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Reccomendations for speaker repairs/serviceing
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vistisen
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Joined: 01 Sep 2006
Posts: 57
Location: Denmark

PostPosted: Tue Jan 01, 2008 4:10 pm    Post subject: Reccomendations for speaker repairs/serviceing Reply with quote

I have a pair of Reference 107s that I love listeneing to , but as some will know from these excellent forums, I am not satisfied with their upper bass. I know that they have had the drivers replaced at some point, and I think they are the wrong ones. I live in Denmark and know that I am going to have to send them to the UK to be 'looked at'. This is going to cost me serious postage Evil or Very Mad .

Where shall I send them? who knows of a company that will check them, replace drivers, (and 20 year old capacitors!) as necessary. without ripping me off. I wants these speakers to last me 20 years, I love them.
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john rasmussen
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PostPosted: Tue Jan 01, 2008 10:44 pm    Post subject: Reply with quote

du kan prve akustikk i norge. http://akustikk.no/ snakk med Roar Malmin, han kan disse ht. har selv kjpt endel av han.
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speakerguru
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PostPosted: Thu Jan 03, 2008 8:50 am    Post subject: Reply with quote

As far as I can remember the 107 used two paper cone 10" SP1215 speakers in the coupled cavity bass section. What is the SP number of the ones in your systems?

Last edited by speakerguru on Thu Jan 03, 2008 4:50 pm; edited 1 time in total
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Parts
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Location: Edinburgh

PostPosted: Thu Jan 03, 2008 12:15 pm    Post subject: Reply with quote

Do you know who carried the work out on your speakers?

I would do as Speaker Guru says and check the bass driver details, I would also check all the seals and that the force cancelling rod is present and correct.

Wembly Loudspeakers, and I am sure there is another who's name escapes me, may be worth asking, though you may have to post drivers just to find out if they can or cannot be serviced, of course this is dependant on you having the proper drivers.

Once you have determined your drivers as correct or not, you could always ask kef if they have any bass drivers. (My last four cost quite a bit though, and needed some fiddling due to different magnet assemblies, which affect fitting of the force canceling rod.

My own are still work in progress, as I want to relpace all the seals for the cabinet panels, bass drivers etc (Kef didn't supply enough), and fit new grommets and decoupling spacers, IF I ever find somewhere I can obtain the gasket strip, decoupling spacers and such from.

Now regarding your upper bass?

Can you tell me your room size, construction, furnishing and your choice of amplification and ancillaries?

Upper bass performance is slightly different from many direct speakers, but is rather dependent on room and amplification. One old rumour used to be the 107 is easy to drive, but I never have agreed with this, and believe many people have a poor opinion of the 107 due to either hearing them in the wrong enviroment, with inadequate amplification, or without the Kube.

Your description of poor upper bass (lack of punch and definition?) sounds like it could be? a problem with room, positioning, or amplification and ancillaries?
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Parts
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PostPosted: Fri Jan 04, 2008 1:55 am    Post subject: Reply with quote

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Parts
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PostPosted: Fri Jan 04, 2008 1:56 am    Post subject: Reply with quote

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Parts
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PostPosted: Fri Jan 04, 2008 1:57 am    Post subject: Reply with quote

Happy reading Smile
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Parts
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PostPosted: Fri Jan 04, 2008 2:34 am    Post subject: Re: Reccomendations for speaker repairs/serviceing Reply with quote

vistisen wrote:
I have a pair of Reference 107s that I love listeneing to , but as some will know from these excellent forums, I am not satisfied with their upper bass. I know that they have had the drivers replaced at some point, and I think they are the wrong ones. I live in Denmark and know that I am going to have to send them to the UK to be 'looked at'. This is going to cost me serious postage Evil or Very Mad .

Where shall I send them? who knows of a company that will check them, replace drivers, (and 20 year old capacitors!) as necessary. without ripping me off. I wants these speakers to last me 20 years, I love them.


To quote another thread Vistisen,
Your post was most informative, and backs up my first impressions. I can see you have also answered my other post about missing upperbass. As this was experienced using my KUBE 200 in just between the pre amp and the bass amp. It would seem to back up what you say about the KUBE extending up into the midrange driver as well. I have decided to drop bi amping and get better cables instead. One day it will be monoblocks.

Did you ever change from the bi-amped Arcam amps, and did you stick with the original 107 Kube?

Also another quote,
I do not know much about how the drivers were replaced as this was done by the previous owner. But I was told that the new drivers have a rubber mount rather that a foam mount. He did say that it took a whole day to do it!

This seems to indicate a home repair, without original materials (IE foam surrounds and foam inner surround ring or annulus, I would want these fully serviced and replaced proffessionaly by the likes of Wembly if they can do it, or new replacements sourced (my new bass drivers cost 325 for four over a year ago!).
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Ragnar
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PostPosted: Fri Jan 04, 2008 11:06 am    Post subject: Reply with quote

First of all i wish you guys a happy and prosperous new year.

Vistisen, i stumbled across a bass repair facility i southern Jylland. I do not know the company or their competence, but might be worth a try.

Check www.basrep.dk or phone +45 27 21 51 12.

They advertise with bass repairs on many brands, and KEF being one of them.


Ragnar
_________________
Record:
KEF C10's (1986-now)
KEF C80's (1987-2007)
KEF Reference 105's (2006-2006)
KEF Reference 104/2's (2006-2007)
KEF Reference 107's (2007-now)
KEF Reference Two (2007 -now)
KEF Reference Four (2010 -now)
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vistisen
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Joined: 01 Sep 2006
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Location: Denmark

PostPosted: Thu Jan 10, 2008 5:26 pm    Post subject: Reply with quote

Hi and many thanks to all those who have taken the trouble to help!


I got round to taking the top off the speakers to see if I could identify the SP number, as far as I could see there was no identification visible (i didn't dare remove anything more!

My listening room is quite large and L shaped the speaker sit accross the short end of the L which is about 4M by 8M (the other bit is about 4M by 10M) they are almost 80CM from the back wall and about 2,5M Apart.

I don't think that the amps are the cause. I am running them off an Arcam P25 power amp. I tried setting my Kef 104's just beside them and running them off the power amp in the Arcam FMJA22 integrated amp that normally acts as a pre amp. It was very interesting the 107,s had much more deep bass, but the 104s showed just how much upper bass was missing.

Special thanks to Ragnar. I will be ringing basrep tomorrow Very Happy

Fascinating to see so many Scandinavians her in the forum. I don't know about Sweden and Norway, but here in Denmark there are not many shops that sell the larger Kef Speakers. [/img]
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Parts
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PostPosted: Thu Jan 10, 2008 10:12 pm    Post subject: Reply with quote

vistisen wrote:

I got round to taking the top off the speakers to see if I could identify the SP number, as far as I could see there was no identification visible (i didn't dare remove anything more!

My listening room is quite large and L shaped the speaker sit accross the short end of the L which is about 4M by 8M (the other bit is about 4M by 10M) they are almost 80CM from the back wall and about 2,5M Apart.

I don't think that the amps are the cause. I am running them off an Arcam P25 power amp. I tried setting my Kef 104's just beside them and running them off the power amp in the Arcam FMJA22 integrated amp that normally acts as a pre amp. It was very interesting the 107,s had much more deep bass, but the 104s showed just how much upper bass was missing.[/img]


Hi Vistisen,

I believe the seriel number/drive unit number are on the side of the magnet, you would have noticed a bolt through the middle of this units magnet assembly?

I still am not convinced the Arcam is all that suitable, its current delivery into 4ohm may not be enough?
As an example, I have used a Technics SU-MA10 integrated amp (100w), and a NAD C162/C270 pre/power amp with the Kef R-107, with and without Kube.
Both were limited in upper bass punch and lower bass control and definition, the Technics more than the Nad.
The Nad was better than the Technics, it had 120w into 8ohm, 210w dynamic power into 8ohm (340w into 4ohm dynamic).

Both amps would switch off or clip (though Nad had soft clipping) at highish output or with dynamic LF content. Both lacked mid bass punch.
I used this Nad power with an Audio Research valve pre for a short while, the Nad power sitting on a Mana refrence table. Fine as a stop gap, but it never really got the Kef 107 singing.

There was one day, I remember my wife, arms crossed, giving me one of those looks, when I brought a small concrete slab into the sitting room, plonked it on the floor, came in with some wires, then out and back in with the Classe CA-100 power amp. An older, and to some uglier, power amp than the NAD, with 100w into 8ohm, 200w into 4ohm. She gets annoyed at my box swapping and how ugly some of the kit is, I think she sometimes forgets what is in some of the cuboards too.
Well after a few months of that Nad sitting there, she had pretty much got used to it's sound, sufficed to say, when I fired up the Classe, and said 'do you hear' that, she just nodded and accepted it with a smile. Mid bass punch and definition were in a completely different league, low bass had more control and detail.

Seriously, some people think of amps like the Nad having good capabilities and output, but the 107's love current, drive, control and having it makes a big difference to bass quality, regardless of watts. The 107's have some myth about being easy to drive, but I think thats ok if you do not mind being assaulted by oversize marshmallows.

I do think I know what you are experiencing. When I used the Technics or Nad set up, whenever I changed my speakers to my Kef 105.4 I got better mid bass punch. And right now I am experiencing a lack of mid bass punch, as I am not using my usual pre/power, I know things will be better when I re-introduce my usual set up though.

Here is an old pic of the old Audio Research and Classe combo.



And here is another old pic where you can see the NAD pre power dumped on the floor.



Nice to add a bit of colour with a couple of pics Smile
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Ragnar
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PostPosted: Sun Jan 13, 2008 11:29 pm    Post subject: Reply with quote

Although i am a hifi nut myself, i can see the situation from your wife's point of view. You do have a lot of boxes !

Anyway, interesting to hear that there is a noticeable difference between the Classe and the other amps.

I will do some testing myself.

Luckily i got the opportunity to purchase a pair of 104/2's just before christmas for a favorable amount. All drivers were OK, but the exterior was not in top shape. I replaced the front cloth and cleaned and oiled the casings. Now they look almost like new.

If any of you guys should need new front cloth, i can obtain some at a very good price.

I paid about 4 GBP for the cloth to the 104/2's (180 cms X 100 cms).


Ragnar
_________________
Record:
KEF C10's (1986-now)
KEF C80's (1987-2007)
KEF Reference 105's (2006-2006)
KEF Reference 104/2's (2006-2007)
KEF Reference 107's (2007-now)
KEF Reference Two (2007 -now)
KEF Reference Four (2010 -now)
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Ragnar
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Joined: 02 Feb 2007
Posts: 35
Location: Sweden

PostPosted: Wed Jan 16, 2008 4:20 pm    Post subject: Reply with quote

I came across this graphic presentation of the 107 response to the various frequncies.

It shows a noticeable dip at - 3 dB at 160 Hz.

I can not answer for the validity of this presentation, but does'nt it correspond quite well to what Vistisen experiences ?

I have the same impression of a "lack of punch" in the upper bass area myself.

http://www.linkwitzlab.com/images/photos/power_response-s.jpg

Generally speaking the website seems to be quite useful

http://www.linkwitzlab.com/


Ragnar
_________________
Record:
KEF C10's (1986-now)
KEF C80's (1987-2007)
KEF Reference 105's (2006-2006)
KEF Reference 104/2's (2006-2007)
KEF Reference 107's (2007-now)
KEF Reference Two (2007 -now)
KEF Reference Four (2010 -now)
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Parts
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Joined: 13 Jan 2006
Posts: 174
Location: Edinburgh

PostPosted: Wed Jan 16, 2008 8:36 pm    Post subject: Reply with quote

Ragnar wrote:
I came across this graphic presentation of the 107 response to the various frequncies.

It shows a noticeable dip at - 3 dB at 160 Hz.

I can not answer for the validity of this presentation, but does'nt it correspond quite well to what Vistisen experiences ?

I have the same impression of a "lack of punch" in the upper bass area myself.

http://www.linkwitzlab.com/images/photos/power_response-s.jpg

Generally speaking the website seems to be quite useful

http://www.linkwitzlab.com/


Ragnar


Hello Ragnar,

If you look at one of my previous posts, the one of the review, it mentions this as the crossover point, this point and below is where the contour works.

Now due to the head, lower bass cabinet interaction, I would question any measurement which has no description of how it was achieved, nor does it mention the kube in circuit or not? Then again, it is not unusual to see such dips at the crossover points of many speakers.
Kef also state a +-2db across the frequency range of the R107.

I myself only notice this dip/lack of midbass with poor amplification with a lack of current/drive capability.

A couple of things to try, rigid coupling to the floor with spikes, a concrete or marble slab, or even try fitting spikes to the front and raisnig the rear by keeping the feet on?
I myself will be trying my Kef on Mana soundbases later.

Superb find though Ragnar, definitely food for thought.
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vistisen
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Joined: 01 Sep 2006
Posts: 57
Location: Denmark

PostPosted: Sun Jan 20, 2008 3:12 pm    Post subject: Reply with quote

Hi,

I thought I would post an update, I rang basrep as suggested by Ragnar. They were most helpful. My Arcam amp would seem to be more than capable according to them (it does have an output of over 25 amps). They suggested measuring the resistance of the bass drivers to see if they are originals. Kef units should, according to them have a 6ohm resistance (when measured accross the terminals on the driver) This I have not yet done. Everything takes a long time with me, just ask my wife how long it took to paint the bathroom Laughing. They suggested that if the speakers have needed to have new bassunits then the midrange drivers might also be damaged.
I have tried to find out just where (and how big my frequency "hole" is using a Test CD with sine waves and sound pressure meter I got the following shock. a 100Hz sinewave was more than 8 dB quieter then a 50 Hz or a 200Hz sine wave when measured from the normal listening position. Shocked No wonder I can't hear the upper bass. Unfortunately the test tones are not more finely graduated. I have had a go at programming my old Korg keyboard to produce a pure sinewave with no keyboard sensitivity to give me a better idea of the actual size of the hole. The sound drops of rapidly at F3 which is 174 Hz, it is about 8Db quieter then F#3 which is 185 Hz. It is at least 8 db quieter down to B1 61.74 Hz when it is suddenly "back" and then continues flatish down to A0 (27,5 Hz Wink ).
As far as I can see the crossover frequency between the bass and midrange is 160 Hz, so the main suspect is still the bass drivers. Right from the start I said that the bass driver rolled off too low and too quickly, this seems to be supported by my very rough puesdo scientific experiment. I think I will have to get some new ones from Kef
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