Need help! High output 3 or 3.5-way

[alexcd]

DIY mates, I got the bug listening to some B&W 800s and want to build another set of speakers! I'm not asking to clone them but I do want to make something that can sound great even loud. While I may use a subwoofer for movies, I don't plan on it for music. Let's call it a mid-life crisis speaker build.

Here's what I'm liking so far
Tweeter: SB29RDC-C000-4
Midrange: NE149W-04
Woofers: 2x SB29NRX75-6, SDF-250F75PR01-06, or SB Acoustics WO24P-8
FWIW, I have speakers with dual RS225-8 now and they sound fantastic but don't get as loud as I'd like.

Let's be engineers about this and be critical when needed.

I am planning to use a miniSHARC processor into 8ch of amplification to run them active and choose my crossover points, but I may want to design a passive crossover at some point and the total impedance should be around 4ohm.

Great thread but want something that really shakes the room and sounds effortless doing so.
Open Source "Tower XL" thread

 

[Tromperie]

I use the SB29s in my three way active speakers and they aren't short of bass. I'm not sure why you would go for the extra expense and nearly double box size for a 3.5 for baffle step correction when this can be handled with DSP.

 

[andy19191]

FWIW, I have speakers with dual RS225-8 now and they sound fantastic but don't get as loud as I'd like.

If you increased the RS225-8 from 8" to 10", 50% larger cone area, and kept the other parameters the same would this SPL increase be enough? Assuming not, what else needs to change to bring the SPL increase you want.

What are your constraints in terms of available power, acceptable box size, acceptable low frequency extension, price, etc...? To help answer the question would the maximum SPL, bass extension and ported box size of a pair of these 12", 8 ohm, woofers in parallel be adequate?

but I may want to design a passive crossover at some point

Suitable for a passive crossover will significantly constrain the design because the sensitivity and power handling of the midrange and woofers will need to match. This will require the sensitivity of the speaker in a room (not the driver sensitivity) and the baffle width plus midrange crossover frequency and slope to determine how the woofer and midrange sum with respect to baffle step correction.

Your current choice of midrange will not have the sensitivity, power handling or SPL output to match a pair of woofers with substantially more SPL than you current pair of Daytons.

 

[Zvu]

Forget home audio drivers. Since double rs225 doesn't meet the demands, you should be aiming for something like this:

The-Loudspeaker

 

[alexcd]

Excellent help everyone!

If you increased the RS225-8 from 8" to 10", 50% larger cone area, and kept the other parameters the same would this SPL increase be enough? Assuming not, what else needs to change to bring the SPL increase you want.

If you consider the increased X-max, the displacement is around 2x which would be OK by me.

What are your constraints in terms of available power, acceptable box size, acceptable low frequency extension, price, etc...? To help answer the question would the maximum SPL, bass extension and ported box size of a pair of these 12", 8 ohm, woofers in parallel be adequate?

hehe, I like the sound of 12"s instead of 10"s! Does this get anyone worried about running them up to a reasonable XO point for the midrange?

F3dB<30Hz so it should have plenty of output to 20Hz in-room, right?
I've been targeting 120-140L total depending on the woofer.
Price is negotiable but the drivers I listed are in the right ballpark. If we're talking about more expensive 12" woofers, I did find this one, UW1258.

Suitable for a passive crossover will significantly constrain the design because the sensitivity and power handling of the midrange and woofers will need to match. This will require the sensitivity of the speaker in a room (not the driver sensitivity) and the baffle width plus midrange crossover frequency and slope to determine how the woofer and midrange sum with respect to baffle step correction.

Your current choice of midrange will not have the sensitivity, power handling or SPL output to match a pair of woofers with substantially more SPL than you current pair of Daytons.

Why does the midrange and woofer sensitivity need to match? The midrange sensitivity just needs to be a little bit higher to avoid having to pad the woofer, right?
Can I simply increase the midrange size? NE180W
I considered MTM to increase the midrange power handling, but this adds complexity and limits the size. NE149W

 

[alexcd]

Forget home audio drivers. Since double rs225 doesn't meet the demands, you should be aiming for something like this:

The-Loudspeaker

Nice! But, it looks mighty expensive too.

 

[EarlK]

DIY mates,

<<<<SNIP>>>>

Let's be engineers about this and be critical when needed.

I am planning to use a miniSHARC processor into 8ch of amplification to run them active

<<<<SNIP>>>>

Great thread but want something that really shakes the room and sounds effortless doing so.
Open Source "Tower XL" thread

I'd say be ready to commit to speakers that are 5cu' to 10cu' in size
- ( or else you're simply suffering the quite typical delusional thinking of ; "size doesn't matter").

Here's some great text ( quotes from Troels Gravesen taken from the previously mentioned link ).

The sound?

Hmm... In terms of dynamics and transparency it beats anything I've made before.

This even from speakers twice the building price. Price to pay is size - and weight, not to forget! I had to call in a couple of bodies to help getting the speakers to our living room.

Size matters and none of these drivers have to work hard to do the SPL. The 18" bass drivers hardly moves delivering thunderous bass.

The midrange is as dynamic and transparent as can be and the compression driver delivers a resolution and lack of distortion that leaves even the best of domes behind. Say no more!

Some of the design features here build on client work and one of them had a visitor claiming the sound being too dynamic! How can a speaker be too dynamic?

One thing we've been very good at over the last 50 years - since the days of JBL/Altec/Klipsch and others - is killing the dynamics of reproduced music, and I guess many people have gotten accustomed to dull and lifeless reproduction or maybe never realise that most of live concert dynamics can be had at home. I fully acknowledge that most people may not want home reproduction as dynamic as live concerts.


The horn and the tweeter only takes a few uF of good caps. The midrange takes a lot of good uF, but there is no way around it if we want to hear it all. From the midrange and up you should feed it from the best of amplification you can afford. This speaker will seriously display any deficiency in amplification and source material. Bad CDs and vinyls will sound just what they are!

The good news is that you don't need a huge amplifier to run the MTT section. My 32 wpc tube amp is more than enough and the bottom driven by the Hypex module with its 500 watts is well taken care of. In my test set-up I ran the bass section from my Hypex UcD amp - with the passive crossover. I can't say one way is better than the other. Don't even think the simple passive crossover for the bass driver kills dynamics. It doesn't!

Getting the speakers into our living room and start digging into my record collection was a quantum leap of revelation. Recordings that had previously been "problematic" and subject for unpleasant comments to the producer, all of a sudden came to life and embarrassingly told the story of how weak a link speakers can be, how much membrane area is really needed to deliver the true dynamic of most recorded music and how much is lost in poor energy transfer. The key elements in all this is the 10" midrange driver and magnificent 18 Sound compression driver and horn with its exceptional dispersion.

You can have a four-seat sofa in front of these speakers and all enjoy the presence and phenomenal transparency in midrange and treble. Good bass can be made in many ways as well as the airiness delivered by the super-tweeter in the upper octave. Not so critical. Getting the 200-10000 Hz range right is what counts.

After a long afternoon session with a visitor we both noticed no listening fatigue after several hours of quite loud playback levels. A good sign of very low distortion. Distortion can measured as content of 2nd, 3rd, etc. harmonics, but I think there's more to distortion than that. How drivers with limited dynamic headroom smears detail and colours sound may on a more subconsciously level be the reason for listening fatigue as we have to spend energy listening for qualities that should be there, but just isn't.

Here we don't have to engage in listening, we can just listen, drink our coffee, eat our cake and enjoy whatever our cartridge is able to pick up from the grooves - and by the way, when CDs are really good, they sound good here too.

As said above, I've been seriously disappointed going back in time reviewing stuff I found great many years ago, but that unforgettable memory of the JBL system at Danish Radio some 30 years ago turned out to be valid. I may not have a 2" tape machine, but I believe I have better amps and cartridges compared to back then and I also believe the 18 Sound compression driver and horn betters the LE85/H91 from back then.

Sorry for the super long quote but line after line rings so true based on my own experience as a well seasoned live-audio guy.

It's extremely gratifying to read words like this ( from someone of Troels stature ) that so fully support my own experiences.

Thanks to Zvu! for mentioningTroels "The Loudspeaker".

 

[krivium]

Hi,
Earl:k +1 (from a former studio's geek).
Thanks Zvu, i haven't spoted this one on Troels site ( too much (good) loudspeakers design in there).

 

[Zvu]

You're welcome guys.

Nice! But, it looks mighty expensive too.

It's never cheap to fill large space with pleasant, high quality, audio vibes

 

[andy19191]

If you consider the increased X-max, the displacement is around 2x which would be OK by me.

That was not the question asked. A 10" woofer often has pretty much the same motor and therefore stroke as the 8" woofer in the manufacturer's range. The stroke if far more likely to be the same rather than double. The 50% increase in area will give you something like 1.5 dB more SPL. Is this enough?

hehe, I like the sound of 12"s instead of 10"s!

The point was that my example gave a 10 dB increase in maximum SPL with a 130 litre cabinet and 35 Hz extension depending on tuning. If you don't understand what has created this you are not in a position to look for alternative cheaper/smaller drivers. Is 10 dB increase in SPL enough?

Does this get anyone worried about running them up to a reasonable XO point for the midrange?

The crossover frequency follows from a range of factors several of which I suspect you do not currently know about.

Why does the midrange and woofer sensitivity need to match? The midrange sensitivity just needs to be a little bit higher to avoid having to pad the woofer, right?

If by woofer sensitivity you mean the woofers in the speaker and in the room so that baffle step correction and boundary reinforcement is accounted for then yes. For my example the woofer will be around 95(ish) dB (I haven't done the full sums). What is the sensitivity or your chosen midrange accounting for whatever baffle step loss may be relevant?

Can I simply increase the midrange size?

You need to increase the size, sensitivity, power handling and possibly number if it is to match the efficiency and SPL output of the woofers.

 

[alexcd]

Andy - I think you can take the linear X-max listed by the manufacturer into account which gives the a pair of 10s with twice the linear range as a pair of 8s a much more than 1.5dB SPL advantage. The voice coil length and suspension designs are vastly different for the RS225 and all woofers I have listed. The benefit of using a larger cone would be to further increase any volume displacement or bring in the x travel requirements which can also increase efficiency but this brings other issues that you mention. I will be very happy with 2x 10” in a ported enclosure. My question would be to tune this lower than you gave in your example as I do not have a great feeling on converting to in room response. Is this something you would adjust by trimming the port later?

You make a great point about the midrange and tweeter being able to keep up with so much bass firepower. I’ll keep looking here. I would like to stick with a single midrange but selection would be limited. Two midrange may be the best after all. Is splitting 6” mids in MTM recommended? The low pass would need to be extra low to avoid a narrow lobe. Then of course it’s necessary to see if the 29mm tweeter can handle the extra duty.

High efficiency wasn’t the goal, just higher output. I have plenty of amplifiers to split the load. Power is not the issue.

I appreciate the criticism. Keep it coming!

 

[alexcd]

You're welcome guys.



It's never cheap to fill large space with pleasant, high quality, audio vibes

I appreciate a good speaker but need to keep my audio vibe budget under control. Think of this as a challenge then it can be fun!

 

[andy19191]

Andy - I think you can take the linear X-max listed by the manufacturer into account which gives the a pair of 10s with twice the linear range as a pair of 8s a much more than 1.5dB SPL advantage.

I am not sure why you are struggling to understand. The 1.5 dB increase follows from the 50% increase in area. The quoted xmax of your 8" RS225-8 is 7 mm. The quoted xmax of the 10" RS270-8 is 6.6 mm. So for this manufacturer the xmax has actually reduced rather than doubled but it is still roughly the same which is to be expected.

I will be very happy with 2x 10” in a ported enclosure.

What SPL increase do you expect? And is it enough?

My question would be to tune this lower than you gave in your example as I do not have a great feeling on converting to in room response. Is this something you would adjust by trimming the port later?

I was referring to tuning by changing the port length but this was more for rolling off earlier with a less steep slope which often better matches what the room does to the response. Not sure I can see a point of a lower (non-room) extension but if you want one you would get more by increasing the size of the box but it won't be much. Otherwise a less sensitive driver but that will likely push the power requirements above 1 kW if you want an SPL increase of 10 dB or so. You still haven't told us how large an SPL increase you are looking for?

 

[Zvu]

@Alexcd:

Have you considered buying 4 more RS225-8 and make 4 woofers per cabinet (2 in series, 2 in parallel) ? You get 6dB more than you have now before bottoming them out. Is that increase in sensitivity enough for your needs ?



4 voice coils sharing the load so distortion would be lower. You could do something like Dynaudio Evidence or buy some coaxial and make something like Kef Reference 5/Blade 2. JShadzi used FaitalPRO 6HX150. Saving some bucks on the woofer department gives you the chance to use this coax.

Seems resonable to me and you don't get into trouble with mid and tweeter sensitivity, lobing etc.

 

[alexcd]

The quoted xmax of your 8" RS225-8 is 7 mm. The quoted xmax of the 10" RS270-8 is 6.6 mm.

No, I get it and I see the confusion now. I was not considering the RS270-8. SB29NRX75-6 has an x-max of 11mm and WO24P-8 has an x-max of 17mm though smaller Sd. I expect 129% or 190% increase in raw bass output respectively which is OK.

Thanks for confirming my understanding of the port tuning as well.

 

[alexcd]

Have you considered buying 4 more RS225-8 and make 4 woofers per cabinet (2 in series, 2 in parallel) ?

Yes, I did consider this, but my SPL target keeps going up.

The pro drivers are interesting. The one used by JShadzi is discontinued.

The higher sensitivity is nice, but I am worried about the limited x-max given the woofer output they need to keep up with.

 

[alexcd]

I was curious the sensitivity loss due to baffle step used by designers as a rule of thumb so I looked this up and 3dB seems to be the consensus. Of course there is no replacement for measuring the final design but this was helpful to understand the requirements.

Midrange Sensitivity Versus Woofer in 3-Way?; New Member 1st Post

So, if I plan to use two woofers with 88dB sensitivity, the target would be a midrange with sensitivity of 91dB. Higher is OK but would require a pad. I noticed some designs use less (almost no difference) and people still consider them to be high quality with a few dB extra in the deep midrange and bass.

Here are my calculations:
88dB per woofer + 6dB for 2nd woofer in parallel = 94dB
Midrange target = 94dB - 3dB = 91dB
1st choice: SB Acoustics SB15NRXC30-4 91dB
2nd choice: Tymphany NE123W-08 86.2dB + parallel (MTM) +6dB = 92.2dB

Any others come to mind that aren't too ragged or hard to control peaks?

 

[LineSource]

SB26STCN-4 tweeter
MR16P-4 midwoofer (Sd = 118 cm2 = small'ish)
parallel SB23NRX35-6 woofers

TMWW 3-way Simulations look good for ~91.5 db midrange SPL, with Zmin ~ 4 ohms from the parallel woofers producing modest baffle step gain of ~93db. -- many HT and apartments will put these speakers against the rear wall. -- 1.5-2db baffle step would be acceptable with some help from floor gain from the bottom woofer.

 

[chris661]

For a mid-life crisis build, here's my approach:

- Get a decent 15" PA subwoofer driver. Think Beyma 15P1200Nd.
- Cross as low as possible to a large-format compression driver on a large horn. The BMS coaxial drivers would be a favourite here. You might be able to find a pair of EV DH1a drivers cheaply - they're an older model, but definitely a force to be reckoned with.

Make the cabinet fairly big, tune low, and brace it well.

Hit the 15" with around a kilowatt, and the HF with a couple of hundred watts.

It's a 2-way design, so you can focus on buying a couple of good drivers instead of a pile of okay ones. In-room sensitivity will come out in the mid-90s, so you'll be able to pass 120dB (per side, at 1m) without clipping the amps or stressing the drivers.

None of the home HiFi stuff mentioned so far will come close to that system for sheer effortless output.

Chris

 

[andy19191]

No, I get it and I see the confusion now. I was not considering the RS270-8. SB29NRX75-6 has an x-max of 11mm and WO24P-8 has an x-max of 17mm though smaller Sd. I expect 129% or 190% increase in raw bass output respectively which is OK.

It is power handling that limits output over most of a woofer's passband with displacement only becoming relevant at the lowest frequencies. Compared to the RS225-8 the SB WO24P-8 has a similar xmax of 8.5 mm, slightly bigger area and similar power handling and so will be only about 1-2 dB louder. The SB 29NRX75-6 has better power handling and will be about 4-5 dB louder but it has a DC resistance of 4.2 ohms and so in parallel it will likely draw too much current for many amplifiers. The L version of the 12" SB woofer will be about 9-10 dB louder with a more typical "4 ohm" load, a reasonable box size and 35(ish) anechoic extension.

Concerning midranges. If the woofers in the cabinet and room need 500W+ to reach maximum SPL how much will a similar sensitivity, similar impedance midrange need in order to keep up?