• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Amplifier recommendations for vintage KEF 105.1

Because of the Superposition Principle.

S.
Ah - I did not know about this. Hence my original question. I tried reading up about it, but the heated arguments about it here and elsewhere did not really explain it. Still not quite understand why it does not matter for an amplifier how many separate speaker drivers it has to run.

But to reiterate, if anything I should use my Luxman as a pre only ( or one of the others) and then one dedicated power amp.
 
Last edited:
405?

We were a higher end dealer and, just before we staff asked Naim and Linn to get their claws into us, the Crown D-150A drove them superbly.

Today and assuming the crossovers and drivers haven't drifted off as I gather they can (wasn't there a HiFi news test of a vintage pair compared to test results of a new set?), any decent 100WPC+ amp should do well, the modern class D types available now for well under £/$1000 a perfect choice I'd suggest.
Crown amps were great at the time, although very few dealers stocked them. HH amps would also do a good job into 105s, as would Hafler and several others. They weren't a severe load, so many amps were happy driving them. These days, I agree that a modern Class D amp would be the most effective.

S
 
What bollocks!
Firstly, the 105 was never fitted with dual input sockets, as the crossover wasn't split.

Secondly, the crossover is integral to the loudspeaker and isn't available externally without taking the 'speaker apart, so turning it active isn't an option without a great deal of DIY.

I don't know why anyone would ever ask anything of Chat GPT, as it seems to get so much wrong, so can't be trusted with any answers.

S.



The 105.1 has dual input sockets as the lower bass section has it own crossover board in the bass cabinet. As does the mid/tweeter.

However the top head has a set of terminals and also a set of soldered leads with factory plugs that plug into the lower bass terminals as a link.

Would not say it was designed to be bi-amped and there is no reference of this in KEF the 50 years of innovation book (excellent read)

The 105.2 has the crossover for all drivers located in the bass section and uses a multi plug type connector from the top head into the lower crossover.

Originally the kef heads were made out of wood,but they do crack eventually and were labour intensive as was the 105.1 cabinets.

KEF moved onto a plastic type head,smaller cabinet,bass driver decoupling( 3-point) and a smaller more wife friendly cabinet.

Have 105.1 and 105.2 and they are fantastic speakers,even in the company of ns1000 and 801fs...
 
The 105.1 has dual input sockets as the lower bass section has it own crossover board in the bass cabinet. As does the mid/tweeter.

However the top head has a set of terminals and also a set of soldered leads with factory plugs that plug into the lower bass terminals as a link.

Would not say it was designed to be bi-amped and there is no reference of this in KEF the 50 years of innovation book (excellent read)

The 105.2 has the crossover for all drivers located in the bass section and uses a multi plug type connector from the top head into the lower crossover.

Originally the kef heads were made out of wood,but they do crack eventually and were labour intensive as was the 105.1 cabinets.

KEF moved onto a plastic type head,smaller cabinet,bass driver decoupling( 3-point) and a smaller more wife friendly cabinet.

Have 105.1 and 105.2 and they are fantastic speakers,even in the company of ns1000 and 801fs...
Thank you for the informed post :)
I have sourced a large power amp to drive them (a NAD 218) so I do no longer look at the bi-amping option. All that remains is some restoration.
I just learned that the tweeter in the 105.1 does not use ferrofluid. So that is one thing less to fiddle with.
 
Thank you for the informed post :)
I have sourced a large power amp to drive them (a NAD 218) so I do no longer look at the bi-amping option. All that remains is some restoration.
I just learned that the tweeter in the 105.1 does not use ferrofluid. So that is one thing less to fiddle with.


Fyi the t52 is also in the meridian m2 another excellent speaker,worth having an eye out for spare t52s.

According to the kef book they were difficult to manufacture....

Here are some i restored and plenty of info on these fantastic speakers .https://pinkfishmedia.net/forum/threads/kef-105.288579/

Have had a Quad 405 on them which was period correct and now use a Quad 909 140wpc.
 
May as well update this thread, rather than starting a new one, as I too have recently acquired some KEF Reference 105.1 speakers. The twist, is that I have acquired the pair that started the thread four or so years ago. I hope the drive yesterday wasn't too badly impacted by the weather fordiebianco!

2025-01-04_163302584.RAW-01.COVER.jpg


This all came around a bit unexpectedly, as I wasn't expecting to purchase any equipment till the summer. Going through an amicable separation, and wanted to get all of that out of the way before getting into anything. I had thinking along the lines of a Cambridge Audo Evo 75, with something like the Q Acoustics 5040's. Due to the separation though, I thought I should see if I could make my money go a bit further, and started looking at what was around on eBay, and here we are.

I currently have a Rega Planar 3 and Fono MM Mk5, and a decent collection of vinyl. Plus there is a vast array of ripped CDs sitting on a NAS, and a few 24 bit downloads that have come with vinyl purchases of late. What ever I end up going with, I need to be able to listen to both the vinyl and the ripped CDs.

I've always wanted some large cabinets, preferably with a meaty pair of monoblocks sitting next to them. While I know that the monoblocks are superfluous, mostly for the looks and a decent integrated amplifier would do me fine, the heart wants the monoblocks. I briefly looked at the 2024 Quad 33 and 303 reissues, noting that the 303's are now properly bridgeable, but £3.5K the set of three is too much for me at the moment. There are plenty of classic Quad 303's going for £200 on eBay though, and according to the internet, they can be driven* in serial or parallel, to make a 90W single channel amplifier. There's even a really poor quality scan of a document from Quad showing how to do it - https://dadaelectronics.com.au/doc/Audio/Quad/Quad 303/Q 303 bridge.pdf

So first question, is running a pair of vintage Quad 303's in serial mode, a daft idea...? Given that the PDF states 90W into 16Ω, and these are 8Ω? Let's ignore the fact that I canny understand what's actually involved in the modification either...

I also looked around for some sort of integrated amplifier, given that Quad 303's would probably also require the purchase of a Quad 33 or 44 preamp and a streamer. eBay turned up a Mission Cyrus 2 + PSX that I could afford, even with an immediate service from ASR. I contacted the seller and he says he's not had it serviced and he's not the original owner, no boxes or instruction manuals. There has been some discussion of this amplifier on here, and other forums, and it leaves me with the impression that maybe this isn't the amplifier for that big cabinet? It would also require a streamer or some sort.

I know I can indulge in some monoblocks by getting a pair of the Fosi V3 Mono's, but I would still need some sort of streaming preamp to supply them with. A WiiM Ultra might do the job, as it appears to have extra inputs for this kind of thing?

It might just be easier to get a just add speakers streaming amplifier, like the Cambridge Audio Evo's, but one that wouldn't break the bank, like the Naim Uniti Nova PE. Does such a thing exist in the world of Fosi, SMSL, Topping, etc?

Open to any thoughts and suggestions.



* Threads on other forums where this is discussed:
 
I still have a refurbished set of Quad 33/303. It was a brilliant design at the time, but I would now avoid it. My advice would be a WiiM Ultra as a preamp/DAC/streamer with all the necessary analogue and digital inputs and dsp room equalization. For a power amplifier I would opt for a modern class D one based on e.g. a Hypex module. These speakers will like some real power. Get one with auto on/off and you can place it out of sight for clean esthetics.
 
The kef 105.1 need a bit of power due to the crossover design.
The period relevant amplifier is a 405 and they can be picked up rather cheap it will drive them.
If u want to add a 303 again cheap and as will the Peter walker period designs full circuit diagrams and repairability.
The new quad stuff is not going to last like the origional stuff,and is nonsense money.
Another option is a 909 which is an excellent powerhouse and not silly money.
I use one in another system.
 
The kef 105.1 need a bit of power due to the crossover design.
The period relevant amplifier is a 405 and they can be picked up rather cheap it will drive them.
If u want to add a 303 again cheap and as will the Peter walker period designs full circuit diagrams and repairability.
The new quad stuff is not going to last like the origional stuff,and is nonsense money.
Another option is a 909 which is an excellent powerhouse and not silly money.
I use one in another system.
I use a refurbished Quad 606-2 (an earlier version of the 909 and successor to the 405) in my main system and either the 606-2 or the 909 would be my preference for a period correct amp. However, make sure that you match the high input sensitivity to the higher output of modern DACs etc. Personally, I would now go for a Hypex/Purifi based class D amplifier.
 
Last edited:
I use a refurbished Quad 606-2 (an earlier version of the 909 and successor to the 405) in my main system and either the 606-2 or the 909 would be my preference for a period correct amp. However, make sure that you match the high input sensitivity to the higher output of modern DACs etc). Personally, I would now go for a Hypex/Purifi based class D amplifier.
+ 1 for the Quad 405 at the time this was the amp of choice as used by Kef at all the Hifi shows back then
 
Superb speakers, one of my all-time favourites.

Would not recommend a QUAD 303 or 405 for them. 405 will work but they're really not so great.

I'd avoid the '33' pre-amp. Aside from anything it needs modifying to accept 2 volt input.

Get some modern amplification for them.
 
The later 405-2 will be OK, but the 606-2 and 909 with toroidal transformers (not the 606) are much better. The 33 preamp was clever but indeed is now outdated.
 
Thanks everyone, much appreciated. I love the idea of going period appropriate, I'm just not sure if it's what I'll actually be happy with. Finding examples that look decent in a condition is proving slightly out of my budget, i.e. the ones that have been serviced and re-capped are too much, but the cost of buying, then having one serviced and re-capped is probably also too much. Lots of the Quad 44 / 405 combos, also seem to come with the FM tuner, which I don't want. Although like the 303's, evidently to 405's can be run in that serial / parallel mode for more power too...

As I'm in the UK, I had a look at the Nord Acoustics website, as that seem to be the place to go for Hypex / PuriFi, etc. I'm not sure I really understand the difference between them, other than one seems waaaaaay more expensive than the other. The Nord Value-Line MP NC252 at £349 is 2 x 150Wrms into 8Ω, while the next one up, the Nord Value-Line MP NC502 at £519 sees a ridiculous 2 x 350Wrms into 8Ω. Their cheapest PuriFi based one, the Nord Three 1ET400A is 227W into 8Ω, but is over £1,000.

When you all say that these speakers need some power, what are we talking about here, as the vintage Quad's are all relatively modest in comparison...?
 
Thanks everyone, much appreciated. I love the idea of going period appropriate, I'm just not sure if it's what I'll actually be happy with. Finding examples that look decent in a condition is proving slightly out of my budget, i.e. the ones that have been serviced and re-capped are too much, but the cost of buying, then having one serviced and re-capped is probably also too much. Lots of the Quad 44 / 405 combos, also seem to come with the FM tuner, which I don't want. Although like the 303's, evidently to 405's can be run in that serial / parallel mode for more power too...

As I'm in the UK, I had a look at the Nord Acoustics website, as that seem to be the place to go for Hypex / PuriFi, etc. I'm not sure I really understand the difference between them, other than one seems waaaaaay more expensive than the other. The Nord Value-Line MP NC252 at £349 is 2 x 150Wrms into 8Ω, while the next one up, the Nord Value-Line MP NC502 at £519 sees a ridiculous 2 x 350Wrms into 8Ω. Their cheapest PuriFi based one, the Nord Three 1ET400A is 227W into 8Ω, but is over £1,000.

When you all say that these speakers need some power, what are we talking about here, as the vintage Quad's are all relatively modest in comparison...?


We had a set of the 105 at a meet a couple of years back, lots of amplifiers there pretty much all of them got coupled to the 105 at some point. IMO the best result was with a Musical Fidelity A5 (250wpc) but we also got good results with a vintage Technics at 100wpc.

This was in a very large room (cricket club) and with heavy rock, nothing easy.

In a normal size UK living room I think you'd get away with 50 watts.
 
A couple one of these vintage NAD 2200 might be just the ticket. IIRC @EJ3 is an expert on them, ~$400 ea on eBay
 
Back
Top Bottom