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Old 27th August 2010, 01:17 PM   #21
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AndrewT,

his protection circuit removes the drive before the "VAS". It's not of the usual type that shorts out the drive to the output stage after it.
 
Old 27th August 2010, 01:32 PM   #22
DjLeco is offline DjLeco  Romania
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Quote:
Originally Posted by megajocke View Post
AndrewT,

his protection circuit removes the drive before the "VAS". It's not of the usual type that shorts out the drive to the output stage after it.
Perfectly observed!
 
Old 27th August 2010, 02:34 PM   #23
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@DjLeco, diagram overload protection I think like with the diagram below called amp.jpg (I could even say almost the entire amplifier, perhaps with some small differences, the number of output transistors...).

I have attached below block diagram drawn by you where I framed with red some resistors. What value are the currents through those resistors?

I ask this because that current values are important for proper functioning of the amplifier. DC balance of the input differential pair is essential in power amplifiers. It still seems almost unknown that minor deviations from equal Ic in the pair seriously upset the second-harmonic cancellation. So, imbalance also reduces the open-loop gain if serious enough. Treat this issue very carefully.

Regards.
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Last edited by Salas; 28th August 2010 at 12:13 AM. Reason: asked by the poster
 
Old 27th August 2010, 02:45 PM   #24
DjLeco is offline DjLeco  Romania
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Donpetru,checkPM.
 
Old 27th August 2010, 04:44 PM   #25
DjLeco is offline DjLeco  Romania
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Please someone calculate aproximative Damping Factor

www.youtube.com/watch?v=24pfrHL93qk

www.youtube.com/watch?v=9VBFspvUOv4

www.youtube.com/watch?v=eabMHBY4mEo

Damping on speakers:

www.youtube.com/watch?v=pv2LQuZOVbQ


Nice movie!

www.youtube.com/watch?v=PsJER9dxxGc

Last edited by DjLeco; 27th August 2010 at 04:47 PM.
 
Old 28th August 2010, 08:37 AM   #26
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If you want to calculate practical the damping factor, follow instructions from there (they is not pretty accurate but... works!):
Damping Factor with Calculator

On the other hand, damping factor is of two types:

1. Rated Damping Factor = RDF (as shown in the calculation of the site posted above). This damping factor is calculated based on laboratory test conditions which have little connection with actual operation of the amplifier.

2. Effective Damping Factor = EFD (more accurately describes the interaction between a real amplifier and a real speaker). So, when we calculate the EDF of an amplifier, it is absolutely necessary that we include this DC resistance into the damping factor expression. For example, if the actual impedance of the speaker may be 4 Ohms and we measure the voice coil of this speaker, we will probably find that it has a DC resistance of about 3 Ohms. Then, there must be taken into account the impedance of the speaker resonance (which can reach and the 40 ohm). We need to take account of this, because at resonance, speakers typically are very uncontrolled and have the least mechanical damping. So this is damping factor, I tell you... is real (and usually is much smaller than RFD).

Later edit: Remember that all, any amount of damping factor is affected by power supply amplifier characteristics. Design well the power supply to have a high damping factor.

Regards.
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Last edited by donpetru; 28th August 2010 at 08:43 AM.
 
Old 28th August 2010, 08:49 AM   #27
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I konow that link with DF calculator.

And yes a speaker with impedance of 4 ohms, have coil resistance(in ohms) between 3,2 and 3,8 ohms, but it varies alot at resonance freq of speaker...
 
Old 4th September 2010, 05:01 AM   #28
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hello DjLeco,..i'm interest to build this power designt from you please share the schematic and list of component to my email hadita_adit@ymail.com)

thanks
 
Old 4th September 2010, 07:03 AM   #29
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Why all this movie stuff ?? Just post the schematic.
Just a full complimentary topology (another one), would just be interested in how YOU do it , add knowledge to all the other versions ?

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Old 4th September 2010, 10:01 AM   #30
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It's a full complementary design, perfectly simmetric.

Sorry for not sharing schematic, that is MY prototype, I go from a simple schematic, developed till here.
 

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