The Ariel is an efficient transmission line designed by Lynn Olson which is well suited for use with low output ‘single ended triode’ valve amplifiers. Please follow the link for all details of plans mentioned here. Originally designed in 1993 it has since undergone a number of modification stages, primarily prompted by feedback from the large number of DIY enthusiasts who have constructed them.
The design is basically a twin transmission line layout to support a D’Appolito format. The twin transmission lines dictate that this project requires a degree of application and it is therefore hoped that this article will not only give an insight into construction, but also help in deciding whether the necessary tools and skills are available at the outset.
I wont pull the wool here, this is a fairly complex cabinet, comparable to a folded horn. For this reason I would recommend the minimum set of tools to be a table saw(with accurate cross-cut fence), a good router, a vernier gauge and a clean work bench of at least 4 feet by 2 feet. If the table saw does not have a precise cross-cut fence then a large capacity mitre saw(8-12inches wide) is a must. The skill required to construct these speakers can be summed up simply as the ability to cut wood exactly square and to precise lengths. In addition to the woodworking skills there is a requirement for some very simple soldering. Two minutes with the plan reveals the need for templates. To mirror match the cabinet sides would be very difficult without. 3/8 inch ply is used here for templates.
Having cut and checked all the panels, the next stage is to route all the rebates for the internal partitioning. The templates will obviously have been cut to suit whichever guide bush has been chosen for the task. Depth of cut is not crucial here but 6mm gives a pretty strong build.
For the internal partitioning the method of construction will be entirely down to individual preference. The method adopted here was to lay one side panel on the workbench and glue the back panel to it, waiting for it to dry. All joints were made with PVA . Assembly was then a matter of inserting 1, 2 or 3 internal partition pieces at a time. Before gluing the partition pieces in place, they were positioned and the other side panel laid on top to ensure a good fit. Once lined up, the partition pieces were glued into the side that was lying on the workbench, with the unglued side replaced on top while the glue set.
The internal partition pieces can be rebated or but-jointed to each other. If but-jointing (as in this case) the jointing obviously has to be precise. As the angle of the joints varies between 30 and 75 degrees this can obviously pose some problems because the standard mitre saw will only cut to 45 degrees. To address this problem an adjustable mitre jig was designed/constructed to allow the joints to be cut with the router.
The crossovers can be built to personal preference. In this case the circuit was built from 2.5mm mains wire on drilled veroboard as shown in the photograph. The units were securely located and wired into the empty space at the top of the cabinet before the top was glued into place.
There is a plethora of opinion which can be read, just follow the links from Lynn’s Ariel pages. In addition, opinion seems to be polarised, some people love ’em and some people hate ’em so I won’t stick my neck out.
I will say that I have been running them for many years in my project recording studio where they are driven by my Single ended EL34 amp of about 6 watts. I have no complaints whatsoever, they tackle any type of program thrown at them, the imaging is razor sharp and presentation very neutral to my ears, which is ideal as I use them primarily for mix monitoring. In short they are one of the most invisible speakers I have had the pleasure of……..
If you fancy the challenge, and I thoroughly recommend it, then good luck.
The above constitutes a precis from my original review in HiFiWorld from April 2005 which may still be available in the archives