Fostex RP9 swapmeet find. Need info!

[TMHutson]

Howdy. Todd here.
I was at a swapmeet, and saw a pair of speakers that were in individual shipping boxes, and one speaker with no shipping box that was smashed up and missing woofer. I noticed that the speakers were Fostex, and had ribbon tweeters and ribbon mid-ranges!
The lady wanted 15 dollars for each one. I didn't want to unwrap the plastic and mess with them. They seemed to have a funky little 3-way crossover box with them (simple 1st order?) which said "for rp-7 or rp-9". It looked to be missing parts, so I just moved on.
Well, I had already been stewing on some speaker projects and lurking on this (and other) audio/DIY websites. I decided to go back today with a double A battery to test the drivers. I opened up the boxes, and took the speakers out completely. I plugged in the crossover network to speaker wire harness (pictures show proprietary Molex style plugs for the crossover and speakers). Then I touched the battery to the crossover input and only the mid-range worked. The woofers did not work, as their surrounds are trashed and coils may have been blown. I then disconnected the crossover network and tested each speaker at the Molex plug. The mid-range and tweeter sounded good to me I was happy that the broken third speaker was there, as the grille was trashed and I could see the mid-range and tweeter up close. The grilles are glued on, and I have to rip them off to take out woofers
They are now in my possession. I just took some pictures to share with people and see if ANYONE has ANY info on these. I don't know where to get specs for the ribbon units, or the speakers as a whole. They seem somewhat old (80's?) and I cannot find a single iota of information on the interwebz. I also had to tear grilles off, as they are glued on. I took one picture with grille on so you can see what it looks like.
I have strong basic knowledge of speaker design. I have custom built more subwoofer boxes than I can count, including 4th order bandpass, many sealed, and few ported. I have built simple passive crossover networks (2-way, different orders). I have built speakers from well designed kits with entry level speakers.
I was thinking these drivers could be used for a fun project. Alas, I have limited experience with ribbons, and also no specs to start with. No testing equipment at all.
I am in SoCal LA area, so if anyone has some cool ideas for me to start with as far as making custom enclosure, and maybe a quality crossover network... I would greatly appreciate it.
This is my first post, so sorry it's sooooo long. But I enjoy telling stories, and you can never have too much info

Well.. Here are some photos.
By the way, the crossover says 4ohm, and the woofer says 4ohm...

If the photos do not work, it is because I could not find a test forum on this website for checking to see if I am doing it right. I am new to this site, but not to forums in general :P







The back of the cabinet has threaded bolt holes. I have no clue what this would bolt to! Can't put it on a solid wall, as you would not have access to nuts! Maybe it was put on a board, then in wall as infinite baffle? I don't see any felt or type of sealer for woofer baffle where it might attach to a box. They barely stand on thier own, so they are most definitely not OB speakers The panel appears to be made of some composite. The woofer has decent basket and magnet. Woofer on one of these is not good, as some dork pushed thier fingers in from behind. Surrounds are totally trashed as expected. I have no intentions of fixing the woofers, or using original panel with new woofer. This will be a "from scratch" project to help me learn more about crossovers, and different baffle options

Since the crossover is 4 ohm, I was considering using an 8" Infinity Beta series car woofer I have, and put it in a small sealed enclosure. Make a panel for the mid and tweeter drivers, and place on top of box to see what happens. This crossover network looks very small. Like something you would get with a cheap set of car audio components I am going to open them up... Don't need the cover, anyhow. If anyone needs to see a picture of crossover, I will take a picture.

Thanks for your time. I appreciate it. Any input or ideas are welcomed. I am hoping I did not waste 30 bucks on these I will experiment with them tonight and tomorrow.

Todd

[planet10]

The tweeters are likely a variation on these... 100mm Ribbon Tweeter BARGAIN! - Jaycar Electronics. If they work they are worth the entry.

If the midranges work they are worth more.

Is it just the surrounds on the woofers gone? If yes, well worth spending another $30 and getting a set of new surrounds.

dave

[TMHutson]

One of the woofers looks as if it can be fixed. The other woofer has crack in the edge of cone due to swap meet people fiddling with it The woofers seem to be rigid, yet very light. Possibly carbon fiber, or some composite interwoven material. You can see light through the cones, they look like little dots where the light goes through. They have what appears to be a cast aluminum basket. My Infinity Beta woofers are high quality, and these look to be a step up! The magnet is huge, and has what looks like a 3 inch voicecoil, or bigger! But not worth fixing, in my opinion... Not with one woofer being cracked.
I leaned my Infinity Beta 8 woofers against panel and hooked it up to crossover. Due to no direct contact with baffle (almost 3/4 of an inch gap due to basket mounting plate being different shape), and the woofer being designed for a sealed cabinet, there is NO mid-bass as I expected. But with my sub crossover cranked as high as it will go, it is making it easier to tolerate the sound. When I have the money to buy wood, I will make a small cabinet (.2 cubic feet for flat response, .4 for enhanced response) for the woofers. I am not accustomed to the sound of the ribbons, but it seems so detailed it would be worth messing around with.
I just got a pair of Boston Acoustics VR20's for 100 bucks on craigslist, and they sound ok for the money. I don't like the tweeters (never liked Boston tweets). The ribbon tweet and midrange on the Fostex sounds very detailed, yet a little overbearing due to no cabinet or woofer... Yet I still like the sound a lot better than the Boston!!!! Just need to find the right woofer and cabinet style to go along with this. Time to learn more stuff!!!!

I took the cross-over apart, and it is very small. The coils look pathetic and the caps are tiny But they seem to work ok for a typical 1st order...

Thanks for the info, as those tweeters do look similar. Although the tweeters on this unit do not have a rounded metal plate.

[planet10]

Originally Posted by TMHutson

Although the tweeters on this unit do not have a rounded metal plate.

That is just the bezel for mounting it on the baffle, it is the rest of it that is important.

dave

[TMHutson]

This first picture shown below is of the Fostek rp-1001 which seems to use same ribbon mid-range and tweeter combination as the RP-9 set that I have. There was another higher model with larger ribbon elements which I decided not to post.

The second and third pictures are of VMPS speakers that seem to be using the same size and possibly same make of tweeter and midrange. I put pictures of both styles to see what options I had for woofer styles and mounting.

The last 2 pictures I am too lazy to look up where I got them. But I do like the idea of a ribbon with a wave guide.

Still have not found any specific information on the older Fostex speakers. But this is a step in the right direction on figuring out what to build for my next project using these drivers... I won't know what to do with them until I know what I have. I have never owned anything with a ribbon on it.

I am using this thread to collect info on this model of speaker, and similar designs for the most part. I will start another thread when I figure out what questions to form regarding actual design options as I start working on the "project".

If anyone has seen speakers using similar driver set ups, please post pictures and details. The more information the better.

Thanks...
Todd

[TMHutson]

I was taking a closer look at the warranty card. I was initially confused by the questions they wanted filled out. They were asking the owner filling out card if they were in a car club, and what brand CAR stereo they owned. What? That is when the light went on in my head. No wonder it has such and odd design. It is for inside a vehicle. Like a pimped out shag wagon or something
I read the other side of warranty card, and it did mention the warranty only covered the product if it was "professionally" installed in the VEHICLE. Well, wha'dya know!
So, I guess this was some fancy car audio product!!! Very interesting indeed. I tested the two ribbon units, and they are 8 ohms. The woofer was 8 ohm, and the crossover said 4 ohms as well.
I still intend to dismantle this thing and make home stereo speakers with the ribbon drivers in a dipole configuration....
Should this be moved to car audio forum (maybe someone will find this old design interesting?), even though I am going to dismantle the unit? I can always start a different thread in a home audio speaker forum when I am ready to start designing the HOME speaker version of this
Thanks... Todd

[mistercooper]

Hi to you all!!! I'm from Italy and this is my 1st message on this beautiful forum.
I have both the loudspeakers (the midrange and the tweeter) mounted on the
speaker of the 1st post.
The midrange is a FS-41RP and here you are the picture of the 1 that I have

The tweeter is a FT-12RP and here you are the picture too

[TMHutson]

Thank you for helping with the part number of the tweeter. I could not find it anywhere on the net, including any pictures. Your first post was appreciated greatly for the help!
You said that you had the speaker like I showed in my first post. Where did you buy the speaker? Do you know if it was used in a car stereo application?
Also, I have a suspicion that this tweeter may be the same unit that is used in the Ft7rp, but my tweeter has no enclosure or mount. This is only a guess, as the tweeter I have matches no other smaller tweeter by Fostex that I can find a picture of online. Almost every home speaker made Fostex or other speaker manufacturers uses the FT7-RP tweeter in thier designs, some used with the FS21-RP. Being that this speaker I have is for car and has limited depth due to grille, maybe they dismantled the FT7-RP tweeter driver from it's mounting faceplate to make it fit?
You say that the tweeter you posted is called the ft12-rp but I can find no info in all my searches on the internet. As a matter of fact, your picture is only other picture I have seen of that particular tweeter! I have found limited info on many other tweeter models and mid-range models like the FS41,FS21 and FT7 in the rp series.
Are you going to make something with those drivers? If so, be sure to make a thread!
Thanks...
Todd