Background: I'm considering a 4-way project, it will be an existing 3-way
cabinet with an added (sub)woofer in a separate box, one (sub)woofer
per channel.
The three original drivers will all be playing in passbands that are
nowhere near their resonant frequencies. This would be without
changing the original crossovers. All I'm really doing is stealing the
lowest frequencies away from the original woofer, thus turning it
into a low midrange.
Questions: If I understand this right, there will be no "tuning" box volume
requirements for each of the three original drivers. So, could I remove the
back of the original cabinet altogether ? Open-back midranges supposedly
sound "cleaner", but what is the price for this, is it lower power handling
before their max cone travel is reached ? Should the low midrange be
somewhat walled off from the upper midrange, even though they both
would be open-backed ?
General questions: If you increase the enclosed volume behind any
midrange driver that is not playing near its resonant freq, can you
predict what will happen to sound quality ? The larger you make the
enclosed volume, the closer you get to open-backed, so what is the
tendency of the resulting sound, does it keep getting softer yet
crisper/cleaner ?
Thanks much for any help and clarification !
cabinet with an added (sub)woofer in a separate box, one (sub)woofer
per channel.
The three original drivers will all be playing in passbands that are
nowhere near their resonant frequencies. This would be without
changing the original crossovers. All I'm really doing is stealing the
lowest frequencies away from the original woofer, thus turning it
into a low midrange.
Questions: If I understand this right, there will be no "tuning" box volume
requirements for each of the three original drivers. So, could I remove the
back of the original cabinet altogether ? Open-back midranges supposedly
sound "cleaner", but what is the price for this, is it lower power handling
before their max cone travel is reached ? Should the low midrange be
somewhat walled off from the upper midrange, even though they both
would be open-backed ?
General questions: If you increase the enclosed volume behind any
midrange driver that is not playing near its resonant freq, can you
predict what will happen to sound quality ? The larger you make the
enclosed volume, the closer you get to open-backed, so what is the
tendency of the resulting sound, does it keep getting softer yet
crisper/cleaner ?
Thanks much for any help and clarification !
All I know for sure, is that you have to take reflections from the wall behind the speaker into account.
When I tried an open midrange chamber, I had to many reflection, because my speakers where to close to the wall of my room. This gave unwanted colorations in the midrange sound.
If you have alot of room and maybe more than a couple of meters to the rear wall behind the speakers in your listening room, then the reflection will be dealyed enough, so that the ear can seperate the direct and reflected sound, and chances for succes are bigger.
Dampening the rear wall is also an option, but this can be tricky to tune correctly in the lower midrange.
I learned it the hard way, that the listening room is a huge player when you try to judge performance of a particularly speaker driver in a specific cabinet design.
I play with a closed cabinet right now, with all my drivers, and is very happy with the sound.
I've heard good open designs, but they all had more space behind the speaker, than they had in front of it.
When I tried an open midrange chamber, I had to many reflection, because my speakers where to close to the wall of my room. This gave unwanted colorations in the midrange sound.
If you have alot of room and maybe more than a couple of meters to the rear wall behind the speakers in your listening room, then the reflection will be dealyed enough, so that the ear can seperate the direct and reflected sound, and chances for succes are bigger.
Dampening the rear wall is also an option, but this can be tricky to tune correctly in the lower midrange.
I learned it the hard way, that the listening room is a huge player when you try to judge performance of a particularly speaker driver in a specific cabinet design.
I play with a closed cabinet right now, with all my drivers, and is very happy with the sound.
I've heard good open designs, but they all had more space behind the speaker, than they had in front of it.
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But remember to make the cabinet as deep as possible. This will help to delay the reflections from the rear cabinet wall. These reflections "travel" back through the membrane of the speaker driver and hereby distorting the sound. Thats why a little to big is better than a little to small, especially when it comes to midrange cabinets. When well damped, the overall shape of the cabinet should be less important.
No, there is a limit. Too large of an enclosure might cause new problems.
Also the nearby open backed drivers isn't a perfect solution.
That approach works fairly well. The old '70s classic, the Dahlquist DQ-10 did that and managed to get surprisingly good midrange out of the Philips AD5060.
An externally hosted image should be here but it was not working when we last tested it.
Not a speaker for those who hear with their eyes, though.
Didn't have these things either. We did have stuff my father would build, until I entered the picture nothing was all that hifi but did sound well rounded in what it could do low level. When he designed our new home one thing he did was to have me install a 100 twisted pair, punch down blocks and all for future use (computers he's wouldn't shut up about 
. Intercom, whole house sound using IB speakers I designed for an 8th grade science project. That was '77
What we did have from an early age was the latest hightech. Open drum video recorder in '67, Calculator '70 for example. Most of my friends parents were engineers working at WrightPat R&D. Another, Roger Reihl, elementary school friend, father designed the worlds first solar digital watch (reihl time corporation). That was 1970 I think... anywho it wasn't that he did this first, but how he did this first. Their attic was converted into a cleanroon lab where pops made his own IC's from scratch! Now they all had they high end stuff I was exposed too.
. Intercom, whole house sound using IB speakers I designed for an 8th grade science project. That was '77What we did have from an early age was the latest hightech. Open drum video recorder in '67, Calculator '70 for example. Most of my friends parents were engineers working at WrightPat R&D. Another, Roger Reihl, elementary school friend, father designed the worlds first solar digital watch (reihl time corporation). That was 1970 I think... anywho it wasn't that he did this first, but how he did this first. Their attic was converted into a cleanroon lab where pops made his own IC's from scratch! Now they all had they high end stuff I was exposed too.
I did some comparing, between some bookshelf speakers and a Goldwood GM85/8 sealed back midrange. The GM85/8 is low distortion but has a muffled sort of sound. Then I disabled the tweeter on my Linaeum Pro LX-550 and tested the 5 1/4" Kevlar woofer as a midrange. It blew them all away, with a nice clear, full bodied midrange. I had recently put new surrounds on the Kevlar woofers, it gave them slightly more brightness. A welcome change.
I think I'm going to use the two Kevlar woofers from my Linaeum center channel and build a chamber for them. Problem is a 5 1/2" deep, 7 3/4" tall, 6" wide back will eat a lot of my 1.7 cf cabinet. It is a sealed box woofer, so maybe I can get by. Or maybe I can reduce the midrange chamber since I am not using it for bass, only from 800 to 5khz or maybe 8khz, where the GM85/8 is crossed now. Using the GM85/8 to 8khz seems to give the cymbals a fuller bodied sound.
I think I'm going to use the two Kevlar woofers from my Linaeum center channel and build a chamber for them. Problem is a 5 1/2" deep, 7 3/4" tall, 6" wide back will eat a lot of my 1.7 cf cabinet. It is a sealed box woofer, so maybe I can get by. Or maybe I can reduce the midrange chamber since I am not using it for bass, only from 800 to 5khz or maybe 8khz, where the GM85/8 is crossed now. Using the GM85/8 to 8khz seems to give the cymbals a fuller bodied sound.
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When grinding a speaker open it is a huge help to put a plastic bag over the magnet and fold it over. Rubber band it down. Then when done, pull the fold up and trap the metal shards in the bag.
I hope to spend some time today testing the Kevlar driver, but it is 6 ohms , my xover is 8 ohms. The donkey steps on my foot again.
I hope to spend some time today testing the Kevlar driver, but it is 6 ohms , my xover is 8 ohms. The donkey steps on my foot again.
Well the Kevlar midrange made a world of difference, bur the .8 cf enclosure for it cost me lots of deep bass. Sealed enclosure, the bass is still there but sounds sort of thin now. Tradeoffs, sigh. Empty box is 1.7 cf.
I was running a sealed back mid, 800 - 8000 hz, silk dome 8000 hz to 20k+, the highs are stunning. Especially cymbals. Now since I am crossing at 5khz the highs are not as accurate but the mids are excellent. Maybe I need to work up some sort of low midrange helper cone speaker. A four speaker system.
I was running a sealed back mid, 800 - 8000 hz, silk dome 8000 hz to 20k+, the highs are stunning. Especially cymbals. Now since I am crossing at 5khz the highs are not as accurate but the mids are excellent. Maybe I need to work up some sort of low midrange helper cone speaker. A four speaker system.
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could be due to the high Fs
I guess its right in the middle of roll off slope
makes a passive xo very tricky
easier to have lower Fs
I did some ear scanning and found my peaks were from the woofer being crossed too high. It was up into the midrange. I dropped the woofer-mid crossover to 650hz from 800, and now all is well, I'm ok with it, after having gone back to the sealed back midrange.
I couldn't match the Linaeum woofer to the Goldwood mid or tweeter without specs or mic. I found the Linaeum woofer and tweeter work together easily, and the Goldwood mid + tweeter worked together well. Mixing them gave me problems.
Crossing at 650hz also gave a very pleasant surprise, no beaming. Dispersion came out so well I can barely sense any beam when walking across the front.
I couldn't match the Linaeum woofer to the Goldwood mid or tweeter without specs or mic. I found the Linaeum woofer and tweeter work together easily, and the Goldwood mid + tweeter worked together well. Mixing them gave me problems.
Crossing at 650hz also gave a very pleasant surprise, no beaming. Dispersion came out so well I can barely sense any beam when walking across the front.
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