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KEF 104ab mod

 
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David
Intermediate Contributor 75+


Joined: 11 Jun 2003
Posts: 90
Location: Canada

PostPosted: Wed Jun 11, 2003 5:19 pm    Post subject: KEF 104ab mod Reply with quote

I just found this forum and this is my first post.

I have just purchased a set of 104abs, and was wondering if anyone has replaced the capacitors in the crossovers, or whether it is necessary. I saw another post indicating that the caps in the crossovers were closely matched and that it was unlikely to be any improvement.

Has anyone changed the internal wiring of the speakers and if so did they solder the speaker wire directly to the crossover?

Thank you.

David
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terry
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Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Wed Jun 11, 2003 11:08 pm    Post subject: Reply with quote

Pleased to have you in the Forum David.

Although I haven't got a fully functioning set of 104abs I have purchased all the drive units and other bits and pieces. I could thus make a set if I could be bothered to manufacture the cabinets. I will read any responses with interest.

I am bit sure to what extent changing the internal wiring of speakers improves the sound. I have been advised differently by different people who should know. I have Naim electronics and NACA5 cable is the preference for such amps and so it seems an obvious thing to do to incorporate NACA5 internally in the speakers. I am going to try this sometime and I will probably solder directly onto the crossovers.

I use a pair of KEFKIT3s built in 1976 but modified a bit now.
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David
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Location: Canada

PostPosted: Thu Jun 12, 2003 2:28 am    Post subject: KEF 104ab mods Reply with quote

thank you for your reply Terry. I have a Nait I and A5 cable, recently upgraded from A4.

I note in the Naim forum that A5 is very hard to work with. I saw pictures of the crossover on the KEF site and it looks delicate. I wouldn't want to fry it soldering A5 on. I have my old A4 and may use it.

Let me know how you do.

what about the capacitors. Do they age?

I saw on the LS35A site that the best set of 35As were original BBC monitors no mods.

David
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terry
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Joined: 22 Apr 2003
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Location: UK

PostPosted: Thu Jun 12, 2003 8:52 am    Post subject: Re: KEF 104ab mods Reply with quote

David wrote:
I note in the Naim forum that A5 is very hard to work with.


A hairdryer to heat the NACA5 and it bends easily.
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terry
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Joined: 22 Apr 2003
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Location: UK

PostPosted: Thu Jun 12, 2003 8:56 am    Post subject: Re: KEF 104ab mods Reply with quote

David wrote:
what about the capacitors. Do they age?


Although by initial qualification I am an electronics engineer I wouldn't like to be specific about the aging of capacitors within crossovers. They live in a relatively non-hostile environment (no heat) and so degragation may well be considerably slower. All electronic components do of course degrade with time. It would be a good test for someone to undertake - newly built crossovers vs crossovers from 70s.
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David
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Joined: 11 Jun 2003
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Location: Canada

PostPosted: Thu Jun 12, 2003 2:59 pm    Post subject: KEF 104ab mod Reply with quote

Thank you Terry. Not much current would be passing through the crossover, compared to the caps in an amplifier.

On the Naim site, I saw they recommended recapping amps after 10 years or so. My Nait is a 1986 model and I have done nothing to it. Still sounds great.

David
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terry
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Joined: 22 Apr 2003
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Location: UK

PostPosted: Thu Jun 12, 2003 11:30 pm    Post subject: Re: KEF 104ab mod Reply with quote

David wrote:
Thank you Terry. Not much current would be passing through the crossover, compared to the caps in an amplifier.

On the Naim site, I saw they recommended recapping amps after 10 years or so. My Nait is a 1986 model and I have done nothing to it. Still sounds great.

David


Yes 10 years seems to be the recommended period. I have a Hicap which is 8 years old and hasn't been recapped. My other Naim equipment (CDSII/XPS/82/250/Nait3) is well within the 10 years.
Terry
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David
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Joined: 11 Jun 2003
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Location: Canada

PostPosted: Mon Jun 30, 2003 4:31 pm    Post subject: Reply with quote

Terry I saw on the website that you rewired your Concertos using NACA5 cable, internally.

1. Did you change the wiring to the crossover and to each speaker, or just the crossover.

2. A5 is very thick, how did you solder to the crossover? and to the terminal post. I saw on the pictures that the terminals are quite fine.

3. The wires to the T27 are very thin, did you solder to these wires directly with the A5 or use any other type of connection.

Lastly, what about the result, were you able to hear a difference?


Thx

David
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terry
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PostPosted: Mon Jun 30, 2003 6:31 pm    Post subject: Reply with quote

David wrote:
Terry I saw on the website that you rewired your Concertos using NACA5 cable, internally.


David
No I haven't done so yet but I intend to do so. I now have the cable to do so when I have time.

David wrote:
Did you change the wiring to the crossover and to each speaker, or just the crossover.


I used NAC5 from amps to speakers. Internally I rewired with cable purchased from Wilmslow. As stated above I hope to replace the internal wiring from binding posts to crossovers and from crossovers to drive units with NAC5 in the near future.

David wrote:
A5 is very thick, how did you solder to the crossover? and to the terminal post. I saw on the pictures that the terminals are quite fine.

3. The wires to the T27 are very thin, did you solder to these wires directly with the A5 or use any other type of connection.


This is the challenge I have yet to meet - NACA5 is thick and inflexible. The T27s are delicate and I so will solder onto existing short 'tails' from the drive units. I will leave a short piece of finer wire onto which I will solder NACA5. That is how I have done it at the moment. My existing internal wiring is quite thick. I would use the same approach anywhere where it looked like soldering the thick wire would be difficult, problematic or likely to result in damage.

David wrote:

Lastly, what about the result, were you able to hear a difference?


I will report in due course unless someone else beats me to it. Are you thinking about it?

Terry
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David
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Joined: 11 Jun 2003
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PostPosted: Mon Jun 30, 2003 6:59 pm    Post subject: Reply with quote

Yes, but I was leery about fooling around with the soldering directly to the crossover with the A5 or A4 that I have. I modified a pair of MS Festival 2s that I had but left the short tail's on the crossover and soldered to those. Did I hear a difference. Hard to say. I have never been entirely pleased with this MS model, but got it second hand for relatively little.

If you do your tweeters, I would suggest that you use a heat sink on the tweeter side of the joint to prevent damage to the tweeter, but you are the engineer so I'm sure you would know that.

Let me know if and when your project is completed.

Best regards

David
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terry
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PostPosted: Mon Jun 30, 2003 7:02 pm    Post subject: Reply with quote

David
I have just been silly. I no longer have T27s. I replaced them with scan-speak tweeters which have more 'delicate' connections. I left short wires on them.
Terry
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