Crown 4|300N Amplifier Review

[Deleted member 48726]

You need a lot of power for peaks.
It depends a lot of what music you listen to. Is it EDM or is it "girl & guitar".. -Crest factor plays a role.
Have you got full range speakers capable of low bass and have you applied DSP or room correction.
It is obviously not a "red herring" if the amplifier is going to supply a 9 dB boost from 20 - 80 Hz or if it's not.


From the link in my signature reg. CF-->

Let's imagine an 8ohm speaker with a sensitivity of 90dB/1m.
We want an average sound level at 1m of 94.5 dB SPL (which corresponds to a listening level of approximately 85dB SPL at 3m.)

Calculation of the average power necessary to reach this sound level: Pm = 10^((94.5-90)/10) = 2.8Wrms.
As Pm = Ueff^2/Z, we deduce that in 8 ohms, 2.8Wrms corresponds to Ueff = 4.8Vrms.

This is where CF comes in.

For the same effective value of 4.8Vrms, ie identical average power of 2.8W into 8 ohms, depending on the CF of the signal, we will have very different peak values:

CF 3 => Upeak = 4.8 * 1.41 = 6.8 Vp
CF 6 => Upeak = 4.8 * 2 = 9.6 Vp
CF 9 => Upeak = 4.8 * 2.83 = 13.6 Vp
CF 12 => Upeak = 4.8 * 4 = 19.2 Vp
CF 15 => Upeak = 4.8 * 5.64 = 27 Vp
CF 20 => Upeak = 4.8 * 10 = 48 Vp

A sine wave has a CF of 3.
Good music recordings have a CF of 12 to 15.
The CF can drop below 9 for ultra-compressed music. (see complements and loudness war).
On certain films, the CF can go up to 20.

Amp sizing for this example.​

On the technical sheet of an amp, it is the average power (of ten marked Wrms) with sinusoidal signal which is indicated. It is given for one or more impedances: often in 8, 6 or 4 ohms. We must work with this information to deduce the rest.

We could naively say that for a requirement of 2.8W, we will take some margin and choose an amp given for 5W in 8ohms. Almost double, it should be fine!
But an amp given for 5W in 8ohms means that it is 5W for a sinusoidal signal. This means that it can deliver an effective voltage of 6.3Vrms on sinusoid. So peaks of 9V.
This amp will not be able to correctly pass a musical signal with CF of 6 or more at 2.8Wrms average because the peaks of this signal exceed 9V.

To be able to reproduce a musical signal without clipping with CF=15 at an average power of 2.8W, you must be able to pass peaks at 27V.
On a sinusoid, a peak at 27V corresponds to an effective value of 19V.
So you need an amp with a power announced by the manufacturer of 45W into 8 ohm.

Um... a 45W amp when the average power to reproduce is only 2.8W?
yes because the power announced by the manufacturers is on a sinusoidal signal (normally measured at 1kHz) and the music is far from being a sinusoid!

 

[dlaloum]

You need a lot of power for peaks.
It depends a lot of what music you listen to. Is it EDM or is it "girl & guitar".. -Crest factor plays a role.
Have you got full range speakers capable of low bass and have you applied DSP or room correction.
It is obviously not a "red herring" if the amplifier is going to supply a 9 dB boost from 20 - 80 Hz or if it's not.


From the link in my signature reg. CF-->

I was assuming a peak (crest factor) of 20db, as that is the standard for theatres/home theatres. - which would equate to your crest factor of CF=20 (I assume?)

With reference level at 85db, peak levels are therefore 105db

Regardless of what EQ has been applied, and whether DSP, etc is in use... the end result is going to aim for the ability to output 85db continuous and 105db peak

If we measure based on the 105db peak - we are providing or a massive crest factor / peak.

Based on Archea's listening distance of around 12ft (4m) - attenuation would be around 12db for distance (not taking into account the impact of reflections... which will potentially boost things)

With his 92db/wm speakers, we require:

1W @ 1m for 92db
2W @ 2m for 92db
4W @ 4m for 92db (this being his listening distance

Without getting too complicated, let's assume 2 speakers, a conservative assumption as there will be 3 mains, then surrounds and heights... so in actual use this is a very very conservative estimate.

two speakers gives you a 3db boost, so the previous 4W for 92db, becomes 4W for 95db

We want to get to 105db (roughly) to provide the necessary peak headroom (crest factor), each 3db increase doubles the power needed

95db @ 4W
98db @ 8W
101db @ 16W
104db @ 32W
107db @ 64W

So taking a probably excessively conservative estimate.... 32W is about what is needed

To cater for "difficult" speakers that have low impedances/high phase angles, the amp should be capable of circa 32W@8ohm, 64W@4ohm and 128W@2ohm (roughly) - as a rule of thumb an amp that can deliver the 128W@2ohm, will do fine on the easier loads.

Most amps have plenty of power @ 8ohm - more than anyone will need, but fail when it comes to 2 ohm... (and many speakers will never need 2 ohm ability, if theire impedance is within the 8ohm to 6ohm range)

Knowing that my speakers are "difficult" I organised a completely over the top excessive power amp, as I wanted to see whether it was any different from my very capable Quad 606 amp... which delivers 135W@8ohm but can only provide 90W@2ohm.
Extended listening sessions with either of the two amps, did not indicate any substantive difference between the two... so for my use case the 90W@2ohm is more than ample. I tend to listen at around 75db / 95db peak, so I need roughly 1/8th the power that Archaea does for his 105db peaks, within the same configuration....

People do tend to exaggerate the need for raw power, and ignore/overlook the need for current.

AVR's and AV amps for the most part deliver copious amounts of power, (way more than needed) but frequently fall in a heap when asked to deliver substantial amounts of current - even at much lower power levels.

The Crown XLS and DCi series (drivecore) are actually really good at delivering current, and are rated at 2ohm...
I wouldn't hesitate to use a DCi 4|300N in my setup.

And yes it is nice to have more than 8x the required power in reserve.... (as I do) but when evaluating a purchase, perhaps the focus should be on what is actually needed... and consciously being aware, that more than that is in fact redundant.

(on the other hand an amp that is idling along at 4W when capable of 400W, is going to run nice and cool, and likely to have a long and healthy life!)

 

[Deleted member 48726]

I was assuming a peak (crest factor) of 20db, as that is the standard for theatres/home theatres. - which would equate to your crest factor of CF=20 (I assume?)

With reference level at 85db, peak levels are therefore 105db

Regardless of what EQ has been applied, and whether DSP, etc is in use... the end result is going to aim for the ability to output 85db continuous and 105db peak

You can't ignore EQ and DSP correction and using a fixed theoretical speaker sensitivity from 20-20.000 Hz (my comment on the taste of music, EDM vs. girl & guitar)

I also think you made some error in your calculation?

Peak SPL Calculator

I do like your practical approach though with the pro amp. I do that myself.

 

[charlielaub]

I don't know what sort of music you listen to, but very little recorded music has a crest factor as high as 20dB...

 

[Archaea]

There is no accommodation for level matching a bit lower for each individual speaker trim in regards to THX level matching a whole HT system. IE I don’t get to chose reference is 102dB per speaker instead of 105dB if two speakers are being SPL calibrated. ( The anticipated sum of 105dB from two 102dB speakers is not considered in SPL matching). (Though that may be considered by the mixer or mastering). Each speaker in the HT room needs to be calibrated to hit 105dB at MLP individually and is calibrated by -20dbfs test tone at 85dB to do so, or internal test tone to 75dB. Put another way — since I have 15 speakers I don’t get to set them to
1 speaker - 105dB
2 speaker - 102dB
4 speaker - 99dB
8 speaker 96dB
16 speaker 93dB
That is NOT how it works for home theater calibration. Else your THX reference volume would be very quiet instead, and as you know from going to a premium commercial theater option with THX calibration — that is not the case.
So we don’t need to consider SPL summing into the SPL calculations for this purpose. It’s always just one speaker for the purpose of calculating power requirements for a home theater setup.


Also EQ certainly must be taken into the equation. I apply manual PEQ and I boost bass on all 15 of my speakers by 3dB using the Marantz tone control, and then apply a very small smiley face EQ beyond that with the Marantz graphic equalizer. 3dB is double the power requirement in the bass region. I use an identical 90Hz crossover for all 15 speakers and this is where it gets hairy because I don’t know how much power requirement that knocks off, and it might be quite significant?

This is before EQ (or 3dB bass boost) for my front 3. (But not counting the 90Hz crossover point). My front three speakers are built into a false wall behind the acoustically transparent screen, with a storage room behind that wall, so they don’t get boundary re-enforcement.

 

[Deleted member 48726]

I don't know what sort of music you listen to, but very little recorded music has a crest factor as high as 20dB...

https://www.aes.org/par/c/#cps

crest factor The term used to represent the ratio of the peak (crest) value to the rms value of a waveform measured over a specified time interval. For example, a sine wave has a crest factor of 1.4 (or 3 dB), since the peak value equals 1.414 times the rms value. Music has a wide crest factor range of 4-10 (or 12-20 dB). This means that music peaks occur 12-20 dB higher than the rms value, which is why headroom is so important in audio design.

There's also this thread-->

Crest factor - how detectable is it?

On this page there are two samples of music, one with a 20dB crest factor and another of the same piece with the crest factor trimmed by 6bB. The author feels that no one should be able to pass a double blind test comparing the two files. On my system at home I feel I can pretty easily identify...

www.audiosciencereview.com

I would think that in home cinema the crest factor can be even higher yet. -Silence-->Explosion. But then again you wouldn't need much power in the silent part.. Home cinema THX experts would know a lot more about this than me.

 

[Spkrdctr]

There is no accommodation for level matching a bit lower for each individual speaker trim in regards to THX level matching a whole HT system. IE I don’t get to chose reference is 102dB per speaker instead of 105dB if two speakers are being SPL calibrated. ( The anticipated sum of 105dB from two 102dB speakers is not considered in SPL matching). (Though that may be considered by the mixer or mastering). Each speaker in the HT room needs to be calibrated to hit 105dB at MLP individually and is calibrated by -20dbfs test tone at 85dB to do so, or internal test tone to 75dB. Put another way — sinceI have 15 speakers I don’t get to set them to
1 speaker - 105dB
2 speaker - 102dB
4 speaker - 99dB
8 speaker 96dB
16 speaker 93dB
That is NOT how it works for home theater calibration. Else your THX reference volume would be very quiet instead, and as you know from going to a premium commercial theater option with THX calibration — that is not the case.
So we don’t need to consider SPL summing into the SPL calculations for this purpose. It’s always just one speaker for the purpose of calculating power requirements for a home theater setup.


Also EQ certainly must be taken into the equation. I apply manual PEQ and I boost bass on all 15 of my speakers by 3dB using the Marantz tone control, and then apply a very small smiley face EQ beyond that with the Marantz graphic equalizer. 3dB is double the power requirement in the bass region. I use an identical 90Hz crossover for all 15 speakers and this is where it gets hairy because I don’t know how much power requirement that knocks off, and it might be quite significant?

This is before EQ (or 3dB bass boost) for my front 3. (But not counting the 90Hz crossover point). My front three speakers are built into a false wall behind the acoustically transparent screen, with a storage room behind that wall, so they don’t get boundary re-enforcement.
View attachment 334223View attachment 334237View attachment 334239View attachment 334243

Jeepers, I guess you have passed the normal 5.1 setup in the living room or a good quality sound bar with sub. I see you have gone way over $2000 on your set up!

 

[dlaloum]

There is no accommodation for level matching a bit lower for each individual speaker trim in regards to THX level matching a whole HT system. IE I don’t get to chose reference is 102dB per speaker instead of 105dB if two speakers are being SPL calibrated. ( The anticipated sum of 105dB from two 102dB speakers is not considered in SPL matching). (Though that may be considered by the mixer or mastering). Each speaker in the HT room needs to be calibrated to hit 105dB at MLP individually and is calibrated by -20dbfs test tone at 85dB to do so, or internal test tone to 75dB. Put another way — since I have 15 speakers I don’t get to set them to
1 speaker - 105dB
2 speaker - 102dB
4 speaker - 99dB
8 speaker 96dB
16 speaker 93dB
That is NOT how it works for home theater calibration. Else your THX reference volume would be very quiet instead, and as you know from going to a premium commercial theater option with THX calibration — that is not the case.
So we don’t need to consider SPL summing into the SPL calculations for this purpose. It’s always just one speaker for the purpose of calculating power requirements for a home theater setup.


Also EQ certainly must be taken into the equation. I apply manual PEQ and I boost bass on all 15 of my speakers by 3dB using the Marantz tone control, and then apply a very small smiley face EQ beyond that with the Marantz graphic equalizer. 3dB is double the power requirement in the bass region. I use an identical 90Hz crossover for all 15 speakers and this is where it gets hairy because I don’t know how much power requirement that knocks off, and it might be quite significant?

This is before EQ (or 3dB bass boost) for my front 3. (But not counting the 90Hz crossover point). My front three speakers are built into a false wall behind the acoustically transparent screen, with a storage room behind that wall, so they don’t get boundary re-enforcement.
View attachment 334223View attachment 334237View attachment 334239View attachment 334243

You can't ignore EQ and DSP correction and using a fixed theoretical speaker sensitivity from 20-20.000 Hz (my comment on the taste of music, EDM vs. girl & guitar)

I also think you made some error in your calculation?

Peak SPL Calculator

View attachment 334145

I do like your practical approach though with the pro amp. I do that myself.

Nice calculator - easier than doing it manually!

I cheated with the amps... I looked at what the speaker designer used to use when demoing those speakers at Audio shows.... it was a Class D audiophile amp, rated at 500W@8ohm and able to drive difficult loads down to 2ohm and below (Spectron Musician III) - then I went looking for something that was in a similar ballpark, without needing a mortgage to pay for it...

Since then I have applied more science to the analysis - after observing what the LED power level lights on the Crown were telling me - it is clear that the level of power is massive overkill!

 

[jhaider]

I have some qualms about the numbers you've presented.
My front speakers drop off about 10dB measured from 11-12 foot distance to main listening position.
Your numbers also don't account for EQ application. (Audyssey can boost up to 9dB for instance -- each autoeq system has their own limits - if you choose to use them) 9dB of boost can eat up headroom fast,
Finally, I do listen to hours on end at true reference in my theater, so this is something I value.

Have you measured how much power your speakers actually draw when you're listening? If memory serves, Audio Architect will tell you. If you can't find it, let me know and I'll fire up the stupid windows thingy and try to find it in the software myself.

As for your listening habits...that does not seem an approach conducive to long-term preservation of hearing. Also keep in mind that "reference" for a small room is lower SPL than "reference" in an auditorium.

 

[Archaea]

Have you measured how much power your speakers actually draw when you're listening? If memory serves, Audio Architect will tell you. If you can't find it, let me know and I'll fire up the stupid windows thingy and try to find it in the software myself.

As for your listening habits...that does not seem an approach conducive to long-term preservation of hearing. Also keep in mind that "reference" for a small room is lower SPL than "reference" in an auditorium.

When speakers are playing clean, reference is loud, but not painful. It’s exhilarating. I’ve had demo nights for friends and family soo many times. Recently had a movie night for a couple families from church with about 10 kids. Played a half hour of demo clips at full reference volume with all parents in the room, and everybody including the kids and women were all grins and wows, and yelling in excitement after each clip. We watched the full movie at -6dB to avoid any concerns for the youngest kids hearing. If I keep my system no higher than reference my slight tinnitus stays in check. When I go above reference, which I avoid, is when I encounter issues. Lately I have borrowed Storm audio processor and a Trinnov and before we got the volume limiters engaged we had an accidental runaway volume issue because an Apple remote got stuck on raise volume and that’s the loudest it has EVER been in here. My ears left ear is still ringing two weeks later. That is NOT a normal occurence
My omnimic was hooked up and actively measuring, and it measured 125db max and 135dB peak and it was clipping the mic input and the software was saying in big red overlay — input overload, That was not enjoyable. I keep it in check usually. I limit to to 0 in the GUI options on the Marantz to protect against and accidental surprise.

I’ll check out the audio architect software. I used it to input the CBT 70J-1 tunings and then haven’t revisited. But would software like that be measuring true dynamic peak or just RMS/averages?

 

[jhaider]

When speakers are playing clean, reference is loud, but not painful. It’s exhilarating.

That may be your lived experience, but it's orthogonal to my point about hearing health and longevity rather than pleasure.

Personally, watching a sequence movie clips is not something strikes as more tedious than fun regardless of SPL. (And that kind of thing does help explain why modern movies tend to suck - people who want to tell stories have gravitated to writing for TV and people who want to watch movies really just want the bombastic shit anyway so who cares about the writing; a plot is only going to get the PRC censors interested anyway) But everyone has their own ideas of enjoyable activities. I'd expect a rather better experience in your home than in a movie theatre, though. I took one of our daughters to see the Taylor Swift concert movie (I think the only time I'd stepped in a movie theater since before the pandemic), and despite being an allegedly flagship "Dolby Cinema" room the sound was just terrible. They had transducers turned up so loud the "bass" was basically just a butt and calf massage. It was also quite harsh, though that could have been the mix.

I’ll check out the audio architect software. I used it to input the CBT 70J-1 tunings and then haven’t revisited. But would software like that be measuring true dynamic peak or just RMS/averages?

Don't recall, though my guess is the latter.

Curious, have you checked what the CBT 70J-1 tunings are? The CBT-50 and CBT-100 tunings were unfortunately just limiters. No frequency response correction based on anechoic data.

 

[Archaea]

That may be your lived experience, but it's orthogonal to my point about hearing health and longevity rather than pleasure.

Personally, watching a sequence movie clips is not something strikes as more tedious than fun regardless of SPL. (And that kind of thing does help explain why modern movies tend to suck - people who want to tell stories have gravitated to writing for TV and people who want to watch movies really just want the bombastic shit anyway so who cares about the writing; a plot is only going to get the PRC censors interested anyway) But everyone has their own ideas of enjoyable activities. I'd expect a rather better experience in your home than in a movie theatre, though. I took one of our daughters to see the Taylor Swift concert movie (I think the only time I'd stepped in a movie theater since before the pandemic), and despite being an allegedly flagship "Dolby Cinema" room the sound was just terrible. They had transducers turned up so loud the "bass" was basically just a butt and calf massage. It was also quite harsh, though that could have been the mix.



Don't recall, though my guess is the latter.

Curious, have you checked what the CBT 70J-1 tunings are? The CBT-50 and CBT-100 tunings were unfortunately just limiters. No frequency response correction based on anechoic data.

Agreed on the CBT 70j-1 tuning, it appears it’s just a HPF at 55Hz and a Voltage limiter.

And also agreed on some of the premium commercial cinemas sound missing the mark. Yes, I humbly submit my HT sound is better than any commercial cinema I’ve personally visited. Picture is better too — If only the screen size was as large!!!!

Our local enthusiast group still meets up for the occasional big premiere at the local Dolby cinema or IMAX. Still something special about a HUGE screen for a movie like Top Gun Maverick.


If you ever pass through Kansas City area, send me a PM and I’d be happy to demo my room. Standing invite.

 

[patoulol]

Good morning. a friend lent me a 4/300N DCI but I have a ground loop. no problem with the CT 4150 on the other hand