K-77 square magnet vs. round magnet tweeters

[biglaz]

Are there any signifigant differences between these drivers. I have 1 of each and would like to use these in a heresy project. Or should I hold out and try to get 2 of the same?[*-)]

[OO1]

I would most definitely wait to have an exact pair - and verify which crossover you have for your HERESY I - E or E2

- the round k77 uses an alnico magnet - the square k77 uses a ceramic magnet - the round K77 reaches I believe 14-15khz - the square up to 17khz -

-either one will give you great sound -but only a pair will result in a balanced sound - if you can post pictures of the tweeters with a DCR reading - we can give you even more details as to what you have in your hands -

[garyrc]

Klipsch used to provide individually matched pairs of tweeters -- maybe they still do in their Khorn and La Scala II speakers purchased as new pairs, but I doubt that the parts department provides matched pairs when people buy tweeters only. I was surprised that my AK4 stock upgrades for the Khorns contained K77-Fs that were very much the same according to tests I ran with a calibrated microphone and Room EQ Wizard. They were virtually identical except at the very top, where the two traces (when overlayed) departed slightly. The same model tweeter (K77-F) in my Belle (Michelle) -- which was one of the last -- is appreciably different, again chiefly above 10K. All go out to 17K and then dissappear. All use flat magnets.

In the bedroom, we have two EV T35s (once used by Klipsch as K77s, but individually selected). They are round magnets, and are very audibly different from one another, and from the K77-Fs in the house. These two happen to go out to 16K by ear (haven't measured them with REW Wizard, though, so ???).

A few years before we installed the AK4 upgrades in the Khorns, we managed to blow one (a K77-M) by not paying attention when a test disk was on, and there was no M replacement available at the time, so we installed a F. It was one of the early Fs purchased from Klipsch parts, and it got an F from us. It sounded entirely different (duller) than the M, and equally duller and different from the two new Fs that came in the AK4. I have several reasons to conclude that the Fs have improved since the first year(s) they were available. They now sound a lot like our remaining M.

Unlike many people on the forum, I really like these tweeters. IMO, they are better sounding than most tweeters I hear, including those in pretty expensive speakers.

[biglaz]

Thanks to both responders. You have helped me a great deal.[]

[OO1]

the original round K77 are a much better sounding tweeter than the later K77M or F to my own humble opinion - they do not screech as much as the newer K77 square as these do hit higher levels - sometimes a less efficient tweeter can be that much more pleasant to the ear -

-the newer gear is definitely more powerful , dont let anyone tell you otherwise - once you will have 2 exact pairs - you will be able to judge the difference on your own - take care

[seti]

Had both liked both.

[garyrc]

the original round K77 are a much better sounding tweeter than the later K77M or F to my own humble opinion - they do not screech as much as the newer K77 square as these do hit higher levels - sometimes a less efficient tweeter can be that much more pleasant to the ear -

Some of the rounds are not as bright as others ... so if matched pairs
of rounds were put in the Heritage line before Klipsch went to flat
magnets in the early 1970s, someone buying a pair back then might have
two "soft" (not bright) ones or two bright ones.

My
understanding (from Trey) is that the F is slightly less efficient
("less hot") than the older M, at least I think he wrote that when he
and Steve Phillips were installing an AK4 in Steve's Khorns. As always,
I believe adjustments were made in the crossover networks (or as
Klipsch insisted, "balancing networks") to balance whatever tweeter was
being used with the other speakers in the system. I think Steve later
told me on the phone that the F was about 1 dB less efficient. That was
then. If the Fs were slightly improved a bit later (as we hear), then
they may be equal to the M in efficiency now.

I always wonder
about where the screech comes from when a fairly good tweeter is accused
of being screechy. Not only have the K77M, and K77F flat magnets been
accused of being screechy (and the K77 and T35 rounds by some writers)
but the old JBL 075 "orange juice squeezer" super tweeter and the one
with the slot that followed it in the JBL pro line were described that
way as well. In my experience, with bad recordings, all of these can
screech (as maybe they should), but they sound fine -- and detail
revealing -- with good recordings. I know, circular -- right? But none of
the 15 ips recordings I made, and none of the dupe tapes I took home
from S.F. State University screeched with these tweeters. I had crown
reel to reel, and tended to use U47 mics. S.F. State used Ampex decks
with a bevy of mics, inc U47s, and even the venerable RCA 77 ribbons.
The San Francisco Experience used 075 tweeters, and our SFSU pub used T35s --
nary a screech.

One recordist offered the opinion that people may
err on the side of screech inducing too-close micing -- especially of
strings -- if the speakers used in the booth are anything but horns,
citing British recordings monitored on B&W speakers as one source of
the problem.

[OO1]

this thread sounds a bit like shakespeare - to be or not to be -that is the question -