Are you listening to your room or speakers?

[Scroobius]

Maybe some of you have read about the travails I had getting to the system I have now.  Well, not really travails, more an interesting, but at times painful, journey. BUT actually I am very very happy with how my system sounds. BUT - surely there should not be a BUT. BUT there is a BUT and there always will be a BUT for us hi-fi addicts (I am seeking help ha ha).

Anyway one of my absolute all time hero drummers is Tony Allen. The man is a total genius - he is four drummers rolled into one. Anyway that is not the point. The point is that I heard him on my friends system which is OK but not great - Musical Fidelity kit feeding PMC transmission line speakers. But I do have to say Tony Allen sounded absolutely great and really highlighted to me how lean my system is in the upper bass region. That set the worm turning. What if I had transmission line speakers? how would that sound in my room?

I have to say at this stage that my room acoustically is bad - very very bad!!!! - you would not choose my room if you did not have to!!!. It is the kiss of death to most speakers. It is "L" shaped with the speakers firing down the long part of the L and the short part (kitchen) of the L to one side of left hand speaker. Not at all symmetrical acoustically. To make it worse the long part of the L is a long thin room - really bad for acoustics. I used to have big transmission line speakers (that particular pair just sounded awful) and before them a pair of Quad ESL - they used to sound great in my old house (taking into considerations the limitations of Quads in the dynamics and bass department) but in my current room they sounded just plain awful. So I have to be pleased that the sound I now get is quite good.

But the question I had in my mind was what would the PMC transmission line speakers sound like in my room? Well I persuaded my mate to bring them down for a trial last Friday. So we set them up - and what did they sound like? well firstly on the end of NOS1USB and gainclones much more detail etc than on the end of their usual electronics. BUT they completely lost their attractive bass quality in my room and sounded light in the upper bass in just the same way that my speakers do. In fact in large measure they took on the character of my AN speakers except for a notable lack of dynamics and resolution. 

The point is that I have lost any ambition I had for trying different speakers. It certainly seems that when I listen to my system I am in very great measure listening to the character of my room - and I have lost any ambition I might have had to try different speakers in my room. I know that you read that the room sound dominates but it is really interesting to actually hear it.

By the way anyone who is interested to come and have a listen is very welcome indeed - just to test if I am actually losing touch with reality (always a possibility at my great age I hear Mani saying).

P

[Robert]

The ROOM is the final frontier as in Star Trek.

It is the single biggest factor in great or bad sound next to poor setup.

I have an average room but get a reasonable sound.

I've heard mediocre systems sound incredible in great rooms and $100k systems in poor rooms sound terrible no matter what we did.

I have yet to go down this road but sound traps etc are worth investigating.

I've decided I will have to build my golden sound room. Very few domestic dwellings are good for sound.

High ceilings are worth going for especially in older places. I've found higher is better even in smaller rooms (3 metres or higher).

[Flecko]

BUT they completely lost their attractive bass quality in my room and sounded light in the upper bass in just the same way that my speakers do.

I hope nobody will kill me but that is a problem I know and I have solved it with using an active pre amp (NOT by turning up the bass volume, which is not possible with my pre).

[Scroobius]

Hello Fellow Addicts  -  I have just made a very substantial improvement to the sound quality of my system and I have to say I am really surprised I was not expecting such a change.

I mentioned elsewhere that I have a very difficult room. So I re-read the Audio Note AN/E speaker placement manual (when all else fails read the manual). My speakers were placed so that the rear firing port was about 15cm from the back wall. Close enough I thought and that was with the speakers placed as close as I could get them to the back wall. So after discussion with Peter Q he said that in really difficult hotel rooms they always placed their demo AN/E's almost touching the back wall.

So I out came my drill and hammer and chisel and I attacked the walls to allow the speaker stands to be placed actually into the wall / skirting board so the speakers could be moved closer to the wall. The rear facing ports are now about 3-4 cm from the back wall. Wow what a difference there is now serious foundation rattling bass but more important the sound is much more pleasant to listen to in the upper bass and also higher where piano is richer and much more pleasant to listen to. The system has lost the slightly over analytic / technical character it had before and sounds sooo easy to listen to - it definitely has that "stay up all night sound quality".

So a few cm difference in speaker placement has made a really big difference. Maybe the AN/E's work in a different way to other speakers using the back wall as "part of the speaker" to launch the wave (allegedly) but whatever I am now going to focus on other room set up tweeks if I can get this much improvement with such a small change. I have just received my "Get Better Sound" book by Jimi Smith so lots of reading to come.

It would be interesting to hear of any other similar experiences by fellow addicts.

Cheers - time for another glass of red wine and still looking forward to the Whisky Peter owes me he ha.

P

[Robert]

Sorry to be a downer but ports are a constant source of problems. Inherently designed in the old days to make up for deficient bass or give the effect of more bass.

Try blocking the ports completely using a clean rag and listen. My Tannoy's came with foam plugs but I have blocked them completely with drain tester plugs.

Better bass now exists. The signal coming of the back of the driver can never be exactly in time with the signal coming from the front.
It makes these speakers problematic to get sound right in rooms especially bass and even harder to match with sub woofers.

[Robert]

A piece from "The Soundoctor" white papers, of interest re ports(This is from an article integrating subs but is still relevant to all loudspeakers):
http://www.soundoctor.com/whitepapers/subs.htm

TYPES OF "MAIN" SPEAKERS

In addition to all the above, there is the complex issue of the "main" speaker you are coupling to. There are essentially 6 types of speakers that exist:

1) sealed
2) port in the front
3) port in the bottom
4) port in the back
5) a dipole, which is a flat panel such as an electrostatic (Sound Lab, Magnepan, Quad, Beveridge, Martin Logan, etc.)
6) an true omnidirectional system such as the MBL or the BEOLAB 5.

Each of these speaker types couples somewhat differently to the room, and certainly to a sub.

A port is ALWAYS nothing more than a cheap way to attempt to get free bass out of an enclosure and /or driver that's too small. It's a holdover from the 1930's when because of driver inefficiencies (especially when compared to today's units) you had to do everything possible to increase the useable output over the desired range of frequencies.

At one level, all the guyz want 9 foot speakers in the living room (read "man-cave"). All spouses, of whatever gender, want tiny 3" speaker cubes that disappear, but expect 9-foot results from them. Since they haven't repealed ohms law or any other laws of physics while we were sleeping, the only way to get correct sound is to move a correct amount of air.

Lets examine ported speakers. We'll start with the worst case, the port in the front. At mid bass frequencies, say 50-80 Hz, the LF driver moves IN the cabinet, the air in the cabinet is elastic, and the port air moves out of the cabinet. Because of the frequency at which the cone is moving, by the time the cone moves back out again, the port air is now moving out, so in front of the cabinet the two air pressure sources sum together and you get a fake bass "bump" or "boost".

As you go lower and lower in frequency, at some low frequency the air pressure from the LF driver and the air pressure from the port are exactly opposite each other, so they cancel, and there is no more audio at that frequency: it disappears. This defines the -3dB "cutoff" point of the cabinet in question. When the manufacturer of a speaker cabinet defines the frequency response (i.e., 37 Hz - 20kHz +/- 4dB) this is what is defined by the entire arrangement of the port and the air in the cabinet and the driver.

You must understand that ANY driver goes down to 0 Hz, or DC. If you put a battery across a speaker, the cone moves out and stays there. If you were to have a DC coupled power amp feeding a speaker - ANY speaker, from a 1" dome tweeter to an 18" rock n roll stage bass driver - and you put 4 Hz into it, it would simply move back and forth at 4 Hz. Of course in order to actually "hear" the audio it would have to be in the generally accepted passband of 20-20,000 Hz and the cone diameter would have to be enough to actually move some air in the room. So it is the overall combination of the driver size, the excursion, the box size, (therefore the air back pressure) and many other factors that determines the overall response of that "speaker" AS AN ENTITY.

That means IF you were to simply put those same frequencies through the mains and the sub (that means with no crossover, and this is the mistake that nearly everyone makes) you would now have 3 sources of LF energy and differing phase: the 'main' LF driver, the port, and the sub, all fighting with each other. A further corollary is that since the air inside the [mains] cabinet is elastic, the phase relationship of the port air to the driver air is also a sliding one; that means it's "out of phase" — and smearing — over a wider range of frequencies than you might think.

If the port is on the back, again a cheap attempt to use the back wave bouncing off a wall to give 'additional' bass, you have the ADDITIONAL issue of the transit time it takes for the back port pressure (already delayed because of the elasticity) to leave the cabinet, travel back, hit a wall, and bounce back around the front of the cabinet again; therefore this LF wave MIGHT be "in phase" with the front driver BUT BE 360 OR EVEN 720 DEGREES LATE; therefore it sounds like the bass frequencies are ok in the frequency domain but the IMPULSE RESPONSE is now muddied.

Also, in the case of back ported or (type 5) dipole speakers, since the path length from the back of the speaker to the wall and bouncing back around to the front of the speaker is a fixed physical entity, at some frequencies you are adding and at some frequencies you are canceling: you have simply made a physical/mechanical frequency comb filter that you can't do anything about. Sound Lab's answer to this (for use with their flat panel electrostatic speakers, which are dipoles) is they sell you a "Sallie", which is an absorber to absorb the entire back wave output of the electrostatic panel. Since now there is no comb filtering; all you are therefore hearing is the front signal.

[pedal]

A piece from "The Soundoctor" white papers, of interest re ports(This is from an article integrating subs but is still relevant to all loudspeakers):
http://www.soundoctor.com/whitepapers/subs.htm

Robocop,

I find this lengthy post rather misguiding.

The theoretical principals discussed are of course valid, but – you know – sometimes theory and practical life doesn’t always agree. The main point here is not the choice of principle, but how well it is executed.

A ported shoe box sized speaker will indeed have typical problems in the bass, as described in that “white paper”.
But a large floor standing speaker with a 12” bass driver and a proper port tuning, can perform exceptionally well in the bass.

I have heard panel speakers with exceptionally good bass performance, too.

Keep in mind, that musically speaking, the most important register in the bass is what’s going on above 40 Hz, not below 40 Hz.

This is based on my own experience from owning several costly loudspeakers of various principles.

[pedal]

I have to say at this stage that my room acoustically is bad - very very bad!!!! - you would not choose my room if you did not have to!!!. It is the kiss of death to most speakers. It is "L" shaped with the speakers firing down the long part of the L and the short part (kitchen) of the L to one side of left hand speaker. Not at all symmetrical acoustically. To make it worse the long part of the L is a long thin room - really bad for acoustics. I used to have big transmission line speakers (that particular pair just sounded awful) and before them a pair of Quad ESL - they used to sound great in my old house (taking into considerations the limitations of Quads in the dynamics and bass department) but in my current room they sounded just plain awful. So I have to be pleased that the sound I now get is quite good.

Could you post a drawing of your room, including size and speaker/listening coordinates?

[PeterSt]

My advice : Read Robocop's post again.
And again if needed.
(I didn't read into the given link, so no judgement there)

There is not a single word I don't agree with. But, it is also not much common thinking I'm afraid.

My speakers are there - and arose in close coorporation with the designer/builder of them. And Paul, you may not know or have noticed, but my woofers have downfireing ports as well.

Indeed, the ports are there to gain some Hz on the donward side. But in effect it doesn't work like that. It seems to work because indeed you'd be received lower frequencies from it, but I STATE : this is because of a distorted wave (again read Robocop's post);

Envision this distorted wave as an addup or cancelling out onto itself (because of lag in the speaker and reflections from another source (with the diaphragm as the real source). This creates lumps in the wave which certainly don't equal the frequency. And now the fun : these lumps (because of resonance) emerges at a LOWER frequency than the original. Hey, lower frequency !
... But never think it is correct.

Think about the name "Phasure" again. This is what I try to work with all over ...

I use horns not because I like horns, but because I makes me think less room reflections will happen. Less disturbing reflections.

Back to the speakers and their designer - all undoubtedly calculated and being in place ... I closed that port.
This *is* a bit easy for me, because I have subwoofers for the low end. But still, closing the ports made the bass better. And better is not lower. Better is the even (SPL) output at the real frequency. This lower output because of distortion ? think about it. There is NOT more energy, so all what happens is that the available energy (the volume level for that frequency, say an upright bass) will be spread over more frequencies. One of them being the false lower, and that deducted from the original. So, lower but softer (and false) and lower on the real frquency (which is just virtual because it has gone). Wrong wrong wrong.

My subwoofers of course also carry ports. Three of them, backfireing. With all three ports open, 12 Hz can be achieved "straight". Yea ? too bad that a 20Hz signal shows the 12Hz already. See ?
So these ports are closed too. It's fake and bad.

Think phase. That's all there is too it.
Now think what you could have going on to destroy it. The proper alignment of it. You crossovers and how they inherently destroy the phase alignment. What it takes to undo the anomalies; like 180 degree phase change and some nice delaying capactors and stuff to revert the 180 to 0. But now there's the delay, and its timing is frequency dependend ...

Think about why speakers should NOT be close to a back wall. And, if it's per design to be close, think about the why. But also that this is not about "just close" but about getting a 220 etc. degree phase shift back to 0 again. With delay of course ... And how a low frequency wave is affected by this delay. 40Hz is not much you know. If you'd be able to delay a 40 Hz wave by say half of its cycle, the delay is still 1/20 second behind the real music. That's muddying.
Or, now thinking about the reflecting higher frequencies, how a fixed reflection distance can work for only one frequency and its harmonics (plus the same delay but much shorter now, and possibly less bad for that reason); but all of those other frequencies ? they will be distorted again. Distorted by their own reflections.

So, completely dampen the room ? Not necessary. But think about how sound decays at travelling through air, and WHY it decades. Why ? because it's not in a single direction. Otherwise it would be quite alright and you could hear a sound for miles of distance (think about the railroad and how the sound is captured within the metal; it can't escape).
So, sound spreads (I didn't dig up the formula), and its reflections on the walls spread too. The reflections may (!) have decayed so much that by the time it reaches your ears it is harmless. But then with a normal spreading speaker (unlike horns) you are asking for sound to go right under ~180 degrees right to the side walls. Now dampening that *is* important.

This all is one of the reasons I don't have a real sweetspot and merely can listen about everywhere in the room with great pleasure. But, this was also an explicit objective, and this is how the above comes to mind.

2c
Peter

[Flecko]

My 2 cents:
Try another amplifier. -> I just bought a Rotel RB-1070 to make an experiment. It is not expensive on the used market and it has 120w/8ohm meassures very good and has a big damping factor. The result compared to my 80w/8ohm class a amps: Much more and better controled bass and overall better sound. I also thought about the gain clones but I found them not powerfull enough to drive speakers with 82db@1W. The Rotel will be replaced by a Chord SPM-650 which has more or less the same specs but it is a more "high end" design. Will see what that will bring to the sound.
Having a two way design with the port on the back is maybe a problem. -> Try a three way design, then you can place the port on the front. That will bring a deeper and better sounding bass.
Don't waste to much time and money on your room. A good system can sound good in every "normal" room, even if it is L shaped. I see the problem in
1: Amplification
2: Speakers

Greetings
Flecko

[Flecko]

PS:
I just found that the Audio Note should have an efficiency of 97db...with a two way design it is not possible to get a deep bass and such an high efficiency. No way. Either the speakers are not as efficient as they claim (then your amp is maybe to small) or they can not have the bass you want from them. Do you have meassurements of the speakers?

[Scroobius]

Hi Robo - Well certainly I agree this is a strange result and not what I would expect for sure. And yes the Audio Note AN/E's are quoted at 98db efficiency and a frequency response of 18 Hz to 23 kHz at -6 dB.

But surely 18Hz and 98db are ridiculous and impossible figures for a ported 2 way design with only an 8" base driver (just do the helmholtz calcs.). I have to say I always thought these figures were produced by the "marketing department" rather than the "techies". But I just tried a test tone of 20hz and there is plenty of output in my room at that level (and organ music can move the foundations very impressive). And the sensitivity? - well I tried a pair of PMC transmission line speakers in my room and needed to increase the output level around 8-10db to get a similar output. Not very scientific granted but certainly my speakers are much more sensitive than the PMC's at 88db sensitivity. Also my room completely robbed the PMC's of their base output - and in their normal abode these PMC's have plenty of very good sounding base. Anyway that is another story.

So to get back to the AN/E's I am told that they work in a way very different to other ported speakers.  I really don't know about that but the specs indicate that they may do - who knows? I certainly don't but I have tried many other speakers in my room (Quad ESL, Transmission Lines (my old home made types) small normal ported designs and the PMC's) and they all sounded very poor. The story I heard is that the AN/E's design has elements in common with horns and use the back wall to achieve that (?) - how they would do that I do not have a clue.  Another interesting thing though is that positioning speakers close to walls normally robs the sound stage of depth flattening everything out. With the AN/E's closer to the back wall that aspect has actually improved (but not a huge amount really). But just the fact that I still getting a good deep sound stage is surprising.

Just out of interest I just stuffed the ports with rags and it ruins the sound quality - less dynamic less bass squashed sat on quality to the sound.

All the best

P

[Flecko]

Not very scientific granted but certainly my speakers are much more sensitive than the PMC's at 88db sensitivity. Also my room completely robbed the PMC's of their base output - and in their normal abode these PMC's have plenty of very good sounding base. Anyway that is another story.

I would interprete this as an indication to blame the electronics. If the PMC's normaly have bass and on your system have no bass, it could be the room BUT in my book it should be the amplification. Do you have the possibility to try an amp with more power and an higher damping factor? Maybe a good preamp too?  Even if the AudioNote would have these fantastic specs, the bass (8" speaker) still has to be controled and therefore  a higher damping factor could help.

Hi Robo

And its me, Flecko

[Scroobius]

Well the one thing I do know is that the room has a massive effect on sound quality (and especially this room). Here we tried the PMC's with my amps and the very high powered MF amp they are normally used withy. No change in electronics made any significant difference in sound balance - but there were differences in clarity and detail (nothing came close to the GC).  No matter what the electronics the PMC's just sounded thin and lean in this room as have other speakers. This is nothing to do with electronics - I moved the AN/E's closer to the rear wall and that is what made the really big difference same electronics nothing else changed.

I have powered these speakers with some very different amps (SET's tranny etc) and whilst there were differences the overall character and balance of the sound was not that much different. Whilst the GC's I now have are head and shoulders above the other amps I have tried even they do not affect the balance of the sound.

Check out the book "Get Better Sound" by Jimi Smith and in that he explains why. His whole career has been sorting out sound systems by "voicing" them to the room they are in. Peter S took steps to minimise the room effects as he stated earlier in this thread precisely I assume because he knows that room effects dominate.

Cheers

P

[Flecko]

Thanks for the explaination. I realy would have guessed on the electronics but there are many undiscovered worlds to discover as it seems...maybe I have to try the gain clones too...but for now, a chord spm 650 it will be

Anyway, what a strange room you must have