General question out of curiosity - Who discovered that SK12FRX can be used for Hifi ?

[Naveenbnc]

I am trying to find out if there would be any improvement in low end response with a sealed box Vs current OB

the below is the freq-response provided by Ahuja
If my understanding is correct, the graph starts to roll off at around 190hz @ around 98dB (F0)
F3 would be around 170hZ @ 95dB
(I am assuming my current OB is giving similar F3)

If I make a shallow sealed box of size 20"x20"x8"
I am getting an F3 @ 78hZ and an F10 of 51hZ (please see the below green graphs from simulation)

With this basic data, can I assume that we can get better low end response by making a sealed box ??

(errors possible in my assumptions or approach....I'm just trying though...)

 

[Sumanta]

A sealed box (any cabinet as such) will generally add colour to the sound if it is made by common (general) marketplace method. That in general (I know I am repeating this word) is called as boomy sound which is generally conceived as better bass sound.

If you can increase SPL of lower frequencies in OB, it will generally be better than general sealed box performance.

Read Linkwitz many a times, that will make up your mind before you try too many options.

 

[Sumanta]

Riley's SW - Thor, have a read.

 

[Naveenbnc]

A sealed box (any cabinet as such) will generally add colour to the sound if it is made by common (general) marketplace method. That in general (I know I am repeating this word) is called as boomy sound which is generally conceived as better bass sound.

If you can increase SPL of lower frequencies in OB, it will generally be better than general sealed box performance.

Read Linkwitz many a times, that will make up your mind before you try too many options.

thank you so much Sumanta for the inputs.

The current requirement is for 5.1 HT setup.
My center channel is Ahuja FR mounted on a simple baffle.
I placed it very close to the rear wall (not a good placement) so that it hides behind the screen.
As of now, vocals, highs etc are simply super. !!!
Sometimes I feel the sound signature is a bit dry, and little more low end from center channel may sound richer.

That is where I thought a sealed shallow box may improve low end compared to current OB style.
Simulation shows that I can get an F3 of 78hZ and an F10 of 51hZ with a sealed Box ....
I suspect my current OB style is not going that low. So I am giving a try ....

This is a new hobbie for me ... so I am being aggressive and taking many decisions in a hurry.
As the time passes by, I may show some maturity and learn to read and think more before I act
But right now I already made a box

Secondly, I am driving my center channel directly by an AVR. I am not sure how I can improve the SPL of low end in this scenario...
I will see if there are any EQ settings for individual channels in AVR.

 

[Naveenbnc]

Riley's SW - Thor, have a read.

I will read and learn .... thanks a lot for sharing ...

 

[Sumanta]

Have a towel wrapped at the back of your center speaker cabinet. Towel should seal the back completely. You may need two towels to cover back only and then the other for lower and upper opening. You can try it by asking someone to hold those towels.
I think with this you will get better bass but will not lose transparency of OB.

This is just a guess of mine....I have never tried it personally but by reading some design, I think this will work to increase SPL of lower frequencies.
Changing thickness of the back cover and its sealing will impact the SPL value.
Since your cabinet is having a tapering depth towards lower side, you can keep the lower part open as well but still that should give better lower end SPL.

Please do let me know your observations for my learning.

 

[MaheshGB]

You can use led swivel mount for center channel, be away from wall

 

[MaheshGB]

UNIVERSAL FLEXIBLE WALL MOUNT , VESA 200*200.MOVABLE WALL MOUNT SUPPORT UPTO 32" TV https://www.amazon.in/dp/B00NBT9RUG/ref=cm_sw_r_cp_apa_i_uuqhCb6A7Y56N

 

[Naveenbnc]

Have a towel wrapped at the back of your center speaker cabinet. Towel should seal the back completely. You may need two towels to cover back only and then the other for lower and upper opening. You can try it by asking someone to hold those towels.
I think with this you will get better bass but will not lose transparency of OB.

This is just a guess of mine....I have never tried it personally but by reading some design, I think this will work to increase SPL of lower frequencies.
Changing thickness of the back cover and its sealing will impact the SPL value.
Since your cabinet is having a tapering depth towards lower side, you can keep the lower part open as well but still that should give better lower end SPL.

Please do let me know your observations for my learning.

Hello Sumantha....

Very interesting suggestion.
Since i mounted the OB center channel very close to the wall.... I searched a lot to find out the ways to completely/partially absorb the sound waves behind the baffle. (To avoid reflections from wall)

I thought of covering the rear side of the baffle completely with some absorption material.

In that search... i found this link

https://www.hifivision.com/threads/...ap-diy-acoustic-panels-check-it-people.72609/

Later i realized it's not possible to absorb with towels So i left that idea.

But as you said, if the towel idea can give a little bass or increase little spl without coleration, it will be an interesting experiment !!!!

And now.... Here is the set back....I can't do this experiment unless I make a new baffle..... As I said earlier i do some attempts in a hurry !!! I already made a box with my existing baffle...

 

[Naveenbnc]

 

[Naveenbnc]

Next time when I cut material, I will cut an extra baffle and try your idea with towels

 

[arunkvivek]

Naveen, Do you have a carpenter in your pocket? All your work seems to be CNC cut - smooth edges.

 

[flute]

Naveenbc you seemm to be curious but I wanted to discuss and clarify a few things but you seemed to be busy and dont want to talk when I tried.

 

[Naveenbnc]

Naveenbc you seemm to be curious but I wanted to discuss and clarify a few things but you seemed to be busy and dont want to talk when I tried.

Sir, I apologize for not calling back to you... Last two weeks have been too hectic due to some reasons....
Will call you without fail ....

 

[Naveenbnc]

Naveen, Do you have a carpenter in your pocket? All your work seems to be CNC cut - smooth edges.

I had some frustrating and disappointing experiences with local carpenters ....They never understand the perfection we look for.... so cnc is a huge relief ....

 

[flute]

Ok I will be waiting for your call and I wanted to discuss as I am a serious diyer and wasted a lot of money so I thought of helping fms.

 

[Naveenbnc]

just an update on the performance guys ...
As you can see from post #57, I converted my OB center channel to a sealed box.

After making the box, I found one advantage and one disadvantage.
DISADVANTAGE:
In OB, vocals are a bit raw and punchy.... while the sealed box made the vocals soft.
For my taste, OB vocals are better than Box !!

ADVANTAGE:
When it comes to action movies with explosions and gunshots, OB was a bit shouty and fatiguing.
Sealed Box made such sounds soft and less fatiguing.

However, this driver needs a huge box for getting little bit of low end extension.
My center channel looks ridiculously huge and funny.
But if it goes behind the PJ screen, we can't see it any way .....

 

[Naveenbnc]

I am giving one last try. Please help me if you can......

In the beginning i just bought drivers like crazy. (U can understand over excitement i guess...)

Is there any FULL RANGE driver that can perform better than Sk12Frx without being too expensive ??? I want to buy 5 drivers to make my 5.1 HT

The only drawback with Sk12Frx is that it needs huge boxes to perform. Center and surrounds look awkward. And in case of OB it rolls off around 160-170hz

Apart from my practical requirement, I really wonder, nothing can beat Sk12frx in that price range ???

 

[Naveenbnc]

I am ok with any size of driver from 4" to 12" as long as it can perform in a compact box.

May be i repeated this in other threads...
Advantages with Sk12Frx:
1. High sensitivity - my AVR can drive all 5 channels easily.
2. Can go pretty loud (feels shouty sometimes, but manageable)
3. Gives great vocals as a center channel
4. Don't need a tweeter.

Disadvantages:
1. Needs a large box
2. Won't give low end below 170hz in OB.
3. Will give low end in a box, but it should be large.

So my current requirement, any driver that can perform as good as sk12frx, but in a compact box. Or, any driver that can give low end down to 80hz in OB.

Nothing can beat sk12frx in that price ????

 

[Sumanta]

Has anybody tried 200 W version of SK-12 FRX, that is the DX12-F200 or DZ12-F200?