A real darling. The loudspeaker box that will appeal to everyone.
Recently, I got a couple of pedestal loudspeakers out of the attic to set them up in our living room. My wife’s reaction was, “Oh, those are pretty!” She almost petted them. I thought to myself that this loudspeaker box had that certain something – you know, the famous “wife acceptance factor.” Of course, my wife’s enthusiasm probably had more to do with the small size of the pedestals than with the sound quality.
The boxes were the Daline 3.1 models from Focal, from the 1990s. I’m sure they were good loudspeaker boxes, but the speaker for the deep notes was not especially good for a transmission line. The bass range goes down fairly low, but it is very restrained, and it was hard to fill my 30m² living room with bass sound. In addition, the tweeter, an inverse tioxide calotte, is a little grating because the resolution is so high it overshadows everything else that is going on.
When I saw how the boxes looked in the living room, I was inspired by the small beauties and adopted a few of their elements:
- a similar size, but a little lower
- a transmission line, because I like them
- a small bass mid-range speaker with the same membrane area as the loudspeaker in the Daline 3.1
My goal was not to create an exact clone, but the Daline served as my inspiration.
The weakness of the Daline 3.1 is the principle behind it, in this case the fact that the line does not get narrower, which would improve the Qts value of the bass speaker (which is too small). The Daline from Focal is also not an original idea – Robert Fries described the principle behind it in 1975, in the magazine “HiFi News & Record Review.” It is a transmission line with an integrated low-pass filter in the form of a “pre-volume” filter. Daline actually stands for “decoupled anti-resonant line.” In his article, Fries described a B110 from KEF, which inspired Mahul to build his first loudspeaker – the 5N402 (with the same basket as the KEF), whose neoflex membrane is a variation on the bextrene used by KEF. The loudspeakers were attached to the side of the cabinet. Focal picked up on this principle in the 1990s when developing the Daline 044 assembly kit, which was later marketed as a loudspeaker box under the name Daline 3.1 and serves as my inspiration here.
If hi-fi really is a 90% male market, we have no choice but to make sure that our female partners accept our sarcophagus-sized boxes, even if they long for shoebox-sized speakers and would prefer to hide even those behind a curtain. As soon as it comes to pedestal speakers, the conflict is almost guaranteed. Only a truly loving wife who understands her husband’s pastime will allow them to be set up in a visible location that guarantees the listener’s audio pleasure – naturally with the perfect look, or at least as long as the box in question suits the lady’s mood.
The responses when I ask about my Daline 3.1 “collector’s item” are unanimous: nobody makes anything like that anymore.
The transmission line – or how to get deep notes out of a minus
All right, here it is, our Daline, a real darling (nice pun, right?). It was very freely inspired by Focal’s small loudspeaker box, which had the abovementioned weaknesses but also a few good qualities – and I don’t just mean seducing our loved ones.
The deepest basses under 60Hz were measurable, but in the background; the titanium tweeter, known for its rising frequency curve (despite a high linearity between 2000Hz and 15kHz), can sound a bit harsh. The frequency crossover used mediocre components. In short, the idea was good, the implementation less so.
First of all, not every bass speaker works with the transmission-line principle; second, with a gentler tweeter and above all a crossover that uses components worthy of an audiophile construction, the Daline would be a true high-end box. But the installed 5N412 is not made anymore, and Focal only sells its outstanding beryllium tweeter to itself.
We looked for parts for our Darling in the extensive Seas range, from the Excel and Prestige series, and we found two especially high-quality loudspeakers. We kept the proportions and the bass principle, and the crossover uses high-quality components. Using the outstanding AJHorn program, we simulated the transmission line and were satisfied with the “loss” of a few dB. The Daline claimed 89 dB – an imaginative commercial value, since the measured peak values were only 85 dB. At 85 dB, our Darling offers an acceptable sensitivity that can be handled by any 50-watt amplifier. Obviously, the rules of physics will not let us throw a bass orgy with it, but every manufacturers is subject to the same rules.
For the deep notes, we chose the Seas W15LY001, with parameters adjusted for a transmission line; for the high notes, we used a 19-mm calotte, the 22TFF with impregnated mesh. The W15 has a deep resonance, but it was mainly the very good Qts value of 0.45 that destined it for our transmission line. It goes to just below 50 Hz, which on its own is not a value that would crash stock markets worldwide, but 50 Hz from a TML (transmission line) is by no means a trivial bass reflex loudspeaker. Anyone who has ever heard a box that uses this principle will know what I mean.
The membrane of the 15WLY001 is made of paper, with a Nextel coating to linearize the bandwidth. That preserves the lightness of the paper, but the Nextel compensates for the missing damping by increasing the speed of sound in the material. With its very low moving load of 6.28 g, a suspension made of adaptive rubber allows for a natural “roll-off” (damping at the end of the band). Above all, it is the ambitious magnet system, with copper rings and a T-shaped pole piece, that significantly helps reduce non-linear distortions and modulations while increasing the precision and reproduction of details. The basket, made of cast lightweight metal, has ventilation openings underneath the core that increase the free movements of the membrane.
A traditional fabric tweeter with a good head on its shoulders
Because of its traditional appearance, the 22TFF tweeter has a very large seam and a fairly deep, flawless resonance (1050 Hz). This tweeter, with its ferrite magnet, has a Sonomex membrane – a material developed by Seas and suspended using the same material (in other words, made from a single piece). The voice coil is bathed in low-viscosity ferrofluid. The softness of a fabric tweeter, together with a high resolution thanks to innovative materials, means that the sound of this tweeter fits in well with the logic of a transmission line.
The loudspeaker box
Using the AJHorn software, we were able to precisely define the transmission-line length, the position of the loudspeaker, the starting dimensions and the end of the line. As an additional perk, the cabinet was equipped with a Helmholtz resonator, which reduces the jump in the frequency curve that is so typical for transmission lines. Between 100 and 300 Hz, the TML principle creates what is known as a “comb effect.”
This resonator is positioned right at the top, behind the tweeter. The tube is a simple 50-mm hole, cut out with a keyhole saw. It is insulated with a little bit of Sonofil. Make sure you do not block the opening. At 1.3 meters in length, the line matches the Fs of the loudspeaker, and there is no problem reproducing basses under 50 Hz. The 35 Hz are also still there – a little reserved, but measurable.
In our prototype, the front takes up the entire width of the cabinet (17 cm), for the simple reason that my local hardware store does not normally cut boards narrower than 20 cm. When I casually slid my piece of paper with the measurements toward him, the man behind the saw grimaced. If I had asked for 13.4 cm (the smallest size), he probably would have dragged ME to the saw to cut something else off.
If you want to use a different approach, you will need to recalculate the dimensions. In the picture here, you can see a base that makes the whole thing look better, and it also closes off the filter area (which I filled with sand). All of the walls are 18-mm-thick MDF, with the exception of a few boards inside that were 15 mm thick. Here is the list of board measurements (for two loudspeaker boxes).
MDF boards, 18 mm MDF boards, 15 mm
27,0 x 97,0 (4x) sides 15.0 x 6.0 reinforcement «E»
23,4 x 17,0 (4x) floor/lid 12,0 x13.4 (2x) separator wall «D» for tweeter
23,4 x 13,4 (2x) Helmholtz separator wall 23,4 x 13,4 separator wall «A» for crossover area
97,0 x 17,0 (2x) rear wall 13,4 x 52,6 board «B»
97,0 x 17,0 (2x) baffle wall 13,4 x 6,2 board «C»
22,0 x 32,0 (2x) base
The insulation and damping
We used Tyrofoam(TM), a special heavy foam that comes in 30-mm and 10-mm thicknesses. The photo shows where it is placed. The width is defined by the fact that the board is divided approximately in half, which more or less corresponds to the interior width (slightly less). The mats are attached with hot glue. Then Sonofil strips are cut to a width of 14 cm, slightly more than the width of the interior – that helps them stay in place. The small board “A” is surrounded by some Sonofil, and plugs up the wire channel slightly. That is intentional. Don’t compress it – it should stay loose. The space at the back of the woofer is also filled in with Sonofil (TM). The outlet for the wires should be kept as clear as possible.
Conventional crossover with high-quality components
The crossover is particularly distinguished by its outstanding components, which were carefully chosen. There is nothing to change here; where quality is needed, I don’t cut any costs, and where it is not necessary, I choose components with a good price-performance ratio.
The crossover looks complicated, and it is. But when you look carefully, you will see that C4, C6 and L3 form a 3rd-order high-pass (18 dB/octave); the low-pass with L1 and C5/R5 is forced to 18 dB by the R1/C1 in order to change the coil rating through oscillation. That makes it more “efficient” and increases the rise. I prefer this solution with a single coil over two coils (a true 18 dB), because the second coil increases the resistance, the space needed and the budget. R5 in C5 slightly reduces the rise at the end of the frequency range because C5 is fairly high in comparison to L1. This is intended to prevent the impedance from dropping off too sharply. The RCL branch (C2/C3, L2, R3/R4) is not intended to correct serious defects in the loudspeaker (it has none); instead, it serves as an equalizer. L1 has a weak value that brings the upper mid-range notes to the forefront, and they are reduced by the RCL. The tweeter is too loud, and is provided with sequential/parallel damping by the R2/R6 pair. Finally, C7 and R7 damp the rise toward the high frequencies, which are a bit too penetrating for my taste.
I admit that I am a fan of complex filters, for instance the ones I grew up with in the 1970s, like the KEF and the famous LS3/5a. In contrast to what is commonly asserted, many components are not harmful to the sound as long as they are used properly. You will see for yourself: this loudspeaker sounds “fast,” but it is very linear.
Tuning: If you want to adjust the tone of your loudspeaker slightly, you can play with R7. Reducing its value makes the tweeter sound more brilliant. You can change the tweeter volume using R6. Increasing the value gives it a little more volume.
Do not change the L1 coil – that is very important, since the internal resistance determines the loudspeaker balance!
Frequency and Impedance Frequency under 0°, 15° et 30° Highpass and Lowpass
Phase Step responce Waterfall
Ideally, the wires should be attached to the walls of the loudspeaker box with hot glue to avoid vibrations. After soldering, screw on the woofer with 6 4x20 mm screws, and the tweeter with 4 conical 3.5 x 16 mm screws. Be sure not to over-tighten the screws on the tweeter, or the conical point can break through the plastic on the front panel. But they look good because the head of the screw is flat. The crossover is then installed in its section, which I filled with sand: that eliminates vibrations and makes the loudspeaker more stable. Once the base has been screwed on, using 5 x 35 mm wood screws with conical heads, the loudspeaker is ready to amaze you.
Keep in mind that this is a small loudspeaker and that it can’t produce excessive bass sounds, even if it does impressively reproduce the deep notes. This is a subtle, detailed loudspeaker box, with light deep notes and a good, musical presence. If the recording does not have any low notes, it will not add them, but existing bass notes are reproduced clearly, with color and ease. It is not like a bass reflex loudspeaker that always produces basses even when there are none, and that often seems to play the same note over and over.
I recommend fitting the pedestal with spikes. Intertechnik offers several. Spikes make the loudspeaker more stable, and more detailed in the low ranges. Point the boxes slightly toward the listening area, but not facing straight at you. The slight rise in bandwidth to 18 kHz will disappear at this angle. Mission accomplished.
Without being comparable to it, this loudspeaker makes the original Daline look a little out of date. Set up the boxes in your living room and hope that your wife will reward you for giving her such a nice present.
loudspeakers woofer-midrange: Seas Excel 15WLY001
Tweeter: Seas Prestige 22TFF
Function principle: Transmission Line
Sales and distribution: Intertechnik
Construction: Daniel Emonts
Nominale Impedance: 8 ohms
Damping and insulation: Sonofil & Tyrofoam
Binding post terminals: K11-45AU (Intertechnik) gold plated
ca. Preis: 298€