Jump to content

The historical sequence of K55 and K77 versions and their genuine combinations.


KT88

Recommended Posts

I have a 1977 Lascala with original K55 V single phase plug and round alnico K77.

I am very happy with it and my question is partly out of curiosity, partly to maybe experiment a bit. But I will be able to restore and preserve the original condition. I have a lot of respect for originality, which I really like sonically as well.

My question, or it is also a hypothesis. It is often the case that one measure leads to another measure even if someone would not have thought at the beginning that it might become necessary.

That's why historically I wonder if the development of K55 versions happened independently of the development of K77 versions, or if there were interdependencies.

Specifically: In about 1979 or around that? the square magnet K77 M appeared. But not because it was progress but because Alnico became too expensive. Only one year later, the dual phase plug appeared in the K55V.

Could it be that the interaction with the K77 M caused PWK to make a change to the K55V? Is it possible that the single phase plug simply harmonises very well with the alnico K77?

Two things,a) in the whole period between 1977 and 1983 or so? no change was made to the AA Xover, b) in real production the dual phase plug K55V never played together with the alnico K77.

It is always very easy to say that a thing is better or worse when you look at it or measure it in isolation, like the sheet of a dual phase plug K55 V. But the interaction of all the components is the great art, you surely know what I mean.

So, could playing a K55V dual phase plug together with an alnico K77 be disappointing? Perhaps PWK's intention in developing the dual phase plug K55 V was simply to connect more seamlessly with the slightly louder K77M? and not primarily because of the 9 Khz peak issue (which is not really audible for most people according to information here in the forum)? But the gain was so small that PWK returned to the single phase plug after only one year for the sake of a sensible investment with good reason and equally good sound? 

I look forward to answers, also very much if some have had experience with this.

Link to comment
Share on other sites

 both versions of the K55V  --the K55M- the K77  -round and square  are compatible with each other -whether AA or AL - ( not sure about the A or AL-3)

 

ATLAS  reverted production to the single phase plug  k55x  /PD5VH  in the early 80's - ATLAS did retain 1 feature of the Dual phase plug k55V , the top plate with soldered lugs versus the push pin top plate -

Link to comment
Share on other sites

2 hours ago, KT88 said:

I have a 1977 Lascala with original K55 V single phase plug and round alnico K77.

I am very happy with it and my question is partly out of curiosity, partly to maybe experiment a bit. But I will be able to restore and preserve the original condition. I have a lot of respect for originality, which I really like sonically as well.

My question, or it is also a hypothesis. It is often the case that one measure leads to another measure even if someone would not have thought at the beginning that it might become necessary.

That's why historically I wonder if the development of K55 versions happened independently of the development of K77 versions, or if there were interdependencies.

Specifically: In about 1979 or around that? the square magnet K77 M appeared. But not because it was progress but because Alnico became too expensive. Only one year later, the dual phase plug appeared in the K55V.

Could it be that the interaction with the K77 M caused PWK to make a change to the K55V? Is it possible that the single phase plug simply harmonises very well with the alnico K77?

Two things,a) in the whole period between 1977 and 1983 or so? no change was made to the AA Xover, b) in real production the dual phase plug K55V never played together with the alnico K77.

It is always very easy to say that a thing is better or worse when you look at it or measure it in isolation, like the sheet of a dual phase plug K55 V. But the interaction of all the components is the great art, you surely know what I mean.

So, could playing a K55V dual phase plug together with an alnico K77 be disappointing? Perhaps PWK's intention in developing the dual phase plug K55 V was simply to connect more seamlessly with the slightly louder K77M? and not primarily because of the 9 Khz peak issue (which is not really audible for most people according to information here in the forum)? But the gain was so small that PWK returned to the single phase plug after only one year for the sake of a sensible investment with good reason and equally good sound? 

I look forward to answers, also very much if some have had experience with this.

This looks interesting but I can't read this.  I am an old curmudgeon I guess.

 

Next to the " key there is one named "enter"

  • Haha 1
Link to comment
Share on other sites

Here is the information I have gathered through the years regarding the K55V - K77Alnico - K77M.

 

I own 1978 Klipschorns which came factory built with the K33E woofer, push-pin connector single phase plug K55V midrange driver and the Alnico round back K77 tweeter.  Currently I am using the dual phase plug modified K55V and the K77M tweeter.  Crossover network remains AA.  Essentially my Klipschorns are updated to second quarter 1980 models in this configuration; the dual phase plug being implemented on home entertainment speakers built on or after after March 24, 1980.

 

The change over from K77 alnico to K77M ceramic magnet was around the same time as the K55V dual phase plug midrange driver was introduced.  I think it would be possible for some speakers made in early 1980 to have had the K77M tweeter with the push pin connector K55V.  Inventory on hand of the alnico K77 would have determined that.

 

I spoke with Jim Hunter a few years back and we discussed the two tweeter versions at length.  Seems one of the first jobs at Klipsch for Jim was testing the new K77M tweeters against the K77 alnico to make sure the new model was compatible.  According to Jim, both tweeters had the same sensitivity so no change to crossover networks were necessary.  Keep in mind in those days all of the Klipsch models used the same midrange drivers and tweeters so a change to either one would mean modifying the crossover networks across the board!  

 

The K55V dual phase plug was the design of Klipsch engineer Gary Gillum.  The idea was to improve response in the 4 - 6K region of the K55V driver.  Gary's design worked and Atlas, the manufacturer of the K55, agreed to build the special version for Klipsch.  Shortly after the modified K55V went into use it became apparent that the glue used to secure the phase plug could let go causing the plug to dislodge; probably more so in the industrial series than the home series speakers.  Obviously not all of the drivers had this problem but enough did so I imagine some serious discussions between Klipsch and Atlas took place.  A solution to the problem never materialized and Atlas ceased production of the modified version.  This led to the Electrovoice K55M which had a different sensitivity than the Atlas K55 which led to the crossover network changes in 1983.

 

Concerning the softer playing K77 alnico tweeters, I spoke with Trey Canon regarding this issue years ago as the K77s in my Klipschorns were exhibiting this problem.  Trey explained that the alnico tweeters can loose magnetism over the years which will cause the tweeter to play softer.  I agree with Trey as I have come across many K77s that play soft.  The K77M version does not seem to have this problem, at least not yet! 

 

Which combination is best?  Because of the magnet issue on the K77, I prefer the K77M.  There is an audible difference between the K55V push-pin connector unit and the dual phase plug modified K55V.  To my ears the modified version has a smoother sound.  Others may not hear a difference or disagree!

 

For historical correctness, only Klipsch could possibly answer the question of which tweeter / midrange combination were used, especially in early 1980.  Since both tweeter versions are compatible, either may be used with the standard or modified K55V and work properly.         

Edited by JEM
change wording - would to could
  • Like 2
  • Thanks 2
Link to comment
Share on other sites

Jim, thank you very much for the very detailed and valuable information.
I have a reason why I would not trade my K77 for K77M...or maybe I would, to keep the balance of the SPL? I would maybe buy them in addition as an alternative solution. It is a pity if the alnico K77 should have become more powerless. But I love the sound of alnico magnets, may be I could try first new diaphragms. Momently I am happy with the SPL of my tweeters even if they are on the „soft“ side. It's about the magic moment when the sound emerges from silence. For example, very quiet string instruments that just breathe. In my opinion, alnicos are much finer and more transparent than ferrite or ceramic magnets.

I also have a question regarding the new Atlas PD-5VH alnico in this circumstances, are they identically good as the old K55V single phase plugs and interchangeable without any acoustic difference? Just in case I need new drivers.

Link to comment
Share on other sites

Not all K-77 or K55V Alnico demagnatize  ,and even if they do , they can get re-magnetized quite easily -

 

the older  Atlas K55V   and the PD5VH have identical specs  except for one difference ---the older  K55V has push pin terminals on the top plate assembly   while the /K55X /PD5VH has a  top plate with  solder lugs  -cool thing about the push pin terminals is that you can replace the driver without unsoldering/soldering --

 

https://community.klipsch.com/uploads/monthly_10_2013/post-22082-13819799614012.png

Link to comment
Share on other sites

The new PD5VH in my opinion is close to the single phase plug K55V.  I would have to ask Roy if any tests have been done comparing the old K55V to the new PD5VH in the lab concerning frequency response and sensitivity before I can say if they are an exact replacement.        

Link to comment
Share on other sites

1 hour ago, JEM said:

This led to the Electrovoice K55M which had a different sensitivity than the Atlas K55 which led to the crossover network changes in 1983.

 

 

 

Do you know the difference in sensitivity? 

 

I am guessing 1 db as the AL used a -4db transformer vs -3 in the Type A/  AA. (I might be wrong)

Link to comment
Share on other sites

36 minutes ago, RandyH000 said:

Not all K-77 or K55V Alnico demagnatize  ,and even if they do , they can get re-magnetized quite easily -

 

the older  Atlas K55V   and the PD5VH have identical specs  except for one difference ---the older  K55V has push pin terminals on the top plate assembly   while the /K55X /PD5VH has a  top plate with  solder lugs  -cool thing about the push pin terminals is that you can replace the driver without unsoldering/soldering --

 

https://community.klipsch.com/uploads/monthly_10_2013/post-22082-13819799614012.png

I could be wrong (it happens) but the PD-5VH rolls off steeply long before the 6000 hz crossover point in the A or AA. Did the original 55V do that as well.

 

 

Link to comment
Share on other sites

5 minutes ago, MookieStl said:

I could be wrong (it happens) but the PD-5VH rolls off steeply long before the 6000 hz crossover point in the A or AA. Did the original 55V do that as well.

 

 

Bobby @BEC   God Rest his Soul , had made an extensive testing of the K55X and K55V ,

 

Link to comment
Share on other sites

When I compare the frequency response and the specifications of the new PD-5VH with the curves that can be found here on the forum for the K55V (regardless of whether single or dual phase plug), then I would be afraid that the PD-5VH is not so well suited for my AA crossover. But maybe Atlas measured the new driver with a different method than ALK or BEC did with the K55V? Or the new heat resistant alnico material has less magnetic strength, or are they using different, perhaps more massive diaphragms that drop out at 4,500 Hz?

One more point that interests me a lot, I had started another thread that has no replies yet. Without hijacking this thread...regardless of the specification of the PD-5VH, is it mechanically possible to mount the old dual phase plug of the soldered K55V (of course the whole part with the thread for the horn) on a PD-5VH?

Link to comment
Share on other sites

14 hours ago, RandyH000 said:

Bobby @BEC   God Rest his Soul , had made an extensive testing of the K55X and K55V ,

 

That is a great thread. Back when people actually talked about speakers on this forum. Hmmm

Michael Colter asked the exact question that I had in my head, should you not use a 55M with an AA. I have two pair of LS both with AA. One has a 55M the other the Atlas PH-5VH. Bob doubts we can hear it and I believe him. Still curious. I have a A4500 that I might try in my LS just for kicks if I get real bored one day. As suggested, doubt I'll hear a difference, I rarely do.

Link to comment
Share on other sites

22 minutes ago, MookieStl said:

That is a great thread.

 

 the thread was made in 2006 , the drivers /diaphragms tested  were 25 years old whereas most  K55V are now 15 years older , so more wear and tear    -

comparing a brand new PD5VH or A55G in 2021  with a K55V cannot be accurate given the difference in the age of the components -

Comparative testing  of a k-55V vs a K55X should be done with a brand new diaphragm in the k55V  , and a 3rd test can be done using a k55V with a 40 year old diaphragm  -

Link to comment
Share on other sites

3 hours ago, RandyH000 said:

 the thread was made in 2006 , the drivers /diaphragms tested  were 25 years old whereas most  K55V are now 15 years older , so more wear and tear    -

comparing a brand new PD5VH or A55G in 2021  with a K55V cannot be accurate given the difference in the age of the components -

Comparative testing  of a k-55V vs a K55X should be done with a brand new diaphragm in the k55V  , and a 3rd test can be done using a k55V with a 40 year old diaphragm  -

 

Please report your results.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...