Another Idiot

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I remember years ago when Dick Pierce used to state, "Any idiot can design a loudspeaker and unfortunately, many do." I suppose it was only a matter of time before I finally embarked on a journey to prove him correct.

In order to help other beginners, I have summarized my initial experiences below.

After reading the diyaudio forums for a while, I became enchanted with the siren song of the simplicity of full-range speakers. In order to start as inexpensively as possible, I bought a pair of Dayton Audio RS100-8 4 inch full-range speakers and Denovo 0.04 ft^3 knock-down MDF cabinets from Parts Express. I felt it was not a bad deal for less than $85.00.

The first mistake I made was mounting the drivers smack dab in the center of the front panel, which is not the ideal location. The next mistake was trying to stain MDF. The results were not pretty. Although it was not unexpected, I was surprised how much bass was lacking.

I made a second pair, this time using the similar RS100P-8 with paper cones. I did not notice at the time that these were not touted to be full-range, only "perfect for use as a woofer, midwoofer, or dedicated midrange driver." I mounted these drivers on the centerline a bit above the middle. I used black spray paint instead of trying to use stain. Felt pads on the bottom prevent furniture scratches. They turned out better in appearance. The missing higher frequencies are not a huge problem since I can no longer hear much above 10 kHz.

As I pondered how to address the missing bass frequencies, I stumbled upon the whole baffle step diffraction issue. I ordered some resistors and inductors and decided that 3 dB compensation sounded more natural to me than 6 dB. Of course it depends on how far from the back wall you expect the speakers to stand. I used 2.7 ohm resistors and 0.4 mH inductors from Parts Express. I mounted them on perf board inside the speaker using a screw through the center of the board. Though this improved the bass quite a bit, I am continuing my full-range quest by trying larger diameter drivers in a larger boxes.

I will keep you posted on how it goes. :)
 
I tend to cover my cabinets in thin carpet, it hides a multitude of sins.
I also tend to use full range drivers as it saves messing around with cross overs.

My first attempt at a pair of speakers luckily turned out very well.
It was two cabinets with a pair of Fane 12-50WRMS drivers in each.
Worked well on a mobile disco for many years.

In more recent years I got a bit braver and got into w bins, not quite full range but good enough for my living room.

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Joined 2012
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Welcome to the world of full range Barry Allen!

If you want some nice bass and a great sounding speaker, try dabbling with foam core speakers. They can be made for $1 or so, uses a razor and straight edge, a kitchen table or a carpeted floor to build, and hot melt glue gun.

Make the 0.40x scale Karlsonator with the plans offered in Post 1. Put your RS100-8 in it, either one will work.

Mini Karlsonator (0.53X) with Dual TC9FD's

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Alternatively, put your RS1000 in an XKi, that is my desktop computer speaker and it sounds great. No lack of bass and super wide sound field.

465542d1423880510-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-rs100-stereo.png


The measured response shows it goes down to about 55Hz when placed on desk with a wall behind it. Not bad.
461843d1422331652-xki-xs-ab-initio-karlson-6th-order-bandpass-xki-rs100-4-tape-neweq-polar.png


If you should want to make these out of wood, be careful that they will not sound as good unless you line the interior with lots of padding (my favorite are melamine reticulated sponge pads). The foam core absorbs back reflections ncely, and wood equivelent sounds "boxy" without lots of damping.

If you buy the $6 a sheet Elmers brand foam core vs the $1 store it looks better and is more durable. Harder to cut as cardboard facing is thicker.

More info on Foamcore speakers here:

Foam Core Board Speaker Enclosures?

Some other good low cost full range drivers to try:

Dayton PS95-8
Dayton PA130-8
Faital Pro 3FE25-8 or -16
Vifa TC9FD (8ohms)
Vifa TG9FD (8ohms)

I must have made two dozen speakers with TC9FD and it works amazingly well for a simple speaker.
 
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