Well my semi ob's sounded very good. The bass reflex sub with the AD12200w was a great addition to the system. Without it yes it sounded thin because the baffle was very narrow.
I think the MLTL direction is the right way. On the Dutch forum there was great success with the AD12100m in a MLTL.
R.
You're welcome!
Same-same. Doing a quick sim using a couple of different sets of specs, a MLTL ideally needs to be really large to go low at high acoustic efficiency, which is typical for vintage drivers, so it's going to be about how big can you 'afford'.
This ~144 L MLTL has an F3 in the mid 50s, so to get it down into the low 40s will require it to be twice as big and 3x to get down into the 30s, so.......
how big are you willing to 'afford'?
GM
Tough one, the speakers we have in use now is a standmount 7" scanspeak and 1" seas dome wich has a f3 at 42hz so I would like to have the same reach but not at the expense of having something that huge in my livingroom. So 50hz will have to do, hopefully we will not miss those 8hz to much.
Hello @ll,
nice to finde a thread about these vintage 12" Phillips drivers.
I'd like to introduce to you another cabinet I found in an blog:
Please you a translater to your language, blog is in german:
2A3 Maniac: Hochwirkungsgrad: Lautsprecher mit Philips AD 1255/M7 (AlNiCo) 12" Breitbänder
2A3 Maniac: Lass schwingen, Alter! Skizzen für die Reso-Kisten aus Tonholz mit Philips AD 1255/M7
It's sort of BR as mentioned some postings above.
May be someone find's an impression or new idea when lokking at that project.
nice to finde a thread about these vintage 12" Phillips drivers.
I'd like to introduce to you another cabinet I found in an blog:
Please you a translater to your language, blog is in german:
2A3 Maniac: Hochwirkungsgrad: Lautsprecher mit Philips AD 1255/M7 (AlNiCo) 12" Breitbänder
2A3 Maniac: Lass schwingen, Alter! Skizzen für die Reso-Kisten aus Tonholz mit Philips AD 1255/M7
It's sort of BR as mentioned some postings above.
May be someone find's an impression or new idea when lokking at that project.
So the cabinette is suposed to sing? Isnt the 12" cone enough, do we need to make the cabinette a "cone" as well, how do we control it? I'm really confused about the design, more then I was befor.
But I have to say that it is a lovely looking speaker. Does it have any merits or is it just a wild project!? Wouldnt mind building them if they where an good option for the ad12202.
But I have to say that it is a lovely looking speaker. Does it have any merits or is it just a wild project!? Wouldnt mind building them if they where an good option for the ad12202.
Hi Pepe
And the wood in original version is expensive - others built violines or cellos from it
So "thin" plywood will work - wasn't their a recommendation in the text or comment of 12 to 16mm plywood ?
Also "wood core plywood" or "blockboard" (sorry - isn't my motherlanguage, the german word is "Tischlerplatte" ) will be an alternative - or something else.
Feel free for your one version.
well, i think the "original" is proposed to do....
And the wood in original version is expensive - others built violines or cellos from it
So "thin" plywood will work - wasn't their a recommendation in the text or comment of 12 to 16mm plywood ?
Also "wood core plywood" or "blockboard" (sorry - isn't my motherlanguage, the german word is "Tischlerplatte" ) will be an alternative - or something else.
Feel free for your one version.
Yes, large Altec and others consumer cabs were designed similarly, including some of their prosound and studio monitors to passively 'bleed off' excess cab pressure due to being under-damped alignments plus it took the 'burden' off manufacturing to build/assemble to a high accuracy and properly seal up a cab as well as reduce size, weight, hence cost as much as practical, especially since the components were so heavy.
This one being just long enough to have sufficient 1/2 wave vent damping due to being tapered [ML-horn or ML-TQWT depending on who you ask] combined with an inherently well damped vent would normally be quite over-damped, so letting it 'sing' a bit is a good plan when properly designed, 'voiced'. This one's nice looking too.
GM
If one choose to build one cab from blockboard and one from plywood. Wouldnt they have totaly different sound and/or even resonansfrequency? Maybe that is the same thing in this case.
I googled phy/hp and found the occelia speakers whom seems to use the same principle, but they strengthen the boards on the inside in a honeycomb fashion, but not hexagonal insted they use squares. This way you should get a stiff but lightweight panel that do not sing as much nor store much energy. But will theese small square compartmwnts mess upp the speaker design if applied to any given speaker project?
I googled phy/hp and found the occelia speakers whom seems to use the same principle, but they strengthen the boards on the inside in a honeycomb fashion, but not hexagonal insted they use squares. This way you should get a stiff but lightweight panel that do not sing as much nor store much energy. But will theese small square compartmwnts mess upp the speaker design if applied to any given speaker project?
In short, yes; but it depends on what you mean by 'blockboard'. Locally, we have 'butcher block' made from thick hardwood strips and 3/4" thick pine boards made from strips or pieces.
Butcher block is technically superior to no void plywood panels due to greater rigidity and mass, so in the end neither will have any obvious sonic signature once the plywood is braced sufficiently to match since both will have an Fs well above the speaker's upper mass corner [2*Fs/Qts'].
The pine panels are relatively soft, though the ones made from pieces are a bit more rigid due to 'finger jointed' construction, so require significant bracing in the form of either an attached rigid back panel or made of very thick pieces since rigidity increases at thickness^3 to push its Fs high enough.
The 'honeycomb' stiffeners seems a bit overkill, but then I don't know the specs of the wood panels. Regardless, I imagine they are rigid enough to not 'sing' beyond what the cab's eigenmodes do reflecting off the back of the driver.
GM
Butcher block is technically superior to no void plywood panels due to greater rigidity and mass, so in the end neither will have any obvious sonic signature once the plywood is braced sufficiently to match since both will have an Fs well above the speaker's upper mass corner [2*Fs/Qts'].
The pine panels are relatively soft, though the ones made from pieces are a bit more rigid due to 'finger jointed' construction, so require significant bracing in the form of either an attached rigid back panel or made of very thick pieces since rigidity increases at thickness^3 to push its Fs high enough.
The 'honeycomb' stiffeners seems a bit overkill, but then I don't know the specs of the wood panels. Regardless, I imagine they are rigid enough to not 'sing' beyond what the cab's eigenmodes do reflecting off the back of the driver.
GM
Out of curiosity, what was the xo point of the br subs? Did you run the ad12202m8 wide open?
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Hi
https://www.google.de/search?q=tisc...2&ved=0ahUKEwj0srLG76TLAhWkQJoKHYcxCowQsAQIIg
or
http://www.holzwerken.net/Blog/Heiko-Rech/Eine-Lanze-fuer-die-Tischlerplatte
pictures will speak for themselves
this material:
https://www.google.de/search?q=tisc...2&ved=0ahUKEwj0srLG76TLAhWkQJoKHYcxCowQsAQIIg
or
http://www.holzwerken.net/Blog/Heiko-Rech/Eine-Lanze-fuer-die-Tischlerplatte
pictures will speak for themselves
OK, this construction is used for inexpensive 'solid' core doors around here, but not in thinner sheets AFAIK. Don't know their respective MOE, but are pretty stiff due to being 1.25-1.75" thick.
Tapping on my 1.75" thick front entry door with it as hard up against the door jam as I could shove it, it 'rings' similar to my known sufficiently rigid, braced 0.75" marine grade plywood constructed ~20 ft^3 cabs when tapped with a hammer, so my SWAG is that a baffle or cab made from my door stock would perform quite well with no obvious cab 'color' due to a lack of sufficient rigidity. Cost wise, 18 mm BB ply is cheaper, so see no benefit overall.
If available in much thinner panels, I'm assuming they will be relatively 'limp', so would 'color' the sound, ergo best suited for damping high Qt drivers.
GM
Tapping on my 1.75" thick front entry door with it as hard up against the door jam as I could shove it, it 'rings' similar to my known sufficiently rigid, braced 0.75" marine grade plywood constructed ~20 ft^3 cabs when tapped with a hammer, so my SWAG is that a baffle or cab made from my door stock would perform quite well with no obvious cab 'color' due to a lack of sufficient rigidity. Cost wise, 18 mm BB ply is cheaper, so see no benefit overall.
If available in much thinner panels, I'm assuming they will be relatively 'limp', so would 'color' the sound, ergo best suited for damping high Qt drivers.
GM
Found this on the harbeth speaker forum:
"What underpins the BBC's thin-wall cabinet philosophy (and I was surprised to read that exact word in one of Harwood's papers recently) is the observation that a perfectly cast bell will ring on for many seconds. Conversely, a bell with a hairline crack will sound leaden and hardly ring at all. It's the same with cabinets: if the panels are all rigidly glued together then at some critical frequency or other a note or notes in the music will trigger the cabinet's natural structural resonance. In such a rigid structure, there is nothing that can be done to suppress the ringing - and each time that note reappears, it tops up the ringing which then becomes a permanent drone underneath the music.
Conversely, in a thin-wall cabinet, the lossy joints (i.e. removable baffle/back and the generally 9-12mm thin panels used throughout the box) each act as an acoustic hairline crack. They inhibit the build-up of resonance. Simple as that really!"
If this is true then maybe I should build a mltl out of 12mm plywood. Then they should be relatively easy to move around and I could afford to make them quite large since they could be pushed back against a wall when not in use.
"What underpins the BBC's thin-wall cabinet philosophy (and I was surprised to read that exact word in one of Harwood's papers recently) is the observation that a perfectly cast bell will ring on for many seconds. Conversely, a bell with a hairline crack will sound leaden and hardly ring at all. It's the same with cabinets: if the panels are all rigidly glued together then at some critical frequency or other a note or notes in the music will trigger the cabinet's natural structural resonance. In such a rigid structure, there is nothing that can be done to suppress the ringing - and each time that note reappears, it tops up the ringing which then becomes a permanent drone underneath the music.
Conversely, in a thin-wall cabinet, the lossy joints (i.e. removable baffle/back and the generally 9-12mm thin panels used throughout the box) each act as an acoustic hairline crack. They inhibit the build-up of resonance. Simple as that really!"
If this is true then maybe I should build a mltl out of 12mm plywood. Then they should be relatively easy to move around and I could afford to make them quite large since they could be pushed back against a wall when not in use.
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Indeed. I have built any number of MLTL's out of 12mm Baltic birch with panels over a meter long and up to 30cm wide. I usually place longitudinal stringers on long unsupported areas, but I am not sure even that is required. I am currently building a pair for a show and one has the stringers and one does not. I am going to play with bracing and various damping schemes. I'll report back someday. Anyway, audible panel resonance is not an issue with 12mm BB in this size speaker.
Bob
Bob
I've never seen 8mm locally. 6mm is available, but that's pretty thin! My concern with using 6mm would be that the amount of material needed for bracing would make 12mm cheaper overall. BTW, I always double the top (24mm) because it makes a nice tick--tick sound when rapped with a knuckle. I think that 12mm is sufficient, though.
Bob
Bob