Pass SLOB Build Discussion

[Gyuri]

Nice looking OB!

Just a thought on your woofer selection.
In this case, I'm not sure, bigger is better.
As I can see, this woofer has 258g Mms.
Eminence Beta 15A has only 60g Mms.
My 18" Eminence 18415 has 123g Mms.
I don't have corresponding Mmd datas.

Are there anyone who has experience and knowledge on this matter?

Regards,

Gyuri

 

[gadut]

Gyuri,
I have read several post for woofer OB selection and I'm not sure whether I understand it or not. Looking at ae dipole 18 which is regarded as high quality woofer for OB but still has a weak motor like eminence alpha. while my 21" subwoofer has twice mms but thrice BL. What i believe is that the bigger is always better for OB to produce low bass. since i will use active xo and bass boost anyway for the subwoofer, i dont worry too much now.

some progress, 2 baffles already cut and cleaned, 2 x 3/4" meranti plywood with 20kg each baffle. centre area is covered with Batik textile and oak veneer on both side. however plain oak + teak oil looks pale, i want contrast colour. I got inspiration from ak47 wood stain using Iodine, then i apply it on those oak veneer. 2 layers already give vibrant colour, i'll try until 5 layers.

 

[gadut]

finally front baffle completed, but i forgot to consider subwoofer depth for slot loaded baffle, the magnet block each other. it seems i have to add another 6" to the back panel in order to separate them.

in 3x5m living room, i put audio video chain on 5m side, not ideal at all but that what i have.

 

[Soundhappy]

What you think about mechanical vibration isolation from the floor contact ?

https://www.parts-express.com/penn-...source=google&utm_medium=cpc&utm_campaign=pla

Have a nice day

 

[Gyuri]

Very nice work, Gadut.
Never mind, everybody makes mistakes.

I just asked above because my experience shows although 18" Eminence 18415 has a bigger and deeper bass, I feel it has some lack of stiffness compared to 15" Eminence Beta 15A.
Compared in the exactly same setup and settings.
So my goal will be using Beta 15A in front baffle, and 18415 in a bottom firing slot loaded mode.
Sometime in the future.

 

[Gyuri]

D. Buxtehude - Prelude in D minor, BuxWV 140 - M. Chapuis:
https://www.youtube.com/watch?v=hWMTdFTDgPg
I'm not sure Buxtehude did play this work in this manner.
(Who can be?)
Perhaps Chapuis plays it too bombastic, but I like it very much.
Great test song for bass.
It has a sibling I like it as well.
D. Buxtehude - Prelude in A minor, BuxWV 153 - M. Chapuis:
https://www.youtube.com/watch?v=Swrp34fwIvc

 

[perceval]

in 3x5m living room, i put audio video chain on 5m side, not ideal at all but that what i have.

Many of us also have constraints. We do our best with what we got.

But I think you will need a bigger TV ! It looks so small between to the open baffles!

 

[gadut]

What you think about mechanical vibration isolation from the floor contact ?

Have a nice day

this kind of rubber feet already in my choice list, beside using thick carpet. but i'll have to hunt heavy duty rubber feet, with dual 21", in total each side will be more than 80kg

Very nice work, Gadut.
Never mind, everybody makes mistakes.

I just asked above because my experience shows although 18" Eminence 18415 has a bigger and deeper bass, I feel it has some lack of stiffness compared to 15" Eminence Beta 15A.
Compared in the exactly same setup and settings.
So my goal will be using Beta 15A in front baffle, and 18415 in a bottom firing slot loaded mode.
Sometime in the future.

When I visited Sinar Baja show room and i mention to the sales staff that I want to test 21" subwoofer for my home speaker (showroom has a mixer and 1kW PA amplifier for testing) , he asked me several time "really???" luckily the sales guy has technical background, then we discussed on what type of music that I prefer.

Usually PA guy will use 15" for modern instrument like guitar/kick drum and will add 18" subwoofer which has character as fast response. While my preference is for the bass that is produced by giant drum with more than 1m diameter, or dinosaurus foot step. sales guy finally understand why I choose 21", because the character of 15" or 18" can be said as Fast bass, while 21" as Fat bass.

He also mention that PA guy usually buy 15" or 18" subwoofer, rarely buy 21". While for theater or church, usually the order is for 21" sub.

hopefully my message is understandable

Many of us also have constraints. We do our best with what we got.

But I think you will need a bigger TV ! It looks so small between to the open baffles!

yeaa that 32" tv looks tiny now, 55" curve tv is already on my waiting list but this will be after i get another pair of 21" for slot loaded.

 

[Gyuri]

Yes, of course, we can exactly understand each other!
I can remember, when my first try OB dancing around the room when I listened some odaiko drum music.

 

[gadut]

When i was a child, i liked to play with the big drum which is always available on every mosque. The bigger will give me more fun to play with the sound can be heard in the range of 500m - 1km.

somehow i never like the sound of kick drum, i mean from the kick drum it self not from amplified one, the bass sound is sissy to me

 

[Kjeldsen]

big kick drum

 

[naca5]

waow already 19 pages
I'm wondering if a tweeter will help
The curve drops after 8-9kHz

 

[Gyuri]

I'm more worried about sharp roll-off below 45Hz.

 

[korpberget]

this kind of rubber feet already in my choice list, beside using thick carpet. but i'll have to hunt heavy duty rubber feet, with dual 21", in total each side will be more than 80kg

.

How about some Volvo 240 engine mounts? Used to be cheap and should be easy to apply as feet.

 

[korpberget]

An externally hosted image should be here but it was not working when we last tested it.

 

[gadut]

waow already 19 pages
I'm wondering if a tweeter will help
The curve drops after 8-9kHz

so for all this time you listen to this 'dullness'?

How about some Volvo 240 engine mounts? Used to be cheap and should be easy to apply as feet.

i'll have to find the right one someday

completed active xo opamp+bass boost for sub low, both of them have potentiometer to adjust cutoff freq (set to lowest around 60Hz) and 20Hz gain is set to maximum. the output is sent to aragon2004 to drive 21".

for 12" mid and horn, I'm using 12dB passive xo LPF 1.1kHz and HPF 2.2kHz.

Already listen for 2 days on good audiophile recording and I'm blown away when they are pushed to play very loud but no sign of stressed sound. and yes with thick carpet on bottom OB, I can feel that the floor is shaking on deep bass.

But when I listen to standard pop album (Celine Dion -
Let's Talk About Love) is a sample of good singer but recorded badly. the biggest issue is the dullness, where previously i always use EQ on foobar for last 4 octave.

Then I reminded on jbl gto 19T 3ohm car tweeter that i used previously to accompany alpair 10p, it has a crisp treble that i really like but lower sensitivity 93db compared to my 104db horn. I can't hear anything coming out from the jbl when connected in paralel to horn.

I can feel the benefit of having multiple amplifier now, with J2 clone 20dB gain that power mid+horn, i have mauro penasa gainclone 32dB gain that will match horn and jbl level with 3.3uf caps filter. Now i do not miss any high treble anymore

if my wallet permit, fostex t90a should be an ideal solution.

 

[naca5]

Hi
Does anyone ever tried a Supravox in OB's?
http://www.supravox.fr/anglais/haut_parleurs/400_2000_EXC.htm
Looks very interesting as you can set the QTS (depending PSU DC out)....

 

[gior]

It seems people will still have an opportunity to get a (sort of) B5
http://www.pureaudioproject.com/pap-c1-custom-active-analog-crossover-open-baffle/

 

[Nelson Pass]

It's similar to the B5, but is optimized around what PAP needs specifically
with regard to range of crossover frequencies and equalization.

Delivery should be later this month.

 

[Gyuri]

So this is why we can't get closer information about discontinued B5.