Transistor Preamp

[PRR]

It is ok for a low fi application such as boasting an cell phone output.

R1 makes NO sense unless it is for an electret capsule (naked or in a headset).

At moderate speech levels, a few mV, the THD will be acceptable.

In a hi-fi system, the juice coming out of R1 may annoy the source, and hundreds of mV signal will make it a "fuzz box".

 

[cumbb]

Most time we do not need any "pre-amp", may be;-)
Leave it, unless you want to do disco or be the loudest in the village;-)

 

[Bigun]

One reason I can think of for wanting an active pre-amp is to use a circuit that makes a linear pot behave like a log pot. Linear pots are known to have far better ch-ch tracking. The only example I'm aware of is the Shindo Claret all-tube pre-amp but I'm sure there are SS examples.

 

[Mark Johnson]

The Self preamp in Linear Audio uses the "Baxandall Volume Control" circuit which includes a linear (not logarithmic) potentiometer. If you download the documentation from this page , you can see the full schematic.

_

 

[Mark Tillotson]

That circuit is designed for low source impedances only, and I believe doesn't go to fully mute.

 

[Gnobuddy]

That circuit is designed for low source impedances only, and I believe doesn't go to fully mute.

I agree about the low input impedance. It does look to me as though voltage gain goes to nominally zero, though, when the pot is fully CCW. That setting results in a nominally zero-ohms feedback resistor from output to inverting input.


-Gnobuddy

 

[Mark Tillotson]

5 ohms output impedance though, rather the sub-ohm you'd get with a single opamp output amp. That allows a small voltage to be injected at -60dB or so.


Rather than parallel that opamp, its output should have been augmented after the feedback point.

 

[Gurpreet Turna]

Hello Bimo(Anistardi) and Diy members, I need Gerber file of this simple blameless Pre-amp. If somebody have please Post.
Regards

 

[bimo]

Hello Bimo(Anistardi) and Diy members, I need Gerber file of this simple blameless Pre-amp. If somebody have please Post.
Regards

https://www.diyaudio.com/forums/analog-line-level/296144-transistor-preamp-19.html#post4826846

 

[Gurpreet Turna]

Thanks Bimo for replying.

 

[naadbrahma]

Thanks Bimo for replying.

Hello You got Gerber for Blameless Preamplifier ?

 

[kardee]

Any good small, easy, high fidelity transistorised preamplifier circuit that i can build ? Plan to use it with my DIY power amp. The preamp should be able to accept ipod level input.

Any help would be appreciated.

Just for Jrp27=late memory rewind, Plz, refer to Andy Collinson's & Graham Maynard's hi fi pre-amplifier circuit _ link= http://www.zen22142.zen.co.uk/Circuits/Audio/hifipreamp.htm.
2sd30, obsolete unobtainium Japanese metal transistor hyped (net) to be single transistor audiophile preamp?

 

[VIPINSAINI20]

Hello Bimo(Anistardi) and Diy members, I need Gerber file of this simple blameless Pre-amp. If somebody have please Post.
Regards

Did you get those Gerber files,
If you got them can you share them here with us

 

[tavares_costa]

I like Apex designs - they are easy to make, work, and sound good.

BJT:

FET:

More here:
http://www.diyaudio.com/forums/solid-state/164093-100w-ultimate-fidelity-amplifier-6.html

Very neat design.
Congratulations to @apexaudio

 

[tavares_costa]

James Bongiorno is the designer of Ampzilla and other famous products.

Here is an article he wrote for the June 1972 issue of Popular Electronics, with the modest title

Build a Distortionless Preamplifier

Oops since it is bigger than the max filesize for .pdf here on DIYA, I have extracted each page of the article individually. There are 5 pages and 5 .pdf files attached. Sorry for the annoyance.

Impressive for a 70's Preamp

 

[Extreme_Boky]

Very neat design.
Congratulations to @apexaudio

Nothing in the signal path... pretty good eh??? Just 2 gain devices. If I ever become cruel & senseless to insert a preamp in my setup, this will be it.