There were many design goals that we met in the design of the Triptch kit speaker- the complexity of reaching all of these goals whilst creating a beautiful design led to many hours of design iterations using state of the art 3D modelling software.
Below is a description of the design and technology incorporated in the design.
There are differing opinions about time alignment, its audibility and therefore it necessity.
We believe that there is a great body of reputable papers that have proven that time alignment brings real benefits to our perception of sound reproduction. Drivers all emit sound at a different point in space located along the voice coil (in traditional “dynamic speakers”). Determining this offset and then accommodating it in the speaker baffle allows the sound from multiple drivers to reach the listener simultaneously which goes towards simulating a single source rather than multiple points creating sound.
The effect of this time discrepancy can be subtle and some argue, inaudible. We contend that it has a subtle effect on the listener, specifically in reducing fatigue over long listening periods due to the reduction in the requirement for the listener to sub-consciously adapt for the discrepancy.'
Minimal Baffle refraction ripple effects through Tapered / complex baffles:
With the exception of certain enclosure types most speakers consist of an enclosure that loads the front mounted speakers in such a way that the bass output of the drivers is augmented by either the air trapped behind the drivers (sealed / infinite baffle) or the effects of an additional pipe that is tuned in such a way to augment the bass output below the resonance of the driver (ported). The laws of physics dictate that the bass output of the drivers will be amplified down to a range of frequencies determined by the width and height of the baffle. Below this point, designers refer to the output as “baffle step loss”.
In simple enclosures that have sharp and regular (parallel) edges to the sides, top and base of the enclosure, there are a series of ripples that occur in the total response of the speaker referred to as “baffle refraction” or “baffle refraction distortion” to be more precise.
There are many papers that discuss the effects such as those by Oslen and Linkwitz - http://www.linkwitzlab.com/diffraction.htm.
The design of the front of the triptych is the result of a desire to reduce or mitigate these refraction effects through the use of non-parallel and tapered edges that even out the ripple size and spread it out across a wider range of frequencies thus “averaging” the ripples that exist. This gets us towards the “perfect” enclosure within the constraint of needing to make an affordable, easy to construct DIY kit.
Sealed versus ported enclosures. Port placement. Room integration:
Like every aspect of high fidelity sound reproduction, there are differing views on the advantages of sealed or ported enclosures as well as debate about the placement of ports.
With regards to the view on whether ported or sealed is superior, we would suggest you consider 2 things – what you prefer personally and secondly, what works best in your listening room. From a purely engineering point of view, ported speakers will generally offer greater bass extension than the same driver, in a similar enclosure that is sealed. On the flip side, a sealed enclosure with trade this off with (generally), better power handling at lower frequencies and better room integration as the slower roll-off of the bass output can interact with the bass reinforcement of the listening room. Since we believe there is no “right” or “wrong” you can simply add stuffing to the port and transform it into a sealed box – we invite you try both to see which you prefer and which works best in your room.
We decided to place the port of the front of enclosure for a number of reasons. Firstly, a front firing port will tend to integrate better with the room in contrast to a rear firing port. On a qualitative note, personal listening has lead me to the opinion that a front firing port that is located as close as possible to the driver is preferable – though others may disagree or not perceive a difference. In the instructions, we advise you to position rolled up acoustic foam behind the port in the enclosure. This will mitigate any standing waves that can form along the length of the port.
Off-axis smoothness & consistency:
Whilst most loudspeaker manufacturers (and some reviewers!) offer up on-axis response as a way to quantify a loudspeaker’s performance, a real-world speaker needs to interact with the listener and the room in which it is situated.
Studies have been conducted into the subjective responses in trained listeners to even versus uneven off-axis responses of loudspeakers. It has been concluded that there is a strong correlation between smooth off axis responses and an increased perception of accurate and expansive soundstage along with an increase in the listeners long term enjoyment of a given speaker design.
For further reading, refer to works of Floyd Toole, Atkinson (Stereophile), Martin Colloms. http://www.harman.com/sites/default/files/white-paper/12/11/2015%20-%2006%3A20/files/LoudspeakersandRoomsPt2.pdf (page 18 onwards)
Separate sub-enclosures - increased detail through mechanical isolation:
This is a no-compromise design that incorporates many design features to allow the drivers to create sound unimpeded by vibrations, refractions from the baffle and standing waves internally.
High frequency drivers operate inside a narrow bandwidth and require as little vibration in order for them to offer the best levels of fine detail. The midrange is essentially a small woofer and its output will interact with the pressure waves from the woofer so separation ensures that the midrange is free to move independent of the other drivers.
In a similar way, crossover components require a vibration free environment as micro-phonics has been found to affect the performance of the crossover. Micro-detail improvements in a speaker offers better low-volume resolution as well as an increased ability to (amongst other things) pick up ambient cues and timbre in instruments. This is often interpreted as good imaging depth and offers a wider envelope to listen to the speakers within and reduced fatigue as you are not forced to listen at higher volumes to appreciate the speaker.
Inert and extensively braced enclosures:
Extensive internal bracing has been strategically placed to dampen resonances throughout the enclosure. There is extensive vertical and horizontal bracing around the critical crossover, midrange and tweeter sections.
The front baffle consists of sculptured triple-sandwiched 56mm MDF that provides a dense fixing point for the drivers.
The cross-bracing also features offset openings to stop pipe-resonances inside the enclosure and an angled brace behind the woofer stops early reflections bouncing back to the woofer which due to the time offset of the reflections will cause smearing to the sound.
3 way designs - some advantages:
The classic 3 way design offers some interesting opportunities. The bass, midrange and treble functions can be better split up so that each specialised driver can be used in its intended bandwidth. This can also mean that for a given crossover point, there is less distortion caused by out-of-band resonances in the drivers.
A small midrange driver allows a higher crossover point than would be possible with an 6”-8” driver as there is better off-axis response at high frequencies as well as a generally smoother response. 6” woofers will often have a crossover point at around 3000hz and an 8” driver may require a crossover point as low as 1500hz. These points are inside the critical midrange where the ear is most sensitive to frequency (and perhaps more importantly), phase aberrations. The crossover points for the Triptych are nominally 600hz and 6000hz and their high order (steep falloff) means that the drivers have a narrow region over which they overlap and interact acoustically. This results in a locked-in sound that blends the output of the 3 drivers into one body of sound.
Predictable impedance with gentle phase angles.
The speaker has a 4ohm minimum impedance which is easily handled by any competently designed amplifier. The impedance gently rises at both frequency extremes as this presents the gentlest load on any amplifier and ensures the best stability under heavy loads.
The degree to which the actual impedance varies and steepness at which the phase shifts (phase angle) over the frequency range can present difficult loads to amplifiers as well. Some amplifier technology such as valves and Class-D exhibit a modified frequency response as they drive “difficult” loads. The Triptych exhibits smooth phase angles no greater than +/- 35 degrees and has a fairly shallow set of peaks and troughs in the impedance.
High quality / good value drivers and crossover components:
We feel that the triptych is a sensible balance of high quality enclosure, low distortion drivers and transparent crossover components.
Whilst some manufacturer’s concentrate on one aspect of the design, perhaps to the detriment of others, the Triptych incorporates a sensible approach to selection and design that provides a sensible price to performance proposition.
The drivers are sourced from SEAS in Scandinavia. This company has been manufacturing high quality drivers for over 65 years. The most impressive feature of their drivers is their value for money and excellent consistency the latter of which is of the highest importance for a DIY kit.
The crossover components have been exclusively sourced from Jantzen in Denmark. Again, this is a company with a history of making excellent value components that whilst not having a exotic construction (and resultant price tag), provide an excellent presentation.
The Triptych uses wax inductors to the midrange which offer even higher levels of transparency. The capacitors in series with the midrange utilises Superior-Z capacitors which offer an astounding insight into the midrange. Another feature are the Silver-Z capacitors in series with the tweeter that offer an incredibly fast and detailed treble with no harshness. Rest assured, the choices settled on were not based on bling factor or bragging rights - they were based on hour upon hour of testing, swapping components and measurements.
On the ancillary front, we have gold plated high quality binding posts, silver plated internal Teflon coated wiring, flared ports and specially chosen internal acoustic baffle.
Subjective notes (the non-scientific bit):
On a personal level I believe the choice of drivers and the crossover design attains some attractive outcomes. The bass is deep and powerful and due to the stiff paper cone, gives great control whilst offering just a hint of warmness.
The mid-range is an advanced polycone (CURV) design that is very stiff and offers high internal self-dampening. The smaller cone size allows a number of advantages but on a subjective level, the midrange is the centre-piece of the design and crossover components offer a very high level of detail with no harshness or glare. The use of a higher crossover point and time alignment of the drivers results in a seamless transition between the mid range and treble range.
Careful tuning of the crossover allows a highly detailed midrange and a dynamic sound whilst the tuning of the woofer gives deep but clean bass response.
The tweeter offers great off axis response and has a stiff dome with good internal damping. I feel that the treble is non-fatiguing but detailed and creates an enveloping sound field.
The Triptych has been tested with a wide range of amplifiers (of just about every variety of topology) and quite a few front-ends (DAC's, CD players, streaming devices) as well as a wide selection of speaker cables and other variables. This is ensure that is sounds good with a wide range of gear from budget no-frills amp's to $8000 exotic ones.