Hello all readers. This is my first post here.
I'm a French guy who is living in Japan, and one month ago, a customer give me a pair of big speakers :
They are selfmade (by who ?) replica of the Altec-Lansing A5/A7 but more little (about half of the volume)
The tweteers are in top a Pioneer PD50/PH50 who were not connected and the big horns are Altec-Lansing 908-8A/511B who were connected.
I don't have any clue with them. I'm now using the Pioneer only as I find them far better than the Altec.
There is a JBL N1200 (1200Hz) crossover.
The problem I have is with the big low-frequency speaker.
This is a 38cm (15inches) made by a Japanese manufacturer RAMSA (National/Panasonic) WU-S906-8 :
I've managed to retrieve the Thiele/Small parameters and I found :
Fs : 27Hz (manufacturer give 21Hz)
Vas : 311 liters
Qms : 1.34
Qes : 0.31
Qts : 0.25
The box :
~160 liters, with a big port (a simple hole in the front frame) 50cm x 10cm.
I'm using SynRTA for retrieving the response curves (with a unknown mic, but I could compare measures between them).
Here the response of the original design :
In yellow the speaker from 1cm.
In green in front of the (big) port.
In red overall response from some distance (don't remember).
The box resonance frequency is ~55Hz.
After reading a lot about ported speakers, I've managed to modify the port.
First try : 2 ports diameter 10cm; 40cm long :
In red the free-air response of the speaker (out of the box).
In green at 1cm speaker in the box.
The box resonance is now at ~25Hz. It seems there is a little more basses, but this is not enough.
Second try : 2 ports diameter 10cm; one 40cm long, the other 60cm long :
In red the speaker from 1cm.
In green the longest port.
In yellow the shortest port.
In grey the overall at 1m (vertically shifted).
The box frequency is now at ~20Hz, but it lack basses again.
When I saw the grey curve, I wonder why there is a big loss under 200Hz.
And this is my question : why I loose a lot of basses when I put the mic farther ?
Here a simple measure with the mic at 1cm and 50cm :
There are 8dB less at 600Hz, but 24dB less at 100Hz. Why ?
I could understand that the low frequencies are less directives and the power go away in all direction compare to highest frequencies, but it should be linear, and here there is a big gap from 200Hz and under.
I've made a test withe another speaker (a 38cm car sub-woofer) in free-air and in a little box (40 liters) :
Red & green are free-air.
Yellow & grey are in the box.
So the box change the "losses" in the low frequencies, but once again, the losses are not linear.
Why ? And how could I have the better basses possibles without adding a Sub-woofer (I'm now using a poor Sony Sub, and it work very well compare with or without). But it's terrible to have a BIG 38cm in a BIG box who don't do basses compare to a poor 10cm (I don't know exactly, but the sub is not big) in a poor box.
Sorry for the so looonnng post and for my English !
Thanks in advance !
Cheers,
Christophe.
I'm a French guy who is living in Japan, and one month ago, a customer give me a pair of big speakers :
An externally hosted image should be here but it was not working when we last tested it.
They are selfmade (by who ?) replica of the Altec-Lansing A5/A7 but more little (about half of the volume)
The tweteers are in top a Pioneer PD50/PH50 who were not connected and the big horns are Altec-Lansing 908-8A/511B who were connected.
I don't have any clue with them. I'm now using the Pioneer only as I find them far better than the Altec.
There is a JBL N1200 (1200Hz) crossover.
The problem I have is with the big low-frequency speaker.
This is a 38cm (15inches) made by a Japanese manufacturer RAMSA (National/Panasonic) WU-S906-8 :
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I've managed to retrieve the Thiele/Small parameters and I found :
Fs : 27Hz (manufacturer give 21Hz)
Vas : 311 liters
Qms : 1.34
Qes : 0.31
Qts : 0.25
The box :
~160 liters, with a big port (a simple hole in the front frame) 50cm x 10cm.
I'm using SynRTA for retrieving the response curves (with a unknown mic, but I could compare measures between them).
Here the response of the original design :
An externally hosted image should be here but it was not working when we last tested it.
In yellow the speaker from 1cm.
In green in front of the (big) port.
In red overall response from some distance (don't remember).
The box resonance frequency is ~55Hz.
After reading a lot about ported speakers, I've managed to modify the port.
First try : 2 ports diameter 10cm; 40cm long :
An externally hosted image should be here but it was not working when we last tested it.
In red the free-air response of the speaker (out of the box).
In green at 1cm speaker in the box.
The box resonance is now at ~25Hz. It seems there is a little more basses, but this is not enough.
Second try : 2 ports diameter 10cm; one 40cm long, the other 60cm long :
An externally hosted image should be here but it was not working when we last tested it.
In red the speaker from 1cm.
In green the longest port.
In yellow the shortest port.
In grey the overall at 1m (vertically shifted).
The box frequency is now at ~20Hz, but it lack basses again.
When I saw the grey curve, I wonder why there is a big loss under 200Hz.
And this is my question : why I loose a lot of basses when I put the mic farther ?
Here a simple measure with the mic at 1cm and 50cm :
An externally hosted image should be here but it was not working when we last tested it.
There are 8dB less at 600Hz, but 24dB less at 100Hz. Why ?
I could understand that the low frequencies are less directives and the power go away in all direction compare to highest frequencies, but it should be linear, and here there is a big gap from 200Hz and under.
I've made a test withe another speaker (a 38cm car sub-woofer) in free-air and in a little box (40 liters) :
An externally hosted image should be here but it was not working when we last tested it.
Red & green are free-air.
Yellow & grey are in the box.
So the box change the "losses" in the low frequencies, but once again, the losses are not linear.
Why ? And how could I have the better basses possibles without adding a Sub-woofer (I'm now using a poor Sony Sub, and it work very well compare with or without). But it's terrible to have a BIG 38cm in a BIG box who don't do basses compare to a poor 10cm (I don't know exactly, but the sub is not big) in a poor box.
Sorry for the so looonnng post and for my English !
Thanks in advance !
Cheers,
Christophe.
Hello and thanks to richie00boy & PeteMcK !
I have read your comments, and was thinking of them until yesterday.....
But why should I tune the box more higher ?.....
I believe I've been wrong from the beginning :
I've read on the Wikipedia page about the ported enclosures than the port acoustic pressure is added to the direct speaker acoustic pressure between the resonance of the driver & the resonance of the box if the resonance of the box is lower than the driver one, and subtracted if the box resonance is higher than the driver one.
That's entirely my fault.
That what I through (understand) and that was what it seems to me when I have been looking at the first curve (the original). (In fact that's what I through before I read).
That's why I'm trying to lower the box resonance frequency.
I've discovered the program WinISD who is pretty useful to "imagine" what should be the result.
In green the original ~57Hz
In pink the actual ~20Hz
In grey 42Hz
In blue 38Hz
In yellow 35Hz
Which one should I choose ?
jplesset, I believe you were lucky guy !
I have read your comments, and was thinking of them until yesterday.....
But why should I tune the box more higher ?.....
I believe I've been wrong from the beginning :
I've read on the Wikipedia page about the ported enclosures than the port acoustic pressure is added to the direct speaker acoustic pressure between the resonance of the driver & the resonance of the box if the resonance of the box is lower than the driver one, and subtracted if the box resonance is higher than the driver one.
That's entirely my fault.That what I through (understand) and that was what it seems to me when I have been looking at the first curve (the original). (In fact that's what I through before I read).
That's why I'm trying to lower the box resonance frequency.
I've discovered the program WinISD who is pretty useful to "imagine" what should be the result.
An externally hosted image should be here but it was not working when we last tested it.
In green the original ~57Hz
In pink the actual ~20Hz
In grey 42Hz
In blue 38Hz
In yellow 35Hz
Which one should I choose ?
jplesset, I believe you were lucky guy !
Greets!
OK, first things first, a little history……… the original was designed to be driven with a ~matching impedance amp [this nearly doubles a driver’s Qts] that had both bass and treble tone controls to flatten it out from ~75 – 11 kHz, the cinema soundtrack limits at the time, hence the relatively high tuning [Fb]. Its XO used an auto-former and impedance compensation.
Unfortunately, when driven with a low output impedance system and no EQ or impedance compensation its frequency response is truly appalling to most folk’s ears. Factor in a XO and [mid]woofer with a high frequency response not ‘voiced’ for it as yours is and it’s only good for fueling a weenie roast or BBQ cookout IMNSHO.
With that in mind, today one normally tunes it to whatever the lowest frequency the speakers are likely to ‘feel’ and then the rest of its response is ‘shelved’ down using one or more forms of acoustic and/or electrical EQ till it’s tonally flat in-room from whatever LF and HF corner frequencies one desires and only needs a sub system for either room EQ ‘fill’ in the woofer BW and/or only to handle the [infra]bass below the main’s tuning.
Typically, this is usually from the [mid]woofer’s Fs to ~32 Hz range and at least 15 kHz [assuming a 1” exit horn driver] with efficiency dropping to the low 90s as the trade-off. Not many 'free lunches’ in audio/speaker design.
Considering the woofer’s HF response, seems like a lower XO point around 650-800 Hz might help a lot if high power isn’t required of it since the 908 is optimized for >1 kHz on an 811 IIRC.
Adding baffle ‘wings’ on either or both sides is beneficial as is damping the HF horn’s ‘bells’ and around their mouth perimeters to reduce the strong reflections back to the throats that these truncated terminations plus vane ‘diverters’ create to comb filter [‘chop up’] its HF response.
Otherwise, how one broadband shelves down such a wide BW is so personal a sonic preference and room, signal chain dependent that I’ll leave it to you to decide what’s the best way overall to accomplish it. For my money, the pioneers got it right the first time, but today it’s a costly one.
One man's 'journey': Altec
Feel free of course to ask specific questions about whatever along the way though. Once dialed in, very few have been disappointed and then it’s normally because of the sectoral HF horn, not the cab’s lack of bass nor the big mid horn’s response. Indeed, it’s the latter that they mainly keep them for!
GM
OK, first things first, a little history……… the original was designed to be driven with a ~matching impedance amp [this nearly doubles a driver’s Qts] that had both bass and treble tone controls to flatten it out from ~75 – 11 kHz, the cinema soundtrack limits at the time, hence the relatively high tuning [Fb]. Its XO used an auto-former and impedance compensation.
Unfortunately, when driven with a low output impedance system and no EQ or impedance compensation its frequency response is truly appalling to most folk’s ears. Factor in a XO and [mid]woofer with a high frequency response not ‘voiced’ for it as yours is and it’s only good for fueling a weenie roast or BBQ cookout IMNSHO.
With that in mind, today one normally tunes it to whatever the lowest frequency the speakers are likely to ‘feel’ and then the rest of its response is ‘shelved’ down using one or more forms of acoustic and/or electrical EQ till it’s tonally flat in-room from whatever LF and HF corner frequencies one desires and only needs a sub system for either room EQ ‘fill’ in the woofer BW and/or only to handle the [infra]bass below the main’s tuning.
Typically, this is usually from the [mid]woofer’s Fs to ~32 Hz range and at least 15 kHz [assuming a 1” exit horn driver] with efficiency dropping to the low 90s as the trade-off. Not many 'free lunches’ in audio/speaker design.
Considering the woofer’s HF response, seems like a lower XO point around 650-800 Hz might help a lot if high power isn’t required of it since the 908 is optimized for >1 kHz on an 811 IIRC.
Adding baffle ‘wings’ on either or both sides is beneficial as is damping the HF horn’s ‘bells’ and around their mouth perimeters to reduce the strong reflections back to the throats that these truncated terminations plus vane ‘diverters’ create to comb filter [‘chop up’] its HF response.
Otherwise, how one broadband shelves down such a wide BW is so personal a sonic preference and room, signal chain dependent that I’ll leave it to you to decide what’s the best way overall to accomplish it. For my money, the pioneers got it right the first time, but today it’s a costly one.
One man's 'journey': Altec
Feel free of course to ask specific questions about whatever along the way though. Once dialed in, very few have been disappointed and then it’s normally because of the sectoral HF horn, not the cab’s lack of bass nor the big mid horn’s response. Indeed, it’s the latter that they mainly keep them for!
GM
Salut ZeTof
I have modified a few Altec A7/A5, the first time almost 30 years ago in Paris. They can sound fantastic, if done right. Stock they have a lot of problems.
First, of course, you don't have the real thing. But that should be OK. I'm sure you can get more bass out of them. As GM mentioned, they were designed to be driven by tube amps with a somewhat high output impedance. If using solid state amps, you may need to add a little series resistance.
Second, you will need to work on the ports for better basss. The stock ports of the Altec don't allow for low bass so they need to be reduced in area. Since your cabinet is smaller and your driver a bit different, perhaps you will need to cut some plywood or heavy cardboard to experiment with port sizes. GM and I can help there.
Third. It's good that you have measurements. That will help enormously for you to find the right direction and what works well. I like to use HOLMImpulse software (free!) but what you have should work just fine.
Forth. The crossover between the 15" and the horn is critical to getting the right sound. I do not like the stock Altec crossover and getting a generic crossover off the shelf is going to be difficult. In your case it probably needs to be custom.
I have modified a few Altec A7/A5, the first time almost 30 years ago in Paris. They can sound fantastic, if done right. Stock they have a lot of problems.
First, of course, you don't have the real thing. But that should be OK. I'm sure you can get more bass out of them. As GM mentioned, they were designed to be driven by tube amps with a somewhat high output impedance. If using solid state amps, you may need to add a little series resistance.
Second, you will need to work on the ports for better basss. The stock ports of the Altec don't allow for low bass so they need to be reduced in area. Since your cabinet is smaller and your driver a bit different, perhaps you will need to cut some plywood or heavy cardboard to experiment with port sizes. GM and I can help there.
Third. It's good that you have measurements. That will help enormously for you to find the right direction and what works well. I like to use HOLMImpulse software (free!) but what you have should work just fine.
Forth. The crossover between the 15" and the horn is critical to getting the right sound. I do not like the stock Altec crossover and getting a generic crossover off the shelf is going to be difficult. In your case it probably needs to be custom.
Hello and thanks Mr GM & Pano .
_______________________________
_______________________________
I'm using the Pioneer horns who have a sensibility of 103.5dB 1w/1m (almost flat from ~600Hz to 20kHz)
While the 15" woofer sens is 99dB.
But calculating (and making) of a new XO seems difficult to me for now.
What XO frequency do you suggest ? about 800Hz ?
_______________________________
And finally, I must say that my room is far from the "perfect" room. I have a lot of things inside, a lot of plant (I like plants !) and her size is ~5m width; ~12m long; and there is a triangular roof (directly under the outside roof, I don't know how to said in English) of about 3m of height in the center.
But I have to live with that !
Anyway, thanks again for all your suggestions !!
Best regards,
Christophe.
._______________________________
GM said:
By the way I'm driving them with a little Chinese tube amplifier of about 6-8W (this one).Pano said:
_______________________________
Pano said:
The JBL N1200 XO has an attenuator switch (0;-3dB;-6dB) I'm now in -6dB, and it seems to me that this is again a little too high. But when I look at the woofer response curve I have now, maybe it's normal !GM said:
I'm using the Pioneer horns who have a sensibility of 103.5dB 1w/1m (almost flat from ~600Hz to 20kHz)
An externally hosted image should be here but it was not working when we last tested it.
While the 15" woofer sens is 99dB.
But calculating (and making) of a new XO seems difficult to me for now.
What XO frequency do you suggest ? about 800Hz ?
_______________________________
I will do that. I've read here (good paper I think) that we can also use wool felt :GM said:
_______________________________
And finally, I must say that my room is far from the "perfect" room. I have a lot of things inside, a lot of plant (I like plants !) and her size is ~5m width; ~12m long; and there is a triangular roof (directly under the outside roof, I don't know how to said in English) of about 3m of height in the center.
But I have to live with that !
Anyway, thanks again for all your suggestions !!
Best regards,
Christophe.
a few points that have been mentioned in other threads on the A7...
...it is well worth doing a search here for those and reading through.
The front horn on the 15" driver causes a major tip up in the response. This is in addition to the natural tendency of these drivers to rise in response above the true bass region.
So, you end up with a significant rise in response from say just below 200Hz to where the horn meets it. This does have the "benefit" of providing a better SPL match at the xover point to the horn - the horn needs less padding. This gives the apparent reference sensitivity a higher number, which looks good on paper although not so good in reality.
Another point is that I am personally a negative fan of those metal cast diffraction horns. But if you have to use them the larger one is more better imo.
There is no point in the smaller one on top. I'd switch to something that actually works above say 5-7kHz. That would be far shorter and while it might use the same compression driver (what are you using?), it would be not that horn!
Imo, there is some question as to whether or not this style of front loaded bin has much value in home use other than the idea that it provides a neat way to get the acoustic centers of the 15" driver in line with the compression driver. But you fight with the rise from the front loaded horn on the bass driver. Maybe not a good trade?
Those metal horns absolutely need to be damped and prevented from ringing, if they are not already treated do it. But I'd try for other horns, even home made (many shown on this site).
Looking at the original post, it seems that the port freq was ~60Hz. Unfortunately, this is likely about right for an enclosure that is too small to permit the driver to go as low as you would like.
Then looking at ur simulated responses, the 60Hz response with the bump is actually a good one, since the combined acoustical response will reflect the rising response of the driver PLUS the front loaded horn.
Of course with this alignment, no low bass. But, flatter, but not really flat response at all.
What is the solution? There isn't one. The design has inherent characteristics that can not be directly overcome.
IF you put in a driver that will tune LOW, and you can find a way to cope with the rising response due to the driver + front loaded horn, you might get a flat-ish result. BUT the trade-off is that a driver that will go low in that volume will certainly also have lower sensitivity. That will mean that the power needed to equal the SPL of the horn will be greater. Out goes the idea of using a single full range low-ish power tube amp. In comes the high power amp, which likely ends up being solid state. Now you have a biamp system.
That's a clue - you can do more to correct the response if you go biamped. It opens the door to all sorts of things, including one of the many DSP based EQs, some of which are inexpensive, and maybe used only on the bass will have nil effect on the overall sound, except to make the system sound better.
When I did up an actual A7 for a client, we changed out the Altec driver and went with another prosound driver (an expensive one though) that would tune down to a true ~40Hz in the A7 box, AND i opted for a trick brickwall passive implementation of the Low Pass filter to get the effect of the front loaded horn down to ~3dB at the xover point. The xover point was moved to ~250Hz by using some mid/high horns that actually worked down to ~250Hz and covered high enough. Altec 1003 horns are an example that would work, although I used a different horn. Of course then you need a compression driver that will do the job down there too... this was biamped with a high power amp on the bottom end so that the peak output capabilities matched well between the highs and lows.
So, no easy path to be found!
PS. those horns in the pix were Altec 803, which were used for preliminary testing of the LP xover...
...it is well worth doing a search here for those and reading through.
The front horn on the 15" driver causes a major tip up in the response. This is in addition to the natural tendency of these drivers to rise in response above the true bass region.
So, you end up with a significant rise in response from say just below 200Hz to where the horn meets it. This does have the "benefit" of providing a better SPL match at the xover point to the horn - the horn needs less padding. This gives the apparent reference sensitivity a higher number, which looks good on paper although not so good in reality.
Another point is that I am personally a negative fan of those metal cast diffraction horns. But if you have to use them the larger one is more better imo.
There is no point in the smaller one on top. I'd switch to something that actually works above say 5-7kHz. That would be far shorter and while it might use the same compression driver (what are you using?), it would be not that horn!
Imo, there is some question as to whether or not this style of front loaded bin has much value in home use other than the idea that it provides a neat way to get the acoustic centers of the 15" driver in line with the compression driver. But you fight with the rise from the front loaded horn on the bass driver. Maybe not a good trade?
Those metal horns absolutely need to be damped and prevented from ringing, if they are not already treated do it. But I'd try for other horns, even home made (many shown on this site).
Looking at the original post, it seems that the port freq was ~60Hz. Unfortunately, this is likely about right for an enclosure that is too small to permit the driver to go as low as you would like.
Then looking at ur simulated responses, the 60Hz response with the bump is actually a good one, since the combined acoustical response will reflect the rising response of the driver PLUS the front loaded horn.
Of course with this alignment, no low bass. But, flatter, but not really flat response at all.
What is the solution? There isn't one. The design has inherent characteristics that can not be directly overcome.
IF you put in a driver that will tune LOW, and you can find a way to cope with the rising response due to the driver + front loaded horn, you might get a flat-ish result. BUT the trade-off is that a driver that will go low in that volume will certainly also have lower sensitivity. That will mean that the power needed to equal the SPL of the horn will be greater. Out goes the idea of using a single full range low-ish power tube amp. In comes the high power amp, which likely ends up being solid state. Now you have a biamp system.
That's a clue - you can do more to correct the response if you go biamped. It opens the door to all sorts of things, including one of the many DSP based EQs, some of which are inexpensive, and maybe used only on the bass will have nil effect on the overall sound, except to make the system sound better.
When I did up an actual A7 for a client, we changed out the Altec driver and went with another prosound driver (an expensive one though) that would tune down to a true ~40Hz in the A7 box, AND i opted for a trick brickwall passive implementation of the Low Pass filter to get the effect of the front loaded horn down to ~3dB at the xover point. The xover point was moved to ~250Hz by using some mid/high horns that actually worked down to ~250Hz and covered high enough. Altec 1003 horns are an example that would work, although I used a different horn. Of course then you need a compression driver that will do the job down there too... this was biamped with a high power amp on the bottom end so that the peak output capabilities matched well between the highs and lows.
So, no easy path to be found!
PS. those horns in the pix were Altec 803, which were used for preliminary testing of the LP xover...
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Ok guys.
I've made what you suggested about the tune frequency of the box.
That's a great improvement !
Happy that the physics laws are rights.
Who said low Qts driver will not give bass ?
In fact I'm very impressioned how the tuning of the box affect the bass output, I can't believe my hears ! This was at origin too high, I've made it too low, and with your help I'm very happy.
I've measured the response of the tweeter, and it's a little too high (about 3-6dB) again.
What software did you recommend for calculating XO and at what frequency do you suggest I should XO ? (I should have something as -12dB at the tweeter).
I really not have regrets to have begun this tread !
Thanks a lot !
Regards,
Christophe.
I've made what you suggested about the tune frequency of the box.
That's a great improvement !
Happy that the physics laws are rights
.Who said low Qts driver will not give bass ?
In fact I'm very impressioned how the tuning of the box affect the bass output, I can't believe my hears ! This was at origin too high, I've made it too low, and with your help I'm very happy
.I've measured the response of the tweeter, and it's a little too high (about 3-6dB) again.
What software did you recommend for calculating XO and at what frequency do you suggest I should XO ? (I should have something as -12dB at the tweeter).
I really not have regrets to have begun this tread !
Thanks a lot !
Regards,
Christophe.
Don´t forget the original design goal for this enclosure.
It was meant for typical cinemas/movie theaters in the 40´s.
Besides a few carefully built somewhat similar to classic (live performance) theaters with proper acoustics, most were just *long* rectangular mortar and brick "shoeboxes" with horrible acoustics.
People beyond 15/20 meters from behind screen speakers had a big intelligibility problem with way too reverberant audio, so A7 was designed in an schizo way to provide good sound with a relatively small cabinet: a very short horn, coupling and *focusing* sound above 200Hz so it reached farther into the audience, an even more focused horn above 500/800 Hz to improve voice intelligibility, a "presence peak" between 5/7 KHz didnt hurt that at all, and below 200Hz weakening response would be masked by room reflections and resonance.
A brilliant and very successful compromise design, at a price most movie theaters could afford.
Now all those characteristics make it a horrible *home* design ... unless your living room is a subway station or an indoors basketball court.
FWIW Altec also made home audio cabinets with similar speaker components, but in a more home friendly configuration.
It was meant for typical cinemas/movie theaters in the 40´s.
Besides a few carefully built somewhat similar to classic (live performance) theaters with proper acoustics, most were just *long* rectangular mortar and brick "shoeboxes" with horrible acoustics.
People beyond 15/20 meters from behind screen speakers had a big intelligibility problem with way too reverberant audio, so A7 was designed in an schizo way to provide good sound with a relatively small cabinet: a very short horn, coupling and *focusing* sound above 200Hz so it reached farther into the audience, an even more focused horn above 500/800 Hz to improve voice intelligibility, a "presence peak" between 5/7 KHz didnt hurt that at all, and below 200Hz weakening response would be masked by room reflections and resonance.
A brilliant and very successful compromise design, at a price most movie theaters could afford.
Now all those characteristics make it a horrible *home* design ... unless your living room is a subway station or an indoors basketball court.
FWIW Altec also made home audio cabinets with similar speaker components, but in a more home friendly configuration.
Christophe, that's good news! Happy to hear that you have gotten good results with the retune. That was fast. 
With my rig in the room corners, the low end has to be turned down below 60Hz or there is just too much of it. Of course the ports are closed down from the original large ports.
From your published plot of the Pioneer horn, I can see why you like it. It should be fairly easy to integrate with the 15" woofer. I'd target a crossover about 1 octave above where it rolls off. For example: The Altec 800Hz horn works well in the Valencia crossed at 1600Hz. It can play lower, of course, but sounds very good at that point.
If you can use a software that shows distortion on the sweep tone, that can be useful in finding a good crossover point.
With my rig in the room corners, the low end has to be turned down below 60Hz or there is just too much of it. Of course the ports are closed down from the original large ports.
From your published plot of the Pioneer horn, I can see why you like it. It should be fairly easy to integrate with the 15" woofer. I'd target a crossover about 1 octave above where it rolls off. For example: The Altec 800Hz horn works well in the Valencia crossed at 1600Hz. It can play lower, of course, but sounds very good at that point.
If you can use a software that shows distortion on the sweep tone, that can be useful in finding a good crossover point.
In the 3rd plot [and others], he shows the free air and in-box response and in the 4th plot, the grey shows the whole speaker where it's pretty plain that the 511 needs a much lower XO point unless significant frequency response shaping EQ is used and as you already know from experience it ideally needs a ~350 Hz horn/500 Hz XO point for HIFI apps.
GM
GM
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OK, now that I've cleared my eyes, I can see it.
Looks like a typical 15". Not as good on the top as an Altec 15", or course. It seems to peak at - what? - 1.6K? Also a hump at 600Hz. A least according to the factory plot and the free air plot. The in-box plot appears to be low passed.
Maybe try the cross 3rd order right before the woofer peak? Might still need a notch. The smaller horn may not make it down to meet the woofer, but I think it's worth a try because otherwise it looks so good. The 511 will need more work.
ZeTof -- Do you have any way to do an active crossover? Even just temporarily?
Looks like a typical 15". Not as good on the top as an Altec 15", or course. It seems to peak at - what? - 1.6K? Also a hump at 600Hz. A least according to the factory plot and the free air plot. The in-box plot appears to be low passed.
Maybe try the cross 3rd order right before the woofer peak? Might still need a notch. The smaller horn may not make it down to meet the woofer, but I think it's worth a try because otherwise it looks so good. The 511 will need more work.
ZeTof -- Do you have any way to do an active crossover? Even just temporarily?
Hello
I've listened about 10h now and I'm very happy at least there are bass now and I really believed that was not possible before asking here. So once again thanks a lot !!
I've just (for now and for test purpose) put a 9.1 ohms resistor in series with the tweeter after plotting the curve response at around the XO freq. (And I'm still at -6dB on the XO).
Now my XO is like this :
It seem that the real XO freq. is about 1050-1100 Hz as I've plotted the curve with and without reversing the polarity of the tweeter, and when inverted, there is a big gap at around this frequency.
Once again, I really don't thinking about using the Altec/lansing 908-8A and 511 as since my first try the Pioneer sound very better, and after looked at the spec. that seem to be normal.
I own an little graphic equalizer, but only 7 bands (60,150,400,1k,2.4k,6k,15k).
For what purpose did you ask ?
I'd read the thread about the XO (2 firsts page for now, for understand how that works) :
My 15" have a cone breakup at ~1.6kHz and my Tweeter could go at 800Hz, but this is just after it's cutoff (500-600Hz) so not 1 octave beyond.
Anyway in it's spec. they said XO "800Hz or more".
But is the result would be really worth ?
I'd been made curves with HOLMImpulse, here the results from ~1m in front of the speaker (~in the axix of 15"). But as I don't know how interpret this curves (apart the response), I don't know what that mean (or is it good or not).
I'd not yet damped the tweeter (nor mechanically as GM recommend, nor electronically as my 9.1 ohms resistor lower the damping I believe) :
Here are measurements of each speakers (the other disconnected) in axis of each :
Brown: woofer.
Green : tweeter.
And again, I don't know the curve of the mic/PC.
___________________________________________________________________
One more thing : As I've now discovered the way of designing speakers with WinISD, and as I've already own 2 car woofers of 4 ohms 38cm (curves showed in a past post) and a sub-woofer amplifier from a Kenwood sub where speakers was died, I'm building for the fun (and experimentations purposes) a big 4th order bandpass sub-woofer. That was costing me only 30$ of wood and vis/glue.
That should give this :
In red the actual supposed curve of my speaker.
In blue the sub I'm building.
I should finish it today or tomorrow.
Thanks,
Regards,
Christophe.
I've listened about 10h now and I'm very happy at least there are bass now and I really believed that was not possible before asking here. So once again thanks a lot !!
I've just (for now and for test purpose) put a 9.1 ohms resistor in series with the tweeter after plotting the curve response at around the XO freq. (And I'm still at -6dB on the XO).
Now my XO is like this :
An externally hosted image should be here but it was not working when we last tested it.
It seem that the real XO freq. is about 1050-1100 Hz as I've plotted the curve with and without reversing the polarity of the tweeter, and when inverted, there is a big gap at around this frequency.
Once again, I really don't thinking about using the Altec/lansing 908-8A and 511 as since my first try the Pioneer sound very better, and after looked at the spec. that seem to be normal.
Sorry, but no, I really don't know how I could archieve that.Pano said:
I own an little graphic equalizer, but only 7 bands (60,150,400,1k,2.4k,6k,15k).
For what purpose did you ask ?
I'd read the thread about the XO (2 firsts page for now, for understand how that works) :
My 15" have a cone breakup at ~1.6kHz and my Tweeter could go at 800Hz, but this is just after it's cutoff (500-600Hz) so not 1 octave beyond.
Anyway in it's spec. they said XO "800Hz or more".
But is the result would be really worth ?
I'd been made curves with HOLMImpulse, here the results from ~1m in front of the speaker (~in the axix of 15"). But as I don't know how interpret this curves (apart the response), I don't know what that mean (or is it good or not).
I'd not yet damped the tweeter (nor mechanically as GM recommend, nor electronically as my 9.1 ohms resistor lower the damping I believe) :
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Here are measurements of each speakers (the other disconnected) in axis of each :
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Brown: woofer.
Green : tweeter.
And again, I don't know the curve of the mic/PC.
___________________________________________________________________
One more thing : As I've now discovered the way of designing speakers with WinISD, and as I've already own 2 car woofers of 4 ohms 38cm (curves showed in a past post) and a sub-woofer amplifier from a Kenwood sub where speakers was died, I'm building for the fun (and experimentations purposes) a big 4th order bandpass sub-woofer. That was costing me only 30$ of wood and vis/glue.
That should give this :
An externally hosted image should be here but it was not working when we last tested it.
In red the actual supposed curve of my speaker.
In blue the sub I'm building.
I should finish it today or tomorrow.
Thanks,
Regards,
Christophe.
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