Getting good Efficiency and smooth response, to 3-4-5-way, or not - diyAudio
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Old 1st July 2008, 08:48 PM   #1
pjpoes is offline pjpoes  United States
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Default Getting good Efficiency and smooth response, to 3-4-5-way, or not

I've been thinking about what to do for my stereo. It really is a combination home theater and stereo, i.e. it does double duty. To me, this means its requirements are that it must offer good dynamic range, high peak output levels, while also offering things like a good stereo image, low distortion, smooth response, etc. Now while I know that one way to achieve the former mentioned requirements is with high efficiency drivers, as is done with many high end home theater speakers, my preference is going to be with more typical audiophile drivers. I much prefer the sound of drivers like those from Focal and Scan-speak, to drivers from JBL, Eminence, or B&C.

I recently completed a Focal driver based 2-way using a 6" midbass and a tweeter in a small tower. The design required so much baffle step that it became very inefficient, and IMO, lacked the dynamics and peak output levels I was hoping for. Option 2 became adding a second woofer for a 2.5 way design, which improved efficiency, offered much improved dynamics, and greater peak output.

Ok, but in the end, I wanted more. I've heard speakers from Revel, Focal, and Wilson Audio, which were all either complex 3-way or 4-way designs, and all offered great sound IMO. This leads me to want to try my hand at a more complex setup. I started playing around with the idea of a 2.5 way that used two sets of paralleled drivers in order to give improved efficiency, greater maximum output, and proper balance.

Then I started thinking, do I really think my own crossover designs will work best, I don't know that much. One design I looked at was from Troels Gravenson, known as the Ekta Grande. The enclosure he specs is very complicated (Though very cool), and the overall design is that of a 3-way, using a lot of very expensive parts. While I can handle most of this design, I felt there was no way I could build these enclosures. I also was thinking that, if I'm going to spend this much money on parts, maybe I should consider having someone else build the enclosures. I began asking around, showing the design, and the response I got from companies like Taylor Audio (Lee Taylor), GR Research (Danny), and Meniscus Audio was that A) They could not build this enclosure for less than 2500-3000 dollars, or could not build it at all, and B) that this was a over priced, overly complex design which was poorly engineered, and that they could recommend better sounding and less expensive kits. Are they just trying to make an extra buck and sell me something of theres, or are they right? Is this just a design preference? One view is that his crossover points are poorly chosen, being way too high for a 3-way. My impression from Troels is that he chose those because he felt that the drivers used sounded best with those crossover points, that they were not arbitrarily chosen.

Another option I have considered is the Zaph designed ZRT in a 2.5 way. However, I have talked with various people about this type of design (Not Zaphs particularly), and there seems to be a common opinion that the 18W midbass doesn't have the most natural sounding midrange. I see that Zaph has a very low crossover of something like 1.8 khz. I'm sure this helps, but I again, I hate to spend the money on the drivers, only to find I"m not happy with the midrange.

If people could give me there thoughts, I would greatly appreciate it.
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Old 1st July 2008, 09:11 PM   #2
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I think in your position, I would consider getting a woofer, a plate amp, a good efficient full range and a nice ribbon tweeter. Your box can be divided into two chambers with the woofer and amp on the back. The front will have the FR and a fairly straight forward 12dB high XO point on the ribbon. The FR need not have any XO. There you go, a bi-amped three way that's easy to deal with.

You have wonderful control of your low end, no real XO worries and a nice efficient speaker. I have done similar things twice before.

EDIT: If you're adventurous, you can consider going OB on the FR. planet10 taught me that one.
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Old 1st July 2008, 09:59 PM   #3
pjpoes is offline pjpoes  United States
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Thanks Cal, I appreciate your input, but will be interested in some other idea's following different design mantras. While no accounting for taste, I have tried to like full range drivers, and designs following your basic idea, and find myself reverting back to the more typical. The only full range driver I have ever liked was the Jordan, and it didn't have enough output, nor would it in this type of design. It's also too expensive, IMO. I find Fostex, Lowther, etc to be far too colored, and I'm never able to get past that aspect of their sound.
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Old 1st July 2008, 10:23 PM   #4
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I'm someone who built the full scanspeak 3 way then moved on to 'pro' gear.

The low efficiency of the mids will be a problem unless you go for a large one, which ruins your tweeter choice (lowers xo point).

My 5.5" scanspeak mid used to clip on the opening song of 'kill Bill' (bang bang) at home theatre reference levels. No it wasn't the amp either.... and it was high passed at 250Hz too..

I used 2 x scanspeak 8565-01's per side for bass and they were brilliant. Could be run down to 40Hz for dvd no probs. Any lower they did not have enough output. Most home theater setups cross at 80Hz so that is not an issue. They will shame most subs for quality in the 40 - 120Hz region, they are that good.

If I was going your route I'd build an mtm top with maybe 5" mids. This would be crossed to 2 x 10" drivers running 80Hz - 300Hz.

Active xo's would be a no brainer for this type of setup. Personally I use the behringer dcx but there are better ones available.

Good luck with your project.
Rob.
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Old 1st July 2008, 10:54 PM   #5
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You talk like you want efficiency at first then you mention speak of inefficient power sucking drivers. I don't get it.
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Old 1st July 2008, 10:55 PM   #6
Nanook is offline Nanook  Canada
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Default no don't!

er , OK do!

or wait until I post my "Spirit of Orion" Linkwitz Orion inspired speakers in a future issue of affordable$$audio.

As Cal suggested, Powered sub pair, OB top (or substitute in a boxed design if ya so choose). Relatively inexpensive, low 20 Hz response in room, Fugly. er...maybe not Fugly---I like the looks.

The most expensive part(s) are the subs and the plate amps---about $400 with built in low level crossover. You may be able to get cheaper, but I'm unsure if you'd get better.

I had the idea to provide my wife with some bass, 'cause she's the resident bass-head in our house. I thought a simial sub set up with my castles on top would be really nice. Even a set of Fonkens would be excellent (and please do not discount FR drivers until you've heard these!)

This particular pair will be used in a HT/music FR system at my audio partner's place (the eldest kid's BF). All we have to do is add the top baffles and do a minimal amount of finishing ... Pretty sure even Cal will feel it at his place... , although Dave's place is pretty safe, unless of couse a monsterous Tsunami is caused....


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Old 2nd July 2008, 06:41 PM   #7
pjpoes is offline pjpoes  United States
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Maybe I should clarify better my definition of efficient here. I'm just looking for above average, say 90dbs at 1 watt plus, not 100+. My experience has been that efficient speakers have a poor frequency response, and often high distortion. Speakers with a good response and low distortion however are usually inefficient, meaning you have to parallel drivers to increase efficiency. I prefer that route as I still can get a better response and more natural sound than I can with a highly efficient driver.

I love the sound of a good simple two way system, but, to design them right, you end up with pretty poor efficiency, like in the very low 80's, which is just unacceptable.

A Line Array would work, in just about every way, but, they are expensive and huge. I've thought about doing a small quasi-array using 6 midbass drivers and a single efficient tweeter, but the highs wouldn't be projected in a line array manner, so other than efficiency, I'm not sure I would gain much, plus I would have to be careful in balancing this, as the bass would project with less loss (2pi space) than the highs.

I've been talking with a few people, and one common thread in these discussions is the idea of a separate powered woofer for bass, and I'm looking at GR's newer servo subs with the Servo amp for bass, and then a pair of the 6" Focal Midbass drivers I like, and the tweeters I already have.

As for the electronic crossovers and seperate amp requirements, well it would help with some issues, but for now at least, it's not going to happen. I would need 8 amp channels and either a pair of 4-way crossovers, or...one of the many digital speaker controllers, of which none I am a fan. I do not find the redundant ADC-DAC conversions transparent, and...all of the affordable ones are very noisy in my system. I have the Behringer, I tried it on and off, and just couldn't get past the noise. I mean, keep in mind, I'm a Vinyl guy, with a fairly expensive Turntable, so you can imagine, right or wrong, I don't like any digital conversions in the signal path that can be avoided. A more likely option will be some DIY electronic crossovers with fixed equing based on the passive crossovers. To start, maybe an electronic crossover between these powered bass drivers and the upper range, with a highpass on the upper range centered around 100-150hz or so.
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Old 2nd July 2008, 06:45 PM   #8
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I have never heard one of Troels designs but it appears they are well thought out and designed with the caveat that they aren't going to be easy or cheap to build.

The cabinet in the Ekta grand is complicated. The tilt in the cabinet coupled with the sculpted front baffle translate into lots of extra work. and if you want someone to do it for you, that translates infto "expensive". Without the tilt and maybe the sculpted baffle, the current XO won't work properly.

I have used the SS Revelator 18w mid woofers and think they are among the best sounding drivers I have ever heard. They do have a different sound than say the Seas Excel magnesium drivers but I think they are extremely natural sounding. Now they are high priced for what you get, but certainly are better values than the SS ring radiator tweeter in the Ekta.

If you are looking for an amazing sounding speaker which will be a lot easier to construct, not to mention cheaper all around, I would consider Jim Holtz Statements or Mini Statements.

http://www.geocities.com/cc00541/

These are among the best sounding speakers I have ever heard (commercial or DIY). The midrange with the open baffle mid is fantastic.

Regards,

Dennis
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Old 2nd July 2008, 08:03 PM   #9
tf1216 is offline tf1216  United States
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If you want to build your own speaker I like what djarchow has suggested or go with one of the projects from Zaphaudio or from one of the other DIY guys on the web.

If you want something less complicated but you still want to get your feet wet in the DIY realm, buy a 2-way and some nice subs. Spend your time integrating the two by testing and building subwoofers or working on the active crossover.
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Old 2nd July 2008, 09:17 PM   #10
tinitus is offline tinitus  Europe
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No mention of Earl Gedlees ESP kits ?

Or you may do a 3way with AE TD15S / B&C 6NDL38 / tweeter?, sensitivity just above 90db
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