I think mine are doing 31Hz @ -3dB. I'll have to double check.
A pretty good estimate.
Baffle size, driver placement and mostly the crossover. I still would not do a 12" on OB - unless you are limited in baffle size. I've done it, and it can sound darn good (I still have the Peerless woofers) - but once you go to more cone area, you won't go back.The Maggie's do it from 48 x 19 inches . That is so close to being domestically acceptable .
31Hz - 3 db is superb .
Adastra UK were a company my old boss did business with ( back to 1949 ) . They seems to do impossibly good drivers at low prices . I hope to get the data sheets soon . 18 inch Qts 0.7 should work . One they do 902.430 is nice although small . Qts of 1.5 if I am correct ?
AVSL Group : Product : 902.430UK
31Hz - 3 db is superb .
Adastra UK were a company my old boss did business with ( back to 1949 ) . They seems to do impossibly good drivers at low prices . I hope to get the data sheets soon . 18 inch Qts 0.7 should work . One they do 902.430 is nice although small . Qts of 1.5 if I am correct ?
AVSL Group : Product : 902.430UK
This is your average cheap 15 inch speaker Qts 0.6 I think . The magnet is about like that of a KEF B110 . What you get is a lower resonant frequency than you might from a smaller speaker . Also the ability to move air when not doing any obvious movement . The sensitivity of 95dB / watt is useful . I have seen people say they add magnets to them for not very much money ($10 ) .The magnets just stick on without any glue . I have no idea if it works . The people writing seemed convinced .
If I were to use 2 x 12 inch per side I wonder if the line array problems set in if vertical ? Could even be useful . Generally I have not liked 2 x 12 inch used that way . Perhaps that is the reason ? As I might crossover at 900 Hz I doubt it matters . 2 x 12 is cheaper than 1 x 15 inch .
There is an analogy with the Lotus 7 car as seen in the series The Prisoner . The car is fast regardless of engine fitted . Even when side valve . A V8 somehow doesn't shine the way it should as it exceeds the envelope .
There is an analogy with the Lotus 7 car as seen in the series The Prisoner . The car is fast regardless of engine fitted . Even when side valve . A V8 somehow doesn't shine the way it should as it exceeds the envelope .
Why do you want to cross so high? Better to meet the woofer lower if you can. Although the higher point can work, with some work. What would you be crossing to?
Also remember that to get proper bass response you'll be trading away a lot of upper mid, sometimes 10dB or more - that's the sacrifice for no box. If you don't attenuate that rising response, you end up with a gutless sounding speaker, a fault of too many OBees.
What would you be crossing to?Also remember that to get proper bass response you'll be trading away a lot of upper mid, sometimes 10dB or more - that's the sacrifice for no box. If you don't attenuate that rising response, you end up with a gutless sounding speaker, a fault of too many OBees.
Why do you want to cross so high? Better to meet the woofer lower if you can. Although the higher point can work, with some work.
Also remember that to get proper bass response you'll be trading away a lot of upper mid, sometimes 10dB or more - that's the sacrifice for no box. If you don't attenuate that rising response, you end up with a gutless sounding speaker, a fault of too many OBees.
I lost sight - is this to be a 2 or 3 way setup?
If 2 way, then perhaps Nige HAS to use the woofers high enough for the tweeter to take over, in which case I doubt 900 HZ is high enough.
If 3 way, then Pano's question is more than valid. Perhaps we should take a hint from yesteryear models, say AR's 500/5,000 Hz.
Mine crosses over at 800 Hz, but this was dictated by the choice of the midrange driver. We (my friend and I) wanted it because we thought it was an outstanding unit, and no matter how we worked it, it didn't feel like going below 800 Hz without some unwanted side effects. Myself, I would have loved it taking over at 500 Hz or so.
But in all honesty, I can't complain on any other than psychological basis.
The suggestion was 900 Hz as a maximum , I read it somewhere . 250 hz a probable as the resonant frequency of the 3.5 inch " full range " units is 200 Hz . They seem to peak at 10 kHz . The idea is to ask them to do 7 kHz . As said previously I intend to use a PA crossover to nail my needs . I hope to model the active amplification to get a reasonable response .
This is the idea so far . More likely 15 inch as efficiency is better . Wood comes in 2400 mm , so 1200 is a preferred height . Is it just me . Is the Golden ratio as pleasing to the eye as everyone says . It looks a bit bloated ? 1200/ 1.618
If you like I am speculating again . What on Earth can we do if we don't ? I always build the things I talk about . That is when speculation moves to proof . I don't expect to beat the Maggie's . I expect it to be good on typical material . The Maggie's best trait is even handedness . The Quads do not have that . Colleen who these are for said if any good she will have the Maggie's , No way . She wants a scratch filter for vinyl . That will have to be digital ( yikes ) . I bought her a JVC direct drive . I have fallen for it . It is 1/4 decent and better than most CD . So easy to use . On Bellafonte it was hard to say anything wrong at all .
Mr Wayne has a point . 18 inch which is still cheap enough , is a baffle in it's own right . Love that photo .
I have a hunch using a 15 inch and having to move it further off centre is no bad thing ? Does the floor compensate for lack of baffle or the opposite ? One idea I had is to have a bolt on baffle if a lager house . It would go behind to give a step . Also a Boffle for party mode ( baffles like exhaust silencer ) .
This is the idea so far . More likely 15 inch as efficiency is better . Wood comes in 2400 mm , so 1200 is a preferred height . Is it just me . Is the Golden ratio as pleasing to the eye as everyone says . It looks a bit bloated ? 1200/ 1.618
If you like I am speculating again . What on Earth can we do if we don't ? I always build the things I talk about . That is when speculation moves to proof . I don't expect to beat the Maggie's . I expect it to be good on typical material . The Maggie's best trait is even handedness . The Quads do not have that . Colleen who these are for said if any good she will have the Maggie's , No way . She wants a scratch filter for vinyl . That will have to be digital ( yikes ) . I bought her a JVC direct drive . I have fallen for it . It is 1/4 decent and better than most CD . So easy to use . On Bellafonte it was hard to say anything wrong at all .
Mr Wayne has a point . 18 inch which is still cheap enough , is a baffle in it's own right . Love that photo .
I have a hunch using a 15 inch and having to move it further off centre is no bad thing ? Does the floor compensate for lack of baffle or the opposite ? One idea I had is to have a bolt on baffle if a lager house . It would go behind to give a step . Also a Boffle for party mode ( baffles like exhaust silencer ) .
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I currently use a Vifa 3.5" drive for everything above ~300Hz, which is where the acoustic crossover happens. See here: Vifa TC9FD
It actually has so much top end response that it needs a shelf filter to tame it. It can't keep up with the double 15s, but still sounds quite nice. No problem with the single 15"
I have quite an assortment of drivers to use in that position, both new and vintage, so it's fun to play around. All have their advantages and disadvantages.
My advice to you - if you want to build an OB - is "go simple". I built at least 3 OBs before I got something that sounded worth a damn, and I had help! Really, the first ones were awful. They just don't work like box speakers and it can take time to get that thru your head. It took 2 years to get it thru mine.
I say start with a 15 and a fullrange. Find a crossover that allows you to split the crossover frequencies and adjust the slopes, they will NOT be classic box slopes or points. AFAIK, only digital PA crossovers offer that possibility. So you may have to look elsewhere.
It actually has so much top end response that it needs a shelf filter to tame it. It can't keep up with the double 15s, but still sounds quite nice. No problem with the single 15"
I have quite an assortment of drivers to use in that position, both new and vintage, so it's fun to play around. All have their advantages and disadvantages.
My advice to you - if you want to build an OB - is "go simple". I built at least 3 OBs before I got something that sounded worth a damn, and I had help! Really, the first ones were awful.
They just don't work like box speakers and it can take time to get that thru your head. It took 2 years to get it thru mine.I say start with a 15 and a fullrange. Find a crossover that allows you to split the crossover frequencies and adjust the slopes, they will NOT be classic box slopes or points. AFAIK, only digital PA crossovers offer that possibility. So you may have to look elsewhere.
I've taken the plunge and bought the drivers above ( 15 inch , # 10064 ) at $80 the pair inc everything ( I would think $50 USA ) . I don't know the Qtc . I think that almost suits me best . Having looked at the others they do 0.7 seems correct . At first for the sake of knowing I will run them in open air . Although premature a bit of resistance added to see if it does things I expect . The version ordered 101 db / W . These are repair units for a ready made speaker and are a tad better than the general version ( 95 dB ) . No mid and no tweeters . Just them with whatever top and bottom they will take . After that whatever comes to hand .
The Vifa is very much like what I am looking at . The line array might be a mistake .
I suspect the Motorola clone horn will be OK . As someone said even notes that stop at 20 kHz ( CD ) appreciate the speed of a super tweeter . Lars of Nordost . He was saying we hear filtering even when a reduced bandwidth signal .
I notice people have the bass unit nearer the floor than centre . Any thoughts ?
The Vifa is very much like what I am looking at . The line array might be a mistake .
I suspect the Motorola clone horn will be OK . As someone said even notes that stop at 20 kHz ( CD ) appreciate the speed of a super tweeter . Lars of Nordost . He was saying we hear filtering even when a reduced bandwidth signal .
I notice people have the bass unit nearer the floor than centre . Any thoughts ?
OK, stick them on a baffle with no crossover and have a listen. My bet is that they'll work just fine, but you'll need a low pass filter to flatten their response to anything usable. Start looking at big inductors, in the 10mH-20mH range. That's what you'll need, and they may cost more than the woofers.
Yes, the line array is a mistake. My first OB was an old 12" and a Motorola horn. It wasn't easy to get them to sound right on OB. As a super tweeter, the horn is OK.
Yes, the line array is a mistake. My first OB was an old 12" and a Motorola horn. It wasn't easy to get them to sound right on OB. As a super tweeter, the horn is OK.
Arghhh , wasting time gents , OB tonal Misery ... Anyway the way it used to be and still is ....
When Albums Ruled the World BBC Full musical documentary movie 2013 - YouTube
Anyway the way it used to be and still is ....When Albums Ruled the World BBC Full musical documentary movie 2013 - YouTube
I had calculated about 30 mH so feel I must be seeing the picture correctly . The reason to try free air is to repeat how I came to this idea when trying an 8 inch Spendor unit . The Spendor had a reputation for low colouration , speed I would not say was it's best quality . Out of the box that changed , coloration less and speed dramatically better . On piano it even seemed to be realistic . On voice it lacked bass . A topsy turvey world where a bassy instrument the piano has plenty and the voice which seems not to need it suffers . I guess percussion can be mistaken for bass . Frank Sinatra on original vinyl is very good for assessing bass . The reissues seem not to have it . I have a hunch it will sound as if it has greater HF than is true . With 101 dB sensitivity EQ should be possible . Back to percussion . If a signal is fast enough maybe the bass message is preserved ?
They are the spare parts of these .
Skytec QTX Sound 15" active P.A - YouTube
Below is the BC1 data and the unit I will use . Fs of the Spendor is much lower .
Arghhh , wasting time gents , OB tonal Misery ...
When Albums Ruled the World BBC Full musical documentary movie 2013 - YouTube
It is hard to think I didn't make this program . ELP Tarkus ? Tubular Bells was made in the next village to where I live . At night I hear the trains in the night which come exactly from there . It is a very beautiful manor house .
A cheap inductor ? A reel of copper wire not called an inductor ? Why not ? Andrew T you must know ? EG 0.8 mm 500 g .
I rewound a vacuum cleaner once ( remember I do things like this , less so now ) . Watched TV and took 3 hours I guess . The wire was perhaps 0.8 mm and original 0.72 mm . No problems , more suction . Same number of turns . Best ever rewind was Honda 900 ( FA ) . The only bike I had without kick start had dodgy solenoids . Slightly thicker wire , as much as would fit in the bobbin solved the problem . I am told it was to prevent smarting if battery low . Alas with age they failed and were not cheap . A coin on the contacts worked , not nice as the current is high . Honda HT also no good . Apparently done as the crankshaft was fragile ( 107 BHP USA model ) . The coils required about 2 V more to give sparks at 8000 RPM . Some did that ( Bike Magazine racer ) .
http://en.wikipedia.org/wiki/The_Manor_Studio
I used to talk to the guys from Radiohead . I had no idea who they were . Their road manger ( she ) , her boyfriend was my hairdresser . He was gay so she decided to go on the road with this unknown band . Nice girl and wasted on him . Everyone was pointing it out to her . They seem about the last to record there .
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I have twice posted an excel electronics calculator for air cored coils, with other useful calcs in one of those postings.
Thanks Andrew , was sure you would know . It's got to be a cheap way of getting one ? If you have link that would help . At this moment I don't have a meter with inductance range . I guess a signal generator and resistor will say something ? Always seemed to tally within 20 % of stated values . 50 Hz via a transformer seems to work OK . Someone said build an LC oscillator . How hard is that ? 30 mH + 9R4 @ 50 Hz will be near to a question I will be asking .
My speaker ideas are getting close to this .
http://www.enjoythemusic.com/magazine/equipment/0606/visation_nobox_bb_loudspeaker.htm
My speaker ideas are getting close to this .
http://www.enjoythemusic.com/magazine/equipment/0606/visation_nobox_bb_loudspeaker.htm
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Running the 15 inch units in free air . As is totally useless . With 10 R series resistor there is a hint of excellence . Depth was non existent without it . Boom ? If only . Treble needs turning down ! Even has a hint of something one would call treble and very open ! Bass is full up on standard tone controls . For once in my life I need them . The shock is how little output considering . Plenty enough for my needs . From now it can only get better I feel . There is even bass , fast bass !
Wood is decided as Wicks our local builders merchant has 18 mm x 1220 x 606 on special . There will be 3.6 mm plywood at the front bonded with PVA .
No shout and good sibilance ! 10 R makes big difference .
Wood is decided as Wicks our local builders merchant has 18 mm x 1220 x 606 on special . There will be 3.6 mm plywood at the front bonded with PVA .
No shout and good sibilance ! 10 R makes big difference .
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