Little Boy: Yet Another TQWT 

   

"TQWT or not TQWT???"... That's the problem! ...
Is it preferreable to spend a lot money  and  have a lot of punch  with a horn ?... Or spend less  having  a little less impact  but still a great sound with a TQWT?
The only way is to experiment,  and after all I can say that TQWT is a *VERY* appealling solution.

Of course the results  depend a lot  on the type of driver you're using. And this colud be a very difficult choice: today there are several  suppliers of wideband medium efficiency spekers.

I've resolved the problem quickly,  reminding myself that  after all this'  "best buy" solution.
So I've left expensive speakers behind and I've decided to use high performance/price Fostex.
My TQWT use the old good FE164. Best results are obtainable with FE168sigma, but here money start to be a matter: actually one FE168S costs as much as TWO FE164....  ;)

Another interesting Choiche could be FE167 if you're looking for higher efficiency.
 

FE164 main Data:
 

FE 164 belongs to a old & famous family of speakers together with the "brothers" 103, 83,  204:
 

 

 

This  family  was originally intended for bass reflex enclosoures. Here are the suggested dimensions:

The FE164 is a 13cm fullrange driver with dual cone to extend the response. Here are the main specifications:

                     impedance                                 8 ohm
                        fo                                           50Hz
                  frequency response                       fo - 20khz
                     powerlevel                                 92dB/w(1m)
                     input power                               60w(Mus.)
                        Mo                                         6.9g
                        Qo                                         0.34
                    effective radius                           6.5cm
                    magnet weight                            330g
                     gross weight                              1.1kg
 

Frequency response is nice, expecially in the mid-high part of the spectrum. There are some problem with lateral response: on-axis the behavior is comparatively better.

Here are the dimension of another nice  fullrange minimonitor sound in the web for FE 164

FE 164 and 204 can be associated with a tweeter to refine the high part of the spectrum. In my opinon with FE 164 this is not necessary. anyway here are the suggested filters, unfotunately most data are in japanese...

My TQWT :
 

The cabinet I've choosen is pretty old: it dates back to the eighties and was made by G. Cretienne.
Originally the cabinet was intended for Triangle's spekers  but with some minor modifications (mainly the hole size and the internal damping) can be used for Fostex FE164/168.
Here are the main dimesions: 

 
 

Photo Gallery & Tips of Costruction :
 

Costruction is very easy, after all it's a common rectangular enclosoure with and internal wall.
I've used 18mm plywood, but  less expensive MDF can be used too. If you decide for this wood, is better to use 30mm thickness.

Great care must be taken with :

Internal damping is intendend to reduce the emission of higher frequencies from the frontal port, ad smoothen the "saw" response at lower frequencies. At the moment according to my room & listening position  common "moquette" on the bended wall and common adsorber on rear wall is enough.
I'm planning to reduce vibration from the fron panel (expecially at higher volumes), by covering externally and internally the walls with cork.

Here is a photo of the internal damping...

 

Note that to strenghten the joint with the openable wall of the cabinet a special slot with eliptichal wood joints  is used. This slot permits correct positioning of the removable wall.

To avoid air loss, the removable wall is sealed using silicon rubber for motor gasket. the silicon rubber is the thin black line.

 
 
 
 
Near the end: a number of screws are used to fix the removable wall. 
 
 
 

A lot of care must be taken during running in period. This period is very important because during it there's a progressive  smoothening of  the rigidity of spiders and suspensions.
I'ts advisable during the first listening sessions (about the first 30 working hour) to keep volume low.

My dealer said that for FE164 this period must last at minimum 100 hours.
 

Listening Impressions 
 

When I started the first listening session I was struck by contrasting feelings.
Sound was confused and the highs were missing, but the basses  were very deep, imaging and corence was very nice. Impact and dinamics was superior to my previous speakers.
 
To reach a compromise I  had to point the speakers directly to my listening position.
After about ten hours, my ears get acquainted with the new timbre and besides, I started to catch the improvement to the speakers.
Afterer 5 or 6 listening session improvements were clear, expecially my friends, who listened to them discontinuosly reported them: highs became progressively clear and nice, without the sparking attitude of other wideband speaker I've listened to.

'till now I've reached about 30-40 hours of life, the overall sound is very listenable. I've decided I don't need  any x-over or refining tweeter.
Now the speakers are almost paralleled, aiming to the rear wall of my listening room.

Trying to compare them to Lowther ....  I know that's not fair ;) ...... They definitely lack in the medium clarity and and overall "presence"/dinamics , but they don't have the "forwardness" that sometimes the o' englis exibit and  cost a tenth....

That's all folks, Listen and ENJOY!
 

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