almost 25 years but couldn’t find a store reasonably close that had them back when they
were for sale in the late 80’s.
A pair of Infinity kappa 9’s .
I bought the stores last pair of kappa 8’s instead back then , I got a killer deal on them too !
But always wanted these babies .
I planned on bi-amping these before I bought them because they need a lot of hi-current
power to work right . So I was going to use my FPB 300C to run the lows and was
thinking of getting a pair of M125’s for the mid-high sections . But for the heck of it I
hooked my ST120 up on the mid-high section and I’m amazed at how well it works there
. I was sure the 60wpc from reading some would be not enough . ( It wouldn’t run the full spectrum of kappa
8’s very well at all ) . But so far they are sounding pretty good like this . So I might just
get another ST120 with the Octal board for these instead of the M125's ? I have alot of extra 6SN7’s
from the SP14 builds .
I’ve read a few posts where the designer of the speakers liked how they sounded when
run with S.S. on the lows and tubes on the mid - highs .
So. Questions #1 I've read when biamping , the amps should have the same or at least close
input sensitivity - gain to work right so you are not driving one or other other amp and
speakers to much ?
So the ST120 needs 1-1.25v. to drive the amp to 60 wpc and the FPB needs 2.35v to
drive it to 300 wpc . Full volumes .
Since my ST120 dosen’t have the attenuator in it could I just build like a passive
“preamp” with just an attenuator and a pair of inputs and outputs and put it in at the
outputs of my SP14 before the ST120 to turn the gain down before it gets to the amp so it
doesn’t top out before the FPB does ? Would that work ? Also is there a easy way to
measure the output voltage of the preamp so I could match the input voltages close ?
The way it is now the top end does sound like it gets louder faster with the volume . And
the bass is a little weaker than I think it should be . I think it should sound right once the
input bias are matched to the amps . But they still sound good . I don’t want to crank it up yet
and hurt anything .
Question #2 . How do the ST120’s hold up to some brief 2 ohm loads ? The speakers are
rated at 4 ohms but they briefly dip down to 1-2 ohms at one frequency on the top and on
the bottom . I don't normally listen to music real loud but I will sometimes crank it up when
no one else is home .
The Speakers when I got them were WOOPED ! I wish I would have heard them in my
system before I bought them ! He had them hooked up to a little crappy reciever when I
auditioned them and couldn’t properly power them. I might not have bought them !
The grille cloth looked like they housed a moth collany for ten years. At least I knew that
before I bought them though . And the cases had some little water damage to them . But
when I got them home and hooked them to my system I heard some dissapointing
sounds coming from them . The woofers were supposedly refoamed but one voice coil
was seriously scrapeing and the foams were comeing loose at the glue and two dust cups
smashed in and crackaling ! One of the low tweeters was buzzing , the two high tweeters
were not working at all , and the rear tweeters were working very poorly. OH ! and
whoever reinstalled the woofers wired them wrong! In parallel instead of series .
Needless to say the bass was almost non existant . So after three weeks of messing
around waiting for caps and foam kits . Two grill re-cloths , two oak case repairs ,one
used woofer ,four woofer refoams ,voice coil re-centers and all new dustcaps . One new
(used) low tweeter , one high tweeter and complete crossover re-caps they are sounding
and looking ALOT better . I did get them for a decent price though, but I had to put alot
into them to get them sounding right .
Man the crossovers were a pain . Alot going on in there . Alot of hot glue and non standard cap values .
Not dynaco but ...
Thanks to some info here and Building my ST-SP & PH builds I was able to figure out what was wrong with these monsters . A couple years ago i would never have even attempted it . There was a total of 6 bad or very out of spec capacitors in both crossovers . From my research reading the electrolytics usually go out of spec from age and the film Solons usually stay good . But it was just the opposite on these , the Electrolytics all checked in spec and all the bad caps were the Solons. One of the 3uf caps actually read .02uf . Figures since I replaced the films with new Solons since I didn't want to spend what the Sonicaps would have cost !!
I have to find a place to put the ST120 now .
Kappa 9's on left 8's on right .