Common Source versus Common Drain output stages - Page 4

Tube_Dude · 5th July 2002, 11:02 PM

Yes Sonny but what about the EMF from the Speker??

Jorge

sonnya · 5th July 2002, 11:18 PM

In common collector/emitter one of you Transistor will turn of and create switch glitches.

Both circuits will have the same control over the speaker when they have the same output impedance, frequency response and phase margin..

Only then you wil be able to compare those two types of output stages.

Sonny

AMPMAN · 6th July 2002, 03:22 AM

I quote cordell directly, Interface intermodulation was next measured in a manner equivalent to the procedure outlined in reference 1. Equal-level 1000 and 60Hz signals were applied to opposite ends of an 8 ohm load resistor by the amplifier under test and a second power amplifier. A spectrum analyzer was placed across the output of the amplifier under test and the R.M.S. sum of the distortion products was referred to the 1kHz level. The operating level of each amplifier was 25W. The similar levels of interface intermodulation in all 3 cases confirm that open-loop output impedence and feedback factor have virtually nothing to do with it in amplifiers properly constructed at the same cost.
This is the summary of a highly detailed and exhaustive analysis investigating interface intermodulation by an expert in this field.

Samuel Jayaraj · 27th March 2003, 02:04 PM

Ampman,

Have you actually built the circuit (of the schematic posted in this thread) from EW&WW using 2SC5200 and 2SA1943 transistors? How does this amp sound?

As a starting point, I built this amp soon after publication of the article and since the output devices were not available(even then), I used MJE3055/2955 transistors. Soon after powering up, the bias shot up and blew the output devices. Although I had to hand, quite a large number of 2SC3281 and 2SA1302 transistors, I did not try the amp with these. I thought that the 60MHz fT criteria was quite critical to the stability of the design while the transistors I had were only about 30MHz, and gave up completely on the design.

Input from your success may cause me to give this amp a try again. Thanks.

6th July 2002, 03:22 AM	#33
AMPMAN diyAudio Member Join Date: May 2002 Location: toronto canada	tube dude I quote cordell directly, Interface intermodulation was next measured in a manner equivalent to the procedure outlined in reference 1. Equal-level 1000 and 60Hz signals were applied to opposite ends of an 8 ohm load resistor by the amplifier under test and a second power amplifier. A spectrum analyzer was placed across the output of the amplifier under test and the R.M.S. sum of the distortion products was referred to the 1kHz level. The operating level of each amplifier was 25W. The similar levels of interface intermodulation in all 3 cases confirm that open-loop output impedence and feedback factor have virtually nothing to do with it in amplifiers properly constructed at the same cost. This is the summary of a highly detailed and exhaustive analysis investigating interface intermodulation by an expert in this field. __________________ RW

27th March 2003, 02:04 PM	#34
Samuel Jayaraj diyAudio Member Join Date: May 2001 Location: Bangalore, India	Ampman, Have you actually built the circuit (of the schematic posted in this thread) from EW&WW using 2SC5200 and 2SA1943 transistors? How does this amp sound? As a starting point, I built this amp soon after publication of the article and since the output devices were not available(even then), I used MJE3055/2955 transistors. Soon after powering up, the bias shot up and blew the output devices. Although I had to hand, quite a large number of 2SC3281 and 2SA1302 transistors, I did not try the amp with these. I thought that the 60MHz fT criteria was quite critical to the stability of the design while the transistors I had were only about 30MHz, and gave up completely on the design. Input from your success may cause me to give this amp a try again. Thanks. __________________ Sam

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5th July 2002, 11:02 PM	#31
Tube_Dude diyAudio Member Join Date: Mar 2002 Location: Aveiro-Portugal	Yes Sonny but what about the EMF from the Speker?? Jorge

5th July 2002, 11:18 PM	#32
sonnya diyAudio Member Join Date: Oct 2001 Location: Denmark	In common collector/emitter one of you Transistor will turn of and create switch glitches. Both circuits will have the same control over the speaker when they have the same output impedance, frequency response and phase margin.. Only then you wil be able to compare those two types of output stages. Sonny

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