What kind of alignment is that? Compared with the vented alignments in the books I've got, the box is way big. Can the next gen from ProAc (D25) be classified as a MLTL?
http://www.audiophile.com.au/proac_specs/d25.html
How about the 2.5 with the port in the middle?
Here's a quote from the page about the D25:
http://www.audiophile.com.au/proac_specs/d25.html
How about the 2.5 with the port in the middle?
Here's a quote from the page about the D25:
sreten said:
A quick calculation indicated around 36 litres internal volume.
Another quick calculation indicated external volume is 57 litres.
What does your book tell you it should be ?
sreten.
Are your "quick calculations" figuring what the volume of the DIY cabinets actually are, based on the drawings, or are you calculating what some alignment tables tell you the volume of a ported system should be, based on the T/S parameters? -- or what? I am baffled (cough). Go ahead and squander a few words. Typing calms the soul.
The original question was, what kind of alignment is it? Do you know?
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Joined 2003
I don't know for sure, but I don't think the D25 is a TL.
I *suspect* it would be a QB3 vented box, albeit with the port facing the floor. A bit like subwoofers with downward facing ports.
However the Response 2.5 was a vented box. The internal volume is 34L, with port 75mm (internal diameter) x 140mm long.
I *suspect* it would be a QB3 vented box, albeit with the port facing the floor. A bit like subwoofers with downward facing ports.
However the Response 2.5 was a vented box. The internal volume is 34L, with port 75mm (internal diameter) x 140mm long.
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Joined 2003
yep one of the ways to extend the bass response of the 2.5 clones is to lengthen the port. gives deeper bass.
the 2.5 and clone has a port configuation that, as sreten correctly points out, gives bass lift from 100Hz to 50Hz, making it sound punchy, and perhaps the illusion of more bass than it really has. - The first time you listen to these speakers you're staring at what seems to be a single 6.5" woofer, playing 8" or 10" levels of bass! You can definitely leave the subwoofer off with this thing!
It's hard to say whether it's right or wrong but I look at it as a pro or con-
This configuations allows you to keep it clear of the front wall (1 metre minimum) thus minimizing early reflections from ruining clarity and imaging, whilst allowing a "muscular bass" presentation.
One of the flat (sretens' last post) or overdamped responses ( sreten's earlier red line alignment) may sound better if you find the bass a bit a little too prominent. I think this may also be of benefit if space or spouse dictates that the speaker must sit against a wall (allows for room gain additive effects).
the 2.5 and clone has a port configuation that, as sreten correctly points out, gives bass lift from 100Hz to 50Hz, making it sound punchy, and perhaps the illusion of more bass than it really has. - The first time you listen to these speakers you're staring at what seems to be a single 6.5" woofer, playing 8" or 10" levels of bass! You can definitely leave the subwoofer off with this thing!
It's hard to say whether it's right or wrong but I look at it as a pro or con-
This configuations allows you to keep it clear of the front wall (1 metre minimum) thus minimizing early reflections from ruining clarity and imaging, whilst allowing a "muscular bass" presentation.
One of the flat (sretens' last post) or overdamped responses ( sreten's earlier red line alignment) may sound better if you find the bass a bit a little too prominent. I think this may also be of benefit if space or spouse dictates that the speaker must sit against a wall (allows for room gain additive effects).
The only downside of a longer port (as I have chosen, to reduce the irritating Proac bass bloom) is increased cone excursion for the same spl at low frequency.
The correct stuffing - low density dacron - increases the apparent box size as seen by the driver. I'm not sure if Sreten's simulations take this into account.
It certainly is not easy to get clean tight and deep bass out of the Clone. Straws in the ports improves the timing but gives slightly weak bass.
I reckon Proac left themselves a pretty easy task of making the bass of the D25 better than the R2.5.
The correct stuffing - low density dacron - increases the apparent box size as seen by the driver. I'm not sure if Sreten's simulations take this into account.
It certainly is not easy to get clean tight and deep bass out of the Clone. Straws in the ports improves the timing but gives slightly weak bass.
I reckon Proac left themselves a pretty easy task of making the bass of the D25 better than the R2.5.
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Joined 2003
I ran WinISD which seemed to suggest that that the driver is also suited for a sealed alignment.
So I tried stuffing the ports with T shirts. After a short listen I felt that this reduced the bass lump, but made the midrange sound a bit closed in.
The bass is definitely a bit on the generous size- on the majority of my program material I found it to be of desirable. I became acutely aware of the issue after listening to- Eric Clapton's Unplugged and Harry Connick Jr's Only You. Level seemed just too high, and pitch definition could be better.
The back of my clones are at least 1 metre from the front wall too...
To keep it in perspective though I think tight and deep bass out of a vented box is always difficult, not just the clones. I've heard a few better, but a lot worse. Certainly far from the "one-note bass" like most HT subwoofers out there.
So I tried stuffing the ports with T shirts. After a short listen I felt that this reduced the bass lump, but made the midrange sound a bit closed in.
The bass is definitely a bit on the generous size- on the majority of my program material I found it to be of desirable. I became acutely aware of the issue after listening to- Eric Clapton's Unplugged and Harry Connick Jr's Only You. Level seemed just too high, and pitch definition could be better.
The back of my clones are at least 1 metre from the front wall too...
To keep it in perspective though I think tight and deep bass out of a vented box is always difficult, not just the clones. I've heard a few better, but a lot worse. Certainly far from the "one-note bass" like most HT subwoofers out there.
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