Fertin Full Range Speaker

[Cherel]

Hello, what about a new full range speaker ?

Anyone has heard about Fertin speakers ?
They are build by Atelier du Haut Parleur in southern France.

They have conventional magnet speakers and electrically excited speakers. I have tried their 21 cm with both engines and I am very fond of them.

This little wonder has a carbon spider and a resonance frequency of 27 Hz.
It produces a distinct 20 Hz at the same level than the mid frequencies, say 300 Hz where it exhibits a 96 db sensitivity.

For testing I had mounted the speaker in a B&W 802 at the place of the top woofer. The lower woofer was short circuited for the experience.
It was drived by an Audio Research D120 set in symetric, with a 47 ohm serir resistor an a correction network to flaten the response.

I have pictures and spl curves for the setup that I could send by mail if required.

[Cherel]

More info on Fertin 21S

I cannot find a way to set every thing under pdf format of appropriate size. Please find attached the SPL curves.

[Cherel]

Now, there is the correction network used.

[felixx]

Cherel
Could you please share the responce curve but with correction network?
Thx.
Also I saw there...... still need a supertweeter from 15khz up.
I know,it's hard work to achieve 27 hz on fs but still not good enough for upper area.

[Cherel]

Hi, felixx.

The response curve is already with correction network. It is difficult to listen to a magnitude rise of 15 db from lower mid to trebble without an efficient correction network.

For the bass, you are rigth, I have spoken of 20 Hz while it was 27 Hz, thanks for this remark.

Speaking of trebble, I have notice for a bit of time that there is above 7Khz less musique informations than rise time or small pulses or peaks. These pulses and peaks bring presence and life to the musik provided they are in phase with the musik.
The property of full range speakers is that they warrant the phase issue and in turn the phase issue warrants the life of the musik.

To crossover them with super tweeters is a mixed experience of good and bad and to my knowledge more bad than good. But it is worth trying for the sake of the experience.

For the listening I have a much better trebble perception with the Fertin 21S which cut at 15 Khz than with the B&W802 that goes up to 25Khz. Is'nt that strange ?

The real difference is in the trebble directivity of full range versus the directivity of small dome speaker.
But there is the trick. Very few instruments deliver omni directionnal trebble.

What should do the reproduction of recorded musik ?

[felixx]

Peter Daniel...on this forum has this carbon full range driver into "infinite" open baffle design.

For the listening I have a much better trebble perception with the Fertin 21S which cut at 15 Khz than with the B&W802 that goes up to 25Khz. Is'nt that strange ?

Maybe because of the high raising response into 9k area.
Anyway the magic of single driver remains.I have Supravox 215 bicone on OB but still need supertweeter on top-Fostex T925A.

[Cherel]

True the 9Khz peak plays a role in that perception.

I have considered to implement a rejection filter as I did for a 3Khz peak. But a filter is also a phase rotation.

I understand that the Fertin speakers have been often set in infinite baffle.

A box that handles properly the back emission may improve the basses without deteriorating the mid and trebble.
The Qt of the 21S (0.435) is almost ideal for a Voigt Pipe.

[hum4god]

i will order the Fertin 20ex soon and plan on installing it into small open baffles so achieve a natural rolloff around 150 or 200 hz and complement witha boxed bass system activly crossed over and amplified .

i am very interested in the topic of correction network for Fullrangers .

i am also still looking for a good bass crossover with phase alignment and also something to measure in room frequency response to determine how my driver rolls off and where to xover the bass .

another intersting topic would be impedance matching between amp and FR or what damping factor is best ?

what i read so far is that Set amps with lower damping factors ae better suited for FR .

malcolm

[planet10]

Originally posted by hum4god

what i read so far is that Set amps with lower damping factors ae better suited for FR .

For many FR but not necessarily all....

dave

[Cherel]

Hello Malcom.

From what I could read the Set Amp is a One watt amp with a 6.6 Ohm internal resistance.

1 - One Watt might be enough if no correction network were applied on the speaker. But the 20 EX Fertin needs correction. So one watt is too short.

2 - I understand from those who use the 20 EX that the internal amp resistance should preferably be higher, 15 or more ohms.

3 - Simple amps well adapted will probably be the F1 (80 ohms) or F2 (15 ohms) of Nelson Pass. Their power range (5 to 10 watts is more adapted than the Set Amp).

4 - A single End class A with 300B or 845, might be very good as well.

4 - An other choice might be the Amperotron of Jean Marc Plantefeve, see the net.

5 - You might as well try to use your F3 and play with the NFB of it in order to increase its internal resistance.
May be you should ask Nelson how far you may decrease the NFB of F3 without encountering problems.