Need Power amplifier Recomendations 1000.00 or less 500 watt minimum @4ohm.

[svart-hvitt]

A friend recently wrote this on music, amps and power:

https://www.kvalsvoll.com/blog/2018/12/02/how-much-power-do-i-need/

 

[maty]

https://www.doctorproaudio.com/doctor/calculadores_en.htm#calc_spl

Go to SPL calculator. And I do not have to make a capture again and again because I have KEF Q100 5.25" coaxial speakers with true sensitivity of 85 dB/W/m and minimum 4.7 Ohms Really is 84-85 dB/W/m, then the worse scenario is with 84 dB/W/m.

85 dB and 2.4 meters is similar to 84 dB and 2 m

An old capture: KEF-Q100-SPL-84dB-20w-2m-random-94dB.png

I listen to very good recordings, with (very) high DR. And more are orquestral music.

Usually in near field (in phase). When I am excited, at 3m (random phase).

My second system: PC -> ODAC -> AV Marantz SR4500 -> KEF Q100

About 65 dBSPL continuous. I have many tracks with DR17, but a lot of more at DR15.

Then 65 dB continuous + 15 dB peak = 80 dB.

80 dBSPL continuous is loud -> 95 dB (peak).

Off course, better an amp with more watts, if minimum impedance is low. Amp with 80 watts at 8 Ohms at THD 0.1%

Go to SPL calculator. 85 dB, 500 watts, 2 speakers, random phase, 3 m -> 105 dB (peak)!!! -> 90 dBSPL continuous!!!! is very loud in a home room, with WALLS.

 

[maty]

https://www.soundandvision.com/content/marantz-sr4500-av-receiver-ht-labs-measures

[ This graph shows that the SR4500's left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1% distortion at 100.4 watts and 1% distortion at 114.6 watts.

Into 4 ohms, the amplifier reaches 0.1% distortion at 128.2 watts and 1% distortion at 158.8 watts. ]

Your speakers must be nominal 4 Ohms. Mine, < 5 or 6 Ohms (KEF says 8 Ohms nominal).

 

[maty]

The key is that a good class D has a very low output impedance -> speakers (low frequencies) more controlled.

 

[maty]

To finish, A VERY HARD TEST:

Gregorio Paniagua, Atrium Musicae de Madrid - La Folia de la Spagna (2003), SACD, Harmonia mundi, Germany
https://www.audiosciencereview.com/...-are-we-listening-to-right-now.40/post-123680

DR Peak RMS Duration Track
--------------------------------------------------------------------------------
DR19 -8.59 dB -33.84 dB 5:56 01-Fons vitae / Dementia praecox angelorum / Supra solfamirevt
DR17 -7.66 dB -33.72 dB 2:09 02-Extravagans / Laurea minima / In vitro
DR19 -5.67 dB -33.63 dB 2:27 03-Oratio pro-folia / Fama volat / Citrus - Hesperides
DR23 -2.98 dB -33.33 dB 8:12 04-Principalis. Fermescens / Indica exacta / Adverso flumine
DR16 -7.01 dB -32.52 dB 3:11 05-Parsimonia aristocraciae
DR12 -14.82 dB -32.89 dB 1:30 06-Subtilis / De profundis - Extra muros
DR20 -6.34 dB -32.44 dB 1:39 07-Vulgaris - Sine populi notione / Vagula et blandula
DR20 -3.20 dB -30.53 dB 5:06 08-Nordica et desolata / Aurea mediocritas
DR15 -12.51 dB -32.62 dB 2:22 09-Nobilissima / Degradans et corruptae
DR20 -4.79 dB -32.56 dB 5:14 10-De pastoribus / Mathematica dies irae / Crepuscularis / Sine nomine / Tristis est anima mea / Equites fortis armaturae / Audaces fortuna juvat / Sine praeputium / Ecclesiastica
DR17 -3.01 dB -26.07 dB 1:58 11-Theatralis et hipocritae / Ruralis / Alter indica perfecta
DR21 -3.00 dB -28.75 dB 4:34 12-De tolerentia aetherea / Fuga ficta et carrus triumphalis
--------------------------------------------------------------------------------

Number of tracks: 12
Official DR value: DR18

I do not need more power. I want higher SNR (A) at 1 watt and in 10 watts (now is higher than original because it has less noise after my mods). And H2 predominance, adjustable. H2 at 70-75 dB with jazz and small acoustic group and H2 at 85-95 dB with orchestral, electronic and others musics.

https://www.diyaudio.com/forums/headphone-systems/330947-melbourne-class-headphone-amp-pre-amp.html

As you can see, the harmonic profile is always classic SE Class A with 2nd order dominant harmonic and decreasing 3rd order and higher harmonics. With a ratio of -17dB for H3/H2, the sound is very euphonic and the right balance of sweetness and articulation, and the absence of higher orders makes it non-fatiguing to listen to.

https://www.diyaudio.com/forums/hea...-class-headphone-amp-pre-amp-post5626241.html

 

[DonH56]

I guess I don't understand why you say my numbers are wrong. Using the calculator you referenced I do get a slightly different answer, by less than 1 dB (107.3 dB versus my rough calculation of 108 dB). Awfully loud either way. I am not disputing that it is very loud, but I cannot understand why you said I am wrong and asked for my speaker sensitivity and listening distance? The only number I used was 108 dB peaks for 500 W and your online reference agrees reasonably well with my calculations. Are you saying my math is wrong, or that I am wrong for saying the need may exist for such high-wattage amplifiers?

For many years I have used the old IHF/AES studies showing music has a peak-to-average ratio of about 17 dB. That is more for classical, jazz, and some drums in my experience. Movies often exhibit much higher factors, in the 20 dB to 30 dB range from what I have read. I normally listen with the knob set at -33 dB relative to Dolby reference (105 dB) or about 72 dB but I am sure the average level is below that.

My amplifiers are rated at 500 W/ch into 4 ohms with <0.1% THD from 20 Hz to 20 kHz. They are class AB. Class D often exhibits lower output impedance at low frequencies but depending upon implementation may rise faster with frequency than class AB amplifiers because, in addition to changes in feedback architecture, class D must have an output filter that usually includes a large inductor and that decreases the feedback factor and increases the output impedance at high frequency. Modern class D designs have largely obviated that problem with higher switching rates and improved feedback schemes (like a combination of multiloop and feedforward correction).

At any rate it is clear I am not helping, and cannot provide the expertise you seek, or you don't believe mine is of value. I hope you find what you are looking for.

 

[maty]

Well, you are wrong if you think you really need 500 watts at 4 Ohms. In a closed room, with WALLS with little distance between them.

You really want/like the very low output impedance of class D.

Class D, A or AB, in the real world you only need < 10 watts continuous with normal speakers. More watts if you listen music with (very) high DR like me.

Modern commercial music usually has < DR10. A lot of themes with DR5 or DR6.

And the SPL calculations are in a free space, without WALLS.

 

[maty]

A very new Spanish recorder.

Vanesa Martin - Todas Las Mujeres Que Habitan En mi (2018)

DR Peak RMS Duration Track
--------------------------------------------------------------------------------
DR8 0.00 dB -10.34 dB 3:48 01-De tus ojos
DR6 0.00 dB -8.33 dB 3:37 02-Inventas
DR5 0.00 dB -7.34 dB 3:50 03-Abril
DR6 0.00 dB -7.92 dB 3:41 04-Pídeme (feat. Mariza)
DR6 0.00 dB -8.71 dB 3:20 05-El intento
DR8 0.00 dB -10.91 dB 3:34 06-La culpa
DR5 0.00 dB -7.77 dB 4:27 07-En el aire (feat. Abel Pintos)
DR6 0.00 dB -7.85 dB 4:53 08-La vez primera
DR5 0.00 dB -7.43 dB 3:38 09-Desobedecerme (feat. Kany García)
DR7 0.00 dB -9.74 dB 4:34 10-Como un billete de avión
DR6 0.00 dB -9.08 dB 4:01 11-Al mismo tiempo
DR8 0.00 dB -13.03 dB 5:34 12-Que no
DR6 0.00 dB -9.97 dB 4:37 13-Me equivoqué
DR6 0.00 dB -8.06 dB 3:41 14-Pídeme
DR5 0.00 dB -8.23 dB 4:27 15-En el aire
DR5 0.00 dB -7.57 dB 3:38 16-Desobedecerme
--------------------------------------------------------------------------------

Number of tracks: 16
Official DR value: DR6

 

[maty]

To finish -too late here, Tarragona (Spain), some hours ago I posted in a very audiophile forum:

Re: Can anyone suggest a way to find older copies of cds w/ dynamic range?

https://www.audiocircle.com/index.php?topic=160554.msg1717992#msg1717992

The Cars - Shake It Up (1981), CD, Elektra, Germany

DR Peak RMS Duration Track
--------------------------------------------------------------------------------
DR12 -1.52 dB -15.79 dB 3:31 01-Since You're Gone
DR12 -1.87 dB -16.04 dB 3:32 02-Shake It Up
DR12 -2.35 dB -16.81 dB 4:10 03-I'm Not the One
DR13 -3.09 dB -18.62 dB 4:25 04-Victim of Love
DR15 -1.82 dB -17.65 dB 4:57 05-Cruiser
DR14 -1.91 dB -18.58 dB 5:40 06-A Dream Away
DR13 -2.36 dB -18.42 dB 4:27 07-This Could Be Love
DR12 -2.04 dB -16.59 dB 4:56 08-Think It Over
DR13 -1.60 dB -17.69 dB 5:03 09-Maybe Baby
--------------------------------------------------------------------------------

Number of tracks: 9
Official DR value: DR13


The Cars - Shake It Up (1981) CD, Rhino, Expanded Edition 2018

DR Peak RMS Duration Track
--------------------------------------------------------------------------------
DR8 -0.16 dB -10.23 dB 3:31 01-Since You're Gone (Remastered)
DR7 -0.16 dB -9.40 dB 3:32 02-Shake It Up (Remastered)
DR9 -0.16 dB -10.82 dB 4:10 03-I'm Not The One (Remastered)
DR8 -0.16 dB -10.37 dB 4:24 04-Victim Of Love (Remastered)
DR7 -0.16 dB -8.57 dB 4:57 05-Cruiser (Remastered)
DR10 -0.16 dB -11.87 dB 5:40 06-A Dream Away (Remastered)
DR9 -0.16 dB -10.56 dB 4:27 07-This Could Be Love (Remastered)
DR7 -0.16 dB -8.97 dB 4:56 08-Think It Over (Remastered)
DR6 -0.16 dB -8.33 dB 5:06 09-Maybe Baby (Remastered)
DR9 -0.05 dB -10.58 dB 5:57 10-Since You're Gone (Early Version)
DR9 0.00 dB -10.83 dB 4:10 11-Shake It Up (Demo)
DR11 -0.08 dB -12.78 dB 4:11 12-I'm Not The One (Remix) (Remastered)
DR10 -0.08 dB -10.97 dB 5:00 13-Cruiser (Early Version)
DR10 -0.07 dB -11.31 dB 6:19 14-Take It On The Run (Early Version of A Dream Away)
DR9 0.00 dB -10.31 dB 5:21 15-Coming Up You Again (1981 Version of Coming Up You)
DR9 -0.21 dB -10.65 dB 2:54 16-Little Black Egg (Remastered)
DR9 -0.07 dB -10.35 dB 4:22 17-Midnight Dancer
--------------------------------------------------------------------------------

Number of tracks: 17
Official DR value: DR9

And the people are very satisfied!!!!!!
https://www.amazon.com/Shake-Up-Expanded-Cars/dp/B079J83X4S#customerReviews

They are many more than me, so they must be right, I say.

 

[DonH56]

Well, you are wrong if you think you really need 500 watts at 4 Ohms. In a closed room, with WALLS with little distance between them.

You really want/like the very low output impedance of class D.

Class D, A or AB, in the real world you only need < 10 watts continuous with normal speakers. More watts if you listen music with (very) high DR like me.

Modern commercial music usually has < DR10. A lot of themes with DR5 or DR6.

And the SPL calculations are in a free space, without WALLS.

We'll just have to disagree. I doubt I'll ever hit reference peaks personally but a little headroom is useful and I don't like clipping. And I know folk who listen at much louder levels than I. And yes, my calculations were free space, because as I said my room approximates an anechoic space. I don't listen to a lot of modern commercial music.

 

[maty]

In my first comment I asked if it was to listen to music. For movies you need more power but the reality is that the soundtracks also suffer the damn volume war.

In stereo, few more watts are required in the current cinema. The problem is in multichannel systems. With so many channels the amplifier is incapable, especially with loads of 4 ohms, with what usually takes place the clipping much sooner than what the known manufacturers specify with the exception of Marantz.

Many channels, 4 Ohms speakers and the amplifiers get very hot. That iss when modern class D appears as a solution.

In the latest models from Marantz's highest range (first multi-channel and recently in stereo), Hypex NC500 modules are used together with the well-known Marantz HDAM3 buffer. I uploaded pictures in a Diyaudio thread about NC500 in Marantz.

Speaking of buffers, there is the key. There are companies like PS Audio that destroy the excellent good features of the IcePower 700 modules (old tech, with the known peak at HF, from 2004) that use a buffer that makes it H3 predominant, when the logic is that it is H2 predominant or the absence of harmonics. And, off course, they refused to answer my two emails about it unlike Icepower regarding the phase of the 1200AS (modern tech, without the peak but not perfect).

Of course, as they are expensive and audiophile magazines receive money from the manufacturers, they are silent and they are silent again due to the deficiencies of amplifiers, dacs, loudspeakers ...

Money is what it commands.

And all that without breakfast yet, which is Sunday!

 

[MRC01]

...
Speakers = Revel Salon2
Sensitivity = 84.6 dB/W/m -- I used 85 dB/W/m
Listening distance = about 8 feet
...
This is how I figured it (from memory, so could well be off):

• 500 W = 27 dBW (power gain from amplifier)
• Add 3 dB for a pair of speakers (power doubling from the extra speaker)
• 8' = 2.44 m so subtract 7 dB for distance (6 dB for each doubling in distance)
• Net SPL = 85 + 27 + 3 - 7 = 108 dB at the listening position

That agrees with a couple of online calculators I quickly checked. What part is wrong?

My first reaction was 500 watts per channel sounds too high. Then I looked closer at your numbers: at 85 dB/W/m your speakers are roughly 6 dB less efficient than most others, so they need about 4x more power.

Your calculations are essentially correct. But you overestimate the SPL loss with distance. 6 dB for each doubling only applies when the sound propagates spherically with no reflections. In a listening room, even well-damped, it doesn't drop that quickly. So 500 watts is going to produce over 110 dB SPL at the listener position. That will melt your eardrums! I suspect you really only need about half that power, so anything in the 250 to 400 wpc range should do the job nicely. There are lot of good amps to choose from in that power range.

I use Magnepan 3.6/R which are similar in efficiency and impedance to yours. I've used an Adcom 5800 for over 20 years. You can get this amp, or the similar 5802 model that followed it, on eBay for a few hundred bucks.

PS: when you get to these 400+ wpc power ranges, especially with amps that operate in class A, you begin to approach the limits of what a standard 120 VAC outlet on a 20 amp breaker can provide. 120 VAC * 20 amps * 83% = 2 kW. The Adcom 5800 can draw up to 1800 VA so it's approaching that margin. The big Krells, Brystons, etc. have similar power draws.

 

[DonH56]

My first reaction was 500 watts per channel sounds too high. Then I looked closer at your numbers: at 85 dB/W/m your speakers are roughly 6 dB less efficient than most others, so they need about 4x more power.

Your calculations are essentially correct. But you overestimate the SPL loss with distance. 6 dB for each doubling only applies when the sound propagates spherically with no reflections. In a listening room, even well-damped, it doesn't drop that quickly. So 500 watts is going to produce over 110 dB SPL at the listener position. That will melt your eardrums! I suspect you really only need about half that power, so anything in the 250 to 400 wpc range should do the job nicely. There are lot of good amps to choose from in that power range.

I use Magnepan 3.6/R which are similar in efficiency and impedance to yours. I've used an Adcom 5800 for over 20 years. You can get this amp, or the similar 5802 model that followed it, on eBay for a few hundred bucks.

PS: when you get to these 400+ wpc power ranges, especially with amps that operate in class A, you begin to approach the limits of what a standard 120 VAC outlet on a 20 amp breaker can provide. 120 VAC * 20 amps * 83% = 2 kW. The Adcom 5800 can draw up to 1800 VA so it's approaching that margin. The big Krells, Brystons, etc. have similar power draws.

My room is heavily damped (treated) so is very close to the 6 dB 4-pi/anechoic number from the upper bass/lower midrange on up (yes I measured it). My goal was to handle the 105 dB THX max limits; not that I ever want it to play that loudly, but to ensure I was not clipping peaks when I (or more likely my sons) cranked it up.

My previous speakers (for ~30 years) were Magnepan MG-IIIa. Even lower efficiency, though their dipolar pattern gains you a bit back (usually about 3 dB) since the energy is radiated more directly at the listener rather than off to the sides (once past the anel wavelength boundaries, natch).

I have no plans for a pure class A amp; I have heard and used many of them, but not one of my criteria. A well-designed (and biased) class AB amplifier, or perhaps class D, is fine for me. The best a single-ended class A amp can do is 27% efficiency; most are push-pull so reach 50%. That's still a lot of wasted heat. I do have three 20-A outlets but don't really need the extra heat (weight, etc.)

 

[MRC01]

Most of these big powerful "class A" amps aren't pure single ended. They're symmetric AB with high bias, so they operate in class A up to about 10 watts or so then they are AB up to their rated power. The best of both worlds! They are still power-hogs especially when driving low efficiency speakers.

Where does 27% come from? I thought pure class A ideal efficiency was 25%?

 

[andreasmaaan]

My first reaction was 500 watts per channel sounds too high. Then I looked closer at your numbers: at 85 dB/W/m your speakers are roughly 6 dB less efficient than most others, so they need about 4x more power.

Your calculations are essentially correct. But you overestimate the SPL loss with distance. 6 dB for each doubling only applies when the sound propagates spherically with no reflections. In a listening room, even well-damped, it doesn't drop that quickly. So 500 watts is going to produce over 110 dB SPL at the listener position. That will melt your eardrums! I suspect you really only need about half that power, so anything in the 250 to 400 wpc range should do the job nicely. There are lot of good amps to choose from in that power range.

I use Magnepan 3.6/R which are similar in efficiency and impedance to yours. I've used an Adcom 5800 for over 20 years. You can get this amp, or the similar 5802 model that followed it, on eBay for a few hundred bucks.

PS: when you get to these 400+ wpc power ranges, especially with amps that operate in class A, you begin to approach the limits of what a standard 120 VAC outlet on a 20 amp breaker can provide. 120 VAC * 20 amps * 83% = 2 kW. The Adcom 5800 can draw up to 1800 VA so it's approaching that margin. The big Krells, Brystons, etc. have similar power draws.

85dB is fairly standard for small to medium sized direct-radiating box speakers. Although some medium to large woofers have a sensitivity of 91dB or more, this rating assumes 2pi space (i.e. infinite baffle). Place these woofers in a box and bass sensitivity drops 6dB. Compensate for this by attenuating the mids and highs (a.k.a. baffle step compensation) and you end up with a system with a sensitivity in the mid-80s. Of course IRL many manufacturers (not Revel) fudge this spec and quote the speaker's 2pi sensitivity anyway...

Completely agree with the rest of your post though

 

[MRC01]

Your comment made me take a second look at the efficiency numbers. I'm familiar with needing lots more power than most people due to having Magnepan 3.6/R. Their rating is 86 dB on paper, but on closer look that is voltage sensitivity (@ 500 Hz, 2.83 V), not efficiency. 500 Hz is carried by the midrange panel which has 4.2 Ohm impedance, so by my computations that 86 dB is drawing about 1.9 Watts, which is roughly 83 dB / watt.

Most conventional speakers I've seen quote efficiency numbers around 90 dB, plus or minus. If that's accurate, the OP's Revels are less efficient than usual. Perhaps as you suggest many speaker makers are fudging the numbers, I don't know.

However, for sure my maggies are less efficient than the OP's Revels, and like him, I have a well-damped listening room (giant tube traps, RPG acoustic foam, etc.), and the 5800 drives them clean to at least 105 dB SPL measured at the listener position. So I suspect an honest clean 400 wpc is almost certainly enough for his application.

 

[andreasmaaan]

Your comment made me take a second look at the efficiency numbers. I'm familiar with needing lots more power than most people due to having Magnepan 3.6/R. Their rating is 86 dB on paper, but on closer look that is voltage sensitivity (@ 500 Hz, 2.83 V), not efficiency. 500 Hz is carried by the midrange panel which has 4.2 Ohm impedance, so by my computations that 86 dB is drawing about 1.9 Watts, which is roughly 83 dB / watt.

Most conventional speakers I've seen quote efficiency numbers around 90 dB, plus or minus. If that's accurate, the OP's Revels are less efficient than usual. Perhaps as you suggest many speaker makers are fudging the numbers, I don't know.

However, for sure my maggies are less efficient than the OP's Revels, and like him, I have a well-damped listening room (giant tube traps, RPG acoustic foam, etc.), and the 5800 drives them clean to at least 105 dB SPL measured at the listener position. So I suspect an honest clean 400 wpc is almost certainly enough for his application.

I agree with you about the OP's power requirements.

On the question of whether manufacturers tend to fudge the numbers, JA from Stereophile has usefully kept a record of the measured voltage sensitivities of all the speakers he's measured (which are a lot). The median measured number is 86dB/2.83V. But a greater number of speakers fall below that number than above it, probably putting the average at closer to 85dB. Only a tiny percentage of home audio speakers achieve 90dB or higher.

And keep in mind that this is a voltage sensitivity measurement, which is subject to the conditions you mention in your post (i.e. given that many of the speakers will have had a nominal impedance below 8Ohm, average power sensitivity is likely to be a couple of dB lower).

 

[DonH56]

Leaving aside my credibility and engineering skills (or lack thereof), I should note the OP of this thread has not made another appearance since the very first post as best I can tell. And I have no idea what speakers he has, what room, if/how treated, how far away he sits, etc. I can debate the needs of Maggies or my new Revels until I get bored and go home (pretty much there) but I was not the OP and am not looking to change amps right now (well, always thinking about it, but I have enough power to more than satisfy my needs). This last discussion started when I got questioned on the power levels and such; I answered, we seem to be generally in agreement, hopefully done?

The question of sensitivity over frequency is of interest and one of my pet peeves -- most manufacturers measure at 1 kHz and call it good, which may not help if the impedance dips in half at a low frequency, where we are likely to be putting much more power (like 10x or more) into the speakers.

Small bookshelf speakers tend to have much worse sensitivity than their larger brethren. IME/IMO this is not only because cabinet volume generally helps sensitivity, but also because in their quest to provide deeper bass (at least on paper), they tend to pad the tweeter to better balance the overall frequency response and kill the sensitivity.

FWIWFM etc. - Don

 

[Willem]

See here for some serious measurements of the 2x350 watt Yamaha P3500s, sadly discontinued not so long ago https://www.homecinema-fr.com/forum...mpli-yamaha-p3500s-mise-a-jour-t30056383.html

 

[Sancus]

Class D, A or AB, in the real world you only need < 10 watts continuous with normal speakers. More watts if you listen music with (very) high DR like me.

I have Magnepan 1.7is and playing certain rock tracks quite loudly, my(600W SDS-470C) class D amplifier consumes 175-400W. So, this is clearly not true. Even counting some power supply loss that's at least 10x more power than 10W rms. It's not a super large room either, maybe 6m x 7m, and I guess Magnepans aren't "normal speakers" but the sensitivity of the Revels that are highly recommended on this forum aren't a whole lot better. And I'm only sitting maybe 2.5m away from the speakers.

It's easy to imagine why someone might want even more watts than I have, and I don't get why this creates arguments. If someone says hey I want X watts, just believe them, they know their own room, equipment, and loudness expectations. If they end up with more power than they need, so what? Better to have too much power than too little.