"The Wire AMP" Class A/AB Power Amplifier based on the LME49830 with Lateral Mosfets - Page 52 - diyAudio
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Old 15th December 2011, 12:40 PM   #511
opc is offline opc  Canada
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AndrewT, TheShaman and Pietre t:

I think we're starting to get a little OT with this.

Hypertune:

I have an Anthem Statement A2 here that with a little extra bias and a fully regulated supply does measure around the same and sometimes slightly better than The Wire. It's not exactly a cheap amplifier though, and the regulated supply is actually a bench top lab supply which isn't cheap either!

Otherwise, if you're alright with lower output power, I have a little treat in the works that should give about 16W output into 8 ohms and gives the same distortion and noise performance of the SE-SE headphone amplifier. That would be about 20dB lower noise floor, and at least 10dB better distortion figures.

I'll let people know more when I have a more aesthetically pleasing prototype built up

Cheers,
Owen
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Old 15th December 2011, 12:51 PM   #512
AndrewT is offline AndrewT  Scotland
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Hi OPC,
some are championing a particular amplifier topology and suggesting, based on dubious data, that that topology offers better value for money than your offering.

Their whole argument is foundless. We should all disregard that off topic interjection. In it's present form the data for the alternative cannot be substantiated.

Maybe we should ask the Moderators to remove all references to switching amplifiers from this thread.
Do we need a vote on that?
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Old 15th December 2011, 12:53 PM   #513
npdot is offline npdot  United States
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Owen,

I have been trying to catch up on many years of inactivity from diy power amp projects by reading both Cordell's and Self's impressive textbooks on the subject. Please clarify for me the definition of class B vs class A/B. It seems that Mr. Self's "properly biased" class B is what we (on this forum) are calling class A/B. And, when we use the term class B, we mean OPS Iq approximately equal to zero.

Thanks,
Neel
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Old 15th December 2011, 01:00 PM   #514
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Quote:
Originally Posted by AndrewT View Post
Maybe we should ask the Moderators to remove all references to switching amplifiers from this thread.
Do we need a vote on that?
Does not seem necessary to me.
Floridabear was the first (post#481) coming up with a distortion curve of the ncore amp.
You, Andrew T, being the first asking for more information... (post#482).
But I agree with Owen: too much attention for class d here; let's stick with the Wire Amp.
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Old 15th December 2011, 01:01 PM   #515
qusp is offline qusp  Australia
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Quote:
Originally Posted by opc View Post

Otherwise, if you're alright with lower output power, I have a little treat in the works that should give about 16W output into 8 ohms and gives the same distortion and noise performance of the SE-SE headphone amplifier. That would be about 20dB lower noise floor, and at least 10dB better distortion figures.

I'll let people know more when I have a more aesthetically pleasing prototype built up

Cheers,
Owen
awesome, sounds like this could be a nice amp for the likes of the HE-6 and similarly inefficient planar headphones as well. i get the feeling youve been playing around with franken-wire PCBs?
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Old 15th December 2011, 01:01 PM   #516
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Owen admittedly left the door open a little by his "no class D amp..." assertion, but I think we've now exhausted that topic. I apologize if I derailed the thread. Let's get back to the Wire!
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Old 15th December 2011, 01:20 PM   #517
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by npdot View Post
.......... by reading both Cordell's and Self's impressive textbooks on the subject. Please clarify for me the definition of class B vs class A/B. It seems that Mr. Self's "properly biased" class B is what we (on this forum) are calling class A/B.
Yes D.Self states quite clearly what "his definition" of ClassB means.
It is exactly the equivalent to the generally accepted Optimally biased ClassAB BJT amplifier.

ClassB is not when bias is zero.

ClassA is when all devices take an active role in controlling the output current over the full cycle of the AC waveform.
This is quite different from: ClassA is when the devices never turn off.

ClassAB is when the devices conduct for more than 180degrees and less than 360degrees of the AC waveform cycle.

ClassB is when the devices conduct for 180degrees of the AC waveform cycle. This is different from: when the output bias is zero.
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Old 15th December 2011, 02:00 PM   #518
opc is offline opc  Canada
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npdot:

AndrewT is spot on. I'm not sure why Mr. Self would complicate the issue by introducing "his definition" of a class B, but I'm sure there was a point to be made in there somewhere.

As mentioned, bias can be a complicated way of looking at the issue, when you should be focusing on the amount of the output angle each device conducts.

Regards,
Owen
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Old 15th December 2011, 02:13 PM   #519
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Andrew,

Thanks for the clarification of Mr. Self's definition of class B, and for reminding me that he clearly states the definition. Could you go one step further? After I posted the question, I realized that the definitions might be viewed differently for BJT vs FET OPS's. For example, in post #466 Owen refers to his figure 5 as "FFT @ 1W, Class B (not quite true class B about 5mA bias)".

Your help is appreciated.
Neel
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Old 15th December 2011, 02:29 PM   #520
npdot is offline npdot  United States
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Owen & Andrew,

I realize that my questions are a little down in the weeds. My objective is to understand what I'm reading. Output angle is very clear.

Also, I suspect that for the better informed, there is little confusion over "casual" vs. "academic" terminology. The Cordell and Self books seem quite academic but not totally consistent with each other in a few terms.

Thanks again.
Neel
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