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tannoy legacy series

That’s the same as me - 31 years and it’s still the same set up . Ive had 3 different 12” drivers in that time and crossing a foot or so in front of me has always given the most lifelike 3D image and satisfying soundstage.

Nice to know. I have arrived at a similar set up just need to get the protractor and measuring tape out to see if I have managed to get to the 30 degrees and 1ft position.:)
 
When you say 30 degrees, is that the amount of toe-in with a starting position of the speaker cab being parallel with the front wall? i.e. You're not starting with the tweeter aiming directly at the listening position and toeing in a further 30-degrees from there?
 
When you say 30 degrees, is that the amount of toe-in with a starting position of the speaker cab being parallel with the front wall? i.e. You're not starting with the tweeter aiming directly at the listening position and toeing in a further 30-degrees from there?

I would need to go back over the thread and the associated docs as it was mentioned in there. My guess is 30-degrees from the speaker looking directly at you. I have them crossing in front of my listening position possibly too much but would need to measure to be sure.

Sorry for droning on but the Cheviots are getting nicer by the day.
 
When you say 30 degrees, is that the amount of toe-in with a starting position of the speaker cab being parallel with the front wall? i.e. You're not starting with the tweeter aiming directly at the listening position and toeing in a further 30-degrees from there?
Mine are 30 degrees in from them being parallel with the front wall. They cross one foot in front of my ears.

This is a great free app, you can reset the angle to zero when parallel to the wall. Your phone or iPad will then give you the relative angle from there.

iLevelX - Clinometer for iOS
https://apps.apple.com/us/app/ilevel-protractor-level/id458980311
 
Mine are 30 degrees in from them being parallel with the front wall. They cross one foot in front of my ears.

This is a great free app, you can reset the angle to zero when parallel to the wall. Your phone or iPad will then give you the relative angle from there.

iLevelX - Clinometer for iOS
https://apps.apple.com/us/app/ilevel-protractor-level/id458980311

Thanks John for posting again :D. I will have to go looking for an android version or maybe check if the 'kids' have a protractor lying around from school days!
 
Interesting, I did some measurements and with my speakers setup 7.5 feet apart teeter to tweeter I have met all the required distances from front, rear and side walls to keep the reflection times greater than 6ms. I played around with 36, 30 and 25 degree toe in and found 30 to be the best, (axis crossing 1 foot in front of ears) for best timbre and soundstage.

jBX2j04.jpg

A very interesting read. I started to glaze over a bit by the end though, - it's been too many years since I studied trigonometry! I wish the author had written a little about the effects of absorption at the first reflection zones, as it would be useful to know how much closer it allows you to place speakers to the walls without violating the 5ms/6ms rule...

BTW, on page 5 it says:
"In Figure 4(a), for example, we see that in a 4m-wide room the stereo separation must be reduced to about 1 m to achieve 6 ms delay for reflections from the side walls."

This is presumably a misprint as, unless I'm reading it wrong, Figure 4(a) shows stereo separation of just over 2m satisfies a 6ms delay in a 4m wide room?
 
A very interesting read. I started to glaze over a bit by the end though, - it's been too many years since I studied trigonometry! I wish the author had written a little about the effects of absorption at the first reflection zones, as it would be useful to know how much closer it allows you to place speakers to the walls without violating the 5ms/6ms rule...

BTW, on page 5 it says:
"In Figure 4(a), for example, we see that in a 4m-wide room the stereo separation must be reduced to about 1.5 m to achieve 6 ms delay for reflections from the side walls."

This is presumably a misprint as, unless I'm reading it wrong, Figure 4(a) shows stereo separation of just over 2m satisfies a 6ms delay in a 4m wide room?
No you are reading it wrong...read up from 6ms mark on the delay axis, intersects the 4m room depth curve which then you can see the separation distance axis is only 1.5m. a room depth of 4.8m will hit 6ms at 2m sep'. However read on and see how toe-in helps improve things...
 
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Here's a quick n dirty toe-in set up;
Position your seat/speakers in an equilateral triangle with your speakers your preferred distance apart and you at the apex.
Your speakers should be on axis angled firing straight at you.
Move forward till you are on the edge of your seat, now re-angle your speakers so they are now on axis with this new position.
They now cross in front of your first seated position, sit back and relax, fine tune to taste.
 
No you are reading it wrong...read up from 6ms mark on the delay axis, intersects the 4m room depth curve which then you can see the separation distance axis is only 1m. a room depth of 4.8m will hit 6ms at 2m sep'. However read on and see how toe-in helps improve things...
I was referring to figure 4a (the side wall graph), but you're right I still wasn't reading it correctly. To achieve 6ms delay from the side wall the stereo separation in a 4m wide room should not exceed 1.5m.
 
I was referring to figure 4a (the side wall graph), but you're right I still wasn't reading it correctly. To achieve 6ms delay from the side wall the stereo separation in a 4m wide room should not exceed 1.5m.
Aye 1.5m, pesky scale starts at 1m not zero ;-)
 
Is this toe-in arrangement just for Tannoys or is it applicable to other speakers i.e. does it work especially well with Tannoys?
 
OK, now that my system is basically done, it's time to optimise as much as possible.

I'm considering those IsoAcoustics Gaias and a set of the Oreas under the amp. This won't be cheap but consensus seems to be that it's worth it. However, what else should I be considering? I've set a total 'optimisation' budget of £1k, to include acoustic treatments and isolation.

My thoughts are to see if I can get the isolation for the best price - I've contacted my dealer to see if a deal can be had - and hopefully with enough left over to fund the DIY creation of some tube-based bass traps to try to address the room nodes. I've no interest in fancy cables or changing anything else just now, and it might be that I decide to do none of this. But it's an itch I'd like to scratch if it means getting the last few % out of the kit I have.
 
I can only recommend what I’m using which is a solution that makes the most sense to me. Here’s a bit from Symposium’s website which describes the recommended usage of their absorption platform with roller bearings:

...if you are using HDSE Rollerblocks in conjunction with a platform under loudspeakers, in which case the platform should be placed directly under the speaker, in contact with its cabinet (with no spikes or cones in between), and the HDSE Rollerblocks should then be placed between the platform and the floor. This provides maximum energy drainage and damping to the loudspeaker itself and provides lateral wave isolation and decoupling from returning bass waves which propagate through the floor. This is a powerful combination for realizing the maximum performance a loudspeaker has to offer
.

Hope this helps.

A bit more regarding the platform:

Is a Symposium Platform an isolation platform?
Our platforms achieve a degree of isolation in the component by absorbing energy from two sources at once: from the component and from the support surface. Our platforms GROUND your component and give vibration that would otherwise be trapped inside of it a place to go, be dissipated as heat, and NOT be reflected back into your component (in either its original form, or a different, supposedly more benign one). You can think of our platforms as a kind of "sponge" for mechanical energy in the upper 8 out of 10 audible octaves- that is, from about the midbass (50-80 Hz or so) on up. These 8 octaves represent the lion's share of musical information, and by far contain most of what is needed to recreate a sense of "realism" and faithfulness to the original performance. But the word "isolation" is overused in this field of audio, because strict "isolation" is not the answer to the larger problem which we need to address, which is vibration control. Mechanical vibration affects the sound produced by your components because it works on the sensitive audio circuitry INSIDE your component, and merely cutting off one of the sources of vibration- the entry point at the feet of the component- without considering other sources, may not solve the problem completely or even adequately. It's important to drain energy from within the component as well as keep other external energy out of it. We therefore feel it is important that "isolation" remain a secondary and not a primary goal in the design of our products, and its role must be kept in proper perspective as only one of a number of disciplines necessary for better sound.
 
OK, now that my system is basically done, it's time to optimise as much as possible.

I'm considering those IsoAcoustics Gaias and a set of the Oreas under the amp. This won't be cheap but consensus seems to be that it's worth it. However, what else should I be considering? I've set a total 'optimisation' budget of £1k, to include acoustic treatments and isolation.

My thoughts are to see if I can get the isolation for the best price - I've contacted my dealer to see if a deal can be had - and hopefully with enough left over to fund the DIY creation of some tube-based bass traps to try to address the room nodes. I've no interest in fancy cables or changing anything else just now, and it might be that I decide to do none of this. But it's an itch I'd like to scratch if it means getting the last few % out of the kit I have.

I have recently added a set of Gaia under the Ardens here and am happy with what they (appear to) do. It is tricky to be specific as swapping back and fourth to do a meaningful with/without as all but impossible. The speakers are on a concrete floor so results will be in relation to this. As you know, the Ardens sound more than decent already and the changes are not nearly so obvious as eg. swapping to a cross-eyed set-up from a straight-ahed. Much more of a subtle, but noticeable, improvement in clarity.
By way of context, one of my speakers is in a corner and the first reflection point between it and me is a flat panel door. Looking around for what I had available to modify this door with, I found a number of pieces of 10mm thick wool felt which I then stuck to the door. I wasn't expecting much but the effect was to give much better balance to the image between the speakers, shifting it more central and generally cleaning things up. Overall magnitude of change was broadly similar to the Gaia under the speakers (but for much less cost!). Obviously this relates to a very specific situation and wool felt doesn't seem to be much mentioned in home acoustics. A quick look at treatments for office and public spaces reveals a much wider use. I guess it could make a listening room over dead but for treating this one area it worked well.
My first experience with IsoAcoutics was actually the pucks. I needed to put a pair of speakers on a large wooden sideboard and had expected problems so put initially three, then four pucks under each speaker. Difficult to say whether the speakers sound particularly different to when they were on stands as the room layout had changed as well, but they certainly don't sound worse and to that extent the pucks are doing their job.
 
I just added a set of their ISO130 stands under the active speakers I use with my Mac (fairly inexpensive Alesis M1-520s) and have been impressed with the improvements (which, to be fair, come mostly from the speakers now being off the desk). In fact, apart from being lacking in volume capability and having slightly noisy internal amps, the sound is extremely good through these - embarrassingly so. It also reminds me of just how much better small speakers sound in near-field (in my case ~1.5m equilateral triangle with direct toe).

(On an aside, I may flip these for a pair of Genelecs of the same size some time, should a pair come along, but wouldn't want anything bigger on my desk.)

So, my IsoAcoustics duck is broken, but I've yet to find the right deal on Gaias and Oreas to wade in. I do have something of a deal on the table but I am hopeful my local dealer can do something, rather than some random web shop...
 
Some good points regarding room acoustics from Earl Geddes’ book: http://www.gedlee.com/Books/HomeTheater.aspx

Lets now return to our discussion of the absorption in a small room. I have shown that it is desirable to have large low frequency absorption with little high frequency absorption, where there may be a few exceptions used to control specific early refections. In a practical sense, there is a real prob- lem with this requirement. Virtually all acoustical treatments for rooms have large high frequency absorption dropping to almost nothing at low fre- quencies, which is exactly the opposite of what we want. Clearly, dealing with the absorption aspects of a room by the use of standard materials is not recommended. The use of sound absorption in a small room must be dealt with extremely carefully. It has been my experience that it is almost impossible to make a small room too live at high frequencies. Most typical room construction materials and furniture have significant levels of absorption at high frequencies. Obtaining the right amount of absorption across the frequency band requires different construction techniques and room interior treatments.
I will return to the construction details in a later chapter, however, there are some specific topics that are more relevant here. How absorption actu- ally works is an important issue in our current discussion. There are two principle mechanisms for sound absorption.

The first is to use a porous material such that the sound wave can pene- trate it, and, in doing so, the air moving in and out of this porous medium dissipates energy through friction. This mechanism is by far the most com- mon, and there are some specific features to this kind of absorption. First, it becomes increasingly less effective as the wavelength of sound exceeds the thickness of the material. Thin materials will have no low frequency absorption. The second is that since the porous material works on the acoustic particle velocity, the effectiveness of the material is reduced when it is placed at locations of low particle velocity—places like walls where the velocity must go to zero. A piece of sound absorbing material placed on a wall is 1) not very effective and 2) increases in effectiveness as the fre- quency increases. This most common of all sound treatments is exactly the wrong thing to do.

The second major source of sound absorption is through the actual motion of the room structure—the walls themselves. Of course, if these walls are perfectly rigid—like poured concrete—then this mode of absorp- tion is negligible. But, for a common frame and dry wall construction, wall motion can be quite substantial. Since the wall has mass, its motion will continue to fall as the frequency goes up—that is, unless it has a resilient support structure. All walls must be supported in some way. When the sup- port is resilient (and all supports are to a certain extent, except for maybe a concrete backing), then there will be a resonance frequency and the motion of the wall will fall both above and below this resonance. A wall would typ- ically resonate somewhere below 100Hz—depending on drywall thickness and the method of mounting. When the wall does move, it dissipates energy through friction. (All absorption is friction of some sort.) The main differ- ence with this type of absorption is that it decreases with frequency rather than increase as the porous material method does. This would seem to be the ideal mode of absorption for a small room and indeed it is. In fact, if done properly tremendous absorption can be achieved at low frequencies with almost no high frequency absorption.

Another concept in sound absorption that comes into play in most HTs that I have done has to do with sound absorption on opposing walls. In my book Audio Transducers, I show how, at low frequencies, sound absorption works the same whether it is on one wall of an opposing pair or it is on both of them. By this I mean that the sound absorption is the same whether it is split between two opposing walls or all of it is placed on one wall. This is a good thing to know because it means that if we need to add low frequency absorption to a room, we need only do it on one wall of each of the three opposing pairs. I will show how this is a major advantage when locating a HT in a home.

In small rooms, the obvious preferred mode of sound absorption is to have the walls constructed in such a way that they deliberately move and absorb sound. This technique would never be used in an large auditorium because in those venues we are looking for primarily higher frequency absorption and hanging type materials, such as curtains or drapes are a good choice. In a small HT, the walls should be bare and hard but mounted so that they flex at low frequencies.

5.5 Summary
A complex chapter like this deserves a summary of its main points.
• The first is that the sound field in a room is a random quantity and one must do some form of averaging of samples (frequency responses) to get a valid estimate of the true frequency response.
• The modal region of a room, where there are true resonances, is limited to a relatively low frequency region never more than a few hundred Hertz.
• Damping in a room is effective at smoothing out the modal region but is detrimental to the steady state response at higher frequencies.
• Sound quality is strongly affected by early refections and the level of the reverberant field, and, in a small room, these two require- ments can be in conflict.
 


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