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Old 6th October 2014, 12:22 AM   #1
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Default 3-way design ideas wanted!

I am planning a new diy project and I would like to know your thoughts!

On a previous 2-way I have come to like working with active crossovers, and after finishing the speakers at hand I plan to move on with a 6-channel diy power-amp. :-)

I will use these speakers in an open-area living room with hardwood floors and a roll-out-for-listening rug. Not the best of conditions, but that is my reality. I listen to all kinds on music, but when I have an evening sit-down with my gear I tend to dig out acoustic music most of the time.

My design goals: I want a speaker that wants me to sit and listen to music for hours, hours and hours. I want good imaging and musicality. Coloration of the sound is not a goal, but a perception of "warm" sound is not necessarily bad.

Also, I do not want to implement a finished kit, simply because that takes away all of the fun for me. I want it to be my own design, at least to some extent. :-)

These are my thoughts on design:
- Three way floorstander for full soundstage
- Narrow baffle design for WAF
- Transmission line for bass driver
- Separate sealed enclosures for midrange and tweeter
- Tilted baffle for time alignment
- Chamfered baffle for low diffraction
- Active LR4 three-way cross-over based on Rod Elliots P09 (Linkwitz-Riley Electronic Crossover)

These are my thoughts on driver selection:
- The level of each driver will be fine tuned using the active cross-over, so neither sensitivity nor impedance is crucial.
- Since I will be using steep filters, drivers need to be a close match in terms of "sound character".
- I do not want to bother with notch filters, so drivers with flat SPL is important
- 4" midrange for good dispersion.
- 1" ring radiator tweeter for exended frequency response and low distortion
- 7" long-excusion woofer

My budget with this is not unlimited, so highly exotic drivers like the C-Quence and stuff like that will not be possible. I think Scan-speak Illuminators are just about as far as I am prepared to go budget-wise. Spending top-dollars for exotic drivers is no self-purpose. :-)

I am currently struggling with driver selection. It is hard to know which combinations will sound natural. I think especially the midrange and tweeter combination is important for the integration and sonic character of the system, especially as I do not want to be messing around too much with the crossovers.

Tweeter ideas:
- SB Acoustics SB29RD
- SB Acoustics TW29R
- Scan-Speak 6600

Midrange ideas:
- SB Avoustics SB12NRXF25-8
- Scan-speak 12MU/4731T00
- Scan-speak 12W/8524G00

Woofer ideas:
No ideas here, I really do not know which TS parameters to look for when setting up a TL box. Any help is appreciated!

Your help is appreciated!
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Old 6th October 2014, 01:29 AM   #2
sreten is offline sreten  United Kingdom
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Location: Brighton UK
Hi,

"All the fun" is actually all the hard work required, and if you
don't wan't to be suggested stuff where all the hard work
has been done for you, feel free to have "fun", but I
suspect your pretty clueless, so feel free to have "fun".

You don't want to be helped, you want to self indulge.
FWIW your list is pretty clueless regarding any reality.

People suggest good designs because they simply are,
to people who have no hope of ever getting there.

rgds, sreten.

http://audio.claub.net/Simple%20Loud...ign%20ver2.pdf
http://www.rjbaudio.com/Audiofiles/FRDtools.html
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 6th October 2014 at 01:37 AM.
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Old 6th October 2014, 01:34 AM   #3
adason is offline adason  United States
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come on sreten, he said 'your help is appreciated!'
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Old 6th October 2014, 01:44 AM   #4
Einric is offline Einric  United States
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Curt Campbell and Jim Holtz used the Peerless NE149 in the Finalist 3-Way for midrange duty.
Here is a brief quote from Speakerdesignworks.com;
" We chose the NE149 based on feedback from others that have compared it favorably to its high end siblings from Scan-Speak. The NE149 was an unknown quantity, so I even went so far as to size
the mid cut out to accommodate SB Acoustics, Scan Revelator and Seas Excel 5 ” drivers in case we were not satisfied with the NE149 performance. The NE149 exceeded my expectations. It tested great and sounded better."

I seriously considered building the Finalists until I got a hold of a pair of beautiful 10" 3-Way Technics.

The RS225 may be worth a look also for your design in woofer duty, or a pair of them for a "slim"ish floorstanding vented enclosure.
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Old 6th October 2014, 02:14 AM   #5
sreten is offline sreten  United Kingdom
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Location: Brighton UK
Hi,

I'm helping. If you want to design an advanced speaker
and can't be *rs*d to analyse other designs yourself but
want other people to do it for you, based on explaining
what is wrong with your set of very lazy premises.

It doesn't work like that. For every error you'll get
a clueless poster saying its OK and do it like that.

A thread is about totally the worst way to approach
any sort of sensible design, and usually gets hijacked
by someone knowing a little more the poster, but not
much more, severely agreeing with the poster too much.

However FWIW :

You cannot build a high quality speaker with the P09, period.
If you think you can you know nowhere near enough to do so.

That is the quandary, and you won't get the answers in a thread.

This isn't car audio, and I'm just making that explicit.

If you are not capable of analysing and understanding all
the designs out there, active, passive, or a combination,
then there is very little chance you can do any better.

Expensive drivers also need very good cabinets, an
area where the majority know next to nothing about.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 6th October 2014 at 02:31 AM.
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Old 6th October 2014, 04:14 AM   #6
Jay is offline Jay  Indonesia
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Location: Jakarta
Quote:
Originally Posted by karha096 View Post
Also, I do not want to implement a finished kit, simply because that takes away all of the fun for me. I want it to be my own design, at least to some extent. :-)
If you want to use active crossover, that would be your own design of course.

Quote:
Originally Posted by karha096 View Post
My design goals: I want a speaker that wants me to sit and listen to music for hours, hours and hours. I want good imaging and musicality. Coloration of the sound is not a goal, but a perception of "warm" sound is not necessarily bad.
It's very hard to achieve this with analog crossover. And shallow slopes (2nd order) tend to give better result in that direction. But okay you already know what drivers to have. Paper only please.

Quote:
Originally Posted by karha096 View Post
- Three way floorstander for full soundstage
- Narrow baffle design for WAF
- Transmission line for bass driver
- Separate sealed enclosures for midrange and tweeter
- Tilted baffle for time alignment
- Chamfered baffle for low diffraction
For enjoyment, I would prefer sealed for the woofer. Midrange OTOH is okay (actually better) with TL or even open baffle (see the Statement or Finalist).

Mid and tweeter doesn't have to be separated if the issue is vibration or box resonance from the bass box. Besides, you may want the midrange to be as close as possible with the tweeter. And you may want to "time align" the bass box with mid and tweeter.

Quote:
Originally Posted by karha096 View Post
- Since I will be using steep filters, drivers need to be a close match in terms of "sound character".
- 4" midrange for good dispersion.
- 1" ring radiator tweeter for exended frequency response and low distortion
- 7" long-excusion woofer

I am currently struggling with driver selection. It is hard to know which combinations will sound natural. I think especially the midrange and tweeter combination is important for the integration and sonic character of the system, especially as I do not want to be messing around too much with the crossovers.
Don't worry too much about dispersion, etc. In open space, big diameter midrange will give you the "authority". But I think the paper coned mid used in the Finalist can be added to your list.

Quote:
Originally Posted by karha096 View Post
Woofer ideas:
No ideas here, I really do not know which TS parameters to look for when setting up a TL box. Any help is appreciated!
Yes, with active equalization and unknown drivers SPL at least it is save to have big Xmax for the woofer. TL box for the low frequency driver is very big. You can use bigger diameter woofer instead, with average to low Sd.

Using active crossover will simplify your design effort, tho you cannot expect great result

Or study Linkwitz speakers and copy or learn from that!

Last edited by Jay; 6th October 2014 at 04:17 AM.
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Old 6th October 2014, 09:23 AM   #7
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Quote:
Originally Posted by karha096 View Post
Your help is appreciated!
A single 7" driver is a bit small for a floor standing 3 way without subwoofers. A pair of 8" drivers is likely to do a significantly better job and given the effort that is likely to be involved may be worth considering.

Since you mention budget as a concern then expensive drivers like top of the range Scan-Speaks are unlikely to be a wise choice. SB Acoustic drivers offer substantially higher value for money.

If you are new to speaker design then a flexible active crossover is very likely to be wise: where to crossover, which crossover slope, how much baffle step will be needed in the room, diffraction ripples, bumps in the driver response, etc... With a tunable active crossover you can do this based on measurement and listening. You could build a fixed one after you know what you want but it is unlikely to consist of two pairs of 24 dB/octave filters if you want to do a reasonable job.

Transmission line speakers are bigger and require more effort compared to, say, a vented cabinet. If you want to make a reasonable job of designing, building and sorting out one then it is hard to see an alternative to finding out about how they work and what they require in terms of driver parameters, length, absorption,... If this isn't fun for you then a rethink may be wise.

Words like musicality suggest you may currently have a less than full grasp of what is involved in designing a speaker that performs well. No problem as a starting point but you are opting for an expensive, complex and inflexible initial design. This is likely to be a problem if you expect it to turn out well. Everybody gets alls sorts of things wrong with their first attempt even if they do not realise it at the time. This doesn't mean don't go for a complex and difficult design but plan for it not to turn out that well and how to move forward if/when this comes to pass.
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Old 6th October 2014, 11:05 AM   #8
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Quote:
Originally Posted by andy19191 View Post
Everybody gets alls sorts of things wrong with their first attempt even if they do not realise it at the time. This doesn't mean don't go for a complex and difficult design but plan for it not to turn out that well and how to move forward if/when this comes to pass.
Yep, you have to be the kind of person who doesn't give up easily.

It's very easy to be deluded and to think that you've created something amazing. A good reference speaker helps and also to try your speakers in someone else system. Trying to find someone who will give you an honest opinion is one of the hardest parts I find. Most people don't want to be rude.
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Old 6th October 2014, 11:52 AM   #9
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Hi - I was fairly clueless compared to the majority on this forum, but managed to build my own 3 way active speakers, which I am incredibly happy with.

They use some of the drivers you have mentioned and measure/sound very good (see pages 7 and 8 for measurements):

Sealed three way monitor - anyone spot any probs before I start?

I use them with stereo sub-woofers to extend the bass, but they will go happily to 40 hz without. I have had a succession of speakers over the years and moved to high end active studio monitors some years back. These have replaced my previous Focal monitors.

Regardless of views, it is possible to use standard electrical LR4 crossovers to implement excellent acoustic results, but - you have to very well behaved drivers with a good 1-2 octaves of relatively flat overlap to be successful.

I have just completed construction of a crossover network, designed around OPA2134 op amps at 240hz and 2100 hz with even better measured results than the results shown in my thread - the crossover is very similar to Rod Elliott's design you have proposed - standard LR4 electrical slopes. I have no eq, but have just chosen my crossover points to coincide with baffle step and diffraction along with the measured driver parameters in their enclosures, and adjust for driver sensitivity and baffle step losses with my power amplifiers. Doing it this way has enabled reasonably flat frequency response, good even power response, and minimal electronics in the crossover network - minimising distortion and noise.

If you are going to do this though I would suggest at the very minimum a UMIK-1 or similar and some measurement software to ensure you get the crossover right - this is what is fundamental to a good design.
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Old 6th October 2014, 04:59 PM   #10
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Quote:
Originally Posted by sreten View Post

You don't want to be helped, you want to self indulge.
FWIW your list is pretty clueless regarding any reality.

People suggest good designs because they simply are,
to people who have no hope of ever getting there.

...

You cannot build a high quality speaker with the P09, period.
If you think you can you know nowhere near enough to do so.

rgds, sreten.
I have already implemented a nice design based on the P09 with OPA2604, the Scanspeak 8545k midwoofer and the scanspeak 9300 tweeter. It measures pretty well, but it probably doesn't qualify as a hi-end speaker on this forum. It is by no regards a low quality speaker system, that much I know. There are certain benefits of active crossovers, one being that I happen to enjoy working with them. I am not in this to challenge guys like you, sreten. So, there is no need to tell me that I am an ignorant fool. My premises are no lazier than anyone else seeking some input on a project. I am where I am in my learning curve just like everyone else and I try to be as humble as I can about it. I am however not alone in wanting to make something that no-one else has made before, even if it turns out less optimal than a proven Gravesen design or something like that. And even if it is simply a combination of pre-proven ideas. That was kind of the reason I asked here for a starting-point for driver selection. So sreten, please spare me any additional rants on my bottomless ignorance and realize that this is hobby of mine, not the quest of a lifetime.

Anyway, now that I have made sure I will be hated for all eternity on this forum for asking the wrong questions and by critisizing one of the forum veterans, let's move on with my hobby.

Thanks Einric and Jay for the tip on the NE149, I will include that on my list.

andy19191, I also Think that the SB acoustics drivers seem to offer more value for money. Maybe not quite as much "pearls for swine".

I think I will take your advice and steer clear from TL designs. Partly because they seem hard to get "just right" and hard to fine-tune, and partly because it would require a bigger box.

Bushmeister, I like your project and I will use your thread for input!

I'm going to do some reading and will be back!
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