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Playback Listening
Topic: What makes goosebumps?

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Posted by rowuk on 02-09-2020
I am in the think through stage of improving my playback. Each loudspeaker currently has 2x 12" woofers in a sealed 80 liter cabinet (Fc-500 Hz). Measured LF extension is more or less flat to 30-35 Hz.  Efficiency is close to 100dB/watt. The listening room is about 20 square meters large.

When listening, the presentation is currently large with lots of "space" and "depth". Comparing my feelings with live concerts, there is a certain amount of "tactile" sensation missing - even in classical music (my most listened to genre). I am not talking about slam. Even live chamber music with no real LF at all has this parameter. A solo lute or voice can show this. There is a certain amount of sensation currently there (more than most systems that I have heard elsewhere), just not as much as I would like. I listen to a lot of my playback at very much live levels (especially chamber music). I have experimented extensively with equalization, various subwoofers, relocating the speakers. I can get more bass, but not that "tactile" feeling.

Has anyone experimented with tactile perception in audio (not shakin yer booty...).

I am not looking for a recipe or recommendations for new hardware. I am more interested where it comes from and how to manipulate it.

Posted by Romy the Cat on 02-09-2020
Good question, rowuk, particularly by the fact that you are looking a way not how to get it but to understand the ways to get there. Also, I am very glad that you are not taking about “slam music” but about, where good bass certainly shine but about chamber music where in my view good bass shine much more.

Before I would lay out my recommendations, I would like to name a few obvious factors.  None of the loudspeakers with woofers would do good bass unless you are incredibly lucky. Your main loudspeakers should very specific and very deliberate poison in your listening room with precision of centimeter or less and it is VERY unlikely that it would be the best position for bass. If might be but then it would be one of 10000s installations what it happens. Among all playbacks that I ever hears I remember only one when it happens and BTW completely accidently. So, when we are taking about better bass then we are taking about a dedicated pair of LF or ULF sections, separately powered and separately located in your room. How to powered and what the topology of the ULF section is very separate and complicated subject, let keep it out of the conversation for now. We presume that you have your good full range speaker and your good LF sections. You said that you have experimented with various subwoofers. Let presume that your failed were not by the quality of your specific implementation. So, basically you were trying to do it to pressurize your room with more LF output abut it did not look give you satisfaction of "tactile" sensation. Well, if you measure the bass responds in a concert whole in a reasonable seat then you would hardly het -3dB at 60Hz and well about 100Hz when a chamber music is being played in a concert whole.

Do an experiment.  Get any digital processor, switch your system in mono to connect your ONE dedicated LF section with 10ms delay crossed at 30Hz and another LF section with 50ms delay crossed at 20Hz.  You will not get your "tactile" sensation but you will get MUCH better bass it despite that most like if will be verlanized by your digital processor. So, what you effectively be dos is creating a longer reverberation time in your 20 square meters listening room. In your room you have RT60 (now long sound decades for 60dB) probably 0.2-03 seconds. In a reasonable concert hall you will get 2-5 seconds and some of them longer. This is very much changing how the perceive not only bass but the sound in entirety.

When you will be doing the experiments with LF delay try two tests. Play a good fast, loud and “aggressive” chamber music (I typically go for Third movement of Brahms Quintet for Piano in F minor). Crank your volume until you feel it become uncomfortable. Note the volume level.  Then connect your LF section with no delays. Do the same volume test. Your “uncomfort level” will go up for 1-2dB. Now introduce the delay. Your “uncomfort level” will go up for 10dB at least. Make the very same experiment with a good full range recording of a good harpsicord playing. Besides the “uncomfort level” experiment pays attention how ugly and abrasive harpsicord sounds at your only main speakers or with LF sections and how lash and magical it become with the delays. I typically for those experiments used a Colombia player Rafael Puyana. He was very well Recorded on Mercury and his play of Antonio Soler is stanning. The Soler died 300 years ago but it sounds very contemporary.

So, if you decide to yourself that what you were missing is longer decay in your room then let me know and I will pitch some directions to capitalize over this finding. If you feel that the chaise for longer decay did not bring you closer to what you are looking then let me know, preferably with more subjective adjectives what you do feel and we can go from there.

Posted by Paul S on 02-09-2020
Robin, your explication already includes a great sense of where you are and what you are after, and this should save you a lot of time. I like Romy's ideas as time savers, as well. On the hardware front, given what you say you are looking for, I think it takes 15", or more likely 18", drivers to have the sort of "effortless" "LF" you are talking about. At this time there may be smaller drivers that can produce this sort of "bass", but I haven't heard them yet. I have heard multiple-15", pro-ish set-ups that are pretty good with most music. Also, it's weird how a (U)LF driver that's billed as "103 dB efficient" might require 500 watts to "loosen up", in terms of the sound it delivers. I certainly agree that is requires luck to get that sort of LF from a typical, left/right ,"full range" pair of speakers. If to do this, I think it would take 5-way speakers, and they would be very big, also multi-amped. I like my room well-charged by horns, so Wagner sounds like it's coming from Heaven (or Hell). And as we try to go deeper, the room becomes at least an equal consideration, even if it's only a "sense of the room", since our listening rooms are (obviously) smaller than concert halls or cathedrals.

Best regards,
Paul S

Posted by rowuk on 02-09-2020
Paul, as this sensation also happens during performances without "bass pressure" (a solo lute or voice for instance), I am not even sure how to start looking. There is a part of real sound transmitted not processed by the ears, rather over the skin. Romy has given me some things to think about and try. I am having an operation this week and will not be able to play trumpet for a while, so this should keep me occupied with something challenging.
I have a couple of decent 15" drivers that I could experiment with. I have a door to my office in the listening room. I could turn it into an infinite baffle manifold and try Romys stuff as well - easy to change back. I am not sure that it has anything to do with "bass", I just know of no mechanism to make higher frequencies "tactile".

Posted by Paul S on 02-09-2020
Understood, and part of the reason I keep putting it in quotes. But much of hi-fi is "as if", isn't it? Getting back to harpsichord, for instance, it is amazing how noisy the instruments themselves are, yet one seldom hears/senses that via recordings. I think there are many "aspects"" of the sound of Music that are typically missed or they are glossed over by hi-fi. It has been noted on these pages that it sounds best to widen the frequency extremes, high and low, at the same time, as qualitative improvements to each seems to make the other more "natural". I don't really "understand" this, but I say, whatever "works". Again, you know what you're listening for, or you will know it when you hear it. I't's not so much "pressure" in this case as it is a sort of "foundation" that provides a "backdrop" that allows other things to become more plain. I noticed this years ago when listening to Debussy's La Mer with my big amps: the roiling orchestra became a chorus of voices with different textures. I love textures, and pretty sure I sense them with my skin. too; certainly I feel and/or react to them that way.

Best regards,
Paul S

Posted by rowuk on 02-10-2020
We refer to playback singularly as an audio event as we have recorded sound waves with acoustic devices (microphones) and play them back through other acoustic devices (speakers/headphones). The basic rules of stereo are generally adhered to (phase and intensity). With a bit of „imagination“, our head can reconstruct events and we derive pleasure from this. I had a concert this past weekend and was sitting on stage during a part where I wasn‘t playing. It was only the solo violin in Danse Macabre and I could swear that something was touching my face/cheeks in time with the music. It was a textured sensation. Something I have never before thought about. It kept coming back during the concert, sometimes just fleeting moments, sometimes extended. Generally it never was noticable when the orchestra was creating pressure. Maybe calling it bass is wrong although it was during the dissonant playing which does create low frequency resultant tones...
The thought is whether this is something that can even be recorded and played back. It was still there when I closed my eyes on stage and it wasn‘t the air conditioning. My playback has „tone“ and LF events also generate a pressure wave that moves my body (at least when the doors in the listening room are closed). This is something much more subtle however. I haven‘t ever read anything about it and thought that I would ask. Playback as a non-auditory event fascinates me. I will have some time on my hands and will try and see if the effect can be created when just reading the score - with no audio. Then score and ULF, then playback with Romys suggestions.

Posted by Romy the Cat on 02-10-2020

Rowuk, first of all, I very much recommend you do not undertake the Paul’s advice and do not go for any implementation of bass with bigger drivers or more driver of different topology of bass section like OB and so on. For sure better bass would make some improvement in your playback but the whole idea of mine regarding “sensible audio” is the improvement should address only understood listenable objectives. I very much feel, that we need to understand our very specific listening objective, formulate what is right with sound and what is wrong, to conceptualize what the solution should do and then go for targeted change in playback to aim your very much formulated sonic objectives.

You just made a very good post with a lot of information for discussion exposed. I agree that calling it bass was wrong as I do not think that your problem with bass. However, my recommendation how to explore bass was very correct and if bass is something that you want to explore then it is the only direction to go. I do inset that without understanding how reverberation time impact the perceived recorded music it is impossible to formulate you ourselves what is proper audio bass. It has nothing to do with creating pressure and if you did not experiment with delay channels you would hardly understand what I am talking when I imply that proper bass should be impersonating prolonging delay. This is very different way to look into the bass and it is very different and quite complicated subject.

I think when you are taking about “textured sensation” is not bass but rather what I call “remote transient” characteristics.  The “remote transient” is not the same as transient as it deals how the transient are delegated to listening position. I understand why you have a feeling that it has to do with bass, because it is very noticeable during transients presented over bass passages, when bass notes act like a pedal point, “softening the air” and the transients direct scratch the soil. I need to say that transients is not right phrase but we have no better. I have the word in Russian language but it has no translation in English. The best I would translate it is English would be “instantaneous rise of subtilization among rarefaction”. I do not know a good English word that would express all of it. However, I can give you a tool to experiment with it yourself and to figure out if it is what you are looking for.

I do not know what speaker and amplifier you have. Let pretend that it is a speaker that does not use multi-amping and SET amplifier. You can do the same with any other topology but it is very easy with SET and mult-tap output transformer. Let pretend that you have 4, 8 and 16 Ohm output taps at your output transformer and you currently connected at 8R. Listen carefully and pay attention to speed of transients, dynamic contrast and speed of decays. Now connect you speaker to 16R tap. You will detect that transients become faster, dynamic contrast more aggressive and the decays will be much sooner. Let forget the explanation that harmonic distortions envelope was changed and what role the second harmonics play in it. We do not care about technical explanation now but purely focused on our listening perception. You will lose the volume of you sound twice but you should be able to compensate it with you preamp, hopefully it works the same with different gain levels, not all of them do. Now is the time to switch to 4R tap. You will have more volume and much more lethargic sound with very round transients. Do make a mental notes that the decays become very long and very “syrupy” and you most likely not going to like it BUT if you will be able to have the decays like 4R tap but the transients like  16R tap then you might feel that you into something. Now, pretend you have 32 Ohm output tap. Connect you speaker and you will have spectacular transients, almost like with live sound but you will also acknowledge that the sound with decal like this does not exes in nature as it will be literally fractured by fundamentals.

So, now you know that that you would like to have a speaker that would produce the transients like 64 Ohm output tap but the decay like 2 Ohm output tap, good luck with your search. BTW, experimenting with all of it in my past I made up the idea of multi-channel system with individual channel is driven by DSET specifically optimized to hack the transients/decay conflict. I do not offer you as solution but rather I offer you that experiment as an exploration tool if you get closer to where you would like to be in term of hear sound. To do the experiment requires a lot of extrapolation and interpretive targeting listening. Getting more ““instantaneous rise of subtilization among rarefaction” does not mean to get better sound overall but if you properly do your targeting listening then it will give you a sense if you are moving to a right direction in your assessment.

Another very important factor to consider. Different speakers have different capacity to handle that loading abuse. Some of them you change lodging twice and they completely collapse. Some of then you can load then 4-8 times more and less and they still hold sound integrity. Generally the softer suspension on speakers the best they care the loading abuse, with leather suspension probably the best. I have seen some absolutely unique speakers that can throw stunning transients with spectacular long decays. I have seen once in my life a little speaker driven with SET (both of them very expensive and I have my reasons do not reveal the name) when I was staying in front of the speaker with my eyes closed I was not able to say if it was life or recorded sound. I was not able to say it what I was listening it from another room, it was the only time in my life. So, the solutions are out there, we just need to look in proposer direction.

Rowuk, good with your operation. Hang around here, there is a lot of beauty in this world yet to consume….

Posted by rowuk on 02-10-2020
Well, I do have 3 channels of DSEP. Dedicated Single Ended Pentode: 
one channel (bass/mid 30-500 Hz) with a 307A DH pentode feeding two wonderful Fane neodymium Colossus 12" - one from FS to 150 Hz and the second from FS to 500 Hz. OPT with a lot of inductance wound for me by the german company Ritter.
one channel EL84 as a SEP (upper mid lower HF around 600 to 11K) feeding a 300 Hz tractrix horn and a Faital 1 ¼" neodymium driver with plastic (Ketone) diaphragm. OPT found by accident from a german company TRT.
one channel EL84 as SET with a Sowter OPT for tweeters (the one at the bottom driving a pair of planar tweeters
2 of the OPTs have 4/8 and16 ohm output taps. The tweeter OPT has 8 and 16 ohm.

All passive 6dB crossovers built into the amplifiers. I have gain controls on the Mid anf HF power amplifiers. All channels are time aligned and in phase. Preamp is a Pass B1 with low impedance output so driving the crossovers is no problem.

ULF is on my list of things to get to, but what I have is VERY tolerable, so I am not in a hurry. Add to that the challenge of ULF in a small room...

As I mentioned, I have some Fane 15" speakers from another project that could be used to investigate ULF as you mentioned.

I did play with loading 3 or 4 years ago. The 16 ohm tap was too "in my face" at that time but there were a lot of other unresolved issues. No hardware has changed in my system for the last 2 years. The sound "fits" and even although there are things that could probably be better, I have not been motivated to define what the solution for them could be - until this past weekend...

Posted by Romy the Cat on 02-10-2020
Ok, you did experiment with loading and found that make you MF to idle more sound to was too "in your face". It is fare but was it delivering better "tactile" sensations. You understand that less loading of one of your channels should make you to lower output from other channels in order to equalize the volume level. It might also in many instances to make your bottom overlap to be more aggressive. It means the if you cross you MF at let sat 500Hz and then you load the MF less then you might rise your crossover to 700-800Hz in order to let the lover MF to be care by your lower channel more. It will all depends from the drivers and many other things. Anyhow, I wonder if that sense of "tactile" sensations in your estimation was different when you experimented with loading.

There is another subset. The non-auditory events that you mentioned before is the thing and there ARE some people, I know who have some experiments in this direction. I would like to keep it out of frame for now. Here is the question: You told that until recently you did not feel a need or frustration to make any change. What happened recently with you besides the obvious time out due to medial leave? Were any other aspects of your perception that you feel were altered recently. What I am trying to say there is an expression of playback and there is an expression of a listener. Was your town having a major electricity change? I know in Europe there is a lot of electrical heating and as the temperature dropped the electrical utility companies begin to drive the generators at higher load, thus more distortions… I am just fishing…

Posted by rowuk on 02-10-2020
The "tactile sensation" was during a live concert (multiple times) last weekend and reminded me of similar situations at other concerts. I had never thought about this effect for my playback and just decided that I would investigate it. 
As far as my "mind goes", I have not been operated on yet - but this was my last performance before the operation. I still have a couple of days of work left. No fight with my wife or boss, the same wine. There is nothing else that I would call special except that it was the last concert (the problem was an accident in an orchestra, someone in November moved their chair in a dress rehearsal back into my trumpet, bent the bell of the trumpet and knocked my 4 bottom front teeth loose. I played my December and January concerts with those loose teeth. There was some joy in getting through. There will be some jaw reconstruction and implants). Normally I am very concentrated while playing but the effect was very noticable/distracting. 
I came home and listened to various recordings in search of a similar tactile, but have no recollection ever having had the effect at home.
My son recorded the concert (he is an audio engineer) and I will get the raw digital source and see if he captured it. I know what measures made the effect. Of course, his microphones have a different perspective than my chair in the trumpet section.

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