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Class D Switching Power Amplifiers and Power D/A conversion

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Old 29th April 2009, 03:21 PM   #51
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Eva is absolutely correct, the output devices now will not switch as
efficiently at more then 100 volts. The body diodes are slower and the
gate charge/ capacitance become tougher to drive quickly.
There is also the fact that the resolution of the amplifier decreases
as the rail voltage increases for a given switching frequency.
ie 350khz at 75W or 200W of output.

btw I am using +- 43 volts on the rails of my amplifer
this is good for 225 W rms into 4 ohms
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Old 29th April 2009, 05:26 PM   #52
Eva is offline Eva  Spain
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Quote:
Originally posted by G.Kleinschmidt
Well of course the THD for a 180W amplifier is much lower at only 15W.

Im not sure why you think that a closed loop THD of 0.005% here is particularly exciting, particularly in comparison to a linear power output stage of comparable power rating.
Because it works with almost no heatsink and no bulky banks of output devices and uses half the power because very little is wasted... It can be made small and light weight and has half the power supply requirements...

One of my prototypes was doing 100-120V bass on 2 ohms for almost 5 hours last saturday night. Heatsink never got more than 22C over ambient. 50W THD is .00x (below my measurement capabilities). You could call it 50W hi-fi with a *lot* of headroom it's not really much bigger than 50W class AB.
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Old 29th April 2009, 06:58 PM   #53
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There's a bonus of tracking power supply system. Output transistor works in near constant Vce. Like LabGruppen or Yamaha YST-SW800 system.
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Old 30th April 2009, 02:56 AM   #54
GK is offline GK  Australia
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Quote:
Originally posted by Eva
Because it works with almost no heatsink and no bulky banks of output devices and uses half the power because very little is wasted... It can be made small and light weight and has half the power supply requirements...

Who was arguing about efficiency? I was under the impression that class D was setting new, unmatched standards in linearity

I'd like to see the "no significant non-linearity" 20kHz THD Vs power plots for that Icepower amp.
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Old 30th April 2009, 04:55 AM   #55
thedawg is offline thedawg  United States
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Glen is true d amp can be as very best, immeasurable, and already this day. To saying could be better than amp of same caliber of other class, more efficient yes, otherwise equivalent, still with all having own problem set per class, unless selling me something then all gravy.

Still saying you not so wrong, so if true other can no be 100% anything. You least keeping more point and you not even d guy. Problemm you seeing in discusting is opponent here for sale. Almost every post in almost every thread as record with worn line my new prototype my new prototype my new prototype, no can see but can buy, my new prototype call me. Someone saying new prototype? Who having new prototype? Thought heard something for new prototype somewhere.. no can remembering where.
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Old 30th April 2009, 05:18 AM   #56
Eva is offline Eva  Spain
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Quote:
Originally posted by G.Kleinschmidt


Who was arguing about efficiency? I was under the impression that class D was setting new, unmatched standards in linearity

It's not setting new standards, it's coming closer and closer to the existing ones probably to the extent of replacing linear amplifiers because the smaller and smaller linearity improvement is no longer worth the expense.
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Old 30th April 2009, 05:39 AM   #57
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Quote:
Originally posted by thedawg
Glen is true d amp can be as very best, immeasurable, and already this day. To saying could be better than amp of same caliber of other class, more efficient yes, otherwise equivalent, still with all having own problem set per class, unless selling me something then all gravy.

Still saying you not so wrong, so if true other can no be 100% anything. You least keeping more point and you not even d guy. Problemm you seeing in discusting is opponent here for sale. Almost every post in almost every thread as record with worn line my new prototype my new prototype my new prototype, no can see but can buy, my new prototype call me. Someone saying new prototype? Who having new prototype? Thought heard something for new prototype somewhere.. no can remembering where.

Well said.
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Old 30th April 2009, 03:38 PM   #58
TOINO is offline TOINO  Portugal
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I am not sure that the way used nowadays to measure THD in class-D amplifiers is fair.
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Old 30th April 2009, 05:39 PM   #59
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Glenn,

I've done some extensive reading and also consulted a friend of mine who is a succesfull high-end audio designer on the issues regarding class D and class A amplifiers (not necessarily a combination of these two!).

I have decided to go for class A and Andy C has kindly sent me the AES papers you mentioned earlier.

Once more thanks for your valuable input.
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