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LenehanAudio Loudspeaker Design Thread

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   11 hours ago,  niss_man said: 

What I was talking about was your 45 degree off axis graphs or in basic terms the dispersion or how the speakers beam/do not beam. (posted on the 2nd page of this thread). As you know a speaker will lose its off axis energy when they start to beam and is related to cone diameter. One can design to allow for this ie. allow for a lower crossover point. The thing is one speaker designer may design for an even on axis response and believe that this is the best way of going about things and another designer may design for an even off axis response (45 deg or such). I can see your design is nice and flat 45 degrees off axis without big peaks and dips obviously because of good phase coherency between drivers at the crossover point because of a well designed crossover....but to show the other manufacturers specs at 45 off axis as well and show that they are not as flat makes people think that your ones are the superior product. "Well they are," I can hear you say, but B&W or other manufacturers may design their speakers differently with lots of time and effort, testing, auditions etc and have come to their own conclusion/opinion that their speaker sounds the best. After all it comes down to what the listener likes most. Some will love a B&W others will love the Kef and each one will have different on axis, and off axis plots as a result of many factors.

 

            Which "polar plot" sounds the best to the listener is what I think it all boils down to (well that and the distortion characteristics of the drivers/speaker).    

 

          When you perform your measurements Mike you gate your measurements to produce a "quasi anechoic measurement" in room( I can see that because of the low frequency drop off). So the 45 degree off axis graphs you showed should not have any floor reflections in them. 

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Hi Simon

            Yes indeed they are superior ! And unless there are scientific , acoustical or reasonable arguments to the contrary a speaker with the flattest power response will sound more accurate,musical and real than one with a wild off axis response. 

 

We we are speaking here about dynamic speakers with cone bass drivers and dome tweeters ! And in respect of these speaker types it's the Dome tweeters flare at the bottom of its passband that is the main offender in respect of that hard brash sound that is the signature of most less than 3 dimensional conventional loudspeakers . 

You know what lads I think I might start a new loudspeaker design thread and continue from there :).    Mike 


 

 

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Something that may (or may not) be relevant to this. I have a tiled floor. When I posted photos of my setup a while back, everyone said "you have to put a mat between the speakers". Well I tried this, and it unacceptably dulled and muddied the sound to my ears. My room did have a slight echo in the midrange that I needed to tame,  but I achieved this by placing mats as close to the most live spots in the room as furnishings and walkways would allow (as determined by clapping and listening to my own voice), outside of the listening area. This controlled the echo, without dulling or muddying the sound. The thing is, I suspect that if Mike's speakers didn't have such smooth off-axis response, i would have had to choose between dull/muddy and glary (from the floor reflections off the tiles). But with Mike's speakers, the reflection is clean, so I could have my cake and eat it too.

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Hi Lee

           have to say that what everyone said is usually right ! a rug on the floor between the speakers and listening chair normally works well .

Again it's the tweeter flare energy off axis that causes excess energy in the upper midrange lower treble area . When the woofer beams off axis it's more a sin of omission !

So basically a tweeter flaring sounds like a glarey bright sound  >  the information and detail is there but it's covered up by a facade of one note whiteness.

Now a Woofer beaming is less obvious > the information isn't there in the first place usually the midrange area is simply not there and varies between 4 and 10db down.

 

I'll post some measurement pics over the weekend and describe in a bit more detail whats Happnin Lads              Regards Mike Lenehan

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So this flaring of the tweeter. Would this be seen in a 45 off axis measurement as a peak in the 3-6k region with everything else flat.

 

Or does it show up with a 45 off axis response where the response is flat(well not really), but has dips either side of the 3-6k region. A bit like the one of the Proac DB1 you posted before. Which does look very poor. 

 

IMG_6593.JPG

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This one you showed of the sonus faber(45 off axis) looks not too bad. Would I be right to assume that this has a slightly laid back sound due to the slight 1-8k scoop and would be good in most rooms with not much room treatment.

Where as a speaker with a more flat response off axis  would sound a bit bright in an untreated room ?  

    or does the scoop just accentuate the  8K Hz peak so making the speaker sound brighter than a speaker that is nice and flat off axis? 

 

IMG_6591.JPG

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2 hours ago, niss_man said:

This one you showed of the sonus faber(45 off axis) looks not too bad. Would I be right to assume that this has a slightly laid back sound due to the slight 1-8k scoop and would be good in most rooms with not much room treatment

Reasonably big scoop  :) 

 

You want each angle to be ideally the same shape as others....   when they are different, ie. the delayed sound has a different spectral balance to the earlier arriving sound .... the brain interprets this as new "information" (which isn't in the recording, so obscures the recording)

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47 minutes ago, davewantsmoore said:

Reasonably big scoop  :) 

 

You want each angle to be ideally the same shape as others....   when they are different, ie. the delayed sound has a different spectral balance to the earlier arriving sound .... the brain interprets this as new "information" (which isn't in the recording, so obscures the recording)

So how does this affect the perceived sound. Is the sound more laid back as a result of the 4db scoop between 1-8K? This would suit a room with little to no treatment then am I right?

 

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It's very complicated to generalise like that, and boil it down to a simple answer.

 

In general though I would say no.

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On 12/8/2017 at 10:05 AM, Lenehan Audio said:

Hi Lee

           have to say that what everyone said is usually right ! a rug on the floor between the speakers and listening chair normally works well .

Again it's the tweeter flare energy off axis that causes excess energy in the upper midrange lower treble area . When the woofer beams off axis it's more a sin of omission !

So basically a tweeter flaring sounds like a glarey bright sound  >  the information and detail is there but it's covered up by a facade of one note whiteness.

Now a Woofer beaming is less obvious > the information isn't there in the first place usually the midrange area is simply not there and varies between 4 and 10db down.

 

I'll post some measurement pics over the weekend and describe in a bit more detail whats Happnin Lads              Regards Mike Lenehan

Have you got any more info and pics regarding the tweeter flare as I'd be interested to see what you mean by "flare"?

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On 8 December 2017 at 5:05 PM, niss_man said:

So this flaring of the tweeter. Would this be seen in a 45 off axis measurement as a peak in the 3-6k region with everything else flat.

 

Or does it show up with a 45 off axis response where the response is flat(well not really), but has dips either side of the 3-6k region. A bit like the one of the Proac DB1 you posted before. Which does look very poor. 

 

IMG_6593.JPG

Hi Simon

.               Let's look at the 45 degree off axis  measurement above .

this is a three way speaker but the measurement is only relevant down to about 300hz. Having said that one can see how the 6 inch midrange is beaming as its output is well down at 1500 hz .

 

Next we can see that the tweeter output is at full level at 3000hz ! This is because the tweeter is a dome unit so it's lower frequency output is very linear and flat across a 0 degree to 45 degree arch !  But it's linear only at the bottom of the passband then it collapses at higher frequencies just like a cone driver does (but for different reasons ) 

 

Because of the shape of a dome and the fact that the dome is being driven at its edges by the voice coil ,it's obvious that the most efficient air moving part of the dome is the front face . 

 

As the frequency goes up a dome tweeter becomes less efficient at producing higher frequencies off axis . This is a function of the diminishing frequency wavelengths of higher frequencies which tend to just get slid out of the way by the diaphragm off axis instead of being effectively pushed forward by the diaphragm .

 

I have usually found that speakers sound more like their off axis response than their on axis response . You can imagine how many speakers can sound a bit HiFi like and Glarey when this tweeter flared response is being aimed at every floor ,wall  and ceiling in the place. 

 

This is is why a speaker with a very smooth flat off axis response can sound musical and detailed in a less than fully treated dead room . 

ljmac said exactly this in his previous post !! He prefers his ML2Limited with no damping or rugs on the floor ! A testiment I think to the very smooth flat off axis response of the ML2.         

 

Im exhausted I need a decent Red !!    Bass driver beaming is another story as well of course.          Regards Mike Lenehan

 

 

 

 

 

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52 minutes ago, Lenehan Audio said:

    Im exhausted I need a decent Red !!    Bass driver beaming is another story as well of course.      

   Regards Mike Lenehan

Can I ask a few of more easy questions before or during your red wine thanks Mike?

 

When designing speakers in the past, I have used the on axis measurements of my drivers at 1m  with a gated/quasi anechoic measurement. 

1. Am I better off designing my crossover with 45 degree off axis measurements?

2. How far away should the mic be placed with these measurements?

3. Do you measure with a gated measurement technique?

      If I design crossovers using 45 degree measurements, my on axis measurements will obviously be different.

4. What on axis response am I likely to get when designing crossovers with 45 deg response measurements? (any example graphs?)

 

As you know, I enjoy building speakers and amplifiers as a hobby and I try to learn something new with each project and get a better result each time. Learning from someone like yourself is a invaluable tool so thanks for your input.

 

Cheers

 

Simon 

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Hi Simon 

this is the beginning of all the horrible complexity I'm afraid . Determining what type of responses are optimal on axis and at varying degrees off axis means first setting up the drivers on your proposed test baffle And working out response step characteristics. 

different shaped domes have different flaring and high frequency extension characteristics.  Flatter type domes have a very different off axis performance to more curved or round domes ! So the first question is tough to answer Simon . 

 

I can say that with a speaker say like the ML1 the flattest response should be around the 30degree mark . The on axis response will of course have a slight rise in the extreme top . With different speakers ! 2 way , 3way and  floor standers I'm afraid it's all different because of the beaming and flaring of different diameter base and mid drivers . Then of course all the slightly different shapes of dome drivers and there flaring characteristics .

 

1m is the default distance for measuring ! The reason is that with gated sinusoids or MLS ( maximum length sequences) the lowest frequency you can measure with is around 350hz because this is where the floor reflection is . It's a mistake to measure wideband because  under around 200 hz all rooms are subject to significant but different room gain ( room gain at 40hz is usually around 6db)

 

The subject is way too complex for simple answers 🙀. Also from 0degrees to 45 degrees your Xover anti phase must also remain at a minimum of 25db deep.

 

To round this up I would try and design at 1m and 30degrees off axis with a slight downward tilt with increasing frequency. Then see where it's at 15degrees and at 45 degrees. If you can take say an average measurement of 4 samples 0 to 45 degrees  ( one at 0 , 15,30 and 45 )you may find it sounds like the measurement looks 

                Whoo that was a beauty .      Regards Mike Lenehan

 

  

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13 hours ago, Celts88 said:

Makes perfect (double dutch) sense to me :P

I occasionally chat to Mike about speaker design issues.

 

I can usually understand what Mike says being a bit technically minded.  I mention to Mike though my knowledge taps out at Vance Dickinson's The Loudspeaker Design Cookbook which I read many years ago.  Mike says - I read that.  Without doubt he like me read it many years ago - but has gone way way beyond it since then.

 

Even with my background there are some things Mike says that are way over my head - knowledge just seems to ooze out of him - and that's not his 'secret' stuff such as his own port alignment, and how the PRC crossover works.  But it works - his crossovers are the best I have heard and his port alignment is the only ported design I have head I really like - mostly I prefer transmission line (which are hard to find).   Mikes ported designs sound like transmission line to me - how he does it beats me.  The only snippet he let slip one day - is - most textbooks and other designers have got it wrong.

 

I was at Caxton Audio one day and David (the owner) said to me - Bill you know Mike.  I said - yes - but that's not exactly hard - many customers do.  The in whispers - why do his speakers sound so good.   I said - no secret.    Well what is it?  From many many years of experience he has learnt a lot - things other designers may not even know.  Somehow that didn't satisfy him.

 

There is also another secret.   Never, ever skip on what you use inside a speaker.  He always uses low gauge air coiled inductors and at least Erse capacitors.  You may think any decent manufacturer would do that.  But having seen the insides of some very famous speakers I will not name that cant be said of many, or perhaps even most speakers.   

 

And no - I am not speaking of B&W (people know I am often critical of that very famous brand) - many years ago they did but these days use air cored inductors and good capacitors like Mundorf.

 

Thanks

Bill

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17 hours ago, Lenehan Audio said:

To round this up I would try and design at 1m and 30degrees off axis with a slight downward tilt with increasing frequency. Then see where it's at 15degrees and at 45 degrees. If you can take say an average measurement of 4 samples 0 to 45 degrees  ( one at 0 , 15,30 and 45 )you may find it sounds like the measurement looks 

                Whoo that was a beauty .      Regards Mike Lenehan

 

  

So a slight downward wilt would be ? 1k-20k with tilt of 1db?

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This is a place to start ! Yes nearly flat maybe 1 db attenuation .  Regards Mike

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9 hours ago, bhobba said:

I occasionally chat to Mike about speaker design issues.

 

I can usually understand what Mike says being a bit technically minded.  I mention to Mike though my knowledge taps out at Vance Dickinson's The Loudspeaker Design Cookbook which I read many years ago.  Mike says - I read that.  Without doubt he like me read it many years ago - but has gone way way beyond it since then.

 

Even with my background there are some things Mike says that are way over my head - knowledge just seems to ooze out of him - and that's not his 'secret' stuff such as his own port alignment, and how the PRC crossover works.  But it works - his crossovers are the best I have heard and his port alignment is the only ported design I have head I really like - mostly I prefer transmission line (which are hard to find).   Mikes ported designs sound like transmission line to me - how he does it beats me.  The only snippet he let slip one day - is - most textbooks and other designers have got it wrong.

 

I was at Caxton Audio one day and David (the owner) said to me - Bill you know Mike.  I said - yes - but that's not exactly hard - many customers do.  The in whispers - why do his speakers sound so good.   I said - no secret.    Well what is it?  From many many years of experience he has learnt a lot - things other designers may not even know.  Somehow that didn't satisfy him.

 

There is also another secret.   Never, ever skip on what you use inside a speaker.  He always uses low gauge air coiled inductors and at least Erse capacitors.  You may think any decent manufacturer would do that.  But having seen the insides of some very famous speakers I will not name that cant be said of many, or perhaps even most speakers.   

 

And no - I am not speaking of B&W (people know I am often critical of that very famous brand) - many years ago they did but these days use air cored inductors and good capacitors like Mundorf.

 

Thanks

Bill

Knowing how many hours in the average day Mike works, those 4 decades? of experience might equal a lot more in normal person terms :thumb:

 

I really don't know how he does it :huh: maybe a Red in the evening helps ;)

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