I see you got the 12lta.
Reading here, seems best bet is to cut off dust cap, add a phase plug, then add a supertweet crossed with a single cap (move it back and forth till sounds best).
post 99
http://www.diyaudio.com/forums/full-range/179161-beta-12lta-3cf-box-port-size-10.html
maybe place some cotton batten between whizzer and the cone.
Some prefer the lower qts eminence driver for open baffle, but they'll need more boosting than a floppy alpha 15.
Reading here, seems best bet is to cut off dust cap, add a phase plug, then add a supertweet crossed with a single cap (move it back and forth till sounds best).
post 99
http://www.diyaudio.com/forums/full-range/179161-beta-12lta-3cf-box-port-size-10.html
maybe place some cotton batten between whizzer and the cone.
Some prefer the lower qts eminence driver for open baffle, but they'll need more boosting than a floppy alpha 15.
I will start with just the 12 inch and see where it goes . People seem to place them 1/3 rd down and inwards so as stagger the frequencies of cancellation . There are calculators .
mh-audio.nl - Home
The 15 inch I have is a bit like the US market GRS unit and looks an Eminence clone . I like it's 1960's gathered edge . Should last a long time unlike the foam edge .
Cotton wool . Good idea .
Back to the original question . Do full range speakers need a crossover ? Theoretically no . In truth they need all the components we would call a crossover too give their best . The 12 LTa is about as good as it gets without a crossover in my guess ? If a box is OK good bass is possible . If a piezo horn was used it also would need no crossover . A simple capacitor and resistor could be called a protection device if wanting an excuse to call it other than crossover . In truth it is that ( 4 to 6 kHz protection frequency ) . BTW piezo's sound bad when asked to do 1.5 kHz , said to quack . At 4 to 6 K they have less work to do and sound almost like ribbons . Some cost $4 and are OK . I would suggest even Quad 63's would benefit from $4 horns from 10 kHz up . Rumour say they go to 30 kHz . I will try the paper cone versions soon as they look interesting . Never have seen them used . They look 1950's Altec .
Nigel
mh-audio.nl - Home
The 15 inch I have is a bit like the US market GRS unit and looks an Eminence clone . I like it's 1960's gathered edge . Should last a long time unlike the foam edge .
Cotton wool . Good idea .
Back to the original question . Do full range speakers need a crossover ? Theoretically no . In truth they need all the components we would call a crossover too give their best . The 12 LTa is about as good as it gets without a crossover in my guess ? If a box is OK good bass is possible . If a piezo horn was used it also would need no crossover . A simple capacitor and resistor could be called a protection device if wanting an excuse to call it other than crossover . In truth it is that ( 4 to 6 kHz protection frequency ) . BTW piezo's sound bad when asked to do 1.5 kHz , said to quack . At 4 to 6 K they have less work to do and sound almost like ribbons . Some cost $4 and are OK . I would suggest even Quad 63's would benefit from $4 horns from 10 kHz up . Rumour say they go to 30 kHz . I will try the paper cone versions soon as they look interesting . Never have seen them used . They look 1950's Altec .
Nigel
WIRES.CO.UK 0.750mm to 2.000mm Polyester Enamelled Copper Wire
Just received my cheap meter ( see item #8 ) . Pleased to say it works well . A 10.6 nF cap measured to 2% ( 10.78 ) and a 10uF also ( compared with my 0.5% accurate meter ) . Resistance better than 1% . Inductance tallied with known values . You have to push a button to go from R to L or C . It has no indication , have resistor handy to check which range is all it requires . Sensible soft case .
A 1/2 empty reel of 1 mm wire ( RS 357-788 ) is about 0R8 and 1.3 mH . 1R6 fully wound . The turns will not double , will be perhaps 1.85 ? I think if my maths is is right 5 mH is possible ( 5 mH is ratio 1.94 if 1 = 1.3 mH ) ? 1R6 is not out of the question if an open baffle design . 5 mH air-cored $15
a17 Inductance Calculator
http://www.parts-express.com/pe/showdetl.cfm?partnumber=255-284
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depends on what you use them for, for low volume listening nothing is needed, if you plan on cranking them then some prefer a zobel network to keep the impedance flat and takes a strain off the amp. Some full ranges tend to be strong in certain frequencies so you can design a bandpass to soften that peak.
Myself, I don't use anything, if the speaker doesn't sound good in a box that models well I will add a zobel network and if it still sounds like crap it becomes a "opps that didn't work out" and on to another project.
Myself, I don't use anything, if the speaker doesn't sound good in a box that models well I will add a zobel network and if it still sounds like crap it becomes a "opps that didn't work out" and on to another project.
The full range speaker is the prime component of open baffle designs . Inductors are often used to allow good bass and correct mid range . Before 1960 it was not unusual to use open baffle speakers . Stereo and a company called Acoustic Research changed that . Ever since then a way of thinking has developed that that makes open baffle and box speakers seem like opposites . It is wise to keep that idea in mind as often they are . Good practice of one is often bad practice of the other principle . I would also argue that Acoustic Research holding patents put others off of doing the best box speakers they could . Ironically AR almost used the tricks of OB to do their special magic . In much the same way Shure persuaded us we don't need MC pick-ups ( Ortofon MC patents ) the speaker world convinced us we don't need OB or AR . Shure is great and so are most speakers . The best ? I don't think so . Today we have speakers that are still hampered by 1960's problems . Namely a box you might lift is not as good as an open baffle ( 3 tons calculated mass to give similar low distortion , simplistic I know and arguably wrong , good someone tried to say ) . Like the Concorde and Boeing 747 it gets tricky to say one is better than the other as they are so different . In commercial terms the 747 is unquestionably better and that analogy holds true for speakers . Unlike that field of science the amateur can choose . A piece of 4 x 2 foot plywood is cheap . If it doesn't work out build the 747 instead . Like Concorde the baffle isn't easy . It is arguable that the baffle can be as good or better than any box speaker . The speaker in have in mind can be 30 Hz - 3dB . It will need an inductor or EQ'ed amp . It should sound like speakers costing more than most sensibly priced motorcars . It might cost $500 to build . The beauty of this idea is it is cheap ( $30-40 for a simple pair of baffles . 18 mm MDGF + 12 mm ply ) to find out espeically if the speaker drive units are usable either way , many are . The baffle will be rejected by many because it will take over your house . In my house that is OK .
Full range a good idea ? Perhaps not . However to add a tweeter one day is what might be done to improve a full range . Many like me will use a full range out of pride . A ribbon tweeter is how pride should be put to one side . My speakers are Magneplanars . Almost full range . The crossover is minimal . Very easy to live with .
Full range a good idea ? Perhaps not . However to add a tweeter one day is what might be done to improve a full range . Many like me will use a full range out of pride . A ribbon tweeter is how pride should be put to one side . My speakers are Magneplanars . Almost full range . The crossover is minimal . Very easy to live with .
The EQ components for a full range drive unit .
I looked up Qts for AR 3 . It was at one point about 0.9 . That would seem the ideal universal figure . The inductor was depending on model 4 mH with about 0R8 DC resistance ( DCR ) . A stab in the dark 16 AWG and 20 oz of copper .
http://www.diyaudio.com/forums/multi-way/88217-t-s-parameters-what-does-qts-have-do-dipole.html
watch for the honky or "cupped" sound perhaps caused by large whizzers.
I noticed it on the pioneer B20 and have seen comments of it on the 12lta.
Norman
I noticed it on the pioneer B20 and have seen comments of it on the 12lta.
Norman
I read years ago the only way a wizzer can work is by brake up modes , the main speaker is a piston by comparison . The speaker I am building might use a wizzer if it seems OK . I was advised not to say no without trying . 12LTa has a rising treble for nightclub vocals . It might be possible to stop it's prime function a little and have a nicer more linear output . 1g of cotton wool is better than any electrical EQ . The ribbon tweeter I have in mind will do 4.5 kHz up . If i can get 5 kHz from the wizzer the job is done . My adviser says the wizzer may be enough .
I am going to have a bash at the EQ amp for an additional 15 inch bass unit used on my baffle . If I have worthwhile data I will post .
I am going to have a bash at the EQ amp for an additional 15 inch bass unit used on my baffle . If I have worthwhile data I will post .
Pistonic operation in any wideband speaker is a bit of a myth TBH, since the substrate is carrying the HF signal. Another way of saying that wideband speakers produce the majority of the BW they cover via controlled resonance. Otherwise known as 'breakup' -the critical point of course being that there is resonance and there is resonance. Uncontrolled resonance = something to be avoided. Controlled resonance is another matter. Wideband speaker design is, amongst other things, about how well you create and control this. Same applies to many tweeters toward the top end of their BW for that matter.
Most (not all, but most) widebanders employ some form of mechanical XO, be it handing over to a whizzer cone or dust-cap, or progressive decoupling of the outer sections of the main cone etc. Personally, I don't like whizzer cones all that much since they have their own issues, some of which are noted above, but they can work reasonably.
Most (not all, but most) widebanders employ some form of mechanical XO, be it handing over to a whizzer cone or dust-cap, or progressive decoupling of the outer sections of the main cone etc. Personally, I don't like whizzer cones all that much since they have their own issues, some of which are noted above, but they can work reasonably.
Here is a study I am doing on an EQ amp for an open baffle speaker . The amp is not bad as a general purpose design ( use 16.5 pF = 15 pF , 47 K ) . It is made from parts I have . The output of for example 2V rms 20 Hz is 100 mV rms at 1.39 kHz or - 26 dB . As the amp is unity gain stable when using 125 pF VAS compensation , anything you like is possible . If the 47K is made zero ohms it is happy to work .
The distortion is at 3 watts because the output is reduced and my signal generator is at it's limit . The amp is no more distorted at 60 watts . It has about 0.!5% second harmonic at 22 kHz .
Well, long time since the last reply...
So back to the subject: if I want to filter a full range how do I proceed? Is there a software to measure filters for full range drivers. I've got a pair of small full rage drivers and would like to avoid very low frequencies that are impossible to come out from 3" full range. Also the mids so it doesn't come too forward. Thanks and happy new year 2015.
So back to the subject: if I want to filter a full range how do I proceed? Is there a software to measure filters for full range drivers. I've got a pair of small full rage drivers and would like to avoid very low frequencies that are impossible to come out from 3" full range. Also the mids so it doesn't come too forward. Thanks and happy new year 2015.
For the high pass filter you can get an approximation from a table like this. (simple filter, shallow slope).
6 db Crossover Table
or for a steeper slope (more power handling of the driver, but more components)
12 db Crossover Table
for a notch filter, that is to say to remove the part of the midrange, you can use this:
Parallel Notch Fliter Designer / Calculator
6 db Crossover Table
or for a steeper slope (more power handling of the driver, but more components)
12 db Crossover Table
for a notch filter, that is to say to remove the part of the midrange, you can use this:
Parallel Notch Fliter Designer / Calculator
I have never used crossovers in any of my speaker designs.
However most are full range drivers anyway.
I do run a sub from a full range signal and it sounds OK.
I use Fane Sovereign speakers 12-200LT and 12-250TC.
Both are good full range speakers.
However most are full range drivers anyway.
I do run a sub from a full range signal and it sounds OK.
I use Fane Sovereign speakers 12-200LT and 12-250TC.
Both are good full range speakers.
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I use Eminence 12 Lta. I agree with the other Nigel ( 4 x 2 foot baffle ). I use + 16 dB 30 Hz EQ. The treble is very like the Magneplanar SMGa I own in quantity. I have some Dynaco A25 that are similar. Spendor BC1's on loan. The Spendor will go to 25 kHz and above if free air. The difference isn't worth loosing sleep over. Spendor themselves would have not bothered with the supertweeter except no BBC orders if so. The supertweeter was for hearing 625 x 50 Hz TV line buzz ( 525 x 60 in USA ? ). The 12 Lta never makes me think the SMGa is better. The Dynaco is worse although wonderful. The Spendor sounds very much like a baffle speaker. Sometimes the box is heard which is very disconcerting. I have tried a BC1 in free air. It was this test that convinced me to go OB. The BC1 driver would never take the EQ. The 12 Lta is designed for 500 watts peak. Mostly I use 1 watt with 10 watts peak. It is loud enough to cause hearing damage above that. Strangely OB speakers do not sound like box speakers either EQ'ed or not. It just sounds very good. Nothing like a ported speaker. I guess as bass is less phase critical this major defect is hidden. With digital EQ even that need not be so. Overal I like 12 Lta best. Perhaps as on paper it looks a non starter. If anyone else showed me them I guess I would be more critical if shop bought.
Happy new year.
First you would need to measure the driver response in order to see what might need correction. REW is such a software and it's free:
REW - Room EQ Wizard Room Acoustics Software
There are numerous cheap devices that can do equalization. One example would be Home | miniDSP
I think the better advice is to get a drive unit that can work. Plenty of advice on that is available. The full range I use is starting to roll at 12 kHz. As I already give it plenty of bass EQ why not build a 12 kHz boost control. More useful a 75 us control in the RIAA as it will adjust recordings also. When I looked at this I tried a piezo horn top. It is a cheap way to see if something is needed. My friend has some firing backwards against a wall with expensive Fostex drivers. It works very well. He didn't need a crossover. If front mounted I would use one as it helps the cheap tweeter work. For me 14 kHz seems about right. In some ways these devices used for PA are better than many posh tweeters.
Looking at the maths of my set up. Driver 99 dB/W. EQ 16 dB at 30 Hz. Lets say I choose a ribbon tweeter to feed in at 14 kHz and accept the ripple it causes. Said to be less important if > 7 kHz. There is an oppertunity for a SE valve amplifer with ideal coupling. The transformer designed for lests say >1 kHz. It might use a switchmode core. The amp might only be 2 watts. 2 x EL84 ? The gain of that amp to suit the tweeter.
If I didn't choose this route I think I would try a Tannoy driver. My own 12Lta with a coaxial tweeter might work.
Looking at the maths of my set up. Driver 99 dB/W. EQ 16 dB at 30 Hz. Lets say I choose a ribbon tweeter to feed in at 14 kHz and accept the ripple it causes. Said to be less important if > 7 kHz. There is an oppertunity for a SE valve amplifer with ideal coupling. The transformer designed for lests say >1 kHz. It might use a switchmode core. The amp might only be 2 watts. 2 x EL84 ? The gain of that amp to suit the tweeter.
If I didn't choose this route I think I would try a Tannoy driver. My own 12Lta with a coaxial tweeter might work.
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