Refurbishing the KEF 104/2 - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 28 Old 05-20-2019, 08:33 PM - Thread Starter
 
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Refurbishing the KEF 104/2

I acquired a set of KEF 104/2 as part of a garage sale bundle. Using it to test equipment in my garage, I realize how well these things sound. Intrigued, I embarked on restoring them.

Here is a review I found - http://www.audioreview.com/product/s...kef/104-2.html Theyre well reviewed online despite their age.

Here is what they looked like when they arrived.



It has some wear marks, no dings.



What I intend to do is to recover the grilles with new cloth, recone the center suspension on 4 woofers, color the wear marks black, sand lightly, and refinish with black Minwax polystain.

Here is a pic of the insides.



A huge crossover.



A prepped woofer for reconing vs a raw woofer just out of the cabinet.



Two more prepped woofers.



I am not sure if there is any benefit in recapping the crossover. Ive heard that capacitors from the 1980s onwards dont dry out like ones from 1970s and earlier. I'll figure it out later.

Another thing I am considering is if I will refill the ferrofluid or simply replace the tweeter.

If there is any interest, I'll post the finish restoration here in about 2-3 weeks. I take my time with these, putting in an hour every few days.

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post #2 of 28 Old 05-20-2019, 08:43 PM
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Take a closer picture of the crossover, if those caps are electrolytic, maybe, if they are not, you don't need to recap. The speakers look really beat up, all the dust cap are peeled off!! I am not sure I would put in money on it. But those are Reference series speakers.


You do recone on speakers yourself?

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Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.

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post #3 of 28 Old 05-20-2019, 08:51 PM
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Did you already put this on ebay? I was looking around for pricing and I swear that's yourshttps://www.ebay.com/itm/264322709429?ul_noapp=true

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #4 of 28 Old 05-20-2019, 09:02 PM - Thread Starter
 
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Did you already put this on ebay? I was looking around for pricing and I swear that's yourshttps://www.ebay.com/itm/264322709429?ul_noapp=true
Yep, those are mine. I tried selling them as-is but it was a no-go. More to skip refurbishing. I do not expect them to sell tomorrow when that auction ends so I started the restoration.

I will recone them myself. Its a very easy process. Almost like a kindergarten project. I used to recoil JBL pro speakers as well as a concert tech. It's a usefull skill.

The woofers are not beat up at all. It is a well known phenomena that neoprene suspension on speakers deteriorate with age. I already knew of the issue even before I bought them. They actually sound very nice. I am reconing because I am a bit OCD.

Here is the cone donut kit off eBay - https://www.ebay.com/itm/KEF-Referen...4AAMXQCgpRu3y8

I will attempt to change the ferrofluid first. I do not mind spending 100 bucks and some change on a project like this as I do take pleasure in working with my hands.
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post #5 of 28 Old 05-20-2019, 09:40 PM
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Yep, those are mine. I tried selling them as-is but it was a no-go. More to skip refurbishing. I do not expect them to sell tomorrow when that auction ends so I started the restoration.

I will recone them myself. Its a very easy process. Almost like a kindergarten project. I used to recoil JBL pro speakers as well as a concert tech. It's a usefull skill.

The woofers are not beat up at all. It is a well known phenomena that neoprene suspension on speakers deteriorate with age. I already knew of the issue even before I bought them. They actually sound very nice. I am reconing because I am a bit OCD.

Here is the cone donut kit off eBay - https://www.ebay.com/itm/KEF-Referen...4AAMXQCgpRu3y8

I will attempt to change the ferrofluid first. I do not mind spending 100 bucks and some change on a project like this as I do take pleasure in working with my hands.
Ha ha, I might hit on your knowledge on speakers. I know nothing about speakers, only thing I know is buy and listen.


I am kind of nervous, just dole out $3600 for a used pair of speakers. Don't know whether I did the right thing.

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #6 of 28 Old 05-20-2019, 09:47 PM - Thread Starter
 
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Ha ha, I might hit on your knowledge on speakers. I know nothing about speakers, only thing I know is buy and listen.


I am kind of nervous, just dole out $3600 for a used pair of speakers. Don't know whether I did the right thing.
Audition, audition, audition. As long as they function correctly, you won't know the sound of it until it actually comes into your home.

Good luck!
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post #7 of 28 Old 05-20-2019, 10:00 PM
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Where do you live in LA? I am planning to pick up the speakers next weekend ( 6/1 or 6/2) in Ocean Side as seller prefers weekend. I have to check with my big boss whether she's willing to spend time listening to hifi as she's not into this. But I am definitely interested in listening to your speakers and amps. What is your schedule like?


Big boss kind of wanting to make it a get away. We used to always go to Monterrey Park and Richman to eat and visit her cousin. But we have not been down there since the cousin died 2 years ago.

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #8 of 28 Old 05-20-2019, 10:14 PM - Thread Starter
 
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Where do you live in LA? I am planning to pick up the speakers next weekend ( 6/1 or 6/2) in Ocean Side as seller prefers weekend. I have to check with my big boss whether she's willing to spend time listening to hifi as she's not into this. But I am definitely interested in listening to your speakers and amps. What is your schedule like?


Big boss kind of wanting to make it a get away. We used to always go to Monterrey Park and Richman to eat and visit her cousin. But we have not been down there since the cousin died 2 years ago.
I'm at Venice Beach. PM me your schedule to be here, I will check and let you know. If it works, I'll serve some refreshments to cover the big boss while we listen a little. Let me know, maybe it can be arranged.
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I'm at Venice Beach. PM me your schedule to be here, I will check and let you know. If it works, I'll serve some refreshments to cover the big boss while we listen a little. Let me know, maybe it can be arranged.

Ah, I looked up the location, looks like it's about 15 to 20miles from Monterrey Park. Just HW10 all the way.


I'll talk to big boss and try to convince her and I'll PM you. If you don't mind, I would like to bring one of my amp over and let you listen to it and see what you think. I won't put too much hope because your taste is MOSFET and tubes, my amp is pure bi-polar transistors, design similar to Adcom GFA565, Krell topology in general......More Adcom 565 as I think it's much superior circuit design even though the topology is similar. It's more neutral, clear, transparent type, not the warmer type. I can even bring my home made speaker cables to see whether you can tell the difference.

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #10 of 28 Old 05-20-2019, 11:10 PM - Thread Starter
 
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Ah, I looked up the location, looks like it's about 15 to 20miles from Monterrey Park. Just HW10 all the way.


I'll talk to big boss and try to convince her and I'll PM you. If you don't mind, I would like to bring one of my amp over and let you listen to it and see what you think. I won't put too much hope because your taste is MOSFET and tubes, my amp is pure bi-polar transistors, design similar to Adcom GFA565, Krell topology in general......More Adcom 565 as I think it's much superior circuit design even though the topology is similar. It's more neutral, clear, transparent type, not the warmer type. I can even bring my home made speaker cables to see whether you can tell the difference.
That would be cool. The start of June is good for me too as my house guests will be gone by then.

Will PM my phone number.
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post #11 of 28 Old 05-21-2019, 01:28 AM
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I sold the 104/2. Not as nice as the 105 or 107 but not bad with KEF's custom KUBE made for them inserted between the preamp and power amp (or in a tape monitor loop).

Those boxes are probably hard to come by at this point though.
---

KEF was one of the very first companies to introduce several innovations which are almost universal these days:

- plastic cones, originally Bextrene, for the woofers instead of the standard material, paper pulp
- CAD design and analyzer systems
- driver surface laser scans to determine non-pistonic break up modes (distortion) at high output levels

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post #12 of 28 Old 05-21-2019, 03:55 PM
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That would be cool. The start of June is good for me too as my house guests will be gone by then.

Will PM my phone number.

Sorry, I change my mind on the JM Lab Diva Utopia, I cancelled the purchase. It's just too far away and a lot of money taking a big chance that I never heard the speakers before. So I am not coming down. But if I even visit Monterrey Park, I'll visit you.


Big boss also rather spend more money to get a new pair. I have to think about that, it's a lot of money. I am just too cheap.
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Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #13 of 28 Old 05-21-2019, 04:01 PM - Thread Starter
 
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Sorry, I change my mind on the JM Lab Diva Utopia, I cancelled the purchase. It's just too far away and a lot of money taking a big chance that I never heard the speakers before. So I am not coming down. But if I even visit Monterrey Park, I'll visit you.


Big boss also rather spend more money to get a new pair. I have to think about that, it's a lot of money. I am just too cheap.
If you have a high power high current amp, get a Maggie Even the used ones are awesome.

My next speaker purchase will be a Klipsch Forte III
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If you have a high power high current amp, get a Maggie Even the used ones are awesome.

My next speaker purchase will be a Klipsch Forte III

My amps are high current, but not high power. It will drive a 2ohm speakers a lot better than low efficiency speakers like Maggie. The Maggie my friend has is 6ohm, that make my amps only 75W. I need 4ohm or even 2ohm speakers to make my amp 100W or 200W respectively.


Now I don't know what to get, I wish the Divas are closer and I have a chance to listen to it first. I hate shopping for new speakers, don't even know where to start.


You have tube amps, Klipsch should work really well.


Back to your Kef, do you have to recone the speakers? How do you align the cone so it doesn't stick? Seems very hard to me, that's the reason I never get into monkeying with speakers.

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #15 of 28 Old 05-21-2019, 06:27 PM - Thread Starter
 
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Tweeter surgery done. Success.





Going to refill with ferrofluid and then put them back together.

Next stop, da woofers.
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What did you do? You replace the cone and voice coil of the tweeters? You buy parts on ebay? How do you align the voice coil in the gap? This is interesting.


Speakers always inriquing to me. I used different guitar speakers, the same brand, looked the same, they sounded totally different. I am not talking about speakers with crossover, just a simple 12" guitar speaker from same Warehouse speaker brand, I can get the British voicing(British Invasion) and America voicing(Veteran).

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.

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What did you do? You replace the cone and voice coil of the tweeters? You buy parts on ebay? How do you align the voice coil in the gap? This is interesting.


Speakers always inriquing me. I used different guitar speakers, the same brand, looked the same, they sounded totally different. I am not talking about speakers with crossover, just a simple 12" guitar speaker from same Wearhouse brand, I can get the British voicing and America voicing.
I took the tweeter apart to refill with ferrofluid. After 30 years, it has already dried out. The ferrofluid supposed to reduce distortion at high power and acts as some sort of lubricant. Its not a user serviceable procedure, but its easy enough.

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Interesting, is that you?


Do you know whether the tweeters in my JM Lab have ferrofluid? How do you know whether you need to change it?

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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Are you saying that speakers age? That they need routine maintenance like everything else? That even if one is careful, not over driving the speaker, it still need to change ferrofluid and maintain them?


If so, it's just as well I changed my mind of buying the Divas. I thought if they are good, they are trouble free forever.

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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Ferrofluid dissipates heat from the voicecoil so it does not melt/deform quickly, supposedly increasing power handling capability.

At least some Focal drivers use it. Example: http://site.diy-loudspeakers.com/ima...AUDIOM_TLR.pdf

In A/V reproduction accuracy, there IS no concept of "accounting for personal taste/preference". As art consumers we don't "pick" the level of bass, nor the tint/brightness of a scene's sky, any more than we pick the ending of a novel or Mona Lisa's type of smile. "High fidelity" means "high truthfulness", faithful to the original artist's intent: an unmodified, neutral, accurate copy of the original master, ideally being exact and with no discernable alterations, aka "transparency".

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post #21 of 28 Old 05-21-2019, 10:10 PM - Thread Starter
 
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Are you saying that speakers age? That they need routine maintenance like everything else? That even if one is careful, not over driving the speaker, it still need to change ferrofluid and maintain them?


If so, it's just as well I changed my mind of buying the Divas. I thought if they are good, they are trouble free forever.
It really depends on the design and the condition the speakers are exposed to.

Tweeter designs with ferrofluid need to be replaced or refilled because the fluid dries out. The highs will not sound as sweet even if they are barely used. I'd say 20 years and over is around when I would start to doubt their condition.

The KEFs I am rebuilding sounded perfectly fine. But the fluid was dried out. If I were to power them up and play them for a long time, there is a possibility they may burn out. The fluid allows heat to dissipate into the chassis, besides other benefits. Without the fluid, the voice coil has no contact to the rest of the tweeter.

For woofers, neoprene surrounds degrade rather fast. 5 years, sometimes even less. This almost doesnt happen for cloth surrounds. Butyl rubber surrounds are pretty hardy too.

As for cross overs, if the caps look good and are late 80's or later, I won't replace them unless I can hear something wrong. For 70's and earlier, all of them come off.

Some MDF cabinets also do not survive aging well. Ive seen MDF turn into crumbly crap.

When buying used speakers that are 20 years old and over, I look into serviceability and parts availability. If other people are rebuilding them, thats a good sign.
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My amps are high current, but not high power. It will drive a 2ohm speakers a lot better than low efficiency speakers like Maggie. The Maggie my friend has is 6ohm, that make my amps only 75W. I need 4ohm or even 2ohm speakers to make my amp 100W or 200W respectively.


Now I don't know what to get, I wish the Divas are closer and I have a chance to listen to it first. I hate shopping for new speakers, don't even know where to start.


You have tube amps, Klipsch should work really well.


Back to your Kef, do you have to recone the speakers? How do you align the cone so it doesn't stick? Seems very hard to me, that's the reason I never get into monkeying with speakers.
You've got to try high efficiency speakers. That and horns.
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post #23 of 28 Old 05-21-2019, 11:23 PM
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It really depends on the design and the condition the speakers are exposed to.

Tweeter designs with ferrofluid need to be replaced or refilled because the fluid dries out. The highs will not sound as sweet even if they are barely used. I'd say 20 years and over is around when I would start to doubt their condition.

The KEFs I am rebuilding sounded perfectly fine. But the fluid was dried out. If I were to power them up and play them for a long time, there is a possibility they may burn out. The fluid allows heat to dissipate into the chassis, besides other benefits. Without the fluid, the voice coil has no contact to the rest of the tweeter.

For woofers, neoprene surrounds degrade rather fast. 5 years, sometimes even less. This almost doesnt happen for cloth surrounds. Butyl rubber surrounds are pretty hardy too.

As for cross overs, if the caps look good and are late 80's or later, I won't replace them unless I can hear something wrong. For 70's and earlier, all of them come off.

Some MDF cabinets also do not survive aging well. Ive seen MDF turn into crumbly crap.

When buying used speakers that are 20 years old and over, I look into serviceability and parts availability. If other people are rebuilding them, thats a good sign.
Thanks


Just as well I backed out of the deal then. Big boss willing to let me get more expensive new speakers now, she too worry about the age of the speakers. Luckily I saw your pictures and start questioning this. Are all tweeters ferrofluid?


Now my problem is I don't even know where to start looking. I am not excited in going all over the place to listen, that's the reason I played it safe and wanted to get the Divas as I have JM Lab already. There are not that many hifi stores in the bay area.....surprise surprise. How are people try out speakers.....matter of fact amps and other components? There were a lot of stores in the 90s when I was actively shopping.


If it's not because of I need better speakers to test out my amps, I honestly am very happy with my Spectral 913.1 and willing to live with it for good.


BTW, my Spectral 913.1 is in tip top condition, never have extreme temperature, the cone and the surrounding looks perfect. Only thing I don't know is whether the tweeter has ferrofluid. I think this is the tweeter in my speakers, not 100%, but very close.
https://www.ebay.com/itm/2-FOCAL-TSC...ry!94087!US!-1


Can you tell?

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #24 of 28 Old 05-22-2019, 05:13 AM - Thread Starter
 
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It appears to not have ferro fluid based on these specs - http://www.gammaelectronics.xyz/audi...995_jmlab.html

The foam surrounds of the tweeter can degrade and a repair tutorial is available here - https://m.youtube.com/watch?v=M9Kb7QyV8zY

Parts appear to be available.

Note, the repair involves handling the voice coil wire. That is a delicate process.
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post #25 of 28 Old 05-22-2019, 09:29 AM
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Wow, I didn't even find the description of my speakers like you found!!! Thanks.


The youtube video is not my tweeters, but the idea is the same as described in the article that the voice coil is smaller than the dome. The article did not say it has ferrofluid also. That make me feel better. The foam and everything still look like brand new on my speakers. It's been in the living room all these years and never subjected to extreme temperature. Everything is still in really good condition. I won't worry about the condition of the speakers as long as there is no ferrofluid.


To be honest, I am actually not very excited in buying a new pair of speakers, I am happy with what I have. The only reason is as I improved my amps, I just feel the speakers become the bottle neck and I fear the speakers limit how much I can judge my amps. Maybe I falling into thinking my speakers sound the best and cannot imagine any speaker will sound better.......like when I had the Kef and cannot imagine there's anything better........until I took the chance to buy the JM Lab!!!. Sadly, I think this is more common and that's why a lot of people think high end speakers are snake oil.


Thanks

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #26 of 28 Old 05-22-2019, 09:54 AM - Thread Starter
 
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Originally Posted by alan0354 View Post
Wow, I didn't even find the description of my speakers like you found!!! Thanks.


The youtube video is not my tweeters, but the idea is the same as described in the article that the voice coil is smaller than the dome. The article did not say it has ferrofluid also. That make me feel better. The foam and everything still look like brand new on my speakers. It's been in the living room all these years and never subjected to extreme temperature. Everything is still in really good condition. I won't worry about the condition of the speakers as long as there is no ferrofluid.


To be honest, I am actually not very excited in buying a new pair of speakers, I am happy with what I have. The only reason is as I improved my amps, I just feel the speakers become the bottle neck and I fear the speakers limit how much I can judge my amps. Maybe I falling into thinking my speakers sound the best and cannot imagine any speaker will sound better.......like when I had the Kef and cannot imagine there's anything better........until I took the chance to buy the JM Lab!!!. Sadly, I think this is more common and that's why a lot of people think high end speakers are snake oil.


Thanks
If you are indeed buying, some designs that excite me are full range, horn loaded and very high efficiency. Zu's, Klipsch's and the like.
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post #27 of 28 Old 05-22-2019, 12:49 PM
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If you are indeed buying, some designs that excite me are full range, horn loaded and very high efficiency. Zu's, Klipsch's and the like.

I personally don't like horn speakers, I like dome tweeters.


BTW, was that you in the youtube you linked on the cleaning of the ferrofluid?

Own designed power amp, own designed preamp, JM LAB Spectral 913.1 speakers, Rythmik F12SE sub.
Not hooked up: Nakamichi Stasis PA-7 power amp, Velodyne VA1210 sub, Kef Reference Series center, Kef Bookshelf speaker, Monitor Audio bookshelf speaker, Infinity rear speakers. Acurus 3X200W amp.
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post #28 of 28 Old 05-22-2019, 03:13 PM - Thread Starter
 
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I personally don't like horn speakers, I like dome tweeters.


BTW, was that you in the youtube you linked on the cleaning of the ferrofluid?
nope. not me.
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