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How to "tighten" the bass of MISSION m34i floorstanders

Luxman Amplifiers India

trittya

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Greetings ALL
This thread is in response to a query to the said effect by FMs Bluu and Inderbir here

http://www.hifivision.com/sale-owner/17103-mission-speakers-denon-avr-3.html

Unknown to many, the mission m series of floor-standers have a back-loaded cavity at the bottom of the speakers. This is meant to be filled with sand or an alternate material for weighing down the speaker with an aim to cut out the 'boom' in the bass and lo-mid frequencies. It does go a long way towards serving the intended purpose.

The sand(approx 9-10 kgs or more) must not be 'gravelish' and coarse but fine and comprising of fine near-round granules. Riverine white/silver sand with minimum (flaky & shiny) silica content is most preferred. Nevertheless, it still has to be washed thru a very fine steel sieve to make the powdery sand-dust flow away.

Dry the sand for a day in bright sunlight by spreading it on an old bed-sheet or the like.

Roast the dried sand in an open cast iron 'KADAHI'/'WOK' measuring at least 2 ft in dia.

Keep stirring and turning the sand till uniformly hot.

Test heat of sand by throwing in a maize seed. If it pops and turns to a popcorn flake, its just right but dont take it off just yet. Let the sand roast for another 20 min, turning it over occasionally. Be careful, that sand is worse than 'red-hot'.

Let the sand cool down naturally, be patient, stir occasionally to aid cooling. Then let it rest after warm to cool down totally.

Add about one large peg each (60 ml each) of concentrated fungicidal liquid to prevent moulding/fungal growth.

Stir fungicide well into sand, if need be, add a wee bit more.

Let the fungicide dry completely, allowing the smell to subside substantially.

Make you spkr lie face down, dont remove the cloth grilles and do ensure that you prop the face on a couple of soft pillows or the like.
Make sure spkr is fully horizontal.

Remove plastic cover of cavity below the port on the rear.

Fill in about 1.5' - 2" of sand, tapping gently on the cabinet sides with the heels of your palms to make the sand settle.

Throw in a small handful of air-gun pellets(preferably the spike-tipped double-head ones)
Do spread the uniformly over the sand.
Pour in another 1.5' - 2" layer of sand and repeat the pellet routine.

Be patient and keep tapping the spkr cabinet gently all through.
Repeat above process till u reach the top with the cabinet empty enough just to let the cover fit in place. Throw in another handful of lead pellets before putting the lid back on.
Seal the lid with silicone caulk/ sealant(turns to silicone rubber on contact with air and can easily be peeled off).
Place some old heavy books over the lid to ensure sealing. Leave for 24 hrs before making spkr upright.
Repeat with other speakers.
Glasswool and lead pellets is another option.
Will talk more on that after hearing from you guys.
Hope this helps.
Regards
 
Last edited:

Bluu

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Thank you trittya! Very nice explanation. It is much more work than I expected. However, I'm glad that Kittu has to do all this work and not me :)
 

captrajesh

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Good explanation Trittya. BTW, would adding silica gel in addition to what you have suggested (to eliminate moisture builtup) makes sense?
 

Kittu

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Very nicely explained trittya, as bluu mentioned it was much work than expected. I just read online simply poring the baked sand will do the job..

I might loosen my ears a bit and feel the bass is tight for now. ;)
 

denom

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:D quite a bit of 'Cooking', 'Stirring', "60 ml", 'Patting' involved :p:D:eek:hyeah:;)

Jokes apart, excellent step by step explanation provided in easy to understand language, good job Sirji !!! Kindly keep providing such tips in future too for the benefit of us HFV'ians :)
 

denom

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Very nicely explained trittya, as bluu mentioned it was much work than expected. I just read online simply poring the baked sand will do the job..

I might loosen my ears a bit and feel the bass is tight for now. ;)
:D much like using them expensive 'audiophile' cables eh??? Only here you don't buy or do anything!!! :eek:hyeah:
 

denom

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ROFL!

Trittya - What about removing the sand? I suppose it will be nightmare to pour the sand out. Imagine the mess!
That I hope to learn about in the second lesson from Prof 'Trittya' :p
 

gobble

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ROFL!

Trittya - What about removing the sand? I suppose it will be nightmare to pour the sand out. Imagine the mess!
Yep. Isn't there a possibility of using sand bags?

Tip: For extended highs try a windbag ... :rolleyes:

--G
 

ash147

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rightly said.how about sand bags ? one can insert a plastic bag,the thin one given by the vegetable/fruit vendor, inside the cavity @ the back of the spkr with a small portion of the plastic bag jutting out of the mouth of the cavity.Pour the sand after cooling, in the cavity, as explained by trittya and close the lid with the plastic cover.
@trittya will this process be ok ? will the results be the same ?
it will definately help to reduce the mess while removing the sand.
 

Bluu

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Once the plastic bag is full, how will you pull it out without spilling all the sand?
 

gobble

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rightly said.how about sand bags ? one can insert a plastic bag,the thin one given by the vegetable/fruit vendor, inside the cavity @ the back of the spkr with a small portion of the plastic bag jutting out of the mouth of the cavity.Pour the sand after cooling, in the cavity, as explained by trittya and close the lid with the plastic cover.
@trittya will this process be ok ? will the results be the same ?
it will definately help to reduce the mess while removing the sand.
vegetable vendor bag is biodegradable. After one year you find it in tatters.

But if you do use it remember to remove the Tomatoes, Brinjal and Garlic from it. :)

-G
 

Bluu

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Agreed, but it will still spill all over your floor when you try to remove it.
 

trittya

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Good explanation Trittya. BTW, would adding silica gel in addition to what you have suggested (to eliminate moisture builtup) makes sense?
Definitely makes sense, Sir.
Did not undertake it for the u/m reasons:-

* The dessicant pouches(silica gel/the like) would lose its moisture absorbing properties in a week in by becoming saturated. The puoring in and settling of sand and leadshot, I m sure you'll agree is, in itself quiite a job, so it doesnt make sense to go over it just to replace dessicant.

* Any audiophile worth the name MUST have about 6-8(or more) cloth bags (of size 3"x3" with a drawstring mouth) filled with silica gel crystals and suitably suspended/placed (do not tie it to the eqpt/speaker) out of sight, behind each component.

* Placing an additional bag of silica gel well behind the rear port may also work, but IMHO, considering the fact that the missions need at least a foot of breathing space from the wall, the efficacy of the dessicant for the sand may be mitigated.

* Do remember to replace the silica gel periodically, depending on the level of prevalent humidity. In less humid places, one can re-use it once, at most, by heating it on a low flame in a fry pan to evaporate the moisture.

Hope this helps.
Regards
 

trittya

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ROFL!

Trittya - What about removing the sand? I suppose it will be nightmare to pour the sand out. Imagine the mess!
Yeah, I dread the thought, too, but it can be easily done in the u/m steps:-
*Step 1
Prop the spkr face up on a pr of equally tall, padded benches/chairs in such a way that you have access to the compartment lid.
*Step 2
Gently peel off the caulk off the lid with a plastic spatula.
*Step 3
Pull the lid and let the sand flow.
*Step 4
Get a hollering from the wife, while trying to explain why it was absolutely necessary to use a freshly ironed & clean bedsheet to collect your precious sand& pellets.

Wish you the very best of luck for the last step. Do let us know what happened, LOL.

PS:- I'd rather not empty them at all, not in the near future, at least.
Regards
 
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