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Bonsai 11th February 2011 11:38 AM

class A Line level buffer
Hi, I've just posted a class A line level buffer design up on my website.

Also just added is an article on RIAA Equalizers.


Ken Newton 11th February 2011 01:42 PM


As far as I'm concerned, you win the trophy for the most professionally presented and documented diy project I can recall having ever seen. That goes for the design of your hifisonix website as well. I have some sense of the time and effort it must have taken. I'm extremely impressed.

Bonsai 11th February 2011 01:50 PM

Hi Ken - appreciate the positive comments!

PMA 11th February 2011 01:57 PM

Very nice, Bonsai. Are the plots, like FFT Figure 3, measured or a result of LTSpice?

Bonsai 11th February 2011 10:29 PM

Hello Pavel. LT Spice at this stage. This weekend I am assembling a proto on veroboard and will measure it next week on the AP at work. Article will be updated then.

Bonsai 20th February 2011 12:09 AM

Hello, I've just posted up the final article on my website below on the buffer. I was able to get some measurements done this week on the prototype I assembled last weekend. The actual measurements are now included along with minor corrections to the original article.

diegomj1973 20th February 2011 09:28 PM

1 Attachment(s)
Hola a todos!. Soy nuevo en el foro. Soy de Argentina. Vivo en Marcos Juárez, provincia de Córdoba. Quiero compartir con ustedes un diseño de circuito de mi propiedad que consiste en un power follower (drain común) capáz de desarrollar hasta 1,25W rms (por canal) sobre una carga de 6 ohmios mínimo y con niveles de distorsión más que aceptables. Dispongo de toda su especificación técnica para quien lo desée armar.

Actualmente lo utilizo conectado a la salida de un CD player (2V rms), con lo que obtengo potencias de hasta 0,66W rms sobre 6 ohmios.


PD: excuse me for my english!!!

translated by moderation

Hi everyone!. I am new to the forum. I'm from Argentina. I live in Marcos Juárez, Córdoba province. I want to share a circuit design of mine which is a power follower (common drain) capable of developing up to 1.25 W rms (per channel) with a load of 6 ohms minimum and more than acceptable distortion levels. I have all the technical specifications for those who wish to build it.

Currently I use it connected to the output of a CD player (2V rms), with which I get power of 0.66 W rms at 6 ohms.


tinitus 20th February 2011 09:38 PM

hi, diego

please post in english


AndrewT 21st February 2011 11:04 AM

just had a read through you pdf.
Well done.
It looks so simple and yet performs so well.
I'm thinking it might just be ideal as a headphone amp.
I happen to have 3 soic8 samples of the 4562
One chip and a few discretes and I'm done !

Bonsai 22nd February 2011 04:53 AM

Thank you Andrew.

I also want to measure (maybe next week) for reference an NE5532 and a TL072 in the same proto board. I susepct (and hope) the 5532 will also measure well - maybe 10-15ppm, and TL072 at maybe 20-30ppm.

My 'high end' pre-amp I am working on at the moment uses LME4900 buffers (cost a fortune . . . ). Next time round, I'll go for this buffer - less expensive, class A and performanc is not bad.

For a h/phone amp, if you use a dual op-amp, the unused part can be used to do a 2x or 3x amp to feed the buffer stage, since coming straight out of a pre-amp line stage (c. 1V RMS) you need a bit of extra gain I've found. To keep the whole thing class A, you will need to preload the first amplifer stage as well. I might draw something and put it up in the next few days - very busy at the moment.

I'd be interested to hear about your results.

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