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SEAL

shaan

Well-Known Member
Joined
Oct 5, 2012
Messages
230
Likes
364
Points
63
Location
Kolkata
#1
Hi fellas.

Approaching the finishing of a year-long experimental project, a 100% sealed 2.2 speaker system.

Here is a snap showing the thing(s) along with my ever-so-naked-never-inside-a-cabinet amplifier channels (two V4s for the fullranges and two V4Hs for subwoofers) driven from my old and faithful diy 24dB/octave 2.1 active crossover (crossed at 150Hz). For the time being, both sub channels are fed the same 'point-one' mixed LF signal from the xover. A 2.2 crossover with linkwitz transform for LF is cooking so this handicap is not meant for long.

IMG_20180529_164959_HHT~2.jpg

It consists of two 8" FR drivers bought from diyaudiocart in August last year (Boston Acoustics HiQ, 8ohm, 93dB) and two 10" LF drivers ordered and made locally about 7 years ago (no brand, 4ohm, sensitivity unknown). That's right the LF drivers were sleeping for almost a decade. FR power 25WRMS each and Subs 200WRMS each.

Cabinet material is 3/4" marine ply for all four boxes. All boxes braced internally and stuffed with polyfill (IME trickiest parts of the whole project). FR box walls internally lined with coir fiber on rubber base. Subwoofers have no internal wall lining. All walls are joined by 2" galvanized nails (3 per edge) with sawdust+fevicol paste as seal. After walls were fixed, all inside edges and corners were manually re-sealed with the aformentioned paste and left to dry for a couple days. Drivers are mounted using typical t-nuts and bolts. A week ago the FR cabinets received steel feet from diyaudiocart, subs will get the same in late June after they have been coated with black matte-finish sunmica as the FRs. The FR drivers are also scheduled to get a pair of phase plugs soon (probably wooden) as I realized they benefit greatly from it. The grill frames will be made in mid-June as I plan to get a router by then; a little more close to perfect circles cannot be achieved by a jigsaw.

All the drivers had those ugly looking rubber gaskets in front of them. I carefully cut and removed all of those abominations; now they all look "imported". :p

The FR boxes weigh ~24Kg each and the sub boxes ~28Kg each, with driver installed. The bracing inside the sub uses the same ply but the ones inside the FRs are teak beams with 2 square-inch cross section, making them almlost as heavy as the subwoofer cabinets. There are some excess length of front wall in the sub cabinets protruding in all four directions, guess the router will help trim those properly.

This is it so far... more will follow soon.

FAQ- (you can skip this section)

q. Does it sing already?
a. Yes, after some modification done in the low-pass section of the crossover to make it compensate for subwoofer frequency response. Sealed subs, you know, are weird despite their apparent simplicity.

q. How does it sound?
a. GRAND! 25Hz to 18KHz no problem. Has touch, has power.

q. Wow! What is your next project?
a. Reinforcing the doors and windows.

t.b.c.
cheers
shaan
 
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Joined
May 17, 2014
Messages
85
Likes
9
Points
8
Location
chennai
#2
Hi fellas.

Approaching the finishing of a year-long experimental project, a 100% sealed 2.2 speaker system.

Here is a snap showing the thing(s) along with my ever-so-naked-never-inside-a-cabinet amplifier channels (two V4s for the fullranges and two V4Hs for subwoofers) driven from my old and faithful diy 24dB/octave 2.1 active crossover (crossed at 150Hz). For the time being, both sub channels are fed the same 'point-one' mixed LF signal from the xover. A 2.2 crossover with linkwitz transform for LF is cooking so this handicap is not meant for long.


It consists of two 8" FR drivers bought from diyaudiocart in August last year (Boston Acoustics HiQ, 8ohm, 93dB) and two 10" LF drivers ordered and made locally about 7 years ago (no brand, 4ohm, sensitivity unknown). That's right the LF drivers were sleeping for almost a decade. FR power 25WRMS each and Subs 200WRMS each.

Cabinet material is 3/4" marine ply for all four boxes. All boxes braced internally and stuffed with polyfill (IME trickiest parts of the whole project). FR box walls internally lined with coir fiber on rubber base. Subwoofers have no internal wall lining. All walls are joined by 2" galvanized nails (3 per edge) with sawdust+fevicol paste as seal. After walls were fixed, all inside edges and corners were manually re-sealed with the aformentioned paste and left to dry for a couple days. Drivers are mounted using typical t-nuts and bolts. A week ago the FR cabinets received steel feet from diyaudiocart, subs will get the same in late June after they have been coated with black matte-finish sunmica as the FRs. The FR drivers are also scheduled to get a pair of phase plugs soon (probably wooden) as I realized they benefit greatly from it. The grill frames will be made in mid-June as I plan to get a router by then; a little more close to perfect circles cannot be achieved by a jigsaw.

All the drivers had those ugly looking rubber gaskets in front of them. I carefully cut and removed all of those abominations; now they all look "imported". :p

The FR boxes weigh ~24Kg each and the sub boxes ~28Kg each, with driver installed. The bracing inside the sub uses the same ply but the ones inside the FRs are teak beams with 2 square-inch cross section, making them almlost as heavy as the subwoofer cabinets. There are some excess length of front wall in the sub cabinets protruding in all four directions, guess the router will help trim those properly.

This is it so far... more will follow soon.

FAQ- (you can skip this section)

q. Does it sing already?
a. Yes, after some modification done in the low-pass section of the crossover to make it compensate for subwoofer frequency response. Sealed subs, you know, are weird despite their apparent simplicity.

q. How does it sound?
a. GRAND! 25Hz to 18KHz no problem. Has touch, has power.

q. Wow! What is your next project?
a. Reinforcing the doors and windows.

t.b.c.
cheers
shaan
Very neat.
 

shaan

Well-Known Member
Joined
Oct 5, 2012
Messages
230
Likes
364
Points
63
Location
Kolkata
#6
Thankyu! :)

This is an excellent DIY Shaan. Boston Acoustics HiQ has got a great mids. Enjoy.
Thanks. Yes the the BA drivers do indeed have killer mids.

Your source ?
What a great project, congrats shaan. Can you share some light on the amplifiers and the source?
The amps are lateral mosfet based class ab amplifiers, called PeeCeeBee. The FRs are being driven with the 50w/8r version (V4 Rev2) and the subs with the 250w/4r version (V4H).

Source are my PC and Mi A1 phone. Material format mostly MP3 320 and FLAC.

This is great stuff Shaan.

Congratulations..!!
Thanks mate! :cool:
Cheers
 

sdurani

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Joined
Jun 29, 2011
Messages
731
Likes
359
Points
63
Location
US
#9
One of the advantages of filtering the bass to subwoofers is that you get to place the subs where they give best bass reproduction in your room while placing the speakers where they give best soundstage & imaging.

With that in mind, consider spreading your speakers wider apart to give you a larger soundstage. It won't affect the bass because you won't need to move the subwoofers. Can't do that with large floorstanding speakers.
 

shaan

Well-Known Member
Joined
Oct 5, 2012
Messages
230
Likes
364
Points
63
Location
Kolkata
#10
One of the advantages of filtering the bass to subwoofers is that you get to place the subs where they give best bass reproduction in your room while placing the speakers where they give best soundstage & imaging.

With that in mind, consider spreading your speakers wider apart to give you a larger soundstage. It won't affect the bass because you won't need to move the subwoofers. Can't do that with large floorstanding speakers.
Yes I do listen in that config and have also seen a few other people who use active crossover do the same. Works perfectly for the best 3D presentation.

BTW, these are not the last sealed subs in the line. Targeting a pair based on Eminence Alpha 15A in the coming months! I love its awfully large diaphragm and insane sensitivity. Thinking of pairing them with a proportional mismatch, the Dayton RS100-8. :D
 
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shaan

Well-Known Member
Joined
Oct 5, 2012
Messages
230
Likes
364
Points
63
Location
Kolkata
#19
Getting Old Bro ...;)
Indeed sirjee!

What hurts is when younger listeners come to audition my speakers and say they can hear stuff above 15K in my fullranges clearly and I have to nod and act as if I can hear that too.

Who cares, my phone can hear 20KHz. I only need to know whether the information is there or not. And it clearly is!
 

diyaudio

Active Member
Joined
Apr 6, 2018
Messages
103
Likes
80
Points
28
Location
India
#20
Young people can hear till about 18khz, 20khz would be very rare to find. 10khz to 20khz is just one octave, there is not much to fret about whether one's higher limit is 14khz or 18khz. We are told 20khz is normal hearing and everyone believes that they can hear it. ;)

I cant hear over 14khz and I dont feel I miss anything.
 
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