want to build a DIY ribbon, need suggestions

[thadman]

I am building a DIY ribbon this summer and would like some suggestions as there isnt much information out there (other than the few informative threads on here)

I'd like to build a ribbon that rivals the LCY 130 (horizontal and vertical dispersion) and a ribbon that is able to be crossed over comfortably with an 8

I'd like this to be a no-bars held project (ideal ribbon design, no compromises), as I have full access to CNCs, lathes and the like

[thadman]

I have several connections and all of the magnets I recieve will be completely free...so the design is really open ended.

[LineSource]

Hi thadman,

The DIY archives contain all the technical info you should need, with many well documented examples and helpful websites. You could proabably spend a week studying this material. You may want to give some consideration to a long ribbon linesource during your study.

Downloading the FEMM magnetic field simulation program will be valuable if you want to do a unique design instead of a clone.

N50 grade magnets are near the highest production stength. BIG is good.

Thin aluminum foil between 5 to 10 microns is commonly used by most DIY'ers.

[thadman]

I've spent a week or so searching over the forums for diy ribbons and have learned a great deal, that is mainly why im attempting to build my own.

Do longer ribbons have any difficulty producing the higher frequencies?

Would I have issues if I ran the ribbons dipole and the midbass-midrange (50-1000/1200) monopole?

Is there any optimal ribbon width or length where you start to meet diminishing returns?

Is the main goal of a ribbon to create the most powerful uniform magnetic presence in the gap?

[thadman]

I have to check with my distributor, but the highest ive found was N55.

Is there any benefit to using below 5 micron aluminum (I know LCY uses 6 micron and an average aluminum wrapper is around 15 micron)? Are there any other types of material that are good, light weight conductors that are candidates for ribbon use?

[LineSource]

>>Do longer ribbons have any difficulty producing the higher frequencies?

A small area ribbon is capable of producing the highest frequencies, well over 50Khz, but you may need to add a waveguide or horn to get the room SPL you desire. A well designed long tweeter ribbon can easily reach 30Khz with well over 110db SPL in most rooms. I've posted the simple equations for ribbon efficiency several times in the archieves.

>>Would I have issues if I ran the ribbons dipole and the midbass-midrange (50-1000/1200) monopole?

I favor running the tweeter ribbon as a monopole to reduce short delay reflections that can "falsify" the sound stage. Dipole designers like Linkwitz also favor monopole tweeters. A monopole ribbon tweeter requires extensive absorption material in the rear cavity. Some like the "spacious" presentation of a dipole tweeter. Some describe dipole sound as "you are there" to explain the synthetic ambiance from upper fequency rear reflections. "They are here" is a pharse often used to describe the performer centric soundstage of a good monopole speaker. Some claim that dipoles offer more degree of room tuning than monopoles. Dipole vs. monopole midrange/midbass is like religion.. you will have to try both and decide for yourself.

>>Is there any optimal ribbon width or length where you start to meet diminishing returns?

The ribbon width will set the upper frequency both as the wavelength approaches the ribbon width, and because wider width adds mass while the gap magnetic field goes down.. a squared affect. There are equations to determine the minimum ribbon volume sweep to generate the desired SPL in your room. A full floor-to-ceiling is the other extreme.

>>Is the main goal of a ribbon to create the most powerful uniform magnetic presence in the gap?

The main goal of the motor design is to create the most powerful and uniform magnetic field in the gap. One can experiment with many different ribbon construction options to get the pharsing they like best. Just like two musical instruments.

>>Is there any benefit to using below 5 micron aluminum (I know LCY uses 6 micron and an average aluminum wrapper is around 15 micron)? Are there any other types of material that are good, light weight conductors that are candidates for ribbon use?

Ribbon efficiency increases with lower mass, but AL foil below 5 microns if very fragile. Magnapan uses a 2-2.5u tweeter ribbon which is 0.2" wide. You can read AudioAsylum notes to judge how robust it is.

The archives describe mylar-aluminum ribbons which some find smoother sounding and more robust. You can get aluminum sputtered onto mylar or polyimide(take a capacitor apart), or glue AL to mylar as described in the archives.

[thadman]

how efficient would an 8 foot ribbon be?

Im considering doing 2 ribbons for a 2-way

1 8 foot .25" ribbon (upper frequencies)
+
1 8 foot 2" ribbon (I'd like to get to 100-200hz with this)

Where could I purchase Mylar Aluminum ribbon?

[LineSource]

>>how efficient would an 8 foot ribbon be?

The simple ribbon efficiency equations have been posted several times in the archieves. For a tweeter where excursion is not an issue:

A=ribbon area meter^2
B=magnetic field in Telsa
%= percent of ribbon which conducts current(100=100%)
m= mass of ribbon in grams
Efficiency = A^2 * B^2 * % / m
spl 112.2 + 10*(LOG(efficiency)/LOG(10))
senS effeciency + LOG(8/resistance)/LOG(10)


>>8 foot 2" ribbon (I'd like to get to 100-200hz with this)

For a +/- 0.1" maximum excursion a monopole ribbon would reach max SPL of 110db at 420 Hz. A dipole ribbon would reach max SPL of 110db at 320Hz. The original Full Range Apogee speakers had a 2" wide x 84" long midrange ribbon that was crossed at 320Hz to the bass panel.

>>Where could I purchase Mylar Aluminum ribbon?

Check the archieves.. especially Swedish ribbon, and take apart a film/foil capacitor.

All the info you need to clone these ribbons is in the archieves. The FEMM program will allow you to create a unique design, or optimize the iron-magnet motor circuit

[thadman]

how bad is the horizontal dispersion of a 2" wide ribbon?

[LineSource]

>>how bad is the horizontal dispersion of a 2" wide ribbon?

2" is a wavelength of ~ 6,775 Hz. There should be very little beaming if you cross a 2" ribbon below 3,385 Hz, AND have a well designed front bezel or waveguide to remove pole edge diffraction, plus large radius cabinet corners.

The design of the pole pieces, rear cavity, absorption material, front bezel/waveguide will have a large affect on the on-axis as well as off-axis sound stage.