I'm using 8546'es too
Hi,
check out my speakers at my website . I also use 18w/8546'es
I can tell you that you will indeed encounter baffle diffraction. And you will also have to deal with it in the crossover. Also, the value of 6dB is a little high, but not by much.
I have had my speakers tested once, and John Murphies formula is quite correct.
I recommend that when you have finished your speakers, you should have them properly tested and design a crossover with a computersoftware package.
Not just by using the textbook formulas. (although they do give a decent startingpoint)
I still have to finish my speakertestjig, but when I've completed that, I will measure the speakers myself and start over on my crossover, using LspCad standard. (now that I know a little more about designing them)
Hi,
check out my speakers at my website . I also use 18w/8546'es
I can tell you that you will indeed encounter baffle diffraction. And you will also have to deal with it in the crossover. Also, the value of 6dB is a little high, but not by much.
I have had my speakers tested once, and John Murphies formula is quite correct.
I recommend that when you have finished your speakers, you should have them properly tested and design a crossover with a computersoftware package.
Not just by using the textbook formulas. (although they do give a decent startingpoint)
I still have to finish my speakertestjig, but when I've completed that, I will measure the speakers myself and start over on my crossover, using LspCad standard. (now that I know a little more about designing them)
I see a lot of speakes today are using the side firing woofers that NHT first popularised for another system (not one that was dicussed earlier using 12" woofers and Scan Speak drivers) I am thinking of using a slightly different driver topology.
If one remembers the Allison 9 (Roy Allison had a very popular company in the 80s) it had a woofer than was a 45 deg. angle with the floor. An easy way to visualise this is imagine a front facing woofer at floor level, now if that woofer base of that cabinet was not as deep as the reat teh woofer would be firing at an angle facing somewhat downwards.
Anyway if one had a 8 or 10" woofer that was facing downwards at 45 deg. then one topped of teh cabinet wiht a 6" 2way (in my cse Vifa TC series) one could have a credible 2.5way. Using sheilded 6" 2 way one could use these speakers close to a TV fo Home Theater.
Just another idea. The concept of a 2.5 way is too simple and solves too many problems (difraction sensitivity, bass output, retaining imaging of 2 way monitors, speed of bass assuming the drivers are decent) to be ignored.
Let me know if anyone has other ideas.
Regards
Navin
If one remembers the Allison 9 (Roy Allison had a very popular company in the 80s) it had a woofer than was a 45 deg. angle with the floor. An easy way to visualise this is imagine a front facing woofer at floor level, now if that woofer base of that cabinet was not as deep as the reat teh woofer would be firing at an angle facing somewhat downwards.
Anyway if one had a 8 or 10" woofer that was facing downwards at 45 deg. then one topped of teh cabinet wiht a 6" 2way (in my cse Vifa TC series) one could have a credible 2.5way. Using sheilded 6" 2 way one could use these speakers close to a TV fo Home Theater.
Just another idea. The concept of a 2.5 way is too simple and solves too many problems (difraction sensitivity, bass output, retaining imaging of 2 way monitors, speed of bass assuming the drivers are decent) to be ignored.
Let me know if anyone has other ideas.
Regards
Navin
Hi Navin,
1 - bass section. It should be ok: with the dimension you gave, and assuming a 2 cm wall thickness, taking out 10-12 litres for the Scan subvolume, you should have about 100 lt physical volume available for the woofer.
The simulation gives a Fc of 35Hz and a Qtc of 0.79 for the box completely filled with dumping material. The Qtc seems a bit high, but this time the real world is nicer than the simulation. In effect, in case of big volumes and big qty of dumping material, the real behavior of the system is different than the simulation, and you can expect both Fc and Qtc a bit lower than expected. It is difficult to predict, but I think we can assume 33Hz and 0.75.
1b - A couple of hints: with your cabinet layout you have 2 big walls (the laterals) that are likely to vibrate. Better counter this, i.e. using some 3x3 cm fillets to connect the 2 walls, displaced irregularly to better break the resonances.
Also a good thing is to cover the interior of the walls with those tar sheets that are used by car body-repairer to silence the car plates. Over here they are available at retail car do-it-yourself shops in 50x50 cm sheets, but if you know a body repairer it should be easy to get some.
Damping material : a good compromise is that kind of Dacron used for sofa, pillows etc. Ideal is to find a craftsman or small industry who works in that business and beg him to buy some from his stock. It normally come in rolls of 2x50 mts, 2-3 cm thick.
If you buy it from a HiFi retail you will pay it 50 times more.
2 - Res of the coil. Yes, a R in series to the woofer increases the electical Q, so the Qt and the related Qtc, in addition to reduce the SPL output. These effects are taken in consideration in the simulated graph, like the diffraction effects of the panel.
About helping the Scan above 100-150Hz: I don't know if this is a good idea. The Scan is limited only by his thermal ceiling in that range, and is a very well-sounding speaker. I don't know the woofer, but looking at his TS parameters looks more a sub than a woofer, and his high moving mass does not promises a high speed and transient control. I believe it's better to leave him deal with the frequencies he is designed for!
3 - Tweeter filter topology: by putting the R between C and L you obtain a 'dumping' of the filter, so changing the slope of the system (filter+speaker+panel: never forget that your REAL slope is the one of the complete system, the electrical part is jus a component of it. And at low frequencies a big part is played also by your room and the relative positions of the walls and the woofer).
Anyway, by reviewing the project, I've found that there is a better (predicted) result by placing the R in a more conventional position (after the CL cell)
4 - By using the 10 ohm in parallel you damp the impedance, but also you create an attenuator (the 1.8 series + 10 parallel), so you change the attenuation (vs 1.8 series + infinite parallel).
See usual attached graph.
Anyway, I see no reasons to damp the impedance peak: the 9900 resonates at 500 Hz, and we are filtering it at about 2500.
5 - about the 'execution' of your Morels, it could be helpful to know their specs and the filter you used to see if there was some strange thing.
I have a suspect: which ampli you were using? By experience I've killed much more tweeters with a low power amp in clipping than with big monsters.
6 - As soon as I can (probably late in the afternoon) I will send you separately the file with graphs etc. My problem is that the only way I know to send a 'print screen' is to copy it into a word or excel file. If you can teach me a smartest way I will be grateful forever!
bye
sandro
1 - bass section. It should be ok: with the dimension you gave, and assuming a 2 cm wall thickness, taking out 10-12 litres for the Scan subvolume, you should have about 100 lt physical volume available for the woofer.
The simulation gives a Fc of 35Hz and a Qtc of 0.79 for the box completely filled with dumping material. The Qtc seems a bit high, but this time the real world is nicer than the simulation. In effect, in case of big volumes and big qty of dumping material, the real behavior of the system is different than the simulation, and you can expect both Fc and Qtc a bit lower than expected. It is difficult to predict, but I think we can assume 33Hz and 0.75.
1b - A couple of hints: with your cabinet layout you have 2 big walls (the laterals) that are likely to vibrate. Better counter this, i.e. using some 3x3 cm fillets to connect the 2 walls, displaced irregularly to better break the resonances.
Also a good thing is to cover the interior of the walls with those tar sheets that are used by car body-repairer to silence the car plates. Over here they are available at retail car do-it-yourself shops in 50x50 cm sheets, but if you know a body repairer it should be easy to get some.
Damping material : a good compromise is that kind of Dacron used for sofa, pillows etc. Ideal is to find a craftsman or small industry who works in that business and beg him to buy some from his stock. It normally come in rolls of 2x50 mts, 2-3 cm thick.
If you buy it from a HiFi retail you will pay it 50 times more.
2 - Res of the coil. Yes, a R in series to the woofer increases the electical Q, so the Qt and the related Qtc, in addition to reduce the SPL output. These effects are taken in consideration in the simulated graph, like the diffraction effects of the panel.
About helping the Scan above 100-150Hz: I don't know if this is a good idea. The Scan is limited only by his thermal ceiling in that range, and is a very well-sounding speaker. I don't know the woofer, but looking at his TS parameters looks more a sub than a woofer, and his high moving mass does not promises a high speed and transient control. I believe it's better to leave him deal with the frequencies he is designed for!
3 - Tweeter filter topology: by putting the R between C and L you obtain a 'dumping' of the filter, so changing the slope of the system (filter+speaker+panel: never forget that your REAL slope is the one of the complete system, the electrical part is jus a component of it. And at low frequencies a big part is played also by your room and the relative positions of the walls and the woofer).
Anyway, by reviewing the project, I've found that there is a better (predicted) result by placing the R in a more conventional position (after the CL cell)
4 - By using the 10 ohm in parallel you damp the impedance, but also you create an attenuator (the 1.8 series + 10 parallel), so you change the attenuation (vs 1.8 series + infinite parallel).
See usual attached graph.
Anyway, I see no reasons to damp the impedance peak: the 9900 resonates at 500 Hz, and we are filtering it at about 2500.
5 - about the 'execution' of your Morels, it could be helpful to know their specs and the filter you used to see if there was some strange thing.
I have a suspect: which ampli you were using? By experience I've killed much more tweeters with a low power amp in clipping than with big monsters.
6 - As soon as I can (probably late in the afternoon) I will send you separately the file with graphs etc. My problem is that the only way I know to send a 'print screen' is to copy it into a word or excel file. If you can teach me a smartest way I will be grateful forever!
bye
sandro
Actually that is the only way. I can read word and excel files with Star Office so that is no problem. I had written a program in my early days to capture the screen and all that but it is licensed to Karl Heinz Fink of ALR-Jordan who gave me the drivers. Actually he gave me the drivers and did not want money. The I found out that he need a small progrm written so I wrote the program and gifted him the source code. Of late he is not doing well so I try not to disturb him.
The tweeters were Morel MDT33 circa 1988. I blew them in 1990 usig a Harmon Kardon PM 665 integrated amp that was rated at 100W / 8 ohms 150W at 4 ohms. The drivers were crossed over using a simple 18db XO. 8.2uf, 0.43mh, 24uf and was in MTM with 2 Focal 8N515 woofers. This was my 1st system (my requirements were high sensitivity 92db+, high power handling 100W, 2 way).
I know i wold have to use some bracing so effectively me box volume will reduce by 10% for bracing and driver.
yes teh scan is a far better driver than the 12" except it can produce a lot of bass so it makes snese to use the 12" only for the last octave or one and half octave.
Thanks for your help.
The tweeters were Morel MDT33 circa 1988. I blew them in 1990 usig a Harmon Kardon PM 665 integrated amp that was rated at 100W / 8 ohms 150W at 4 ohms. The drivers were crossed over using a simple 18db XO. 8.2uf, 0.43mh, 24uf and was in MTM with 2 Focal 8N515 woofers. This was my 1st system (my requirements were high sensitivity 92db+, high power handling 100W, 2 way).
I know i wold have to use some bracing so effectively me box volume will reduce by 10% for bracing and driver.
yes teh scan is a far better driver than the 12" except it can produce a lot of bass so it makes snese to use the 12" only for the last octave or one and half octave.
Thanks for your help.
Hi Navin,
I am just 48hr late, not too bad for an Italian!
I have sent you a wordfile with graphs, hope it's clear.
1 - Your new project
Is now simulated with the real woofer parameters, and I have corrected some of my assumptions.
Basically the mid-high x-over is a bit lower, and I have reworked the low-mid filtering the mid with a cap.
The tweeter is now attenuated with a serie/parallel net (c'mon, is 'partitore resistivo' in Italian but I have no clue about how to name it in english!). Now we have the right attenuation and the impedance peak damped (Fig.1)
Also the C and L values are changed.
Midrange has now a high pass section with a 313 Micro (a 500 cap is too big to attenuate the bass freq, it is practically useless), and the coil on the woofer is 6mH. I still recommend to try the choice with free mid + 9mH coil on woofer, maybe you can alternatively try both solutions and pick up the best sounding one.
The tweeter should work safely, since is attenuated by 10 dB at 2 kHz (Fig. 5) , see the situation of the old Morel in Fig.7 for comparison.
Also the other control simulations seems to say that the project should be correct, better refinements are up to the best existing measurement system (the ear)
Let me know if some of the graphs is not clear.
2 - Morel's death.
I have simulated the MDT33 with the data provided by www.morelusa.com, and with the filter you used (Fig.7)
Well, the MDT33+filter was surely not protected, if your nephew cranked up volume and tone control it is possible that the tweeter had more power that he could handle.
But who knows? It could also be that your speakers were from a non lucky bass, I had problems with Audax and Macrom (a Morel brand name for car hifi) burning and a super expensive Focal 10" woofer whose suspension simply detached from the cone. We 'opened' 5 woofers before Focal recognized that the batch had a glue quality problem!
By the way I well remember the MDT33, it is a great tweeter, while the HK was very good amp.
Hope I have helped you, but I want to give one last hint: try to get and learn a good CAD software, it is really impossible to design a speaker only with handwritten calculations.
The one I use is very complete and accurate, but is written in Italian. If you know somebody that can help you with the language (or you have time to invest for the translation) let me know and I'll send you a copy of mine to try before you buy your one (since the cost is only $40 it makes no sense to be a pirate)
The author is a hifi review : http://www.audioreview.it/
But most likely somebody in the list can help you in the choice of a good CAD in english!
bye
sandro
I am just 48hr late, not too bad for an Italian!
I have sent you a wordfile with graphs, hope it's clear.
1 - Your new project
Is now simulated with the real woofer parameters, and I have corrected some of my assumptions.
Basically the mid-high x-over is a bit lower, and I have reworked the low-mid filtering the mid with a cap.
The tweeter is now attenuated with a serie/parallel net (c'mon, is 'partitore resistivo' in Italian but I have no clue about how to name it in english!). Now we have the right attenuation and the impedance peak damped (Fig.1)
Also the C and L values are changed.
Midrange has now a high pass section with a 313 Micro (a 500 cap is too big to attenuate the bass freq, it is practically useless), and the coil on the woofer is 6mH. I still recommend to try the choice with free mid + 9mH coil on woofer, maybe you can alternatively try both solutions and pick up the best sounding one.
The tweeter should work safely, since is attenuated by 10 dB at 2 kHz (Fig. 5) , see the situation of the old Morel in Fig.7 for comparison.
Also the other control simulations seems to say that the project should be correct, better refinements are up to the best existing measurement system (the ear)
Let me know if some of the graphs is not clear.
2 - Morel's death.
I have simulated the MDT33 with the data provided by www.morelusa.com, and with the filter you used (Fig.7)
Well, the MDT33+filter was surely not protected, if your nephew cranked up volume and tone control it is possible that the tweeter had more power that he could handle.
But who knows? It could also be that your speakers were from a non lucky bass, I had problems with Audax and Macrom (a Morel brand name for car hifi) burning and a super expensive Focal 10" woofer whose suspension simply detached from the cone. We 'opened' 5 woofers before Focal recognized that the batch had a glue quality problem!
By the way I well remember the MDT33, it is a great tweeter, while the HK was very good amp.
Hope I have helped you, but I want to give one last hint: try to get and learn a good CAD software, it is really impossible to design a speaker only with handwritten calculations.
The one I use is very complete and accurate, but is written in Italian. If you know somebody that can help you with the language (or you have time to invest for the translation) let me know and I'll send you a copy of mine to try before you buy your one (since the cost is only $40 it makes no sense to be a pirate)
The author is a hifi review : http://www.audioreview.it/
But most likely somebody in the list can help you in the choice of a good CAD in english!
bye
sandro
I hope you are still talking baout the project involving the 12" Audio Concpets woofer, ScanSpeak 6" and Scan Speak tweeter.
The second project (for the small room 150 sq. ft) is using all drivers (8" Eminence woofer, 6" and 4" Vifa TC series woofers, and Vifa TC series tweeters) to which I have few if any specs. it is not critical and I will play it by ear. i still have not decided on the design.
back to the first project.
I am thinking of getting LspCad but dont know anyone who has used it. It is also not very expensive. It is often not the expense but the govt. foriegn exchange regulations that prevent me for paying for this.
I agree with teh midrange Cap. I was thinking 250uf (470uf x 2 is series + 10uf polyester + 2 uf wonder cap) but I can always add 50uf more of polyester cap. so i can use 470uf x 2 is series + 7 x 10uf polyester caps and 2 uf of wonder caps = 307uf. Actually the 10uf caps are about 10.2-10.7uf so it will add to 310-315uf. only it will be a lot of caps (10 caps). the biggest polyester caps here are 10uf but are of good quality.
will check your file and email later.
Regards
Navin
The second project (for the small room 150 sq. ft) is using all drivers (8" Eminence woofer, 6" and 4" Vifa TC series woofers, and Vifa TC series tweeters) to which I have few if any specs. it is not critical and I will play it by ear. i still have not decided on the design.
back to the first project.
I am thinking of getting LspCad but dont know anyone who has used it. It is also not very expensive. It is often not the expense but the govt. foriegn exchange regulations that prevent me for paying for this.
I agree with teh midrange Cap. I was thinking 250uf (470uf x 2 is series + 10uf polyester + 2 uf wonder cap) but I can always add 50uf more of polyester cap. so i can use 470uf x 2 is series + 7 x 10uf polyester caps and 2 uf of wonder caps = 307uf. Actually the 10uf caps are about 10.2-10.7uf so it will add to 310-315uf. only it will be a lot of caps (10 caps). the biggest polyester caps here are 10uf but are of good quality.
will check your file and email later.
Regards
Navin
Hi Navin, I post the answers here because I saw this thread has a lot of hits, so I assume that our discussion is interesting for somebody other.
Q: Response decrease 2 db from 400 Hz to 40 Hz
A: If you like to see a straight line in the simulation, just eliminate the cap on the midrange and use a 7mH on woofer!
Q: sound quality of capacitors
A: the critical ones are those in series to the signal, that is the tweeter and the big 300-400 for the mid.
This caps should be of the best quality possible (that's why I try always to eliminate the midrange high pass cap: 400 micro made by Solen's are bigger than the box and more expensive than the speaker!)
Caps in parallel are not so critical, polyester is of adequate quality.
Q: What about L3=0.43, R1=1ohms and R2=15ohms how will this affect the upper midrange area.
A: According to the CAD simulation, the best combination is L3=.27 , R1=1, R2=15.
With L3=.43 you have an increase of the tweeter response below 2.5 kHz and a DECREASE of 0.5 db of the global response
in the overlapping area with midrange. (the two emissions are not in phase in that range)
Anyway you're right in planning to switch the 2 coils and listen to
what's best: we're talking of small changes in the simulated behavior, too small to trust blindly the CAD.
Q
ne advantage of using R1 before the LC combination is that one can adjust the sensitivity of the tweeter without affecting the Q of the crossover. Is there any disadvantage?
A: No, but then we have to recalculate all the simulation of mid-tw x-over: it is not given that the global response stay the same if you move the attenuator before the cell.
Q: The R1/R2 combination brings the sensitivy of the tweeter down by how much db?
A: about 2 db (see fig 1, the output is about 2 db below the zero line)
Q: Given the midrange is 88db and the tweeter is 91db and this is some difraction compensation does the tweeter require more reduction? We have ...only 1 6" midrange and 1 12" woofer...
A: The mid is nominally 88db, but is 90db at 1,7 kHz and 92 at 3kHz
The tweeter is nominally 91, but is 92 in the 2-3 kHz range, 91 @ 4k and 90 above that, with a peak of 92 at 17k
The only meaningful reference to use to balance the level is the freq. response graph, nominal spl is meaningless.
Simply because of the higher than nominal spl of both speakers in the 1.5-3 kHz range, we have to dimension the filter to tune their level.
Just think that to achieve our correct 2.3 kHz ACOUSTIC x-over point, the tweeter filter cuts nominally at 3.5 kHz, and the upper mid cuts nominally at 1450 Hz!
Look the graphs at http://www.d-s-t.com/main/index.htm for your speakers.
And believe me, the Scan's response is extremely flat, a Focal kevlar 7" can sound great, but first you have to deal with a peak of +10 db in that freq range!
Q: BTW I downloaded LSPCad but need LAUD (*.frp) files for the drivers I have.
Do you know where I can get this?
A: I don't know LSP cad, but I think that you can simulate your driver inside the program (reproducing the graphs mentioned above) and then save them as .frp
Or maybe someone in the forum can forward you the files.
With my CAD I can export in Clio, Leap and Ono-Sokki (?) format, plus other formats used by local CADs. Let me know if you can import some of the above.
bye
sandro
Q: Response decrease 2 db from 400 Hz to 40 Hz
A: If you like to see a straight line in the simulation, just eliminate the cap on the midrange and use a 7mH on woofer!
Q: sound quality of capacitors
A: the critical ones are those in series to the signal, that is the tweeter and the big 300-400 for the mid.
This caps should be of the best quality possible (that's why I try always to eliminate the midrange high pass cap: 400 micro made by Solen's are bigger than the box and more expensive than the speaker!)
Caps in parallel are not so critical, polyester is of adequate quality.
Q: What about L3=0.43, R1=1ohms and R2=15ohms how will this affect the upper midrange area.
A: According to the CAD simulation, the best combination is L3=.27 , R1=1, R2=15.
With L3=.43 you have an increase of the tweeter response below 2.5 kHz and a DECREASE of 0.5 db of the global response
in the overlapping area with midrange. (the two emissions are not in phase in that range)
Anyway you're right in planning to switch the 2 coils and listen to
what's best: we're talking of small changes in the simulated behavior, too small to trust blindly the CAD.
Q
ne advantage of using R1 before the LC combination is that one can adjust the sensitivity of the tweeter without affecting the Q of the crossover. Is there any disadvantage?A: No, but then we have to recalculate all the simulation of mid-tw x-over: it is not given that the global response stay the same if you move the attenuator before the cell.
Q: The R1/R2 combination brings the sensitivy of the tweeter down by how much db?
A: about 2 db (see fig 1, the output is about 2 db below the zero line)
Q: Given the midrange is 88db and the tweeter is 91db and this is some difraction compensation does the tweeter require more reduction? We have ...only 1 6" midrange and 1 12" woofer...
A: The mid is nominally 88db, but is 90db at 1,7 kHz and 92 at 3kHz
The tweeter is nominally 91, but is 92 in the 2-3 kHz range, 91 @ 4k and 90 above that, with a peak of 92 at 17k
The only meaningful reference to use to balance the level is the freq. response graph, nominal spl is meaningless.
Simply because of the higher than nominal spl of both speakers in the 1.5-3 kHz range, we have to dimension the filter to tune their level.
Just think that to achieve our correct 2.3 kHz ACOUSTIC x-over point, the tweeter filter cuts nominally at 3.5 kHz, and the upper mid cuts nominally at 1450 Hz!
Look the graphs at http://www.d-s-t.com/main/index.htm for your speakers.
And believe me, the Scan's response is extremely flat, a Focal kevlar 7" can sound great, but first you have to deal with a peak of +10 db in that freq range!
Q: BTW I downloaded LSPCad but need LAUD (*.frp) files for the drivers I have.
Do you know where I can get this?
A: I don't know LSP cad, but I think that you can simulate your driver inside the program (reproducing the graphs mentioned above) and then save them as .frp
Or maybe someone in the forum can forward you the files.
With my CAD I can export in Clio, Leap and Ono-Sokki (?) format, plus other formats used by local CADs. Let me know if you can import some of the above.
bye
sandro
yes so we have 2 crossovers to choose from. I'd rather use the 7mh cap and eliminate the 300uf cap from the midrange. If I find the midrange getting strssed I cxna switch to the other corssover.
If was to use 200uf average non polarised cap and bypass it with a 40-50uf polyester and then bypass that with a 2uf wonder cap is thaat good enough. will the 200uf cap also have to be of good quality?
Keep R1 = 1ohms and R2 = 15ohms I can switch inductoers and see the difference in the sound. the room effects might make one sound better.
if R1 before the LC network has nt bad effects why dont most compaanies use this. then they can adjust sensitivy of the tweeter (tweeter level) easily.
so your corssover also inculdes the drivers individual response. i was wondering about that. i saw the graphs and could see the rising response of the midraange and the response of the tweeter at the crossover point. In that case even the impedanace for teh corssover is not the nominal impednace but the impedance of the drvier at the crossover point right?
Thanks again. This is an education. I dint know Scan Speak and Peerless are managed by the same company.
If was to use 200uf average non polarised cap and bypass it with a 40-50uf polyester and then bypass that with a 2uf wonder cap is thaat good enough. will the 200uf cap also have to be of good quality?
Keep R1 = 1ohms and R2 = 15ohms I can switch inductoers and see the difference in the sound. the room effects might make one sound better.
if R1 before the LC network has nt bad effects why dont most compaanies use this. then they can adjust sensitivy of the tweeter (tweeter level) easily.
so your corssover also inculdes the drivers individual response. i was wondering about that. i saw the graphs and could see the rising response of the midraange and the response of the tweeter at the crossover point. In that case even the impedanace for teh corssover is not the nominal impednace but the impedance of the drvier at the crossover point right?
Thanks again. This is an education. I dint know Scan Speak and Peerless are managed by the same company.
zeta
I seem to prefer high zeta corssoves. given the components so far teh zeta is quite low. Can a high zeta version (bigger tweeter inductor) be made?
If I increase teh tweeter inductace from 0.25 to 0.45 then the tweeter cap mus tbe reduced to copensate right? I know it is not that simple but presently my tweeter crossover has 1mh inductor and a 5uf cap.
effectively my present tweeter crossover is:
5uf cap, 1mh inductor, 1ohm series resistor, 10ohm parallel resistor.
The tweeter is used with 2 6" (18W8546) in MTM.
Regards
navin
I seem to prefer high zeta corssoves. given the components so far teh zeta is quite low. Can a high zeta version (bigger tweeter inductor) be made?
If I increase teh tweeter inductace from 0.25 to 0.45 then the tweeter cap mus tbe reduced to copensate right? I know it is not that simple but presently my tweeter crossover has 1mh inductor and a 5uf cap.
effectively my present tweeter crossover is:
5uf cap, 1mh inductor, 1ohm series resistor, 10ohm parallel resistor.
The tweeter is used with 2 6" (18W8546) in MTM.
Regards
navin
Hi Navin,
how is the project? Already sounding or still in building phase?
About your last post: increasing L and proportionally decreasing C (assuming to keep the same Fc) you lower the electric Q of the filter, that is the respose will decrease around Fc (the knee is smoothered)
For instance, in our last example moving from
C=6.8 L=.33 Fc= 3349 Q = .77
to
C=4 L= .57 Fc = 3333 Q = .45
the tw response will be:
same at 1.2 k, - 2 db @ 1.6k -4/5db from 2k to 5k, -2 @ 8k, same @ 14k.
the system response will be affected accordingly, that means that if you want a very low electric Q on the tw filter you should change the mid-bass x-over to compensate for the level decrease in the crossover range.
I'll try to simulate something with the 'low zeta' input, but at this point why don't simply try a 1st order crossover?
bye
sandro
how is the project? Already sounding or still in building phase?
About your last post: increasing L and proportionally decreasing C (assuming to keep the same Fc) you lower the electric Q of the filter, that is the respose will decrease around Fc (the knee is smoothered)
For instance, in our last example moving from
C=6.8 L=.33 Fc= 3349 Q = .77
to
C=4 L= .57 Fc = 3333 Q = .45
the tw response will be:
same at 1.2 k, - 2 db @ 1.6k -4/5db from 2k to 5k, -2 @ 8k, same @ 14k.
the system response will be affected accordingly, that means that if you want a very low electric Q on the tw filter you should change the mid-bass x-over to compensate for the level decrease in the crossover range.
I'll try to simulate something with the 'low zeta' input, but at this point why don't simply try a 1st order crossover?
bye
sandro
one idea....
is there any advatage of making the 12" side firing woofer into a tranmission line?
it is quite simple to do this.
all one needs is to partition the sub box into 3 sections using 2 vertical wood pieces that run top to bottom.
of these the vertical that is closest to the 12" is tapered so that the transmission line is wider at the bottom and less wide at the top. sort of tapering the TL.
if the dimension are 28" deep then the 3 sections would be
14" 7" and 7". The first vertical (closer to the front baffle if one were to look at teh side view) woudl tapered so it is 14" at the bottom but 10.5" at the top the second vertical would be parellel with teh rear wall of the speaker. the TL would then taper from 14" to 7" for about 5 feet and then stay at 7" for the last 2.5 feet.
also one can extend the line so that it fire out of teh top of the speaker (by reducing the depth of the cabinet of teh 6" woofer).
If one needed to convert the cabinet back to a sealed cabinet all one as to do is bore 4" holes in the verticals and close the top.
since the cabinet is about 6-6.5" wide internally a 4" hole in the center of the vertical would work.
is this idea worth the effort?
is there any advatage of making the 12" side firing woofer into a tranmission line?
it is quite simple to do this.
all one needs is to partition the sub box into 3 sections using 2 vertical wood pieces that run top to bottom.
of these the vertical that is closest to the 12" is tapered so that the transmission line is wider at the bottom and less wide at the top. sort of tapering the TL.
if the dimension are 28" deep then the 3 sections would be
14" 7" and 7". The first vertical (closer to the front baffle if one were to look at teh side view) woudl tapered so it is 14" at the bottom but 10.5" at the top the second vertical would be parellel with teh rear wall of the speaker. the TL would then taper from 14" to 7" for about 5 feet and then stay at 7" for the last 2.5 feet.
also one can extend the line so that it fire out of teh top of the speaker (by reducing the depth of the cabinet of teh 6" woofer).
If one needed to convert the cabinet back to a sealed cabinet all one as to do is bore 4" holes in the verticals and close the top.
since the cabinet is about 6-6.5" wide internally a 4" hole in the center of the vertical would work.
is this idea worth the effort?
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