Another DIY Ribbon thread

[JAMESBOS]

Hello Tinititus,
Whats the maximum height in your loft? I have built a pair of full range planars sized 21" x 24" x 3" I'm sure these would fit in your loft. These use about 500 neos 50 x 12.7 x 3mm for the pair. These are full range so you don't have to build anymore speakers or add other coned speakers for the bass. Just a thought, also these are very easy to build and not very heavy about 5 kgs. each. Regards Henry.

[fperra]

Any progress report?

[JAMESBOS]

Jamesbos here , magnets arrived , started on the other 4' x 2 x 3" planar yesterday. Magnets in place 525. Only 2 blood blisters, this time. Cutting rubish bag today , mark position of magnets, then put the tape on plastic , hope to fit today with no tears fingers crossed, this is the hardest part you have to be very careful, rip the tape and you have to start again on the 74 rows .If all goes well will finish speaker in a couple of days!! Then I can listen to the pair using the Quad 11's I have just purchased .Plenty of sensitivity so will have plenty in reserve(watts). That's all for now Regards Henry.

[chalkandtalk]

Hi Henry,
I think I understand how you speakers are constructed. However, where are the wires connected to the foil?

cheers

Aidan

[JAMESBOS]

Hi, Chalkandtalk,
You fix the foil with screw and washer, trap the foil under then use nut to tighten then another nut to hold ring termina for cable, have finished the other 4' x 2' x 3" to make a pair. Sound great and quite sensitive. Have started on my 61/2' x 21" large panel full ranger, just putting the magnets on. Should have all on today 910 on each panel. The harder part will be sticking the tape on without tearing it!! Shold sound great and be very sensitive, plenty of umphh in reserve. Regards Henry

[chalkandtalk]

Henry,

Do you connect one wire at the bottom and the other at the top of the aluminium sheet?

Also, do you glue the magnets to the metal sheet?

cheers

Aidan

[JAMESBOS]

Hi,
It is not aluminium sheet, it is aluminium tape which you place on the membrane in one continous strip between the rows of magnets . Leave sufficient tape at each end so you can trap both ends under 2 washers held with 5mm screws, one at the top + and the other screw and washer at the bottom - impedance should be about 4 ohms if you build the 4' x 2' sized wooden surround, no need to glue the magnets. They stick like glue anyway on the perforated steel sheet. I am listening to my newly built 4' x 2' x 3" full rangers burning in my new chinese EL 34 B P/P Amp, just arrived today. Plenty of volume at the 4 ohms or 8 ohms setting. Also burning in the speakers as well. Well worth the trapped fingers and backache, the sound is so open and the bass is really tight. They are also very revealing so you need a good source and amp to drive them. Crap in and you certainly get crap out. Be very careful with the magnets they jump quite well and can trap the fingers. All the best Henry.

[chalkandtalk]

Henry, this sounds such a simple idea I must give it a go.

Would an 8' by 1.25' give the same frequency response as a 4' by 2'?

The plan
3/4" MDF for the back; wooden frame; metal sheet glued to MDF;
magnets attached to metal sheet covering an area of 8' by 1'; plastic sheet - the sort used for damp course; 30 micron alu tape from CPC stuck to plastic sheet (I'm not quite sure how you arrange to get one continuous strip); sheet stretched over frame about 3mm from magets; Loudspeaker cloth to cover plastic sheet; connect wires; voila

Does this sound right?

[chalkandtalk]

Henry,
what size magnets are you using, and where do you buy them from?

Do the magnets cover the metal sheet completely?

[JAMESBOS]

Hi, Chalkandtalk.Sounds about right although I don't glue perforated sheet to MDF. I screw it to frame. I use 50 x 12.7 x 3mm neos which you can get from www.supermagnete.de The more you buy the cheaper they are. The frequency response will be the same, but the sensitivity will be higher if you use more manets to fill the bigger cutout. You cut a hole in the MDF in the shape of a trapezoid, but you only put the mangets on top of the cutout. The tape is put across the gap between the magnets then you reverse the direction and follow the next join between the magnets, etc etc. Leaving enough at the ends to trap the ends of the tape under the screw and washers. Fixing the loudspeaker cable to the other side of the screw + and -. Just be very careful with the magnets and the tape which is easily torn. Regards Henry.