I´ve been reading up, but I´m not that much wiser now..
Since I already have crossovers in my Denon I guess my software of choice should be the "AutoEQ with REW" which, if I understand it correctly, can take a measurement of a frequency response and correct it to the point of being flat when it gets to the output of the device.. Simply magic!
The trouble is.. How do I know that a flat respons is what I want? Maybe a manual PEQ would be a safer choice?
Anyway, I´m ordering the Seas FA22rcz today to get started, and Ikea will get a visit this afternoon. The baffle will be 123x60.6x2.8cm and with the dsp I hope that I, with all you guys help, can make it sound ok. If not I´ll start investigating other drivers.
I also need to budget for a power amp to drive my subs.. Simulation with roomgain shows that my subs should dig a bit deeper than they actually do playing testtones (they make a noice at 20Hz, but the difference when I hit 25Hz is big to say the least and at around 35-40Hz the soundpressure starts to get lower again and keeps pretty level up to 100Hz.. I´ve never had this boost from 25 to 40Hz in my room before so the problem is not room related.
My subs play tight and musical, but they are better with rock and jazz than they are with electronic music, such as Infected mushroom.. When the frequency starts to drop, the sound gets more fat and definition, which is great higher up, gets lost. The really deep sounds seem drowned in comparison to the 25-40Hz range.
I started investigating the amp and found that it is to blame.. Apparently it has a "house curve" (it has something to do with an eq compensation for the ears lower sensitivity at low frequencies) that raises the level at 30Hz with 6dB (starting with 1dB at 45 and reaching 6dB at 30Hz) and to make things worse, a 24dB subsonic filter at 25Hz.. Neither the house-curve boost or the subsonic filter can be bypassed... I´ve noticed that the sound tightens up down low if I plug the BR-ports (then the house curve makes sense.. Still nothing in the deepest bass, though) but my subs simulate (in my room) a pretty flat response down to 20Hz so with the current amp it simply becomes too much.
A cheap, silent (no fans in my room...) PA-amp like the t.amp e400 costs about a 100$, gives me all the power that I need and does´nt have any weird filters so I feel that it would be a necessary purchase.
Well, with the Alpair drivers on the way (close to 200$), two Seas drivers that will be ordered today (another 250$) and something like the t.amp my budget is pretty much exhausted..and I´m not where I need to be yet..
Time to start hiding money from the wife..but I kind of suspected that would be the case from the beginning..
Since I already have crossovers in my Denon I guess my software of choice should be the "AutoEQ with REW" which, if I understand it correctly, can take a measurement of a frequency response and correct it to the point of being flat when it gets to the output of the device.. Simply magic!
The trouble is.. How do I know that a flat respons is what I want? Maybe a manual PEQ would be a safer choice?
Anyway, I´m ordering the Seas FA22rcz today to get started, and Ikea will get a visit this afternoon. The baffle will be 123x60.6x2.8cm and with the dsp I hope that I, with all you guys help, can make it sound ok. If not I´ll start investigating other drivers.
I also need to budget for a power amp to drive my subs.. Simulation with roomgain shows that my subs should dig a bit deeper than they actually do playing testtones (they make a noice at 20Hz, but the difference when I hit 25Hz is big to say the least and at around 35-40Hz the soundpressure starts to get lower again and keeps pretty level up to 100Hz.. I´ve never had this boost from 25 to 40Hz in my room before so the problem is not room related.
My subs play tight and musical, but they are better with rock and jazz than they are with electronic music, such as Infected mushroom.. When the frequency starts to drop, the sound gets more fat and definition, which is great higher up, gets lost. The really deep sounds seem drowned in comparison to the 25-40Hz range.
I started investigating the amp and found that it is to blame.. Apparently it has a "house curve" (it has something to do with an eq compensation for the ears lower sensitivity at low frequencies) that raises the level at 30Hz with 6dB (starting with 1dB at 45 and reaching 6dB at 30Hz) and to make things worse, a 24dB subsonic filter at 25Hz.. Neither the house-curve boost or the subsonic filter can be bypassed... I´ve noticed that the sound tightens up down low if I plug the BR-ports (then the house curve makes sense.. Still nothing in the deepest bass, though) but my subs simulate (in my room) a pretty flat response down to 20Hz so with the current amp it simply becomes too much.
A cheap, silent (no fans in my room...) PA-amp like the t.amp e400 costs about a 100$, gives me all the power that I need and does´nt have any weird filters so I feel that it would be a necessary purchase.
Well, with the Alpair drivers on the way (close to 200$), two Seas drivers that will be ordered today (another 250$) and something like the t.amp my budget is pretty much exhausted..and I´m not where I need to be yet..
Time to start hiding money from the wife..but I kind of suspected that would be the case from the beginning..
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You can increase the speaker Q by adding a resistor into the speaker lead, or use an amplifier that has a higher output impedance.
You can also increase the speaker Q by adding some weight to the moving mass.
A driver with a Qts of around 0.5 could possibly be pushed to nearer 0.7 for near optimum open baffle response if you are trying to emulate an "Butterworth" type roll-off. But this can only happen if the baffle is big enough to keep the back and front sounds from mixing at the frequencies concerned.
I was hoping for some constructive feedback on my post, but to date none has come other than Pano's EQ requirement to bring up the missing bass when using a smaller baffle width.
Any suggestion of how much EQ is required?
Any idea if a Linkwitz transform is useful?
You can also increase the speaker Q by adding some weight to the moving mass.
A driver with a Qts of around 0.5 could possibly be pushed to nearer 0.7 for near optimum open baffle response if you are trying to emulate an "Butterworth" type roll-off. But this can only happen if the baffle is big enough to keep the back and front sounds from mixing at the frequencies concerned.
I was hoping for some constructive feedback on my post, but to date none has come other than Pano's EQ requirement to bring up the missing bass when using a smaller baffle width.
Any suggestion of how much EQ is required?
Any idea if a Linkwitz transform is useful?
In a 123x60.6cm baffle I have now idea how much eq that will be required, but I have the baffles now, and tomorrow I will cut offset mounting holes. When the drivers arrive (Tuesday, if all goes well) I will make (and post) some measurements to see just how much that is needed.
I´m not sure, but is not an LT the same thing as lowering everything above the target frequency to make it level? Seems like an awful waste of power..and by simply raising the level of the bass (ok.. that takes power aswell) the total "effectiveness" (does that word exist?) will be a lot higher with a similar total frequency response. It will, of course, put more strain on both the driver and the amp but to use an LT in the mid and high range.. Wont that kill dynamics and "life"?
Again, I´m not at all sure of what an LT really means, but if it is something that can be beneficial here I would very much like to be educated.
I´m not sure, but is not an LT the same thing as lowering everything above the target frequency to make it level? Seems like an awful waste of power..and by simply raising the level of the bass (ok.. that takes power aswell) the total "effectiveness" (does that word exist?) will be a lot higher with a similar total frequency response. It will, of course, put more strain on both the driver and the amp but to use an LT in the mid and high range.. Wont that kill dynamics and "life"?
Again, I´m not at all sure of what an LT really means, but if it is something that can be beneficial here I would very much like to be educated.
I wouldn't think that you'd want to mess around with a LT circuit in the midrange. Boosting the low end in that way will negatively affect the lower midrange response. Voicing will be too heavy here. That's just my opinion though.
I've never worked with the miniDSP but you might have the option to try a 4th order BW high pass to help lift the lower midrange a little ... if that is even needed. You'd have to try/measure/listen to that to judge for yourself. A bessel xo can accomplish a peaking response as well.
I've never worked with the miniDSP but you might have the option to try a 4th order BW high pass to help lift the lower midrange a little ... if that is even needed. You'd have to try/measure/listen to that to judge for yourself. A bessel xo can accomplish a peaking response as well.
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I agree with puppet, I don't think an LT is called for for your midrange driver. On that size baffle it should roll off about where you need it to, with a few bumps and peaks, of course. Asymmetrical placement and/or wings will smooth the response.
As to your other question, no, you may not want a (measured) flat response. I certainly don't. I like a gently falling response from about 500Hz to 20Khz. What sounds balanced to your ear may not measure flat to the mic. I should measure smooth, but not necessarily flat. The mic does not work like a pair of ears on a head, connected to a brain. Similar, but not the same. Let the mic be your guide and a great help, but don't let it have the final word. The way you perceive the FR and tonal balance depends on a lot of things that don't always show up in simple measurements.
As to your other question, no, you may not want a (measured) flat response. I certainly don't. I like a gently falling response from about 500Hz to 20Khz. What sounds balanced to your ear may not measure flat to the mic. I should measure smooth, but not necessarily flat. The mic does not work like a pair of ears on a head, connected to a brain. Similar, but not the same. Let the mic be your guide and a great help, but don't let it have the final word. The way you perceive the FR and tonal balance depends on a lot of things that don't always show up in simple measurements.
"I still like the driver, but I guess a small sealed or BR enclosure simply suits it better. The drivers are affordable so I will order a pair today and try one of the more conventional builds to see what it can do. I will still try an OB though, but not with this driver."
I know I get a bit carried away and write too much..but that´s what I wrote about the Alpair. Not hard to miss.. In time they will get a sealed or a BR box but they will not be used in the OB:s. I´m sure they can sound stunning in a conventional enclosure but if they need to be brought down to a sensitivity of 77db (less at the listening position) to be able to give me the bass extension I need, then the 20w RMS power handling of the driver in combination with the low sensitivity.. They wont be able to play at the soundpressure levels I want. I listen to a lot of well recorded jazz and classical, and many of my records have crest values of at least 15dB. A sensitivity of 77dB, a maximum power rating of 20w RMS and then at least 15dB of dynamic headroom.. It simply wont work.
I´m still curious of the OB, and the Seas FA22rcz:s seem more apropriate for that type of use.
The Alpair 7 Gen 3:s and the FA22:s will be two separate builds. First the OB, and while I try to make them work I will gather the funds to have a carpenter build me som nice enclosures for the Alpairs..
That´s the plan. Nothing wrong with having 2 pairs of good speakers..
Yup, I definitely was slow on the uptake there.
Given the following the MarkAudio drivers have around here, I thought that that Alpair must have a certain amount of magic to it. So I thought perhaps you'd decided to stay OB but to also go with a helper woofer to fill in the bottom end and still keep the sensitivity high enough, what some folks here call a FAST system. Not knowing anything about dsp, I thought you might be intending to use that for the XO.
That'll teach me to pay a little more attention. Doh!
As a full range driver the Seas definitely meets your frequency requirements better than the Alpair. I'll be interested in hearing what you think of the finished product.
Cheers
Given the following the MarkAudio drivers have around here, I thought that that Alpair must have a certain amount of magic to it. So I thought perhaps you'd decided to stay OB but to also go with a helper woofer to fill in the bottom end and still keep the sensitivity high enough, what some folks here call a FAST system. Not knowing anything about dsp, I thought you might be intending to use that for the XO.
That'll teach me to pay a little more attention. Doh!
As a full range driver the Seas definitely meets your frequency requirements better than the Alpair. I'll be interested in hearing what you think of the finished product.
Cheers
That´s the plan. Nothing wrong with having 2 pairs of good speakers..
Sorry Shylock. 2 pairs aint good enough...you will need 4 pairs...of each kind...dipoles, monopoles, omnipoles...before you think something is wrong
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