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#432653 - 06/19/19 03:20 PM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
bman84 Offline
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Registered: 09/29/18
Posts: 181
Loc: Toronto, Ontario
Originally Posted By michael_d
Originally Posted By Mojo
Has your Anthem ignited yet, Michael? All the ADAs I have run cool even with 2400W peaks.


Not yet, but I'm not using ANY of the amps. I have an external ICE base amplifiers. - and they run cool.

I did get my T8 cooling fan. Pretty slick device. I can set it up to start pulling air at any temp or fan speed. I have not had time to watch a movie though, so I don't know if the Anthem's fan will run yet.

I might also add that some of the guys at AVS reported the MRX fan would run, even when using external amps, so this is not a "hot amp" thing, but a processor thing. My MRX fan only came on during movies with multi-channel sound processing.


I'm planning on getting an MRX and doing exactly the same thing. I wonder if there's a way to just 'turn off' internal amplification altogether. Or does it effectively do that by itself when nothing is connected to the binding posts?
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Axiom M5HP,VP180,M3,ADA1000
Anthem MRX 720
SVS SB-3000 (dual)

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#432657 - 06/20/19 09:41 AM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
michael_d Offline
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Registered: 07/23/04
Posts: 4220
Loc: Up yonder
I do not see an option for turning all amp sections off. But, if there is nothing connected to the load side? ...I do not see how they can possibly be "on". I dunno, never really dug into the theoretical operation of amplifiers before.
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#432658 - 06/20/19 10:01 AM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
bman84 Offline
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Registered: 09/29/18
Posts: 181
Loc: Toronto, Ontario
Makes sense. And there wouldn't be a dedicated power supply for the amps that could be switched off independantly.
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Axiom M5HP,VP180,M3,ADA1000
Anthem MRX 720
SVS SB-3000 (dual)

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#432659 - 06/20/19 10:23 AM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
Mojo Online   content
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Registered: 01/21/07
Posts: 6302
They are most certainly on. If you put a voltmeter on the high level output terminals, you'll read a voltage. Of course there's no current because a speaker is not connected.

There are at least two windings (off the main transformer) that supply the power amp section. It would be really cool if those windings could be switched off when using an external amp. The whole unit would be quieter. However, this likely isn't practical because many want an amp for only the front three channels.
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A-LFR/1000-8/500v4x2 coming
1000-2,3,1500-3
100,160,QS10x2,800,M5,M3,M50 v4
had v2
Air N2 (someday)

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#432660 - 06/20/19 12:30 PM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
bman84 Offline
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Registered: 09/29/18
Posts: 181
Loc: Toronto, Ontario
Is the noise a function of the circuit being 'on'? Or the amount of current flowing through it? Or both?



Edited by bman84 (06/20/19 12:31 PM)
_________________________
Axiom M5HP,VP180,M3,ADA1000
Anthem MRX 720
SVS SB-3000 (dual)

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#432661 - 06/20/19 12:48 PM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
Mojo Online   content
axiomite

Registered: 01/21/07
Posts: 6302
Well..first...current doesn't flow because "current" means charge is flowing. smile

The noise is a function of differences in potential (electric fields) and currents (magnetic fields). If you can turn off voltages and currents, the electromagnetic fields are reduced, and so is the noise.

There's also likely some electromechanical noise from the transformer windings humming and if you can turn off a couple of the windings, that noise will get reduced too.

Incidentally, on my Onk, the engineers spent what appears to be a ton of effort on reducing this transformer, and in general, chassis noise. It's a design consideration that often gets ignored. When things are vibrating, and those things enclose charge, stray electromagnetic fields will be created.

_________________________
A-LFR/1000-8/500v4x2 coming
1000-2,3,1500-3
100,160,QS10x2,800,M5,M3,M50 v4
had v2
Air N2 (someday)

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#432662 - 06/20/19 02:19 PM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
Mojo Online   content
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Registered: 01/21/07
Posts: 6302
In Pure Audio mode, my Onk shuts down the display and all analog circuitry associated with video processing.
_________________________
A-LFR/1000-8/500v4x2 coming
1000-2,3,1500-3
100,160,QS10x2,800,M5,M3,M50 v4
had v2
Air N2 (someday)

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#432665 - 06/21/19 12:45 PM Re: AVR or pre amp recommendations? Going 4K [Re: Mojo]
Ian Offline
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Registered: 03/13/01
Posts: 1311
Some interesting discussion here around the right THD+N spec. We conducted an empirical test a number of years ago where we had the test subject sit in the anechoic chamber and listen to test tones (yikes). The operator in the lab would slowly introduce a second tone. We had the subject raise their hand whenever they could detect any change to the test tone. A camera in the anechoic chamber allowed the operator to observe at what distortion level the hand was raised. We did this with quite a few people and the results were very consistent. We introduced tones that were both harmonically related to the fundamental and ones that were not. For the harmonically related tones the distortion level for detection was incredibly high for the 2nd harmonic and dropped off rapidly so by the time you were at the 5th harmonic there was no difference between a harmonically related tone and a non-harmonically related tone. There was also a fairly linear downward detection level with frequency. We are much more sensitive at higher frequencies. The absolute lowest detection level we got was 0.1% for a non-harmonically related tone at 10kHz, and this is with test tones in an anechoic chamber so music masking in a real room would be a much higher level. So here is the problem; the spec does not give you any information about which harmonic. If it is the 2nd or 3rd then a THD+N well above 1% would actually be ok but outside of this caveat the most extreme argument you can make is that it needs to be below 0.1% (how much below is irrelevant). All this said there is another real-world problem that can make even considering the THD+N spec completely irrelevant, and that is if you hit the dynamic limits of your amplifier. Amp clipping is measured in double digits of distortion that will go through the roof with the addition of only a few watts above the clipping threshold. So, the moral of the story is to be sure you have lots of power to spare before worrying about the THD+N spec.
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#432668 - 06/21/19 04:54 PM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
Mojo Online   content
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Registered: 01/21/07
Posts: 6302
Isn't science wonderful? When someone at work gives me their opinion, no matter how sensible and intuitive it may seem, I ask for data. The data always brings new learnings.

Regarding Ian's test, I and others who have listened to my systems, have found that we fatigue easily and object when the highs are distorted. I don't know what level of distortion this represents because I can't measure it but it's always the highs that are real nasty. I also don't know if this is THD or inter-modulation distortion.

Having said all this about the highs, distortion in the lows is nasty in a different way. Although it doesn't fatigue, it negatively affects imaging and soundstage and muddies the sound.
_________________________
A-LFR/1000-8/500v4x2 coming
1000-2,3,1500-3
100,160,QS10x2,800,M5,M3,M50 v4
had v2
Air N2 (someday)

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#432669 - 06/21/19 06:13 PM Re: AVR or pre amp recommendations? Going 4K [Re: michael_d]
Mojo Online   content
axiomite

Registered: 01/21/07
Posts: 6302
I maintain Bose did a lot of things right. No highs and no lows means no objections per the previous two posts. LOL!
_________________________
A-LFR/1000-8/500v4x2 coming
1000-2,3,1500-3
100,160,QS10x2,800,M5,M3,M50 v4
had v2
Air N2 (someday)

Top
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