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Class D popping up everywhere. Innovation?

#121
greenboy said:
Yeah, it's in a lot of small low-draw devices as well. Again, with the advent of modules and some practically single-chip miniature solutions it looks like Class D is going to predominate across all tiers eventually.
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Yes, cell phones and other small portable devices use class D to maximize battery life.
 
#122
Mike19 said:
FYI: In the world of hi-fi stereo there has been a long standing debate/disagreement over tubes vs. SS vs hybrids. Same thing with whether or not pre-amps should be in a seperate box from the amp(s).

The general hi-fi consesus is that tubes sound best but are too expensive, too heavy and require maintainence.
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Nope - that is not the general consensus that tubes "sound" better.
Check the HiFi forums - class-d is big in the HiFi arena. You can get truly transparent SS amps that have no "sound" they just amplify.

Cell phones, hearing aids, mp3 players - all are moving to class-d for better fidelity and longer battery life.
 
#123
If I recall, the current Powerlight series tops out with Class D where the Class H was doing the less powerful configs. Proably others too, but I haven't needed an amp lately so I haven't checked. And I wouldn't be surprised if QSC's presence in the SR enclosure market isn't shored up by some Class D plate amp/DSP products.
 
#124
greenboy said:
And I wouldn't be surprised if QSC's presence in the SR enclosure market isn't shored up by some Class D plate amp/DSP products.
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The K Series powered loudspeakers are class D, with onboard DSP for voicing, crossover, protection, et al.
 
#125
... Pretty much any SR company that wants to be taken seriously has Class D active enclosures these days, and yep: DSP features. JBL gets theirs designed at Crown as both are Harmon companies.

Both JBL and QSC seem to have a lot of fans among the home enthusiast DIY crowd too, thanks to their great waveguides : }
 
#126
A lot of misinformation going around and I am surprised by Mr Lee who appears to be in the business. The efficiency of a class D amp is totally from the switching power supply that takes only the power required by the amp at any moment so if there is a millisecond of pause in the signal the supply draws no power. A (normal) amp is drawing current continuously and is filling the caps for the amp to draw from. This has no relationship to the power amp transistors. There is no lower requirements for them because of class D. Remember class D is a power supply issue only!
 
#127
Bellair Audio said:
A lot of misinformation going around and I am surprised by Mr Lee who appears to be in the business. The efficiency of a class D amp is totally from the switching power supply that takes only the power required by the amp at any moment so if there is a millisecond of pause in the signal the supply draws no power. A (normal) amp is drawing current continuously and is filling the caps for the amp to draw from. This has no relationship to the power amp transistors. There is no lower requirements for them because of class D. Remember class D is a power supply issue only!
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You cannot judge what is misinformation if you are ignorant. You don't know power supplies or amplifier classes. Unless you can stick to asking questions, please learn something before you post again.
 
#128
Bellair Audio said:
A lot of misinformation going around and I am surprised by Mr Lee who appears to be in the business. The efficiency of a class D amp is totally from the switching power supply that takes only the power required by the amp at any moment so if there is a millisecond of pause in the signal the supply draws no power. A (normal) amp is drawing current continuously and is filling the caps for the amp to draw from. This has no relationship to the power amp transistors. There is no lower requirements for them because of class D. Remember class D is a power supply issue only!
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This is just not the case. Class D is an output mode. SMPS is a type of power supply. You often see them together but they are 2 different things.

You can have a class D amp with a conventional power supply.

You can have a class A amp with a SMPS.
 
#129
bongomania said:
You fail even with that attempt at qualifying your statements. There are many DSP preamps that provide tone and amplitude coloration and effects across the entire spectrum of squeaky clean to lightly colored to heavily effected, regardless of your interpretation of the word "distortion". Even if you backtrack and say you only meant power amps, many of the combined amp heads and powered cabs use DSP in their handling of the signal on its way into the final current-boosting stage.
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DSP is a processing stage and has no relationship to amplification. This might be in a preamp circuit but the issue is amplifying digital signals. The analog signal is turned to digital, processed, and turned back to analog and then amplified by the pre amp.
 
#130
Bob Lee (QSC) said:
Yes, that's the PowerLight 380.

[Invalid or Expired Link Removed]
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Nice amp but another issue I had with my 4050hd was amperage draw at high output levels which can trip circuit breakers.
My current class D amp (Crest Audio CD3000) puts out 1500 watts mono at 2 and 4 ohms(weird) but only draws 7 amps. I used a amp meter to confirm this and at first stage clip levels, the amp drew 7.8 amps.
After checking spec's on the QSC PL340, the spec's show an amperage draw at 12 amps at 1250 watts at 4 ohms. I would be interested in checking out the QSC amp due to my past experiences with your products but...

Why would there be a significant amperage draw difference between the two amps?
 
#134
Yes there does seem to be more than a little confusion(with a bit of rudeness tossed in....)


projectMalamute said:
You are confusing the power supply with the output stage. Most class A or class AB transistor power amps have no output transformer, the transformer is for the power supply.

That's what he said in #90:
"Class A & B have transformers and large capacitors for a power supply so the lightweight amps are class D or a variation of D."

"Poor reading comprehension or memory retention on even your own text from a few minutes back, eh? ; } Look at the word I bolded when I quoted your post: PREAMP. And that was exactly what I addressed: PREAMPS - and not AMPS. You brought PREAMPS up, in case you still are having trouble with this line of thought."

The point is "amplifying" not where it's done, pre, post, etc. There aren't any that are digital.
The nearest thing I can find is that "digital preamp" means the amp accepts digital inputs and outputs analog signal. It uses a D-A converter. That ain't "digital" amplifying. It amplifies an analog signal.
I found some good info here:
[Invalid or Expired Link Removed]

I also found more here:
http://www.puredigitalaudio.com/digitalamplifiers/index.shtml
They(true digital amps)(no converters) apparently never got off the drawing board, as stated in #87.

"Class D does not require a transformer, nor do other transistor amps, except in the power supply if the amp runs on AC (or with rail voltages that differ from the supplied DC voltage)."

That's what he said......
"The power supply is a different matter and that is what makes class D different in that it does not REQUIRE a transformer"(#90).

"You are confused about transformers and amp classes."

How, exactly? It appears that Bellair ain't the only one here....

This is quite interesting so far, but could we leave out the rudeness?

Josh
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#137
fourstringburn said:
Yes my current amp is a class D AMP.
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Class D is more electrically efficient. For a given amount of output power an amp could have a smaller power supply, smaller heat sinks, fewer output transistors, etc. Or it could yield a more powerful amp for a given amount of AC service.
 
#138
fourstringburn said:
aNOTHER strange THING ON MY AMP (CREST AUDIO CD 3000 CLASS D STEREO) Why does it put out the same wattage at both 2 ohms and 4 0hms whether in bridged or mono mode?
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Probably a form of current limiting. Some class D amps have that.
 

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