Andywilliams

Where's your sofa

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Super Dealer

Cancellation and reinforcement always occur that is physics, and evident if you glance at any ‘in-room’ frequency response plot.

You can of course design a loudspeaker for close to wall placement, where you make an allowance for the bass reinforcement .

I am not a fan of dipoles, where as smuch energy is propagated from the rear as from the front and the off axis is extremely ragged.

EQ is not adding electronics, simply reducing energy at a specific frequency , it is completely transparent and as well as allowing you to enjoy a completely full-range sound dramatically improves the sound quality in your room.

To limit your choice of loudspeaker to one that doesn’t have the bass extension to interact with your room is archaic.

Keith

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18 hours ago, Tune said:

The best advice came on the first page. Get a speaker that's -10db at 35hz and in ported. Position into the room to avoid the second resonance and simply enjoy your music.

Oh bugger I am such an arse - the problem is not with his current ATCs - so I owe you an apology for brushing off this response in the way I did.

However, to buy speakers that are down at -10 db at 35 hertz would just about leave him with what he has now (which are down by that amount) and with not the bass extension he is missing.   Your advice on positioning is right though .. away from back wall and even moreso away from side walls (unless the speaker is specifically designed to go back to the wall and in the corner).

Happy Christmas :peace:

Edited by uzzy

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Uzzy, no offence intended. Tony will hopefully confirm but I was involved with studying room acoustic modelling as far back as  2001 helping out Peter Lyngdorf with Tact at a number of shows and employing their system modelling with custom built systems.

Now if I could be arsed I could develop a genuine reason given, room dimensions, speaker positioning, roll off shape and interaction with room resonances etc etc. It's great to hypothesise it really is.

Sadly, because it was so long ago, it would take me an inordinate amount of time to look everything up. 

My post was on the basis of having a room of very similar dimensions. Now let's look at this - a ported design -10db at 35 hz measured anechoically

1002862681_ScreenShot2018-12-02at18_27_49.thumb.png.15b2ab1e218fa23d65a094d765807b88.png

What you will see, with the roll off and room gain model is that with room gain set at 3db at 50hz the design allowing for said gain is basically flat to 50hz.  The main room modes come into play just below this point and and it is here where the more rapid roll off of the ported design makes the fundamental room modes less intrusive allowing a flatter, more subjectively extended response.

Now I'm sure we can all hypothesise and I am the first to admit I've lost much of the technical knowledge that I had 15 years ago following injury but hopefully the above should go some way to explaining why the recommendation works in a room the size of the OP's. I'll take flat to 50hz and nothing overbearing below that anyday - and you are posting with someone who has owned far too many loudspeakers ( :) ), in a similar listening environment, including designs such as the ATCa 50TSL.

I think I was just offering the advice based on experience and laughing at the pages of people trying (as I used to) to use theoretical maths to solve a problem and coming to conflicting conclusions. No offence as I say. The graph is hopefully not me leaning too far into the unknown where my memory will make be look like a buffoon!

Edited by Tune
Postings.
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4 hours ago, Tune said:

I think I was just offering the advice based on experience and laughing at the pages of people trying (as I used to) to use theoretical maths to solve a problem and coming to conflicting conclusions. No offence as I say. The graph is hopefully not me leaning too far into the unknown where my memory will make be look like a buffoon!

None taken and I meant no offence to you.  I was just making the point that most loudspeakers 10 db down at 35 hertz have a sharp roll off from 100 hertz and so the bass response is curtailed.   So you may achieve no bass boom but won't you in fact be not getting any real deep bass at all?    

I know my room is 5 feet longer than the originator of this query but I have never experienced a bass boom problem with the Arts (which are ported and are virtually flat to 50 hertz mind but I wouldn't suspect the roll off to be that great down to 35 hertz) .  Mind you the port is upfiring so has little or no interaction with the rear or side walls.  Perhaps I have been just lucky in my choice of loudspeakers over the years (hence the necessity of home demo for any intended speaker purchase). 

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With some thanks and credit to Floyd Toole of Harman, here are some things equalisation can and cannot do:

1. It can help with some, but not all, loudspeaker problems. With comprehensive laboratory measurements to work from, equalisation can be used to make a good speaker sound better. Once a loudspeaker is in a normal room, you lose the ability to measure it in ways that allow you to be analytical. Without knowing what is wrong, you don’t know whether equalisation is the right solution for the problem. For example, equalisation can change frequency response, but it cannot change directivity, yet together they determine the basic shape of a room curve. Poor directivity control, as a function of frequency, can only be cured by using a better loudspeaker.

2. It can help with some, but not all, room interaction problems. At frequencies below about 300 to 500 Hz, the shape and size of the room, and the position of the speaker and listener within it dictate the system performance. Two factors are active here:

2.1-room resonances, some with quite high “Q”, cause note-to-note fluctuations in loudness, and boominess in percussive drum and bass sounds. Since room resonances behave as minimum-phase systems, once the peak in the amplitude frequency response has been attenuated using a matching parametric filter, the time-domain misbehaviour will also be tamed. It works.  For this one issue EQ can work. However, acoustical interference caused by the interaction of many reflected sounds with in the room are non-minimum-phase phenomena, and they cannot be corrected with equalisation.

So assuming you don’t go for EQ as it will not solve all the issues, here are some thoughts from an aging audiofool who used to understand this and is trying to rake through his mind!

Looking at the photographs up thread, The speakers are in really nasty places, equidistant from both read and side walls and quite close to both in comparison to the listening distance. This will cause many issues as explained in the second example with reflections interacting in unpredictable ways.

Looking again at the room layout, from a pure sound POV, speakers should be on the long wall and further from the side walls with an attempt through speaker choice or toeing in to control sidewall reflections above 500hz. This is from memory but make sure your speakers are an “odd percentage” into the room (so a 5th or 7th or 3rd). And finally make the distance between the side wall and the rear wall not evenly divisible (again 2/3 works well). Combined with the roll off discussed earlier you should have a fine system that will support bass to the limitations of your speaker as opposed to being overly compromised by your room.

Most of all, get a sound that allows you to talk about and think about your music, not the manner in which you try to replay it.

Edited by Tune
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Hi well reading the above post from tune looks like iam doomed as I can't change where the system is. Maybe I should just stick with what I've got as the Atcs sound good in every respect like I said before though there's hell of a lot of people with systems in worse positions than mine alot with speakers pushed against walls in corners where's mine have a fair bit of space around them. Plus I really do get lost with a lot of the technical side of graphs etc never mind I suppose it's better to know than keep trying speakers that are going to sound bad no matter how much you pay. 😔. Thanks to everyone whose replied. 

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Super Dealer

Speakers prefer to have  symmetrical positioning, if you got hold of a microphone and downloaded REW ( room EQ wizard) you could make comparative measurements of the speakers and listening position and choose the flattest response.

Toole/Olive’s research concludes that ‘good’ loudspeakers have a flat on-axis and a smooth and even off axis which mirrors the on axis, this is variously known as constant directivity or wide and even dispersion.

Today you can enjoy completely full range sound in your room, with tight muscular bass with no ‘boom’.

Keith

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14 hours ago, Andywilliams said:

Hi well reading the above post from tune looks like iam doomed as I can't change where the system is. Maybe I should just stick with what I've got as the Atcs sound good in every respect like I said before though there's hell of a lot of people with systems in worse positions than mine alot with speakers pushed against walls in corners where's mine have a fair bit of space around them. Plus I really do get lost with a lot of the technical side of graphs etc never mind I suppose it's better to know than keep trying speakers that are going to sound bad no matter how much you pay. 😔. Thanks to everyone whose replied. 

Let's not forget Andy that many speakers were specifically designed to utilise boundary reinforcement - older corner horns like Altecs, Tannoys and JBL's being good examples (if sadly impractical in your case!).

Such designs are still massively popular in many markets, simply because they often work better in typical domestic settings.

Not all loudspeakers are designed for free space mounting ( away from the walls) - indeed many of the very best monitors are designed for half space (wall) mounting.

Often, moving the speaker just a few centimetres forwards or backwards, side to side, or even up and down, can have a dramatic effect on how it interacts with the room and the resulting consistency of the bass response. Ideally, the distance between the speaker and back wall should be different from that between the speaker and side wall (as I mentioned)l, and also between the speaker and ceiling/floor.

I know where I would put the speakers (for a big powerful, room filling sound) but I haven't met your wife :) 

I wish you luck.  Just try to remember that the music system is a means to an end - not the end itself.

Edited by Tune
removed lots of technical s**t as it's far less important than just listening to your music.
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Looking at the pictures I would suggest that you should try some acoustic panels in the corners behind the speakers.

side reflection  - it looks like you don't use the fireplace- are you able to put a panel in front of it ? You could even paint the panel to look like the fireplace. Maybe a panel over the radiator.

We seem to spend far to much money on equipment, and be too quick to try 'another speaker' without exploring other avenues with regards to room treatment first. I'm not talking about sticking egg boxes on the walls,  there is an infinate amount of fabric available, that you and your partner could agree on, that needent look incongruous or out of place.

the information is out there.

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google Bluefrog Audio - they have reasonably priced acoustic panels and their website gives you all the information you will need.

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Hi after getting advice from tune I moved my speakers 3ft from the back wall (behind speakers) there now 18 inches from the side walls toed in the speakers are 8ft apart my listening position is roughly 10ft away now so much better than before even though I didn't get bass problems with the Atcs everything now sounds much better would never have believed moving them could alter the sound so much. I am going to put something on the back wall when I get round to it . Thanks Tune.

Edited by Andywilliams

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On 04/12/2018 at 11:30, joolz said:

google Bluefrog Audio - they have reasonably priced acoustic panels and their website gives you all the information you will need.

Hi jooles I've ordered some bass trap panels for the wall behind the sofa from bluefrog audio just to cover the whole back wall I hope it will given the new speaker placements (made a big difference to the sound) and doing this ill be able to upgrade to a good quality bookshelf without any problems.

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Good to hear, none of us do, but room treatment should almost be decided at the outset, and this will benefit whatever choice of equipment you make, so that you should hear everything as good as it can be - before deciding that maybe you don't need to spend the money on that upgrade after al......who am i kidding...

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Super Wammer

In my experience, room issues will not be solved entirely with a speaker change.

I have found, bringing the seating position away from the rear walls really helps with bass boom, even if its by just a foot or two, adding some soft furnishings (curtains etc) can help even before proper room treatment.

My room, with the seating position around 4ft from the rear wall, has a pronounced peak @ ~32Hz and dip @ 48Hz, this is noticeable on all the speakers I have tried in my room. Below is some measurements with REW/UMIK-1 Mic of a variety of speakers, the KEF Reference 201/2, Frugelhorn Lite and DIY Supravox Full-Range speakers.

The KEF 201/2 has excellent bass response, a ported 3-way stand-mount that has generous bass performance for its size produces quite a large peak. The Frugelhorn Lite speakers actually start rolling off at around earlier than 100Hz and very little output normally below 60Hz, but as you can see in my room, it brings it up around the 65Hz area, as well as some output at the 32Hz peak.

The Supravox Full-Range driver speakers I currently have are a happy medium, designed to work in the room, with no crossover or Baffle Step Compensation taking into account of the design, that I have planned to be room-friendly.

40756636054_ef33d6a3ed_b.jpg

FHL Vs 201-2 FR (Stereo @ Seat) by Robert Seymour, on Flickr

30048410637_6c22d2cc8e_b.jpg

Supravox 165-2000 (L) Distortion by Robert Seymour, on Flickr

I would recommend getting REW, a USB Mic and start measuring what you are hearing, so you can then alter accordingly. You may find, that some speakers just do not work in your room, I have had that with the little Neat Petite III, larger Tannoy Stirling HE & KEF 104/2 I just could not get to work on the bass.

It would be worth using your existing speakers, and playing around with placement of the sofa, speakers  and maybe try some temporary room treatment, even with pillows or a mattress for example, just to see what effect it has.

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Super Dealer

But you can make them work, it would be simplicity itself to make a little filter to reduce the 32Hz room mode.

Thismight be useful to help you determine the cause of the massive cancellation centered around 50Hz.

http://www.padrick.net/LiveSound/CancellationMode.htm

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