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Alpair 6M for Cyburgs Needle / BR M.A. Design
Alpair 6M for Cyburgs Needle / BR M.A. Design
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Old 6th February 2018, 05:14 PM   #61
grahamgraham is offline grahamgraham  United Kingdom
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I like the sound of a big puffy mass...


OK, I will try on the weekend to remove the old wadding and insert newer fluffier masses. Tho, I wonder if it would be beneficial to start again with ply?

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The structure you want is no structure… one big puffy mass.

Here is what 40g of acoustastuff looks packaged/teased

Click the image to open in full size.

dave
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Old 6th February 2018, 05:32 PM   #62
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Don't look here for an argument against using decent Baltic Birch plywood. A trick of another designer of similarly configured enclosures - and I think Scott wouldn't mind saying one that's been around for decades - would be to make the rear panel removable on cleats to allow easy access to adjust amount & distribution of fill.

And even on something as compact as these, a little bracing never hurts
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Last edited by chrisb; 6th February 2018 at 05:35 PM.
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Old 6th February 2018, 05:43 PM   #63
grahamgraham is offline grahamgraham  United Kingdom
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I'm starting to regret my shortcuts!

If I add cleats surely I will change the cross-sectional area and volume of the design, tho?

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Don't look here for an argument against using decent Baltic Birch plywood. A trick of another designer of similarly configured enclosures - and I think Scott wouldn't mind saying one that's been around for decades - would be to make the rear panel removable on cleats to allow easy access to adjust amount & distribution of fill.

And even on something as compact as these, a little bracing never hurts
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Old 6th February 2018, 06:05 PM   #64
grahamgraham is offline grahamgraham  United Kingdom
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I just had a thought... (Danger zone)

If I jigsaw out a very straight rectangle from the rear I could use the cut out and mount it to another panel so it could fit back in being secured by screws around the edge. Poorly doodled image attached.

I could put foam tape on the seems.

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Originally Posted by chrisb View Post
Don't look here for an argument against using decent Baltic Birch plywood. A trick of another designer of similarly configured enclosures - and I think Scott wouldn't mind saying one that's been around for decades - would be to make the rear panel removable on cleats to allow easy access to adjust amount & distribution of fill.

And even on something as compact as these, a little bracing never hurts
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Old 6th February 2018, 06:49 PM   #65
chrisb is offline chrisb
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I don't think the slight decrease in total CSA / volume from adding cleats wouldn't be significant enough, but if concerned, your idea could certainly work. The cleats on Pensils above were 18mm square, and they also incorporated closed cell foam weatherstripping tape - not shown in the photo.
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Old 9th February 2018, 01:37 PM   #66
grahamgraham is offline grahamgraham  United Kingdom
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I have reassessed the fluffy mass and plumped for a fluffier filler. Hopefully once I have this in the issues will be solved.

I listened to the port very carefully with my ear to it and I could hear clear vocals. I guessing that once I get the stuffing right it will have a knock on effect to the other frequencies?

When listening to TV with them voices are very boxy and resonant with a dip somewhere in the upper mid (?).
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Old 9th February 2018, 05:13 PM   #67
planet10 is offline planet10  Canada
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Alpair 6M for Cyburgs Needle / BR M.A. Design
The pipe produces a ripple train. You want to preserve the lowest one and get rid of the rest. The restricted terminus, driver off-set and damping are all tools to create the low pass filter at the terminus.

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Old 20th February 2018, 12:04 PM   #68
grahamgraham is offline grahamgraham  United Kingdom
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Thanks, it's great to be able to see and hear it all come together and know why!

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The pipe produces a ripple train. You want to preserve the lowest one and get rid of the rest. The restricted terminus, driver off-set and damping are all tools to create the low pass filter at the terminus.

dave
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Old 20th February 2018, 12:25 PM   #69
grahamgraham is offline grahamgraham  United Kingdom
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Right!

I have semi finished them! I rounded over the vertical corners, installed proper stuffing and painted them. A lovely peach colour to match our pastel front room.

The stuffing was the issue, they sound completely different and tonnes better. Though, I can still hear a little bit of mid frequency coming through the vent. I added 10-15g of stuffing to see if it would help but it is the same. I don't know if this is actually an issue as I have them crossed over at around 100hz with two sealed Tang Band 6.5" subs using a Minidsp balanced unit and they sound great with this sub reinforncement. I alter the crossover frequency a fair bit and I have set them as low as 80hz with no issues.

I have a question regarding the top end of the FR. Somethign was missing from the sound so I tinkered with Minidsp and ended up boosting at around 7.5khz at 2db with a Q of 0.5. I've attached a wonky shot of the EQ. Ignore the low end, I'm taming room modes. Is this common for this driver? Do others have experience with boost treble to make it sound right?

The drivers are 1mm proud of the recess, is this an issue? Also, does the slim cabinet and roundover edges have any impact on FR?

I am jolly pleased with the outcome so far, thanks to Scott and Dave for this design, very happy.

I am thinking of building something out of the Alpair 10p, maybe a 5.1 set up with this pair as rears. Is there a similar design that is tall and slim that would work? The accidental MLTL idea could be an idea but if I just design a tall bass reflex cabinet and port it as normal will I encounter more issues than benefits if this does not take in to account the quarterwave physics?

Really enjoying full range drivers at the moment!!!
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Old 20th February 2018, 05:13 PM   #70
chrisb is offline chrisb
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The A10P and.3 have been around long enough that there's plethora of proven enclosures for them - I've heard & built probably half a dozen different designs. My personal favorite for sonic performance is the FHXL, but for simplicity of build and smaller footprint, the Pensil* is definitely worth consideration - I'm currently using a pair myself as front mains in a 7.1 system with all MA drivers.

*As with all of Scott Lindgren's designs, there's nothing "accidental" about the final published art.
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