Fountek FR89EX

After working out my plan for a killer mini two-way system using the miniDSP and two miniAMPs, I decided that I wanted to explore the sub-sat (2.1) option a little further to see what could be accomplished in an even lower-cost system. This option in particular can meet the “can’t the speakers go on the wall?” scenario. Here again are the configuration options for the miniAMP: 4 x 10W into 4 ohms 2 x 20W into 8 ohms 1 x 20W into 8 ohms and 2 x 10W into 4 ohms. For a sub-sat system, option (3) is wanted. The drivers are best chosen withRead More →

Seas U16RCY/P

After modeling what feels like a hundred mid-woofers, I have decided on the drivers for a new active two-way speaker. It will, of course, use a miniDSP as crossover, but this time I am going to use it in “preamp” mode, and furthermore add the miniAMP module. The aim of the project is to see what I can come up with that is along the lines of a “lifestyle” system but which also satisfies some fairly demanding “audiophile” requirements. The idea is that it isn’t going to have to be placed out into a room – as many of you probably know, the reaction yourRead More →

Earle provides a series of photographs for the Thunderbird build, showing his recommended parts layout step-by-step and details of construction methods. I like to get the “big picture” in my head, so I sketched out Earle’s recommended component layout on paper from the photographs. I then figured that since the Thunderbird is a good candidate for trying some parts swapping and tweaking, I’d modify the layout a bit so it would be a little easier to access and replace certain components. I don’t really know how other people do it, but drawing up a layout is something that I like to do with a notepadRead More →

Weston Thunderbird parts

The Weston Acoustics Thunderbird is a kit amplifier from Earle Weston. This is a single-ended amplifier that by default uses two KT88 tubes, but can be biased (by changing the cathode resistor) to several other tube types. I first encountered the amp a couple of months ago at Terry Jones’ get-together in Bathurst, and took a couple of photographs of it. Since I already own one of Earle’s amps (the Trinity Signature), I decided to order and build up the Thunderbird kit as a complement. The topologies of the two amps are quite different (the Trinity is push-pull and valve-rectified whereas the Thunderbird is single-endedRead More →

miniDSP balanced audio DSP

I’ve been reading a bit about the use of multiple subwoofers to improve bass response and/or to reduce spatial variation in the response. In particular, the paper “Low-Frequency Optimization Using Multiple Subwoofers” by Todd Welti and Allan Devantier shows how placement of multiple subwoofers can be used to optimize response or spatial variation. They document the results from running a search algorithm over a multi-dimensional space defined by: The particular combination of subwoofers selected (two or four out of eight, in the most interesting part of the paper) The gain of each subwoofer The delay of each subwoofer The frequency and cut of a singleRead More →