I am in the process of researching options for my next speaker build. I have settled a bit on the idea of doing an open baffle/dipole design for ribbon mid and tweet that will be based on the design parameters of the ACR Isostatic RP200 which uses same mid/tweet as rp9 that I have. I have a feeling I may prefer sound of a sealed enclosure for the woofers. If the woofers I chose would work best in a ported enclosure, so be it.
Here is what I am working with currently.
I purchased the Fostex RP9 speakers at swap meet for 30 bucks. They appear to be brand new in the box, so using the mid and tweet will possibly save me money in the long run for total cost of components. The woofers were not usable due to age and some cone damage (Fostex use to be close to where I live, and I have a suspicion these were refurbished or new old stock someone got when they closed down). I will need to find other woofers.
The tweeter is of unknown model number. I have a suspicion it is an ft7rp without the front bezel or faceplate, possibly. It is a super tweeter.
The midrange is the fs21rp.
DESIGN GOALS:
My current idea is to make an open baffle that will hold the mid and tweet above the woofer enclosure. I am listening to them with original 3-way 1st order crossover and the upper high midrange is a tad overbearing (as shown by peak in fs21rp response graph I will post below). I hope a good crossover may alleviate this
I took out the bad woofer, and am using a woofer in it's place that is not working well but is better than nothing.
I would like to stay as close to RP200 or other rp series designs as possible, as they use the same midrange tweeter combination and I have some of the design parameters and crossover points making my possible crossover points and woofer selection a littie easier. I like the idea of dual 8", or maybe dual 10". Slender and tall speaker.
I would like to go active crossover in future for all crossover points I may use with exception of tweet to mid. I think it will make amplification easier for my first time in active crossover foray.
I would like to crossover the dual woofers to 80 hz, or possibly 100 hz depending on woofers chosen (as my receiver has built in crossover point here). I feel that going with seperate large powered subwoofer(s) may allow for a little punchier bass yet more clarity from speakers?
The RP series all crossover the tweet and mid at around 700 and 5000. If they also have the 12 inch, it is crossed over at 150 hz!!!! I would like to use these values since they seem to be decent speakers and they know how to design Unless you see a better idea from graphs attatched.
I am not stuck on woofer selection so if you look at the attatched pics and info, please share your ideas. I would like the woofers to stay Fostex if possible, just to make the project closer to RP series original design.
Please note that the 12" used in the higher RP models is still available new. The 8 inch woofer and the 7 inch are not. Have not looked for a 10 inch as Madisound does not carry a Fostex 10" (Not that I have to buy from them, just easy reference for me).
I am open to the idea of going completely open baffled, but this will make the project more likely to happen at a later date due to me wanting EQ and active xo's. Not to mention I would need more help in designing since I am completely new to open baffle designs!!!! I still think sealed woofers may be my best bet for starting out as a beginner. For a little more SPL.
I also need to figure out if I can just put the mid and tweeter on front of baffle, or if mounting from behind with nice chamfer or bezel would sound better.
I also wonder if a waveguide would work with ribbons? If anyone thinks so and can help me work on some designs, I would be grateful
See attached pics for Ribbon waveguide idea
On with the pics and stats for ideas.
First picture is of the rp9 that I got. It has an 8 inch woofer for scale reference...
The rest are RP series pictures I found online.
I also threw in a couple of other pictures I found interesting, although using different ribbons altogether.
Here are a couple of interesting links. The first link has full stats for the fs21-rp.
Fostex FS21RP
I don't know german. But the numbers and graphs I CAN read hahaha.
Here are some pictures and a little info on the RP series.
Magnat Sound-Studio 1979 - 1990
Sorry for long post. Just getting some thoughts I am having out there to see if anyone may be able to help at all.
Thanks for your time.
Todd
Here is what I am working with currently.
I purchased the Fostex RP9 speakers at swap meet for 30 bucks. They appear to be brand new in the box, so using the mid and tweet will possibly save me money in the long run for total cost of components. The woofers were not usable due to age and some cone damage (Fostex use to be close to where I live, and I have a suspicion these were refurbished or new old stock someone got when they closed down). I will need to find other woofers.
The tweeter is of unknown model number. I have a suspicion it is an ft7rp without the front bezel or faceplate, possibly. It is a super tweeter.
The midrange is the fs21rp.
DESIGN GOALS:
My current idea is to make an open baffle that will hold the mid and tweet above the woofer enclosure. I am listening to them with original 3-way 1st order crossover and the upper high midrange is a tad overbearing (as shown by peak in fs21rp response graph I will post below). I hope a good crossover may alleviate this
I took out the bad woofer, and am using a woofer in it's place that is not working well but is better than nothing.I would like to stay as close to RP200 or other rp series designs as possible, as they use the same midrange tweeter combination and I have some of the design parameters and crossover points making my possible crossover points and woofer selection a littie easier. I like the idea of dual 8", or maybe dual 10". Slender and tall speaker.
I would like to go active crossover in future for all crossover points I may use with exception of tweet to mid. I think it will make amplification easier for my first time in active crossover foray.
I would like to crossover the dual woofers to 80 hz, or possibly 100 hz depending on woofers chosen (as my receiver has built in crossover point here). I feel that going with seperate large powered subwoofer(s) may allow for a little punchier bass yet more clarity from speakers?
The RP series all crossover the tweet and mid at around 700 and 5000. If they also have the 12 inch, it is crossed over at 150 hz!!!! I would like to use these values since they seem to be decent speakers and they know how to design
Unless you see a better idea from graphs attatched.I am not stuck on woofer selection so if you look at the attatched pics and info, please share your ideas. I would like the woofers to stay Fostex if possible, just to make the project closer to RP series original design.
Please note that the 12" used in the higher RP models is still available new. The 8 inch woofer and the 7 inch are not. Have not looked for a 10 inch as Madisound does not carry a Fostex 10" (Not that I have to buy from them, just easy reference for me).
I am open to the idea of going completely open baffled, but this will make the project more likely to happen at a later date due to me wanting EQ and active xo's. Not to mention I would need more help in designing since I am completely new to open baffle designs!!!! I still think sealed woofers may be my best bet for starting out as a beginner. For a little more SPL.
I also need to figure out if I can just put the mid and tweeter on front of baffle, or if mounting from behind with nice chamfer or bezel would sound better.
I also wonder if a waveguide would work with ribbons? If anyone thinks so and can help me work on some designs, I would be grateful
See attached pics for Ribbon waveguide idea
On with the pics and stats for ideas.
First picture is of the rp9 that I got. It has an 8 inch woofer for scale reference...
The rest are RP series pictures I found online.
I also threw in a couple of other pictures I found interesting, although using different ribbons altogether.
Here are a couple of interesting links. The first link has full stats for the fs21-rp.
Fostex FS21RP
I don't know german. But the numbers and graphs I CAN read hahaha.
Here are some pictures and a little info on the RP series.
Magnat Sound-Studio 1979 - 1990
Sorry for long post. Just getting some thoughts I am having out there to see if anyone may be able to help at all.
Thanks for your time.
Todd
