Back in October of last year I started to play with Raspyfi. I was impressed by everything except the name so I’m pleased to report that Raspyfi has changed its name to RuneAudio. They’re clearly working hard to improve their offering as their latest newsletter shows but still no mention of DLNA.
Not only is one watt too loud for the home but guitar speakers are not designed for home use. Guitar speakers are largely designed to be stuck into open-backed cabinets which means they are incredibly sensitive to placement. It’s fine if you’re up on stage with a few feet behind the cabinet but at home you’ll want to push your amp out of the way – up against a wall or in a corner – and that will cause the sound coming out of the back of the speaker to bounce around and interfere with the sound coming out of the front of the cabinet. The frequency response of the system – including the room – will be “lumpy” with some frequencies being affected more than others.
The way to fix this is (obviously) to put the speaker in a closed back cabinet but guitar speakers are designed for use in an open-backed cabinet so require a relatively large closed-back cabinet to provide a sensible frequency response. Jensen provide a good range of small speakers that ought to work well in a domestic environment and they publish the Thiele-Small parameters required to design the cabinet. Celestion don’t do either; they have one eight inch driver and that’s as small as they go. Celestion do not appear to publish Thiele-Small parameters.
What does this tell us? It tells us that products aimed at guitarists are remarkably conservative; in many ways they haven’t changed much over the decades. Guitar amplifiers first appeared in the 1930s/1940s which is around 30 years before Thiele and Small published the results of their study into the parameters that were important to the design of a loudspeaker enclosure. Designers back then were working blind so no wonder they left the back off the cabinets; all resonance problems were solved immediately (as long as you kept the cabinet in an unconfined space).
So how do you build a speaker cabinet for a guitar that will work well in a home environment? The answer is not clear to me yet but I want great tone at an acceptable volume and I want to be able to play along with acoustic instruments without dominating the sound so I’m going to have to sort it out. Perhaps the best idea is not to use a guitar loudspeaker at all but this is a bit radical and I do like the sound of Jensen speakers. While I’m pondering this, here are a couple of interesting articles on the subject of guitar loudspeakers:
- Choosing Guitar-amp Speakers (SOS)
- Building and Designing Speaker Cabinets for Guitar and Bass (Duncan’s Amp Pages)
Note that the Duncan’s Amp Pages article suggests a Qtc should be between 0.707 and 1.0. This is the hi-fi approach but cannot be achieved by any of the traditional Jensen speakers below 12 inches in diameter as the Qts is greater than 1.0 (and the Qtc cannot be less than the Qts) . The modern Jet series creates some exceptions to this but the smallest Jet speaker is 10″ in diameter which, I would argue, is too large for home use.