Help choosing an FR to use with an 8" MLTL

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Hi,
I have a pair of MLTLs (Dayton RS225 + SB29RDNC) active powered by T-amps of a miniDSP.

They are the first DIY pair of speakers I've made and love how they sound -in fact I don't have nothing more on hand to compare then with-, but I have been recently reading here about FAST and I would like to try the concept in a low budget way (let's say around USD100 /pair) and substitute the SBs with a pair of FRs.

I have some in mind, but I don't know what would be the most suited for a xover point of around 300-500. I want to try OB on FRs first, and if it does not work (mostly sure it will not becuase of short distance to rear and side walls) I will make small sealed enclosures for them.

I have bee thinking about these:
- Fostex FE83en
- Fostex FF85wk
- Fostex FE103en
- Fountek FR89ex

What do you recomend?

 
FF85wk. I love this driver. I have directly compared it to the other 3.

For this use i'd pick it over the much more expensive A10.2 which gets disqualified quickly because it is over 2x the budget.

dave

I usually do not listen loud, but 15w max did not seem a lot anyway. Should I be worried about max SPL? What do you think it would be the max SPL with an xover of 300/450/600hz on OB or sealed? Steep slope is not a problem.
 
So I understand that FF85wk would be happy HPed around 300hz (or higher) LR24/48 even OB or sealed as far as xmax and distortion goes.

I'll follow your suggestion and I'll order a pair.

I'll try them first OB in it's own baffle "dome shaped" on top of the MLTL cabinet, centered about 43" above ground, CTC distance from woofer around 8". If it does not work because of short distance from adyacend walls, then small sferical sealed cabs will be made.

I will do this test anyway, but... what do you imagine the results will be going from a 2-way XOed at 1.65kz to a FAST XOed at 300kz? Will it be a step up?
 
frugal-phile™
Joined 2001
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Our FAST MTM with these is XOed at just over 300 hz 1st order, and plays plenty loud without strain.

4th order will really extend their power handling (likely at a loss of finesse)

dave
 
Hi Dave,
can you give an idea to my last question "what do you imagine the results will be, going from a 2-way XOed at 1.65kz to a FAST XOed at 300kz? Will it be a step up?"

The FF85wk does highs as good as some much more expensive tweeters, has better mids than the 8", and with the XO moved low is both out of the critical range and driver separation at the XO is less than the wavelengths at the XO. Get them close enuff and the drivers are essentially co-incident

dave


translated from Davespeak - "yes, probably a step up"
 
frugal-phile™
Joined 2001
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It seems a win or win situation. Nice!

Just one more thing: Will it be needed a cap to protect the FR85wk from some unwanted turn on/off pop noise seeing its very low xmax?

We didn't use any but one could protect (XO in the MTM is passive, in Tysen it was PLLXO), it would need to be large & i wouldn't use anything but poly, it will degrade the sonics.

dave
 
Updates:

FF85wk are at home and have already been tested in cardboard baffles. Even not in the best conditions, I have tested them crossed from 300 to 650, from 6db to 48db, underlaped to overlaped... and did not find the magic, sound was very thin.

Something very extrange that I was not able to investigate because wife asked to remove "those ugly things on top of the speakers" after 3-4 days. Things were acceptable with female voices, but male voices seemed to come from a totally diferent speaker at a diferent timing (if this makes sense).

Drivers were not broken-in when tested, so I will do tests again in future -when job let me more free time-. Now listening again with usual configuration RS225+SB29 crossed at 1440 @ 48db and sounds much better, much bodied and less fatiguing.
 
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