Which woofer ?

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I am a n00b when it comes to building my own loudspeakers and everyone has to start somewhere. I am down to a few woofers that I find interesting, but I am battling which one to settle for. So I was thinking - stupidly :D - to reach our for a few comments and perhaps some clarification on which one signify better quality.

Transients, aka "fast bass" is important since reproduction of the music is important.
Sd as this is connected to SPL.
Qts since this dictates sealed or vented and I would like a vented box so achieve better low end extension.

To give you a better image of what I am want to build, here is a simplified system explanation:

I was initially going to build a 3-way featuring a hard dome tweeter, 5" midrange and 2x 8" woofers. But this turns out to be too wide since I have some space limitations. Therefore, I will opt for a 3x 6.5" woofer solution to maintain a fairly decent bass area (Sd). And it is here I am struggling a bit on which one to choose.

The selection - so far - consist of:

SB Acoustics SB17MFC35-4 - PP Cone.
Monacor SPH-6M - PP Cone
Faital Pro 6FE100 - Poly Cone
Peerless HDS-930990 - Glass Fiber Cone
SS 18W/4434G00 - Glass Fiber Cone.

The price is fairly similar with exception for the Faital Pro which is the cheaper one and also has the highest Qts of 0.56, suggesting sealed enclosure. But that alone does not mean it performs less or better (I think ?)
The Monacor SPH-6M has the lowest VAS value with only 17.6 liters, meaning it is the stiffest of the bunch ? the Qts is only 0.3 for this one.

In terms of Sd, Peerless with its 143.1 cm^2 and Faital Pro with its 143 cm^3 will produce the over all largest combined area.

So here I am, stuck in "which woofer" to go for ...
 
What amplifier are you intend to use?

Don't be mind-constrained, see that you can also place woofers at the sides of the enclosure. Use large Vd set of drivers, 2x 8-inch or 1x 12-inch per side as a minimum. Keep impedance low in order to preserve good voltage sensitivity of the system. You can tune it using passive radiator in order to avoid port resonances and air turbulence noise.

SB Acoustics :: 12" SB34SWPL76-4

This is one hell'a of subwoofer. Place it at the side of the box and it retains standard baffle width of 8-inches. This beast plays definitive bass notes in compact, PR-tuned box up to 200-250 Hz, where usually 6.5-inch midrange driver takes over control. If you don't want passive radiator you can put (long!) port at the bottom of the enclosure in order to enforce bass response using boundary coupling.

Only large and robust drivers with plenty of Vd can deliver sensation of "fast bass" if properly tuned.
 
If you are baffle width constrained and don't mind 6.5 inch driver overload take a look at this 6 * 6.5 per side design
Peerless 5 - A 2.5 way - MTMMM

F3 is only 54 Hz so depends on your loudness Vs extension goals.

PS I have not built or heard that design.
Looking at that thread, I can't easily get that Peerless driver, but it does have some really nice price vs performance relationship. On the other hand, the Elsinore project which use the SB NRX woofer is interesting. I chose the SB MFC driver of interest but the NRX has also been / is on the list.

The Elsinore project has a very nice freq.response curve. I have attached the response curve.

But I have a different midrange and tweeters in mind. Both the NRX and MFC woofers are fairly similar. The only question I have if we compare them to the Monacor SPH-6M is the much much lower VAS for the Monacor. I wonder how this one compare to the SB's.

Monacor SPH-6M
 

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What amplifier are you intend to use?.
I think I will go for the Marantz PM-6005 UK Edition - also the NAD C368 or 388 is of interest further down the road.


The reason I will go for 3 x 6.5" or 3 x 6" (depend a bit on which driver I end up with) is space restraint. The room is roughly 30 m^2 and can't be changed. Subs are more or less out of the question for now :)
 
By far the most difficult part of loudspeaker design is the crossover. What are you going to use to design the crossover?

Assuming this is your first design I'd start with a 2-way because a 3-way is a hell of a lot more difficult for the novice. You could convert your 2-way to a 3-way when you gain more experience.
 
By far the most difficult part of loudspeaker design is the crossover. What are you going to use to design the crossover?

Assuming this is your first design I'd start with a 2-way because a 3-way is a hell of a lot more difficult for the novice. You could convert your 2-way to a 3-way when you gain more experience.
1. For the crossover, besides measurements, I will either use Leap or LspCAD and finally my ears, and I am ofc thinking about model / material which the cap's are made from.

2. Its actually fairly "simple" because I will use dedicated space for the midrange (and tweeter), meaning they will live inside their own cabinet inside the main cabinet, so, one can look at that as the 2-way which will be dealt with kinda separate. - Decoupling is very important. Meaning, the woofer section will be dealt with separately and the final touch come when the sum of all 3 stages is viewed as one :)
 
Just to clear it up. When people propose 8-12 inch sidemounted woofers for low bass duty, you can still make a very narrow speaker. So are you also very limited about depth of the speaker?
Depth is not as sensitive, I would say I have roughly 350mm is what I can accept.

Come to think of it, Audio Physics Structure (by Joachim Gerhard) (inspiration) is of interest and, I could certainly take that route. It fits my goal in terms of size etc :) so thanks for the reminder. And I have settled for a woofer. The SB SB17MFC35-4 (6 in) PP, in combination with SB SB15NBAC30-4 (5 in) alu midrange. Regarding tweeter, well that is a work in progress, there are several of interest, including 2 from SEAS, Accuton (C25-6-158) and Viawave.


But going for a side-firing LF driver (20-80 Hz) reshape the entire project and we instead have a 4-way, which introduce some benefits if one consider some octave rules that exist.

So thank you.
 
Out of your original choices I'd pick the Faital.
I have used the 5" version.
Previously my favourite 5 was the Audax aerogel job but the little Faital is the better driver in every respect at 1/3 of the price.

Btw the Faitals Vas is 14.1L, lower than the Monacor.
Thanks for the input, but I just made my choice as you can see from the post above this one. I will keep the Faital Pro in mind for other projects because it is indeed a very nice driver.
 
Its actually fairly "simple" because I will use dedicated space for the midrange (and tweeter), meaning they will live inside their own cabinet inside the main cabinet, so, one can look at that as the 2-way which will be dealt with kinda separate. - Decoupling is very important. Meaning, the woofer section will be dealt with separately and the final touch come when the sum of all 3 stages is viewed as one
Physically decoupling the mid does nothing in simplifying the crossover, you still have to design a 3-way, and this is much more complex than a 2-way.

The SB SB17MFC35-4 (6 in) PP, in combination with SB SB15NBAC30-4 (5 in) alu midrange.
Very strange combination IMHO. The strength of the SB PP driver is the smooth breakup that can lead to a simple 2-way at around 2-2.5KHz. The 5" alu, although a good driver, can't be crossed over much higher. For a 3-way I'd opt for a 8", if width is a constraint have a look at a truncated frame driver like the Peerless 830869.

Ralf
 
giralfino: Its not strange. I like hard dome drivers when they are good. And one of the best midrange drivers I've ever heard was based upon ScanSpeak Illuminator. I also enjoy nice hard dome tweeters. But its not for everyone, so no meaning in going into lengthy debates here :)

I want and need for the midrange area to be crisp, detailed with good transients. A Poly or paper cone cannot deliver that which hard domes can. Saying that, I realize that hard domes often have issues with cone breakup, so a good tweeter that can work fairly low is required to balance out any issues. Also, poly and paper are more forgiving, so... a combination of materials can actually produce a well balanced system.
But this has no meaning if someone has strong opinion that woofers and midranges should be made of paper and tweeters should be made of silk aka soft domes.


Guerilla pointed me towards low end extension via adding a side firing woofer (8-10 in) in combination with a front firing 6-6.5 in, so I extended that and are now looking at a 4-way system, which is actually not a bad idea since I can model the system to work with in a 3 octave per driver situation. I kinda like that :)
 
giralfino: Its not strange. I like hard dome drivers when they are good. And one of the best midrange drivers I've ever heard was based upon ScanSpeak Illuminator. I also enjoy nice hard dome tweeters. But its not for everyone, so no meaning in going into lengthy debates here :)

I want and need for the midrange area to be crisp, detailed with good transients. A Poly or paper cone cannot deliver that which hard domes can. Saying that, I realize that hard domes often have issues with cone breakup, so a good tweeter that can work fairly low is required to balance out any issues. Also, poly and paper are more forgiving, so... a combination of materials can actually produce a well balanced system.
But this has no meaning if someone has strong opinion that woofers and midranges should be made of paper and tweeters should be made of silk aka soft domes.


Guerilla pointed me towards low end extension via adding a side firing woofer (8-10 in) in combination with a front firing 6-6.5 in, so I extended that and are now looking at a 4-way system, which is actually not a bad idea since I can model the system to work with in a 3 octave per driver situation. I kinda like that :)
 
Guerilla pointed me towards low end extension via adding a side firing woofer (8-10 in) in combination with a front firing 6-6.5 in, so I extended that and are now looking at a 4-way system, which is actually not a bad idea since I can model the system to work with in a 3 octave per driver situation. I kinda like that :)


-that's a much better plan. ;)


For the mid transition:

SBAcoustics SB15MFC30-8

scroll down a little:

Zaph|Audio

It's a cleaner midrange and has better performance off-axis higher in freq. for an easier transition to the tweeter relative to the 6" version. It also has enough low-end performance to be used without a high-pass section (that would be costly).

While it's poly, it's "mineral" loaded - sort of like a poly-damped metal membrane (..which is not dissimilar to Audio Technology's drivers).

If you can stretch your funds, the 10" Discovery from Scan Speak would make a good side-firing, baffle-step compensation woofer:

Some speaker driver measurements...
 
-that's a much better plan. ;)

For the mid transition: SBAcoustics SB15MFC30-8
I have a few comments, so lets break it up in sections.

1. That is a nice performance I must say. The breakup happens roughly at 2.5 kHz. But take a look at the 4 ohm version. Its not presenting any real problems until 3-3.5 kHz, the Qts is a nice 0.28 compared to the 8 ohm which is Qts 0.37. Its like two different drivers... weird. But to my eye's, the 4 ohm version is a better performer, perhaps on par with some Accuton's and as you say which is similar to Audio Technology's drivers.

SB link for the 4 ohm verison: 5" SB15MFC30-4 :: SB Acoustics

2. That SS 10" woofer is impressive, and its an alu cone which I like :) and the price is very much doable. So thanks for that input.

3. I am very much leaning towards the Viawave GRT 145 tweeter.

4. Since I am using the Audio Physic Structure / Codex as inspiration, I figured out that the mid-woofer is a 7" alu driver from Wavecore, and 7" in combination with alu cone sounds like a nice combo. The only downside - perhaps - is the 85 dB in sensitivity, but on the other hand, at 200 Hz, the SB also dip down to roughly 85-86 dB ... a possible match there perhaps.. hmm

Wavecor: SW182BD03_04
 
1. That is a nice performance I must say. The breakup happens roughly at 2.5 kHz.


5.7 kHz for the one resonant ridge, slightly higher for the 4 ohm:

www.audioexcite.com >> SB Acoustics SB15MFC30-4

-it's still not exactly a "bell mode" resonance with a lot of trailing resonances near the average (at freq.s below that). However you will have to deal with it, but that's true for most designs.


Note the off-axis response. With this driver (either 4 or 8 ohm) you are good to about 3 kHz to match with your tweeter, which is something you generally won't get with a larger driver.


-of course the measured performance is not exactly what SB claims (..as seen in the link above). I'd peg the average eff. (1 watt 1 meter) at about 88 db.


Up to you though, it's just a suggestion. ;)


The Viawave 145 is very nice and should work well with a cross-over near 2.5 kHz.. and not badly at 2 kHz with the right high-pass. (..maybe even 1.7 kHz if it's a very steep filter). If you are willing to have a steep high-pass then a larger driver is possible.


The Wavecore isn't efficient enough. :eek: It really needs to be a few db more than the midbass driver it's summing with to compensate for baffle loss. The Scan can get that with a smaller cabinet (..boosting that 80-300 Hz region a bit), at the expense of lower freq. extension.
 
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