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Advice for Beginners - consider this test from an audio club

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It was great when the FTC came out with those home stereo standards, replacing the extreme “peak music power” numbers that we used to see.  However, as I understand it, there are no standards for multi-channel receivers and amplifiers.  Stereo amps always run on 2 channels, but AVRs can run on 2, 3, 4, 5, 6, 7, 9, or even more channels, so the 2-channel rating of an amp becomes meaningless when 7 or 9 channels are trying to pull lots of power through a single power supply.

 

100 watts per channel is a typical rating, but it’s only applicable when driving 2 channels.  If the AVR has 7 channels, the average buyer assumes that this means 100 watts x 7, for a total of 700 watts, but the real total may be less than 300 watts.  When driving 5 channels, it’s not unusual for the power to drop to 55 watts per channel.

 

Accordingly, the FTC should come out with new multi-channel standards, since multi-channel receivers and amplifiers are the dominant type of home sound system these days, and have been for over a decade.  This will be old news to many of you, but some novices may not know this yet.

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1 hour ago, Islander said:

It was great when the FTC came out with those home stereo standards, replacing the extreme “peak music power” numbers that we used to see.  However, as I understand it, there are no standards for multi-channel receivers and amplifiers.  Stereo amps always run on 2 channels, but AVRs can run on 2, 3, 4, 5, 6, 7, 9, or even more channels, so the 2-channel rating of an amp becomes meaningless when 7 or 9 channels are trying to pull lots of power through a single power supply.

 

100 watts per channel is a typical rating, but it’s only applicable when driving 2 channels.  If the AVR has 7 channels, the average buyer assumes that this means 100 watts x 7, for a total of 700 watts, but the real total may be less than 300 watts.  When driving 5 channels, it’s not unusual for the power to drop to 55 watts per channel.

 

Accordingly, the FTC should come out with new multi-channel standards, since multi-channel receivers and amplifiers are the dominant type of home sound system these days, and have been for over a decade.  This will be old news to many of you, but some novices may not know this yet.

It's at this point that AVR owners can say: "Thank goodness I have Klipshorns and LaScalas for HT." Where 1 watt per channel get you reference level or better.

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12 hours ago, Islander said:

It was great when the FTC came out with those home stereo standards, replacing the extreme “peak music power” numbers that we used to see.  However, as I understand it, there are no standards for multi-channel receivers and amplifiers.

 

This is correct. FTC standards do not apply to home theater equipment, pro sound, or auto sound.

 

QSC provides FTC numbers for some of their amplifiers, and some home theater products give FTC numbers for 2 channel operation, but that's not commonly done.

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5 minutes ago, Don Richard said:

 

This is correct. FTC standards do not apply to home theater equipment, pro sound, or auto sound.

 

QSC provides FTC numbers for some of their amplifiers, and some home theater products give FTC numbers for 2 channel operation, but that's not commonly done.

 

Yamaha AVR specs list the power output for 1 channel driven, and for 2 channels driven, but after that, you're guessing what's happening when you're driving 5, 6, 7, or 9 channels.

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34 minutes ago, Islander said:

 

Yamaha AVR specs list the power output for 1 channel driven, and for 2 channels driven, but after that, you're guessing what's happening when you're driving 5, 6, 7, or 9 channels.

This is why I use a Yamaha AV Pre Pro with XLR connectors that feed my separate ClassD Power amps. Bottomless Bass from seemingly "unlimited" headroom with ALL HORNS, which is the Pinnacle of audiorealism.

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What the hell are you guys doing? Trying to turn a lame *** thread into something informative? How dare you..........

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On 2/10/2019 at 3:24 PM, Don Richard said:

In general, amps with a stiffly regulated power supply will have less dynamic power output than amps with unregulated or less stiffly regulated power supplies.

 

 

 

This is not correct.  If you look at a typical class AB amp you will see that the DC current draw can increase very significantly between idle and full/peak output.  With an unregulated power supply the voltage will likely sag under such demands which will cause a decrease in power capability and, if the sag is great enough, an increase in distortion due to a change in the tube operating parameters.  We always use very highly regulated supplies in such amps to ensure a steady plate and screen voltage under those conditions. 

 

 

Maynard

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23 hours ago, tube fanatic said:

We always use very highly regulated supplies in such amps to ensure a steady plate and screen voltage under those conditions. 

 

Most test results I've seen are for solid state amplifiers, and stiffly regulated supplies with those result in less dynamic headroom. Can you show me a schematic of a very highly regulated supply in a typical tube amp? Mostly I've seen filter circuits with an input cap, a choke and an output cap, but it's been years since I've messed with tube circuits. I have built tube circuits that had regulated bias voltage, but the B+ had no regulators for the most part.

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23 hours ago, Don Richard said:

 

Most test results I've seen are for solid state amplifiers, and stiffly regulated supplies with those result in less dynamic headroom. Can you show me a schematic of a very highly regulated supply in a typical tube amp? Mostly I've seen filter circuits with an input cap, a choke and an output cap, but it's been years since I've messed with tube circuits. I have built tube circuits that had regulated bias voltage, but the B+ had no regulators for the most part.

 

No time to draw a schematic but you can research multi section choke input filters, as well as gas and zener regulated screen supplies.  That will give you an idea of what I am talking about.  

 

Maynard

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There were two local guys in the late 60s who made a no holds barred stereo PP class A tube amp that featured regulated DC filament power and regulated B+, two separate channels in one enclosure with a cable connecting the power supplies to the amplifier. The power supply was bigger and heavier than the amplifier by quite a bit.

 

That, and the one you linked are the only ones I've seen like that to date. Any idea what the dynamic headroom is for your amplifier?

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With a supply as stiff as that appears to be (why?), likely less than a dB.  Rated power is all it makes under any circumstance, though in this case there aren't really any "ratings" anyway, plus it's an SET, so there's that...

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plus it's an SET, so there's that...

 

Yeah, and that's the best part.........

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11 hours ago, glens said:

With a supply as stiff as that appears to be (why?)

In the article, Loesch refers to a paper that I looked up and read a while back that explains why a very well regulated supply is a good idea, even for a SET amp.  My amp will use a (different) filament regulation circuit, one for each 300B, and one for both C3Ms, (Rod Coleman’s), so all voltages going to the circuit will be regulated.  Seperate power supply chassis with an umbilical to the circuit chassis, so no AC in the circuit chassis.  

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I hope the beginners are paying attention. There will be a test on page 200.🤗

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What, it made it to 100? May the dream come alive...dreamers.

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Just hooked up an 8802A Pre to my amp two nights ago. The refurb prices fell enough I figured it was time to pull the trigger.  Coming from using a Denon 4311 AVR as a pre, obviously I was pretty excited.   I cant remember when I bought the 4311, but Im thinking its a good 8+ years old.   Anyway, the 8802 has more definition and clarity. The tracks in the content seem to be more layered, but not too analytical.   Its not as wet sounding and the mid and top end is more controlled.  From my usual round of music of ALAC tunes, I immediately could pick out background items that were more covered before.  I think there may be something to these newer AK 4490 DAC's and source topo's and whatnot with this newer unit.  I have only used it at upper conversation levels so far, but hopefully I can open the taps up more this weekend.    On a side note, I cant read anything on the remote. It feels small and delicate compared to the old Denon.  The GUI is ok, but a few things that have obviously changed over the years in GUI's like quick access to the sub being turned off and on in direct pure mode isn't simple like the old Denon.  I wish I could compare this newer Pre to a newer or modern AVR as a better comparison. 

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Think I missed something, could all you guys plz repeat all that :)

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