open baffle speakers or kits

[rivendell]

Hope someone can help

I had the pleasure a couple of years ago, to visit Ali Tait and he was kind enough to let me have a listen to the OB speakers he has, I had never heard this type of speakers before and was absolutely stunned at the sound they produced.

I spoke to a mate of mine at the time and waxed lyrical (if you pardon the pun) about these speakers, and the subject has recently reared its head again.

I have had a look on the net for kits as has he, but we are both more confused as a result.

So a few questions

Can someone recommend a starter kit, or point me in the direction of suitable suppliers, preferably UK.

FYI He is currently running a 20 wpc push pull valve amp which he wants to continue to use.

Are OB sensitive to room placement? He has about 2-3ft from the rear wall of his room but the can only come in say around a foot at the sides due to restrictions of silly this like furniture, sofa etc

What drivers would you recommend?, from memory Ali's speakers had 2 large bass drivers probably 15".

I have read conflicting information stating the the bass produced by OB
(oh and he likes his bass!)

Any help would be greatly appreciated

You know how it is you start a conversation get involved, then end up getting carried away and do all the spade work

Many thanks

[Black Stuart]

Hi Rivendell,
a subject I have nurtured for a few years now, never having had the space to work on the project.

Yes there is lots of confusing info available which is ever the way with hi-fi.

Size of baffle does matter and unfortunately most European homes have way too small rooms to enable a really large baffle or the WAF factor comes into play.

I bought from a WAD member a pair of AMT Grand Heils to use with a pair of (yet to be bought) 15" woofers. This makes for a simple two-way x/over, active of course. Why anyone perseveres with passive x/overs is beyond me - they have zero scientific credibility but some are tied to the past.

Bass - no box = no bass, coming at this obliquely - it is known that the AMTs' operate better in free air but there is a need to have some kind of material about 12" behind the unit, I suppose a way of putting it as something to brace the sound wave against.

So if a panel, preferably curved could be constructed to be used behind the woofer this should be even more effective than with the AMTs.

Again this needs to be moveable to find the most effective position.

The other negative with a lot of UK homes is the obsession with fitted carpets and underlay this really kills sound.

Think about using a large baffle but decorating it with artwork - instead of a negative you create a positive - if there is a woman involved let her choose the artwork, get her involved.

Those are my thoughts which I am sure most will not agree with but give you something to think about.

[rivendell]

Thanks for the response, assuming an active crossover is required, this will require some form controller?, will this also mean bi amping, which kinds kicks the 20wpc valve amp into touch or have i missed the point!

coming at this with no knowledge, what is the problem with a passive crossover?

[bob orbell]

Hi Rivendell and Stuart, take a look in the "gallery" at pre 65's home made open baffle speakers, they don't look much, but they sound very good. He may be on vacation at the moment, and may have some advice. BOB

[Shane]

He's always on vacation!


but right now he's at Owston, so won't be answering 'til Monday

[rivendell]

Thanks to everyone for the info, speakers look interesting!. The only comment i can make personally regarding OB speakers is based upon what I heard in Ali Taits home as I said.

Now i don't mind a bit of bass myself, and when Ali let me here them he played some tracks which i knew pretty well and i considered the bass to be more than adequate.

From memory if the track had a heavy bass line, Ali's speakers certainly delivered in spades. This is going to sound a very stupid comment, but i was stunned by the air and the huge sound stage and the sound just seemed to be "right" if that makes sense. They really stopped me in my tracks, ive heard a lot of speakers, and owned a few to boot, but i just havent heard anything like them, which is why the conversation keeps rearing head, when you sitting around with like minded souls gabbing about "what can we do next to extract everything we can from what we have or what can we drop into the mix!

However im a bit confused by the crossover situation. Im pretty sure Ali's speakers where driven by active cross and 2 amps.

So is it practical to use OB's with a passive cross over allowing my mate to use his valve amp, or does that kill his idea stone dead? I know that where he is thinking of placing the speakers, they would be set in around 10" from the side walls, sitting each side of a sofa, with the remaining space to actually sit the baffle maybe 15-20" wide tops and around 2 ft from the rear wall, which has light drapes covering half the rear wall, Does this kick OB's into touch?

Probably the sensible thing to do would be to have another chat with Ali Tait!

Thanks again for the information

[Greg.]

Rivendell, you have a private message

[pre65]

Originally Posted by Black Stuart

Bass - no box = no bass,

Those are my thoughts which I am sure most will not agree with but give you something to think about.

As someone who DOES use OB speakers I can categorically state that a bass speaker without box (ie on a baffle) certainly CAN do bass without the need for "reflectors".

And it is not mandatory to use active crossovers.

[Ali Tait]

Cheers for the nice comments!
The speakers are indeed actively driven, but don't have to be. The drivers are Visaton B200 8 inch full range driver, and the woofers are 15" Eminence Alpha, two per channel. I run them with a fourth order crossover at 200Hz.

You're welcome to come and take measurements if your friend wants to make a copy of them, they are easy to build.

[rivendell]

Ali

Thanks again for the invite, will get back to you on that shortly.

A few questions regarding the OB's

Given where the speakers will be located, the restrictions on cabinet sizes due to furniture etc, distance from side and rear wall, are they a practical proposition. My impression was the cabinets would have to be fairly big to work properly or have i got this all wrong?

What would you use from the framework of the speaker 18 or 26mm MDF or Ply?

Can you tell me where i would get a hold of passive crossovers

In fact, could you give me a rough idea of the sort of cost to build a set of OB's? Component suppliers, obvious we could deal direct with Visaton et all for the drivers

Would you recommend spiking the bases?

It would seem on the face of it that they shouldn't be a major problem to build or is that a statement i will regret making HA HA

Any suggestions, recommendation etc would be greatly appreciated

Kind Regards

R