Corner loading it is!
Quadral midrange
And combined nearfield and horn opening (in corner) all horn opening responses are adjusted so that the peak output is level with the highest output of the driver, so they are combined but not properly summed in these graphs
The very high quality CSX 5.5" woofer that should have an Fr of 48 Hz
The next one is a shielded Peerless I go on a sale at Parts Express 10 years ago
And finaly the responses at 2m
That is 2 m from the corner so the distance to the driver is a bit shorter, this is not the same corner as priviously. Why the hornmouth response of the Quadral has more 40 Hz output but less at 2 meters I do not know
A breif listening suggest better slam but then I have it in an other corner and other drivers, so that is for other builders to find out.
I think this will be the end of this research of the CBLH the restart of the Dorspen One BC project.
Quadral midrange
And combined nearfield and horn opening (in corner) all horn opening responses are adjusted so that the peak output is level with the highest output of the driver, so they are combined but not properly summed in these graphs
The very high quality CSX 5.5" woofer that should have an Fr of 48 Hz
The next one is a shielded Peerless I go on a sale at Parts Express 10 years ago
And finaly the responses at 2m
That is 2 m from the corner so the distance to the driver is a bit shorter, this is not the same corner as priviously. Why the hornmouth response of the Quadral has more 40 Hz output but less at 2 meters I do not know
A breif listening suggest better slam but then I have it in an other corner and other drivers, so that is for other builders to find out.
I think this will be the end of this research of the CBLH the restart of the Dorspen One BC project.
Last edited:
As a noobie I have no idea what the graphs mean,good or bad. Credit is due Dr Boar as fast moving and well educated in the art of the audio. Can any one help me by recommending a good book or two?
I've been meandering though this unfathomable swamp called audio for a few weeks now. I'm not ashamed to acknowledge I know little of what I read.
A question is- is sound absorbing ceiling tile every used for sound damping in a speaker.? I have had very good results with this in Muffler design on reducing noise levels in Shop Vacs Mufflers. Cars have used them for years.. The Helmholtz resonators can easily be made that can be variable tuned. This might be of assistance in matching a speaker to a room. I was not aware speakers used these.
I've been meandering though this unfathomable swamp called audio for a few weeks now. I'm not ashamed to acknowledge I know little of what I read.
A question is- is sound absorbing ceiling tile every used for sound damping in a speaker.? I have had very good results with this in Muffler design on reducing noise levels in Shop Vacs Mufflers. Cars have used them for years.. The Helmholtz resonators can easily be made that can be variable tuned. This might be of assistance in matching a speaker to a room. I was not aware speakers used these.
Welcome to the world of diy speakers - you are in for a lot of fun...
There is some good reading in the technical papers by MJK on his website Quarter Wavelength Loudspeaker Design.
The use of ceiling tile is used extensively by @hm as internal partitions inside his horns.
http://www.hm-moreart.de/1.htm
Here are some scans of the Dinsdale papers.
http://www.metaleater.narod.ru/Dinsdale_Horns_1.pdf
http://www.metaleater.narod.ru/Dinsdale_Horns_2.pdf
http://www.metaleater.narod.ru/Dinsdale_Horns_3.pdf
Last edited:
I would not go for the Dinsdale papers as they only cover horns and are quite dated by now, that is the recomended drivers are not avaible any more and things like Thiele Small parameters are not discussed.
There is a lot on the net and if you want it collected in a book
High Performance Loudspeakers: Martin Colloms: 9780470094303: Amazon.com: Books. It might be in larger libraries as well.
I have the first and second edition, the current one is the sixth.
If you find books from the 1950-1970s DIY loudspeakers, you build boxes and screw drivers into holes of the boxes and make a crossover from a table or simle formula. Computer simulations and gated response measurement that costed millions in the 1970s can now be had with free software and a microphone for 100 dollars.
The upside is that we now are so much more in controll of the design and building of DIY speakers, the down side is there is a technical maze to get lost in. It is still just a tool to listen to music and have some fun building it. (Smile)
There is a lot on the net and if you want it collected in a book
High Performance Loudspeakers: Martin Colloms: 9780470094303: Amazon.com: Books. It might be in larger libraries as well.
I have the first and second edition, the current one is the sixth.
If you find books from the 1950-1970s DIY loudspeakers, you build boxes and screw drivers into holes of the boxes and make a crossover from a table or simle formula. Computer simulations and gated response measurement that costed millions in the 1970s can now be had with free software and a microphone for 100 dollars.
The upside is that we now are so much more in controll of the design and building of DIY speakers, the down side is there is a technical maze to get lost in. It is still just a tool to listen to music and have some fun building it. (Smile)
Dr Boar,
Thanks for tip on book. I will check i tout.
I was warned that the Dinsdale papers have errors - but nonetheless useful for understanding some of the same overall goals of speaker building.
The software for modeling has been a paradigm shift - just like sims for camera lenses have made modern optics so good and free of trial and error.
A very good flat-response microphone for purposes of designing speakers can be had for $2 (Panasonic WM61A capsule ) and the software is free (Holmimpulse). Very nice product and great tool for diy'er.
John Conover: Using the Panasonic WM61A as a Measurement Microphone
HOLM Acoustics
Thanks for tip on book. I will check i tout.
I was warned that the Dinsdale papers have errors - but nonetheless useful for understanding some of the same overall goals of speaker building.
The software for modeling has been a paradigm shift - just like sims for camera lenses have made modern optics so good and free of trial and error.
A very good flat-response microphone for purposes of designing speakers can be had for $2 (Panasonic WM61A capsule ) and the software is free (Holmimpulse). Very nice product and great tool for diy'er.
John Conover: Using the Panasonic WM61A as a Measurement Microphone
HOLM Acoustics
I just completed a test box of this design and loaded it up with a tang band W5-1611. Using test tones I found it to have good output to about 45hz before rolling off. Have not had time to run a FR sweep yet. I found that it needed BSC, and running it filterless it sounded pretty thin. However with some BSC in place it sounded good and it's clear that the horn/TL is doing its job. I'll try and post measurements and a picture or two in the coming days.
I had thought so too, but it sounded very thin out of the gate. 3db of bsc around 500hz up balanced things out (I was not being terribly scientific about the whole thing). MJK's article seems to hint at this, though I wasn't sure:
How are the horn loaded? A corner with flimsy plaster walls as is common in the US really is a very different corner than a brick/ concrete wall corner. I did measurements with corner horns comparing true concrete corner to one with concrete floor and side wall but backwall in 1/2" plaster wall. I do not have the graphs at hand but as I recall at 80 Hz downwards I lost about 6 dB.
Good to see other builders trying them out
Good to see other builders trying them out
Here are the hand plotted graph I made in the 80s! The test tone is warbled by a 8 Hz sinus tone so 50 Hz really is 42-58 Hz. It appears that the losses start below 100 Hz and then give -4 to - 6 dB down to the 40 Hz drop off of the horn itself.
To what extend this apply to MJKs BLH and how much improvement is to be had by having double plaster walls or shorter stud distances is anyones guess. But I have experience in other plaster walls and just doubling the plaster to 2x 12mm gave a far sturdier wall.
To what extend this apply to MJKs BLH and how much improvement is to be had by having double plaster walls or shorter stud distances is anyones guess. But I have experience in other plaster walls and just doubling the plaster to 2x 12mm gave a far sturdier wall.
DrBoar - if I might suggest that use of the term "plaster" might be a bit misleading, as the density of the material itself, and backing substrates would be quite different from the now far more commonly used "gyproc" / "drywall" board.
Not all drywall materials, even of the same thickness are created equal, and within the past few years new formulations have been developed with sound deadening qualities.
But you're certainly right in that 2 layers of 1/2" or even 5/8" standard drywall on 16" centered 2x6" wooden studs will provide a much more rigid surface than single layer on 24" centered lightweight metal studding that is more commonly found in none load bearing walls than you might be aware of. Just ask an installer of wall mounted upper cabinets in commercial office spaces.
Not all drywall materials, even of the same thickness are created equal, and within the past few years new formulations have been developed with sound deadening qualities.
But you're certainly right in that 2 layers of 1/2" or even 5/8" standard drywall on 16" centered 2x6" wooden studs will provide a much more rigid surface than single layer on 24" centered lightweight metal studding that is more commonly found in none load bearing walls than you might be aware of. Just ask an installer of wall mounted upper cabinets in commercial office spaces.
This is interesting. I am corresponding with another European who was mentioning 6mm plasterboard. Is this a common construction practice? I believe that my 35yr old house has 1/2" drywall on 16" center 2x4's. I think that this is still standard practice. 5/8" drywall is also commonly available.
Bob
Bob
Here in Holland, plasterboard is rarely used for walls. It's mostly brick and concrete for outer walls and "gass cell concrete" or solid gypsum blocks for interior walls. Old houses have wooden floors, after about 1975 it's almost all concrete. Plasterboard is usually used for false ceilings, or quick and cheap remodelling.
When we see footage of an American town that's been destroyed by a hurricane, we always wonder why they build their houses in such a fragile way. Perhaps the reason is cost, easier to rebuild after such extreme natural violence. I have to admit that I'm not sure our concrete and brick houses would hold up much better.
But anyway, lots of concrete here and so lots of roomgain.
When we see footage of an American town that's been destroyed by a hurricane, we always wonder why they build their houses in such a fragile way. Perhaps the reason is cost, easier to rebuild after such extreme natural violence. I have to admit that I'm not sure our concrete and brick houses would hold up much better.
But anyway, lots of concrete here and so lots of roomgain.
I don't have a good pair of corners, unfortunately. I'm running a 2.1 FAST setup with a sealed sub now and am considering building a monster of a cornerhorn to go replace that sub. Sort of the last sub I am going to make. But it has to be superflexible and superextended in range to really be the last sub I am going to make. I have an idea, but it's not ready to be published yet. And I need help...
Drywall is used in inner walls apartments and houses. Henceforth I will use "drywall" as "Gyproc" is a brandname. 6mm drywall is used for refurbing rough surface before painting or putting up wall paper. At 6mm the structural strengh is not much. The standard stuff of drywall is two sheets of thick paper/ cardboard with plaster in between. Then there are variation that are harder, fire resistant, weather resistant and so on. The accoustic installations I have seen by gyproc and knaufdanogips use standard drywall board but the attachment kit creates an elastic monting.
Speaker and amp are finally home, and my initial concerns about BSC appear to have been unfounded based on listening tests in my room. Bass response is very good. Here's a FR graph from close to my listening position, so this represents a LOT of room interaction. There's also a chance that the placement of my stereo is actually choking the horn output. I'll post a picture of the horn and its room placement soon...
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.