Speaker Builder Experts - A Question on Selecting 15" Woofer Drivers

Hello Anonymous Hero

I designed Hi-Fi speaker cabinets for a speaker supplier and cabinet manufacturer back in the 1950's, basically from "Radiotron Designer's Handbook" written by F Langford-Smith (who remembers that).

That book is available via downloadable sources as an e-book, or on CD - but speaker technology has improved since then.

Your sound quality is dependent on many factors:

1. Size of room
2. Dimensions of room
3. Shape of room
4. Wall and ceiling surfaces
5. Drapes/Curtains, and location of same
6. Location of furniture
7. Furniture materials
8. Floor surface; Carpet, wood, tile etc....
9. Speaker location
10. Location of listener
11. Ears and audio perception of the listener
12. Does the listener have "Cloth Ears"?
13. Other lesser factors....

Remember that the location of bass speakers is not greatly important, as the higher the Audio frequency the easier it is to "pinpoint" the emitted sound. In other words, it is the treble notes which enable direction of sound source to be located.

The cheapest and best low-frequency sound "cabinets" we ever designed were 12 inch internal diameter concrete drain pipes, mounted vertically on the floor, having a sealed base, with a 3/4 inch plywood disperser above the top, similar to an inverted cone/funnel.

The "funnel" did not have any aperture at the lower end, but the up-coming sound from the bass speaker below in the pipe was dispersed from the external surface of the "funnel", which was called, originally enough, the disperser.

The Audio quality was striking, and surpassed even the most expensive bass speaker cabinets from the UK, Germany, or US at the time.

These were painted, of course, so the concrete could not be seen, and many were sold at a good profit.

I seriously doubt whether any of these would be around now, fashions change, and all that sort of thing.

As far as loudspeakers go, there is really no better emitter to hear from, than earphones, because with earphones one ear does not hear the sounds intended for the other, and vice versa.

As far as the drivers you are looking at, whatever you choose, please remember that hearing damage is generally poorly perceived, until it is too late, and the damage is irreversible, unless a miracle occurs.

Kind Regards....

Wow! Yeah, back in the '70s speaker cabinet design was a black art. At the end of that decade two engineers developed a way to quantify a driver and thus created equations for the cabinet design. This moved cabinet design out of the black art domain and closer to the domain of science. The constants are now known as Theil/Small.

Yes, I am very conservative on volume levels. I have no interest in hearing loss. However, I like to overdesign everything on the premis taht if it can perform well at extremes it generally can perform to excellence at lower power levels.

Do you remember the book by G.A. Briggs? He was the speaker expert way back. I built my first speaker enclosure from 3/4" plywood. It was of double wall construction with the space between walls filled with beach sand. A Wharfdale 12" driver was used. This was back in the 50's when "high fidelity" was the buzz word. I remember experimenting with two tape recorders to record and playback in binaural. Syncronizing two recorders wasn't easy, but once done, the spatial effect was astonishing to say the least.

Hello ronseto

An excellent Handbook, like many of those early reference books.

I actually had an early edition of that book, and like others who were also unwise, lent it out many years ago, we later moved cities, and it never arrived back.

<"....Loudspeakers: The Why and How of Good Reproduction
by G. A. Briggs

This easy-to-read and concise introduction to audio basics is something of a classic. Out-of-print for many years (last revised in 1949), the text forms a comprehensive summary of early audio technology with an emphasis on loudspeaker characteristics. Briggs simply and clearly explains impedance, phons and decibels, frequency response, response curves, volume and watts, resonance and vibration, cabinets and baffles, horns, room acoustics, transients, crossovers, negative feedback, transformers, doppler and phase effects, and efficiency. Briggs has a light, breezy style, and a gift for simply explaining difficult concepts.

CONTENTS:

• Quality of Reproduction and Distortion; Development of Loudspeakers; Magnets; Chassis or Cone Housing; Cones; Centring Devices; Impedance; Phons and Decibels; Frequency Response; Response Curves; Volume and Watts; Resonance and Vibration; Cabinets and Baffles; Extension Speakers and Volume Controls; Cinema Speakers; Room Acoustics; Transients; Crossover Networks; Negative Feedback; Transformers and Matching; Comparing Performance; Loudspeaker Life; Doppler Effect; Phase Effects; Loudspeaker Efficiency

1990, 1949, 88pp., 5 1/2" x 8 1/2", softbound

Loudspeakers: The Why and How of Good Reproduction
$6.99....">

If you still need one, the reprint may be obtained from:http://www.soundtechnologiesgroup.com/loudspkrs_good_repro.htm

Kind Regards....

Are you SURE you want 15"s. How about a nice 12" (or 2). 15"s will produce slightly lower base than a 12" but I would never recommend them for home or vehicle installs. I prefer a tighter, more responsive sound rather than a muddy low rumble, besides you can get incredible base if you are careful with your port tuning (or just turn up the volume an extra few dB to compensate, much simpler ).

I wouldn't recommend standard Alpine 12"s or 15"s

I was so disappointed with my 12" Alpine I took it back to the shop the same day and got a 12" JL Audio sub.

Has about 3/4 inch throw and will outperform a 15" Earthquake (not the very high end ones thou).

I built a 12" Earthquake sub into a tuned 50L box, along with a separate amplifier. The parents seem to enjoy it, but they cannot turn it up too loud as it rattles the windows something chronic.

The boxes are made for 15" speakers. I am trying to not have a bonfire party and redo what I have already built.

Designing your own cabinets is not an easy thing to do. It's great to be able to say you did it on your own. The biggest problem is matching components and having the correct crossovers to give the sound you desire.

People always ask me what are the best speakers to buy. This is what I tell them.

Find a good audio store that has a "HOME" setup (carpet, tables, chairs, etc.) and have them switch between outputs with the music playing from a similar unit with your music that you brought with you. Listen to each speaker until you hear what you like and buy them. If they cost $300 you got off easy. If they cost $2300 then you need to decide if this is what you want.

Car speakers will not cut the mustard in a home. They're made for small areas and will loose most of the quality of sound in a large area.

If you already have the 15 inch speakers mounted and wired you probably need to tweak your crossover circuitry to match the desired frequency output to the coils.

Thanks. Tweaking the crossover will no doubt help, but the drivers themselves represent a limit that I would like to go beyond. To get there requires a better driver that will work with the box I have with a minimum or rework.

My thought is that if I can find a suitable driver that better matches the box I can fine tune it with the crossovers and port tuning just as you suggested.

The hunt is on.

How about turning your floor or wall into a giant Subwoofer?

Good luck hunting. I'd start with deciding prices per unit and then look at the response rates and power consumption needed for each. Then it all comes down to hopefully being able to look at the construction and types of materials used. A good tech should be able to explain the benefits and pitfalls of different materials to you. At least your not looking to outdoor installation. Weatherproof speakers can cost a fortune if you want good fidelity.

If your on the space coast like me (I'm in Titusville),there's a speaker designer and builder here in Brevard county.He's done a lot of stuff for me like reconing,amp repair, consulting.He's good and reasonable and can get what you need.call me 267-3541 and I'll hook you up with him.

Thanks!

Since you posted at 3:30AM, what is a good time to call?

Yes, I can use some help.

call anytime, be glad to help,Skip