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KEF Q60 BOOKSHELF SPEAKERS - TWEETERS DIAGNOSTICS

 
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flumoxed
Junior Contributor 10+


Joined: 30 Mar 2015
Posts: 18

PostPosted: Sat Jun 27, 2015 10:38 am    Post subject: KEF Q60 BOOKSHELF SPEAKERS - TWEETERS DIAGNOSTICS Reply with quote

Hi to the Experts.

I wonder if my SP1276 tweeters are faulty as follows:

1. Removed gold-plated strap between HF and LF speaker terminals
2. Connected speaker cables to LF terminals.
3. Played HFN&RR Test CD III. No problems.
4. Relocated speaker cables to HF terminals.
5. Played HFN&RR Test CD III. Vocals are almost inaudible.

Kindly advise possible reasons before I shell out mega-bucks for new tweeters, such as:

1. No problem - normal.
2. Defective dividing (crossover) network.
3. Defective tweeters.

Many thanks for your time and expertise.

Flummoxed

The test tracks I used are at this URL:

http://s000.tinyupload.com/?file_id=79801889526878879563

TX.
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exkefman
Intermediate Contributor 25+


Joined: 19 Jun 2015
Posts: 25
Location: Cheshire, England

PostPosted: Thu Jul 02, 2015 11:13 pm    Post subject: Re: KEF Q60 BOOKSHELF SPEAKERS - TWEETERS DIAGNOSTICS Reply with quote

flumoxed wrote:
Hi to the Experts.

I wonder if my SP1276 tweeters are faulty as follows:

1. Removed gold-plated strap between HF and LF speaker terminals
2. Connected speaker cables to LF terminals.
3. Played HFN&RR Test CD III. No problems.
4. Relocated speaker cables to HF terminals.
5. Played HFN&RR Test CD III. Vocals are almost inaudible.


Hi there

Quote:
Kindly advise possible reasons before I shell out mega-bucks for new tweeters, such as:

1. No problem - normal.
2. Defective dividing (crossover) network.
3. Defective tweeters.

Many thanks for your time and expertise.

Flummoxed

The test tracks I used are at this URL:

http://s000.tinyupload.com/?file_id=79801889526878879563

TX.


It's not case #1 - by connecting a signal to the HF terminals on the rear of the speakers, some HF sounds should come from the speakers - (as long as the sounds you play have some content above approx 3 kHz).

Which means it could be either case #2 or case #3.

There's no way of confirming either, until the drive unit and x-over's are checked.

Personally, as a HF unit is more "delicate" than a x-over, it is probably the tweeters...HOWEVER, the speakers are 25 years old...so some or all of the reversible electrolytic capacitors in the x-over *might* need replacing.
_________________
regards
Tim

(I used to work for KEF from 1988-1995 - you can see my "profile" here: http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=1706)
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flumoxed
Junior Contributor 10+


Joined: 30 Mar 2015
Posts: 18

PostPosted: Fri Jul 03, 2015 12:56 am    Post subject: Re: KEF Q60 BOOKSHELF SPEAKERS - TWEETERS DIAGNOSTICS(2) Reply with quote

exkefman wrote:
flumoxed wrote:
Hi to the Experts.

I wonder if my SP1276 tweeters are faulty as follows:

1. Removed gold-plated strap between HF and LF speaker terminals
2. Connected speaker cables to LF terminals.
3. Played HFN&RR Test CD III. No problems.
4. Relocated speaker cables to HF terminals.
5. Played HFN&RR Test CD III. Vocals are almost inaudible.


Hi there

Quote:
Kindly advise possible reasons before I shell out mega-bucks for new tweeters, such as:

1. No problem - normal.
2. Defective dividing (crossover) network.
3. Defective tweeters.

Many thanks for your time and expertise.

Flummoxed

The test tracks I used are at this URL:

http://s000.tinyupload.com/?file_id=79801889526878879563

TX.


It's not case #1 - by connecting a signal to the HF terminals on the rear of the speakers, some HF sounds should come from the speakers - (as long as the sounds you play have some content above approx 3 kHz).

Which means it could be either case #2 or case #3.

There's no way of confirming either, until the drive unit and x-over's are checked.

Personally, as a HF unit is more "delicate" than a x-over, it is probably the tweeters...HOWEVER, the speakers are 25 years old...so some or all of the reversible electrolytic capacitors in the x-over *might* need replacing.


Hi, Tim.

Many thanks for your time and input.
The tweeters reproduce the ratchet test track OK. The walkabout vocal track is barely audible, though. Perhaps that is because the lowest frequency response of the tweeters is higher than vocal frequency. (I don't know much on the subject so that is why I came here.)

You rightly highlighted that the speakers are over 25 years old and I was thinking of changing them to another brand, because of no KEF service support in Japan. However, I am going to redo the crossovers first and then decide.

Once again, many thanks!
Flummoxed
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speakerguru
VIP Contributor 750+


Joined: 18 Nov 2005
Posts: 959
Location: Green Hut, Tovil

PostPosted: Fri Jul 03, 2015 9:09 am    Post subject: Reply with quote

Tweeters in most KEF systems only produce significant output above 3 kHz. There's not an enormous amount of program material up there; just a bit of "sparkle". Listen to some voices and percussion rather than test tracks. You'll surely know if a voice or cymbal is believable or muffled.
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