I've never personally heard the PM220's, so take this with a grain of salt, but from what I've read here, or maybe it was PETT, they are a hot mess and not worth trying to use.
On a completely different note: while I've built quite a few tube amps, none of them were flee watts. My smallest tube amp is the one that sits in my office at work. Pure Class A with 6V6 output tubes and 8 kOhm output transformers. It puts out an honest 3 watts/channel. I designed a pair of small desk speakers that use the ND91-4 and those little Peerless DX20BF00-04 tweeters. They're about 0.2 cf ported. After BSC they are roughly 80ish dB/2.83v/m. I can tell you that low power / low sensitivity combo is still quite impressive in my 15' x 20' office space. Grant it they are only 28" in front of me.
JMO... I feel like having full BSC on a low powered speaker is kind of like pushing in that old "Loudness" button on some receivers. It just makes listening at lower volumes more enjoyable. I could be in the minority on that though.
I think there is a place for it. A good small speaker used in the near field can be an amazing listening experiance.
I'm really proud of my MAC-04 build; they have plenty of baffle step and will rock the desk top. At CSS we proved they are not for meeting halls. 😆
I was criticized for not sharing build pictures last year, so got some wood cut today. Those shelf boards from Menards are a bit chippy. Just reminder to center your router bushing to the bit.
Indiana is the 1.5 challenge so no tweeter and an insertion point no higher than 1K for the .5 woofer(s). I have substantial overlap but with enough smoothing it looks under 1K. F3 of 45 in 10 liters!
Comments
Not sure I like the triangle port. However, it's probably better than putting the port next to the tweeter.
From what i recall someone did some testing and found high distortion from triangle port compared to the other typical shapes.
Four small triangular ports, one in each corner?
I don't remember that, but did recall a bunch of extra squiggly lines in FR when next to a tweeter.
I've never personally heard the PM220's, so take this with a grain of salt, but from what I've read here, or maybe it was PETT, they are a hot mess and not worth trying to use.
I think you might be referring to Scott Hinson's paper "Loudspeaker Port Nonlinearity Testing or Just Port it" found here: https://www.facebook.com/story.php?story_fbid=1212863525554986&id=100057174291834
On a completely different note: while I've built quite a few tube amps, none of them were flee watts. My smallest tube amp is the one that sits in my office at work. Pure Class A with 6V6 output tubes and 8 kOhm output transformers. It puts out an honest 3 watts/channel. I designed a pair of small desk speakers that use the ND91-4 and those little Peerless DX20BF00-04 tweeters. They're about 0.2 cf ported. After BSC they are roughly 80ish dB/2.83v/m. I can tell you that low power / low sensitivity combo is still quite impressive in my 15' x 20' office space. Grant it they are only 28" in front of me.
Side port a no go?
Craig, thanks. That means I can't screw this up to badly. Do you remember how much BSC you took?
Probably not. I like a symmetrical speaker but that might need to be a compromise.
Damm I didn't think it was that bad. OK round port it is, somewhere...
How about a long oval port the width of the cabinet?
** Never mind - I just glanced at Scott Hinson's paper.
Full 6 dB. They don't have the benefit of sitting close to the back wall.
Shelf is 12" high? How wide? Can't do a lay down style, tweeter to the side?
Yeah I thought about just laying down a normal speaker but the off axis is terrible. Probably crossing in the 2K range.
Are they really for critical listening?
small coaxial/MW combo out of the question?
Good point, still want to try to make it fit.
I'd love to do a coax, but I'm using up my stock. I have that small KEF coax from JR, but the sensitivity sucks.
Current concept drawings. I'm liking B.
B is definitely better, but I like the triangle port in the corner the best.
Slot port ?
The offset would help smooth out baffle diffraction profile too.
JMO... I feel like having full BSC on a low powered speaker is kind of like pushing in that old "Loudness" button on some receivers. It just makes listening at lower volumes more enjoyable. I could be in the minority on that though.
I think there is a place for it. A good small speaker used in the near field can be an amazing listening experiance.
I'm really proud of my MAC-04 build; they have plenty of baffle step and will rock the desk top. At CSS we proved they are not for meeting halls. 😆
I was criticized for not sharing build pictures last year, so got some wood cut today. Those shelf boards from Menards are a bit chippy. Just reminder to center your router bushing to the bit.
Despite the pain to cut out I'm really liking how the hexagon FaitalPro drivers look.
These speaker are not as small as I thought at 15 liters
Here's a sneak peak at my Indiana entry
MTM with all the same drivers or a full range and 2 woofers? Looking forwatd to see where this goes.
Indiana is the 1.5 challenge so no tweeter and an insertion point no higher than 1K for the .5 woofer(s). I have substantial overlap but with enough smoothing it looks under 1K. F3 of 45 in 10 liters!