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jkn

Satori 2018

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The one thing that I think of looking at this due to the modular set up that the distance between drivers is likely contributing to that impression.

Even with digital delays which makes it much easier it's never 100% and keeping the distances as close as possible always sounds better IMO

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2 hours ago, Wozza_Lee said:

The one thing that I think of looking at this due to the modular set up that the distance between drivers is likely contributing to that impression.

Yes, the driver spacing is not ideal.... even for such a low crossover point (1250Hz), although that helps.

 

2 hours ago, Wozza_Lee said:

Even with digital delays

Getting the time alignment perfected is a good thing.... and solves some obvious problems.

 

But time alignment (no matter passive or active) does not fix the "lobing" in the frequency response between non-coincident drivers. 

 

In theory a MTM can improve the lobing vs a TM... but in practise, things are more complex.

 

 

It is extremely common in speaker design that simple/basic things (like moving the drivers together) are more important (x1000), than "fancy" things like seperate box that run counter to important goals.

 

But separate, heavy, isolated boxes .... while likely in general worth little performance .... are fun, and cool, and an important part of any DIY project  ;) 

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Pretty sure he mentioned that he is crossing to the Tweeter at 2k?

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On 19/08/2019 at 11:14 AM, davewantsmoore said:

Yes, the MTM needs to be designed very carefully to work... otherwise it will be overall a negative.

I kinda becomes a difficult proposition as to whether to use a steep or shallow rolloff in the crossover region.   Like I said, I'm not surpised it sounded better.

I fully agree I have been playing with MTM for years and I could never get to work 100% as soon as I use MT things just work 

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9 hours ago, Wozza_Lee said:

Pretty sure he mentioned that he is crossing to the Tweeter at 2k?

I'm currently crossing the tweeters at 1350Hz (54db lineral phase slopes)

My preference with Bliesma tweeters >T34B nad T34A is between 1600-1250

 

2K I have used for SS ring radiator and SB TW29B works well

Edited by jkn

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Just a little update 

I have add the extra bass on the top the reason being is when I measure the speakers with one bass driver only = placed ON TOP I end up needing more boost>(more then 6db) I always try to stick with max 6db.... anyway in that particular position with one bass only I need it around 10db boost to get 80Hz So I decided to try the extra bass box on top and it does seams to be working well (also calibration template limits are well in+-6db.

placement_05.jpg

 

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On 19/08/2019 at 12:53 PM, Wozza_Lee said:

The one thing that I think of looking at this due to the modular set up that the distance between drivers is likely contributing to that impression.

Even with digital delays which makes it much easier it's never 100% and keeping the distances as close as possible always sounds better IMO

Fully agree one other thing I would point out is that when I measure bass drivers in my original set up SEPARATELY (one bass on the bottom the other on the top) distance around 1m apart  from sitting position to implement room EQ they both show different FR (6+6-db)so I THINK that does not help either when they are connected as one driver.  

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12 hours ago, jkn said:

I fully agree I have been playing with MTM for years and I could never get to work 100% as soon as I use MT things just work 

I have noticed a few active setups with WMTMW and they seem to end up preferring the MTM section as 2.5 way.  I think something to do with lobing/comb filtering.

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16 hours ago, jkn said:

I fully agree I have been playing with MTM for years and I could never get to work 100% as soon as I use MT things just work 

I like reasonably steep filters (eg. 24dB/octave)

 

... but when I work with MTMs I kinda tend towards a much shallower overlap in the XO region  (I still move to steep filter out of band if possible)

 

... so with a heaps steep filter ... then I'm really not surprised the MTM was not preferred.  :)

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16 hours ago, jkn said:

I'm currently crossing the tweeters at 1350Hz (54db lineral phase slopes)

My preference with Bliesma tweeters >T34B nad T34A is between 1600-1250

It's very low for these tweeters.

Do you test for distortion at your peak SPL?

16 hours ago, jkn said:

Just a little update 

I have add the extra bass on the top the reason being is when I measure the speakers with one bass driver only = placed ON TOP I end up needing more boost>(more then 6db) I always try to stick with max 6db.... 

Do not be afraid of the "EQ boost" itself.

 

The important thing is the driver excursion (ie. distortion) at your peak SPL.

 

Otherwise....   Assuming the low pass is reasonably low in Hz  (Id need to go back to check) .... then having the second driver there is of no concern (only a benefit).

 

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16 hours ago, jkn said:

Fully agree one other thing I would point out is that when I measure bass drivers in my original set up SEPARATELY (one bass on the bottom the other on the top) distance around 1m apart  from sitting position to implement room EQ they both show different FR (6+6-db)so I THINK that does not help either when they are connected as one driver.  

That will depends on what frequency you're talking about.    Assuming it's low, then it's the sum which is important. 

 

... and +6dB -6dB = 0 could be good.

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I would expect a mtm to sound better with a low order xo.

Never used one but makes sense

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3 hours ago, davewantsmoore said:

It's very low for these tweeters.

Do you test for distortion at your peak SPL?

1350 is the manufacture recommended crossover point .I have use them as low as 1150 with not any issues.    

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8 hours ago, lusk said:

I have noticed a few active setups with WMTMW and they seem to end up preferring the MTM section as 2.5 way.  I think something to do with lobing/comb filtering.

I use t own Whatmough 505 long time back and they were based on WMTMW design I did like them a lot and since then I was pressuring that design unfortunately  with no much luck 

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On 19/08/2019 at 3:23 PM, davewantsmoore said:

But separate, heavy, isolated boxes .... while likely in general worth little performance

Dave can you please elaborate this comment I do not quite understand 

Thanks

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14 hours ago, jkn said:

Dave can you please elaborate this comment I do not quite understand 

Thanks

Your seperate and thick walled boxes cause the MT drivers to be spaces apart by a certain minimum distance.

You would do better to lose the over-engineered boxes, and space the drivers closer together.   It would positively contribute to performance (the polar response) much more than the heavy boxes do.

 


I had written a whole bunch more stuff here (deleted) .... I don't want to derail your thread, or cast negative aspersions.

 

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On 23/08/2019 at 11:04 AM, davewantsmoore said:

I had written a whole bunch more stuff here (deleted) .... I don't want to derail your thread, or cast negative aspersions.

Don’t worry about derailing this thread all opinions (positive or negative) are welcome here

Still I would add that despite the max spacing between the drivers due the the design  the system sound pretty good I mean really good.Now the question is  would it be better with min spacing using different design I guess that is  something to find out in the future 

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On 23/08/2019 at 11:04 AM, davewantsmoore said:

I had written a whole bunch more stuff here (deleted) ....

Why deleted ? any link to that subject?

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As you are using digital xo maybe try changing your mid-Tweeter to 2nd order at 3k and see if you like it?

Or maybe 4th order 2500

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20 minutes ago, Wozza_Lee said:

As you are using digital xo maybe try changing your mid-Tweeter to 2nd order at 3k and see if you like it?

Or maybe 4th order 2500

Are these suggestions arbitrary or is there some reasoning for the choices here?

 

Would be good if you could outline the reasoning behind the suggestions. 

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Make sure to get plenty of off axis responses as well to get an idea of your power response and how well your crossover choices are doing.

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4 hours ago, jkn said:

the system sound pretty good I mean really good

Sure ... but removing errors in the way it reproduces sounds will only make you think it sounds even better.

 

Quote

Now the question is  would it be better with min spacing using different design I guess that is  something to find out in the future 

I would say always go for minimum spacing.... unless doing that means you have to introduce a problem somewhere else.

 

On 21/08/2019 at 5:41 PM, jkn said:

1350 is the manufacture recommended crossover point .I have use them as low as 1150 with not any issues.    

 

Yes, I see.... I was looking at the spec of the A version.

 

Wow. (The B version) looks like a NICE tweeter.... I would love to put one in a waveguide..... but OMG $$$$$  

4 hours ago, jkn said:

Why deleted ? any link to that subject?

Oh, just a little bit of a spiel about only designing the speaker on a single axis.

 

... but then I'm not sure you actually did that.   I just get that impression by the dexq charts posted.     If you choose driver spacing and crossover frequencies and slopes based on the polar response (3 dimensional) frequency response of the speaker .... it may improve a lot.

 

Anyways.... I thought twice, because I didn't want to come across as saying they were bad.

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3 hours ago, Wozza_Lee said:

As you are using digital xo maybe try changing your mid-Tweeter to 2nd order at 3k and see if you like it?
Or maybe 4th order 2500

Then.... we would have a serious issue with the spacing between drivers (too big).

 

 

 

 

I think the polars would also likely not match well  (I'd have to check out a 34mm tweeter response) ..... I'd want to keep it as low as possible in general.

 

 

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52 minutes ago, niss_man said:

Make sure to get plenty of off axis responses as well to get an idea of your power response and how well your crossover choices are doing.

Yes.   Need to take measurements at many angles.... to see if crossover choices are really working.

 

Like driver spacing mentioned earlier .... this sort of things is the fundamental to SQ.    Using $ drivers and super boxes is nice .... but this stuff matters more.

 

$50 tw done well.... will beat $600 tw with bad XO.

 

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