Question about amp & speaker ohms

[MKF]

Hi all, Proud new owner of a very clean pair of KEF 104/2 speakers. Question for the tech experts....so these speakers are 4 ohm and I have two vintage 8 ohm amps/receivers. 1st is a Luxman R-1050 and the second is an Onkyo TX6500 mkii. The Onkyo is a beast and I love it, however, my heart is with the warmth that the Luxman creates.

My question...are both these amps fine to power these speakers? I understand they can truly sing when the power and wattage from the amp is high, however, I won't be listening to them at that kind of volume and am hoping neither amp will have a risk of getting hot. When my wife is out the volume definitely goes up, but still...nothing that will wake the dead.

Thanks in advance for sharing your thoughts. I fully expect I may get many differing replies, but hopefully the consensus will agree that both amps will be sufficient to power the speakers and I can choose my preference.

 

[justjed2]

My general advice goes something like this:

1: Hook up you amp, and power up the system.
2: Turn it up until it starts to sound crappy.
3: Note WHERE on the dial this occurs, and turn it down to your preferred listening level.
4: Don't turn it up that loud again. You, your amp, and your speakers will be fine.

 

[JoeESP9]

Does it say anywhere on either amp or its manual say no 4 Ohm speakers? Probably not. Even if it does, it's safe to follow the advice from @justjed2.

PS: If neither amplifier has enough power for the levels you want, buy more power. The 104.2's are IMO very good speakers.

 

[opnly bafld]

Hi all, Proud new owner of a very clean pair of KEF 104/2 speakers. Question for the tech experts....so these speakers are 4 ohm and I have two vintage 8 ohm amps. 1st is a Luxman R-1050 and the second is an Onkyo TX6500 mkii. The Onkyo is a beast and I love it, however, my heart is with the warmth that the Luxman creates.

My question...are both these amps fine to power these speakers?

Both are okay running 4 ohms, look on the back by the speaker terminals.

 

[MKF]

Both are okay running 4 ohms, look on the back by the speaker terminals.

You, my friend, are exactly what I needed and you are spot on! I didn't see that note as I disconnected my old speakers and wired up the KEFs at the speaker end rather than at the receiver's end and therefore didn't see the sticker. Thanks!

I know it is always a matter of preference, but I am curious to hear others thoughts on which of the two amps/receivers paired with the KEFs? I love the warmth of the Luxman and coupled with the warmth of a pair of British made KEFs it has me in its grip, which I guess answers my own question as it is me who is playing it. However, the Onkyo is a killer amp too, but it is definitely much "brighter", which isn't bad...just different.

 

[rickb119]

I love the warmth that my B&K amp delivers to the KEF's. I did try my Sansui AU-919 (for a brief period, since it's not rated for 4 ohms). It too was much brighter than the B&K. It plays well with other speakers that I have though.

 

[BilboBaggins]

Welcome to Audio Karma!

I love these threads because I started my return to audio journey with a pair of Celestion Ditton 66 speakers, another family of 4 ohm speakers. They were the start of my audio journey again, and led me to maxing out my credit cards before I discovered the direction I needed to go in. I've had many of them since, and I'm also a die hard Kef lover. I've gone through the ranges of 104aB, Concerto, 104/2, 105, and now 107s. They will sound fine with either the Luxman and the Onkyo.

You can get away with it for a while, but eventually something will happen, and you will wonder why you spent all those years listening to the speakers in a choke hold. Yes, they will sound good. But they can sound so much better!

True story! I had the Kef 104/2 and Kef 105 at the same time. I had really wanted the 105s, but found the 104/2s first. Then two weeks later, I found the 105s. After extensive listening (they were pretty well equal with strengths on both sides), I decided to let the 104/2s go. A good friend of mine was over and saw them. He actually had them back in the early 80s and had to sell them to pay his crack dealer. Along with his Nakamichi Dragon, etc. He quit crack cold turkey following that escapade. When he saw mine, he told me he wanted them. So he brought them home and connected them to his Onkyo receiver. They sounded fine, but every time I went over there, I was reminded of how much better they could sound. Back in November, his Onkyo died(hmmm, I wonder if the 4 ohm load had anything to do with that? ). So he called me and asked me what he should get. I told him he could get vintage, but I didn't recommend that for him. I suggested he look at Bryston, Emotiva, and a few others. He decided to get an Emotiva preamp and power amp. I was over there in early January, and those 104/2s sounded great! I had forgotten how good they sounded. He told me that night that he wished he had done that years ago.

My advice? Don't be him.

 

[MKF]

Welcome to Audio Karma!

My advice? Don't be him.

Ha! I'll try not to be.

I admit I am a sucker for older equipment. It probably goes back to being a child of the 70s and falling in love with records as a young kid and wanting to one day own a Garrard TT and Pioneer receiver like my parents. No longer am I wishing for that Garrard, but I have owned Pioneer TTs and Receivers in the past and do like some of them.

The best modern gear I have owned was an Arkam amp and it was fantastic. Far better than a Cambridge Audio I once owned. But, I still prefer both the Luxman R-1050 and the Onkyo TX6500 over both (sonicly and aesthetically).

Serious question for ya....the KEFs were made in the mid-80s....they would have been made with both 70s and 80s high end gear in mind. Why do you think a late 70s quality receiver/amp such as the Luxman and Onkyo is good, but not great when paired with these speakers? I'm not technical, but I have read these speakers do indeed sing with more power such as a 100 or even 200w, but I tend to go with what my ears like and I am also a sucker for aesthetics and a lot of older hifi equipment appeals to both my ears and eyes.

PS: the bass and midrange on these KEF 104/2s is out of this world!

 

[BilboBaggins]

Ha! I'll try not to be.

I admit I am a sucker for older equipment. It probably goes back to being a child of the 70s and falling in love with records as a young kid and wanting to one day own a Garrard TT and Pioneer receiver like my parents. No longer am I wishing for that Garrard, but I have owned Pioneer TTs and Receivers in the past and do like some of them.

The best modern gear I have owned was an Arkam amp and it was fantastic. Far better than a Cambridge Audio I once owned. But, I still prefer both the Luxman R-1050 and the Onkyo TX6500 over both (sonicly and aesthetically).

Serious question for ya....the KEFs were made in the mid-80s....they would have been made with both 70s and 80s high end gear in mind. Why do you think a late 70s quality receiver/amp such as the Luxman and Onkyo is good, but not great when paired with these speakers? I'm not technical, but I have read these speakers do indeed sing with more power such as a 100 or even 200w, but I tend to go with what my ears like and I am also a sucker for aesthetics and a lot of older hifi equipment appeals to both my ears and eyes.

PS: the bass and midrange on these KEF 104/2s is out of this world!

Great question MKF!

First of all, I am a big fan of of vintage 70s and early 80s gear. My main gear is comprised of 2 X Bose 1801 power amps, a Bose 1801 Preamp, a McIntosh MC2205, a McIntosh C26. I love that vintage gear! I find it is built better than most other gear I can afford.

I think two things explain why power amps tend to drive 4 ohm loads better than receivers or integrated amps. The capacitors and the power transformer. The bigger they are, the better the amplifier seems to drive bigger drivers with control. Please also note that I went through a McIntosh MAC1900 and a fully restored Sansui 9090 before I found a Kenwood Supreme 500. I was searching for "the sound", and they weren't cutting it with the speakers I like. My first main speakers that stayed are the Kef Concerto. These are such beautiful sounding speakers! Especially with the Kenwood Supreme. But they are a 4 ohm load. My son has them now, and he was using a Kenwood Basic M1A to drive the Celestion Ditton 44s I gave him (another 4 ohm load), and it just barely does it with the Kef Concerto he has now. I can hear the difference, being intimately familiar with them. Their only problem is that they just barely go loud enough for the house. I also like cranking it up so they will be heard outside. They couldn't do it.

The Kef 104/2s can do it. But they need to be fed lots of clean power, and power amps tend to use larger trannies and caps. They have the space, and client expectation. Remember that in the 70s and 80s, clients expected receivers to be the cheapest, then integrated amps, and then power amps to be the most expensive. There are always exceptions, but not that many. My Bose 1801 weighs 88 lbs, the same amount as my McIntosh MC2205. If you look at the Bose innards, you will see a huge transformer weighing 44 lbs! It also has some large caps. The Kenwood Supreme is a Dual Mono Amp, with 2 transformers(1 per channel) and 2 large caps per transformer. I consider the Kenwood Supreme to be the exception.

 

[BilboBaggins]

One other thing.

I would not use a vintage McIntosh such as the MC2205 with any Kef speakers. I did a test once and carried my MC2205 into the basement with the Bose 1801. I then tried it with my Kef 105s and I think the 104/2s. A friend dropped by that afternoon and thought the same as I did. That the Kef sound best with the Bose amp. They still sound good, but they sound so much better with proper power. My 107s have displaced the 105s, and the 1801 drives the 107s beautifully! They are heads and tails better sounding that the 105s. And remember the 105s were pretty close to the 104/2s. I kept the 105s because I didn't need to do the foam tires or the ferrofluid in the tweeters. Otherwise, it was a flip of a coin.

 

[z-adamson]

In my opinion, the “ohms rating” on the speakers means very little.

Look at an impedance graph instead. The graph is something you can actually get useful info from.

 

[Akustic]

Ha! I'll try not to be.

I admit I am a sucker for older equipment. It probably goes back to being a child of the 70s and falling in love with records as a young kid and wanting to one day own a Garrard TT and Pioneer receiver like my parents. No longer am I wishing for that Garrard, but I have owned Pioneer TTs and Receivers in the past and do like some of them.

The best modern gear I have owned was an Arkam amp and it was fantastic. Far better than a Cambridge Audio I once owned. But, I still prefer both the Luxman R-1050 and the Onkyo TX6500 over both (sonicly and aesthetically).

Serious question for ya....the KEFs were made in the mid-80s....they would have been made with both 70s and 80s high end gear in mind. Why do you think a late 70s quality receiver/amp such as the Luxman and Onkyo is good, but not great when paired with these speakers? I'm not technical, but I have read these speakers do indeed sing with more power such as a 100 or even 200w, but I tend to go with what my ears like and I am also a sucker for aesthetics and a lot of older hifi equipment appeals to both my ears and eyes.

PS: the bass and midrange on these KEF 104/2s is out of this world!

All amps sound different one from another ..
The KEF's are one of the most neutral speakers available ..they expose the amp's sonics ..
It isn't related to the age or "vintage" of the amp ..only it's quality.
The 104's are not an easy or common load for an amp ..
As Rick and Bilbo have noted, they need and deserve a serious power amplifier to achieve what they're capable of ..

The 104's are Classics for a reason.. owned and praised as right, by the musician's who create the music.
They're one of the most capable speakers available ..
They will only truly make music with a power amp of equal quality driving them ..

 

[Mart Mccall]

great speakers but as said above I don't think either of your vintage receivers will get the best from them.

Suspect the Onkyo sounds 'bright' because it cannot drive the speaker sufficiently in the bass. The Lux should be better but still not ideal.

KEF designed the speaker to present a constant 4 ohm impedance load but it still dips down to 3.4 ohm. Therefore I'd recommend an amplifier that gets close to doubling its power output into a 4 ohm load (compared to 8 ohm). You don't need a lot of watts as it is a very sensitive speaker (unless you have large room and like high levels, that is).

 

[Buanadha]

You, my friend, are exactly what I needed and you are spot on! I didn't see that note as I disconnected my old speakers and wired up the KEFs at the speaker end rather than at the receiver's end and therefore didn't see the sticker. Thanks!

I know it is always a matter of preference, but I am curious to hear others thoughts on which of the two amps/receivers paired with the KEFs? I love the warmth of the Luxman and coupled with the warmth of a pair of British made KEFs it has me in its grip, which I guess answers my own question as it is me who is playing it. However, the Onkyo is a killer amp too, but it is definitely much "brighter", which isn't bad...just different.

...

great speakers but as said above I don't think either of your vintage receivers will get the best from them.

Suspect the Onkyo sounds 'bright' because it cannot drive the speaker sufficiently in the bass. The Lux should be better but still not ideal.

KEF designed the speaker to present a constant 4 ohm impedance load but it still dips down to 3.4 ohm. Therefore I'd recommend an amplifier that gets close to doubling its power output into a 4 ohm load (compared to 8 ohm). You don't need a lot of watts as it is a very sensitive speaker (unless you have large room and like high levels, that is).

Really LOVE the KEF speakers from that era -- For my KEF 103/4's, I want something that will bring out the details on the highs and provide pop for the clear, concise bass of the KEFs, but keep/not lose the sweet, wonderful mids/vocals that the KEFs bring and I would think the Luxman would be closest to that - so I think with your options, the Luxman likely pairs best with your KEFs.

But I also think that Luxman may not provide as much power as you might like/need with them (oddly, the US flyer for that amp only says 55 watts into 8 ohms, but the German version seems to show 90 watts into 4 ohms (says "Ausgangsleistung" which I think refers to clipping in that context)

https://www.hifiengine.com/manual_library/luxman/r-1050.shtml

Most amps won't really double as they go from 8 to 4 ohms, but within practical limits that looks like an amp that won't have issues with 4 ohm speakers at all, and probably provides more power than indicated (much like the NAD amps I use with my KEF 103/4's).

IIRC, some of the 104/2's have 2 sets of connectors and are bi-ampable. Not sure if yours are, but that may open up some other options. I've like the results with my KEF 103/4's by doing a vertical, passive bi-amp (using 2 identical amps, one for each speaker), but others like using a different amps for the highs vs. the lows - so that may be an option and may be a way for you to use the Luxman for the highs while paired with something more powerful for the lows.

If I were you, I'd probably use the Luxman for now, but look for some options to upgrade over time. I like the late 70s to early 90's era a lot for amplifiers (so many great designs/builds from then) and very good percentage of those amps were built to drive 4 ohm speakers, so there are a lot of options that won't fall apart with those speakers and you certainly can't go wrong with any of the great Luxmans of the past (outside of hitting the wallet!)

 

[the skipper]

All good advice but I'd like to add one caution: Never run a four ohm speaker in parallel with any other speaker.

 

[MKF]

Some great replies here and I thank you all for sharing your two cents. You have given me much food for thought. I was fortunate to have stumbled on both my Onkyo and Luxman and I traded other receivers for them. I straight up traded a Cambridge Audio 640A for the Onkyo TX6500. The Onkyo had been restored and the guy was having trouble shifting it due to its size and weight. He knew he could sell the Cambridge quicker and still make a buck so we traded. I still firmly believe I got the better end of that deal, but it was a win/win for both, I suppose.

I traded a Pioneer sx-737 for the Luxman, but had to drop a bit of cash on top for that deal. Again, very happy to have walked away with the Luxman. The dude who made that trade said it was good for him as although the Luxman is a better receiver, the Pioneer name is better known to the "masses" than Luxman, which made it easier for him to shift. But, he also knew the Luxman just needed the right person, which I guess was me.

KEF Concerto's were mentioned, which once upon a time ago I had a pair, (Concerto 1), but I gave them to my son. I think those speakers made a real impression on me as I drove them with an Arkam amp and the sound was so warm that it made me fall in love with British stereo equipment. I always sang KEFs praise after that.

I was in the right place when I came across the 104/2s and couldn't resist. I have now replaced a pair of Sansui 8000x speakers with them (you all are no doubt thinking, man those KEFs are in a different league, which I agree and is why I jumped on them). I thought, and still think, the Sansui's were/are solid, but as many know the large bass cone squeezed into that cabinet doesn't help that speaker so when I powered up the KEFs the bass and midrange, in particular, immediately grabbed me. However, last night I was listening to Billy Cobham's 'Spectrum' album and the drums on 'Stratus', especially the higher end drums and cymbals and Cobham's stick rolls on the edge of the drums, was such a blatant difference on the KEFs that it made the LP truly spring to life. Almost like rediscovering the album and its many sounds and hearing it again for the first time. Definitely time to shift the Sansui's and let somebody else enjoy them because these KEFs are staying put!

I will keep all the amp/power amp discussions in mind and if the right bit of equipment shows up I may one day part with the Luxman, but for now I really do love that baby and will let it do its thing with these KEFs.

I also appreciate The Skipper's point of not running other speakers parallel. Thanks!

Before I leave I do have a couple questions:

(oddly, the US flyer for that amp only says 55 watts into 8 ohms, but the German version seems to show 90 watts into 4 ohms (says "Ausgangsleistung" which I think refers to clipping in that context)

This is odd and very curious and makes me want to investigate further!

AND:

Look at an impedance graph instead. The graph is something you can actually get useful info from.

I am not an audio engineer and I feel stupid to say I am not sure how to properly read the graphs. I have seen the impedance graph for the KEFs, but again I am not entirely sure how to interpret it. Can you help enlighten this common dude? Much appreciated.

Cheers again, all!

 

[z-adamson]

To check an amps ability to run a 4ohm load, look at power output at 8ohms. Look at power output at 4ohms. If the power output at 8ohms is HALF of the power output at 4ohms, good to go. To be clear…20-20k hz, 0.01%thd. Not some other bogus power rating.

Not much home hifi gear is spec’d this way. Some is though.

The problem here is that a lot of cost gets added in as you double the amps output at 4ohms. Output transistors, more heat sink material etc. etc. And so, manufacturers cut the cost and simultaneously cut the amps ability to run 4ohms. The things that need to be done to an amp to make it efficiently run 4ohms are the very things that cost manufacturers a lot of money and that gets passed to the buyer. So for obvious reasons, not many home audio amps are built this way.

 

[z-adamson]

I am not an audio engineer and I feel stupid to say I am not sure how to properly read the graphs. I have seen the impedance graph for the KEFs, but again I am not entirely sure how to interpret it. Can you help enlighten this common dude? Much appreciated.

Cheers again, all!

Post the graph…

 

[z-adamson]

And I would agree….your amps will not cut it assuming these are a true 4ohm load. And assuming you want to get the most out of those speakers.

You will need something along the lines of a Levinson 5302 stereo amplifier. It actually says on the specs “power doubles to 270wpc into 4ohms”. This amp is made to be used with difficult loads. Works just as well with easy to drive loads as difficult loads. If you don’t end up using this amp in particular, you will want an amp like it.

Another option…pro audio.

 

[justjed2]

I'd look for a vintage 125wpc@8 ohms class AB MOSFET amp. Pro amps are good solid performers, often with as good, if not better, specs than similar home audio pieces. My example of this is a Soundcraftsmen A2502. Mine is more than 40 years old, and had been butchered internally by a previous owner. It was rebuilt by MTX, who had the service contract for Soundcraftsmen at the time, and later had a complete re-cap by a trusted local technician. It works the crap out of a pair of 6 ohm, 86dB@1W/1M speakers, at serious volume levels(big room/ small speakers), and without getting more than mildly warm. Any of the big home audio names from the 70s-90s should be more than up to the task, Pioneer, Kenwood, Technics, etc. Even one of the Sony ES series amps would do the job you're asking quite nicely.

Amps should be the easiest component to get right, in my opinion. You just want to amplify the signal, not add anything to it. And yet they all sound just a little bit different from one another. I think MOST of this has to do with the power supplies, however.