Gurus,
Thankyou all for the inputs. I'm going to take it one at a time.
Navin,
So I can conclude I will have a decent output at 50hz from the P21, albeit 3db down.
I have some idea about the KLH EQ you mention. Is'nt it something like altering the 'Q' to bump the response a few db's up. Well, I have a Active kit I'm trying to put together and am struggling to. It is the John Pomann kit from snippets.org. I'm not very adept at doing this kind of stuff. In fact the bass-unit I'm building is my first shot at this wonderful hobby.
If any of the DIY'ers from Bangalore can help with the kit, that would be great.
About the drivers customs worries me. How do we solve that ?
Mcp,
Thanx for the link. My faith is restored. The P21WO-20-08 is so much talked about, but the 39-08, not much. In fact the only differences I see is the "sensitivity" & "nominal power" rating of both. Funny they both ultimately add up to 96db.
Bose,
Thanx for the offer. My room is approx 5x3 metres. My reason for not opting for a lower f3 is standing waves which I'm pretty certain will overpower the room. My choice of music is quite varied & when I play something bass-heavy I don't want the neighbours thinking T-rex is on a visit next door. How low exactly is 50hz ?
What are you thought on stuffing the TL's ? I've read that
stuffing a TL is an art in itself. Also, the sound can be altered quite drastically.
I posted this question on "Audio Asylum" as well & I got an answer saying it is going to be lower meaning, the room interaction will push the f3 even lower meaning at 50 it will not be 3db down.
Hmmmmmmmm.......nice.
Cheers & thanx for all the info. Think about the drivers. I'm serious....
sunil
Thankyou all for the inputs. I'm going to take it one at a time.
Navin,
So I can conclude I will have a decent output at 50hz from the P21, albeit 3db down.
I have some idea about the KLH EQ you mention. Is'nt it something like altering the 'Q' to bump the response a few db's up. Well, I have a Active kit I'm trying to put together and am struggling to. It is the John Pomann kit from snippets.org. I'm not very adept at doing this kind of stuff. In fact the bass-unit I'm building is my first shot at this wonderful hobby.
If any of the DIY'ers from Bangalore can help with the kit, that would be great.
About the drivers customs worries me. How do we solve that ?
Mcp,
Thanx for the link. My faith is restored. The P21WO-20-08 is so much talked about, but the 39-08, not much. In fact the only differences I see is the "sensitivity" & "nominal power" rating of both. Funny they both ultimately add up to 96db.
Bose,
Thanx for the offer. My room is approx 5x3 metres. My reason for not opting for a lower f3 is standing waves which I'm pretty certain will overpower the room. My choice of music is quite varied & when I play something bass-heavy I don't want the neighbours thinking T-rex is on a visit next door. How low exactly is 50hz ?
What are you thought on stuffing the TL's ? I've read that
stuffing a TL is an art in itself. Also, the sound can be altered quite drastically.
I posted this question on "Audio Asylum" as well & I got an answer saying it is going to be lower meaning, the room interaction will push the f3 even lower meaning at 50 it will not be 3db down.
Hmmmmmmmm.......nice.
Cheers & thanx for all the info. Think about the drivers. I'm serious....
sunil
I have a JAES article on that KLH thingie, written by a KLH developer named Daniel von Recklinghausen. I can find out the issue etc if you like.
It is basically a 6th order reflex alignment using a highpass filter with a hump. Additionally it is voltage-controlled by some frequency- and amplitude dependant control circuit, thereby preventing overexcursion of the (very) small woofer.
It is of course possible to make a 4th order closed-box system that way as well.
Even the excursion limiting feature could be used. For a closed box it is quite easy to derive excursion vs frequency: It is a lowpass function with the same order and Q as the amplitude response, mirrored at fsb.
I once did the maths etc on a 2nd order highpass that could also be used for the same purpose and which is even a bit simpler (a standard Sallen-Key with a tuneable resistor built around an OTA) than the KLH circuit.
Regards
Charles
It is basically a 6th order reflex alignment using a highpass filter with a hump. Additionally it is voltage-controlled by some frequency- and amplitude dependant control circuit, thereby preventing overexcursion of the (very) small woofer.
It is of course possible to make a 4th order closed-box system that way as well.
Even the excursion limiting feature could be used. For a closed box it is quite easy to derive excursion vs frequency: It is a lowpass function with the same order and Q as the amplitude response, mirrored at fsb.
I once did the maths etc on a 2nd order highpass that could also be used for the same purpose and which is even a bit simpler (a standard Sallen-Key with a tuneable resistor built around an OTA) than the KLH circuit.
Regards
Charles
If you like lower bass, vented box is perfectly alright in a room of 5x3m. The problem with standing waves is not so much in room volume but dimensions and reflectivity. Apart from a listening sofa, break up the walls with bookshelves, cabinets, anything to disperse the sound waves. You will be surprised at the difference, when compared with a completely bare room.
To give you an idea of how bad it can be, I was recently asked to revamp the sound system of a new school hall. This is a rather big hall, almost twice the size of a normal hall, with high ceiling, at least 50ft, and fully air-conditioned. I stood in the middle, clapped my hands and a full echo came back. Measured with a RTA and it registered 6ms for RT60. No amount of EQ'ing is going to solve that. An acoustic consultant was called in. My brief was "bring it down to 1ms, preferbly 0.5ms". It always amazes me that they can spend millions in building a new school, but somehow cannot build a proper hall.
To give you an idea of how bad it can be, I was recently asked to revamp the sound system of a new school hall. This is a rather big hall, almost twice the size of a normal hall, with high ceiling, at least 50ft, and fully air-conditioned. I stood in the middle, clapped my hands and a full echo came back. Measured with a RTA and it registered 6ms for RT60. No amount of EQ'ing is going to solve that. An acoustic consultant was called in. My brief was "bring it down to 1ms, preferbly 0.5ms". It always amazes me that they can spend millions in building a new school, but somehow cannot build a proper hall.
Attachments
Mcp,
I kind of like the sound of sealed bass, nice & taut, Jazz-Fusion sounds reaaaally good. I'm biased against vented because the sound always sounds "leathery".
I have'nt heard many speakers so my bias could be stupid.
Thanx for the "rush" about the room. I just realized I should investigate my room a little more. I'll post a drawing of the setup, the system, the furniture, the placement with the necessary dimensions.
Just realized, there is a dining attached and it makes the length
longer by about 2.5 metres. The problem seems to be the ratio of "height" to the "width-where-the-whole-thing-is-setup" which is 2.90m, ie...1:1 (width:height) , definitely not good.
From there, with some help, I'll workout the exact "goings-on"
and decide further on the bass-unit.
Charles,
To start with I did'nt get much of what you've written. Can you point me some-where I can understand it ?
I got the over-excursion part as I understand it is the point where the woofer is hitting against & past its "Xmax". Correct me as I go along..
The "sallen-key" is a filter alignment commonly used in "Active Equalizers". The tunable resistor helps with frequency something.... What is OTA ?
My setup is currently being modified from a Audiolab 8000C/P with a Cambridge Audio A100 to one with an "Active EQ". Right now I have a Mission 731 Pro. The bass-unit I want to build is going to add some "bottom" to music. The "Audiolabs" will make the "Missions" sing when they don't have the 400hz & lower to deal with.
Cheers,
sunil
I kind of like the sound of sealed bass, nice & taut, Jazz-Fusion sounds reaaaally good. I'm biased against vented because the sound always sounds "leathery".
I have'nt heard many speakers so my bias could be stupid.
Thanx for the "rush" about the room. I just realized I should investigate my room a little more. I'll post a drawing of the setup, the system, the furniture, the placement with the necessary dimensions.
Just realized, there is a dining attached and it makes the length
longer by about 2.5 metres. The problem seems to be the ratio of "height" to the "width-where-the-whole-thing-is-setup" which is 2.90m, ie...1:1 (width:height) , definitely not good.
From there, with some help, I'll workout the exact "goings-on"
and decide further on the bass-unit.
Charles,
To start with I did'nt get much of what you've written. Can you point me some-where I can understand it ?
I got the over-excursion part as I understand it is the point where the woofer is hitting against & past its "Xmax". Correct me as I go along..
The "sallen-key" is a filter alignment commonly used in "Active Equalizers". The tunable resistor helps with frequency something.... What is OTA ?
My setup is currently being modified from a Audiolab 8000C/P with a Cambridge Audio A100 to one with an "Active EQ". Right now I have a Mission 731 Pro. The bass-unit I want to build is going to add some "bottom" to music. The "Audiolabs" will make the "Missions" sing when they don't have the 400hz & lower to deal with.
Cheers,
sunil
sunil
Overexcursion occurs indeed when you reach the "maximum excursion before damage", or maybe even before that, depending on your requirements.
A Sallen-Key filter is the most used filter topology for 2nd order low- or high-pass filters. The filter-structure used by Sigfried Linkwitz within the following link are Sallen-Key filters:
http://www.linkwitzlab.com/filters.htm#2
An OTA is an Operational Transconductance Amplifier. It is basically some sort of opamp that doesn't have a gain defined by output-voltage/input-voltage but by a transconductance=output-current/input-voltage. I.e. it is a voltage-controlled current-source with differential inputs. The transconductance can be controlled by some kind of bias-current.
My favourite one is still the old-fashioned CA3080. It doesn't have very good specs but depending on the way you use it it does only get into action when the overexcursion protection is needed.
In this case one can live with the slightly increased distortion: a driver whose voice-coil is hitting the backplate generates definitely more of it !!
Instead of an OTA you can use a JFET or a LED/LDR (Light Dependant Resistor) combination.
Regards
Charles
Overexcursion occurs indeed when you reach the "maximum excursion before damage", or maybe even before that, depending on your requirements.
A Sallen-Key filter is the most used filter topology for 2nd order low- or high-pass filters. The filter-structure used by Sigfried Linkwitz within the following link are Sallen-Key filters:
http://www.linkwitzlab.com/filters.htm#2
An OTA is an Operational Transconductance Amplifier. It is basically some sort of opamp that doesn't have a gain defined by output-voltage/input-voltage but by a transconductance=output-current/input-voltage. I.e. it is a voltage-controlled current-source with differential inputs. The transconductance can be controlled by some kind of bias-current.
My favourite one is still the old-fashioned CA3080. It doesn't have very good specs but depending on the way you use it it does only get into action when the overexcursion protection is needed.
In this case one can live with the slightly increased distortion: a driver whose voice-coil is hitting the backplate generates definitely more of it !!
Instead of an OTA you can use a JFET or a LED/LDR (Light Dependant Resistor) combination.
Regards
Charles
What should you do !
Hi Sunil,
The following is my opinion on what you should do. This can keep you busy for some time and you can improve the sound of your system quite a bit by spending less money than buying a set of new drivers and building electronics for that.
1. You can improve your Mission 731. I have the older 701's that I modified. Big diff.
2. You can add an electronic crossover.
3. You can add a sub.
All this will make a huge improvement in sound over the stock equipment you have.
Save your P21W's for a later date or for the sub.
First of all , 50Hz is the "hum" that you hear from your speakers when you touch the inputs of your amp with your finger. It is also the local mains frequency.
You need to get down to 40 Hz or so to really hear deeper bass - far more satisfying than the 50 Hz limit. As frequencies go down , even small changes sound very different. 30 Hz and 40 Hz sound nothing like 50 Hz ! Also remember that when you say "go down to 50 Hz" it is not a brick wall filter so other frequencies will still be there in smaller quantities.
You can convert your 731 into a biwireable speaker and upgrade the speaker crossover with better parts. Polyester caps and air core inductors. If necessary you can damp the cabinet walls by gluing bitumen impregnated sheets to the walls. You have to watch out how much you add as it will cut down the internal volume. These mods should make a huge improvement in sound.
You can then crossover the 731 at Lf ( based on its acoustic roll off ) and add a sub. The P21W in a TL enclosure could be used.
There is a lot of work to be done. I can't put it all down here. Ask your questions as you go along and someone on the forum will be able to help you .
Have fun.
Cheers.
I forgot to mention that you can start by building a tall sand filled speaker stand. The tweeter of your speaker should be at about ear level when placed on the stand. My stands weigh about 20Kg each. You could use large diameter PVC pipes ( 5" ?) for the central column - just a suggestion!
Hi Sunil,
The following is my opinion on what you should do. This can keep you busy for some time and you can improve the sound of your system quite a bit by spending less money than buying a set of new drivers and building electronics for that.
1. You can improve your Mission 731. I have the older 701's that I modified. Big diff.
2. You can add an electronic crossover.
3. You can add a sub.
All this will make a huge improvement in sound over the stock equipment you have.
Save your P21W's for a later date or for the sub.
First of all , 50Hz is the "hum" that you hear from your speakers when you touch the inputs of your amp with your finger. It is also the local mains frequency.
You need to get down to 40 Hz or so to really hear deeper bass - far more satisfying than the 50 Hz limit. As frequencies go down , even small changes sound very different. 30 Hz and 40 Hz sound nothing like 50 Hz ! Also remember that when you say "go down to 50 Hz" it is not a brick wall filter so other frequencies will still be there in smaller quantities.
You can convert your 731 into a biwireable speaker and upgrade the speaker crossover with better parts. Polyester caps and air core inductors. If necessary you can damp the cabinet walls by gluing bitumen impregnated sheets to the walls. You have to watch out how much you add as it will cut down the internal volume. These mods should make a huge improvement in sound.
You can then crossover the 731 at Lf ( based on its acoustic roll off ) and add a sub. The P21W in a TL enclosure could be used.
There is a lot of work to be done. I can't put it all down here. Ask your questions as you go along and someone on the forum will be able to help you .
Have fun.
Cheers.
I forgot to mention that you can start by building a tall sand filled speaker stand. The tweeter of your speaker should be at about ear level when placed on the stand. My stands weigh about 20Kg each. You could use large diameter PVC pipes ( 5" ?) for the central column - just a suggestion!
Re: What should you do !
you can do the EQ with a sealed bass units too. results will change depending on unit. if you are feeding bass up to 400Hz to the 21cm driver you are now talking about BSC (Baffle Step Comp). If I were you and were looking at mating the 731 to teh 8" I'd look at one of the 2 options.
leave the XO of 731 as it is (you may make the mods ashok siggested esp to the flimsy cab) and use the P21 to augment the bass belw 100hz via an acitve filter/EQ and seperate power amp.
alternately you can modify the XO of the 731 and let teh P21 take compensate for baffle step insted of the XO.
In both cases the P21 can be built into a stand for teh 731. in option 1 the P21 could be kept as close to the floor as possible (I prefer the method used by Roy Allison in their Allison 9 speaker in the70s) in option 2 the P21 should be as close to the midbass in fact it might make sense to fire the P21 towards the rear wall to compensate for phase anomalies of teh 6db/octave BSC.
I have left the details out of of this but you can either email me in private of shoose an option and we can investigate that further. it depends on if you want to expolre the 731s XO, you want to just augment bass or the midbass as well, if you have a spare power amp, etc.
BTW I am quite happy with a calulated (read as anechoic) F3 of 40Hz or so. In most rooms the F3 changes a bit usually get a bit lower and much more lumpy. below that you needs serius tube traps etc to keep the room for getting excited.
or you could combine the 2 and built a tall TL if you fold the line you could get a Tl of about 48"and then using damping increase effective lenght to about 96" enough for your needs. teh advatage of TL is you can play with damping to extend response to suit YOUR room.
if you are looking at the "TL in a stand idea" then one way to add mass without sandis to use 1.5mm thick lead sheet. a 3' x 8' sheet would weigh 40kgs and one such sheet per bass box would do. i built an aperiodic bass box like this once. 2 layers of lead between 3 layers of 8 mm MDF. 10" wide, 14" deep, 36" tall. 2 x 8" Emincene woofers. oops i digress again!
sunil said:
you can do the EQ with a sealed bass units too. results will change depending on unit. if you are feeding bass up to 400Hz to the 21cm driver you are now talking about BSC (Baffle Step Comp). If I were you and were looking at mating the 731 to teh 8" I'd look at one of the 2 options.
leave the XO of 731 as it is (you may make the mods ashok siggested esp to the flimsy cab) and use the P21 to augment the bass belw 100hz via an acitve filter/EQ and seperate power amp.
alternately you can modify the XO of the 731 and let teh P21 take compensate for baffle step insted of the XO.
In both cases the P21 can be built into a stand for teh 731. in option 1 the P21 could be kept as close to the floor as possible (I prefer the method used by Roy Allison in their Allison 9 speaker in the70s) in option 2 the P21 should be as close to the midbass in fact it might make sense to fire the P21 towards the rear wall to compensate for phase anomalies of teh 6db/octave BSC.
I have left the details out of of this but you can either email me in private of shoose an option and we can investigate that further. it depends on if you want to expolre the 731s XO, you want to just augment bass or the midbass as well, if you have a spare power amp, etc.
BTW I am quite happy with a calulated (read as anechoic) F3 of 40Hz or so. In most rooms the F3 changes a bit usually get a bit lower and much more lumpy. below that you needs serius tube traps etc to keep the room for getting excited.
ashok said:
or you could combine the 2 and built a tall TL if you fold the line you could get a Tl of about 48"and then using damping increase effective lenght to about 96" enough for your needs. teh advatage of TL is you can play with damping to extend response to suit YOUR room.
if you are looking at the "TL in a stand idea" then one way to add mass without sandis to use 1.5mm thick lead sheet. a 3' x 8' sheet would weigh 40kgs and one such sheet per bass box would do. i built an aperiodic bass box like this once. 2 layers of lead between 3 layers of 8 mm MDF. 10" wide, 14" deep, 36" tall. 2 x 8" Emincene woofers. oops i digress again!
Charles,
Thanx for the info. I’m going to work it into the crossover I’m making.
Ashok,
The 731’s are already bi-wirable. They use iron-core inductors & I’m not so sure whether this has already been compensated in the crossover. You think modifying the stock internal cable alone will make a big difference.
What are you thoughts/views on using CAT5 for the modification or good satellite cable ?
Are good Polyester caps available in Bangalore ? Where do you get your inductors made ? The idea is to have an active cross-over & maybe with the overexcursion protection built in as Charles suggested. I have the kit & need help to do it.
Can you suggest someone ?
Navin,
Yes, I have a spare amp. I need the bass-unit to actually do the work of the lower octaves. Now, you say that baffle diffraction has to be compensated because the XO point is 400hz. Incase I choose the P17’s over the P13, they have an fs of 37 & going by the graphs given by Vifa, 200 seems to be a good point, the impedance being nice & consistent. If this is the case, would I still need the compensation. I am using an active crossover though.
In an earlier post you mention the drivers W4 657S or 654S. Who makes these ?
Do you actually measure the T/S params before you go about designing or go by the manufacturers specs ?
So how do we go about getting the drivers ?
Cheers,
sunil
Thanx for the info. I’m going to work it into the crossover I’m making.
Ashok,
The 731’s are already bi-wirable. They use iron-core inductors & I’m not so sure whether this has already been compensated in the crossover. You think modifying the stock internal cable alone will make a big difference.
What are you thoughts/views on using CAT5 for the modification or good satellite cable ?
Are good Polyester caps available in Bangalore ? Where do you get your inductors made ? The idea is to have an active cross-over & maybe with the overexcursion protection built in as Charles suggested. I have the kit & need help to do it.
Can you suggest someone ?
Navin,
Yes, I have a spare amp. I need the bass-unit to actually do the work of the lower octaves. Now, you say that baffle diffraction has to be compensated because the XO point is 400hz. Incase I choose the P17’s over the P13, they have an fs of 37 & going by the graphs given by Vifa, 200 seems to be a good point, the impedance being nice & consistent. If this is the case, would I still need the compensation. I am using an active crossover though.
In an earlier post you mention the drivers W4 657S or 654S. Who makes these ?
Do you actually measure the T/S params before you go about designing or go by the manufacturers specs ?
So how do we go about getting the drivers ?
Cheers,
sunil
sunil said:
1. replace the caps with poly one from CTR. They are yellow in colour and come in values from 0.5uf to 10uf.
2. replace wire with soild core for the HF unit (I use Belden) and better qualtiy multi strand for the midbass. However if you are going to XO at 400hz u cn use a solid core for the mid too. The reason here is most soild core cable (I am not talking bus bar) tends to have a higher impedance (thick solid core cable is very stiff and a pain in the butt 2 use) and this impedance affects the damping factor which can adversly affect bass response of the system. At 400Hz it is ok to use solid core 100Hz it is not.
3. replace iron core inductors with air core keep in mind that the DCR should be less than 0.1 ohms for series inductors and 0.5ohms for parallel inductors. one easy way to build cheap air core inductors (ugly but cheap) is to use old E-type transformer formers minus the E core and use a multidtrand (I have used 3x18) wire to wind and you can wind this by hand. The "better" way is to use a lathe.
4. baffle step is dependent on baffle width. f=c/w. c = speed of sound. baffle step then continues down to about f=c/18w. total loss is about 6db. say w = 6" c=1180ft/s. f=2360 so teh baffle step comes into play at 2360Hz and then falls till about 131hz the total fall being 6db. for a 8" wiide cabinet it is 100-1800Hz.
if the response is 0db at 1800Hz it would be about 1.5db down at 900, about 3db down at 450hz, 4.5db down at 225Hz and about 6db down at 112.5Hz.
what many manufcturers do is either use a second woofer at about 400Hz this compensates for loss of LF response or use a dual voice coil woofer and roll the second coil at about 350-400Hz this resolves teh issue of a LR ckt for baffle step (or in many cases what is done is a oversized inductor as a rough compensation for baffle step) so if calulations dictate that the series inductor with woofer should be 0.7-1mh the indctor you will often find is 2-2.5mh. This large inductor i feel dampens teh sound.
now it also so happens that about 50% of the energy in music is below 300hz. so if one had 2 similar amps one could let one amp operate the fullrange speaker and the second amp (via an active 6db XO or via a PLLXO at 300hz) operate the baffle step compensation woofer.
Tangband (www.tb-spekaer.com) makes the W4 657 etc... they are cheap full rane drivers. however if I was making a system of a bigger budget I'd use the JX92 from Jordan.
I used to use LEAP/LMS to maeasure T/S specs. I find specs from even reputed guys to be off more than 20%. this does matter as much for selaed boxes but for bass reflex it can be a disaster. The friend who had LEAP/LMS moved so I dont ahve use of it anymore. If I get drivers from Europe (read as Germany) I use MLSSA at a friends place in Germany. Yes I prefer to measure all my drivers individually.
I import what I need officially. What I usually do is collect a bunch of drivers at a friends place in teh US or in Germany and then air-ship a lot of say 12 drivers together. for example the last time I imported drivers I shipped 6 SS 8546, 2 SS 9900, 2 SS 9500, 2 Audax 170Z0 together. this saves on shipping costs. if the drivers are larger say 10 or 12" then I ship 6 or so at one go.
i pay my duties like one would/should pay his/her taxes. you live in India you gotta take the good (food, people, services) with the bad (infrastrcuture, govt., bureaucracy). When I first moved to India taxes were as high at 63% (due to double taxation on a lot of my income) we still retained our integrity and principles, today at 35% it's best to just pay and smile.
Some more suggestions.
Hi Sunil,
I see a lot of things being suggested as the thread progresses and I am probably loosing touch with what is really the issue. Anyway here are my suggestions:
1. You say you have two amplifiers. Choose the one that sounds better in mids and highs ( if there is a difference )! Use the better sounding one with the Missions and use the other for bass.
2. I would recommend a Linkwitz Riley 4th order crossover. You could seal the duct of the Mission and see what you get
- Fs and Q. Using that you can make a LR filter to give a true LR 4th order rolloff. It will limit bass excursion and you will probably never be able to physically reach its Xmax.
3. The Sub will also use a 4th order LR filter - this should be straight forward.
4. About the internal cables. I think this is highly debated and I will not give my opinions but some facts that I have observed. The old Allison One speaker ( highly regarded at the time ) used a single core wire for all drivers ( including 10 inch woofers ) . It must have been 0.5mm in diameter! It sounded very good. I have used single core and multistrand ( about 1mm overall) in my speakers and could not really notice anything significant with either cable. I think with short lengths of less than 18 inches or so , its effects are largely swamped by other higher impedances in the system. You can wire each unit with different type cables and see if they sound significantly different .
5. The inductors must be air core . Any other type will not be as linear as an air core type. Make these even if they are physically large. Chances are that they will not be too large. Remove the one in your speaker and measure the inductance and dc resistance.
6. As Navin said , you can use CTR capacitors. If you don't get the value , use several in parallel to get what you want. Remove all bipolar type caps and replace them. You get these at Texonic Instruments,
and many other component shops around SJP road. CTR capacitors are used a lot for industrial applications. I found a CTR cap in my Rogers GS-1 speaker crossover ! So you know they are good. I would use a 100 volt rating . A 63 volt unit should normally handle all signals but it better to have a sufficient marging in the rating. After 63V you only get a 100 volt rating.
7. About CAT 5 cable. I will try that one of these days. I use fairly thick OFC copper cable I bought from the market. They are about Rs55/- per meter and have a transparent PVC insulation. I use short lengths ( only about 2m ) for each speaker. The effects of cables should be less as you keep decreasing its length. So use as short a length as physically possible , but keep both lengths ( left and right ) equal. The amp at the speaker base is the ideal situation. Cables could affect the sound in some systems. You will need to check and see how much it affects your system. Remember that the altered sound using some cables does not necessarily mean that it is better than the standard thick multistrand cable. You will need to measure the frequency response at the speaker terminals to see what has happened. Sometimes it all boils down to what you percieve to be better ( attractive ) with your ears.
8. I make my own inductors. There are lots of programs to design inductors using a specified wire size and former dimensions. You can use the one at
http://members.optusnet.com.au/~audiosoft/inductor.exe
I use a 1/2 inch aluminum tube ( wall thickness is not important ) . I cut out two discs in 3mm ply or 3mm plastic ( more difficult to work with ) and drill a 1/2 inch hole in them and araldite the aluminum tube to it . Diameter of the discs depends on how deep the coil will be. Typically it might be 2 1/2 to 3 inches for the woofer coil and 1 1/2 to 2 inches for the tweeter. Wind 5 or 10 % more than the program tells you. Strip the insulation of the enamel wire at both ends of the coil and connect it to an inductance meter. Unwind slowly till you get what you want.
You can select the wire size and see what the dc resistance will be ( from the program ). You should measure the dc resistance of the existing inductor and try to get something similar to it. It does not have to be very exact. Note that these are AIR CORE coils. I seal the coils with a bit of instant glue so that it does not unwind. Be careful as the glue can run down the coil and drip from the bottom.
9. Over excursion . If you seal the duct and make the 4th order LR filter , you will not need any over excursion protection at all. Note that the electronic filter for the sub will be a 4th order type and the one for the satellite will be a 2nd order filter. If the Q of your sealed Mission is not 0.707 or thereabouts , the Q of the second order filter will have to be manipulated to get an overall 4th order LR response. You will not have to worry about baffle diffraction at all. Keep your sub in a separate enclosure near the satellite. Note that you can have a stereo sub ( a sub for each channel ) which many purists prefer. Again this is hotly debated. If you have the drivers and space to keep two boxes , why not ! The additional amp is stereo I guess. You have nothing to loose and everything to gain.
I could not find the specs of the 731 Pro but I guess its sealed resonance will be less than 100Hz. You can use any round solid object almost as big as the duct and wrap a layer of foam around it and push it in. An inch or two deep is enough. Do you have the means of measuring the impedance curve ? You can use any of the free software on the web with your PC sound card to do this. Try www.dazyweb.com or www.rightmark.com .
What else do you need to know ? The TL - yes I will come to that shortly. I wanted to build one but it keeps getting delayed.
Cheers,
Ashok.
Hi Sunil,
I see a lot of things being suggested as the thread progresses and I am probably loosing touch with what is really the issue. Anyway here are my suggestions:
1. You say you have two amplifiers. Choose the one that sounds better in mids and highs ( if there is a difference )! Use the better sounding one with the Missions and use the other for bass.
2. I would recommend a Linkwitz Riley 4th order crossover. You could seal the duct of the Mission and see what you get
- Fs and Q. Using that you can make a LR filter to give a true LR 4th order rolloff. It will limit bass excursion and you will probably never be able to physically reach its Xmax.
3. The Sub will also use a 4th order LR filter - this should be straight forward.
4. About the internal cables. I think this is highly debated and I will not give my opinions but some facts that I have observed. The old Allison One speaker ( highly regarded at the time ) used a single core wire for all drivers ( including 10 inch woofers ) . It must have been 0.5mm in diameter! It sounded very good. I have used single core and multistrand ( about 1mm overall) in my speakers and could not really notice anything significant with either cable. I think with short lengths of less than 18 inches or so , its effects are largely swamped by other higher impedances in the system. You can wire each unit with different type cables and see if they sound significantly different .
5. The inductors must be air core . Any other type will not be as linear as an air core type. Make these even if they are physically large. Chances are that they will not be too large. Remove the one in your speaker and measure the inductance and dc resistance.
6. As Navin said , you can use CTR capacitors. If you don't get the value , use several in parallel to get what you want. Remove all bipolar type caps and replace them. You get these at Texonic Instruments,
and many other component shops around SJP road. CTR capacitors are used a lot for industrial applications. I found a CTR cap in my Rogers GS-1 speaker crossover ! So you know they are good. I would use a 100 volt rating . A 63 volt unit should normally handle all signals but it better to have a sufficient marging in the rating. After 63V you only get a 100 volt rating.
7. About CAT 5 cable. I will try that one of these days. I use fairly thick OFC copper cable I bought from the market. They are about Rs55/- per meter and have a transparent PVC insulation. I use short lengths ( only about 2m ) for each speaker. The effects of cables should be less as you keep decreasing its length. So use as short a length as physically possible , but keep both lengths ( left and right ) equal. The amp at the speaker base is the ideal situation. Cables could affect the sound in some systems. You will need to check and see how much it affects your system. Remember that the altered sound using some cables does not necessarily mean that it is better than the standard thick multistrand cable. You will need to measure the frequency response at the speaker terminals to see what has happened. Sometimes it all boils down to what you percieve to be better ( attractive ) with your ears.
8. I make my own inductors. There are lots of programs to design inductors using a specified wire size and former dimensions. You can use the one at
http://members.optusnet.com.au/~audiosoft/inductor.exe
I use a 1/2 inch aluminum tube ( wall thickness is not important ) . I cut out two discs in 3mm ply or 3mm plastic ( more difficult to work with ) and drill a 1/2 inch hole in them and araldite the aluminum tube to it . Diameter of the discs depends on how deep the coil will be. Typically it might be 2 1/2 to 3 inches for the woofer coil and 1 1/2 to 2 inches for the tweeter. Wind 5 or 10 % more than the program tells you. Strip the insulation of the enamel wire at both ends of the coil and connect it to an inductance meter. Unwind slowly till you get what you want.
You can select the wire size and see what the dc resistance will be ( from the program ). You should measure the dc resistance of the existing inductor and try to get something similar to it. It does not have to be very exact. Note that these are AIR CORE coils. I seal the coils with a bit of instant glue so that it does not unwind. Be careful as the glue can run down the coil and drip from the bottom.
9. Over excursion . If you seal the duct and make the 4th order LR filter , you will not need any over excursion protection at all. Note that the electronic filter for the sub will be a 4th order type and the one for the satellite will be a 2nd order filter. If the Q of your sealed Mission is not 0.707 or thereabouts , the Q of the second order filter will have to be manipulated to get an overall 4th order LR response. You will not have to worry about baffle diffraction at all. Keep your sub in a separate enclosure near the satellite. Note that you can have a stereo sub ( a sub for each channel ) which many purists prefer. Again this is hotly debated. If you have the drivers and space to keep two boxes , why not ! The additional amp is stereo I guess. You have nothing to loose and everything to gain.
I could not find the specs of the 731 Pro but I guess its sealed resonance will be less than 100Hz. You can use any round solid object almost as big as the duct and wrap a layer of foam around it and push it in. An inch or two deep is enough. Do you have the means of measuring the impedance curve ? You can use any of the free software on the web with your PC sound card to do this. Try www.dazyweb.com or www.rightmark.com .
What else do you need to know ? The TL - yes I will come to that shortly. I wanted to build one but it keeps getting delayed.
Cheers,
Ashok.
Navin,
Thanx for the info about CTR. I’m going to change the caps in the Missions & see how much diff it makes. About the t/s params, I don’t have the luxury of either software so am stuck with designing the crossover with the manufacturer specs.
About the baffle diff. I’m going to use an active XO for the P21’s so I have to include the baffle compensation in it. Maybe it is better to just XO at 100hz & save myself a lot of trouble. In which case I’ll go in for the P17 instead of the P13’s.
Since the P17’s have an fs of 37, will, using an active L/R 4th order be sufficient to keep the T/Mid out of the lower octaves. Another thing is, it will be only about 1 ½ octaves away from the resonant frequency & going by the imp. chart by vifa there is a terrific spike in imp at fs. Is this an issue ?
About the drivers, if there is no problem with paying the duties involved & getting the drivers in, I don’t mind. I usually buy my stuff from Australia, www.wescomponents.com (SS & Vifa), www.gsoaudio.com (Vifa Premium Line), www.me-au.com (Audax), www.nqld.com (Seas). I haven’t had any experience with buying from the US. What do you think will be the cost for shipping once it reaches here ? Lets do it.
Ashok,
I have 2 amps. I will put the Audiolab on the t/mid & the other one on the bass-unit. Are you suggesting I actually redo the XO on the Missions to a LR 4th order.
" You could seal the duct of the Mission and see what you get
- Fs and Q "
How am I going to calculate the fs & Q ? I don’t have any instruments to do it. The active XO I have is a 4th order LR. Can you help me find someone who can assemble it for me ?
I’m comfortable working with speaker design because I understand some of the principles & the way the design works. In electronics I’m pretty blank. I know the virtues of using an active XO, but nothing further than that.
The over-excursion problem discussed in an earlier post was for the P21’s. I was just thinking that if the “fs” is 26fz & it is being designed in a closed box for an f3 of 50hz, will it ever reach its Xmax. Please correct me.
I definitely need help with the active XO, so please let me know of anyone who can do it for me. I need a volume control & also incorporate the baffle diff. compensation in it.
Cheers,
sunil
You could seal the duct of the Mission and see what you get " You could seal the duct of the Mission and see what you get - Fs and Q"
Thanx for the info about CTR. I’m going to change the caps in the Missions & see how much diff it makes. About the t/s params, I don’t have the luxury of either software so am stuck with designing the crossover with the manufacturer specs.
About the baffle diff. I’m going to use an active XO for the P21’s so I have to include the baffle compensation in it. Maybe it is better to just XO at 100hz & save myself a lot of trouble. In which case I’ll go in for the P17 instead of the P13’s.
Since the P17’s have an fs of 37, will, using an active L/R 4th order be sufficient to keep the T/Mid out of the lower octaves. Another thing is, it will be only about 1 ½ octaves away from the resonant frequency & going by the imp. chart by vifa there is a terrific spike in imp at fs. Is this an issue ?
About the drivers, if there is no problem with paying the duties involved & getting the drivers in, I don’t mind. I usually buy my stuff from Australia, www.wescomponents.com (SS & Vifa), www.gsoaudio.com (Vifa Premium Line), www.me-au.com (Audax), www.nqld.com (Seas). I haven’t had any experience with buying from the US. What do you think will be the cost for shipping once it reaches here ? Lets do it.
Ashok,
I have 2 amps. I will put the Audiolab on the t/mid & the other one on the bass-unit. Are you suggesting I actually redo the XO on the Missions to a LR 4th order.
" You could seal the duct of the Mission and see what you get
- Fs and Q "
How am I going to calculate the fs & Q ? I don’t have any instruments to do it. The active XO I have is a 4th order LR. Can you help me find someone who can assemble it for me ?
I’m comfortable working with speaker design because I understand some of the principles & the way the design works. In electronics I’m pretty blank. I know the virtues of using an active XO, but nothing further than that.
The over-excursion problem discussed in an earlier post was for the P21’s. I was just thinking that if the “fs” is 26fz & it is being designed in a closed box for an f3 of 50hz, will it ever reach its Xmax. Please correct me.
I definitely need help with the active XO, so please let me know of anyone who can do it for me. I need a volume control & also incorporate the baffle diff. compensation in it.
Cheers,
sunil
You could seal the duct of the Mission and see what you get " You could seal the duct of the Mission and see what you get - Fs and Q"
ok we'll make life a little simpler now.... 
1. since you dont have any measuring tools it might make sense to just replace the XO parts in the mission 731 with CTR, aircore, etc... copy the values on the orignal parts.
2. for over excursion protection i'd suggest a simple PLLXO in the audiolab input. this can be quite simply there is a lot of info on google on this. i suggest 100Hz can be a good starting point. if you feel that 1st order Passive is not enough you can move to 2nd order. that should do it.
3. for the sub 4th order as ashok suggested is ok since it is active.
4. if you have not got the drivers yet and are using teh woofer for the bass only can I suggest the M18 instead of the P17. I dont know if the price difference is significant.
1. since you dont have any measuring tools it might make sense to just replace the XO parts in the mission 731 with CTR, aircore, etc... copy the values on the orignal parts.
2. for over excursion protection i'd suggest a simple PLLXO in the audiolab input. this can be quite simply there is a lot of info on google on this. i suggest 100Hz can be a good starting point. if you feel that 1st order Passive is not enough you can move to 2nd order. that should do it.
3. for the sub 4th order as ashok suggested is ok since it is active.
4. if you have not got the drivers yet and are using teh woofer for the bass only can I suggest the M18 instead of the P17. I dont know if the price difference is significant.
Navin,
1) Yes, I’ll do the mods on the Missions, the simple ones.
2) About the P21’s, since the f3 is 26 & I’m getting a sealed output of 50hz@f3 do you still think I it because I keep thinking that it will not reach its potential, ever. Correct me anytime I veer offcourse.
3) Yup, I’ll use a 4th order on the sub.
4) Now, the big one. I wanted the T/M’s to have as small a profile as possible. Started off with the P13’s crossed at 200-300 but with the baffle-step issue I decided on the P17’s. The M18’s are even bigger.
The specs are impressive on paper.It has a larger magnet than the P17’s but works the same cone area (better control). The Kapton former & 40mm (1 ½” ) coil should comfortably handle high spl’s. It has an f3 of 66 which is super. The cone material is treated paper, which I understand handles cone break-up better.
What are your thought’s / experiences on cone break-up of drivers this big ?
Why do you think the M18’s are better ? I’m open for ideas as they don’t cost much more than the P17’s, in fact A$ 20/- more.
Cheers,
sunil
1) Yes, I’ll do the mods on the Missions, the simple ones.
2) About the P21’s, since the f3 is 26 & I’m getting a sealed output of 50hz@f3 do you still think I it because I keep thinking that it will not reach its potential, ever. Correct me anytime I veer offcourse.
3) Yup, I’ll use a 4th order on the sub.
4) Now, the big one. I wanted the T/M’s to have as small a profile as possible. Started off with the P13’s crossed at 200-300 but with the baffle-step issue I decided on the P17’s. The M18’s are even bigger.
The specs are impressive on paper.It has a larger magnet than the P17’s but works the same cone area (better control). The Kapton former & 40mm (1 ½” ) coil should comfortably handle high spl’s. It has an f3 of 66 which is super. The cone material is treated paper, which I understand handles cone break-up better.
What are your thought’s / experiences on cone break-up of drivers this big ?
Why do you think the M18’s are better ? I’m open for ideas as they don’t cost much more than the P17’s, in fact A$ 20/- more.
Cheers,
sunil
The drivers.
Hi Sunil,
The crossover point between satellite and sub is preferably lower than about 120 Hz. This is to make sure that the sub does not start beaming signals which will ( apart from other things ) make its position apparent. If you crossoved over around 100Hz , you could very well use the P13 W which is very well known for its great performance. Play the P13W ( I have some ) directly with an amp and no crossover. You will find that it sounds better than many other drivers played the same way.
There are also designs available off the net for the P13W.
Your sub better go down at least to 30 ~40Hz . If it does not it cannot really be called a SUB. A sealed box with room gain could give you bass down to 30 Hz depening on the room size etc. A reflex enclosure will give you more LF. If done properly , with room gain , it will sound pretty good and need less power to achieve it. A reflex enclosure can always be converted to a sealed unit easily. The only catch is that you cannot increase the volume easily. You could however simulate the reflex and sealed unit and compare the performance in a room. You will find a big difference between a 6 inch and a 8 inch driver used as a sub.
If this is the first time you are making something - don't get into too many details. Understand what you are doing and do the easiest and most prefered thing. You can always upgrade later on. For DIY there is always a "later on" !
The smaller the satellite the better. The P13 is ideal IMO.
It will however sound best with an active crossover. If you plan to make the P13 enclosure yourself it is easy to design the second order crossover for it.
What did you say about the 4th order crossover ? You already have a board ? What about the circuit diagram and parts?
Cheers,
Ashok.
Hi Sunil,
The crossover point between satellite and sub is preferably lower than about 120 Hz. This is to make sure that the sub does not start beaming signals which will ( apart from other things ) make its position apparent. If you crossoved over around 100Hz , you could very well use the P13 W which is very well known for its great performance. Play the P13W ( I have some ) directly with an amp and no crossover. You will find that it sounds better than many other drivers played the same way.
There are also designs available off the net for the P13W.
Your sub better go down at least to 30 ~40Hz . If it does not it cannot really be called a SUB. A sealed box with room gain could give you bass down to 30 Hz depening on the room size etc. A reflex enclosure will give you more LF. If done properly , with room gain , it will sound pretty good and need less power to achieve it. A reflex enclosure can always be converted to a sealed unit easily. The only catch is that you cannot increase the volume easily. You could however simulate the reflex and sealed unit and compare the performance in a room. You will find a big difference between a 6 inch and a 8 inch driver used as a sub.
If this is the first time you are making something - don't get into too many details. Understand what you are doing and do the easiest and most prefered thing. You can always upgrade later on. For DIY there is always a "later on" !
The smaller the satellite the better. The P13 is ideal IMO.
It will however sound best with an active crossover. If you plan to make the P13 enclosure yourself it is easy to design the second order crossover for it.
What did you say about the 4th order crossover ? You already have a board ? What about the circuit diagram and parts?
Cheers,
Ashok.
Re: The drivers.
U guys are confusing me. i thought this was a problem of mating the P17 (or M18) with teh 731. where did the P21 and P13 fit in? mating the P13 to a 731 makes little sense. Are we talking about 2 systems (1) P17+731 and (2) P21 with P13 + tweeter?
1. Mating the P13 to teh 731 does not addd much to the bass unless you have a very small box you should/couold use teh P17 or M18.
2. The M18 has a low loss surround which I prefer to teh high damping surondof the P17 or P13 esp. in bass transients. The high damping surrounds were all the rage at one time as they provided the designer a way to get ruler flat freq. response curves.
I dont think ruler flat response curves make any sense as all these curves are based on anechoic rooms anyway. I feel speakers should be built to sound like music (never mind limited bass extension etc...). If I cant listen to music on a speaker who cares how it measures. I dont measure using traditional oscillospces. I used to (while I had teh facility) use LEAP/LMS to double check driver specs. that is all.
The M18 is in my view is a better driver than the P17 esp as a bass unit. if you can afford it go for it. I'll only be jealoous. so if you find it missing you'll know where to look then again for the bas teh P21 would be prefered over the M18. bass is an issue of moving air. thnk Sd x Xmax. the bigger this product the better. Also factor in sens. if you find 2 8" drivers (1) Xmax 6mm sens 90db (2) Xmax 12mm sens 80db my guess is driver (1) will make more sense. there are calculators that will calculate what teh max SPL will be before Xmax is reached on the net.
cone breakup is a factor of cone/surround material design more than it is a factor of size. beaming is related to size. in genreal a 6-7" (18cm) wont beam much till about 1200-1500Hz. I have run a 8" (20cm) driver to 1800Hz (6db electrical) in am MTM and hardly noticed the beaming.
XO between the woofer and mid depends on teh drivers used. between the M18 and 731's woofer I'd guess 100hz is about right. 80Hz would be preferable if you are looking at limited SPLs.
the again XO between a M18 and M10 (vifa 4" mid) would be 300Hz or so. If you were using a P13 with the 731 I'd run teh 731 full range. the 731's (5" woofer) probably has similar limitations of Xmax as the P13.
all things remaining constant reflex boxes are usually bigger than sealed boxes. so one can always reduce the box volume by introducing sand (in jute bags).
for a 1st timer a sealed box is easier as it it is less dependant on correct T/S specs. depending on location of speaker in room and F3 and F10 of speaker a sealed box can provide as good a sensation of bass as a reflex box. in general I find that I can take a small (6") driver sealed box and place is close to a wall (rear only) while the same 6" in a reflex box needs to be a few feet out or it excites room nodes.
sunil said:
U guys are confusing me. i thought this was a problem of mating the P17 (or M18) with teh 731. where did the P21 and P13 fit in? mating the P13 to a 731 makes little sense. Are we talking about 2 systems (1) P17+731 and (2) P21 with P13 + tweeter?
1. Mating the P13 to teh 731 does not addd much to the bass unless you have a very small box you should/couold use teh P17 or M18.
2. The M18 has a low loss surround which I prefer to teh high damping surondof the P17 or P13 esp. in bass transients. The high damping surrounds were all the rage at one time as they provided the designer a way to get ruler flat freq. response curves.
I dont think ruler flat response curves make any sense as all these curves are based on anechoic rooms anyway. I feel speakers should be built to sound like music (never mind limited bass extension etc...). If I cant listen to music on a speaker who cares how it measures. I dont measure using traditional oscillospces. I used to (while I had teh facility) use LEAP/LMS to double check driver specs. that is all.
The M18 is in my view is a better driver than the P17 esp as a bass unit. if you can afford it go for it. I'll only be jealoous.
so if you find it missing you'll know where to look then again for the bas teh P21 would be prefered over the M18. bass is an issue of moving air. thnk Sd x Xmax. the bigger this product the better. Also factor in sens. if you find 2 8" drivers (1) Xmax 6mm sens 90db (2) Xmax 12mm sens 80db my guess is driver (1) will make more sense. there are calculators that will calculate what teh max SPL will be before Xmax is reached on the net. cone breakup is a factor of cone/surround material design more than it is a factor of size. beaming is related to size. in genreal a 6-7" (18cm) wont beam much till about 1200-1500Hz. I have run a 8" (20cm) driver to 1800Hz (6db electrical) in am MTM and hardly noticed the beaming.
ashok said:
XO between the woofer and mid depends on teh drivers used. between the M18 and 731's woofer I'd guess 100hz is about right. 80Hz would be preferable if you are looking at limited SPLs.
the again XO between a M18 and M10 (vifa 4" mid) would be 300Hz or so. If you were using a P13 with the 731 I'd run teh 731 full range. the 731's (5" woofer) probably has similar limitations of Xmax as the P13.
all things remaining constant reflex boxes are usually bigger than sealed boxes. so one can always reduce the box volume by introducing sand (in jute bags).
for a 1st timer a sealed box is easier as it it is less dependant on correct T/S specs. depending on location of speaker in room and F3 and F10 of speaker a sealed box can provide as good a sensation of bass as a reflex box. in general I find that I can take a small (6") driver sealed box and place is close to a wall (rear only) while the same 6" in a reflex box needs to be a few feet out or it excites room nodes.
Ashok / Navin,
Sorry about all the confusion. These are the facts:
1) I already have a P21 for which I'm designing the bass-cabinet
2) I own a pair of 731's to which I'll be using the bass-cabinet
3) Once the bass-unit turns out well, I want to build the top-unit
consisting of a D27TG & ............. ( P13 or P17 or M18 )
Navin,
The question is, which of the three will be best for midrange from 100hz onwards ? I plan to cross the D27's at around 2500hz.
What about getting the drivers from abroad ?
Ashok,
The graphs from Vifa don't look so good for the P13's at 100hz.
Can I trust the graphs ? Are yours crossed over at 100hz.
When you say, play it without a crossover do you mean with an Active XO or none at all ?
About the active 4th order XO, yes I have all the parts with the circuit diagram. I need help to build it. Do you know anyone, here, in Blr who can help ?
Cheers,
sunil
Sorry about all the confusion. These are the facts:
1) I already have a P21 for which I'm designing the bass-cabinet
2) I own a pair of 731's to which I'll be using the bass-cabinet
3) Once the bass-unit turns out well, I want to build the top-unit
consisting of a D27TG & ............. ( P13 or P17 or M18 )
Navin,
The question is, which of the three will be best for midrange from 100hz onwards ? I plan to cross the D27's at around 2500hz.
What about getting the drivers from abroad ?
Ashok,
The graphs from Vifa don't look so good for the P13's at 100hz.
Can I trust the graphs ? Are yours crossed over at 100hz.
When you say, play it without a crossover do you mean with an Active XO or none at all ?
About the active 4th order XO, yes I have all the parts with the circuit diagram. I need help to build it. Do you know anyone, here, in Blr who can help ?
Cheers,
sunil
The crossover.
Sunil, the immediate need right now is possibly the crossover.
Is this a 4th order LR crossover with two inputs ( left and right ) and four outputs ? Is the power supply on board ? Do you already have a transformer to power it ?What is the secondary voltage? I might be able to help.
Please download some free measurement software from the web. If you have some difficulty we can email it to you. You will need it , no matter how much help you get from the web.
Let us know.
I suggested listening to the P13 WITHOUT ANY crossover to see how it sounds. If it is not good over some frequency range it will show up immediately. A good test- to see if the driver has any bad cone breakup modes when it can sound pretty noisy when excited in that range. This is better done before you buy a driver ! You want to know it is good before you buy one.
The P17 does not sound as good as good as the P13 in this kind of test. I have both drivers . The P17 in a reflex box ( which I have ) goes quite deep but is not as good as a dedicated SUB! The P13 or P17 with a D27 is a very good combination. If you use a sub , the P13 is a better choice.
Right now get on with the Mission731. There is a lot you can get out of it. Bi amping sounds far better than biwiring and active crossovers give far better sound than passive crossovers. As you can see this can keep you busy for many months !
I'll send you some curves for the P21 and the P13 in different boxes.
Cheers.
Sunil, the immediate need right now is possibly the crossover.
Is this a 4th order LR crossover with two inputs ( left and right ) and four outputs ? Is the power supply on board ? Do you already have a transformer to power it ?What is the secondary voltage? I might be able to help.
Please download some free measurement software from the web. If you have some difficulty we can email it to you. You will need it , no matter how much help you get from the web.
Let us know.
I suggested listening to the P13 WITHOUT ANY crossover to see how it sounds. If it is not good over some frequency range it will show up immediately. A good test- to see if the driver has any bad cone breakup modes when it can sound pretty noisy when excited in that range. This is better done before you buy a driver ! You want to know it is good before you buy one.
The P17 does not sound as good as good as the P13 in this kind of test. I have both drivers . The P17 in a reflex box ( which I have ) goes quite deep but is not as good as a dedicated SUB! The P13 or P17 with a D27 is a very good combination. If you use a sub , the P13 is a better choice.
Right now get on with the Mission731. There is a lot you can get out of it. Bi amping sounds far better than biwiring and active crossovers give far better sound than passive crossovers. As you can see this can keep you busy for many months !
I'll send you some curves for the P21 and the P13 in different boxes.
Cheers.
Re: The crossover.
P21+731 is a very nice combo. if your 2 way (mid+D27TG) will mate to the P21 then use the P13 if not (if it is stand alone) then use the M18.
importing drivers? cool idea. I dont mind getting involved. right now I am looking at full rnage drivers from tangband. once my expriments with full ranges bear fruit I am considering a JX92+Esg combo or something like that.
sunil said:
ashok said:
P21+731 is a very nice combo. if your 2 way (mid+D27TG) will mate to the P21 then use the P13 if not (if it is stand alone) then use the M18.
importing drivers? cool idea. I dont mind getting involved. right now I am looking at full rnage drivers from tangband. once my expriments with full ranges bear fruit I am considering a JX92+Esg combo or something like that.
Welcome to the club. Like I said in another thread http://www.diyaudio.com/forums/showthread.php?postid=236045#post236045, I abandoned my LMS long time ago.
I would like to suggest tweeters as well. Just listen at low volume and identify the resonance.
I support that. This is how I used the P13 in a conventional 3-way.
And after you have finished building your sub and center, you may then decide to make 2 more P13 MTMs' for mains and use the Mission for surrounds. You will then have a very desirable HT system, mains and center all same MTMs'.
Downloads.
Hi Sunil,
Download Speaker workshop from
http://www.speakerworkshop.com/
On the right side of the main page ypu will find a link to a tutorial . This should be enough to start.
Then www.dazylab.com has a free Audio Analyser download . Try that also. Dont forget www.rightmark.com
I am sure this should be enough for the time being.
Cheers.
Hi Sunil,
Download Speaker workshop from
http://www.speakerworkshop.com/
On the right side of the main page ypu will find a link to a tutorial . This should be enough to start.
Then www.dazylab.com has a free Audio Analyser download . Try that also. Dont forget www.rightmark.com
I am sure this should be enough for the time being.
Cheers.
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