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104/2 low sound level

 
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keffan
Junior Contributor 10+


Joined: 19 Feb 2011
Posts: 10
Location: USA

PostPosted: Tue Oct 22, 2019 11:40 pm    Post subject: 104/2 low sound level Reply with quote

Hi,

I need some advice on my 104/2 low sound level issue. I have a pair of 104/2 earlier versions, which I had replaced donuts and ferrofluid a few years ago by myself. Both speakers performed very well until recently. The left speaker occasionally has a very low sound level (both high and low frequency) when compared to the right one--after playing for some time, I guess. However, it could come back to normal the next day. I have identified the problem is not caused by other components, i.d. turntable, preamp, or amplifier. Based on this symptom, I suspect there is one back contact within the left speaker wiring or failure of one or more components of the crossover circuit. I appreciate any advice from fellow KEF lovers. In fact, if my suspicions are correct, any speaker lovers could provide me advice or share their experience with me.

Thank you.
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martlet
Junior Contributor 10+


Joined: 30 Aug 2011
Posts: 11
Location: Atlanta, Georgia USA

PostPosted: Wed Oct 23, 2019 4:47 pm    Post subject: Reply with quote

No solution but have noticed the same problem with my recently purchased 104.2 gen2 bi-wire.
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Kef Ref Ownership: 101.1 (sold), 103.2, 104.2, 105.4
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audiolabtower
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Joined: 06 Jan 2009
Posts: 600

PostPosted: Wed Oct 23, 2019 4:58 pm    Post subject: Reply with quote

Swappimg the speakers confirms it is the specific speaker and no other component. The 104.2s have conjugate load matching components which make the crossover look complicated, the extra components provide the amp with a constant pretty resistive 4 ohm load, so very easy for the amp. Unfortunately it means a lot of reversible electrolytics, and one of these going low impedance to ground would reduce the sound, or maybe a series one going high impedance. Speakerguru might know the most common failure modes. A capacitance meter might be the way to go, unsolder one end of each cap to measure. There are some resistors in the circuit, less likely than the caps but could be measured, the inductors should be the least likely to have a problem.
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audiolabtower
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Joined: 06 Jan 2009
Posts: 600

PostPosted: Wed Oct 23, 2019 5:01 pm    Post subject: Reply with quote

If it's just the bass it could be a leak in the surrounds or doughnuts, but I would have thought the treble would be unaffected so the result would be just too bright?
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speakerguru
Über Contributor 1000+


Joined: 18 Nov 2005
Posts: 1029
Location: Green Hut, Tovil

PostPosted: Sat Oct 26, 2019 5:09 pm    Post subject: Reply with quote

audiolabtower wrote:
A capacitance meter might be the way to go, unsolder one end of each cap to measure. There are some resistors in the circuit, less likely than the caps but could be measured, the inductors should be the least likely to have a problem.


Yes. A cheap LCR meter from eBay will alllow you to check all the components.

However, if the fault is not constant it is more likely to be an intermittent connection. Check for broken wire by "wiggling" or "dry" solder joints(s) by visual inspection.
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