SpeakerTalk

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

Hello everybody.
I'm french so you have to excuse my poor english.
I have a pair of SP1070 and i want to use them like Kef Celeste 3, in a 17 litres closed box.
Perhaps i dont search for correctly, but i dont find any parameter or specification like T/S or impede curve.
I need those informations for the crossover.

I try to associate the B200 with a Celestion tweeter : T3939.
Thanks for your answers.
David.

proffski · Posted: Thu Oct 24, 2013 11:55 am Post subject: Re: B200 SP1070 8 ohms

Welcome to the KEF forum!

The answer you seek for the KEF SP1075 parameters is not far from you!
Here: http://www.hifiloudspeakers.info/Anatomy/KEFDocuments/KEFDriveUnitsSpecSheets/KEFB200.G_SP1075SpecSheet.html

And here: http://www.hifiloudspeakers.info/Anatomy/KEFDocuments/KEFGermanGallery/pages/p37.htm
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

Hello. Thanks for your answer.
Is the SP1075 realy the same Embarassed

?
[img]http://forum.vintage-audio-laser.com/ressources/image/72868[/img]
[img]http://forum.vintage-audio-laser.com/ressources/image/72886[/img]

I have seen the data of the SP1075 and it's note 5 ohms and a bigger box.

If i can use those parameters, i can start to try to calculate a crossover.

Do you think i can find some curves ?

proffski · Posted: Thu Oct 24, 2013 4:58 pm Post subject:

No, it is mnot the same. I made a mistake, sorry! Smile

I would start by using a similar cabinet volume as the original loudspeaker.

If you can wait I shall see as to what I have in my library regarding the SP1070 this weekend.
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

Of course i can wait Very Happy

It's realy friendly.

proffski · Posted: Sun Oct 27, 2013 2:10 pm Post subject:

Sorry, I have looked everywhere but no luck.
As long as you stick to the correct cabinet volume and aim for Q of 0.7 then there should be no problems arising from your intended project.

At least my search found the 'missing' technical blurb I had mislaid for the KEF 104/2! Smile

I'll let you know if anything turns up regarding the SP1070...
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

Hello, my boxes are finish and i can try some crossover.
I ear them with 6db on the B200 : 1.2mh in serie and 12db on the tweeter : 4.3µf and 0.22mh.
The sound is ok but the level of the tweeter is higher than the B200. I have to put a resistance before it.
Bye.

speakerguru · Posted: Wed Nov 06, 2013 4:13 pm Post subject:

at mid to high frequencies, the woofer impedance is inductive, so a series inductor will just attenuate the woofer. It will not roll off at 6dB/Oct. You need a Zobel network across the woofer to make the load resistive then a series inductor will have the effect you describe.

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

Thanks for your answers Speakerguru.
But with my poor school english, it's difficult to understand all that you say Embarassed

And the internet translater is bullshit with technical words Shocked

Could you explain what is a Zobel network ?
For the difference of level between the speaker, i have read that the tweeter simply need a resistance in serie to be attenuate. Is it a mistake ?
If i am not enough accurate i put :
inductance in serie for the B200 1.2mh
capacitor in serie 4.3µf and inductance in parallel 0.22mh for the tweeter.
Cordially
David

speakerguru · Posted: Thu Nov 07, 2013 11:49 am Post subject:

Re: Zobel see http://www.trueaudio.com/st_zobel.htm
I'm sorry my technical French is not good.

you could select component values by trial and error if you can measure impedance.

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

Thanks a lot. Really interesting site.
I can't measure anything. I haven't got the equipment.
I hoped find the T/S and some curves in your excellent forum but visibly nobody have anything about this woofer.

DrBoar · Junior Contributor 20+ Joined: 22 Aug 2006 Posts: 21

with regard to zobel. Use the data from an other B200 unit and calculat the Zobel network and use those values. Even with values quie far of the correct ones the zobel will flatten the impedance rise a lot. This will be a large improvement over a not using a zobel even if it will not be perfect.

speakerguru · Posted: Sun Nov 24, 2013 11:04 am Post subject:

vans60 · Introductory Contributor Joined: 21 Oct 2013 Posts: 8

Hello.
After several tests, i can ear with pleasure my first DIY.
[img]http://forum.vintage-audio-laser.com/ressources/image/76075[/img]
I'm agree it's certainly not perfect without measure but they sound nice and the speakers are coherent.
I'll can measure them when a friend will instal his equipement and i can compare with the simulations.
Thanks a lot and mary christmas.