Like the trapezoidal baffle - adds something to the looks, a bit Art Deco. I'm not sure about CLD using liquid nails, doesn't it dry hard? I was going to do a double skinned baffle and use green glue for the job which doesn't set.
I don't have the means to measure mine but in general I'm happy with the balance so I'll be sticking with original port size during rebuild.
Great that the sound balance on yours is good. You can tell that by ear pretty well. If you like it, that's all that matters.
You are probably right about LN drying hard. It would form a impedance mismatch with soft foam core to dampen the transmission of sound at least. Sounds really dull to the knuckle rap test. Latex caulking is the other stuff I have used that stays soft. The trapezoidal baffle on baffle effect is functional and adds a distinct look. I like the free hand cut bevels (faceted) edges myself. One tricky thing with wall mount speakers is to hang them in such a way that they don't vibrate on bass notes. Usually I put a small round disc of foam from earplugs on bottom corners where it touches wall and have picture hanger wire on top two corners.
Hi XRK,
After the results with my chucked together prototype (3 pages back) I was sufficiently impressed to do a better build. Fractionally resized but keeping to the same principles of vent dimensions and length I've built the new ones in Baltic Birch. They're a little deeper than your original design (10cm)
I got the local timber merchant to cut the 9mm birch ply to my sizes for the external panels and, not being blessed with routering skills I doubled up the baffle panels and used two different hole saws to make the driver cut outs so that this time I could recess the Alpairs
Taking earlier advice I've lightened up on the stuffing - it looks the same but it is more fluffed out.
There were a couple of voids with these dimensions so I stuffed them quite tight with the damping material.
Cable is Chord Odyssey soldered direct to the drivers with no phono sockets between drivers and amp.
The finish is beeswax. Have to say I'm pretty impressed with these speakers. Compared to the prototypes they are a touch more transparent all round and bass goes deeper, probably because of better construction, no leaks!
Anyway, thanks once more for posting this design, it's given me just what I needed for the hobby room.
Cheers, Ian
After the results with my chucked together prototype (3 pages back) I was sufficiently impressed to do a better build. Fractionally resized but keeping to the same principles of vent dimensions and length I've built the new ones in Baltic Birch. They're a little deeper than your original design (10cm)
I got the local timber merchant to cut the 9mm birch ply to my sizes for the external panels and, not being blessed with routering skills
I doubled up the baffle panels and used two different hole saws to make the driver cut outs so that this time I could recess the Alpairs
Taking earlier advice I've lightened up on the stuffing - it looks the same but it is more fluffed out.
There were a couple of voids with these dimensions so I stuffed them quite tight with the damping material.
Cable is Chord Odyssey soldered direct to the drivers with no phono sockets between drivers and amp.
The finish is beeswax. Have to say I'm pretty impressed with these speakers. Compared to the prototypes they are a touch more transparent all round and bass goes deeper, probably because of better construction, no leaks!
Anyway, thanks once more for posting this design, it's given me just what I needed for the hobby room.
Cheers, Ian
Thanks. Re wasted space, only the two vertical bits filled with wool in the pic above are voids. The horizontal part is the closed end of the MLTL or have I misunderstood what you mean?
Great job! Beautiful speakers and so glad they are living up to your expectations. Good idea to make a rectangular baffle - that will reduce the baffle diffraction effects and make it smoother. Making the drivers flush is what is helping the transparency. Your little bit of "wasted" space probably did not need any wool - filling with sand to give mass to the speaker could also have been done. Having that extra space is worth the improved response smoothness from having a rectangular baffle is a worthwhile trade.
Yes, that works but I think he wanted driver centrally mounted. Looks better and less baffle step loss for bass.
That's true, I did want the driver in the middle for aesthetic reasons and besides the void matches parts of my brain - at least it means I don't get too excited over trivia
Actually BP1 I like your design proportions and may try it one day so thanks for posting.
OK, I've had time to do some longer listening and on the whole these are quite superb speakers. Bass is more than adequate. Although not my normal fare, Inhaler by Hooverphonic has some serious deep synth bass and these little speakers render it remarkably well. Also surprising is the soundstage. Depending on the track of course but some sounds appear outside the speakers, left and right, Jennifer Warne's The Hunter for instance, and stage depth is quite remarkable considering the speakers' position against the wall. Fine detail is also resolved very well. For example the multi-layered vocals of Agnes Obel are beautifully separated.
However, extended listening has also brought out a mild but irritating problem. I do like female vocalists and I've noticed a lack of sweetness with these speakers. It's as if the artists have aged, voices have become a little thinner and a touch more strident. Sure, it adds to a sense of detail but loses out on warmth.
I've done a couple of things to see if they would help. I've lined the chamber immediately behind and surrounding the drivers with felt underlay which maybe had a tiny effect - it's easy to kid yourself with these things. Adding a bit more stuffing seems to have improved things but not a full cure.
Now, I admit freely I'm a novice at this so I don't really understand the theory or expected results of altering stuffing density so should I continue adding more or is this likely to affect other aspects which are currently spot on? The drivers themselves were run in properly and used for perhaps 300 hours but they have been idle for a few months so is there a likelihood they have stiffened up somewhat? The only other variable I can think of is the digital source.
Amp is a Ming Da Piccolo, single ended valves and source is a Vortexbox but rather than going through a Meridian Director DAC as in my main system it's sending it's signal via wifi to a Squeezebox Duet up to this system.
I think this minor problem is with my speakers but if anyone has an opinion I'd love to hear it.
Cheers, Ian
OK, I've had time to do some longer listening and on the whole these are quite superb speakers. Bass is more than adequate. Although not my normal fare, Inhaler by Hooverphonic has some serious deep synth bass and these little speakers render it remarkably well. Also surprising is the soundstage. Depending on the track of course but some sounds appear outside the speakers, left and right, Jennifer Warne's The Hunter for instance, and stage depth is quite remarkable considering the speakers' position against the wall. Fine detail is also resolved very well. For example the multi-layered vocals of Agnes Obel are beautifully separated.
However, extended listening has also brought out a mild but irritating problem. I do like female vocalists and I've noticed a lack of sweetness with these speakers. It's as if the artists have aged, voices have become a little thinner and a touch more strident. Sure, it adds to a sense of detail but loses out on warmth.
I've done a couple of things to see if they would help. I've lined the chamber immediately behind and surrounding the drivers with felt underlay which maybe had a tiny effect - it's easy to kid yourself with these things. Adding a bit more stuffing seems to have improved things but not a full cure.
Now, I admit freely I'm a novice at this so I don't really understand the theory or expected results of altering stuffing density so should I continue adding more or is this likely to affect other aspects which are currently spot on? The drivers themselves were run in properly and used for perhaps 300 hours but they have been idle for a few months so is there a likelihood they have stiffened up somewhat? The only other variable I can think of is the digital source.
Amp is a Ming Da Piccolo, single ended valves and source is a Vortexbox but rather than going through a Meridian Director DAC as in my main system it's sending it's signal via wifi to a Squeezebox Duet up to this system.
I think this minor problem is with my speakers but if anyone has an opinion I'd love to hear it.
Cheers, Ian
Measurements reveal that driver has some special voicing and some of it is same scheme as CHN70, unfortunate drivers datasheet present a vertical 120dB range and seems hard to read or useless.
xrk971 shared some nice data at comparison threads for small full rangers and A7 paper was present at round 3.
You asked if anyone has an opinion, well think in that data the HD peak 600-700Hz plus very unique voiced frq response and ringing IR is some the cause.
A7 paper FR & HD: (linked from http://www.diyaudio.com/forums/full...2in-4in-drivers-round-3-a-24.html#post4418888)
Compare to B80 from same thread:
A7 paper impulse response:
Compare to B80:
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As Byrtt has said, the sound signature of the A7P is not for everyone. A better driver that is a drop in fit would be the metal coned A7.3. It is smoother to be sure. Some EQ'ng might help so looking at the measured response that I made will give you some ideas where to apply EQ. Reduce the plateau from 3k to 5k and smooth out the dip at 6k.
Thanks for the info BYRTT. So if that is the case the Alpair 7p has a bit of a wobble smack in the middle of the female singing voice and that is what I'm hearing - seems odd to design a speaker that does that. Is is possible to smooth this out with the stuffing? I don't remember it being as obvious when I had the drivers in frugel horns but then I never used them in the current smaller room.
Out of interest I moved the speakers downstairs in the main listening room where I normally listen to Frugel Horn XLs with 10p drivers in them. It may be I have got used to the 10p drivers which to my ears have a smoother presentation but then the 7ps have a certain magic to them also. Anyway, in this setting, listening at around 16ft away instead of 10ft the little boxes did sound a bit smoother on female vocals so part of the issue is room matching. Out of interest I also played some vinyl through them, same Agnes Obel songs, and the 7p's sounded considerably smoother.
Out of interest I moved the speakers downstairs in the main listening room where I normally listen to Frugel Horn XLs with 10p drivers in them. It may be I have got used to the 10p drivers which to my ears have a smoother presentation but then the 7ps have a certain magic to them also. Anyway, in this setting, listening at around 16ft away instead of 10ft the little boxes did sound a bit smoother on female vocals so part of the issue is room matching. Out of interest I also played some vinyl through them, same Agnes Obel songs, and the 7p's sounded considerably smoother.
Sorry XRK, posting while you were replying. So are you saying there are no solutions re stuffing? I've only used EQ once with a mini-DSP when I was messing with my open baffles and to my ears it added more problems than it solved but then I do prefer analogue to digital and another layer of A/D then D/A didn't suit me - went for passive crossover in the end.
Cheers, Ian
The stuffing/padding behind driver is important and will help reduce the back reflections from coloring sound. But unfortunately, with the A7P, the signature of that plateau followed by the dip will not be resolvable with stuffing alone. You can EQ in software with a player like jriver - a great all around music station hub of your audio. Believe me, the fixes possible by EQ or DSP far outweigh any ADC-DAC or digital conversion "noise" you are concerned about. I would help if you had a mic and measured the response so you can see what you are getting. The response I got from the A7.3 in this MLTL is fairly flat with large peaks in the HF which the A7.3 is known for. Would you consider trying other drivers? I can retune the box for a B80 if you feel like giving that a go. It will be almost guaranteed to sound superior to the paper A7P. Or at least the A7.3, but of you are going to spend that kind of money, the B80 is a better driver from flat response, build quality, cleaner impulse, excellent waterfall.
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That driver does indeed have Qts suitable for a MLTL. It will be much smaller though as the Sd is quite a bit less than an A7. I will see what I can do - give me a few days.
I'd reluctantly have to agree with X on the paper vs metal on the A7- when used solo* although between the Alpair 10s, the difference / preference is harder for me to call.
* at the risk of sounding too subjective, the 7P seems less idiocyncratic when used in a bi-amped 2 way, and while computer based player is part of my music system, it doesn't easily accommodate EQ, so even casting my decades long aversion to that aside, it's not something I've been able to explore ar home. Whatever rough EQ Audyssey XT32 arrives at is pretty much what I live with
And yes, on shallow enlcosures with lighter weight FR driver cones, some absorption immediately behind the driver should probably be considered essential
* at the risk of sounding too subjective, the 7P seems less idiocyncratic when used in a bi-amped 2 way, and while computer based player is part of my music system, it doesn't easily accommodate EQ, so even casting my decades long aversion to that aside, it's not something I've been able to explore ar home. Whatever rough EQ Audyssey XT32 arrives at is pretty much what I live with
And yes, on shallow enlcosures with lighter weight FR driver cones, some absorption immediately behind the driver should probably be considered essential
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