Considering Purifi vs Hypex MP but don't want to overpower LS50's

[ChrisH-CT]

Hi

I'm narrowing down a purchase of a Class D amp upgrade to drive my KEF LS50 Meta's that I use in a small room and listen 5-6 feet from the speakers most of the time. (But there are occasions where I'm moving about the room and a neighboring room, while letting the music play at a fun volume.)

I currently have an ICE DIY amp that I think is rated for 50wpc. And the times that I turn it up, I feel like the the KEFs are not giving their best. And I want the best fidelity that these speakers can possibly provide, at all volumes.

I want an amp with an internal power supply and I've been looking at Buckeye and VTV. I realize Buckeye focuses on what counts and puts it in a practical shell. But I have to say I am drawn to the looks of the VTV.

Realistically, I probably only need a Hypex NC252 MP as far as power goes. But I've been considering a Purifi-based amp, because of concern for longevity of Hypex MP (as discussed elsewhere on ASR). Plus my wanting the best fidelity possible for my KEFs. (Which are combined with an active subwoofer.)

It seems that the Purifi 6525 is the least expensive Purifi option in pre-built products from the likes of Buckeye and VTV. But I have concern about the power being overkill for my near-field situation. I've reasoned that, As long as I don't go nuts with the volume, it shouldn't be a problem. But I also don't want to end up with my volume control becoming touchy because of all the gain. Because when it's late at night, I need to listen at very low volumes. So I need to keep a wide range of volume detail at lower volume knob positions.

So hopefully I've painted a picture that sufficiently explains my quandary.

 

[BeeKay]

Before the drivers turn to ashes, your ears should naturally cry for a stop. Hard to overpower a loudspeaker when common sense is present.

 

[ChrisH-CT]

Before the drivers turn to ashes, your ears should naturally cry for a stop. Hard to overpower a loudspeaker when common sense is present.

Thanks for the backhanded questioning of my common sense. I'm very aware of what distortion sounds like and when a speaker is in distress. Since escaping my teens, I have never "injured" a speaker. My question still stands for others willing to offer some insight, on the advisability of putting a powerful amp in a near-field listening situation.

 

[Vincentponcet]

You just don't use it at its max power. Tbh that's the common case for most people here, you don't really need 200W of continuous power even in far field.
In your case, you will probably stay at <10W or even below.
In near field the most important parameter is the residual noise, because you are at low power, for purifi, you are at the smallest among most all power amps, at 6uV.
Look at the Sinad graph over power.
You will see the Sinad at low power, and it is still very good.

 

[YSDR]

IMO a good option would be a Hypex Nilai 500, setting the gain to the lowest position. This way If you use a typical DAC for the volume control with 4-5 V max output, you probably don't have to worry about for voice coil burning even if the DAC is at max volume. Plus the Nilai 500 have the longest warranty of all Hypex or Purifi amps with 5 years. Ohh and the only amp from Hypex or Purufi that still have the buffer in the signal path at its lowest gain, which means easier load for the pre-amp/DAC.

 

[MaxwellsEq]

As long as I don't go nuts with the volume, it shouldn't be a problem

That's absolutely correct.

But I also don't want to end up with my volume control becoming touchy because of all the gain

That's something slightly different. Power and gain are not related. In general, more recent amplifiers have less gain than classic 1970s amplifiers, because our sources have higher voltages than a few decades ago. Also quite a lot of power amplifiers allow you to change the gain, so if you set the gain low, you have more safe travel on your volume control.

 

[bluefuzz]

I'm very aware of what distortion sounds like

Well, there is your answer. The only issue in using a 'too powerful' amp is the possibility of turning it up too loud so the speakers distort. If you trust your ears to detect this eventuality then the 'problem' is moot.

I'm very happy with the little Fosi V3 on similar sized speakers. It can play more than loud enough with negligible distortion and costs a fraction of similarly specced Hypex or Purifis.

 

[sq225917]

You're more likely to damage a speaker by listening loud with a low powered amp than a higher powered one, its the clipping of the signal that does the damage.

That said there's plenty of pics on the web where people have over driven their kef speakers, current models, and the cones have cracked/imploded.

As long as you're not hitting the end stops on the driver a higher powered amp is the safer choice.

 

[Gorgonzola]

This is the same practical advice I've given for decades; that is that there is no danger in an amp with far more power than you need. "Need" meaning the power to drive the speakers to the maximum distortion-free level you would ever want to listen to.

 

[Jim Taylor]

... the advisability of putting a powerful amp in a near-field listening situation.

I've used nearfield positioning off and on since 1967, and steadily since 1998. I've used amps rated from 30 wpc to 125 wpc. With one exception, I could not tolerate the SPL provided by any of those amps run wide open.

However ... we need to discuss that "one exception" that I mention. It's bass output. Loudspeakers having limited low-frequency output can be easily damaged by signals with high-level low-frequency content. You've probably seen videos on YouTube of LS50 speakers being [over]driven by the Bassotronics track called Bass, I Love You. I'm not sure why people did this to their speakers, but it is definitely damaging.

The cure for that situation is to use a sub and roll off your LS50 pair with a high-pass filter.

I listen mostly to Baroque, Classical and Romantic-era music ... and mostly symphonic in nature. I've used gentle bass boost on many recordings that sounded "thin" (certain Otto Klemperer recordings come to mind) and have never had any problems.

The members here who have answered your post have all given you good advice. That includes @BeeKay , who, I am certain, did not intend to question your common sense in any way, backhanded or otherwise..

 

[Matias]

You can always get a powerful amp like the Purifi but use it with a very low gain, so that the source (DAC?) will not be able to output enough signal to damage the speakers.

In other words, get the new amp, connect to the DAC, turn the volume way up and use the minimum gain you are comfortable with regarding listening levels (SPL). Then turn the DAC volume down and you are done.

 

[terryforsythe]

I currently have an ICE DIY amp that I think is rated for 50wpc. And the times that I turn it up, I feel like the the KEFs are not giving their best. And I want the best fidelity that these speakers can possibly provide, at all volumes.

I would add a subwoofer before changing the amplifier.

In my experience, when using small bookshelf speakers, adding a subwoofer to fill in the low bass always helps. Also, it will releive some of the load off of your amplifier at the low end.

Good solid state amplfiers should sound transparent, and thus should sound the same. I don't know how good is your ICE DIY amp, but assuming the engineer(s) who designed it is/are competent, you probably will not hear a difference unless playing it very loud.

50W/ch will push a pair of the LS50 Metas to about 102dB at 2m (~6 ft). Leaving 20dB for dynamic headroom, you could listen at 82dB nominal, which is quite loud.

 

[tineared]

Get the Purifi amp and enjoy yourself.
It will be a future proof addition to your music listening that you can always re-purpose
Proper equalization and a subwoofer would probably further increase your enjoyment

 

[Rit]

Get the Purifi amp and enjoy yourself.
It will be a future proof addition to your music listening that you can always re-purpose
Proper equalization and a subwoofer would probably further increase your enjoyment

This is what I did and I am blown away everyday.

 

[SHB]

As an owner of LS50’s, if you want to get the most out of them, get a good sub or two (for stereo), cross them over at 170Hz (at the lowest) and don’t worry about amp power.

This takes all the stress off the LS50’s to create low bass and reduces both THD and IMD. It also increases the dynamic range of your audio system by 10dB or more.

If you like your speakers now, you will love them with a properly dialed in sub. I use four Rythmik Audio L12 servo subs.

As to amps, a pair of Topping B200 monoblocks will be perfect for the KEF’s. The B200’s have more than enough power and will produce no audible noise or distortion driving the LS50’s. The class D amps are great, but the B200 is even better

Once you get the sub(s), install the included foam plugs into the LS50 ports. At that point, they aren’t using the ports for music. All you’re doing is allowing port resonances and other spurious noises to escape from the cabinet into your listening room.

 

[ChrisH-CT]

Thanks for the responses.

I do already have a subwoofer. And I'm going to add a passive High Pass filter to the KEFs.

And regarding the recommendations of amps with external power supplies. I want to stick with internal power supply. I also want to stick with a vendor that is U.S. based (for support).

I believe all of the responses boil down to: Don't worry about pairing a powerful amp with small speakers. That's reassuring, thank you.

 

[Sokel]

cross them over at 170Hz

???
I hope the setup you suggest is having the subs as a base to mains, or tightly close, or else a 170Hz x-over for non- collocated subs with mains is astronomically high.
The 1/4 wavelength rule for x-overs alone is enough.

 

[Rit]

I had the same fear with the Buckeye-purify amp. I’m using the WiiM ultra and it has an output feature that will limit power output, if anything it’s comforting to know that if by accident the volume is raised unexpectedly that no damage will occur. In my mind I feel that running an amplifier at its lower power rating means less distortion. I like what I’m hearing and have no desire to update.

 

[phoenixdogfan]

I have been using the combination of LS 50 Metas and a Purifi Eval 1 Eigentact stereo amp to power them for the last 4 years. I listen at a distance of 1.5 meters in a 12' X 12' x 8' room, and neither the speakers nor my hearing is any the worse for wear. I also cross over to dual SVS SB 2000 subs at 150 hz.

And, yes, they sound superb at all sane volumes.

 

[SHB]

Thanks for the responses.

I do already have a subwoofer. And I'm going to add a passive High Pass filter to the KEFs.

And regarding the recommendations of amps with external power supplies. I want to stick with internal power supply. I also want to stick with a vendor that is U.S. based (for support).

I believe all of the responses boil down to: Don't worry about pairing a powerful amp with small speakers. That's reassuring, thank you.

The passive crossover will work, but a biamped, sub/sat system will give you the best performance. Also, passive crossovers, especially ones that low, waste a ton of amp power.