[vann_d]

Hi All,

I'm getting really interested in speakers, speaker building, subwoofer building, etc. The question the keeps coming to mind is why would I buy/build a full range speaker or even a speaker that extends below 80 Hz when we all know how much we all love subwoofers here on HT shack. Seems to me that anything below 80 Hz is irrelevant when you incorporate a sub(s).

I've heard the arguments about being able to locate the sub and at what frequency that is possible etc. The simple fact is that subwoofers are cheap (in my limited experience) compared to designing a speaker to achieve true full range. I'd rather build two in stereo. You can buy two cheap subs for around $400 and put your bookshelves on them.

Additionally, I'm curious about the output capabilities of different bookshelf speakers. Should I rely on power handling? If a certain speaker has a 5 1/2 inch woofer and can extend down to 80 Hz will it yield the same impact as a 7 inch driver with the same frequency response at the same power levels? This part is confusing. Seems like the 7" should dominate but frequency response charts are always at low levels.

I like my music at high levels. I want maximum impact. But that doesn't mean that I want fullrange speakers if I'm gonna have a subwoofer anyway.

Advice?? Wisdom??
Thank you

-Vann_d

 

[dyohn]

A few thoughts. First, building a full-range system that you then cross over at 80Hz with a subwoofer is not a waste of driver capability. Just because you set a crossover at 80Hz does not mean the main speakers will not be asked to reproduce lower frequencies. A crossover is not a cut off, it is a slope. If it's say, 12db/octave that means the mains will receive 40Hz information, but it will be at -12db compared to the signal level at 80Hz. So those woofers still need to be able to handle lower frequencies. Pushing a driver below it's design bandwidth results in increased distortion, which is bad.

Next, if you are after the highest dbSPL at a given frequency/power level, several things will determine the output level. One is the sensitivity of the driver (and the overall efficiency of the system) and second is the moving piston area of the driver. All else being equal, a larger cone will generate higher sound pressure levels in the room. If you want the best bass output and you have the choice between a 5.25" woofer and a 7" woofer I say go for the 7" woofer every time, as long as you are also using a dedicated midrange driver. If it's a 2-way system then the choice becomes a little trickier; but me, I use a 6.5 or 7 inch-er in every design I build if I can.

Ultimately all loudspeakers are a compromise. You just have to decide which set of compromises creates results you can enjoy. Go for it!

 

[Drew Eckhardt]

Hi All,
Additionally, I'm curious about the output capabilities of different bookshelf speakers. Should I rely on power handling?

No, because at the bottom of their range drivers are limited by excursion and distortion becomes unacceptable before they run into their mechanical limits.

If a certain speaker has a 5 1/2 inch woofer and can extend down to 80 Hz will it yield the same impact as a 7 inch driver with the same frequency response at the same power levels?

A 5.5" driver lacks the displacement needed to play cleanly down to 80Hz for subjectively realistic acoustic music listening levels to say nothing of home theater.

Lets use the Seas Excel W15CY001 as an example. It has 75 cm^2 of surface area (Sd), and is linear out to about 4mm (xmax) which yield only 88dB at 80Hz and 1 meter using less than 2 Watts to get there. Crossed to a sub-woofer that only nets 94dB per channel.

Power handling is spec'd at 70W; although with mechanical limits of 7mm in one direction you'll run them to their stops with under 6W at 80Hz.

Even an 8" driver is marginal.

The Seas Excel W22EX001 has Sd of 220 cm^2 and 5mm xmax which net 99dB at 80Hz. With a sub-woofer you'll get to 105dB at 1 meter which is perhaps 100dB at your listening position.

The other complication here is that driver directivity is a function of the wave lengths relative to diameter; so for a given directivity the 5.5" driver will play .8 octaves higher.

To mate a tweeter to such a driver without having polar/power response problems you're going to have to cross it over lower, with a full octave calling for 4X more excursion to reach the same SPL.

That will call for an extra beefy tweeter.

I like my music at high levels. I want maximum impact. But that doesn't mean that I want fullrange speakers if I'm gonna have a subwoofer anyway.

You need more mid-bass than you can get out of most 2-ways. Since most people want low bass and you've already paid for the driver, cross-over, and cabinet such speakers built for the consumer market will be full-range and sold as such.

Advice?? Wisdom??

With traditional midrange sizes you want at least a 3-way. An 8" 2-way (this is the limit for beefy conventional tweeters) might work especially with stereo sub-woofers (a 120Hz cross-over will get you to 112dB with the above example). A 2-way wave guide design which lets you use a large (even 15") midrange driver without compromising polar and power response will work.

 

[vann_d]

So if I go with an MTM or TMM instead of a TM I'm doubling my Sd (given the same driver size)...correct? Does that mean my SPL capability goes up accordingly? Does this also mean that I get the benefits of the smaller driver when crossing with the tweeter? If so, I could see why these designs are so popular.

Since I'm a beginner, I was hoping not to have to do a 3-way. There are not a lot of kits out there (any?) for 3 way designs. Almost all are 2 or 2.5 way. Not sure way 2.5 way means.

I think I'm starting to understand. Thanks guys!

 

[ironglen]

the 2.5 way design uses the same mid drivers below the other one (or two in an MTM) producing the lower freqs, so it often has more drivers used as they are needed to prevent over excursion, I'm interested in this because it can be slimmer.

 

[Drew Eckhardt]

So if I go with an MTM or TMM instead of a TM I'm doubling my Sd (given the same driver size)...correct? Does that mean my SPL capability goes up accordingly?

Yes, by 6dB.

Does this also mean that I get the benefits of the smaller driver when crossing with the tweeter? If so, I could see why these designs are so popular.

Part way.

Horizontal polar response is similar regardless of whether you have one or two midranges, although with two you get a power response notch due to vertical polar response which is more severe in MTM designs. I think this is why MTM designs don't sound as natural as MT plus woofers.

Since I'm a beginner, I was hoping not to have to do a 3-way. There are not a lot of kits out there (any?) for 3 way designs.

There are well-respected 3-way designs you can build at a variety of price points.

Linkwitz Orion/Pluto+ (linkwitzlab.com, the Pluto+ may not give you the volume you want but it's an example), John Krevosky NaO/NaO mini (musicanddesign.com), Dennis Murphy MBOW1 3-way (murphyblaster.com), John Krutke (zaphaudio.com) ZDT3.5, Statements.

Cost can be more than double a 2-way (there's more magnet and metal in the woofer and the reactive cross-over components are bigger due to the low frequency)

Almost all are 2 or 2.5 way. Not sure way 2.5 way means.

A second low frequency driver which only has a low-pass filter so you can do baffle step compensation without loosing sensitivity and can have 6dB more headroom than with a 2-way using the same mid-range driver.

I'd do a 2.5 way before a 2 way with multiple midrange drivers since it'll have the same excursion limited head-room and have better power response.

 

[Drew Eckhardt]

You want to look at Siegfried Linkwitz's SPL spreadsheet. Use the monopole column, add 6dB for drivers operating into half space (say a floor mounted bass driver or a tweeter), and add 20 log # drivers for multiples.

www.linkwitzlab.com/spl_max1.xls

Reading Vance Dickason's Loudspeaker Design Cookbook will give you a better understanding of the trade-offs involved in speaker design.

 

[evilskillit]

Why build full range towers... Because they're cool? Thats a pretty good reason.

 

[vann_d]

Reading Vance Dickason's Loudspeaker Design Cookbook will give you a better understanding of the trade-offs involved in speaker design.

Thanks for trying to explain but I don't understand everything you said here. I really do need to read this book...

Oh, and thanks for the project references. I hadn't heard of these except for the Zaph one that is on Madisound

 

[vann_d]

Yes, by 6dB.

6dB? That's a lot! I was expecting 3dB but I don't know any of the math behind the calculation. Again, I guess it all points to more reading for me ...

 

[fbov]

As I recall, it's 3dB for the second driver and another 3dB when wired in parallel due to the halving of impendence - at a given voltage, a parallel pair pull twice the current of a single driver.

As to speaker designs, here's the master thread
http://techtalk.parts-express.com/showthread.php?t=211558

There's more to this than you think, so my standard advice is to go with a proven design that others with like reauirements have built and found met their needs.

HAve fun,
Frank

 

[sfdoddsy]

You could also make the argument that two truly full-range mains paired with a sub can smooth room bass modes along the lines of what Earl Geddes and Floyd Toole suggest.

And, as mentioned above, they look cooler too.

 

[Synthsayer]

I am really glad to see this thread.
All of the speakers for my DIY 2-ways use the same 5.5" Vifa mid/woofer. They sound nice but don't really put out the full mid-bass I would like to hear from them.
But, all the speakers seem to work well together for surround effect. Same drivers, same crossovers. (Same problems).
Since I have a very nice pair of 10" woofers I would like to make a psuedo-tower. My main concern is that by using a 3-way system as front L+R combined with 2-way Center, Surround L+R, I will encounter phase problems. The 2-ways use a passive 6db low pass and 12db high pass at 3500Hz.
If I made a 3-way system and used a mid to tweeter crossover point of 3500hz with identical slopes, then add a first order woofer to mid crossover at around 400Hz, would that make sense? I suppose I could pull the crossovers out of the existing cabinets, then put them into the new ones and add the first order crossover at around 400Hz.
Next part of this question:
The 10" woofer can use a 1.2 cu. ft. enclosure and achieve an f3 of about 40Hz. Would this increase in piston area and the woofer's placement closer to the floor possibly fill out the low end and mid-bass which I would like?
I have played drums since I was 7 years old and I know what a drum kit should sound like. I also play keyboards, and some guitar and bass. Even though I am using the NHT1259 sub with a nice sub amp, it still lacks the real full mid-bass and bass quality I would like for both home theater and music reproduction.
Thanks in advance for your responses.

 

[1Michael]

Synth, you might want to start your own thread since your post has nothing to do with the OP

 

[harami]

the 2.5 way design uses the same mid drivers

below the other one (or two in an MTM) producing the lower freqs, so it often has more drivers used as they are needed to prevent over excursion, I'm interested in this because it can be slimmer.

You are absolutely right, More drivers plus over excursion prevention with slimmer model is always a good deal, It should be interesting to test it.

 

[ironglen]

You are absolutely right, More drivers plus over excursion prevention with slimmer model is always a good deal, It should be interesting to test it.

I'm in the process of trying to integrate/use a set of 6 MB quart satellite monitors, QL C 50 SAT, that is stated 68-32khz, perhaps by building bass bins below them using 2 anarchy drivers each to create nice, powerful free-standing mains on the cheap.

Regarding the original post. The think the real benefits of fullrange towers are increased output capability(my in-wall left/right main output is severely limited), strong/accurate 2 ch stereo sound especially for music, visual appeal (for some people), and perhaps greater depth from the front stage. Did I miss anything or get anything wrong?

 

[ironglen]

Looking back at the original post, I believe a good quality MT or MTM coupled with a sub for <80hz material along with suitable amplification will probably satisfy most listeners. There is probably a smaller segment that have greater expectations or a larger/less-lively listening area that will probably seek a bit more ummph:wave: Some may be perfectionists and want to diy better than they can afford/even buy. And then there might be those that are sick, with upgraditis, constantly trying to improve upon their sound, eh?

 

[tonyvdb]

why build/buy fullrange towers? I think this question needs to be looked at from a music standpoint. There is usually not much information below 30Hz Jazz and Classical are the exception so full range towers alone is usually adequate in a small to medium sized room.
Most good receivers and pre pros have a pure direct mode and regardless of if you do or do not have a sub is irrelevant as the direct mode disables the sub output. This requires a person to either use the stereo mode for music or get some/build some good quality full sized towers that will go down to at least the 30Hz range.
It is true that adding a sub to good bookshelves will sound very full and if you have the space and are running the sub through its high level inputs or bypassing the receivers processing it does work well but really bypasses the purest way of thinking a two channel rig should be used.

 

[1Michael]

It all comes down to two main questions in my world.
1. How much cash do you have to spend.
2. How big of a box can you handle?
These will determine whether you will go with a tall tower or small bookshelf and of what quality caliber.
Until these are answered there is no point speculating...:spend::T

 

[vann_d]

It is true that adding a sub to good bookshelves will sound very full and if you have the space and are running the sub through its high level inputs or bypassing the receivers processing it does work well but really bypasses the purest way of thinking a two channel rig should be used.

I just don't see any reason why (musically) it should matter whether the driver reproducing your low frequencies is physically in the same box as your mid/upper frequency drivers. Most full range loudspeakers have a physical separation between driver enclosures anyway. Is there some big component being missed by not having the expensive passive crossover? Also, what exactly is wrong with the receiver's processing?

From my (limited) experience, many of the "pure" ways of thinking in audiophile-land make absolutely no sense from an engineering perspective.