Transistor Preamp

[xrk971]

Why don't they just make a class A opamp IC with that current sink in place already? External heatsink may be required. No one likes a heatsink on a 8pin DIP.

 

[Joachim Gerhard]

You get really low distortion if you use the NE5534 inverted and 8mA CCS to the POSITIVE supply. To have then a high input impedance you need a Buffer. That can be a compensated NE5534. I use that in a headphone amp i designed and nobody is complaining.
The output of the headphone amp is a modified Diamond buffer.

 

[Joachim Gerhard]

This circuit gave great results. I used NE5532 so compensation is not nessessary. It can be used as a preamp too. The CFB pair gives particualr low distortion with low impedance. I optimised that circuit for my Audeze LX headphone.

 

[apexaudio]

That is Apex Audio's work - I just re-posted. I asked him in his thread if pcb files are available. He will let us know if he has pcb files. I am looking for a good preamp as well.

http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-858.html#post4817973

I suggest SR PP12 preamp from thread: http://www.diyaudio.com/forums/solid-state/173462-studio-reference-amplifier-180.html

 

[ammel68]

I suggest SR PP12 preamp from thread: http://www.diyaudio.com/forums/solid-state/173462-studio-reference-amplifier-180.html

A big n' nasty 220uF coupling cap on the output?

Can the offset not be controlled with a trimmer(s) somewhere in the circuit or with a servo?

 

[Bigun]

The old superstitions are alive and kicking

.... I'm finding increasingly that capacitors done right, in the signal path, are a non-issue. On the output between amp and speaker is a bit different but there are options.

 

[ammel68]

The old superstitions are alive and kicking

No superstitions...I avoid them when I can, especially a capacitor that size which would obviously have to be an electrolytic.

 

[xrk971]

Bypass with a good 3.3uF film and no one knows the difference.

 

[Bigun]

I really like modern electrolytics, they're small in size, nice and shiny and sound just fine to me - especially those audio bipolar types... In fact these days I use electrolytics where I can and my amps sound super good judging by what others have to say about them. Strangely, I don't use film caps much, bulky, awkward and the pricing of them make me laugh ! For small caps you can't go wrong with a quality C0G.

 

[brucetassin]

The OP asked for transistor preamp, lets give him what he wants.
I built this one also and the results are very good.

A Simple, HIGH QUALITY Transistor Preamp

 

[vzaichenko]

The OP asked for transistor preamp, lets give him what he wants.
I built this one also and the results are very good.

A Simple, HIGH QUALITY Transistor Preamp

Very high gain again, designed for the Mic / Phono stage.
The OP is asking for a line stage with 4-6 db gain.
A number of good options is already presented.

 

[kroto]

Not Been Build Yet

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.

Not been built yet, but should operate well.

Discrete transistor, Class-A (12mA), Current feedback, gain of 6dB.
Fast & low THD (0.0043% @ 20kHz; 2Vpk; RL 10k; CL 500p)

 

[gannaji]

This circuit is simple and suitable !

 

[xrk971]

Nice design Kroto. Are there any alternatives to the BC337?

 

[ammel68]

This circuit is simple and suitable !

Part numbers for the transistors and operating voltage??

 

[Jrp27]

The OP asked for transistor preamp, lets give him what he wants.
I built this one also and the results are very good.

A Simple, HIGH QUALITY Transistor Preamp

Thank you.I saw the schematic and it has ceramic pickup and magnetic pickup. How can I modify it to work on ipod level input?

 

[Karl vd Berg]

SR PP12 preamp

A big n' nasty 220uF coupling cap on the output?

Can the offset not be controlled with a trimmer(s) somewhere in the circuit or with a servo?

Harman Kardon used generic 220uF/25V TK caps in some preamp section in a few 1990s integrated. When replaced with quality caps like MUSE, Os-Con or polymer the results were very, very good and hard to distinguish...

The idea of a trimmer for the offset is interesting.

 

[JMFahey]

Ok, I guess our Friend jrp27 just earned a custom design

with lots of jugaad, of course

I don´t want to even *imagine* what kind of chassis it might be housed in

 

[Mark Johnson]

Are there any alternatives to the BC337?

It's a good performing & well behaved transistor, first image below. I bought 200 of them (total cost: $13.50) from Mouser: sales link

_

 

[Project16]

The site is in French but here you have 9 preamplifiers transistors with different gains. With an online translator you should get out.
schémas simples de préamplificateurs BF à transistors ~ Schemas Montages realisation Electronique