Fertin Field Coils in an Open Baffle?

[dwhistance]

Hello

I'm very new to this so please pardon any silly ideas I have. I have long wanted to try a single driver open-baffle loudspeaker to be driven by my Supratek Merlot SET's. After doing lots of reading I have decided to try some of the field coil drivers given their higher efficiency (and the hyperbolic statements about their sound quality). This of course narrowed the choices considerably to either the collectable, and very expensive, vintage drivers or the modern ones from Supravox and Fertin. Given a preference for new drivers and an incredibly prompt and very enthusiastic response from M. Salabert at Fertin I am inclined towards the Fertins, specifically the 20EX Carbone.

Now to the question. I have seen designs for several open baffles on the internet that are supposed to suit this driver, particularly the "JE Labs" one which will probably be my starting point. Fertin themselves also have an interesting sand filled open baffle design that they suggest for this driver which can also be used with a woofer to fill out the bass if required, however both of these designs are fairly wide and therefore not "living room friendly". I have seen the pictures of James D's Quasar design(s) on this site which are much more domestically acceptable. Would this design, or a variation of it suit the Fertin Field Coils? Would it need the extra woofer?

Regards

David Whistance

[IslandPink]

Ah, interesting to find another OB fan drifting into the WD forum .
I tried to raise interest in Supravox drivers a while back , but the thread was (very) slow-moving !
I'd like to offer lots of advice, but really , I'm waiting for JamesD to resurface on the forum and help me ( and lots of others ) out again with his superb speaker/OB knowledge .

I'm inclining towards Supravox 165 or 215 alnico units, with some sort of 12 to 15" bass helper, but I haven't got the skill to sort the job out yet .

Have you considered PHY too ?
I must admit I need to research the Fertin drivers .
ChrisV may offer opinions eventually .

More soon,
Mark

[IslandPink]

This was the thread about Supravox , mostly my stream of consciousness :

http://www.world-designs.co.uk/forum...ead.php?t=2102

MJ

[dwhistance]

Mark

Many thanks for your replies. I had read the earlier threads with interest but they seemed to peter out a bit. I'm fairly sure I'll order the drivers later this week and put them in the JE Labs baffle, without a woofer, to start. I can then progress things from there as knowledge and time permits.

Have you considered building the Supravox "Panneau Plan" open baffle as shown on their website for starters? It looks relatively straightforward to build, has a very simple "crossover" (if it can really be called that), and uses two well respected drivers that could be used in one of James' baffles later on ?

David Whistance

[petercom]

If I were you I would stick with the recommended baffles. They may be wide, but that's to make sure that the bandwidth is right for the drivers.

Yes, the Quasars are narrower, and you can experiment with various degrees of folding the baffle back (too deep and it creates a resonant cavity) if you like. But it is a matter of experiment based on the driver(s) you are using.

So if you want to play safe and get the manufacturer's recommended performance, stick with their measurements.

[IslandPink]

David ,

I'm familiar with some sort of baffle plan for the PHY drivers ( sand-filled central sections, piano hinges etc , quite ingenious ) but I'm struggling to find the spec for an open-baffle design on the Supravox site . They have a picture of one , using the signature 215 bicone and the 285 GMF , but no links to construction details .

One big plus in favour of the Quasars is the transparency ( I mean the acrylic/perspex ) , which will be essentially in the long term if I'm to use an OB in my room . Maybe I will compromise on leaving the 'wings' opaque though .

I will try to look up the Fertin info .

Mark

[dwhistance]

Peter, many thanks for your advice. I'm sure that you are right and I should stick to the manufacturers recommendations. However as these things are fairly easy to put together I will probably put together a few with different dimensions and shapes to see which one is best to my liking. I will probably try to get my head around modelling them in Martin King's MathCad sheets over the next few weeks before to see if those offer any enlightenment.

Mark, the Supravox details are on their website under DIY and Open Baffle. If you press the Download button you will get the plans together with crossover information. The link is here: http://www.supravox.fr/kits/panneauplan.pdf

David Whistance