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I've been so distracted with other things that I haven't tried it with the back on yet. I have a lot of business travel at the present time and don't expect to get around to more experiments until late December.
I am happy with the quantity of bass output from the open back but the quality of it isn't quite right - it's a little spongy and the freq response doesn't sound flat. However, this doesn't concern me, I don't think it's a fault of the driver or my future plans for this enclosure. I think it's mostly a limitation of this particular tube amplifier along with poor room positioning and the wrong stuffing.
I fully expect the Boffle solution and a closed back approach both to work very well indeed and it will be a matter of taste as to which I prefer.
All in all, I don't see (or hear) any reason why you should be cautious about buying a pair of these drivers.
As for enclosure - well I recommend the box I built.
I don't recommend Open Baffle - not because I don't think OB is good, but I don't see it as the best choice for the AN15. The reasons are - this driver is not dipole, the frequency response at the front and back are different, not least because at the front you have a whizzer cone. I also believe you can't have the driver too near the floor because then the high frequencies are too low relative to your listening position, yet placing the driver at ear height will mean inadequate bass. This forces you to add another driver. And for me, this negates the benefits and purpose of choosing the AN15 in the first place. An OB in my view is better served with a 4" to 6" full range and supported by a 15" woofer.
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UPDATE
I've been using the AN15 in the box, open backed, for a few months now. The amplifier has been my Cellini SET.
I have found a few things so far - the bass goes reasonably deep but it's a bit laid-back and it sounds as if there are some holes in the mid bass response, probably a consequence of the open backed box that I'd like to fix at some point. The treble is not as clean as I would like - this speaker is big and relies on a whizzer and a phase plug. It isn't well suited to near field, you hear a lot of stuff that doesn't sound right with your head up near the driver. You need to be many feet away.
Yesterday I switched out the tube amp for my Bryston BP60 and pulled the speaker box further out from the walls. This made a nice change. It's clearly a lot more dynamic, the bass is punchy and deep, the mids are precise and the treble is cleaner. There's still some of that open baffle suck out in the mid bass somewhere.
Clearly I have been hearing a number of limitations of my old SET amplifier (my first ever tube build and not super hi-fi). There is still some directionality in the treble and I think some peakiness (as evidenced on the data sheet) that I will address later. But my faith in this driver has been strengthened by the amplifier swap. I have never heard a full range produce such a clear and dynamic output that truly goes from deep bass to the treble. I shall have to invest some more time and effort into this speaker.
I've been using the AN15 in the box, open backed, for a few months now. The amplifier has been my Cellini SET.
I have found a few things so far - the bass goes reasonably deep but it's a bit laid-back and it sounds as if there are some holes in the mid bass response, probably a consequence of the open backed box that I'd like to fix at some point. The treble is not as clean as I would like - this speaker is big and relies on a whizzer and a phase plug. It isn't well suited to near field, you hear a lot of stuff that doesn't sound right with your head up near the driver. You need to be many feet away.
Yesterday I switched out the tube amp for my Bryston BP60 and pulled the speaker box further out from the walls. This made a nice change. It's clearly a lot more dynamic, the bass is punchy and deep, the mids are precise and the treble is cleaner. There's still some of that open baffle suck out in the mid bass somewhere.
Clearly I have been hearing a number of limitations of my old SET amplifier (my first ever tube build and not super hi-fi). There is still some directionality in the treble and I think some peakiness (as evidenced on the data sheet) that I will address later. But my faith in this driver has been strengthened by the amplifier swap. I have never heard a full range produce such a clear and dynamic output that truly goes from deep bass to the treble. I shall have to invest some more time and effort into this speaker.
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I have not done that yet - I'm embarassed to say. I have prepared a back piece with holes drilled but I need to buy some bolts. There are T-nuts fitted at the back of the box to accommodate it. I also need some lining material, some felt would be good. It just hasn't been a priority (yet).
You don't have to scroll back in the thread very far to find some; post 274 shows a finished picture.
The box is 2 feet deep.
I'll review post 270 to today.
Nice box.
2' deep ?
Well, based on simple math, 1129/4' (that's where the front wave will meet the back and cause a dip, I consider a driver to start canceling at its closest edge) = dip at 280hz, but a peak around 140hz (+3db to +6db, that's where the front is 1/4 wavelength out of phase, thusly adding). Have it close to the back wall helps add the bass too.
Yea, it is doesn't go way low, but the peak really adds a loudness hump (always nice), especially to speakers in boxes without baffle step, and our lower listening levels to prevent garbling the midrange.
I'd always said you (anyone = you) need 2' minimum distance from the front of the driver to the back.
Classic theory says an open baffle with wings (straight back), the wings should not be more than 1/3 or 1/4 as long as the front width (for standing wave resonances). I know my large folded baffle (wings on hinges), it was easy to play, but having them parallel and a foam box around the backside, I didn't hear any problems, even folded back to make a triangle shaped box.
Too bad, I think you should try a 10 band eq to play with the response, and I'd imagine the dispersion is limited, thusly the reflected field would see to have less highs.
Norman
Nice box.
2' deep ?
Well, based on simple math, 1129/4' (that's where the front wave will meet the back and cause a dip, I consider a driver to start canceling at its closest edge) = dip at 280hz, but a peak around 140hz (+3db to +6db, that's where the front is 1/4 wavelength out of phase, thusly adding). Have it close to the back wall helps add the bass too.
Yea, it is doesn't go way low, but the peak really adds a loudness hump (always nice), especially to speakers in boxes without baffle step, and our lower listening levels to prevent garbling the midrange.
I'd always said you (anyone = you) need 2' minimum distance from the front of the driver to the back.
Classic theory says an open baffle with wings (straight back), the wings should not be more than 1/3 or 1/4 as long as the front width (for standing wave resonances). I know my large folded baffle (wings on hinges), it was easy to play, but having them parallel and a foam box around the backside, I didn't hear any problems, even folded back to make a triangle shaped box.
Too bad, I think you should try a 10 band eq to play with the response, and I'd imagine the dispersion is limited, thusly the reflected field would see to have less highs.
Norman
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I don't have EQ on hand at the present time (could change in the future) but I might try playing with some simple analogue solutions first - and try also a closed box. I don't have plans to try it vented, the box wasn't dimensioned for a vented enclosure and I expect it will go deep enough based on a closed box if I wanted to go that route.
Norman - have you ever looked at the Boffle concept ?
Norman - have you ever looked at the Boffle concept ?
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How large did this enclosure end-up being, was it the 13.6c.f?
Based on the published specs, looks like 13.6c.f sealed with light stuffing would be very good (Qtc~0.75, f3~42Hz). I would not go below 6c.f (Qtc~1.0), would use somewhat heavier stuffing (~1c.f increase in apparent Vb) and would probably make this aperiodic (Ql=2~3) to bring Qtc down and still have reasonable bass output (f3~60Hz) without ruining it for high-impedance amplifiers.
IG
Based on the published specs, looks like 13.6c.f sealed with light stuffing would be very good (Qtc~0.75, f3~42Hz). I would not go below 6c.f (Qtc~1.0), would use somewhat heavier stuffing (~1c.f increase in apparent Vb) and would probably make this aperiodic (Ql=2~3) to bring Qtc down and still have reasonable bass output (f3~60Hz) without ruining it for high-impedance amplifiers.
IG
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Yes, it ended up full sized. Probably it's a bit larger than what I forecasted. The idea is to ensure it's large enough that 'aperiodic' is not required.
And I agree, sealed should be very good. This was my original design intent. But open back boxes are also of interest so that is why I'm exploring both options.
And I agree, sealed should be very good. This was my original design intent. But open back boxes are also of interest so that is why I'm exploring both options.
foam ? like the grey finger stuf at parts express, but sandwiched together so it is thicker.
Wow, that'd be a big, big box. The qts and the vas makes it like the fifteen inch "woofers of old" needing 15ft3 for porteds, eek.
Found this on low bass coming from a too small open baffle.
http://www.diyaudio.com/forums/multi-way/112796-sideways-dipole-bass-3.html#post3504788
post #24
"If wavelength become larger (say >1m for "small rooms"), the dipole no longer shows its figure 8, but increasingly feeds the inidividual room modes only. The bass you will get at a certain position in the room will be the bass which the room modes produce there. That is the same procedure as for other bass loudspeakers, but with a somewhat different mode excitation."
Explains why your 2' deep open baffle seems to have some low bass.
I like your box design.
It one of the only options for that driver (in my opinion).
interesting........................
Norman
Wow, that'd be a big, big box. The qts and the vas makes it like the fifteen inch "woofers of old" needing 15ft3 for porteds, eek.
Found this on low bass coming from a too small open baffle.
http://www.diyaudio.com/forums/multi-way/112796-sideways-dipole-bass-3.html#post3504788
post #24
"If wavelength become larger (say >1m for "small rooms"), the dipole no longer shows its figure 8, but increasingly feeds the inidividual room modes only. The bass you will get at a certain position in the room will be the bass which the room modes produce there. That is the same procedure as for other bass loudspeakers, but with a somewhat different mode excitation."
Explains why your 2' deep open baffle seems to have some low bass.
I like your box design.
It one of the only options for that driver (in my opinion).
interesting........................
Norman
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Perhaps you should try to dampen the backwave like this http://www.diyaudio.com/forums/full-range/162827-mpl-26.html#post3410615
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I have put some old clothes in the back of the box to absorb the high frequencies - a poor mans Boffle but I need to do some more experiments. The day job keeps me a bit occupied but perhaps this weekend will yield some time to play.
I don't think the uneven bass response will be acceptable if I keep it open backed, some kind of EQ will be needed. It might be possible to implement a line level passive EQ, or perhaps I should go 'modern' and get one of those miniDSP gadgets to play with ?
I don't think the uneven bass response will be acceptable if I keep it open backed, some kind of EQ will be needed. It might be possible to implement a line level passive EQ, or perhaps I should go 'modern' and get one of those miniDSP gadgets to play with ?
MiniDSP is pretty great. It might matter to some that they can't say they listen 100% analog anymore, but it certainly does not ruin listening to vinyl for me; I don't think I could tell if I didn't know. In your case though, I'd try to find the best acoustic solution before going with electrical corrections. Since you went for the full-size build (I assume 13.6cu.f), you already have a nice medium sealed Qtc and might only need some lining on the walls. Model shows f3 in the mid 40ies, not too shabby. 
IG
IG
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I will be working on a non-DSP signal chain for now, for sure.
Interesting - I didn't know there was a new hi-end speaker manufacturer in Canada using the Audio Nirvana (I think the largest size is 12" though): RJH Audio Extremely Efficient Full Range Single Point Source Loudspeakers for the Discerning Listener.
Interesting - I didn't know there was a new hi-end speaker manufacturer in Canada using the Audio Nirvana (I think the largest size is 12" though): RJH Audio Extremely Efficient Full Range Single Point Source Loudspeakers for the Discerning Listener.
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Well I actually put the back on the box for the first time today. I fit some batting on some of the internal surfaces and took out my kids old clothes before I bolted on the back.
I also had to fit a terminal cup.
My tube amp isn't sounding so good these days, maybe the tube is getting old. So I popped in my Bryston BP60 to listen to the top 40.
Strange thing - seems to me that there is less bass. The sound is very clean but the balance is tilted up. The back may have to come back off...
I also had to fit a terminal cup.
My tube amp isn't sounding so good these days, maybe the tube is getting old. So I popped in my Bryston BP60 to listen to the top 40.
Strange thing - seems to me that there is less bass. The sound is very clean but the balance is tilted up. The back may have to come back off...
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if they generally meet spec then one should play in a Karlson 18 the size of the Cetec-Gauss 5181 cabinet - it needs a stronger motor to do best in K15 but would probably sound pretty good in one
5181 plan - the rectangular indications on the sides were pockets for carrying handles. It probably would not hurt to open up the starting gap a bit
http://img72.imageshack.us/img72/825/gaussbracing.jpg
5181 plan - the rectangular indications on the sides were pockets for carrying handles. It probably would not hurt to open up the starting gap a bit
http://img72.imageshack.us/img72/825/gaussbracing.jpg
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