etude TL speakers


"etude" is a musical term which literally means "a study." It refers to a piece of music that was created for artistic or skill development purposes. As my first serious speaker project, they have had considerable value as "a study!"

Why DIY?

My visits to Hifi shops convinced me that a sound system that I would be happy with would cost a lot more than I was ready to pay. I was more impressed with the value for money in loudspeaker kits. For those in Melbourne, Australia, I recommend looking at The Loudspeaker Kit.  More kit suppliers can be found in the resources section of this site. Later I found a kit available at Jaycar. It used similar drivers to the Loudspeaker kit flagship speaker, but it was available without the cabinet. It was cheaper, and proved to be an advantage as I wanted to make my own enclosure. The end result was very satisfying in terms of sound quality and value for money. For $1000 I created a loudspeaker that I consider equivalent to commercially offerings costing $5000.

Some of the advantages of DIY:

lower cost

An equivalent commercial speaker would have cost 2 - 5 times as much. If not for my DIY approach, I would have had to accept a less impressive speaker

ability to cater to your own aesthetic goals and tastes

If you want curves, then create curves! Or make a speaker that matches the decor of your room.

Gold plated binding posts, heavy duty cables, bi-wire or bi-amp capabilities, brass spikes, grilles without grille clips (they use magnets concealed under a veneer), real wood veneer or very tough hard wearing automotive paint.

It is cheap and easy to manufacture rectangular boxes. A DIY enthusiast can attempt speakers that may be very expensive to offer commercially due to their size or construction difficulties. For many, DIY offers an affordable entry into many less accessible designs including transmission line, horns, open baffle, infinite baffle and a large number of alternatives.

satisfaction in listening to speakers you have built yourself

Gold plated binding posts, heavy duty cables, bi-wire or bi-amp capabilities, brass spikes, grilles without grille clips (they use magnets concealed under a veneer), real wood veneer or very tough hard wearing automotive paint.

The drivers

Tweeter:  1 x Vifa  D25AG 1" aluminium dome
Midbass: 2 x  Vifa P17 6.5" polycone

Information on these drivers can be found on the Danish Sound Technology website, which is the parent company of Vifa, Peerless and Scan Speak. These are considered by many to be among the best value for money drivers available to DIY speaker builders. The midbass driver has a good bass response, reasonable efficiency and power handling, and a reasonably flat freqency response, which makes it suitable for a first time DIY project. The D25AG tweeter is a well regarded tweeter, however I found it to be a little bright. While this tweeter is a good match for the two midbass drivers in terms of efficiency, I intend to replace it with a more efficient Morel  MDT 37 textile dome tweeter. This will be part of a later bi-amp upgrade. The extra efficiency won't be wasted when configured this way.

Measurements for the Vifa midbass driver

Note the dimension of the voice coil to the faceplate for time alignment purposes.

Deep, natural bass

The 1.2m high enclosure has a folded transmission line with an effective length of 1.8m.  As a transmission line, the bass has the same F3 as a conventional vented design, but with a more gradual bass roll-off. The result, when combined with room gain which gives bass boost if positioned correctly, yields a very deep bass response. In a small room, these speakers have bass extension similar to a subwoofer. The bass is less punchy than a vented alignment, but is more natural sounding and more satisfying with music where you want to hear subtlety and musicality in the bass. The result is particularly satisfying with acoustic bass.

Construction - how to make it happen

The enclosure was constructed of 18mm MDF. Thickness varies from reinforced single layer 18mm to 36mm on the front where the drivers are mounted. MDF is relatively soft, so the base was made of hardwood. I originally constructed a rectangular box, but later decided I wanted it to be more "sculptural." Adding the curves was painful! I added a 12mm sheet of MDF and spent 10 hours planing it down to a curve by hand. I spent about the same time with a belt sander to get the curve right. Actually it took about that long for me to give up and ask the resident handyman (aka "dad" who has more skill, experience and patience than I do). I don't recommend building a speaker the way I did it - making changes along the way is not something I would do again. It isn't  without reason that I called this speaker "etude!"

How NOT to build a speaker

In terms of construction, this speaker illustrates "how not to build." If you are like me, you probably skim though the detailed construction tips that other DIY websites have! Still, if you want to avoid some of my mistakes:

be patient! most mistakes come when you say to youself that you want to "JUST DO IT!" and then you do, but the "it" is not the "it" that you had in mind
plan first, even if you are not the planning type! work out how you will build it, resolve the details, do a test or a quick prototype, find out how much it will cost

Please note:

The dimensions shown are internal as they are the ones that are critical. This is constructed out of 18mm MDF with 12mm sheets added to get the curve. The front baffle is double thickness for the top half, the bottom half actually just has thickening, although not represented here. There is also a brace from the rear or the box to the middle wall, not shown here. I have also added a few other small braces, such as to the corners and one under the top of the box. The internal width of the box should be 174mm, which gives an outer width of 210mm with 18mm MDF. This also works well visually. If you make it too wide, the drivers start to look small relative to the size of the enclosure. You may even wish to make it narrower. Small changes like this will not be audible. Without the curves, 18mm MDF works fine without bracing and will come to about 20 kg. With the hardwood base I added and the extra bracing and thickening and curves, it now weighs 33kg! It's hard to say whether the difference is really audible or not. It really comes down to that word "obsession." The fact that when you build a speaker yourself, there can be a certain level of satisfaction, a certain improvement in sound that your brain automatically creates, when you know you have that added element of overkill!... keep in mind that 33kg is quite heavy and if you want to make it heavier, allow the cost of visits to the Chiropractor in your total budget! (yes, I actually did have to visit the Chiropractor after moving this speaker around a lot!)

So how does it sound?

If you are like me, you have probably skipped to this point - "just show me how it looks and how it sounds!"

First impressions: neutral sounding, surprising detail and clarity, very natural and deep bass

This is a well-rounded and capable speaker that is well suited to many types of music. Bass extention and musicality is it's most impressive achievement. While many claim that bass below 40 Hz isn't necessary for music, these speakers have convinced me that this is not true. I have a number of CDs with significant output below 40 Hz (and no I'm not into organ music). I have used these speaker for home theatre in a small room and there was no need for a subwoofer. Soon after I had built the enclosures, I listened to a single sealed Shiva subwoofer in a larger room and was surprised to find that the Shiva was working to its limits to match the depth and SPL of my TL's. Given the different rooms, it is not a fair comparison, but it made me realise that I would need to consider other alternatives to achieve the bass I wanted for home theatre in a large room.

In general, this speaker does everything well. The clarity and detail are convincing, and they image well. They are very enjoyable to listen to.

A critical view

After 100 hours of listening I started to notice one particular weakness. The treble is quite bright. I'm convinced it has to do with the metal dome tweeter. Combined with my NAD 2200 power amp, which is known to also be bright in the treble, the result was unpleasant at higher volumes. I believe that this is due to both the characteristic sound of the tweeter and power compression. This is the only real weakness of this speaker. It suprised me to find that this criticism could not be made when heard at low volumes. When I sit in my listening chair and listen at fairly low volumes, I turn the lights out and the speakers disappear and I merely enjoy the music.

Planned upgrades

I plan to eliminate the brighness and power compression problem in the treble by removing everything that causes this problem:

NAD 2200 power amp
This will be used to power the woofers. The strength of this amp is in the bass - very tight anc well controlled yet with a soft natural quality. I will remove the crossover and bi-amp. For the tweeter I will use an amp that is softer, possibly a DIY class A.

Vifa D25AG metal dome tweeter
This will be replaced with the Morel MDT 37, which has much higher power handling (200 watts) and sensitivity (93db SPL). This tweeter, as a textile dome will be softer and sound more relaxed given the extra power handling and senstivitiy.