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Should I replace my KEF 105.1's?

sergeauckland

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If the drivers and crossovers are still in good condition, keep them. You will need to spend a lot of money to get anything better.

That would be my suggestion also.

If you fancy a DIY project, you could make the 105s active by disconnecting the internal passive crossover, and using an external DSP-based crossover and 6 channels of amplification. I did this with my B&W 801s, although I wonder if 105s would have been just as good or possibly even better. I had a pair of 105.2s on loan for some time, and really liked them.

If that's a step too far, you could try an external DSP-based equaliser and set them up for a flat on-axis pseudo anechoic response, then tweak for the best in-room response. Unless you're in the habit of playing very loudly, 105s have plenty of power handling so any boost due to EQ shouldn't detract from headroom to any significant extent except possibly at LF, but then I wouldn't try and fill any deep room nulls with EQ.

Lovely 'speakers.

S.
 

DSJR

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Looks like keepers.

Get new/modern drivers with less dist, biamp/triamp the speaker and play with xover settings with your DSP.

Perhaps add a microphone to measure an averaged FR in the listening area.

That sounds like a fun project.

I think you'd find the 105 drivers *as used* to be still superior to many made today, but the 105 crossover may need a looking at for drifting caps (I don't remember the crossovers as we never dismantled any to find out, but worth researching perhaps).

Apart from a slight cool quality on female vocals (my subjective description), these speakers were very high quality indeed, especially for the time and they measured well and properly by anyone's standards as indeed they should with the considerable R&D that went into them. Messing around with trying to go active and so on with amateur levels of DSP eq and all manner of 'stuff' on the back of them to try to make it work, I'm really not sure about! I'd sooner look at a good powerful modern amp with a couple of hundred Watts at 8 ohms minimum to let them breathe a bit and a clean source to exploit the potential performance I still think they can offer.
 

Angsty

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If the drivers and crossovers are still in good condition, keep them. You will need to spend a lot of money to get anything better.
Agree. One issue I’d consider with 40-year old speakers is the condition of the electrolytic crossover capacitors. These capacitors tend to go off spec as they age and that aging issue is less obvious than driver surround aging. If you have a good repair shop that can test this, it may be worth checking.
 

redshift

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I think you'd find the 105 drivers *as used* to be still superior to many made today, but the 105 crossover may need a looking at for drifting caps (I don't remember the crossovers as we never dismantled any to find out, but worth researching perhaps).

Apart from a slight cool quality on female vocals (my subjective description), these speakers were very high quality indeed, especially for the time and they measured well and properly by anyone's standards as indeed they should with the considerable R&D that went into them. Messing around with trying to go active and so on with amateur levels of DSP eq and all manner of 'stuff' on the back of them to try to make it work, I'm really not sure about! I'd sooner look at a good powerful modern amp with a couple of hundred Watts at 8 ohms minimum to let them breathe a bit and a clean source to exploit the potential performance I still think they can offer.

Perhaps you take stuff a bit too seriously?

It is not exactly impossible to put them back into original condition if the ‘souping up’ attempts fail. I’m not suggesting putting a sledgehammer on the cabinets to bash out a few kinks with the fidelity.

The speaker is rather old after all. Don’t get me wrong though, it is nothing inherently wrong with that. Technology moves forward after all.

And besides, with a prosumer/pro DSP you can do much more than just obsess over ruler flatness. Like play with loudness curves and effects until you get a silky smooth sound.

That is of course difficult to achieve if the drivers spew distortion due to age and limitations of the tech of an era.
 

fordiebianco

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I own a pair. Bought them last year for very little money due to water damage (they stood in wet loft for 20 years). Had the crossovers upgraded and the drivers checked, used a bit of furniture oil and hey presto: gorgeous, amazing sounding floor standers. Please don't sell them. Maybe get a modern pair of speakers home to compare them, but I find it unlikely that you will find something better without spending a lot of money. Get them serviced though, by all means.
 

DSJR

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Not sure if anyone's interested, but I could scan the original 'Choice review (it was our dem pair being measured in this instance) and post it.
 

sergeauckland

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Agree. One issue I’d consider with 40-year old speakers is the condition of the electrolytic crossover capacitors. These capacitors tend to go off spec as they age and that aging issue is less obvious than driver surround aging. If you have a good repair shop that can test this, it may be worth checking.
I agree, recently recapped a pair of original B&W 801s for a friend, where the bi-polar electrolytics had drifted in value after 40 years.

Bi-polar electrolytics are effectively two normal polarised electrolytics back-to-back, and consequently neither 'half' gets any polarising voltage. Electrolytics have the longest lifetime when they're polarised correctly, so using them as non-polars seems to affect their life.
Fortunately, they're quite cheap, so replacement won't be expensive.

Plastic film capacitors have far longer lifetimes, but in the voltage and capacitance needed for passive crossovers are both physically large and expensive, so may not be a straight fit. In any event, a plastic-film capacitor will have different impedance characteristic, so won't necessarily provide the same performance as the original electrolytic. Crossover inductors will be fine, as these don't have any wear mechanism unless grossly overloaded, and anyway they're hard to replace as crossovers tend to use fixed value capacitors and inductors custom wound to provide the right inductance.

Crossover resistors can degrade, especially if overheated, but these are easy to measure with a normal ohm-meter. On the 801s I recapped, all the resistors were in tolerance, but a couple were close to the edge, so were replaced. Again cost was pennies.

S
 

DSJR

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As threatened, here's the HiFi Choice review done by Martin Colloms. This is from a very well thumbed book and page colour is authentic :D

Just above the mid driver and in the bottom of the tweeter part of the 'pod,' there was a red led inset with a control on the back for setting power levels before the lamp flashed. I believe the inset led helped with setting the angle of the 'pod' which was adjustable for tilt and lateral angle for 'listening axis' I remember. This really was a very serious 'proper' loudspeaker back then and considerably ahead of the rest apart from possibly the B&W 801 which I don't think was 'quite' as good in initial form (I have a deep suspicion of the intrusive sonic qualities of the protection system with push buttons just in front of the mid driver on the 801 that was incorporated into the posher speakers of these times - and promptly abandoned a season or two later as my pal's later issue 801 pre Matrix cabinet doesn't have them... If Serge is interested, I also have the review in the following issue of the 105.2 with decoupled bass driver and refinements further up (not sure how much rock music was used in the listening sessions at the factory...)

scan0003.jpg
 
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DSJR

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1978

Hell, the mag has all but fallen apart as I removed it from the scanner - I did say it was well thumbed ;)
 

redshift

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1978

Hell, the mag has all but fallen apart as I removed it from the scanner - I did say it was well thumbed ;)

Scan it and print out a copy which you whack in the toilet bookshelf.

Only illiterate savages have toilets without a bookshelf.

:D
 

DSJR

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The 105.2 test was the following year - this time span an eternity when I was twenty two years old, but a split second duration today...

Main obvious difference was the veneered bass front baffle, decoupled bass driver in revised three point chassis and other changes I'm not up on to integrate it all better - I seem to remember the led and control on the back disappeared. I think we'd drifted over to the smaller? 105.4 as the bass was better for rock music, but not sure how that would translate from a bank of speakers in a dem room to a client's home (may 'thump' too much possibly)
 

redshift

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As threatened, here's the HiFi Choice review done by Martin Colloms. This is from a very well thumbed book and page colour is authentic :D

Just above the mid driver and in the bottom of the tweeter part of the 'pod,' there was a red led inset with a control on the back for setting power levels before the lamp flashed. I believe the inset led helped with setting the angle of the 'pod' which was adjustable for tilt and lateral angle for 'listening axis' I remember. This really was a very serious 'proper' loudspeaker back then and considerably ahead of the rest apart from possibly the B&W 801 which I don't think was 'quite' as good in initial form (I have a deep suspicion of the intrusive sonic qualities of the protection system with push buttons just in front of the mid driver on the 801 that was incorporated into the posher speakers of these times - and promptly abandoned a season or two later as my pal's later issue 801 pre Matrix cabinet doesn't have them... If Serge is interested, I also have the review in the following issue of the 105.2 with decoupled bass driver and refinements further up (not sure how much rock music was used in the listening sessions at the factory...)

View attachment 142173

Then it’s barely broken in. New caps and OEM drivers, watch it chug along until the end of the century.
 

DSJR

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Forgive these anal responses, it's just that I don't think many here will be familiar with these, at least at the time of production in the late 70's to mid 80's. HiFi Choice back then was in a bi-monthly? book form with copious group tests and the speaker books were at least one or maybe two per year. KEF didn't rest on their laurels as production went on and little tweaks were done at times I believe. I think by the time of the tall 105.7 with active bass eq box, 'Choice had moved over to a monthly larger format magazine same as everyone else.

Here's the 105.2 and 105.4 for completeness. I think the 1.5.3 was a Uni-Q model and there was a big splash when it first appeared some years later.

scan0005.jpg


scan0006.jpg
 
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YSC

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So the jury is pretty clear that these kef’s doesn’t deserve being flipped, rather restored to factory new spec?

View attachment 142201

:cool:
I would say so, if able to add a sub to tame the room modes with the sweet spot and the aligned phase design I can't see changing to a new speaker can result in significant perceivable improvement, except mentally coz you spent a fortune
 

redshift

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I would say so, if able to add a sub to tame the room modes with the sweet spot and the aligned phase design I can't see changing to a new speaker can result in significant perceivable improvement, except mentally coz you spent a fortune

So > $2k USD to get them (+sub) shredding better than brand new then?
 
OP
D

Don105

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OK - interesting discussion, thanks everyone for their input. There seems to be a majority opinion that I should a) measure to make sure they are working correctly b) if not, possibly service the crossovers c) look at getting better amplification.

- I will definitely look into the suggestions about getting a calibrated mic and appropriate software and measuring the 105's response in my room. Is this the mic you'd all recommend? https://www.minidsp.com/products/acoustic-measurement/umik-1?lang=en
- I just found the REW software home page so will look at that. looks like it will run on my Mac laptop so that's good.
- I can't see or feel any damage to the drivers - just removed the grills on one speaker, there is no friction when I very gently move the cones on the woofer and mid-range. and no mysterious fluids dripping out :). I'm scared to mess with the tweeters but they look fine through the grills.
- Assuming I find a problem that could be attributed to the crossovers.... I'm not sure what is involved in opening up the KEFs to get to them, without damaging the cabinets. If anyone has done this or knows someone who has done this, and could provide guidance, please let me know. Or if anyone knows a shop in Los Angeles that would re-cap the crossovers for a reasonable cost, let me know...
- I will look into replacing my amp with something with more power. I actually have a Nakamich 620 power amp that's been sitting idle for many years. It is 100wpc but perhaps better quality than my Sony STR-DN1040? I have no idea. I also have the matching 630 tuner/preamp but it needs servicing (noisy potentiometers). maybe just some tuner spray but that's a whole project to figure out how to take it apart (and put it back together). Though I think I have the service manual somewhere.
- If there are major problems with the room acoustics then it seems there is a whole new adventure required to look into the world of equalizers and associated equipment...

Don
 
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