• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Speaker Box: Driver Selection

graywolf

graywolf

Sonically Challenged
***I have several questions about speaker box design that I would like to hear the collected wisdom (knowledge, experience, opinions) of folks here on. I will post them individually so not to overwhelm anyone. I will use "Speaker Box:" in the subject of all of them so folks can find the threads easily. ***

OK, obviously there is a lot to be considered in selecting drivers. My needs are for a low to moderate listening levels, and while there are some small drivers that go really low, however they seem to do that by having very deep excursion levels. That seems to me to indicate that they need high power levels to achieve that bass response. In which case it looks like the way to go if you want to get that bass response at low volume is to go with a big speaker. Am I on the right track here?
 
Register to hide this ad
I am certainly no expert I don't necesarily think bigger is better. The little CV's I have contain only 1 6" and a 1" tweeter. However the surrounds on the 6" is rubber and the cabinet has dual ports on the back allowing for ample travel of the driver. I would think it would be quite difficult toget that same effect from a foam surround driver especially if you desire the overall volume level to be low to moderate. The surrounds on practically everything I own iare foam except for the CV's and the whole East/West Coast sound thing is very evident. Since I am running some cheaply acquired black, ltweight supposed 100watt units at times, like when I am out in the yard and such most of my speakers have been hooked up to most of these hokey components at one time or another. I have heard everything here driven by a variety of junk that some speakers sounded good on 1 unit and like crap on another. I have some speaker ideas rattling around in the empty recesses of my skull that I have started collecting parts to experiment with. Definitely going to build my own cabs. A sort of hybrid East/West cab using an isolated chamber in the bottom 40% to accommodate 2 6" ers with rubber surrounds and dual ports. I understand that there are certain parameters that are pretty hard and fast but a good part of my focus is going to be on the look of the cabinets themselves. and I want to do some side by side comparisons or pairs 1 in real wood cabinet and the other in the "standard "mdf" with veneer. First toy is going to be a pair of JBL G40's. Cabinets are small enough to be cut from board lumber and before the tweeters cooked on them they sounded pretty damned good for an 11" x6" x6". BTW those are single ported to the back with recommendation of beween 6 and 18" from the wall iirc.
Best advice I can give is take your time have fun at it. :smoke:
 
Excursion, for a given volume level, is inversely proportional to piston area of the woofer cone. That is, the bigger the woofer, the less it has to move... which is why I say if you want real bass you need at least a 12" woofer.

And as another guy here on AK wisely pointed out, you can have any two of these three things in a bass speaker:

(1) small size

(2) high efficiency

(3) low f3

You can have only two, not all three.

Physics is a real, uh, problem. Big drivers and big boxes work smoothly.

"Mo' bigger is mo' better!"

Check out this thread. Jay is driving 15" woofers in a big rear loaded horn enclosure with just a few watts... and I mean FEW, as in 1w - 2w.

http://audiokarma.org/forums/showthread.php?t=76130

continued in this thread

http://audiokarma.org/forums/showthread.php?t=76361&page=1&pp=15

and finished to up and running here

http://audiokarma.org/forums/showthread.php?t=84727&page=1&pp=15

attachment.php


Jay's goal was smooth, realistic bass on string bass in bluegrass music, not just hip-hop type thump-thump, boom-boom.

So you may not want to build something that big (and with those horns that system should be comparable to a Voice of the Theatre system), but you get the drift. You aren't going to get realistic smooth bass from a bookshelf speaker. (And Jay don' need no stinkin' subwoofer!)

Macaltec found a very nice, inexpensive 12" woofer (appx $30) that gives good performance down to 30 hz in a 4 cft cabinet. Parts Express 295-320, the Dayton DC300-8 12" Classic Woofer.

Based on his excellent results with the Dayton 12", he suggested looking at the similar Parts Express 295-325, Dayton DC380-8 15" Classic Woofer. With port tuning at 26.6 hz, a 5.4 cft cabinet gives an f3 (low end rolloff) of 30 hz. For that size cabinet, use a 4" dia x 6" long port.

And you can go up to 7.4 cft and get an f3 of 25 hz. For that, use a port 4" dia x 3.5" long.

Not bad for a $50 woofer!
 
Based on his excellent results with the Dayton 12", he suggested looking at the similar Parts Express 295-325, Dayton DC380-8 15" Classic Woofer. With port tuning at 26.6 hz, a 5.4 cft cabinet gives an f3 (low end rolloff) of 30 hz. For that size cabinet, use a 4" dia x 6" long port.

And you can go up to 7.4 cft and get an f3 of 25 hz. For that, use a port 4" dia x 3.5" long.

Not bad for a $50 woofer!
Click to expand...

Paul, what would be the trade offs on this one? The 295-315, PE's 10" Classic, which claims a fr of 25 Hz, and an vented f3 of 33 Hz.? Just casually reading the specs one would think it would be better than the 12" version. Sure it is only 1/2 as loud, but in my appartment that would be an advantage. Are there any other things I should be noticing.

Also, I notice that there are not a lot of drivers that will go down to 20 Hz in most enclosures. Back in the 60's and 70's several speaker systems makers claimed 20-20K +-3db. Where they lying, or what?

An interesting aside. My current 8 inchers on the stands actually take up the same space as a 38x20x16 inch cabinets would, so big drivers would not be a major problem except for expense. The 10 and 12 inch Parts Express drivers would fit in my budget fairly well; the 15's would be an uncomfortable stretch, especially as they would most likely require mid-range drivers as well. Any comments on that?
 
Do not confuse fs (resonant frequency) with f3, which is a speaker system's rolloff point. They are not the same.

For the speakers I talked about before, the fs was below the speaker system's f3. But it would be possible to build, for example, a horn system like Jay's above, with another woofer. The cutoff on that horn is 40 hz. The woofer's fs is 33 hz, below the horn cutoff. That's good. You can't expect a speaker to perform with low distortion at or below its resonance. If you were to build that same horn box, with its 40 hz cutoff, and then stuff a speaker in it that had a fs of 50 hz, you would be wasting 10 hz of that boxes capability, squandering all that wood you put together for a purpose.

My current 8 inchers on the stands actually take up the same space as a 38x20x16 inch cabinets would, so big drivers would not be a major problem except for expense.

RIGHT! That is a great way of looking at it!

I think you get a lot of bang for the buck from that 4 cft cab and the 12". I have not put the Dayton 10" in Boxplot, but when I look at 10" woofers, I usually end up thinking, "Why not go just a little bigger and go with a 12"?"

(I just entered the specs in Boxplot)

OK, this 10" looks good in a 2.35 cft cabinet tuned to 28 hz (Port 2.5" OD x 5.25" Long). Looks like f3 is about 28 hz. Not bad!

Look at the this thread:

http://audiokarma.org/forums/showthread.php?t=86762&page=1

And use the same tweeter and schematic I suggested for use with the Dayton 12".

Also, I notice that there are not a lot of drivers that will go down to 20 Hz in most enclosures. Back in the 60's and 70's several speaker systems makers claimed 20-20K +-3db. Where they lying, or what?

Most of the ones that made that claim were lying. There were a few, and very few, that could do that. To be honest, there is very little musical information below 30 hz. And for most pop/rock if you have solid response down to 40 hz, that is plenty.

And I can show you speakers that only go down to f3 = 60 hz, but they sound like they have a lot of bass. They do, only it is mid bass. Many people confuse loud midbass with real bass or the thumps generated by "Johnny One Note" subwoofers. For 99% of music, you can run a 30 hz "subsonic filter" and it will protect your speakers and amp with no audible effects.
 
Paul C said:
Do not confuse fs (resonant frequency) with f3, which is a speaker system's rolloff point. They are not the same.
...
And I can show you speakers that only go down to f3 = 60 hz, but they sound like they have a lot of bass. They do, only it is mid bass. Many people confuse loud midbass with real bass or the thumps generated by "Johnny One Note" subwoofers. For 99% of music, you can run a 30 hz "subsonic filter" and it will protect your speakers and amp with no audible effects.
Click to expand...

I have been modeling some stuff and finding it interesting. By about doubling the box size I see you can get a bit of a bass boost at the bottem end, but I suspect that would only be good at low volume levels (OK for my personal use) but maybe would make the speakers boomy if played loudly (???).

Also I just did a bit of research and it seems like the lowest note on a grand piano is about 27 hz, and the double bass is about 41 hz. So for concert stuff you may need that low low response, but for jazz, etc. you maybe can get by with a less expensive system.

As an experiment I moved my little kitchen speakers into the living room and stacked them on top of the 8 inchers. Running as A and B together it soulds a lot better than either one alone. Which brings up a question. What happens if you use a small mid-bass for your mid-range? The reason I ask that is because you can often get one far cheaper than a "designed for" mid-range driver. Also what about designing that box so the mid and tweet is in separate from the woofer, would the advantages offset the complication?

As to copying some one elses design, to my way of thinking it is more fun trying to understand the principles and then doing your own thing. I mean, if cost is your sole object it is cheaper just to buy some used speakers. Right? I personally tend to be a minimalist, wanting to find out what is the least, that will do the most.
 
Guys, I just did a "How To Use Boxplot" thread.

http://audiokarma.org/forums/showthread.php?t=87311

Boxplot is a free download which can either help you to design a box for a woofer you have, or select a woofer for a box you already have. Or see how a woofer you already have will work in that pair of boxes you just picked up cheap.

Also I just did a bit of research and it seems like the lowest note on a grand piano is about 27 hz, and the double bass is about 41 hz. So for concert stuff you may need that low low response, but for jazz, etc. you maybe can get by with a less expensive system.

You are exactly right! This is just what I have been saying.

Also, if you have ever listened to a real bass, or a real piano playing that far left hand key, you know that those notes are not at the same volume as the rest of the instrument.

In fact, I can play old recordings for you of bass saxophone, whose bottom note (a concert Ab) has a fundamental of 52 hz.

I can easily demonstrate with an equalizer, or even playing on my laptop's tiny 1" speakers that you can still hear the bass line. What you hear mostly for those low instruments is the overtones rather than the true fundamental. I can show you graphs of saxophone tone, just for one example, that shows that the fundamental is not as strong as the first and second overtones. Many bass players report the same with certain brands of strings.

Where you really can hear, or rather feel, those low notes are when listening to full orchestra recorded in an actual concert hall. You can hear and feel reverberations and other sounds whose wavelengths are too long for small recording studios.

For most music, 40 hz is a realistic goal, with 35 hz even better. If your speakers truly will go to 30 hz, they are very good.
 
One thing to consider- I've used the Dayton Classic 8", 10" and 12" woofers extensively... the 10" has MUCH BETTER midrange response than the others. The 8" has a big "whoop-de-doop" in the upper mids (a dip at around 1500 Hz, followed by a BIG PEAK at about 2250 Hz, which is kinda hard to deal with in a 2-way, IME), and the 12" also has a peak at rolloff... but the 10" is DA BOMB as far as integrating with a tweeter. The 295-315 Dayton Classic 10" has EXEMPLARY response up to right about 2Khz... where it drops right down and rolls off, no muss, no fuss.

I've seen several good-sounding 10" 2-way systems using that woofer... many of them using the Dayton silk-dome tweeter. HOWEVER- it'd be interesting, to make a "Baby Everest"... use Paul's favorite, the KSN-1142 piezo horn driver, on THIS horn:

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=270-302

... with a Dayton 10" ABOVE and one BELOW the horn. Make one serious MTM!

You MIGHT even be able to get by with just a coil on the woofer, and a resistor/L-pad/cap on the peizo.... I'd bring in the woofer at about 1500 Hz or so with a coil (roughly, a .4 to .5mH inductor, for both woofers wired in parallel), and use whatever size cap on the horn, to blend to the woofer.

As for cabinet... the size mentioned above (38" x 20" x16") gives about 5.5 cubic feet internal volume. I can say, FROM FIRST HAND EXPERIENCE, that a pair of Dayton 10" Classic woofers WILL WORK GREAT in that box. Tune it to about 28 Hz, good bass to well below 30 Hz...

Whattya think, Paul? :D Should be an effective 2.83V sensitivity of about 93-94 dB, from the two woofers in parallel!

Regards,
Gordon.
 
BTW: I've got graphs, measured on LMS, for the Dayton 8" Classic and 10" Classic woofers, that illustrate how much better behaved the 10" is. Here:

http://www.geocities.com/gordonwaters/Speaker_specs.html

Though the 10" has a dip around 900Hz in the measurement, IME, it doesn't show up as an audible problem in practice. The important thing is the LACK of any real bad behaviour (ie, big dips or peaks), ANYWHERE in its response!!

Regards,
Gordon.
 
OK. Now I've gone over the edge, officially, on this idea. :D

Here's a sketch of what I was mentioning above. Dual Dayton Classic 10"s, with a horn between. I took the liberty of changing the proportions a bit because I thought it looked better, and well, because I could. :D Dimensions would be about 44" tall, 14" wide and 18" deep... a bit more "handsome" tall tower shape...
 

Attachments

  • big ass mtm dayton 10s.jpg
    big ass mtm dayton 10s.jpg
    14.6 KB · Views: 45
GordonW said:
OK. Now I've gone over the edge, officially, on this idea. :D

Here's a sketch of what I was mentioning above. Dual Dayton Classic 10"s, with a horn between. I took the liberty of changing the proportions a bit because I thought it looked better, and well, because I could. :D Dimensions would be about 44" tall, 14" wide and 18" deep... a bit more "handsome" tall tower shape...
Click to expand...

Good stuff, Gordon. I have been thinking that a retro looking AR-2 style box would be nice to do with that driver.

The more I play with the 10 incher's numbers the nicer it looks. What a sleeper. Too big for the small speaker guys, too small for the big speaker guys, and just right for real music. I am beginning to see why Henry Kloss liked 10 inchers so much, and this Dayton Classic seems to fit right into a sweet spot, and can work with about any size box, ported or unported.

WTW's are too complicated for my taste, also a too expensive for my budget. However, a simple 2-way with the 295-315 looks very possible.
 
Well, for that simple 2-way, again, that thread mentioned above has your box size and port dimensions, parts, etc. for the Dayton 12", but you can use the Dayton 10" with no change in crossover values.

GordonW, that horn looks great! That should work very well with the KSN1142a or he could use just the KSN1165 with its built on horn. I'd bet the Dayton lens and 1142a would be a bit smoother and have better dispersion.

Graywolf, the KSN1142a is the same driver as in the KSN1165a, but it is a screw on version to mate with most 1 3/8"-20 horn lens, whereas the KSN1165a has a smaller permanently glued on horn lens.

So, referring to this schematic:

attachment.php


You can use it as is. GordonW's suggestion to simplify it would involve leaving the tweeter section alone.

In the woofer section change the 1 mH coil to .7 mH. Delete the 11 uf shunt capacitor. Leave the Zobel (8 ohm resistor and 40 uf cap) as is.

Either tweeter setup would work well.
 
Well Paul, Gordon,

you guys have me thinking. I have been playing around with some possiblities. Big-10, the max size box that 5.5 cu ft monster. Tower-10 the same box reduced to 12 inchs wide (12x38x16 3.3 cu), and the Retro-10 (AR-2 styling at the recomended 2.2 cu ft). All vented, all using one 295-315 woofer and one 275-070 tweeter.

I think that I would prefer that Dayton Silk Dome to the piezo horns you guys recommend, I just do not thing they would work as well in my room situation. Also the Silk Dome matches the Classic 10's SPL so there would be no need for for an L-pad network. The tower looks like it would be the nicest, tuned to 27 hz or so, it would go down to inbetween the others without the humps the big box gets. I kind of am visualizing a rounded edge '40's looking wood cabinet, cool or what?

So I am feeling rather enabled here, which is bad because ordering those drivers will stretch my budget almost to the breaking point. But, darn those guys at PE, they just put the Silk Domes on sale, so now seems like a good time to do that. Also it will not be something that will be going together quick because there is the lumber to get, and then I will need to do a bit of research on the crossover thing. That last is because I have run the numbers through several modeling programs and get different answers from some of them, and I do not know at this point why that is. What I am sure of is coils have gotten expensive all of a sudden. So there surely will not be a working system until next year at the earliest. I am going to sleep on this idea before I make up my mind.
 
The 275-070 tweeter needs to be used somewhat higher, and the woofer will not meet it.

Using the KSN1165 or KSN1142, the 1800 hz crossover point, the woofers breakup peak is covered, reduced, and smoothly meets the tweeter, which carries the load from 1800 hz on up.

The 275-070 is an excellent silk dome tweeter, certainly as good as is used by many audiophile speakers. But it should be crossed higher, about 2500 hz - 3000 hz.

Using it as low as 1800 hz is possible, but you will need to use at least a 2nd order crossover to isolated it from damaging low frequencies. I have never used a 1" dome under 2500 hz.
 
If I were using ANY 1" dome tweeter to 1800 Hz (with the exception of the "air-spring" EPI/Genesis tweeters, which are another kettle of fish entirely!), I'd be inclined to use a third-order (18dB/oct) crossover. Gotta protect the tweeter from resonance! Or, as an alternative, a second-order (12dB/oct.) with a "resonance trap" (LCR circuit in parallel with the tweeter, to damp out the impedence rise at resonance, and ensure the crossover actually WORKS at tweeter resonance properly). Much more complicated, than a higher crossover point!

The great thing about the speaker configuration Paul and I are talking about, is that it would have several advantages:

1) the tweeter would EASILY meet the woofer. Both would be running in "optimal" ranges.

2) the dispersion of the woofers stacked, would be wide in the horizontal dimension, but NARROWER in the vertical... very similar to the pattern of the horn in question! It's big enough, that it won't have "diffraction pattern flip"... and it should be quite good off-axis, at crossover!

3) the speaker should handle NEAR INFINITE POWER without worry of blow-up. Though the Dayton woofers are only rated at 85 watts each, I can say from experience, that 125-150 watts will NOT hurt them, as long as there is NO CLIPPING. So, the speaker could even handle max output of the "big iron" mega receivers (SX1980, Sansui 33000, Kenwood KR9600, etc)!!

Could be quite stunning, if tuned right... :scratch2:
 
That KSN1165a costs about the same as the Dayton silk dome, though there is the added cost of having to order it from Martin Sound rather than PE. On the other hand, the KSN1165a is so simple and easy to use, and has outstanding range and performance, in my mind it is well worth it. And in a living room, home situation it is almost impossible to burn out. It will last many years. Once you hear it you'll change your mind about all that "piezos are harsh" or "sound bad" stuff you hear.

The KSN1165s and 1142a driver are good up to 100w, with a protection circuit that protects from 100 w to 400 w level. In that range there is "soft limiting" that is almost inaudible. You won't burn these out. I can't do it in auditoriums or outdoor festival gigs.

The reason piezos get such a bad rap is they are used in some very blarey, blatty DJ speakers. They are used in those because they are inexpensive and durable. But those speakers have boomy, unnatural bass, but no one complains that woofers with red-orange surrounds sound bad. Certain piezo models, when used in well designed speakers can and do sound very good.
 
Well, life sucks (or maybe it is just Social Security), so I am not going to be ordering anything right now anyway.

I would like to hear some speakers with those piezos playing music like I llisten to it in a small room. It is not so much the piezo part that worries me, it is the horn part. Or more precisely it is the LOUD part. I feel like I keep saying that I live in a small apartment with barely adequate sound proofing. In fact a month ago it was inadequate, but some ongoing renovations on my part are helping that. Of course horns may be quite capable of playing softly, but every set of horns I have ever heard was turned up to deafening.

Very clear, soft music is what I want to hear.

I guess you guys are probably right, but I have no experience to verify it.
 
Gray, it might interest you to know, right now in my living room are speakers that have a 10" Speakerlab 1008b woofer in a 2 cft sealed box with a KSN1165a tweeter, crossed over with almost identical circuit that that I had printed previously, but for the zobel values (tailored for that woofer).

They sound great at all volumes.
 
You must log in or register to reply here.
Back
Top Bottom