MW16P-4 vs MW16P-8 & TW29R vs SB29RDC-C000-4

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I'm just starting my first design/build journey and trying to absorb as much as I can. There is a lot of experience and knowledge on this forum so can I pick your brains on a few things?

I want to start with a pair of small, high quality loudpeakers, but with my current state of ignorance in mind I'll need a fall-back plan. So I am thinking of starting with an active design for the flexibility to learn but use quality drivers that are used in existing, well-respected kits with properly designed passive crossovers. If things don't work out with my own design/development for some reason(s) I can use the known design including passive crossover - even modifying or rebuilding the enclosures if necessary.

The drivers being considered are Satori MW16P and TW29R which are used in the Kairos and Adolphos kits (Meniscus/Jeff Bagby) and the Ara kit (SB Acoustics)

Question #1: It appears the Kairos/Adolphos uses the MW16P-8 and the Ara uses the MW16P-4. Any opinions on which direction might be better?

Question #2: The tweeter "intended" to go with the MW16P in these kits is the TW29R but given the great similarity of this tweeter to the SB29RDC, would the latter be a reasonable substitute to keep costs down? I think I'll notice obvious differences between the Satori and another midwoofer but for me the differences between the Satori and the companion SB series tweeter are likely to be subtle or non-existent.

Thanks for your thoughts!
 
In general, if your amplifier easily drives a 4-ohm load, the 4-ohm MW16P-4 will give you greater dynamics than the 8-ohm version. You will also get superior sound from your tweeter because it does not require extra resistors in the signal path for 8-ohm compatibility.

A 4-ohm MW16P-4 can be used in the slanted-baffle SB_Acoustics ARA, if you want to experiment with a free passive crossover.
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TW29R-4 tweeter.... you can swap the lower cost SB29RDC-4 tweeter with little sonic difference. Measurements from serveral websites prove this.
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With DSP you can use a flat baffle and insert a delay function. Genius Troels Gavensan has construction an excellent low diffraction cabinet in the Illuminator Monitor website. Simple cuts.. just two compound angle bevels. If you already have the DSP + amps, you could ONLY build this cabinet and ONLY invest in DSP.
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If your amplifier can only drive an 8-ohm MW16P-8, I would recommend building JUST the Illuminator Monitor cabinet and ONLY investing time on learing how to create a DSP crossover. ALWAYS FORWARD
 

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In general, if your amplifier easily drives a 4-ohm load, the 4-ohm MW16P-4 will give you greater dynamics than the 8-ohm version. You will also get superior sound from your tweeter because it does not require extra resistors in the signal path for 8-ohm compatibility.

A 4-ohm MW16P-4 can be used in the slanted-baffle SB_Acoustics ARA, if you want to experiment with a free passive crossover.
=====
TW29R-4 tweeter.... you can swap the lower cost SB29RDC-4 tweeter with little sonic difference. Measurements from serveral websites prove this.
======
With DSP you can use a flat baffle and insert a delay function. Genius Troels Gavensan has construction an excellent low diffraction cabinet in the Illuminator Monitor website. Simple cuts.. just two compound angle bevels. If you already have the DSP + amps, you could ONLY build this cabinet and ONLY invest in DSP.
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If your amplifier can only drive an 8-ohm MW16P-8, I would recommend building JUST the Illuminator Monitor cabinet and ONLY investing time on learing how to create a DSP crossover. ALWAYS FORWARD

Thanks, LineSource!

That Illuminator cabinet baffle looks functional and attractive. I was playing around with baffle designs and to this point had come up with the items pictured. The one on the left is flat with beveled edges for an active design with DSP and the one on the right has a .75" (19mm) step to bring the midwoofer forward similar to the amount of offset obtained with the Ara slanted baffle. I think this would make it suitable for the Ara passive crossover from a phase alignment viewpoint. But perhaps it will sound slightly bright on a stepped baffle with the tweeter being on axis to the listener if I am understanding this correctly. :)

It would be simpler to make the flat baffle and I may never resort to a passive crossover. I can make a flat and a stepped baffle and compare them too. I have amps but have not obtained a DSP (miniDSP 2X4HD) yet.

Glad to hear confirmation on my thoughts regarding the tweeter substitution.

I was planning on re-purposing a Hafler DH-200 for the LF drivers. I recently got this amplifier going again after discovering a resistor had failed open. If memory serves, this is a robust amplifier that can handle load impedances as low as 2 Ohms.
 

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I have amps but have not obtained a DSP (miniDSP 2X4HD) yet.

I was planning on re-purposing a Hafler DH-200 for the LF drivers. If memory serves, this is a robust amplifier that can handle load impedances as low as 2 Ohms.


1) Hafler DH-200 datasheet confirms very safe 4-ohm operation. Unless you plan to use other amps, the 4-ohm MW16P-4 should have some sonic advantages.
2) Medium quality passive L-R-C for the ARA will cost about 2 x $65 = $130 for the pair. If you do not have a junk box of crossover parts, purchasing just a $250 MiniDSP looks like a reasonable incremental cost. Skip a passive crossover.
3) MiniDSP supports the time delay required to compensate for the tweeter - midrange offset difference. A flat baffle will perform best.
4) DSP cannot remove cabinet edge diffraction distortion. From your cabinet CAD drawings you appear to have very good wood working skills and can cut/route the edge bevels or rounds required to reduce diffraction. Edge bevels seem easier than spending $150 for a 1.5" radius quarter round bit for your router.
 

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2) Medium quality passive L-R-C for the ARA will cost about 2 x $65 = $130 for the pair. If you do not have a junk box of crossover parts, purchasing just a $250 MiniDSP looks like a reasonable incremental cost. Skip a passive crossover.

The passive crossover from a known design is only a backup plan if things go awry. Hopefully they don't go awry. :)

BTW. The baffle width (8.5 - 9.0") and tweeter position in the CAD layouts currently mimics the Kairos. The Ara has a narrower baffle (7.5") but is asymmetrically faceted. I'm not sure how that affects diffraction but the baffle steps for the two will be different which will affect the location of the shelf in the crossover if I understand correctly.

3) MiniDSP supports the time delay required to compensate for the tweeter - midrange offset difference. A flat baffle will perform best.

Yes, I think I'll start with a flat baffle. I can make another if necessary...

4) DSP cannot remove cabinet edge diffraction distortion. From your cabinet CAD drawings you appear to have very good wood working skills and can cut/route the edge bevels or rounds required to reduce diffraction. Edge bevels seem easier than spending $150 for a 1.5" radius quarter round bit for your router.

I considered using a roundover bit. A 1.5" radius bit scares me because of its overall diameter and its cost. I think I'll stick with chamfers.

How big do the chamfers need to be? The bigger the better I suppose. They are currently about 0.75" (19mm).
 
Simply not true! SATORI TW29RN-B is way better than the "standard" SB29 ring dome. And the standard SB29 is good as is. It is not a little sonic difference.

Can the implied large sonic difference be described quantitatively or qualitatively? Like LineSource, I have found references that indicate subtle differences and areas where the Satori is slightly better, but I haven't been able to find any large differences. And in my case, if the differences are at higher frequencies then I won't be able to hear them.
 
Disagree, i have both tweeters side by side and similar crossover points and slopes, the Satori is always preferred by all listeners and the difference to me is rather huge and more than justifies the price difference. :D

Can the implied large sonic difference be described quantitatively or qualitatively? Like LineSource, I have found references that indicate subtle differences and areas where the Satori is slightly better, but I haven't been able to find any large differences. And in my case, if the differences are at higher frequencies then I won't be able to hear them.
 
"Both tweeters have very similar frequency response. The TW29R-B tweeter has a more linear and extended frequency response above 15kHz. This is probably due to the slightly different shape of the face-plate."
www.audioexcite.com >> Blog Archive >> SB Acoustics SB29RDC vs. Satori TW29R-B
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The Genius engineers at SB_Acoustics have made sonic improvements in the $122 Satori TW29R over the $51 SB29RDC which can both be measured and heard under the correct conditions. The SPL and impedance measurement data show minor differences, but also support enough compatibility to swap tweeters in most designs.

With a limited budget, many will spend the extra 2* $70 difference for Satori midranges, or for MiniDSP over passive crossovers.
 

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I see there is some disagreement on whether or not the TW29R is worth 2.7X the price.
I could start with the SB29RDC and upgrade later. I'm trying to stick within a spouse-approved budget. I don't have to tell you how critically important that is.

I have been in contact with Solen and they can provide all the parts to make an Ara equivalent passive crossover as backup. They suggest that to substitute the SB28RDC will require small changes to some resistor values to address a small difference in sensitivity. But optimistically this will all be moot.

So at this point I'm looking at obtaining the following:

2 X SB29RDC-C000-4
2 X MW16P-4
2 X 91mfd polypropylene cap (tweeter protection with 450Hz F3)
2" dia port hardware (vented design)
miniDSP 2X4HD for active crossover/DSP
UMIK-1 & REW for FR measurement

Last chance to talk me out of it. :)

Is it worth accommodating conversion to a sealed box design?

Is it worth investing in the DATS test system to optimize designs and check components?
 
Even though the tw29r and sb29rdc measure extremely similarly in frequency response and impedance, they can still sound different. The distortion measurements on audioexcite.com show a bit of a difference between the teo units at 95 dB - half an order of magnitude higher 3rd order on the sb29rdc than the tw29r for a large portion of the range. Is it worth the difference? That's up to you.

Sb29rdc
Tw29r
 
Satori tweeter can cross lower and just sound more clean, open, more 'snappy' on transients etc. On top of that also more extended and 'even' top end. I had the same hesitations about it would be better. It is :)

No need for that DAT measuring thingy - save the money and buy the Neo Satori tweeter.

Have you considered the Satori 7 1/2 midwoofers ?
 
Even though the tw29r and sb29rdc measure extremely similarly in frequency response and impedance, they can still sound different. The distortion measurements on audioexcite.com show a bit of a difference between the teo units at 95 dB - half an order of magnitude higher 3rd order on the sb29rdc than the tw29r for a large portion of the range. Is it worth the difference? That's up to you.

Sb29rdc
Tw29r

I have read elsewhere that others claim the high frequencies to be particularly clean with good transients with the TW29R. Jeff Bagby's write up on his own Kairos design would be an example.
 
Satori tweeter can cross lower and just sound more clean, open, more 'snappy' on transients etc. On top of that also more extended and 'even' top end. I had the same hesitations about it would be better. It is :)

Were you able to do a direct A-B comparison?

No need for that DAT measuring thingy - save the money and buy the Neo Satori tweeter.

The rare earth magnet version of that tweeter is further out of my price range! But maybe I could swing the regular TW29R somehow...

Have you considered the Satori 7 1/2 midwoofers ?

I have not considered the larger midwoofers. I don't think I need them. I tend not to listen to music very loud and I have a pair of subwoofers. From what I have read, it might also be more difficult to maintain a good power response/DI.
 
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Hi,
About the port, you could use other shape ( rectangular) or other technique to fit your needs ( make some square then cut disc using a router).
Anyway you will probably need to 'tune' the port for length in your room.
You can do that using a paper sheet rolled on itself to determine definitive length for circular port, or adding a removable 'cover' for a rectangle one.

You talk about sub you already own. This make your comment about having the possibility to run closed box a valuable option. Reflex can have difficult group delay properties to have an easy integration of crossover, it will depend of alignement you choose as target ( bessel is probably better in that respect but it may require bigger volume for box).
Closed may be easier to integrate. As you'll run active dsp filtering you could even use a Linkwitz Transform to match to your sub if needed. Trade off are efficiency for lowend ( given a fixed box volume) but it could do the trick ( i've done this on my own speakers mid to lower xover point to woofer. Lost some overall spl gained ( marginaly) better directivity behavior).
 
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Hi,
About the port, you could use other shape ( rectangular) or other technique to fit your needs ( make some square then cut disc using a router).
Anyway you will probably need to 'tune' the port for length in your room.
You can do that using a paper sheet rolled on itself to determine definitive length for circular port, or adding a removable 'cover' for a rectangle one.

I have fabricated vents before for subwoofers but was hoping to avoid that. I wonder what the ID is of shop vac wand? Might only be 2-1/4". Flared exits could be made from wood for any sort of tube I could find near 2-1/2" ID.

You talk about sub you already own. This make your comment about having the possibility to run closed box a valuable option. Reflex can have difficult group delay properties to have an easy integration of crossover, it will depend of alignement you choose as target ( bessel is probably better in that respect but it may require bigger volume for box).

Closed may be easier to integrate. As you'll run active dsp filtering you could even use a Linkwitz Transform to match to your sub if needed. Trade off are efficiency for lowend ( given a fixed box volume) but it could do the trick ( i've done this on my own speakers mid to lower xover point to woofer. Lost some overall spl gained ( marginaly) better directivity behavior).

Hmmm. I hadn't put any thought yet into using the DSP on the 2-way active to help integrate on the low end with the subs. So your suggestion is to use the DSP to perhaps extend the LF a bit with a closed box design to avoid the phase issues a port would introduce? Interesting...
 
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Hi,
Yes a dsp can do many things other than pure filtering duties.
My point about your case is that in the case your vented 2 ways is difficult to cross to your sub one possible option is to close the port and use an LT to make things easier.
My comment about low end extension is a worst case scenario: you may (or not!) need to increase extension in the low end then in that case the trade off are the one i stated earlier ( this was what i faced for my own needs) BUT the point of an LT is to change the whole system ( closed box AND driver) fc and Q.
So it works both ways, you could use it to make fc higher with a different Q. In this case there is no trade off and you may gain in overall spl ( to the xmax limit or power dissipation of the driver).
As well it can open some possibilities to use the acoustical properties of the box+driver combo to achieve a target of high pass defined.
Example you could make a Samuel Harsch filter solution for the high pass required just using the LT to have the butterworth 2pole target.
In fact it open many possibilities and different options ( it could help in a 1 pole filter too, trying to compensate for the behavior of the driver outside of its intended usable range then include a filter to have a theorical text book response... as long as you don't try to compensate things which are non minimal phase( as break up of membrane, some diffraction, geometry related issues,...) it works quite well ime.
But for your specific case you'll have to contemplate what works for you in your room and for your expectations...
All that to say dsp filter is quite flexible and it can open ways you haven't thought about...
 
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