Hi guys
I built my first speaker last year. unfortunately despite being well constructed the cabinet was totally out of alignment for the driver. I didn't really understand that a cabinet designed for a an Alpair 6.1 wasn't suitable for an Alpair 6p.
I have made many changes to cables, dacs, amps ect but of course to no avail.
I finally got a minidsp and added a sealed sdx7 for a sub, with very heavy equalisation it sounds OK.
I chose the wrong drivers and the wrong cabinets.The minidsp can do a great deal but is this level of equalisation desirable ?
I can't help thinking a fresh start is needed.
I built my first speaker last year. unfortunately despite being well constructed the cabinet was totally out of alignment for the driver. I didn't really understand that a cabinet designed for a an Alpair 6.1 wasn't suitable for an Alpair 6p.
I have made many changes to cables, dacs, amps ect but of course to no avail.
I finally got a minidsp and added a sealed sdx7 for a sub, with very heavy equalisation it sounds OK.
I chose the wrong drivers and the wrong cabinets.The minidsp can do a great deal but is this level of equalisation desirable ?
I can't help thinking a fresh start is needed.
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A little EQ with gentle slopes and not too much is ok. How much EQ are you applying (gain and Q)? Avoid EQ'ing in 500Hz to 5 kHz range unless it is just gentle shelf for BSC. Avoid peak boost and apply cuts.
I've got my 6p's in prototype boxes that were originally for the 6M, and they don't sound bad at all. Can you link to the box design that you used?
jeff
Hi Jeff thank you for your reply.
Here is the link
http://www.diyaudio.com/forums/full-range/138750-small-mltl-mark-audio-alpair-6-drivers.html
I think that I would have been better of with the 6m. My 6p are very treble happy and have a sharp peak around 3khz. I understand that many people are happy with them and am not saying they are a bad driver but probably the wrong choice for me.
Thank you for your reply X I do not have access to my main Pc at the moment will post the figures tomorrow.
Simon
how much different is your 6.1 cabinet from what's recommended for a 6p?
re:eq - if it sounds worse overall then probably not effective
re:eq - if it sounds worse overall then probably not effective
Never heard this before, but my drivers are in Planet_10 Mar-Ken boxes. I've always thought they sounded quite smooth, with no obvious dips or peaks. No experience with them in an MLTL like Jim's.
jeff
Hi X the mains and sub cross at 100hz I have a huge boost of +14db 140hz q 9.5 and sharp dip at 3khz -4db Q5.
It seems pretty extreme to me but actually sounds okay.
Simon
I guess that a more suitable enclosure may provide a even response. Also this is my first experience of full range drivers, my previous were mission 751 which were certainly smoother.
Simon
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Hello Freddi
As far I know there isn't an MLTL designed for the 6p although apparently they might work in a Pensil 6.
Here are the stats for Alpair 6p
power handling (continuous/programme) = 15 W
frequency range = 100-22000 Hz
resonance frequency fs = 74 Hz
impedance R = 4 Ohm
sound pressure level SPL = 86 dB (2,83V; 1m)
DC resistance Re = 3,8 Ohm
force factor BL = 2,67 N/A
voice coil inductance L = 0,0069 mH
effective piston radiating area Sd = 36,3 cm2
effective mechanical mass incl. air load mms = 2,32 g
equivalent volume of compliance Vas = 3,6 l
total Q factor Qts = 0,43 (Qms=1,78, Qes=0,57)
voice coil diameter = 18 mm
maximum peak linear excursion vibration xlin = +/- 4 mm
And the Alpair 6.1
power handling (continuous/programme) = 15/30 W
frequency range = 80-20000 Hz
resonance frequency fs = 74 Hz
impedance R = 4 Ohm
sound pressure level SPL = 86 dB (2,83V; 1m)
DC resistance Re = 3,6 Ohm
force factor BL = 2,87 N/A
voice coil inductance L = 0,6255 mH
effective piston radiating area Sd = 38 cm2
effective mechanical mass incl. air load mms = 2,93 g
equivalent volume of compliance Vas = 3,3 l
total Q factor Qts = 0,48 (Qms=2,5, Qes=0,6)
maximum peak linear excursion vibration xlin = +/- 5 mm
Simon
The rule of thumb is to EQ out the peaks and leave the nulls alone. Chances are pretty good that you will not hear a sharp hole like that. You will be throwing a lot of power at your speaker and creating quite a bit of distortion around the null.
This is one reason I have stopped using the REW room EQ. It wastes too many PEQ's on nulls and then doesn't have enough to smooth out the peaks.
Bob
Interesting Bob, I'm not sure I've heard that rule of thumb before. I've always been a fan of the parametric eq's and perhaps I can see the thinking there but if you have a 31 band graphic, aren't you trying flatten the response?
Disclaimer: I learned long ago that flat is not to my liking.
Disclaimer: I learned long ago that flat is not to my liking.
Bob is right and I use that rule too and mainly limit EQ from 500Hz to 5kHz with wide (low Q) and gentle shelves if needed for BSC as that is where the ear is most sensitive to phase distortions. At lower freq avoid peak boosts like the plague as cone excursion is increased where distortion is at its worst. Some drivers are -55dB HD at higher frequencies so they can take a little peak boosting if needed without too much HD penalty. "Chop mountains and do not fill valleys."
Have you ever taken an FR of speakers in a room, looked at all the hills an valleys, and said "It really doesn't sound that bad!"? Well, it doesn't because your brain ignores the valleys and tries to level the peaks. And this is the crux of the matter.Your brain ignores narrow nulls. Fills in the information from the remainder of the harmonic structure. Trying to fill the null with EQ is just going to heat the voice coil and increase IM distortion.
The brain is not so tolerant to narrow peaks. A narrow peak of any substantial size can be very audible and poses a real challenge to EQ. Note that by reducing excursion, you tend to reduce heating, etc. However, any substantial change in the FR by EQ runs the risk of screwing up the phase structure, and that is also audible.
Amen to that. There are some very expensive speakers with very flat FR plots that are simply boring. Whether you like a bit of added warmth, a BBC dip, some added presence, the sound is better with a bit of spice.
Bob
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I seem to like a bit of bumpiness at the mid-low end - at least I have a large open back speaker and it sounds boring when I put the back on so I leave it off 😱
130 to 150hz will almost always exhibit a dip when measuring a speaker where the driver is mounted close to ear height. This is why I measure <200Hz at the cone - 1inch or so, obviously at a lower SPL - and merge the response with the 1m result. You can also hoist the speaker on a foot stool or other kind of stand to minimize this null 🙂 the response below 200 has more to do with the room boundaries than the raw speaker response, IMO.
The main probelm with EQ (in the bass region) is that if you get is spot on for one setup (speaker position, room, listener position), it won't be right for a slightly different one. Like has been said, a gentle correction (such as with tone controls) is generally more desirable than complex adjustment for this reason. EQ is best done taking the layout variables out of the equation. Then apply tone control correction if really necessary.
At the bottom of the spectrum the model dominates. Moving the mic up/down or forward and back will shift this null to a higher or lower frequency. No amount of power will fix this. Better to cut the level of any peak once measured at the listening position. The reasoning is that the ear is rather insensitive to these sharp nulls but very sensitive to peaks.
My listening space is wacked, typical apt livingroom. Only eq applied below 200 is a cut of 4dB at 30Hz. Depending on program material turn it off, especially after being woke up by some crack head hammering away from 3:30 til 4:30am lastnight.
Best is to use eq to smooth out the gross issues with broad low Q filters and then nip the peaks. You'll most likely need to get creative with the filters, 6 bands aren't enough often times.
My listening space is wacked, typical apt livingroom. Only eq applied below 200 is a cut of 4dB at 30Hz. Depending on program material turn it off, especially after being woke up by some crack head hammering away from 3:30 til 4:30am lastnight.
Best is to use eq to smooth out the gross issues with broad low Q filters and then nip the peaks. You'll most likely need to get creative with the filters, 6 bands aren't enough often times.
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