Open Baffle project

[JamieMcC]

Ok please bear with me as this project has snuck up unexpectedly on me the closest I’ve ever been to OB speakers is follow a project or two or three over the net and until very recently trying open baffle speakers myself has never crossed my mind.

This changed last week with the opportunity to acquire a matched pair of Bastani Mandella 12 inch 100dB full bandwidth drivers for the princely sum of £190 (the UK dealer is selling of the last of his stock) these ones are ex demo, barely used and well short of the 200hrs recommend run in time and I’m eagerly awaiting their arrival.

It’s a bit of a crazy thing to do on my part as I really don’t have the room for them and I have been very happy with the Fostex FX120 and BH Sex combo.  So the aim to start with is to hopefully put together something basic that performance wise is going to be pleasing that might grow with me as both my knowledge, circumstance and equipment changes (I’m looking at you Mr Kiaju).

My next step is to look for a tweeter with some finesse to complement the 12” Bastani drivers, something that’s not going to break the bank and I am hoping to find some suggestions from Bottleheads who have trodden this path before.

I really would be eternally grateful if anyone can spare a few minuets to share some of their own experiences and knowledge on such projects.

Thanks
Jamie

 

[Zimmer64]

Here are a couple of starting points:

http://www.quarter-wave.com/OBs/OB_Theory.html

http://www.dipolplus.de/downloads/Open%20baffle%201.pdf

http://www.firstwatt.com/pdf/art_slob.pdf

I've also built a few including one with the FX120, but settled now on a three way, tri amped fully active design. The others did not cut it for me:

https://zimmer64.wordpress.com/category/speakers/

Enjoy and happy new year!

Michael

 

[JamieMcC]

Hi Michael & Happy New Year

I was hoping you might reply having found your blog while reading up on the Neo3 tweeters a few days earlier and the additional information from your links has made for an interesting and educational read.

Cheers
Jamie

 

[JamieMcC]

Hi Michael

I ended up going with the Vifa h26tg35-06 tweeter this was recommended by someone who has the same driver and Vifa OB set up they have also been very helpful sharing their crossover info and have made some temporary mdf baffles up to get started with. I fired them up for the first time today using my 2W Sex amp and have been trying out some different crossover configurations this afternoon (just by ear). I know its early days configuring and positioning wise and I've still to get my active sub up and running but even so they have already impressed the hell out of me and I'm really looking forward to experimenting and getting them better dialled in.

Cheers
Jamie

 

[adeep42]

Nice. They look great. I'm sure they sound great.

 

[Zimmer64]

Nice. Enjoy the open baffle sound! After an initial modeling with Martin King's Mathcad templates, I used REW and a UMIK-1 to find my initial crossover point and then tweaked by ear and measured more.

Kind regards

Michael

 

[JamieMcC]

Little up date

A while back I added a pair of 15" Eminence Alph15A subs these are crossed at 200 Hz its fair to say the sound is off the scale the bastanis 12" drivers are just insanely good. The only real issue is they are just to big for my room so I'm thinking with a heavy heart about final enclosures and maybe down sizing to a from the 15" bass driver to a 12" to make them a little easier to live with.

Trying out some different configurations

 

[JamieMcC]

Up she rises for little update


I've had a lot of fun and learnt a bit experimenting with these speakers over the last couple of years. Recently I had the chance to pick up another pair of Bastanis Mandala 12" crystal drivers again which meant a bit of a reconfiguration was require one sheet of 19mm (three quarter inch) mdf and a metre (three and a bit feet) of leatherette added to keep the wife happy and I'm up and running again.


At 100dbish while they sound reasonably ok using just my Sex the sonics noticably improve if I just use the Sex to drive the top half and a seperate amp the 15" bass. Plenty of fun tweeking still to come I think.

 

[Zimmer64]

Jamie,

Thank you for the update. My OB set is still the same. Did not have the itch to swap something out.

Michael

 

[JamieMcC]

Hi Michael

I have really enjoyed the single Mandala driver baffle over the last two years its had a number of crossover configurations during that time. But having two Mandala drivers has brought a nice improvement. Still have a few amps in the house to try with them at some point.

Thanks for posting your build online it was certainly an inspiration.

Jamie