Fluid Audio Group

Good Day!

My name is Alain Benoit.

I currently own a tube amp repair shop. I do custom builds, mods and general service work. I also operate rehearsal spaces.

For over ten years I owned a commercial recording facility. See link here; www.fluidaudiogroup.com

I have been doing live sound in both FOH and Monitor capacities for over 25 years. Although I mainly toy with PA for fun nowadays.
See recent entry in PA of the Day here; www.paoftheday.com/shop-system-featuring...x-tannoy-crown-gear/

The reason I am here and my plan over the winter is to convert two pairs of double 18's I have into 8 single 18's. The reason for doing this is that the current cabinets are in poor condition and the others are a little more pragmatic, portability and scale-ability.

The first pair of cabinets are Electro Voice Eliminator 2 x 18 loaded with B&C 18/029-4 which are the OEM part for Yorkville LS 800/900 series front loaded subs. These are ceramic magnet drivers. Naturally B&C nor Yorkville will release the TS parameters of these drivers to me but deductions can be made.

The other pair are Chinese copies of JBL SRX-728, I got these for very little money, the boxes are plain MDF that are barely braced and had to be re-glued on arrival, since then they have been working fine but I do not wish to ever move them. The drivers in them are assumed to also be a Chinese re-creation of a B&C driver, no way to know the parameters of these. On a good note, they have been taking a weekly punishment from a Crown XTi 6000 for two years now with no signs of failure.

My knowledge of acoustics and cabinet design are weak but my knowledge of electrical/electronics and power amplifiers are not.

My question is, given this limited information, what would be the optimal sub design for the drivers on hand from your menu? Cubo 18's?

See attached pictures and link.



Thank you all in advance for any help or insight provided.

A.

Good day to you too!

Well, Cubo 18's are a pretty safe bet, because if a loudspeaker works in the Eliminator, the Yorkies or the SRX-728 it's safe to assume it works in Cubo 18. However looking at the plans I suppose they would also work in the majority of the front loaded horns (some of which are port assisted) or the Mini Scoopers, as the L800's are also mini scoops.

You could even build a few prototypes from MDF of different choices of cabinets (say a Cubo 18 Extended, the Mini Scoop and one of the many cabinets starting with an M and ending with a number), to get familiar with building cabinets, test them and then build 8 of whichever you like best.
Personally, if the low end is of most importance I would go with a Cubo 18 and if it's going to be used over 100 - 120 Hz I would go with a front loaded horn.

Best regards

Cubo

Thank you kindly, your reply confirms my assumptions.

I will proceed with building a prototype MDF Cubo 18 and report back.
My girlfriend is a cabinet maker by trade and has lots of MDF in the shop, she will be taking the lead on the actual cutting and assembly.
What are the alternates to "T Nuts" when using MDF?

I had omitted to state the operating range, 35hZ to 100Hz give or take is what I am aiming at. That being said, Cubo 18 extended or regular?

Thanks again for your time.

A.

I almost always use t-nuts when building MDF prototypes, however I almost always use a bit of glue between the t-nut and the MDF (never failed to date), either epoxy or Bison Tix contact glue (from a tube for greatest ease). Without the glue it's whole other story, in which case you could use insert nut's ( en.wikipedia.org/wiki/Insert_nut ). Though personally I'do only use insert nuts when I can't reach the baffle from the rear and tend to hold the insert nuts in place with epoxy or polyester.

As being said, Cubo 18 Extended

Best regards

Cubo