Back Loaded Horn with FOSTEX, some questions...

[planet10]

Planet 10, any suggestions?

There are lots of choices depending on how low you want to go (keep room gain in mind, so a slow roll-off where you pay attention to F10 more than f3 is best). Paper cone probably better than plastic. Active of course.

I've been using some vintage foster 12", but have any number of 7s, & 8s that would do the job & there are even more in the catalogs. Each of these is capable of resonable performance to beyound 1k (the 12s were XOed at 2.5k for instance).

For new drivers the extremis 6.8 comes to mind. Bass like a 10", extension like a 6".

dave

 

[Guijs]

Well, i'm going to use it for music, so down to 30hz is more that i need. The JL 12W0 have an F3 in 37hz and F10 20hz in a 100L sealed box.

 

[planet10]

The JL 12W0 have an F3 in 37hz and F10 20hz in a 100L sealed box.

In a real room, you may still find you need to EQ them down a bit.... how extended are they at the top?

dave

 

[Guijs]

You mean that I could use a smaller box to down the F3? My room is small, 14m^2, 37,8m^3.

I don't know how they are in the top because I don't have al the parameters to simulate....

 

[planet10]

You mean that I could use a smaller box to down the F3?

No. That would push the F3 & F10 closer. A larger box so that the Q goes down, F3 climbs, F10 decreases. Q=0.5 is as low as you want to go thou.

dave

 

[Guijs]

Q=5 will result in a 577L sealed box, or I did some mistake here?

 

[planet10]

Q=5 will result in a 577L sealed box, or I did some mistake here?

Probably not... so somewhere between 100-500l. Try Q = 0.58? You can also go aperiodic to get the Q down a bit.

dave

 

[Guijs]

Q 0,58 is 217L. How about a nice T-L, tunned in 30hz? Wich first cross section size to use, 2*Sd?

 

[planet10]

Q 0,58 is 217L. How about a nice T-L, tunned in 30hz? Wich first cross section size to use, 2*Sd?

TL will probably need to be bigger. Those woofers either have a highish Q or a monster Vas. 100 litre aperiodic might be best.

dave

 

[Guijs]

Dave,


Not considering cabinet size, do you think that I can get better results with a T-L? If so, i'ts possible to build one, no problem.

 

[Guijs]

I can use the NHT10 too: http://www.madisound.com/nht10subkit.html


I have a pair here. It have better parameters than the JL for T-L.

 

[planet10]

Not considering cabinet size, do you think that I can get better results with a T-L? If so, i'ts possible to build one, no problem.

Depends on the driver, but it is always the 1st option i look at when doing a desgn.

dave

 

[Guijs]

What do you think about using the JL 12W0 or the NHT10? Wich parameters I have to worry?

 

[planet10]

NHT10 ... It have better parameters than the JL for T-L.

That should work... time to download Martin's tables & software....

dave

 

[Guijs]

Ok, thanks for the help!

 

[Guijs]

I'm plottting the NHT 10'' in the Martin table right now. Until now, the best results is with 1,8Sd, tuned in 30hz. F3 in 30hz and F10 in 20hz. Goes up to 100hz nicely.

 

[usa_satriani]

Hello,

have you ever heard of Davis ? They make great woofers that I am sure would fit a FE108EZ.

http://www.davis-acoustics.com/gb/31tca12w.htm

Atohm D300P04 would also fit, I use it with FE168EZ and FE208EZ :

http://www.atohm.com/hp.php?hp_ref=9

Maybe you could simply try a Fostex woofer, must be cool.

You are going to use bi amping and active filtering right ?

Greg.

 

[apassgear]

Guijs,

Been reading this interesting thread and wondered how are those FE108 doing. By now I'm sure they are broken-in, do you still feel the need to add a woofer?

 

[Guijs]

Hello,


The speakers are in "stand by" ultil I finish the tube amplififers. But, I tryed it in 2 different systems and the midrange is very, very good. Highs are good but needs extention, but I did not mess up with this a lot so maby it could be solved. Bass is good down to around 60-80hz, so in music that you need bass below it, you will need a subwoofer.

 

[s_zimble]

Hi all,
I have been away for a couple of weeks and just read the last conversation. Interesting indeed.
I have a question for those reading: I might have mentioned before that I will be building a pair of BLH using the FE87E's and basing the design on the recommended Fostex design, but would like to perhaps change a couple of things. Martain has wisely warned against changing the internal geometry and I uderstand the reasons better after reading his very complete horn theory papers (Cheers for that nice work, Martin!!). BUT I am not an engineer and want to know if keeping the same number of "bends" in the design is crutial or not? In other words, if the length and expantion of the horn remains constant, can I change the number of bends in the horn without changing the response? And, can I make the mouth rear firing (as opposed to front firing) and what could I loose by doing this?

Thanks for your help.
Stuart