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Hello All,
So I have purchased one of these monsters to replace my rel classic 98. Currently I am using it without enclosre behind my gear btween my main speakers, ( Altec clones). Driving it with the Rel plate amp (removed the Rel driver and hooked up the Fostex). This sounds very very good. I have been given suggestions for a couple other plate amps , JL audio and one other I can't remember.
I also am considering getting a Marchand two way active and just low pass the sub and keep the passive networks on the Altecs ( they are currently first order) and I'm quite happy with them. If I go this route I'd like to drive them with a pp tube , maybe a kt 88 or something .
Thoughts??Thanks K
Edits: 08/02/24Follow Ups:
Hi
Driving it is not a real issue but what to do with the driver might be.
The T&S parameters for an fW800 are at the link below. I couldn't find an 880. These would let you model the response for what ever box you want before building.
A Qt of .69 at Fs of 25Hz, suggests a an infinite baffle (very large box volume) would turn this into a monster. IF you had a closet you could use or could take advantage of an adjacent room for a back volume, that would give you in room response pretty flat well below 25Hz!
https://www.madisoundspeakerstore.com/approx-31-woofers/fostex-fw800hs-31.5-super-woofer/
To put some numbers on it, Vas = 1500 liters (53 cubic feet) and will get you down to 35Hz at QT = 1.0. The suggested minimum 500 liters gives a 3dB peak at 50Hz, falling off below that.
The frequency response graph shows another +5dB resonance peak at 50Hz, but that may be a measurement anomaly.
That's what i was getting at indirectly, a qt of .69 in very close to maximally flat already, raising the resonance raises the Q as well so like the response curve shown, is under-damped.IF one could use an adjacent room as the back volume, then not only would the drivers response go lower but would no doubt tie into the room gain slope that low too, potentially extending the low corner another octave or more for free.
edit;
If one had an amplifier that had an output impedance adjustment like some "old days" amps had, like one at Grommes back then, one could adjust the output impedance either positive or negative. Making it positive gives the woofer a higher Q but negative output impedance makes the woofer have a lower Q.
More important back then to accommodate different size cabinets, before one could design based on the driver's T&S parameters.
Edits: 08/12/24
Hi I have lots of experience with these products but it's too much to write in a post
You can pm me and I will give you my telephone number and discuss
Have fun
Silence is golden duct tape is silver
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