Optimus 4 speakers

[MezcalOxa]

With seat cushions, those mid/tweets scream Fostex. Anyone have/heard these? $350 asking, they do look mint ( on CL). Any thoughts appreciated. On the other hand ....must.....not......buy.....any... .more.......speakers.......

 

[z-adamson]

You only live once. If they are interesting to you, better to get them. They are actually quite nice and those do look like fostex drivers. I’d get them. Better to experience them than to be wondering what they would have been like.

 

[MezcalOxa]

That's exactly what the thumbs up smiley is saying, thank you

 

[eizner23]

Did you get a chance to sit on that cushion?!
I wonder if that Fostex was stock. I’ve only seen them with the same drivers used in Optimus 1 model.

 

[MezcalOxa]

Yes, these are the original production Fostex and cushions, later models ( 2 I think ) those look like Pioneer or Audax? And no I haven't sat on them because there is a very interesting set of Sparkomatic Altec towers on the radar. Or a set of tires for the car......or a tube amp....and OMG those Phillips 8 inch full range console pulls from CL are really sounding nice. I mean better than Lowther nice. It gets worse, Altec Valencia for a grand nearby. Waiting to for one of the HVAC repairmen here at work to toss another 30 uf paper in oil for the notch filters, it's heat pump service season here. PS I had 1 lonely Solo 20 which was fe103 with a notch filter and that thing played down into the 40's, never did find another one.

 

[JRhoBurton]

Restarting thread...

I found a pair of Optimus 4 a while back, playing now after refurb. I asked how to deal with locked up surrounds in this thread, which applies to several models:

Post in thread 'Acetone frees up surround...until it dries'

Mar 22, 2026

I think I am on the right track with the woofers. I tested one pre-treatment with DATS, and just tested both again.

Fs: dropped from 95 hz to 24.
Qts: dropped from 2.3 to 0.61
Vas: increased from 1.45 ft3 to 10.6
Sensitivity about 90 db @ 2.83v

These would work fine in a huge box at low sound levels. Probably won't do that. After I fix the tweeters I will probably end this thread and start a "Optimus 4 refurb" thread, if mods permit.

• JRhoBurton

• 

Recapped also. They sound good but need to play for a while. @Pete B was wondering if the surrounds will stay loose over time. I will check fs again after a few months. No cushions came with these.





I think these speakers would be more versatile if the 2nd tweeters had been mirrored. With woofers and "primary" tweeters aimed forward, the 2nd tweeters are both on the right side. I'm thinking about modding one to move tweeter to left side.



Crossover appears to be about 660 hz. I would call these mid-tweeters. They do have decent highs. I have not used Omnimic for a long time, maybe I will measure.