That sounds like an interesting system with 3' ribbons etc. Sometimes I mis-wire systems also. I assume your talking about having a driver with reversed polarity. I have a small AA battery with short wires soldered to the ends for quickly checking to see that all the low frequency drivers are in phase with each other.
Yes my GP measurements are usually about 80 ft from the closest object. I will sometimes run a gated sweep above 300Hz then splice that curve into a GP curve. I live about 10 min drive from the offices of both Linear X LMS and also AP (Audio Precision). Those are companies that make / made speaker test equipment in Oregon (as you probably know).
I thought they were done but didn’t know if someone had got that ball rolling again.
Sorry for the divergence.
Thank you.
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
I am running LEAP on XP so not sure how much longer it will work. This thread might help if you get into a bind!
https://www.diyaudio.com/forums/soft...dows-10-a.html
Unfortunately there is no support even for the last versions which is a shame it's such great program!
Rob
"I could be arguing in my spare time"
There's a few reasons I can think of why this isn't common;
- Flat to 20 hz anechoic means extremely bass-heavy speakers in-room. Each boundary in proximity might give up to 3 dB per octave room gain below 100 hz.
- You can have any two combination you like of extension, small cabinet and sensitivity, but you can't have them all. Hoffman's iron law. Sacrificing sensitivity is not a very good idea and flat to 20 hz means huge box.
M2 isn't flat to 20 hz, not by a long shot. Still, they require me to drop the 4,7 dB EQ boost at 21,5 hz AND to shelve down the bass by about 4 dB below 50 hz in my room to maintain a somewhat of a Harman-type in-room curve.
This is the reason it's common to design in about -3 dB oct shelving from around 100 hz - to account for real rooms.
Too much bass makes everything sound bloated and puffy, drowning all details in the music.
What is feasible in terms of F3, cab size and efficiency has been established by R.H. Small since the seventies in Vented Box..., Part 1, p. 324 widely circulated on the Net. There is no magic unfortunately.
Small's chart below gives the details on this. Increasing pic size after saving it could make it easier to read the description under the chart (Fig. 16).
Note that according to Eargle's Loudspeaker Handbook 1% efficiency is equivalent to 92 db/1W /1M sensitivity (half space, piston band). 2% = 95 db and 5% = 99 db, with most speaker systems at around 1-2%.
Not a whole lot, but the cost of Watts is relatively low compared to the old days...
Richard
Although I have a friend who has passive speakers that are relatively flat down to 20Hz (anechoic) and they sounded well balanced in his listening room. Maybe it is hard to generalize because each room is so different acoustically. Possibly other people can give there opinion. Maybe I am in the minority on this one.
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