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K-77 impedance mismatch


gigantic
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I just got a deal on a pair of K-77s that I hope to use on the Super Heresy/Baby Cornwallis that I plan to build, however, there’s a reason that I got them for a bargain price: IIRC, one of the tweeters reads 6.5 ohms, which seems normal, however the other reads somewhere around 11-11.5 ohms. Short of replacing the driver, is there an easy fix for this? Would a replacement diaphragm solve the problem? I also have a square magnet K-77 that I can use, but I’d rather keep it matchy-matchy. What is the recommended replacement driver? As far as I can tell, B&C drivers seem to be out of stock everywhere. 
 

tia,

 

Lance

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the tweeters you purchased are   Alnico  rounds magnets EV T 35 's composed of an 8 Ohms tweeter   , and a 16 Ohms tweeter , both DO NOT share the same diaphragm or magnet , but they use the same tweeter lens  , so you can  use a square magnet k77 with a new diaphragm ,  and you might not even hear a difference 

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Are there any good replacement diaphragms available or only the cheap, bad ones from China? Didn't the last good diaphragms come from the Philippines?

 

https://audioxpress.com/article/remembering-the-electro-voice-t35-super-tweeter

 

I had my Alnico K77 checked last year. They were remagnetised. I had bought replacement diaphragms in good faith, thinking that after 45 years, new ones might be better. With my brand new original Atlas K55 diaphragms this was exactly the case, clearly audible. 
But my workshop said after checking, electrically and acoustically, that my new K77/T35 diaphragms were inferior to the old original ones, they were the Chinese diaphragms although the Dutch dealer assured me they were better. Of course the original ones remained.

 

I had bought these diaphragms from the dealer in the link but had not used them after analysis by my competent repair shop.

 

https://speakerrepairshop.nl/en/diaphragms/for-klipsch/diaphragm-for-klipsch-k-77-tweeter/a-3364-10000063

 

 

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49 minutes ago, gigantic said:

I just got a deal on a pair of K-77s that I hope to use on the Super Heresy/Baby Cornwallis that I plan to build, however, there’s a reason that I got them for a bargain price: IIRC, one of the tweeters reads 6.5 ohms, which seems normal, however the other reads somewhere around 11-11.5 ohms. Short of replacing the driver, is there an easy fix for this? Would a replacement diaphragm solve the problem? I also have a square magnet K-77 that I can use, but I’d rather keep it matchy-matchy. What is the recommended replacement driver? As far as I can tell, B&C drivers seem to be out of stock everywhere. 
 

tia,

 

Lance

Who cares about a magnet no one will ever see? As long as they curve the same. Unless of course you want to maximize their resale value by having everything matched as original as possible to get the most money, then go off and built Supers.

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On 9/10/2022 at 4:33 PM, OO1 said:

the tweeters you purchased are   Alnico  rounds magnets EV T 35 's composed of an 8 Ohms tweeter   , and a 16 Ohms tweeter , both DO NOT share the same diaphragm or magnet , but they use the same tweeter lens  , so you can  use a square magnet k77 with a new diaphragm ,  and you might not even hear a difference 

I can hear the difference between Alnico and M very well. I have both pairs and prefer the Alnico version definitely.

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10 minutes ago, OO1 said:

 That’s odd, I couldn’t find them on either website when I tried looking yesterday. At any rate, if I were to replace the drivers, I’d rather get @Dave A sMAHL’s, but before I do that, I’d like to build the cabinets and make sure I’ve got everything dialed before making that investment. 

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26 minutes ago, ClaudeJ1 said:

Who cares about a magnet no one will ever see? As long as they curve the same. Unless of course you want to maximize their resale value by having everything matched as original as possible to get the most money, then go off and built Supers.

I don’t care so much about resale value as much as a maxim that a mentor told me years ago: “how you do anything, is how you do everything.” 
 

the upshot is that I got the 8 & 16 ohm tweeters for the price of one, so I might be able to sell one and recoup the cost. So for the time being, I’ll use the K-77M and live with the shame that only I know… 😉 actually, you all know now, too. 😳

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25 minutes ago, ClaudeJ1 said:

Oh, really? Why is that? You prefer an early HF rolloff from 7.5 Khz. on down from tired, 60 year old magnets to a fresher ceramic one that hangs in there until 12 Khz.? Emotional testing is alive and well I see.

I had the K77 Alnico remagnetised last year at this workshop, link below. Like here at minute 5:50 with another driver on the same machine. Tested result, +1.5 dB SPL and up to 16 KHz.

 

https://youtu.be/7TOlbvnv1RY

 

Sometimes no emotions help.

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3 hours ago, KT88 said:

I had the K77 Alnico remagnetised last year at this workshop, link below. Like here at minute 5:50 with another driver on the same machine. Tested result, +1.5 dB SPL and up to 16 KHz.

 

https://youtu.be/7TOlbvnv1RY

 

Sometimes no emotions help.

Agreed. As long as your process step tried to make and apple to apples comparison. However not publishing the curves here will not have an effect of changing minds unless your fully remove the influence of emotion from your Opinion, which remains as perceived emotional testing in it's incomplete presentation. I emotionally and technically prefer NeoDymium myself and I have curves to prove it.

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Unfortunately I don't have any graphs about the remagnetisation of the K77 so I have to rely on what I was told and what I hear now. NeoDymium is a double-edged sword for me. From my point of view, it presents a certain acoustic coldness, albeit very clear and distortion-free. I would have been very curious if, instead of the TAD 4002 NeoDymium, we had done all the measurements for the K402 UJ with a TAD 4001 Alnico back then...even if the 4001 is a bit more expensive.

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13 hours ago, KT88 said:

Unfortunately I don't have any graphs about the remagnetisation of the K77 so I have to rely on what I was told and what I hear now. NeoDymium is a double-edged sword for me. From my point of view, it presents a certain acoustic coldness, albeit very clear and distortion-free. I would have been very curious if, instead of the TAD 4002 NeoDymium, we had done all the measurements for the K402 UJ with a TAD 4001 Alnico back then...even if the 4001 is a bit more expensive.

I think the bigger factor by far is diaphragm material.

 

22 hours ago, jimjimbo said:

@Dave A  Out of stock?

I just got 100 DE-120's in and asked about ordering DE-10's. I took the 40 some in stock and was told they had no idea when a new order for DE-10's could be filled. I ordered the DE-120's back in January and took delivery six months later. Supply for me so far has been uninterrupted only because I have been willing to tie up lots of $ to keep them on hand. I am worried enough to consider trying a Beyma driver sent to me from a customer to see how it fares.  I think things are going to get really bad in the near future and out of stock will be an even more common refrain. Guy in Denmark I talked to recently has been waiting 8 months for resistors.

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On 9/10/2022 at 10:33 AM, OO1 said:

the tweeters you purchased are   Alnico  rounds magnets EV T 35 's composed of an 8 Ohms tweeter   , and a 16 Ohms tweeter , both DO NOT share the same diaphragm or magnet , but they use the same tweeter lens  , so you can  use a square magnet k77 with a new diaphragm ,  and you might not even hear a difference 

They arrived in the mail today. Here’s the weird thing: they have sequential serial numbers and Klipsch labels.  I’ll pull out my multimeter later and get a reading on them, perhaps the seller got the reading in error. 

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