Custom Speaker Design

This was a omnidirectional tesla looking speaker I built, though there is not relationship to the mechanics of a tesla plasma speaker, it worked. 

However, I used the “it worked” & “was” due to the fact I dropped it! 

I never explained the story of how I laid my hands on a free miniDSP 2x4HD and a UMIK mic... Well it was quite simple really. I emailed them and asked for one.

OK I admit it wasn’t that simple, but it’s not far from the truth. I’ll explain.

Though I’m barely able to sting a sentence together, be it due to dyslexia, crap education in England in the late 80′s/early 90′s or I just don’t notice my mistakes. This hasn’t stopped me emailing random people or organisation asking for help, advise or sponsorship. 

I try to be as honest as possible, stating who I am, what I’m after and most importantly, what it is I want from them. The latter usually required some form of leverage if you are after something, IE give and take.

I’ve been sending random emails out every morning for nearly two years now, though they’re rarely fruitful, on occasions you hit jackpot. My success have included making friends with the “godfather of stencil art”, miniDSP sponsoring me some vital equipment for testing my pet speaker project and a Tête à Tête with a leading loud-speaker manufacture CEO.

No matter what the media want to shove down your throat about how bad the world is, or ignoring the fact that most social media platforms look to be nothing more than data harvesting portals; receiving a response from an email you’ve sent does restore faith in humanity.

miniDSP sponsored me equipment they produce for free, however prior to the initial email I sent, I did build something which was a little out of the ordinary; my omnidirectional speaker. I knew this was a head turner with posting on Facebook and noticing the number of views as well as the engagement rate! 

Omnidirectional speakers use a method of dispersing sound energy in a 360 degree spray, allowing the sound energy to be uniform with its environment.

Unlike a conventional cone driver the reflections from the sidewalls will be identical to the signal that's reaching you directly.

However their are many forms of omnidirectional setups, But my interested is the truest one of all. One which uses a spherical diaphragm that radiates sound vertically. By its design compared with the standard speaker, it changes the vectors of the frequency wave launch by 90 degrees.

The voice-coil is mounted at the bottom and when a signal is applied, it bends the segments, producing omnidirectional sound. 

Why I am building them? Because it’s addictive! Making a speaker enclosure is not making a speaker, rather, it is matching a speaker drive to an enclosure to hopefully produce a harmonious union of the two. Though this is a complex matter, there is nothing quiet like saying I built that - “FROM SCRATCH!”

DIY custom made HiFi Audio Speakers - Omni-Directional - Sparrowlegs Speaker Design.

For those who have never seen my work or my FB timeline - www.facebook.com/SparrowLegsSpeakerDesign/, initially I wanted to build the best audio speakers on a budget. Starting off the first construction was a sealed spiral speaker enclosure. Logarithmic, similar in shape to Bower & Wilkins “Nautilus” - Design by Laurence Dickie.

Why a spiral? Three reasons:

 To test my cabinet making skills

The cabinet becomes a sealed infinite baffle in design, IE it absorbs the speaker drivers rear waves

It looks cool - “Your ears have eyes!”

Moving on to Omni-Directional speakers, this transition evolved simply due to the potential problems an enclosure can produce. Get rid of the enclosure and there’s one less link in the chain. 

Open baffle speaker design has no enclosure, but this doesn’t fit in with SparrowLegsSpeakerDesign’s mantra - “ anything with a sharp edge wasn't conducive to sound reproduction”. 

Omni-Directional speakers was the alternative. (Especially with the tools and materials available).

My custom homemade Omni-Directional speaker - Working! This is what Sparrowlegs Speaker Design has been up to in the recent months.

I'm Titling it - Industrial style changing the shape of home audio reproduction.

Admittedly my place of preference gathering and trading information within the DIY audio world is amongst a group on Facebooks named "Extreme DIY loudspeaker building" - www.facebook.com/groups/1449567115312949/

Mostly everyone there is friendly enough, information and personal builds are  shared, liked and the rest, though I still get lost on the jargon. I would say that there are a few people I have made friends with, though in reality they are still virtual as we have never met!

The misses laughs at me, "Who are you talking to now?" but a guess she don't give me a hard time as it better than being in the pub!

So its 2017, still dyslexic, but still keeping up my hobby building speakers. Over the last year my facebook page which documents my current builds as well as noting resources with I think are of interest, has reached 883 Page likes and 887 followers.

When I changed over from playing with my logarithmic spiral speaker enclosure to investigate Omni Directional speaker motors, this seemed to be a game changer with regards to my online social media presents. However, for example post - www.facebook.com/SparrowLegsSpeakerDesign/videos/1146497162115909

...managed achieved 15K views, but shockingly only 4.5% were women. This to me was and is bad form! 

This post should bring you up to date.

The design was draw on paper, play with different spiral shapes, looking to the longest transmission line in relation to the driver diameter I chose a logarithmic spiral.

Types of spirals - http://en.wikipedia.org/wiki/Spiral

Having an idea of a desired shape of my speaker was all well and good. This is where I didn't realise that I had chosen an artistic route for my design opposed to a scientific one.

Let me explain, I started planning out the form of my creation, thinking about aesthetics and using my basic understanding of forces and sound reflection as well as, construction techniques and materials. What I hadn't factored in was speaker driver parameters and the impact the shape would make on the finished sound.

If you know the T/S parameters of driver you’re going to use, this will then dictate the shape of the case. As I had already chosen the shape, reverse engineering was the only way to choose the correct driver. http://en.wikipedia.org/wiki/Thiele/Small http://www.webervst.com/spkrcalc/para.htm

After many initial drawings, I managed to draw a spiral with a transmission line of 2.8m with an driver 8" (20cm) speaker driver. This for me was a good ratio, and perfect for turning 720 degrees. (More turns = more transmission line reflections with smaller obtuse angles. - This wouldn't have been good).

So, at the beginning of august I went about researching how to make a pair speaker cabinets. This shouldn't have been to difficult.

1. Cut 6 sides of wood. 2. Make 1 to 3 holes 3. Insert some cool looking drivers (speaker cones - Woofers, midrange and tweeters). 4. Connect to an amp and annoy the neighbours.