Hi Ronnie, I'm glad you solved your trouble and it was just a matter of balance in the frequency response range.

The singer's formant is an ability that opera singers learn, in order to stand louder than the orchestra and be heard at the rear rows of the theatre. The "trick" is thought to consist in the lowering of the larynx while singing, this changes the resonant properties of the vocal tract and enhances armonics that while speaking are usually way lower than the fundamental tone. The singer's formant is the result of fusing several armonics into a wide range of frequencies (this is a formant and these formants is what allow us to diferentiate one vowel -/a/ for instance- from another -/e/ or /i/-). Formants are what make your voice different from mine and what make each vocalic sound distinguishable from another. Singers learn to make their throats resonate into a frequency range at which the orchestra has lower energy (above 2 or 2.5 KHz) and place a great amount of acoustic energy into that range. This singer's formant can be above the 105 dB in a frequency area where the orchestra is no louder than 85 or 90 dB. The shape and width of that formant can make a singer's voice more palatable than another's, sound more powerful, warmer or more ear-drilling.

You'll find an explicative graph in here: http://hyperphysics.phy-astr.gsu.edu/hbase/music/singfor.html

Ronnie wrote:

The room modes I thought I had to battle suddenly disappeared the other day when I decided to try stuffing the boxes a bit. Suddenly everything fell into place :-) I guess I can do better than using little cushions though... Do you have a "chemical name" for that furniture stuffing you lined the walls with? Will I find it in IKEA or the wood/hardware store?

I relay do not know what it is. I bought in a regular local cloth shop. It is very light and has hair from one side. In fact it should not be anything special. The idea is to eliminate the parallel surfaces and to inject a very slight diffusion/adsorption into the tope reflections at HF.

Ronnie wrote:

I have tried a pair of Alted 902 in 400Hz tractrix instead of the Fostex, but haven't been able to make them sing at all. So far they look like little trumpets and sound like little trumpets.

The Altec 902 never was a good driver. No mater what you do by a ferrite magnet can’t serve HF.  However you did used then in their atrocious original Altec “caned” horns… it must be horrible….

Ronnie wrote:

Two more LF boxes are under construction.

You do need to work with LF. Never run then empty-boxed but glue the box with 3-5cm of high-density foam. It will extend the virtual volume of the boxes. Also do consider adding other LF section(s) atop. The driver you used for LF are very soft clipping driver but still do not stress them – you will not damage then but the stressing them will affect sound: a driver per channel is too little for your room.

Ronnie wrote:

The system sounds absolutely lovely to me.

Those type configurations are always winning. Do not forget unload the LF form the upperbass horn and be carefully with Fane’s HF. It might run quite high in this horn but the HF extension (over 700Hz -800Hz) will not be as good as the lower knee of you MF driver. In fact it is not exactly knows which of your driver will handle 700Hz-800Hz better: Upper bass of MF. You have to decide to yourself. At some frequencies the MF will begin to suffocate and at some frequencies the upper-bass driver will have too heavy cone and will sound too dirty.  Still if you have  400Hz tractrix then you must not dive lower then 750-800Hz with this chanal…

Rgs,
Romy the caT

PS: BTW, do not forget drive the horns with a SET....

BOX STUFFING
"It is very light and has hair from one side." and "glue the box with 3-5cm of high-density foam".
- Do you use both a high-density foam and the light and hairy material on top of that, or are they the same?
- Do you mean to glue on 3-5cm thick chunks of dampening material, or to spray on something like polyurethane foam spray (the hard stuff that I believe John used to fill your back chambers with in order to DECREASE internal volume)?
Apparently there are flexible types of foam too.. www.pfa.org

1" HORNS
Are your referring to these as original Altec horns: http://www.webbtjanst.se/lenco/images/loudspeakers/pict4256.jpg ?
I don't know if Altec made similar horns, but these are from a shop called Stereo Lab, or something similar.. Quite a hard resin material, but not metal-like.

CROSSOVER
I changed the crossover point between Fane and Fostex from 1850Hz to 925Hz. I did it mainly to see if it would cure the shouting Altecs. The new XO point stayed when the Fostex were put back in.
I believe it works much better, but there were many adjustments around the same time.
Thanks for reminding me to unload the mid bass horn from LF! I had completely forgotten.


"PS: BTW, do not forget drive the horns with a SET...."
-Oh rub it in why dont ya! ;-)
This may become 6 channels of SET: http://www.webbtjanst.se/lenco/images/loudspeakers/pict4255.jpg

Thanks for your help!!

Ronnie,

The stuffing the back chamber in upper bass horn and stuffing a sealed enclosure have totally different purposes. In the firs case we need to decrease volume of the chamber in the second to increase it. The polyurethane foam spray is not foam acoustically speaking but juts a filler of the back chamber space with wish the resonant frequency of the horn might be tuned. The foam that used in the sealed boxes is actual furniture foam, the swift airy material. They are available in different density. When I mentioned the “very light and has hair from one side” I revered to the cloth that I hanged atop on the sealant. When I referred to the Altec horns it was the multi-sell Altec horn that I have seen at your picture.

Rgs,
Romy the Cas