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help me figger out which drivers to use!!

shrinkboy

shrinkboy

Addicted Member
i got these raw cabs from russman, free (thanx russ)-- they are made of 1" MDF, 12.5" high, 7.5" wide, 8" deep, external measurement. they have a 1.5" port, 4.5" deep. the baffle is has speaker hole 4" in diameter, with a .5" routed lip so that the routed cutout is 5".

russ suggests doing a cutout for some tweeters to make a two way speaker. but i think they were built for single driver application. the closest i can come is this fostex fe127e full range driver available at madisound.

what do you peoples think? cut for tweeters and do a two way, or go with the full ranger?

the finished unit would go with a sub for a stereo HT system.
 
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Make it a 2-way. Calculate the internal volume and see where the enclosure is tuned with the port. That should give you an idea of what woofer to use.
If you set up the enclosure correctly you could get a pretty good sound from it.
 
I like the single driver option, myself, as this keeps the design crossover-less. That is, assuming you can find a driver which suits your box. My opinion is based mainly on stuff I've read and such, as I've no real experience with FR drivers. Seems you could always go back and add a tweeter if the upper-end extension of the FR-er doesn't suit you. Just some thoughts... - Mark
 
Take a look at this

http://www.partsexpress.com/projectshowcase/kuzimus77/kuzimus77.html

It uses this woofer

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-820

and this tweeter

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-804

which has a good woofer, tweeter combo for small boxes. And the crossover is already worked out for you. Looks like that woofer will fit very well. You may have to use clips like he did.

xoschem.jpg


Here is a Boxplot graph of this woofer in your box... not bad!

TB4IN.jpg


Response is the bold line on the right. The line on the left is max power vs freq. What this means is don't try to drive it to max power on low pipe organ notes with your 200 w/ch amp.

This setup will make for some great bookshelf speakers.
 
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paul c and the rest o' youse guys- thanx for your responses, a bunch. paul, looking around my stuff, i found these http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=290-370 for some project i've long forgotten about, and they are a perfectd fit for the woofer cutouts, down to the screw holes lining up and everything. and, i just got these guys http://www.d-s-t.com/link/peerless/data/811582.htm off of that auction site. i wonder if that handy dandy computational toolbox you've got there could throw out some data given these drivers i have, or will have, in hand. and the crossover, what about some o' them 2 way PE crossovers already done up? i am seriously diy impaired and this will be a major leap into the unknown for me, even at this dinky level.

and did i say thanx again so far?
 
No, a ready made xover is not going to work for you. Your woofer is 4 ohm, the tweeter is 8 ohm, so this is similar to the xover in my earlier post:

3khzxover.jpg


First, both have SPL in reference to 2.83 v. That is good so we can compare apples to apples. The woofer will produce 86 db, the tweeter 89. The tweeter needs to be cut 3 db.

So, change the 10 ohm resistor (in series with the tweeter) to 2.7 ohms (Parts Express 004-2.7).

Change the 8 ohm resistor in parallel with the tweeter to 18 ohms (Parts Express 004-18). Changing these two resistors will give a 3 db cut and maintain appx 8 ohm as seen by the xover.

3000 hz is a good xover point for this tweeter. For this xover frequency, on the tweeter part of the xover use 4.7 uf (P.E. 027-422) in place of the 4.0 shown, and .6 mH inductor (P.E. 255-040) in place of the .5 mH shown.

For the woofer zobel (the cap and resistor in series across the woofer), the values shown on the schematic were fine for that 8 ohm woofer, but yours if 4 ohms. Don't know the Le of your woofer's voice coil, so we'll punt. Use a 5 ohm resistor (P.E. 004-5.1) and 100 uf cap (027-360).

For the rest of the xover to the woofer, use .3 mh (P.E. 255-218) and use 10 uf (P.E. 027-340).

OBSERVE the polarity of the woofer and tweeter! Note they are "cross connected", that is, the woofer's - terminal is connected to the - speaker input terminal. But the tweeters + terminal is connected to the - speaker input terminal. This is correct for a 12 db/octave crossover.
 
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paul-- you're awesome. thanx a BUNCH!! i even almost understand what you're talking about. with your help, i think i'll be able to make this work. i'll let you know.
 
Just follow that schematic. You might want to purchase one of the blank 2-way circuit ooards from Parts Express, and mount the components on that. But that might be too large to get through the woofer hole.

Instead, buy two of these perf boards:

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=320-470

And build your xover as small as possible. Work it through the woofer hole and glue in with blobs of E6000 craft glue.

Now let's look at that Boxplot response of your woofer.

290370.jpg


Oops, not nearly so good as the other woofer. It has a very high fs (resonant requency at 137 hz) which accounts for that big hump between 100 hz and 200 hz.

I would put these back in the drawer and use something else. And if you are going to use the TANG BAND W4-656SB 4", you need to alter the xover again.
 
hey, paul, you're fantastic and a perfect example of AK magic. i've got your emails, i'll get back to you....
 
Paul C said:
I know, I know... you purists will gripe about my use of electrolytics. BUT I did that on purpose... to help make the xover as small as possible to get it through the small woofer hole.
Click to expand...

Electrolytics are perfect. To make it perform like the purists want, a tiny bypass cap of higher quality will cover it. :)

Another driver option is the FR125S from www.creativesound.ca
 
hey, dnewma. thanx. that looks cool. you've seen the dimensions of my cabinet higher up in the thread. do you know enough about this driver you mention to recommend it for my box?

thanx
 
Shrinkboy purchased the parts in the schematic above. Also the Tang Band woofers from Parts Express, and has a pair of nice DT80H 1" domes. Woofers are a perfect fit and he has the hole cut to install the tweeters.

He sent me the crossover parts which I just assembled. Here is the realization of the schematic below.

attachment.php


The perforated project boards were cut with my bandsaw, removing a 1" wide strip along one long edge of each board. This was to get the board as narrow as reasonable so that the completed crossover will easily go through the woofer hole during installation. This is also why non-polarized electrolytics were used.

Note proper orientation of the inductors to keep crosstalk to a minimum. The inductors are glued to the boards with E6000 glue (not hot-melt glue!) AND strapped to the board with Tywraps. These inductors are not coming off accidently. But if the coils were to be replaced for some reason the Tywraps may be cut and a sharp knife blade used to slice through the glue. In addition, there are additional Tywraps on the vertical inductors to prevent the coils from separating.

The resistors and capacitors are also glued to the board. Nothing can vibrate.

The leads are tagged so Shrinkboy can connect the woofers, tweeters and input terminals correctly. I suggest gluing the boards into the cabinet with blobs of E6000 or Aleene's Platinum Bond 7800.
 

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pix of cabs before cut for tweeter

i'm takin' em to my buddy's house today to cut holes for tweets
 

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Paul, I like the crossovers mounted on the boards, very neat.
Do you have any pics of the bottom of the board?
 
Man, you don't want to see the bottom... let's just say it conforms to the schematic I posted above. :D

Seriously, just point to point on the bottom, no traces.

Too late for pix anyway, alreay mailed back to Shrink.
 
gear-- i'll get some photos for ya, but cant right now. they are beautifully constructed-- the man moves to the front of the AK class of willing assistance and DIY acumen....

thanx paul!
 
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