A simple discrete one-watt amplifier

[lineup]

That's a good one.

Similar to beefed up headphone pre I suggested.

Other option for simple descrete pre with jfet is here.
https://blog.audioworkshop.org/simple-jfet-preamp/

That is a good option.
With JFET it is almost like my suggestion.

 

[njswede]

I made this little 6 transistor pre-amp in Tina-Ti.
It's just a simulation for now, and I hope to get feedback on it.
I added the schematic and some (simulated) measurements.
It consists of a Baxandall tone control and a gain stage with a voltage gain of about 3 (9.5dB).
THD is 0.014% at 1kHz and 0.08% at 10kHz. This is with 2.16Vrms out, into a 1kohm load.

View attachment 1424306
View attachment 1424308
View attachment 1424309

I love the bog standard component choices. Might be a good companion to my Bog Standard power amplifier!

 

[lineup]

This is the JFET input version of my preamp.
Gain is ~3.5

 

[No ideas]

This is also a simple preamp.
Gain=3 and low distortion.

View attachment 1424686

3 times the input signal or 3db?

 

[No ideas]

This is also a simple preamp.
Gain=3 and low distortion.

View attachment 1424686

What if we runned everything at 15V?

 

[No ideas]

This is the JFET input version of my preamp.
Gain is ~3.5

View attachment 1424737

The only thing i lack is the 390ohm.
Or i dont know where i placed it.

 

[xa488]

I love the bog standard component choices. Might be a good companion to my Bog Standard power amplifier!

I'm hoping to find some time to actually build it. I can report back afterwards on the technicalities.

But I think your power amplifier is a few leagues higher than this simplistic pre-amp. I designed it to compliment the simplistic one watt amplifier that started this thread. But if it sounds good, why not 🙂.

 

[HJH]

Here used BC548B with 1N4001, needs say 24h waiting time, this glue isn't quick ... those 'bog-standard' 2N5xxx should work as well.

 

[wg_ski]

How much force do you need to hold them together? You can find something that sets in minutes, not hours.

 

[lineup]

This is a good preamplifier.
It uses J113 JFET which should be easier to find and buy than BF245B.
Gain is now ~5.5
Distortion is very low!

 

[No ideas]

i happen to have the bf245 jfet, i would also include an 100pF capacitor parallel to the 1Meg input resistor

 

[No ideas]

This is a good preamplifier.
It uses J113 JFET which should be easier to find and buy than BF245B.
Gain is now ~5.5
Distortion is very low!

View attachment 1424816

Could i connect a high value volume pot directly to the output of the amplifier without the double capacitors?

 

[Rwan]

This is a good preamplifier.
It uses J113 JFET which should be easier to find and buy than BF245B.
Gain is now ~5.5
Distortion is very low!

View attachment 1424816

How about increase power like 1 or 2 watt same like this but with 2 or more BJT output Class A or like Jlh1969 single Jfet input? 🤔 Has anyone tried?? 🤔

 

[Rwan]

Like this one

 

[HJH]

How much force do you need to hold them together? You can find something that sets in minutes, not hours.

This glue works well but needs time, not force, only waiting. Cyanoacrylate glue should work also, not tested.

 

[wg_ski]

Longer-setting epoxies tend to be stronger, and that extra strength isn’t needed. Just get the 5 minute stuff.

 

[HJH]

This is used because "I have it and it works" , again an overkill solution 😃

 

[No ideas]

I found this intresting dead simple headphone amp schematic, i also simulated it and it can do up to 2V rms.

 

[No ideas]

This is the JFET input version of my preamp.
Gain is ~3.5

View attachment 1424737

seems like R2 sets gain.

 

[lineup]

Gain is like R1/R2+1
Most cases there is not any need for an input capacitor.
R5 does not need to be 1M. It could even be 100k.