What the heck? It's less than lunch!

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#7
Mark2727 said:
Well, you'll have to educate me on what qualifies as a class D. And for that matter a "chip amp".

I don't think I know the difference really.

I have a Jerry's Electronics Amp too, and a Sure. I don't think there's inductors on either of those.

Mark
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Jerry's is tpa3122 which is a class D and has inductors (ferrite core with wire around them, vertical deals). Small Sure 8 w board gets away with tiny ferrite bead as inductor. Bigger Sures have surface mount inductors that look like a black cube.

Class D is a pulse width modulation switching amp where the power transistor swings from on to off at switching freq usually 400 khz or up. The duration of how long it switches on controls amplitude and inductor and capacitor at output filter out the fast switching transients.
 
#10
Note in the diagram from Ebay it shows a 12V+ voltage and a corresponding 12V- this is a technical error. It is not a split supply.....the supplied instruction manual should clarify this....consult the datasheet that is posted here.
Don't expect true quality sound from this.....I heard somewhere that all other things equal, humans can detect THD levels above 0.5 .....this limits the bulk of the power output( >1W) above this level.


___________________________________________________Rick.......
 
#11
Good point. I think they meant 12V supply positive and supply negative but it could easily cause confusion. And yes, the chip's datasheet specs aren't very exciting.
The good news (besides the astonishing price) is the included heat sink can probably handle that 1W output.
I admit I'm still wondering what Whi-fi is.😕

Anyone agree that this thread should probably be moved to the Chip Amp forum?
 
#12
Stay tuned

Hi everyone,

I will let you know if this is a thumbs up or thumbs down when it arrives.

I read the Wikipedia article. I still don't think I could tell you the difference between a chip amp and class D. It's beyond my scope right now -- and 56 year old brain maybe.

Tubes, solid state, and "the rest" is how I classify it. I've heard good and bad in all three.

Hope this one is good. And you guys all buy one before they raise the price. :shhh:

You just never know what cheap and good thing you may happen across. I won't dismiss it with a data sheet. When I hear it, I'll decide then.

Remember, on the bumblebees data sheet. They cannot possibly fly. Theory vs. reality.

Mark
 
#13
its a pretty fundamental operational difference. Class D relies on a fixed and hard switching carrier frequency (can be analogue driven free running or driven by a clock) that is much higher in frequency than the audio. a pulse width modulator (PWM) is imposed over this to create the audio. normal A or AB has frequency and amplitude modulation, but no carrier. then there are the technological differences; but it has nothing to do with D standing for digital, because it doesnt, D just comes after C, which came after B which came after A...

yeah the bumblebee thing is a myth that simply wont go away

Often this bumblebee story is used to discredit scientific conclusions about the impossible nature of supernatural events or feats.
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#14
Mark2727 said:
Remember, on the bumblebees data sheet. They cannot possibly fly. Theory vs. reality.

Mark
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Actually it has been proven that they can fly and how. The hypothesis that it has at any time even been discussed in science that they couldn't is inane non-sense as is often the case with urban myths.

There's no "other stuff". There's just tubes and transistors. Class A, AB, D or whatever can be made with either.
 
#15
Not sure why someone is saying power output is limited to 1 watt? That heatsink looks like at least a 10 watt heatsink. Class AB is about 50% efficient so I would guess closer to 10 watts output.

Off topic but not only can the bumblebee fly, it is scientific fact measured in the lab that as an engine and locomotive system, the bumblebee is super super efficient. Based on calories in honey and distance the bee flies, and converting the calories to energy content equivalent in gasoline... the bumblebee gets 4.7 million miles a gallon!

Here is article on flight of bumblebee and its aerodynamics:
Flight Of The Bumble Bee Is Based More On Brute Force Than Aerodynamic Efficiency

Here is article on fuel efficiency of bumblebee:
Bee Vs. Car: Who Gets More Miles Per Gallon? : Krulwich Wonders... : NPR
 
#18
no its not super efficient, well not by insect standards. the first article about bee miles per gallon is for standard honey bees, not bumble bees. Bumblebees as the second article says, have a disconnect between their left and right sides. this feature allows them higher maneuverability in a controlled stall/hover, but means they cannot leverage the energy/efficiency of combined vortices around the body in forward flight. its brute force, the honey bee is much more efficient.

xrk971 said:
Not sure why someone is saying power output is limited to 1 watt? That heatsink looks like at least a 10 watt heatsink. Class AB is about 50% efficient so I would guess closer to 10 watts output.

Off topic but not only can the bumblebee fly, it is scientific fact measured in the lab that as an engine and locomotive system, the bumblebee is super super efficient. Based on calories in honey and distance the bee flies, and converting the calories to energy content equivalent in gasoline... the bumblebee gets 4.7 million miles a gallon!

Here is article on flight of bumblebee and its aerodynamics:
Flight Of The Bumble Bee Is Based More On Brute Force Than Aerodynamic Efficiency

Here is article on fuel efficiency of bumblebee:
Bee Vs. Car: Who Gets More Miles Per Gallon? : Krulwich Wonders... : NPR
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