Can you turn a woofer into a full range driver?

[kach22i]

Ignorance is bliss, so I must be in bliss.

I will attempt to turn a 4" and a 8" carbon fiber woofer into a 4" and 8" full range drivers.

Gjee Whizzers.

Almost reaching as high as 10khz, they just have another 10 to go.

I expect what ever I do shall suffer beaming or shouting issues, so I also plan to incorporate some sort of blocker/diffuser into the final design. I imagine a sphere or half-sphere hovering over the cone/whizzer area.

Much to my surprise the CF drivers are very dry and paper-like. There is very little resin on them. So little resin in fact that part of my design may be to add epoxy resin to either the front or back and stiffen it up. Which in turn should raise the frequency response, be it at perhaps a more jagged or peaky level.

If you want to hold your opinion until after I do things, that is fine. I do plan to experiment on a big cardboard box full of spare drivers before touching the CF drivers I actually spent money on and not found on the curb when the college students moved out of town last spring.

Anyway here is the MCM 4" and 8" carbon fiber drivers selling for what I think is a fair price. All I can say about MCM is that one of my $6 back-up tweeters I bought in case I fail at producing a super whizzer came in damaged from shipping. I called them and they are mailing me a new one - just like that.

Pictures: Yes that is a vented pole piece on the 8" driver, just like the big boys have.

8"

4"

Both

Poor little tweeter.................

I'm not sure, but I think that the light coming through the drivers is actual air hole openings in the CF weave, and not just translucent resin. I will take a close look when I have more time. Somehow this just feels wrong, I'm open to hearing your opinions on this as it could be not normal.

I hooked them up and they play, only did low levels for a few short minutes but already have some first impressions "in free air".

1. The 8" driver has a rich deep sound and nice fast bass, but I will be hard pressed into converting this into a full-range unit. Vocals are good, bass has depth, just no zing at the top end "as is".

2. The 4" driver lacks the large uncongested openness of the 8" driver but should be a breeze to convert the upper frequencies. Vocals are there, not as rich as the larger driver though.

3. I also hooked up the tweeters to test them, they are not very efficient compared to the sound levels at the same location on the volume control. It will be interesting trying to match sound levels with the mid-woofers, if I go that route as a last resort.

Link to CF drivers below (the top two), PDF's in link provide frequency response charts.

Search results for "mcm die cast woofer 55-3*"

That is all, except you might want to see the Whizzer Thread where I posted some research images and links.
http://www.diyaudio.com/forums/full-range/180690-whizzer-thread.html

 

[Ron Party]

I really enjoy reading about your endeavors in matters audio. You seem to be having a lot of fun. Kudos to you.

 

[kach22i]

It's as easy as A-B-C as a young Michael Jackson once sang.

Comments:

A: "A" is the strainer screen form the dollar store 2-part plastic epoxied on. Yes, I get more highs but not a huge amount and there is a slight canning affect.

B: "B" is the tall open top cone made of craft store brass which might not be real brass. It is the stuff you press down on to get embossed reliefs. More highs than the screen, plus it seems to clean up the sound of the speaker. The sound out of the cone beams straight out and can be deflected by a sphere, and the off axis sound is much better balanced than I expected.

C: "C" is the driver still hooked up to a choked tweeter (16 ohm Panasonic on the back listing). This was good to do with a tweeter hooked up because I could directly compare the sound out the the crown looking whizzer to the sound coming out the the tweeter. They were similar but the whizzzer actually sounded cleaner and more extended than the tweeter close up. The wavy crown top shape comes out of my hovercraft project where I made the splitter wavy. I succeeded in breaking up sound nodes and made the craft more quieter (half as noisy now). To do this on a whizzer was to knock down any single frequency beaming. The sound is directional, but like the open top cone model really good off axis, better than the original driver in fact. The original driver is rather horn like sounding with it's deep fluted shape. So far this is my favorite configuration, but not my last, not by a long shot. I have not made a "Super Whizzer", only a whizzer. A "Super Whizzer" by my definition is equal to a tweeter and maybe even a super-tweeter's performance.

What's Next?

1. I have to do a version of a traditional whizzer to get a baseline comparison.

2. I still want to play with fine brass screen mesh material, they don't carry it at the craft stores anymore, so I'll have to order some off the Internet.

3. I've had some fun but need to get some projects out the door and make some money. I'll post later when I have the time to resume this experiment.

 

[kach22i]

I have four of these from around 1988, three of them might get "whizzered", although I should experiment on more junk from the recycle store first.

http://s184.photobucket.com/albums/x295/kach22i/Stereo/

 

[kach22i]

Last weeks whizzers.............................

Modified, this weeks whizzers...........................

I have one developed out of this (not posted), one with little parts of everything more or less which I've mounted to my largest scrap driver for further development.

I could tell you which ones do what and how they sound. However if you really want to have some fun you will build your own and find out for yourself.

Because these drivers were in storage for over 20 years or found on the side of the road this spring, I'd estimate that the glues, brass and other materials set me back about the cost of a fill up of gas in my S-10 or vintage Porsche.

100 years ago some guy did the same thing before the mold of whizzer design was cast. They had more fun than the guys doing it on a computer these days - just my opinion.


Sorry no measurements, I'm trusting my ears on this one. I will say that the two-way in the line-up which I added the stove pipe to keeps kicking the one way full range whizzers arse. I'm still hoping to change this and feel there is still a slight chance of pulling it off.

 

[kach22i]

I'm making some progress, the latest effort is not shouty and has some fair highs but the mid-range vocals are a little recessed. Not a bad balance just not as efficient or dynamic as I would like. Therefore I'm considering some alternatives and one of those alternatives includes making my plastic dust cap cover more stiff to increase the highs.

Has everyone seen this?
http://www.madisound.com/manufacturers/accuton/

Madisound also has the diamond membrane tweeter! The dome consists of synthetic pure diamond, a substance even lighter and harder than the corundum used in the ceramics.

What if I brushed on some epoxy to the plastic dust cap and sprinkled some metal or ceramic powder on it?

Link:
http://www.artmolds.com/category187.cfm

I'm sure someone has tried this. .....or not.

So what was the long term results of all the heat and vibration in a loudspeaker environment? More importantly was the result pleasing sound wise?

I don't want to buy a pound of metal dust to find out, but may experiment on what ever I come up with first which is cheap to play with.

I've considered gold leaf from the craft store, but think it would just flake off. Besides all that glue and soft gold may just add mass and not make it any stiffer.