How does the NAIT XS 2 handle 4 ohm speakers?

echobase posted:

However, it’s always said that published specs must be taken with salt. The Supernait 2 is rated at only 80w into 8 ohms and 135w into 4 ohms, and yet, have you SEEN the size of the transformer in the Supernait 2? It’s as big as a Morris Mini tire! If that doesn’t have slam, what does? Some amp manufacturers seem keen on demonstrating an ability to exactly double the power output into 4 ohms, but Naim charmingly doesn't care about this. I will have to go in and listen to the SN2. I hope it will suffice as I like the Naim sound, but going for the separates might be a bridge too far. 

echobase, I agree with your overall logic above and having owned the SN2 for three years I can attest to its speed and slam. It has those in droves, plus excellent speaker command. As an example, I compared the Exposure 3010S2 (110 Wpc at 8-ohms with same rated 400 VA transformer as the SN2). Far better speaker command, especially bass control with the SN2. In fairness, the Exposure is a circa $2.5K (US$) integrated. Point being, specs don't necessarily tell the tale, price may to some degree. Still, with 4-ohm speakers it's safe not to skimp on power.

echobase posted:

I neglected to mention that IMO the Hegel is fatiguing to listen to, and isn’t it interesting how this can change one’s perception of things like soundstage, dynamic range, and, even gain. In my observation, they all collapse. The word ‘nasal’ comes to mind.

Word of caution - the ultimate reason I left the SN2 was its fatigue factor. Difficult to listen to in extended sessions and worked best with superior recordings. Speed and slam on well-mastered music were superb in the short term for me, but on the whole of my catalog and for listening for hours on end it became overbearing.

My results in my room with my speakers to my ears. Hopefully you'll find the SN2 a match with your 160 and it seems a logical demo choice. Just be sure to listen to a wide variety of recording qualities at various volumes, and give it an extended trial before deciding. Cheers!

echobase posted:

GIGANTOR- What does your spreadsheet say for listening at 94-100db?

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Echobase

If these are 'weighted' average levels then they are damaging volume levels.

The exposure limit for 94dB is 1 hour, for 100dB it's 15 minutes.

If your listen sessions are longer than this, you may well be damaging your hearing.

Hello Huge,

The head room is what is required for the amplifier.  I am sorry for the confusion.

As an example in my case.

Speaker dB SPL = 84 dB

Distance from speakers = 2 metres

Desired sound SPL at listening distance is 84 dBSPL

For listening to rock with 14 DB headroom for he ampler I would require an amplifier rated at 40 Watts per channel.

For 20 dB headroom for classical one would require an amplifier of 400 Watts per channel

I have another spreadsheet with is a little more complicated and it expresses the following:

For 20 dB headroom at 84dBSPL, the amplifier would need to be at least 100 watts per channel

For 14 dB for rock the amplifier would need to be at least 40 watts per channel.

I hope this clarifies things.

I need the above details from echobase to help determine the amplifier power rating.

I hope this makes sense.

Kind regards,

Paul.

Hi Paul,

Posts crossed over so I deleted the last one!

So are you talking about calculating the power required from the mean (i.e. 'average') SPL?

Wouldn't it be better to select 'fast response' on the sound pressure meter and calculate the (used or required) amp power output from that?
I'm still struggling to understand from what the 14dB to 20dB headroom requirement is derived and why the amp or speakers should care about the musical genre.

(I do understand the technical calculation - that's not a problem at all, in the past I've done some work as electronic engineer.)

OK, I will do my best as I understand it.  These are not my spreadsheets.  These I have down loaded off the internet.  I do not recall where.  Though it is what I have.  The second spreadsheet does have a cell for peak power.

In my case 12 dB head room for Rock/Pop, the spreadsheets recommendation.  For a peak of 84 dB SPL in my case the amplifier would need to be in the range of one watt.

For 20 dB for classical the power required would be also one watt according to the spreadsheet.  I am even confused by this.  One would a expect 6dB increase would require a 4 times in power requirement.  The only thing that appears to change is the average power SPL at specified head room.

Now back to head room.  I interpret this to mean that since rock and pop has less dynamic range.  Possibly due to compressing at mixing.  The transients are less.

I also interpret that classical music has more valleys and highs, hence is recorded  with quiet passages and more dramatic passages one would require an amplifier to be able to reproduce these transients better and allow for them.  Hence recommended by the spread sheet to allow for a 20dB, 100 fold gain in power.

I do notice on the spread sheet it also has a cell for dBW.  Though I believe I will still require echo base's speaker specs/efficiency.

If you wish to supply me with your email addresses?  I am happy to forward the spreadsheets onto both of you or anybody else.

Kind regards,

Paul.

Dear Echobase,

If I use my speakers as an example, 84 dB SPL.  To achieve 100 dB SPL average would require an ampler (including the 14 dB head room for rock) with the power capacity of 1,000 watts rms per channel.  Though this can be obviously reduced if you have more efficient speakers than mine and would believe that should be the case.  For simplicities sake.  If your speaker had the following efficiencies:

87 dB SPL = 500 watts

90 db SPL = 250 watts.

I think you get my picture.  For every 3 dB gain of efficiency the require power will be halved.

I hope this makes sense.

Kind regards,

Paul.

echobase posted:

I have a pair of Dynaudio Focus 160s (4 ohm/ 85db) paired with a Hegel H160 amp. I really like to listen to loud guitar rock with heavy drums and feel sometimes that the Hegel is too polite for these speakers (no slam and no PRaT) and that things get a bit on the thin side when I want to listen loud, although I've never ventured into the realm of distortion, much less, clipping.  These little boxes really demand a lot. I'd like to know if the NAIT XS 2 would do a better job with my speakers for my style of listening or would I really need a Supernait 2 to get real headroom. Thanks.

-Brian

Hi, I read the posts above, and I think the key point has yet to be mentioned... although your speakers are stated as 4 ohm impedance... almost certainly that is a broad average or an impedance at a specific frequency. The actual impedance of the speakers will vary with frequency and some times quite markedly... and so you will really need to see the impedance curve of your speakers which might range say  from 3 ohms to 12 ohms.

So ultimately.. one needs try the speakers themselves on the amp and ensure there are hot spots or shadows in the frequency response like a weak bass, too prominent a mid etc.. other than that there is very little you can do in a paper evaluation. Speaker/crossover to amp to room coupling is rather involved..

however ultimately if it’s volume you after then I’d really recommend more power and amp regulation (addresses those impedance curves) ... and with Naim that starts at the 250.

Having designed an audio power amp, I think I understand the reality better than a spreadsheet dependent on using 'magic numbers'.

Unfortunately, that calculation is actually such massively rough approximation to reality as to make it very unreliable and effectively just computed guesswork.

It also depends on a measurement that few people have the capability of making.  The cheapest way is to play back both music and specifically designed test tracks on the system under test, record them using a calibrated instrumentation microphone and then analyse the recordings using a computer.

Further to that Simon, as you know (and for others here) the effect of phase angle of the speakers can place demands on the amplifier from the components in the imaginary plane.  These demands still have to be met by the power supply and output structures of the amplifier and because of this they reduce the power available in the real plane, this in turn reduces the effect power available that can actually be turned into sound.

G'day Huge, I have ever only used the spreadsheet as a guide that I purchased the correct amplifier.  14 and 20 dB may be, probably are too high and possibly totally inaccurate.  Again I just use it as guide with SPL App on my iPhone.  With owning such inefficient speakers to start with.  I rarely go above 9'oclock on the volume dial.  If my wife is out of the home I may go to 10 o'clock. In fact we have only recently moved to our new home and I have only in the last three weeks connected up the stereo.  Since then I have only turned the amplifier on.  I do no recall playing a disk as my wife likes Netflix so much and the V and HIFI are both in the same room.

An audio engineer I am not.  Though a Radio and Calibration Tech (RAAF) I am and I understand the use of CIVIL and complex impedances, +/- j factors and etcetera.

Warm regards,

Paul.

P.S.  Who is Simon please?

Dear Brian,

log(150)(watts into 8 ohms) * 10 = 21.76dBW

log(250)(watts into 4 ohms) * 10 - 3 = 20.98dBW

21.76dBW - 20.98dBW = .78db => less than 1dB!

I have had another look at the second spreadsheet which I did not understand it too well.  I think I have a grip on it now.

The dBW levels you have supplied for 8 ohms, being 21.76 dBW according to the spread sheet if you use my inefficient speakers as a guide.  With a 150 Watt amplifier it would produce the average SPL of  91.8 dB SPL with a peak dBA of a 105.8 dBA.  It also has a disclaimer if there is a difficult impedance match you may require two to three times the required power for the amplifier.  I am sorry for missing that part out.  My speakers are only rated to 120 watts by the way.

I hope this helps your situation.

Kind regards,

Paul.

P.S.  All in accuracies are those of the spreadsheet writer and not this end user : )

Gigantor posted:

 

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P.S.  Who is Simon please?

Simon is 'Simon-in-Suffolk', one our leading techie gurus on the forum.

This is for the 140, also quoted as 4Ω, I couldn't find one for the 160

It will be down to trying a Nait XS with the speakers but if the 160 follows a similar curve the XS is in with a chance.

The fatigue factor is why I was suggesting trying the 202/200 as an alternative to the supernait, there's a reason for Naim separates.

The Focus 160s have a minimum ohm rating of 4.3 ohms and rise in a linear fashion. They’re not as demanding as many people think. 

Take the Focal 936 which Focal claims a min impedance of 2.8 ohm, the Focal will be more difficult then the 160s to power with wide impedance swings.

The graph for the 140 has a point around 120Hz that's about 4.5Ω and has about -30° phase shift; that makes it quite a difficult load.