humour a n00b / 2 way stand mount / cabasse dom40

[js iyer]

i want to build a sealed two-way stand mount, with very comfortable and effortless response down to about 60 Hz, below which i would like the response to taper off, very smoothly... i will add subs at a later date.

* the tweeters will be Cabasse DOM40s... a member here has most kindly given me a pair... i can get almost no info on them, attached it the pdf that the donor could find...

* I will go biamp'd and active, with a digital speaker management processor, probably the behringer dcx2496. maybe one day i will be able to afford the deqx.

I am under the impression that when you go active like this, it becomes easier to match drivers (particularly when nothing much is known about the tweeters), notch out rogue frequencies, fine tune crossovers and filter slopes, optimize the response for the room etc. etc. Also i think i will die before i get around to really understanding enough to build and modify analog crossovers... as somebody here said, "its a bit of a black art"... which i neither have the time nor the means nor the aptitude to learn.

when i actually start building, i will have a great many more questions, but for now, here is where you can help me... please take a look at the stupid mock up image, which is just a vague representation of how it could be... the cabinet can be as big or small as is needed to get the required performance, this is just a random starting point:

Help me pick a mid-bass unit. will i get the LF extension i want i a sealed cabinet? I want to keep it @ <$100/driver, though i am reluctantly willing to go higher... the more expensive it is, the longer it will take me to get around to it. For starters, i found a few, which i mostly picked on the basis of their relatively low 'fs'. (once again, a random criterion since i don't really know how to read 'ts' parameters.)

* SEAS Prestige CA18RNX (H1215) 7" Coated Paper Cone

* Aurum Cantus AC-180F1 7" Woofer

* SEAS Prestige L18RNX/P (H1224) 7" Aluminum Cone

* Usher 8836A 7" Kevlar Woofer w/Truncated Frame

* ScanSpeak 18W/8545 7" Paper Cone Woofer

* PHL 1361

once we have frozen on the mid-bass unit, we will get into cabinet volume and such things.

How wrong have I got it? is the project doomed to fail because i do not know enough and am approaching this too randomly? (btw i have built a couple of pairs of full rangers to great satisfaction... i am involved with sound to make a living, i have a measurement mic, software and great ears, and i have tuned PA systems several times... so i'm not totally green!

I will be listening to every type of music on these, from Arvo Pärt to Pantera. My room will be 14' x 18'... if/when i want serious spl, i'll add subs. i am not looking to build the ultimate audiophile system... i guess i just want to nail it at the threshold of diminishing returns...

thanks for any inputs...

js iyer

[sdclc126]

If you can stretch your woofer budget up to $110 the Usher 8945P or 8945A (slightly better bass response) are what I'd recommend - extremely low distortion resulting in crystal clear, highly detailed reproduction - cleaner than the 8836A -

Zaph|Audio

They are frequently on sale at PE for under $100, if you want to try to wait. Otherwise do it now and enjoy.

[PeteMcK]

re:'once we have frozen on the mid-bass unit, we will get into cabinet volume and such things. How wrong have I got it?'
I'm sim all the above drivers in Winisd or Unibox first, and see which match your already decided criteria for a Stand mount - you must have some sort of target volume in mind?
There is usually a compromise between cabinet volume and low end extension...
bear in mind that paper cone drivers are usually easier to crossover..
the Cabasse tweeter seems to be crossed over fairly high in the PDF given, I'm not sure it will be suitable for a 2 way with a 7" driver ,you'd need freq response & impedance plots to decide

[PeteMcK]

found these spec here: Cabasse haut-parleur DOM40

Re 5.7ohm
Le .04mH
Fs 1150Hz
Sens 91dB
P 45W

with an Fs that low, should be good for a 2 way...

[js iyer]

Re 5.7ohm
Le .04mH
Fs 1150Hz
Sens 91dB
P 45W

with an Fs that low, should be good for a 2 way...

thanks very much for that. sorry i missed it.

you must have some sort of target volume in mind?

actually, no. no target volume, but i'd prefer not to exceed the 32 sq.ft. limitation of a standard MDF sheet. This is one of the reasons i want to custom design... i am not limited by cabinet volume or shape... i am in india, and i have very good carpenters who are more than happy to work for $10/day, so i don't have to settle for a simple rectangular box.

If you can stretch your woofer budget up to $110 the Usher 8945P or 8945A (slightly better bass response) are what I'd recommend - extremely low distortion resulting in crystal clear, highly detailed reproduction - cleaner than the 8836A -

thanks sdclc126. looked up zaph's comparison... so i'll put the 8945A on top of my list of possibilities, for now. until somebody is able to suggest a decidedly better alternative. I'm also wondering... if at a later date, i want to replace them with a more expensive alternative (such as the PHL), would it be a big PITA?

sim all the above drivers in Winisd or Unibox

i'm simply not able to wrap my head around this stuff. 'ts parameters' are not my cup of tea... Checked out both of them... neither of them has the data on any of the drivers we're interested in (at least as far as i can tell).

tried to create a new model for the usher 8945A in winisd, with the info available on the partsexpress page... no use... it says,

'consistency check on the following parameter groups failed'...'Qts, Qms, Qes' (i know the solution is probably simple, but i'm trying to stay out of that jungle. i'm not that kind of adventurer.)

anyway, i'm hoping that somebody here, who is used to doing this stuff on a regular basis, will be able to tell me what driver and cabinet volume will let me get to my desired ''60 Hz with a smooth roll off in a sealed cabinet' ideal."

thanks again and please keep them coming,

js iyer.

[56oval]

Hi js
Why not use the Cabasse 21M18 mid/bass driver ,Cabsse use this with the Dom40 in the Farrella 400 2way floor stand they also made a stand mount Goelette 500 using the same driver combo .

Cheers

[js iyer]

Originally Posted by 56oval

Hi js
Why not use the Cabasse 21M18 mid/bass driver ,Cabsse use this with the Dom40 in the Farrella 400 2way floor stand they also made a stand mount Goelette 500 using the same driver combo .

Cheers

this is from another forum.

I am Larry from KRK. I am the senior design engineer and have been with the company for the last 12 years. This is my first post to a site. Someone sent me this thread and I had to sign up to reply.

The 9000B woofer is the Cabasse 21M18. We have tried our damnedest to get more. We asked for a minimum buy qty & they said they will no longer manufacturer products for other manufacturers.

thanks for the suggestion,

[sdclc126]

Originally Posted by js iyer

thanks sdclc126. looked up zaph's comparison... so i'll put the 8945A on top of my list of possibilities, for now. until somebody is able to suggest a decidedly better alternative. I'm also wondering... if at a later date, i want to replace them with a more expensive alternative (such as the PHL), would it be a big PITA?js iyer.

Swapping out drivers always required crossover re-design - whether or not that's a PITA is up to you.

The more relevant question, I think, is why do you think you'd need to? A "decidedly better alternative" may not exist while a more expensive one may not be necessary. The Ushers are definitely not a temporary compromise until you can afford something "better" - they are among the best drivers available at any price and in light of the competition one of the best values too.

[js iyer]

thanks again sdclc126 points duly noted, and i'm glad that more expensive drivers will not be required.

Swapping out drivers always required crossover re-design - whether or not that's a PITA is up to you.

since i'm going active with external digital loudspeaker management, a 'crossover re-design' does not involve physically sourcing and putting together analog components. regardless, this is probably moot, since i may never need to change the drivers.

so now, can somebody help me specifically with this please...? what volume of box will get me a comfortable 60 Hz in a sealed box, with the Usher 8945A...

thanks,

[js iyer]

ok, i'm stepping into the very jungle i wanted to avoid. got winisd to work with minimum 'ts' parameters fed in (usher 8945A)... and i'm getting thoroughly confused.

in a sealed 20L cabinet, -3 dB is @ 90 Hz, -10 dB is @ 40 Hz
in a sealed 50L cabinet, -3 dB is @ 100 Hz, - 10 dB is @ 37 Hz

It seems that a 20L cabinet measures up almost as well as the 50L cabinet! WTF?! what am i missing?