Hi folks,
Haven't been active on the forum for a while, been busy building. i finally got around to building the speakers for my home theatre. Still building at the moment but here are some pics. Measurements will come later but i've included sims, design etc. Speakers are wharfedale 4" with apex jr tweeters. Paint hasn't turned out very good but it wont matter as i'm putting on grills. The speakers are all going to be wall mounted with the front 3 in a baffle. I'll add more info later
Haven't been active on the forum for a while, been busy building. i finally got around to building the speakers for my home theatre. Still building at the moment but here are some pics. Measurements will come later but i've included sims, design etc. Speakers are wharfedale 4" with apex jr tweeters. Paint hasn't turned out very good but it wont matter as i'm putting on grills. The speakers are all going to be wall mounted with the front 3 in a baffle. I'll add more info later
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thanks dave, i considered that initially but that would only become an issue with a longer line or closer listening distance.
The graph in my post is at 2.5m i.e the listening distance with 20volts. When i was designing i originally designed them with 9 drivers but the high frequency roll off was too low to mate with the tweeters unless i moved the listening position further back. The room is 5 meters long so this puts me perfectly center. I've attached a graph of the 1 meter on axis in blue vs 2.5 meter in black to show what i mean. Tapering would work but i would lose efficiency. One of the requirements was to achieve 105db at the primary listening position crossed at 80hz and within reasonable excursion limits. Initial listening tests and rough and ready measurements with an ipad app sound spectrum analyser exceeds this with about 20 volts (100 watts). I could have curved the speakers to narrow the sweet spot and remove combing but im afraid my building skills wouldn't be up to it.
The graph in my post is at 2.5m i.e the listening distance with 20volts. When i was designing i originally designed them with 9 drivers but the high frequency roll off was too low to mate with the tweeters unless i moved the listening position further back. The room is 5 meters long so this puts me perfectly center. I've attached a graph of the 1 meter on axis in blue vs 2.5 meter in black to show what i mean. Tapering would work but i would lose efficiency. One of the requirements was to achieve 105db at the primary listening position crossed at 80hz and within reasonable excursion limits. Initial listening tests and rough and ready measurements with an ipad app sound spectrum analyser exceeds this with about 20 volts (100 watts). I could have curved the speakers to narrow the sweet spot and remove combing but im afraid my building skills wouldn't be up to it.
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I forgot to add the crossover from the tweeter to the mid takes into account the intrinsic high frequency roll off with the mids as a low pass so the actually crossover at the moment is just a half decent 4.8 ohm cap on the tweeter line. This equates to a 1st order high pass at 9200 hz which is high enough to negate any nasties hitting the cheap tweeters. The mids are actually crossed at 120hz in the sim, ive attached a pic with no crossovers.
Heres a materials bill
wood - free
mids - free birthday present / £120 for 64
tweeters - £30
caps - £10
Ports - £10
paint - £20
Screws - £2
Total £190 for 7 speakers and i have more drives if i want to do 11.1
Heres a materials bill
wood - free
mids - free birthday present / £120 for 64
tweeters - £30
caps - £10
Ports - £10
paint - £20
Screws - £2
Total £190 for 7 speakers and i have more drives if i want to do 11.1
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