Zaph's sujested Peerless 830656 & Seas DXT MMTMM design
Good evening all,
I am hoping to start an investigation that will culminate into something myself and others will find of interest.
In one of Zaph's recent posts he describes the MMTMM senario using Peerless 830656 woofers and Seas DXT tweeter in a 2.5 way configuration. A sort of a poor mans "LGT" I guess.
Anyway not having any great software packages and the experience to completely design such a speaker (Yes Zaph cross overs and BSC etc etc scare the hell out of me).
Thats why my first speaker was Tony Gee's "Solo 206". But eventually I plucked up the courage to build Zaph's "ZBM4" bargain mini. It's a great little speaker but since I started using it for my PC sound the kids won't let me take them away and I am left wanting for speakers for my lonely Leach amp. (206's dont cut it sorry Tony)
Anyway in WinISD beta I have come up with two woofers in a 36 litre vented box and a tuning frequency of 45Hz. Box internal measurements of width 150mm height 600mm and depth 400mm.
There will be two of these boxes on top of each other and wedged in between will be the tweeter and hopefully space for the Xover. I believe these dimenssions come out somewhere close to Zaph's 50 inch mark.
Questions?
Am I better to stick with a straight baffle or design with angled woofers toward a listening position as in LGT.
My room has 8 foot ceilings so the bottom woofers will be closer to floor (carpeted). Should this be taken into account when designing cabinet or can we fix with Xover? Ceiling hard surface so maybe reflections will be even anyway? Distance and carpet doing the job anyway?
Anyway hopefully the guru's will be willing participants and some time down the track I and others will have something special in the lounge much to our partners delight!!! He He!!
Ian
Good evening all,
I am hoping to start an investigation that will culminate into something myself and others will find of interest.
In one of Zaph's recent posts he describes the MMTMM senario using Peerless 830656 woofers and Seas DXT tweeter in a 2.5 way configuration. A sort of a poor mans "LGT" I guess.
Anyway not having any great software packages and the experience to completely design such a speaker (Yes Zaph cross overs and BSC etc etc scare the hell out of me).
Thats why my first speaker was Tony Gee's "Solo 206". But eventually I plucked up the courage to build Zaph's "ZBM4" bargain mini. It's a great little speaker but since I started using it for my PC sound the kids won't let me take them away and I am left wanting for speakers for my lonely Leach amp. (206's dont cut it sorry Tony)
Anyway in WinISD beta I have come up with two woofers in a 36 litre vented box and a tuning frequency of 45Hz. Box internal measurements of width 150mm height 600mm and depth 400mm.
There will be two of these boxes on top of each other and wedged in between will be the tweeter and hopefully space for the Xover. I believe these dimenssions come out somewhere close to Zaph's 50 inch mark.
Questions?
Am I better to stick with a straight baffle or design with angled woofers toward a listening position as in LGT.
My room has 8 foot ceilings so the bottom woofers will be closer to floor (carpeted). Should this be taken into account when designing cabinet or can we fix with Xover? Ceiling hard surface so maybe reflections will be even anyway? Distance and carpet doing the job anyway?
Anyway hopefully the guru's will be willing participants and some time down the track I and others will have something special in the lounge much to our partners delight!!! He He!!
Ian
According to Zaph : Qts = 0.51, Vas = 9.6L, Fs = 53Hz
http://www.zaphaudio.com/blog.html Nov 29 Vertical Polar Response
Hi,
Putting drivers in boxes where the box volume exceeds the drivers
Vas is not a good idea, basically for that volume there is usually a
better driver choice. 18L for a 9L Vas driver is not good practise.
18L vented is more typical for a 6.5" driver.
Qts = 0.51 usually means sealed, but is on the cusp of being ventable,
but this means a big box or a unusual more compact vented alignment.
WinISDbeta is OK for quick sims but you need something more
accurate like Unibox for simulating anything your going to build.
I'm not saying you cannot build these boxes, but they will be big.
72L a side in a tall (50") and slim (7") form = loads of wood / mdf.
/sreten.
http://www.zaphaudio.com/blog.html Nov 29 Vertical Polar Response
Hi,
Putting drivers in boxes where the box volume exceeds the drivers
Vas is not a good idea, basically for that volume there is usually a
better driver choice. 18L for a 9L Vas driver is not good practise.
18L vented is more typical for a 6.5" driver.
Qts = 0.51 usually means sealed, but is on the cusp of being ventable,
but this means a big box or a unusual more compact vented alignment.
WinISDbeta is OK for quick sims but you need something more
accurate like Unibox for simulating anything your going to build.
I'm not saying you cannot build these boxes, but they will be big.
72L a side in a tall (50") and slim (7") form = loads of wood / mdf.
/sreten.Sreten,
How would you characterise the differences between Winisd & Unibox? I have both but usually use Winisd because I'm too impatient to wait for Excel to start up on my clunky computer. (and it's a bit easier to compare multiple sims)
IIRC, in the past I got similar results trying the same thing on both.
Cheers,
Pete McK
How would you characterise the differences between Winisd & Unibox? I have both but usually use Winisd because I'm too impatient to wait for Excel to start up on my clunky computer. (and it's a bit easier to compare multiple sims)
IIRC, in the past I got similar results trying the same thing on both.
Cheers,
Pete McK
Hi Sreten and Pete McK,
Sreten I have taken on board what you have said and tried the set up with Uinbox. It works great and a lot more detail also.
I came up again though with 4 x drivers in 70 to 75 litres. Box size doen't worry me honestly. (The wife well we will see)
Hopefully I will be able to attach these files and pictures so you all can see and guide me through the issues.
Firstly the vented box of 75 liters looks good but I also like the passive radiator as well.
I am not sure if the PR is for just one driver or not and if it would work by placing it on the back of the cabinet radiating toward the walls.
In both cases I seem to be strugling with cone excursion. It appears that I can limit it with damping. Any idea's?
I am trying to sort out this drawing thing on the PC so I can post an image etc Probably going to go through a big learning curve though so may take some time.
Sreten I have taken on board what you have said and tried the set up with Uinbox. It works great and a lot more detail also.
I came up again though with 4 x drivers in 70 to 75 litres. Box size doen't worry me honestly. (The wife well we will see)
Hopefully I will be able to attach these files and pictures so you all can see and guide me through the issues.
Firstly the vented box of 75 liters looks good but I also like the passive radiator as well.
I am not sure if the PR is for just one driver or not and if it would work by placing it on the back of the cabinet radiating toward the walls.
In both cases I seem to be strugling with cone excursion. It appears that I can limit it with damping. Any idea's?
I am trying to sort out this drawing thing on the PC so I can post an image etc Probably going to go through a big learning curve though so may take some time.
Attachments
PeteMcK said:
Hi,
I use WinISDbeta with just Fs, Qts, and Vas to do the basic
maths. So you get e.g. the effective box volume required.
The biggest differences are likely sealed boxes and small boxes.
I've hardly used Unibox, for excursion etc I use WinISDpro.
Cross checking with another sim seems to me a good idea.
/sreten.Hi,
Having thoroughly perused Zaphs post I can see what he is getting
at and why he would like to build it to see what it sounds like.
However there is nothing "wrong" with the dispersion of the MT.
One could argue it is the "ideal" combination of axial and power
response and you would be hard pushed to argue against this.
More directional designs are interesting. In a simplistic nutshell
it is like sitting nearer to the speakers and is related to the
http://www.pispeakers.com/ssdm_99.pdf
"critical distance", see section 5.14 in the above. Depending
on the room size, shape, seating arrangements and the users
listening preference (most non-critical listeners prefer to be in
the reverberant field where the levels are substantially equal)
manipulation of directivity may or may not be beneficial.
What is known (according to Floyd Toole) is most listeners
prefer the sound of small accurate speakers in the far field.
That is small wide dispersion speakers appear to be further
away from you, the downside for some listeners is that this
sound is not "direct" enough, more "in the face" is wanted.
I'm not saying do not build them, I am saying they will
be "different" and not always better than the simple MT.
Regarding your boxes around 6 to 8 L per driver well stuffed
would suit use with additional subwoofers and a HT amplifier.
Vented with no subwoofers I'd recommend around 14L per
driver with the vent tuned to 38Hz. As they are relatively
large boxes and the tuning is not that low the use of
passive radiators should not be necessary.
I do not know what PR's you have in mind, side mounted ?
/sreten.
Having thoroughly perused Zaphs post I can see what he is getting
at and why he would like to build it to see what it sounds like.
However there is nothing "wrong" with the dispersion of the MT.
One could argue it is the "ideal" combination of axial and power
response and you would be hard pushed to argue against this.
More directional designs are interesting. In a simplistic nutshell
it is like sitting nearer to the speakers and is related to the
http://www.pispeakers.com/ssdm_99.pdf
"critical distance", see section 5.14 in the above. Depending
on the room size, shape, seating arrangements and the users
listening preference (most non-critical listeners prefer to be in
the reverberant field where the levels are substantially equal)
manipulation of directivity may or may not be beneficial.
What is known (according to Floyd Toole) is most listeners
prefer the sound of small accurate speakers in the far field.
That is small wide dispersion speakers appear to be further
away from you, the downside for some listeners is that this
sound is not "direct" enough, more "in the face" is wanted.
I'm not saying do not build them, I am saying they will
be "different" and not always better than the simple MT.
Regarding your boxes around 6 to 8 L per driver well stuffed
would suit use with additional subwoofers and a HT amplifier.
Vented with no subwoofers I'd recommend around 14L per
driver with the vent tuned to 38Hz. As they are relatively
large boxes and the tuning is not that low the use of
passive radiators should not be necessary.
I do not know what PR's you have in mind, side mounted ?
/sreten.- Status
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