Anyone have any information on the Fostex Laboratory Series T825 horn tweeter?
I've not found anything particularly useful online, hints of efficiency in the range of 102dBSpl, and that they sound good is about it.. I plan to cross at around 8kHz.
They are not quite efficient enough to keep up with my woofers and am planning eventually bi-amping mids and highs partly to get around this and for other reasons.
I've not found anything particularly useful online, hints of efficiency in the range of 102dBSpl, and that they sound good is about it.. I plan to cross at around 8kHz.
They are not quite efficient enough to keep up with my woofers and am planning eventually bi-amping mids and highs partly to get around this and for other reasons.
Here's some info clipped from a brochure of Fostex Laboratory Series components circa. 1981:
Do you have some of those on hand, or just considering acquiring them for your project? Those Lab Series drivers are kind of scarce, in my experience!
Wilf
Do you have some of those on hand, or just considering acquiring them for your project? Those Lab Series drivers are kind of scarce, in my experience!
Wilf
Hi Kevin,
I just want to ad that I used to have a pair of T825 tweeters. I used to cross them around 6k, where they sounded significantly better than the tweeter-part of the BMS 4592N 'coax' compression driver. Actually, I regretted that I sold them at some point....
Best regards
Peter
I just want to ad that I used to have a pair of T825 tweeters. I used to cross them around 6k, where they sounded significantly better than the tweeter-part of the BMS 4592N 'coax' compression driver. Actually, I regretted that I sold them at some point....
Best regards
Peter
Hi Wilf,
Yes I have them on hand and will eventually use them once I move to a bi-amp configuration. (Woofer will get its own amp, mids and tweeter will share an amp designed specifically for 200Hz - 20kHz bandwidth, a combination of active XO at ~ 700Hz and passive (spkr level) at 8kHz will be used.
Peter, thanks for the comments. Many people have told me they easily out class the JBL 075 I currently use. The JBL is 8dB more efficient than the T825, I can get a couple more dB out of the XO with some minor changes, but it will probably not be quite enough to match my woofers.
Yes I have them on hand and will eventually use them once I move to a bi-amp configuration. (Woofer will get its own amp, mids and tweeter will share an amp designed specifically for 200Hz - 20kHz bandwidth, a combination of active XO at ~ 700Hz and passive (spkr level) at 8kHz will be used.
Peter, thanks for the comments. Many people have told me they easily out class the JBL 075 I currently use. The JBL is 8dB more efficient than the T825, I can get a couple more dB out of the XO with some minor changes, but it will probably not be quite enough to match my woofers.
Old thread, I'm now tri-amped but previously ran these in a passive configuration (it turned out that they were just on the hairy edge of efficient enough to do it).
When I finally went fully active a couple of months ago, based on the Fostex specifications I set the electronic crossovers to crossover at 5kHz which I eventually concluded was too low.
Having completed my own electronic crossover design a couple of weeks ago I am now crossing at 6kHz which is significantly cleaner sounding than it was at 5kHz - this is puzzling since Fostex claimed anything over 4kHz was acceptable.
The crossovers are LR4... (24dB/Octave)
These are really nice sounding tweeters and run out to 20kHz in an actual room in actual measurements.
When I finally went fully active a couple of months ago, based on the Fostex specifications I set the electronic crossovers to crossover at 5kHz which I eventually concluded was too low.
Having completed my own electronic crossover design a couple of weeks ago I am now crossing at 6kHz which is significantly cleaner sounding than it was at 5kHz - this is puzzling since Fostex claimed anything over 4kHz was acceptable.
The crossovers are LR4... (24dB/Octave)
These are really nice sounding tweeters and run out to 20kHz in an actual room in actual measurements.
kevinkr,
If the efficiency a bit low you can sell them and get the Fostex T500amk2 tweeters. These are the next best tweeters to the TAD ET703 IMHO. I use them (TAD's) in a 4 way horn system and have tried the fostex tweeters with excellent results. I will also be getting the big Raal lazy ribbon tweeters to try. These have variable taps with efficiency up to 111db sensitivity, amorphous core transformers and was "told" that these are the best ribbon tweeters on the planet. Any one of these tweeters are world class. Good luck.
If the efficiency a bit low you can sell them and get the Fostex T500amk2 tweeters. These are the next best tweeters to the TAD ET703 IMHO. I use them (TAD's) in a 4 way horn system and have tried the fostex tweeters with excellent results. I will also be getting the big Raal lazy ribbon tweeters to try. These have variable taps with efficiency up to 111db sensitivity, amorphous core transformers and was "told" that these are the best ribbon tweeters on the planet. Any one of these tweeters are world class. Good luck.
No longer an issue since I have dedicated power amplifiers to drive them, just a gain adjustment.. One amplifier channel for each driver in the system... A better tweeter of course would be welcome, these are really nice regardless.. 😀
Measurements reveal that at the listening position uncorrected they start to roll off around 11 - 12kHz, about 3 meters out. Anyone have recent on/off axis measurements?
Crossing at 6kHz and they are at 0° relative to vertical, and I guess probably would benefit from angling downwards by a few degrees.
Last near field measurement (not today) at 30cm indicated that they just made it to 20kHz at about - 2dB or so.
I used to cross at 8kHz but determined through measurements and listening that the tweeter performs a lot better at 6kHz and up than my midrange drivers and horns.
Crossing at 6kHz and they are at 0° relative to vertical, and I guess probably would benefit from angling downwards by a few degrees.
Last near field measurement (not today) at 30cm indicated that they just made it to 20kHz at about - 2dB or so.
I used to cross at 8kHz but determined through measurements and listening that the tweeter performs a lot better at 6kHz and up than my midrange drivers and horns.
Retired recently and replaced with FaitalPro HF-10AK on STH100 horns. Apples to oranges comparison. Radial horn vs tiny tractrix and really good HF driver. Much better performance above 14kHz.