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-   -   Centre Speaker using Alpair 10 and some limitations (http://www.diyaudio.com/forums/markaudio/203542-centre-speaker-using-alpair-10-some-limitations.html)

zanlation 1st January 2012 09:31 AM

Centre Speaker using Alpair 10 and some limitations
 
I am building a set of L/R and centre speakers for my parents. They didn't have a large budget, so I was keen on building them something decent. I thought I could also veneer it to match their furniture.

I ordered 3 Alpair 10s and was planning on building three Classic GR Mar-ken 10.2s. After further conversions with my parents my Mum was very keen on putting the speaker into the AV component of their TV cabinet. The problem I now have is that the height of the AV component is only 200mm, and the width of the Alpair is 160mm (138mm for the back of the driver).

I modified the mar-ken design so the cabinet was 190 (h) x 350 (w) x 200 (l). Using 18mm MDF, this leaves only 7.5mm each side of the driver from the side panel. Could this be an issue? Anyone have ideas of what I could do?

planet10 1st January 2012 07:56 PM

Drawing of proposed?

dave

zanlation 1st January 2012 09:40 PM

I have attached a drawing of the modified design.

http://www.zanlation.com/images/GR10_Centre_Design.png

planet10 2nd January 2012 06:04 AM

Without checking anything else, the vent is too narrow by 2 material thicknesses.

Here is the "official" skinny as possible version:
http://p10hifi.net/tlinespeakers/FAL...0g2-190611.pdf

If you need to maintain the 190 width, you will need to increase vent height to maintain vent cross-section -- or shorten the vent by the appropriate amount. If you are using 18mm material then vent height needs to go to 18.5mm.

The proximity of the walls will likely be heard as a honkiness or cupped sound in vocals.

dave

zanlation 3rd January 2012 07:27 AM

I will probably need to look for a smaller driver. would a single or dual Chr-70 suit the alpair 10?

planet10 3rd January 2012 07:29 AM

An alpair 7 would be the closest timbre match to A10.2 mains. CGR goes from 13 litre to 9 litre. I may have a 10 litre A10.2 box (i do have one that size for A12)

dave

zanlation 3rd January 2012 10:29 AM

Dave, thank you for your help. i would be interested in the 10l box.

chrisb 3rd January 2012 05:42 PM

Quote:

Originally Posted by planet10 (Post 2844542)
An alpair 7 would be the closest timbre match to A10.2 mains. CGR goes from 13 litre to 9 litre. I may have a 10 litre A10.2 box (i do have one that size for A12)

dave

I have a Alp7 (1st Gen) in one of Dave's wide stretched centre cabinets - it certainly works very well. Since most HT rigs will XO the center above 80Hz, I think its reduced LF capability compared to the 10.2 is moot, and AFAIC the 7.3 does things in the critical vocal band with more refinement, inner/low level detail and depth than the larger drivers.

Of course in a really large home theater with 3 rows of seating, popcorn machines and wet bars, the smaller FR drivers might not suffice, but in a more modest venue (under 400ft^2) the 10.2 & 7.3 combo & A6M for surrounds would be very nice.

planet10 3rd January 2012 06:28 PM

1 Attachment(s)
Quote:

Originally Posted by zanlation (Post 2844683)
Dave, thank you for your help. i would be interested in the 10l box.

I looked in my drawings... i have a 10 litre sealed box... Q isbutterworth and F3 is on the order of 80 Hz, almost perfect for a centre channel. I would be hesitant to make the front any smaller than it currently is.

One could get 6 mm by moving to 15mm, or with added bracing get 12mm by using 12mm panels.

dave

zanlation 4th January 2012 03:25 AM

If I used 12mm plywood panels and bracing instead of MDF would that give sufficient strength?


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