# Amplificador 65W HEXFET



## juanma (Feb 13, 2008)

Aca les dejo los datos de este amplificador con la fuente incluida
Hay muchisimos mas buscando un google... solo puse este, pero el que busca encuentra...

Tambien les dejo lo que decia la pagina:

Adjustment:
A medium power amplificadorfier   that is characterized by a lot of good sound quality, but simultaneously is very simple in the construction. Him uses, enough time in my active loudspeakers. In his output stage exist the very good FET transistors, technology HEXFET, transistor which are controlled by voltage and no by current as the classically bipolar transistors. The circuit has symmetrical designing, resolving thus the harmonic distortion problem. All the transistors that are used in the circuit are simple and they exist in big clearings in the market. The pairs of differential amplificadorfiers Q1-2 and Q3-4 should be matched between them and near the one in the other. Thus you can buy enough transistors of types BC550C and BC560C, and with a multimeter you match between them creating pairs with same characteristics, ensuring thus uniform behavior in the temperature changes etc. Networks RC from the R7/C3 and R12/C4 decrease the bandwidth of differential amplificadorfiers and power amplificadorfier in the 6.5MHZ. Resistors R8-9-10-11 function as local feedback in the differential amplificadorfiers improving the linearity. The differential amplificadorfiers are supplied with constant current from him current sources Q5 and Q6. The bias of current sources becomes from the combination of diodes LED D1, D2 and R20. This becomes because the combination transistor/LED ensures big thermic stability, for this reason should they are in very near distance [1]. With the TR1 trimmer we regulate the bias current of output power stage. For this reason Q8 should find itself on the heatsink so that it ensures thermic stability in the bias, so that it does not change with the temperature changes. The resistors R32-33 shape a local feedback bronchus in the output stage, because this functions as voltage amplificadorfier. With the TR1, R3-4, C14 we regulate the amplificadorfier output DC offset voltage, near in the zero. The transistors Q8-10-11-12-13,  [Fig.1] should are placed on heatsink, adding between the transistors and the heatsink of good quality leaves mica and ointment. Inductor L1 is constituted by 6 coils of insulated cupreous wire of diameter 1.5mm, with internal inductor diameter of 16mm [2]. 

Adjustment
  Previous to we supply the amplificadorfier with voltage, we regulate the trimmer TR2 in the mid of his way and the trimmer TR1 in biggest resistance. We connect a multimeter in output pin J4 (measurement range 200mV DC), we give voltage in the amplificadorfier and with the TR2 we regulate so that we take DC voltage in the output as possible near in the zero. We remove the supply and connect a multimeter (range 1A or 2A) in line with one from the supply cables. We again give supply in the amplificadorfier and with the TR1 regulate late the current, so that we take clue roughly 330mA. We leave the amplificadorfier to work for 10 min., without audio signal in his input. Afterwards the 10-min. usually the current stabilized in 230mA roughly. If it needs we adjust late so that we take clue near in 230mA. We again check the amplificadorfier DC offset [J4] output, for changes DC and if it needs we regulate again with the TR2. [Elektor12/93]. 

Power Supply:
A medium power amplificadorfier   that is characterized by a lot of good sound quality, but simultaneously is very simple in the construction. Him uses, enough time in my active loudspeakers. In his output stage exist the very good FET transistors, technology HEXFET, transistor which are controlled by voltage and no by current as the classically bipolar transistors. The circuit has symmetrical designing, resolving thus the harmonic distortion problem. All the transistors that are used in the circuit are simple and they exist in big clearings in the market. The pairs of differential amplificadorfiers Q1-2 and Q3-4 should be matched between them and near the one in the other. Thus you can buy enough transistors of types BC550C and BC560C, and with a multimeter you match between them creating pairs with same characteristics, ensuring thus uniform behavior in the temperature changes etc. Networks RC from the R7/C3 and R12/C4 decrease the bandwidth of differential amplificadorfiers and power amplificadorfier in the 6.5MHZ. Resistors R8-9-10-11 function as local feedback in the differential amplificadorfiers improving the linearity. The differential amplificadorfiers are supplied with constant current from him current sources Q5 and Q6. The bias of current sources becomes from the combination of diodes LED D1, D2 and R20. This becomes because the combination transistor/LED ensures big thermic stability, for this reason should they are in very near distance [1]. With the TR1 trimmer we regulate the bias current of output power stage. For this reason Q8 should find itself on the heatsink so that it ensures thermic stability in the bias, so that it does not change with the temperature changes. The resistors R32-33 shape a local feedback bronchus in the output stage, because this functions as voltage amplificadorfier. With the TR1, R3-4, C14 we regulate the amplificadorfier output DC offset voltage, near in the zero. The transistors Q8-10-11-12-13,  [Fig.1] should are placed on heatsink, adding between the transistors and the heatsink of good quality leaves mica and ointment. Inductor L1 is constituted by 6 coils of insulated cupreous wire of diameter 1.5mm, with internal inductor diameter of 16mm [2]. 

Adjustment

  Previous to we supply the amplificadorfier with voltage, we regulate the trimmer TR2 in the mid of his way and the trimmer TR1 in biggest resistance. We connect a multimeter in output pin J4 (measurement range 200mV DC), we give voltage in the amplificadorfier and with the TR2 we regulate so that we take DC voltage in the output as possible near in the zero. We remove the supply and connect a multimeter (range 1A or 2A) in line with one from the supply cables. We again give supply in the amplificadorfier and with the TR1 regulate late the current, so that we take clue roughly 330mA. We leave the amplificadorfier to work for 10 min., without audio signal in his input. Afterwards the 10-min. usually the current stabilized in 230mA roughly. If it needs we adjust late so that we take clue near in 230mA. We again check the amplificadorfier DC offset [J4] output, for changes DC and if it needs we regulate again with the TR2. [Elektor12/93].


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## juanma (Feb 13, 2008)

Aca el resto:

Bueno, saludos y espero opiniones


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## lucalorito (Ene 15, 2009)

Subo este tema por que me parece interesante el diseño..
http://users.otenet.gr/~ATHSAM/power_amplificadorfier_65w_hexfet_eng.htm
¿ Lo podríamos considerar como hi-end? Me gustaría que diéseis vuestra opinión sobre él y de paso si alguien lo ha montado que dé sus opiniones de escucha.
Saludos


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## Fogonazo (Ene 15, 2009)

lucalorito dijo:
			
		

> Subo este tema por que me parece interesante el diseño..
> http://users.otenet.gr/~ATHSAM/power_amplificadorfier_65w_hexfet_eng.htm   ......


Ese esquema se parece un tanto a este otro, *mas bien diria que es el mismo*
https://www.forosdeelectronica.com/download.php?id=8139

Y que casulamente esta en este mismo post ¿?¿?¿?¿?


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## lucalorito (Ene 15, 2009)

Es que es del que estoy hablando..lo que pasa es que puse el link en donde se describe el mismo..fogonazo que te parece el bicho.
Saludos.


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## Elvis! (Ene 15, 2009)

Jaja muy bueno Lucalorito!
Una pregunta cuando se considera que un amplificador es Hi-End?


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## lucalorito (Ene 15, 2009)

Cuando suena muy bien!


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## Cacho (Ene 15, 2009)

Elvis! dijo:
			
		

> Una pregunta cuando se considera que un amplificador es Hi-End?



Yo pregunté lo mismo...
Hasta donde llegué a entender, un Hi-End tiene:
* niveles bajos de distorsión, del orden de 0,00X% (aunque los valvulares son la comprensible excepción).
* un gabinete y presentación elaboradas que te dejan muy bien impresionado.
* en la electrónica suelen ser más complejos.
* un costo alto o altísimo, dependiendo del fabricante.

A mi criterio, como hoy en día casi todos los equipos están cerca de esas especificaciones de distorsión (sin las complejidades de los Hi-End), Hi-End quiere decir gran presentación y mayor precio.
He llegado a ver la calificación de Hi-End en amplificadores hechos con el LM3886 y sus parientes, pero con un gran diseño de gabinete. Y eran carísimos.
Qué sé yo... A esta altura ya asocio Hi-End con "5000W PMPO": Nadie sabe cómo se mide (qué parámetro se usa) y hace que el precio se vaya a las nubes.

Honestamente espero estar equivocado y que alguien me corrija.

Saludos


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## lucalorito (Ene 17, 2009)

Tienes razón en todos esos planteamientos...es cierto que una buena presentación del diseño puede llegar a sugestionar hasta el punto de que un amplificador barato de diseño nos suena mejor que otro mucho más caro..pero claro, el hi-end yo entiendo que es la suma de un buen chasis, buen diseño electrónico, fuente de alimentación competente, etc, etc, todo esto es dinero y eso nos lleva al hi-end.


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## lucalorito (Ene 20, 2009)

Por cierto que lo estoy montando..en cuanto lo termine os cuento mis impresiones sobre estos hexfet..por el momento armé etapas con mos-fet, darlington, y bipolares..sólo me faltan estos y los dichosos igbt que se han esfumado del planeta..


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## Elvis! (Ene 20, 2009)

Entonces lo que se entiende es que si agarro el peor de los transistores y le mando sonido siempre y cuando este dentro de una obra maestra en chasis ya puedo cobrarle lo que se me ocurra por que?..Porque es Hi-End!
Me quedo con mis placas virgenes!


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## Cacho (Ene 20, 2009)

Y... A mi criterio, Elvis, no estás demasiado lejos de la verdad. Sólo necesitás buena propaganda y que no suene horrible.

Lucalorito, entrá a las páginas de los fabricantes (Fairchild, OnSemi, Mospec, Texas, etc) y fijate si siguen produciendo los IGBTs que buscás. Si no están fabricándose (ni uno que los reemplace) te las vas a ver difíciles para conseguirlos.

Saludos


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