FR125s in open baffles

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Fuling

Fuling

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Joined 2001
Hello,

No matter how many times I´ve failed in building open baffle speakers that I can live with I still can´t get them out of my mind.
It seems to be true that once you have tasted OB you´ll never go back to regular boxes...

My latest attempt was a hybrid system with FE167E in 120x66cm oak baffles and SS8545 woofers in closed cabs integrated in the baffles. Sounded fairly good, but the big difference in driver efficiency called for biamping which took all the fun out of the hobby (Building amps is what I like best and I want my speakers to be compatible with every amp I build, not just my lousy four channel tube amp).
FE167E isn´t the best choice for open baffles either.

I had a little break from hifi and DIY a while ago and when I got back it wasn´t as fun as it used to be and I realised that the speakers was the problem, I couldn´t just change things in the signal chain anymore since I was stuck with my active crossover/preamp and my 4 channel amp.
The solution was to put the Fostex drivers back into their 24L BR boxes. Now I could experiment as much as I wanted with the rest of the system, but suddenly I began to miss the OB sound...:xeye:

For one reason or another I ordered a pair of CSS FR125s a couple of days ago, the idea is to build another hybrid system with them fullrangers in open baffles and a pair of Peerless 5,25" drivers in closed cabs for bass support. The sensitivity matches much better between these two drivers so hopefully I can get away with first order passive XO in the 200-300Hz range.
 
B

BHTX

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Joined 2006
I've heard that the FR125 and WR125 make great OB's, which didn't surprise me the least bit, with their highish qts. Might need a simple notch filter tho, and beaming might be an issue. But, if you're used to full range drivers, maybe it won't bug you like it would me. But yeah, good choice with the FR125's! And I think they should work pretty well with the SS8545's too. Your xo sounds about right. Despite what others have said about the FR125's performance in the lower octaves, tests will show that it'll perform it's best roughly around 400Hz and up. I can't seem to find my reference atm for that tho. Maybe I'll stumble across it later. Goodluck with your project. :)
 
Fuling

Fuling

Member
Joined 2001
I guess the XO freq. will be determined by what caps and inductors I can find i my junkbox, at least initially:)

The baffles in the first link looks pretty much like my previous ones, I used oak panels and piano hinges. I still have them around so what I will do is to move the wings over to new middle pieces. The wings are 160 and 200mm wide, and 300mm panels are also available.
I think I´ll try with just the FR125´s alone before I cut holes for the bass drivers.
 
B

BHTX

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Joined 2006
Yeah, I absolutely LOVE the over all look of the CSS FR drivers, with their copper phase plugs, against real wood panels/veneers of that color. If and when I ever give in and buy a pair to play around with (which I probably will), that's definitely the look I'll go with. And yeah, I'd wait on bass drivers too. Only possible downside is that you might end up with a little procrastination with those Peerless woofers? ;)
 
Fuling

Fuling

Member
Joined 2001
might end up with a little procrastination with those Peerless woofers?
Click to expand...

I secretly hope so:D

I had some regrets about cutting holes for the Scanspeak woofers in my latest baffles, so I´ll be careful not to do the same mistake again. Separate "sub"woofer enclosures would be an option, but the distance between the drivers versus the high XO frequency might be a problem.
The best way to know will is of course to find it out myself, so no woofers in the baffles to begin with!
 
planet10

planet10

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FR125S should work really well if XOed above at least 150 Hz... we tried them in OB 2 diyFests ago and they run out of steam far too early in the bottom.

And keep in mind that it is pretty simple to dramatically improve the FRs performance -- so much so that i don't think i'll bother selling them without that tweak.

dave
 
Fuling

Fuling

Member
Joined 2001
Well, I´m getting more and more excited about these drivers without having heard them yet!
I´ve found a fairly big sheet of plywood that will be cut in two and used as test baffles the same minute the drivers arrive, oak is too expensive to use in prototypes:)

it is pretty simple to dramatically improve the FRs performance
Click to expand...

May I ask how?
 
planet10

planet10

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Fuling said:
May I ask how?
Click to expand...

2 vanishingly thin coats of C37. At some point (i have to find bottles etc) i will probably sell little kits because the minimum amount of C37 you can buy will do many, many drivers (and costs as much as a pair)

Puzzlecoat works a bit less effectively (and if you aren't really careful can end up having you glue the voice coial to the phase plug)

dave
 
planet10

planet10

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Fuling said:
Paying >100 bucks for a bottle of C37 is not an option
Click to expand...

The reason why i am considering repackaging it... with the amount you need for a pair of FRs almostthe entire cost would be the time it takes to repackage it...

and a google search for "puzzlecoat" comes up with a lot of info about coating drivers but reveals nothing about what "puzzlecoat" really is...?
Click to expand...

http://www.t-linespeakers.org/design/tweeks.html

dave
 
TerryO

TerryO

Member
Joined 2002
planet10 said:
FR125S should work really well if XOed above at least 150 Hz... we tried them in OB 2 diyFests ago and they run out of steam far too early in the bottom.

And keep in mind that it is pretty simple to dramatically improve the FRs performance -- so much so that i don't think i'll bother selling them without that tweak.

dave
Click to expand...


Dave,

Are you talking about the pair I brought to Al Wooley's place? They certainly had problems with breakup, but I think it was amp related. Just the same, it's asking a lot from a small driver to attempt Full Range. Crossed over at 300-400HZ to a big woofer would be my choice if I were to do it again, especially in a large room.

Best Regards,
TerryO
 
planet10

planet10

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Paid Member
Fuling said:
I think I know where I can found some of this decoupage stuff for free. Where should I put it , and how much?
All over the cone, or...?
Dont wanna ruin the drivers the first thing I do, you know:)
Click to expand...

Thinned down (doesn't take much water to make it soupy)... 2 coats as thin as you can manage and still cover the main cone. I use a artists paint brush about 1-1.5 cm wide

I wouldn't mod them till you have lots of hours on them stock. They should sound "the same" but with a significantly lower noise floor after you are done. This reveals a lot of low level information which makes them seem a different driver... ie the tonal balance is the same but they have more downward dynamic range

dave
 
Fuling

Fuling

Member
Joined 2001
Ok, I think I got it. Thank you very much for your help, Dave!

BTW I got a bit bored today so I drove to the hardware store and bought two 20x120cm oak boards and a bow of screws.
When I came home I cut holes for the drivers and moved the wings from my old baffles over to the new ones and rounded the edges. Will post pictures tomorrow.
 
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