By way of light relief from the 45 amp I'm well overdue an update on this.
Since building the speakers around 18 months ago I've been using cheap class D 3116 amps below 180Hz with built in low pass filters with the SB subs, then the 208Es above with the GM70 amp with internal highpass filter, and the T90As above 5kHz with another class D 3116 amp and a simple second order filter. The 285GMFs haven't been in use at all. And I've really enjoyed it. So much so that I haven't exactly got my finger out with the active crossovers to get the 285s running.
The 3 way Linkwitz-Riley boards are built and wired up (and yes, I did use a nasty LED lighting SMPS to get me going) and feed the 6 channels of 3116 class D amps. Probably around £40 to £50 all in for 6 channels including PS. They are on the face of it not bad at all, though there is some hiss. But they have that slightly unrelaxing quality that means they wouldn't stand the test of time. But they were only meant to get me going too, not a long term solution.
So I have:
SB subs with a low pass at 65Hz
285GMFs 65Hz to 415Hz
208EZ highpass as 415Hz with natural roll off around 5kHz
T90A with a simple second order passive filter off the 208s at 5kHz
I established before that as the room is quite small there are probably a lot of reflections and room issues in the plots, and it's clear I'm not a measurement engineer, but here are the averaged plots for the listening position and from 1m away.
- All 4 drivers 2m listening position REW averaged 8 readings.jpg (123.69 KiB) Viewed 1482 times
- All 4 drivers 1m REW averaged 8 readings.jpg (121.48 KiB) Viewed 1482 times
After a little listening to tune the sound in by my ears this is what I measured
- All 4 drivers 2m listening position ear adjusted.jpg (89.5 KiB) Viewed 1482 times
Initial listening was interesting. There have been a lot of changes so it's a little tricky to work out what's changed, but I've heard detail in familiar recordings I've never heard before, and that was from mp3s. And there's a proper weight to instruments like a grand piano.
I think the next job is to try with some decent valve amplification and see what happens then. Then perhaps think about some passive filters to replace the active crossovers. And maybe some room treatment.
I'm interested in people's thoughts on the plots, those far more experienced than me at looking at these things.