Good starter design

jmar

Member
2004-01-07 1:39 pm
Indiana
I had NO IDEA there was a forum dedicated to full range speaker systems!

I have, for a long time, wanted to experiment more with full range speakers because some years ago I built a couple of near field monitors (just something I threw together in a sealed cube) and they absolutely blew me away every time I heard them.

I think the drivers were a 4" Pioneer that I got from MCM.

Anyway, could you good folks lead me to a nice little tower project that will renew my interest and get me "hooked" ?

I only ask because it's so fatiguing sorting through all of the posts.

Something using a currently available driver that is a popular design?

I guess line arrays may be less popular? -- I see a lot of single driver designs.

With the subwoofer I built a few years back I'm anxious to put something together.

Something to be said for these little "no crossover - in phase" speakers.
 
You're fortunate that there are many good designs! The problem is to figure out what will work well for you. I built a pair of Metronomes w/ Fostex FE108e Sigma drivers last summer. You can check out my results under the thread "My Metronome Experience" right here. The Mets have a very high WAF (if that is significant for you.) Bass extension is good; imaging & sound stage are excellent. They produce plenty of volume for my room, which is 13.5' x 17'.

I am currently build a pair of Half Changs w/ Fostex FE206e drivers for my daughter and son-in-law. Mids and highs may not be quite as sweet, but they have more bass extension and can fill a larger room w/ lots of quality sound.

Note that both need baffle step correction (BSC) to reach their full potential. Another expense, but worth every penny IMO. (Some folks don't like BSC, but I swear by it.)

Cheers, Jim
 
The BiB, for sure. I'm about done with a pair for a friend of mine, though mine are a bit shorter than optimal and the mouth is at the floor in the rear instead of upfiring like it should be. gychang built a pair for these drivers initially, using the dimensions suggested by Scottmoose. Insane bass from these little drivers, very pleasant character, and though the cabs are big, their footprint is smaller than alot of floorstanders I've seen.

Kensai
 
http://www.diyaudio.com/forums/showthread.php?s=&threadid=89831&highlight=

That's the thread where gychang presented them to us. I don't think those dimensions are considered optimal anymore, though its obvious that the little Pioneer can handle the tuning length of 120". There's an Excel sheet floating around somewhere that you can use to calc a BiB enclosure. Problem is, there are the published specs of Qts .352 and Vas 8.78 l, and then there are some very recent DIYer measured specs of Qts .578 and Vas of 3.43 l, so things are widely variable there. The ones I've made are only about 102" long, the enclosure volume lays between the calculations for the two different sets of specs, and the mouth is probably a touch too large for even the larger of the two, but I'm getting solid to 50Hz, a clear and audible 20Hz test tone, and a huge, spacious presentation, all from a pair of 4.5" drivers that cost me $20 total.

Kensai
 
For ease of construction I'd suggest the FE127e in the recommended GM designed MLTL.

The pair of FE127E I got years ago is a 4" not too cheap driver that
(after experimenting with some Tangband 3") is the minimum for good sound at moderate volumes. But at $40 each the FE127 is not too expensive either. I've done various builds since just using the same pair and testing the results since purchase..

Godzilla uses this design with a slot port in the front. I used the bottom firing design similar to one made for a driver much more expensive. The build was made from particle board shelving trimmed to size. A few tools like a hole cutter are necessary. A router and a few bits are needed for chamfering and rabbetting to recess and flush
a driver mount.
 
some ideas....

Metronomes and Milevas.

I heard FE127 Mets this past summer and they are excellent and pretty east to built. Very "cute", and therefore high "SOAF".

Milevas are similar but more traditional in construction. again very high "SOAF"

Both worked well enough outside if memory serves me correctly.

The Fonkens (but need two per side for tower use) are a little more complicated to build, but with excellent results as well in my 12'X19' living room driven by a T-amp.

I guess I'm "pro" planet10...sorry for the bias.

and then.. there are other types: MLTL, TQWP, bass reflex, horns etc. Zaph, Zillaspeak, Scottmoose, GM , and of course MJ King (MJK here), Tony Glee, etc all have great designs. You'd have to do an Internet search for all their pages, but worth the exploration.Or look up the DIY list
here

hope it helps,

stew
 
Great -- thanks very much. I'll look at all of those this weekend.

The room is pretty small and I'd like to get in the habit of listening at lower volumes (if I can kick my habit of a bottle of wine along with my music). (Unlikely)

Perhaps a nice low power class A amp to go with the speakers as well?

I was wondering also about some other unconventional designs using multiple drivers?

Anything ever done along the lines of direct/reflecting enclosures like the (gag) Bose 901 etc. They suck, of course, but one driver facing and maybe 2 rear would be a nice experiment?

And for my education -- what are the problems with multiple full range drivers on the front baffle? Problems with dispersion characteristics or something isn't it?
 
Yes, you get interference patterns between the drivers.

A good rule for designs to aim for is that at any frequency, the size of the radiating system should not be more than a wavelength across.

Now at 1kHz, the wavelength is about a foot. So even for small drivers, you get some beaming as the frequency goes up. But if you use more than one driver, you get interference patterns from surprisingly low frequencies.
 
I think the OP is saying that he's already got some Pio A11 units and that's what he wants a design for.

Finished the second A11 BiB last night and had them both running in my office rig. The desk is in a corner, a bit out from the walls and is mostly open work. Had the BiBs about 8" from the wall and toed in a bit, so the air space between the mouths and the walls were triangular with the big end venting out into the corner. Now, when running test tones on them like that, they're only flat to about 50Hz (down 10dB in the low 40s, then bottoming out like 20-24dB down in the 25-30 area, but strangely enough back up a touch to around -18dB at 20Hz), but playing music (Joe Satriani "Crowd Chant") the things totally overpressured that small corner. My monitor flexed to the pulses of the kick drum, and I could feel the kick in my chest as well.

The A11 is a bit forward for me (I'm more of a B20 fan), even with the BiB trying to balance things top and bottom, but they are clear, don't need a sub in the BiB, and in my medium sized but low ceilinged room could play waaay to loud, cleanly, on 10-15 wpc.

My cabs are 11.25"x7.25"x48", so tall, but not much footprint. A more optimal cab would be about 60" tall, but the footprint would be a bit smaller, not to mention when upfiring as intended, the BiB wants to be put in a corner or up against a wall, so they don't take up much space for such large cabinets.

You're not going to get the bass or volume out of any of the other design suggestions, though I'm sure you can get more refinement (better cone control and support, better baffle interaction, etc.). Take a look around at what everyone is showing you, then take a look at your intended room and placement and see what might fit best and what best fits into your build skills.

Kensai
 
Not plans so much, but an image (done in powerpoint, no less) that shows the internal layout. The original was done at 1:1 scale, but I save it out as a GIF and shrunk it for ease of use.

[IMGDEAD]http://12southstudios.com/a11bib.gif[/IMGDEAD]

This was all planned around stock cuts since cutting is a serious and oft erroneous affair for me. The sides are 4' particle board planks. The ones I had were only 11.25" wide, but that was plenty. The front, back, top, bottom and internals were made from cheap 1x6s (which I bought in stock 4' lengths to minimize the cutting I needed to do). The drivers are centered 34" up (too short for use as my office speakers, but perfect for by buddy's place). The mouth in this drawing is 9.5" tall. The one on the new cabinet is 7.5" which was the result of new T/S specs measured by a DiYer (not me) and the new GM Excel sheet for calcing these things. The bigger mouth is definitely better (more authoritative at the speakers lower useable frequency, though below that it doesn't seem to make any difference).

I laid these things out using the boards and pencil, rather than making sure the drawing was super accurate. Some tips . . . make the main internal board and the bottom slanted board are square, end to end, with each other, and use that shape to lay the rest out. You just want the end of the lower slant to seal against the bottom and the top of the main internal board to stop at a point that is equidistant from the front, back and top.

This config is good for a 4' BiB as even in my room which is a finished basement and so has low ceilings, the ceiling is too far away to effectively couple with such a short cabinet if it were vented upward as BiBs generally are. Usually, when inverted like this, folk just have them vent straight down, so the cabs are stood up on legs of some sort, but to simplify construction and to increase the line length (which determines the tuning frequency) a bit, I did it this way. I also feel that this way things are going to sound slightly more open in my friend's big room (his ceilings are like 14', too, so inverted was 100% necessary, even if I'd build some sort of 6-8 foot monster for him).

My build quality is crap, too, so these things are a bit leaky in a couple of spots, so I'm sure anyone with even a bit of skill/real tools could get somewhat better results than me. Also, if you were to build to the specs that Scottmoose gave to gychang (or similar, possibly a new calc using GM's new spreadsheet and a line length around 120") you should be able to get another quarter to half octave of extension from these little workhorses (and possibly better balance due to there being more bass).

Kensai
 
>>> Godzilla uses this design with a slot port in the front.

The slot is actually on the side. I dont claim this to be an optimal design. I was trying to fit the spaces on either side of the fireplace and wanted high WAF. I also wanted it to be simple to build which is why i chose standard size lumber at Home Depot. Here are all the dims if you want to consider building it.

http://www.zillaspeak.com/fostex127eSSB.asp

>>> The A11 is a bit forward for me (I'm more of a B20 fan)...

Me too.

>>> Anyway, could you good folks lead me to a nice little tower project...

Heres another one to consider thats easy to build. There has been discussion of getting better performance from the B20 driver in ported and bvr cabinets but this one is very easy to build and also uses standard sized lumber so there is less cutting. They sound good too.

http://www.zillaspeak.com/pioneerb20-piezo.asp

Godzilla
 
Sorry about that. I have no idea why that didn't work.

Kensai
 

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