• 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!

More power for KEF reference 5?

frmir

New Member
Joined
Jun 6, 2023
Messages
4
Likes
0
Hi,
I recently jumped on the opportunity to buy a pair of KEF reference 5 second hand at a good discount. Specs recommend an amplifier between 50W and 400W (cf specs). I already had a Mark Levinson 5805, rated at 125W under 8 ohms and almost double under 4 ohms (cf meas). The system is setup in a room measuring (WxDxH) 20x21x22, open at the back and cathedral ceiling. Often with classical music records, I turn the volume knob higher, let's say up to 50 or even 60 over 80 which is the max. I was wondering if I was under exploiting the potential of the KEF and needed a more powerful amplifier. KEF is also recommending using an amplifier providing 60% to 110% of the speakers max amp rating (cf kef blog). So I was thinking about using the Mark Levinson as a pre-amp and adding a class D power amplifier like the NCx500. But given your experience and your expertise, will it make such a big difference in terms of sound quality? Is my amplifier sometime clipping without me noticing and slowly but ultimately, it's destroying my speakers? I don't have access to a class D amp "just to try", so what's why I'm looking for your opinion.
 

Matias

Master Contributor
Forum Donor
Joined
Jan 1, 2019
Messages
5,152
Likes
11,113
Location
São Paulo, Brazil
Most manufacturers have a return policy, maybe some restocking fee, plus shipping back. Still it's a small risk to test one in your system and know for sure. Just contact them and explain in advance so there are no misunderstandings imo.
 

Ciobi69

Senior Member
Joined
Jan 27, 2022
Messages
463
Likes
289
If I could ask how much did you pay? I would like the reference 5 or blade 1/2 used, i have parasound jc1 I think they could be perfect
 
OP
F

frmir

New Member
Joined
Jun 6, 2023
Messages
4
Likes
0
A third of the original price for a 2 years old product, or so I have been told.
 

wgb113

Active Member
Joined
Feb 25, 2019
Messages
145
Likes
151
Location
Pennsylvania
Ok around 5-6000?
That’s a killer deal If that’s the case!

I’m pushing 300W through my Reference 3 in a much smaller room. I can’t imagine that you’re clipping with your Levinson but if you’re running them full range (without subs) at high volume levels more power can be better.
 
OP
F

frmir

New Member
Joined
Jun 6, 2023
Messages
4
Likes
0
I’m not well aware of the various fault mechanisms of speakers due to underpowered amplifiers. A quick search in the publications of the aes society gives me this article: “An Investigation into How Amplifier Clipping is Said to Burn-Out Loudspeakers, and How Limiters Can Save Them” [1] but it’s behind a paywall. Otherwise, there is this short notice: [2] on top of kef recommendation. Thanks for your advices folks. I will plug a more powerful amplifier.
 

soerenssen

Addicted to Fun and Learning
Joined
Jul 25, 2023
Messages
558
Likes
125

For the Reference 3, he recommends even the NC1200, but class D amps sound "clinical" for him, whatever that means. It sounded best with the AHB2, although less power.
I have the Reference 3 Metas now and I'm looking for the perfect amp match, heavily considering two NCx500 monoblocks. But I was wondering if two LA90D would sound nicer. Based on the above review it matters a lot if it's class A or class D, but I cannot compare them, so I'm trying to rely on other people's advice. The Ref 3 has 86dB sensitivity and requires a bit less power (300W) than the Ref 5. If it'd be clipping all the time with the AHB2 and the mono LA90D, I am maybe better off with the NCx500.

Edit: On the same site I found a Kef Ref 3 + LA90 (non-discrete) review too: https://soundnews.net/amplifiers/power-amps/topping-la90-review-block-rockin-beats/
 
Last edited:

soerenssen

Addicted to Fun and Learning
Joined
Jul 25, 2023
Messages
558
Likes
125
I contacted KEF to ask for amp recommendations for the Reference 3 Meta and this is what they told me:
- they don´t have experience with NCx500 amps but they do have concerns about using Class D amps in this performance class - the Class D amps that they know sound a bit "cold and harsh"
- their recommendation was the Hegel 390 or 590 integrated amp
- ultimately, one should listen first and buy after listening

I haven't tested the speakers with the NCx500 yet, but I'm now considering opamps like Sparkos / Sonic Imagery - although @amirm 's review is putting me off a bit:
 

quattro98

Active Member
Forum Donor
Joined
Jun 14, 2018
Messages
177
Likes
179
Location
Chicago, IL
I would have no hesitation with class D or any other topology of well designed amplifier. I would not buy an amplifier based on subjective reviews of the character of the sound. What matters most is adequate power to drive the speaker to your listening levels in your room at your seating distance. One option is to get an amplifier based on the objective information on ASR (or Audioholics or other resources) and make sure you have a return period. A good amplifier should work with whatever speakers you choose. In the specs from the OP, the sensitivity is 90dB/2.83V/m, so unless you listen super loud or in a very large room, I doubt he/she needs more power.

I also have the Reference 3 Meta. I am currently in the middle of a system change after a move. Right now, they are in a 5.2 system (eventually back to the 7.2.4 that we had before moving). I am using a Denon 8500 and it works fine at my listening levels (moderate, not loud) and distance. I also mostly use the subwoofers, so the high pass for the speakers cuts down the power required. My own future choices will likely be a Denon A1H receiver vs Marantz processor with separate amp (either Marantz multichannel or Buckeye).
 
Last edited:

soerenssen

Addicted to Fun and Learning
Joined
Jul 25, 2023
Messages
558
Likes
125
I would have no hesitation with class D or any other topology of well designed amplifier. I would not buy an amplifier based on subjective reviews of the character of the sound. What matters most is adequate power to drive the speaker to your listening levels in your room at your seating distance. On option is to get an amplifier based on the objective information on ASR (or Audioholics or other resources) and make sure you have a return period. A good amplifier should work with whatever speakers you choose. In the specs from the OP, the sensitivity is 90dB/2.83V/m, so unless you listen super loud or in a very loud room, I doubt he/she needs more power.

I also have the Reference 3 Meta. I am currently in the middle of a system change after a move. Right now, they are in a 5.2 system (eventually back to the 7.2.4 that we had before moving). I am using a Denon 8500 and it works fine at my listening levels (moderate, not loud) and distance. I also mostly use the subwoofers, so the high pass for the speakers cuts down the power required. My own future choices will likely be a Denon A1H receiver vs Marantz processor with separate amp (either Marantz multichannel or Buckeye).
I'll go with the NCx500 for sure, probably a dual mono configuration for enough power reserve if required. I want to avoid extra stress on the power supply, clipping and any crosstalk if possible. I will run the KEFs without subs initially.
 

BrokenEnglishGuy

Major Contributor
Joined
Jul 19, 2020
Messages
2,066
Likes
1,232
My recommendation is buy purifis mono, and you done
When i asked to kef support years ago about running my r7s, i shared the measurements from here about the purifi eigentakt eval1, they didnt like the fact of this site havikg some little measurements and have no much recommendation for this eigankt, apparently they still have no idea about class D, yet they made the ls60 or hegel give some nice money for recommend his amps
In short history purifi was the best election so far, purifi>any hegel.
————————-
Edit: i found the email, apparently i was not asking for the R7, instead i was asking why the r300 was making weird woofer noises at high listening volumes, it was the little bookshelf because now i have the r7 and can play hell of a much higher listening volume than my r300
This was his answer from 2021:



I'm not convinced that this type of amplifier is good enough to drive the constant load of the R300. The speaker will increase in load as the demand becomes greater, so what you are hearing is distortion where the amp cannot deliver adequate current to the speakers as they require it.

I read that this amp is to be used as a test-bench amp in lab conditions. Though I'm not overly familiar with this (as it is so obscure), and they do not list the power output (current) or RMS figures, I cannot suggest what you need to improve this.

To run a continuous load at high listening levels, you need good current which is supported by the power supply, so I think this is your limitation.
------------
EDIT2: to be fair with kef support, the purifi eigentakt was a really new amp in 2021, its design is really new
 
Last edited:

soerenssen

Addicted to Fun and Learning
Joined
Jul 25, 2023
Messages
558
Likes
125
My recommendation is buy purifis mono, and you done
When i asked to kef support years ago about running my r7s, i shared the measurements from here about the purifi eigentakt eval1, they didnt like the fact of this site havikg some little measurements and have no much recommendation for this eigankt, apparently they still have no idea about class D, yet they made the ls60 or hegel give some nice money for recommend his amps
In short history purifi was the best election so far, purifi>any hegel.
————————-
Edit: i found the email, apparently i was not asking for the R7, instead i was asking why the r300 was making weird woofer noises at high listening volumes, it was the little bookshelf because now i have the r7 and can play hell of a much higher listening volume than my r300
This was his answer from 2021:



I'm not convinced that this type of amplifier is good enough to drive the constant load of the R300. The speaker will increase in load as the demand becomes greater, so what you are hearing is distortion where the amp cannot deliver adequate current to the speakers as they require it.

I read that this amp is to be used as a test-bench amp in lab conditions. Though I'm not overly familiar with this (as it is so obscure), and they do not list the power output (current) or RMS figures, I cannot suggest what you need to improve this.

To run a continuous load at high listening levels, you need good current which is supported by the power supply, so I think this is your limitation.

With Best
I opted for the NCx500 as opposed to the Purifi for more performance, but with comparable measurements. I really hope that going for a dual mono setup with a dedicated SMPS 1200W (325W continuous) power supply for each NCx500 amp module is a safe bet and it has enough power reserve. I asked Apollon, Audiophonics and Nord, all of them assured me that even the stereo samp with a single PSU would be adequate. But I want to be on the safe side and rather not put too much stress on a single power supply when driving these speakers without subs.
Current would be 28A from the mono blocks, while 27A per channel using a stereo amp (single PSU).
 

BrokenEnglishGuy

Major Contributor
Joined
Jul 19, 2020
Messages
2,066
Likes
1,232
I opted for the NCx500 as opposed to the Purifi for more performance, but with comparable measurements. I really hope that going for a dual mono setup with a dedicated SMPS 1200W (325W continuous) power supply for each NCx500 amp module is a safe bet and it has enough power reserve. I asked Apollon, Audiophonics and Nord, all of them assured me that even the stereo samp with a single PSU would be adequate. But I want to be on the safe side and rather not put too much stress on a single power supply when driving these speakers without subs.
Current would be 28A from the mono blocks, while 27A per channel using a stereo amp (single PSU).
Both objectively are very good, i trusted the objective side and im very happy with my purifi, i have everything i wanted

I bought the Purifi from usa, without listening
 

soerenssen

Addicted to Fun and Learning
Joined
Jul 25, 2023
Messages
558
Likes
125
Both objectively are very good, i trusted the objective side and im very happy with my purifi, i have everything i wanted

I bought the Purifi from usa, without listening
Last year I would've opted for the Purifi without a question, but now that the NCx500 is out, I was considering that and also the 1ET7040.
Above 3.2 ohm they measure similarly so I go with the cheaper one. The mono 1ET400 is now cheaper and would probably be sufficient too, but I don't want to risk it with the KEFs.
 

BrokenEnglishGuy

Major Contributor
Joined
Jul 19, 2020
Messages
2,066
Likes
1,232
Last year I would've opted for the Purifi without a question, but now that the NCx500 is out, I was considering that and also the 1ET7040.
Above 3.2 ohm they measure similarly so I go with the cheaper one. The mono 1ET400 is now cheaper and would probably be sufficient too, but I don't want to risk it with the KEFs.
Having the R7 i also think the 1et400 stereo is enough, in fact i have -12dB in the ApoEQ because of the room correction, and still have plenty of volume for crank the speaker up

But if you can, i would go with mono

I remember my friend got the purifi multichannel from NAD with his reference 3, no problem
 

soerenssen

Addicted to Fun and Learning
Joined
Jul 25, 2023
Messages
558
Likes
125
Having the R7 i also think the 1et400 stereo is enough, in fact i have -12dB in the ApoEQ because of the room correction, and still have plenty of volume for crank the speaker up

But if you can, i would go with mono

I remember my friend got the purifi multichannel from NAD with his reference 3, no problem
Multichannel with dedicated power supplies for each amp or shared power supply?
 

BrokenEnglishGuy

Major Contributor
Joined
Jul 19, 2020
Messages
2,066
Likes
1,232
Multichannel with dedicated power supplies for each amp or shared power supply?
shared power supply
if i remember correctly was this
 
Top Bottom