[jonnoshore]

Vigoon,

I plan to build some with these... http://monacor.co.uk/products/speakerbuilding-hifi6-9/vnr/105370/

Thread here:
http://www.audiocircle.com/index.php?topic=105117.0

Well I just got a second hand bass guitar cabinet for £90 and have the empty cabinet back on ebay so got 4 12 inch beta 250W bass drive units for £20 each so far bargain... The auction ends tomorrow so they may be cheaper ! lol

I have 4 of the full drive units so plan to do a inverted pair per side, maybe magnet mounted...

[Vigoon]

The Monacor Sp-200x are excellent speakers for use in OB, as far as I know...Due to the frequency decrease over 15kHz, I do not know if a small filter is needed in OB use...
The mounting of 2 Monacor SP-130x/8 is very ingenious as it compensate the increase of the high frequencies in the open baffle mounting.
I regret that I have no electrical knowledges...This is what I understood from a very nice website in french (you can use an online translator):

http://petoindominique.fr/php/planspirale.php

At last, here is the open baffle I built using the indications on this topic...




I Understand a an open U design is more efficientin the reproduction of the low frequencies...It works great!!! Thank you very much, Scorpion!!!!

[jonnoshore]

Well I've just got myself a S/H Behringer DCX2496 Ultradrive from an auction site so I am now ready to start playing... when it arrives...

I was following the naked drive unit thread on DIY audio and may start with hanging the 200x's... I think I will need to place the Betas in an H baffle but will see what the sound brings when I start playing..

Vigoon how do they sound?

Budget so far:

£30 for 4 FR drive units
£75 for 4 Eminence Beta units once the cabinet sold
£161 for the Behringer DCX2496 Ultradrive

I have an Ion Obelisk 3 and 3X/XPac1 amplifiers which will do the duty if enough power

Some scrap wood in the shed will be called into action...
but I may use "dendro-light" for the H baffle enclosure...
Saw it at the Eco build show...

[Vigoon]

The Vols OB using Visaton BG13 8P instead of Monacor SP-130/X8 sound great!!!

[scorpion]

Vigoon,

Very nice baffles. Electrically The Visaton BG13 8P is almost identical to the Monacor units. I would expect my design to be rather spot on.
If the brightness peak (4-6 kHz) is there in real existence I suppose a little off axis listening will be better. The Germans certainly
would have designed a notch filter to cure it. But for the money I will expect outstanding performance as I also see superb Obbligato capacitors. 

/Erling

[Vigoon]

You are right, Scorpion, even they do not have 200 hours listening, those OB are great...I was just wondering how far it would be possible to go with the same design, replacing the 38cm AR 1524 with AR 1525 Neodym and using Tang Band W8-1808...A filter will be necessary to reduce the brightness in the treble, but how much and from which frequency? For awhile, I thought it would be fun to reduce the size of this baffle, but I realized it would be to the price of a dramatic loss of bass...

[jacozz]

Vigoon.
I don't think that the A&D 1525 is worth the Xtra money. Is 1mm of Xmax really worth that xtra cash? Especially since you already have the 1524.
If I was you, I would instead invest in a couple of active sub-amps. Preferably with built-in EQ.

Regarding the Tangbands. I can really recommend them. I use the 1772:s (similar drivers) and I think they are the best full rangers I have heard so far, especially when you crank them up a bit. They don't have that typical full range shout that a lot of fostex:s and the horrible Visaton B200 has. With that said, I never heard the drivers (SP-130x/8) you currently using, but personally I would be worried about the loobing effect with two drivers covering the treble, but maybe they work ok in your application.

My two eurocents.

[Vigoon]

Well Jacozz, I think you are right...The AR 1524 sound really good, so the improvement should not be on that side. The sound of this open baffle is with the Visaton BG13 P8 is really good even in treble reproduction...
As I have given this pair of loudspeaker to a friend who absolutely wanted them, I'm now willing to make another pair for myself, even better, hence the choice of the TangBand...It seems they are really good: I can only find positive comments about them on the net. Needless to say I'm really excited to try them...

[Sunyang]

Scorpion: thank you very much for your OB inspiration. You recommended R1524 looks very good. Let me ask you, what about R1830? Fs has lower (33.8Hz) and Qts is still high 0.64.