceiling diffuser panels.



The wall tapestry cloth intentionally sags, see below explanation.

***

About two years ago I installed ASC ceiling diffusers in my room, which worked wonders for removing treble hardness and distortion, see posts on this page:

My Monitor/subwoofer system, page 9

My ceiling is inherently problematic; when you performed a hand clapping test, there would be a metallic 'zing' echo coming back from the ceiling. For an effort to further attenuate acoustic problems related to the ceiling, I was looking into options to address problematic reflections without causing more absorption; I did not want my acoustics to be any less lively. I did not want to spend serious money on elaborate diffuser panels, and at some point I remembered that Mike Lavigne once reported to have had installed cloth at strategic locations in his room. Looking at wall tapestries I discovered the mandala patterns seen in the above photos, and loved them. So I bought from Amazon for little money silver patterns for the front of my room, between ASC ceiling diffusers and system, and gold patterns for the back, to be hung at the height of the listening seat. I attached them to the ceiling with sturdy tape that is adhesive on both sides, which works very well. The cloth has hung from the wall for a few months now, without any sign that the tape would come loose (it seems now obvious that it never will). I deliberately hung the cloth in such a way that it sags; the idea was that sound reacting with the ceiling would have to diffuse twice through the cloth, separated from the ceiling by a small air cushion: once on its way to, a second time on its way from the ceiling. This would have more of an effect for high frequencies, but these were the ones I was most concerned about.

In my estimate the effect on the sound from the system is audible, with yet another slight reduction in treble distortion; I do think the effect is more pronounced from the cloth above the listening seat. The hand clapping test also suggests an improvement. It is now really hard to elicit any metallic 'zing' response from the ceiling, even with loud clapping. I don't notice any effect on the liveliness of the acoustics. Thanks, Mike, for the inspiration.

When Vlad visited last, he said he heard a metallic timbre on some material (which he said had not been there the previous time he visited). I did not hear it, but then, when I heard Ian's system the next time, in comparison it was obvious. I now heard a metallic tone on violin in my system that previously had always sounded rather wooden, with a silvery overtone in the high register (Rachel Barton Pine, Bach violin sonatas & partitas). That's in a way analogous to the frog boiling in water that only slowly gets hotter. You don't notice small changes, until they add up to something substantial, and then comes the sudden realization. I was thinking of changes that the system and acoustics could have gone through that might have caused this, and the only thing that I could think of at first was the change in electrical wiring from breaker box to wall outlet for the system from unshielded 12 AWG to shielded 10 AWG. Well, that would have been inconvenient if if had caused the change in timbre ... But then, I found it rather unlikely.

Another change was possible, one occurring over time that would have nothing to do with any changes induced by me. It was tubes. I calculated that my KT 150 power tubes could be around the 5000 hour mark, after three and a half years of extensive use. That would be around the usual expected life for power tubes (the small driver/preamp tubes are expected to last about 10,000 hours). So I grabbed two pairs of matched tubes that I had already in reserve, bought from Tube Depot, my trusted supplier over the years. Most of the break-in did not really take long, and the benefits were easily audible. The timbre on solo violin normalized again from metallic to the familiar wooden, rosiny timbre, depending on the recording. Piano also lost some metallic color that had not been there in earlier times. Distortion was quite obviously reduced. In fact, since in the meantime the system had gone through all those other beneficial changes, I now was presented with the most distortion-free sound so far from my system. Yet it would get even better...



A new KT 150 tube in my Octave RE 320 power amp, proudly displaying the trusted Tube Depot logo.

Finally, good power cords in my system!

ZenWave Audio: Power Cable Order (post October 16, 2021)

Follow-up (Post from today)

Two inches

Recently I decided to move my speakers two inches further apart. It was in a period where a mix of still high humidity and lower outside temperature caused the system to sound just ever so slightly bright even with the speakers fully toed out. Moving the speakers apart might make the sound a bit less bright since the direct beam from the tweeters is even farther removed from the listener's ears, and that was indeed the result.

In the past, any move of the speakers further away from the sidewalls resulted in less distortion, so I feared that moving them apart, closer to the sidewalls, once again would increase distortion. The opposite was the case -- there was now less perceived distortion! Yet in the meantime the system and acoustics had undergone many changes from more than a year ago, when I fixed my speaker position until this recent move. It turns out when you change things, it is always good to revisit other variables. That is part of what makes this hobby so complex, but potentially also rewarding.

The silkiness of massed violins, so much improved by the ZenWave power cords, increased even further, and residual hardness on some loud passages receded.

Obviously, the soundstage got a bit wider as you would expect. But more than that, while soundstage space opened up a bit, perceived acoustic space opened up dramatically by this small move. Hall ambience is more pronounced. Separation of instruments increased quite substantially. On orchestral textures, buried inner voices now at once became audible. Intelligibility of music increased. For example, on Lee Morgan's 'Lover Man' (from the album 'The Cooker') the stand-up bass notes alongside the initial trumpet solo were more articulate and much easier to follow with speakers a bit further apart.

This effect was easily reproducible. The initial speaker move one inch each for a total of two inches could simply be done by shuffling the monitors on the speaker stands, and this was of course easily reversible for checking sound differences. Only once I was satisfied that the new position was the desired improvement, I proceeded to the harder task of removing the heavy monitors (70 pounds) from their stands, moving the 100 pound stands from the concrete plates they stand on, re-adjusting the position of the plates, and putting stands and speakers back. The result is shown in the above image: previously the concrete plates for the monitor stands had been snug adjacent to the ones for the subwoofers. The distance from tweeter to tweeter is now 7 feet 8 inches.

In the meantime acoustics again have changed in a weather-related fashion, and my speakers are once more very slightly toed in, at the new position.

MadFloyd said:

I heard Al's system last night - first time in weeks - no, probably more like months?

I guess his recent speaker adjustment is part of the difference I heard but there's no doubt in my mind that the biggest change came from the power cords. I'm used to hearing some grain (distortion) in Al's system. Frankly I attributed this to his electronics (or the fact that they used tubes). But what I heard last night was super clean - more like I would experience from good solid state - but with the benefits of tubes. I was VERY impressed. Definitely the best I've heard his system sound in terms of getting out of the way and not imparting artifacts on the sound.

Al played a Hadyn symphony (Neville Marriner/Academy of St Martin in the Fields) and the strings sounded sublime (as did the woodwinds!). Not euphonic, not pumped up with tube harmonics, not grainy, just beautiful, pure and natural sounding. Today I watched the Boston Symphony Orchestra rehearse some Mozart. The strings were also sublime. Hearing them did not change my opinion of what I heard last night.

Good on Al and ZenWave.

Click to expand...

Wow, that's quite a compliment, Ian!

You're right, most of the improvement comes from DaveC's power cords. It's astounding just how much better electricity can clean up the sound and allow it to exhibit better resolution. I have been inspired by our recent power cord comparisons in your system, and also, on the technical side, by Billinge's post here:

https://www.whatsbestforum.com/thre...cables-in-your-walls.29938/page-6#post-741196

and his follow-up:

https://www.whatsbestforum.com/thre...cables-in-your-walls.29938/page-8#post-742134


In terms of fine-structured silky texture I do think that reproduced orchestral strings can come surprisingly close to the real thing, be it on analog or digital. In terms of richness and depth of tone, I'm not so sure. But that also depends on the hall acoustics, and where you sit in the hall. I have heard a richness of string tone live that is far beyond anything reproduced (at least as I have heard it), and there is live string tone where reproduced sound compares more favorably.

I look forward to more shared listening sessions at either of our places. They are always fun!

Another move of 2.5 inches -- but not more

From the new position of the speakers (post Nov 11, 2021) I could easily establish, by once more shuffling the monitors on the speaker stands outwards, what would happen if I moved the speakers yet further apart, at 1 inch or slightly more for each speaker.

As in the previous move of the speakers, there were again:

• a little bit wider soundstage
• an opening up of acoustic space
• a cleaner sound with yet less distortion
• better separation of instruments
• better bass definition

A slight flattening of tone and reduction of perceived dynamics, with the speakers moved further apart, could be remedied by a minor increase of toe-in.

After I established all those improvements, I once again proceeded to removing the heavy monitors from their stands, moving the stands from the concrete plates they stand on, re-adjusting the position of the plates, and putting stands and speakers back. The result is seen in the above image (the toe-in is not visible with the angle the camera produces).

Following this, I tried what happens if I moved the speakers yet further apart. This did not work well. There now was somewhat of a loss of musical energy that I did not like, even with extra toe-in above what I already had. I may revisit this some time, because comparisons were not exhaustive, but what I heard so far was not promising.

In the image you will also notice a desk lamp above the preamp, which I recently acquired. It's this one:

YOUKOYI Desk Lamp

I love it. It adjustably shines in three colors, ranging from silver white to a brownish warm glow. I chose the latter. The lamp can also be dimmed. It's touch on/off, no switch. It is very useful in my setup for accurately setting the volume on the preamp, and for shining a light on the tray of the CD transport.

About two months ago (I forgot to mention it earlier) I also tightened the 8 soft brass screws on the Reflector mid-woofer. Since I often play loudly, they had, as I would have expected, loosened just slightly over the almost 4 years time that by now I have had the speakers. I had been apprehensive about tightening the screws, but it was very easy to do, without any slippage of the screw driver. The tightening needed on all of the screws was consistent, between 1/8 or 1/4 (hard to tell) of a turn on all screws of both speakers. Obviously I was careful not to over-tighten anything; the resistance felt was an easy and safe guide.

Adjusting phase on the subwoofers: Better mid-bass

Upon Peter A.’s last visit, we played Kenny Burrell’s “Midnight Blue”. Peter commented that there was quite a bit of bass in the reproduction of this recording on my system.


I then decided to demonstrate at the beginning of track 1, ”Chitlins Con Carne” (see above), how much of the bass came from the monitors alone, so I turned off the subs (easily done by a switch on the preamp that decides about the outputs). To both our surprise there was more bass without the subs! Repeated switching back and forth between the outputs confirmed the effect beyond a doubt.

This was weird. I had noticed before that on one track of Miles Davis’ "Kind of Blue" there was cancellation of the bass by the subwoofers, but I had not spent much thought on that, also because the cancellation effect there was actually positive (removal of bloating of one bass note by an apparent room node).

When in January 2018 I was about to make a decision on which subwoofers to purchase, Ian (Madfloyd) strongly recommended to me that I should buy JL Audio subwoofers, because of their high adjustability, which goes considerably beyond what many other subs had to offer, including my old REL Storm III. He had experience with bass cancellations, especially when it came to employment of two subwoofers (a single sub was less critical in his experience). I am very happy that I followed his great advice. This is not just because of the adjustability – the E.L.F. (extreme low frequency) attenuation was a lifesaver in my medium-sized room – but simply because of the great sound, enabled by the sheer speed and agility of the reaction of the subs to the music. Ian had highlighted the latter in his recommendation as well.

The continuous phase adjustment, which is also offered on the JL Audio subs, would in Ian’s opinion be useful to attack bass cancellations. I had tried it once before, but only one a single track, and could not hear a meaningful difference. Yet given the new experience, I decided to explore the cancellation phenomenon further. So the day after Peter’s visit I went to work.

I started with the ”Chitlins Con Carne” track on the Kenny Burrell album. Turning up the phase on one sub from 0 degrees to 45 degrees and beyond did dramatically change the amount of bass heard on the track! I couldn’t believe it. Then I tried what happened if I would increase the phase on both subs. That also worked. After checking some more music, finally I settled on 45 degrees phase on both subs, because going higher either didn't lead to further improvement or actually led to bloating of bass.

At the same time I received my ZenWave Clear Bass power cables for the system from DaveC, including for the subwoofers. These improved the situation even further, because while now I had much more midbass than before at the same volume setting of the subs, the bass control improved with the new power cables.

I was simply delighted about the amount of mid-bass, which was new to my system and further filled the mid-bass hole between the monitors and the deep bass of the subs, a hole that had already gotten much smaller over the years than it used to be in the beginning, especially with my old monitor/subwoofer system.

Yet more critical listening revealed that there was still some bloating at certain frequencies, and I decided to explore further refinement of the phase adjustment.

As I said, moving the phase knob further, to 60 degrees or beyond, did not result in an improvement, to the contrary. So I decided to further explore the phase space between 0 and 45 degrees. I moved the dial in smaller increments on both subwoofers, and listened to the character (not just the amount) of the bass on the Kenny Burrell ”Chitlins Con Carne” track. At a phase angle around 35 degrees on both subs the character with and without subs seemed to align best, with of course the subwoofers adding extra weight. I then listened to other tracks, where a lot of the bloat on certain frequencies was gone. On “Love Ain’t For Keeping” on Who’s Next by The Who there had been almost something like a mid-bass ‘hum’ throughout the opening lines at a phase angle of 45 degrees. Now it was gone.


On Pink Floyd’s “Echoes” (from “Meddle”) the bass guitar plays long notes, starting around 1:30. Both at 0 and 45 degrees phase some of the notes had a bloat almost as if they were ‘hanging through’, and when the voices begin around a minute later, the bass guitar lines were almost unintelligible. Now the notes seemed ‘straight’, and the bass melody around the vocal lines could be better distinguished.

What is more, I could now, on any material, turn up the volume of the subs considerably higher than before, without incurring a penalty of bloating. So I got a bit enthusiastic and decided on a volume where I had very robust bass. Yet when Ian visited a day after I made the adjustment, he thought the bass was too prominent, and too much tilted towards low bass compared to mid-bass. So I set the subs for the listening session in a relatively large step to a lower volume, too low as I later decided.

Of course, Ian was right about the too prominent bass at the volume that I had set initially. The lower volume that I then arrived at was not right either, and I decided to explore the issue with more deliberate fine-tuning in the days following. It turned out that the right amount of bass was critically dependent on very subtle changes on the dial. If you take the knob and say, horizontal is 9 o’clock and vertical is 12 o’clock, then changes that seemed to decided about just too little, the right amount, and just too much were made by dialing in the 5-minute range – or even the 2-3 minute range (such minimal shifts were barely controllable by just slight movement of the small knob by the fingers).

At first I settled on a volume that was a bit below the too black bass that I had when Ian visited, but still produced very robust bass, with meaty drum sound. In the process I found that the best for my room and set-up was also to set the E.L.F. (extreme low frequency) attenuation to maximum (about 14 dB down at 24 Hz) from about 12 dB down at 24 Hz.

I enjoyed the new volume setting for a few days and checked a diversity of material critically, including solo cello. While the low register of the cello was generous, I still found it within the range of believability. Yet then I found that some bass lines by John Patitucci on the excellent Chick Corea Akoustic Band live album (2018) were too dark and congested. Critical evaluation of more music revealed that, while solo cello had sounded fine, the cello in some string quartet recordings was too dark and black as well, with a hint of exaggerated bloom. This was a no-no. So I decided to turn the volume down yet again just a tiny bit, in a very small increment as described above. This seemed to do the trick, and extensive listening on yet again a large variety of material confirmed my satisfaction with the new volume setting. Cello in string quartet now sounded natural. Solo cello still had a robust low register, but without extra thickness (it sounds very good on just the monitors, without subs, as well). Bass lines on stand-up and electric bass cleared up, and while drum sound did not have the extreme saturation anymore that I had become used to, it still had good weight.

During the adjustments, one reference point was the bass and drum sound on Pink Floyd’s “Dark Side of the Moon” (DSotM), and I was now very happy with the final compromise that I had settled on. The mid-bass on Pink Floyd’s “Animals” was really robust, and the saturated mid-bass on “The Wall” was enormously satisfying to my ears (with slight caveats that will be discussed below in another report on further improvement).

The final changes from my old subwoofer settings were (see above picture):

• Going from a phase angle of 0 degrees to about 35 degrees
• Changing the E.L.F attenuation from 12 dB down at 24 Hz to maximum of about 14 dB
• Subwoofer volume slightly higher than before
• Low-pass frequency at about 60 Hz instead of 80 Hz (doesn’t make much difference actually); filter slope unchanged at 12 dB/octave

Conclusion of the story from above:

A while ago I had moved the main speakers further apart from each other, leaving a gap of about 2 inches between the concrete platforms on which the speakers stand and the concrete platforms on which the subwoofers rest. I decided that I wanted to get the subwoofers further apart and closer again to the speakers as well. Trying to lift the unwieldy 100 pound subwoofers alone is not advised. I could have waited for an opportunity for someone to help me with a move, but I decided that it should be possible that I could move the subwoofers over such a short distance across the carpet myself. Trying to push the heavy subs on their heavy concrete platforms was futile, but pulling the platforms with subs on them towards me, with my arms reaching out from behind the speaker stands, turned out to be suprisingly easy. Now the concrete platforms of monitor and subwoofer on each side are flush with each other again.

The subwoofer move yielded an even more improved sound. Bass was breathing a bit more, trading some congestion for more roundness, and there was yet more definition. For example, I could now easily follow Roger Water’s bass guitar in “Any Colour You Like” from Pink Floyd’s DSotM all the way through.

During a recent listening session at my place Ian seemed more satisfied with the bass that I have now. He also brought his spectacular Focal Stellia headphones, which he uses with his portable digital player. These $ 3K headphones are by a large margin the best I have ever heard, far better than the Stax electrostats in my first, headphone based, system 30 years ago (no, I have not heard uber headphones in the $ 10K range). They also have real bass, with punch and weight, and I was quite happy to hear that my new speaker bass favorably compared with the headphone bass in terms of linearity and character, for example on Pink Floyd’s “Breathe” (DSotM). Of course, speaker bass can never be quite as linear due to room interactions, but to my ears it was satisfyingly close. I also had wondered if the long bass notes on Pink Floyd’s “Echoes” were still a bit too dark and “deep” sounding on my system (on my cheap headphones playing the YouTube video on computer the bass sounds much lighter, even though very well defined), but I was pleasantly surprised that the bass guitar sounded just as black on the Focal Stellia headphones. It was quite close in overall character.