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.
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.
Needs a follower driving that Baxandall. What’s two more 7 cent transistors anyway? And then you’re going to want a mag phono stage, right? Before you know it the BOM cost will go up another whole dollar.
Nothin’ special about those transistors. Use whatever you yank out of an old junk stereo - as long as they are not 2SC458’s.
Nothin’ special about those transistors. Use whatever you yank out of an old junk stereo - as long as they are not 2SC458’s.
Ask yourself what the real differences between the BC54x and 55x series are. I’m sure the reason that 547 was used is “because I have a model for it, and it’s NPN”.
The reason I chose the BC547 was because of my own large stock. They also have the benefit of being very available and very cheap. But like wg_ski said any general purpose small signal transistor will work.
Have some BC547B's in stock. Will try first linestage with those. Close enough.
Edit: I have a phonostage, but maybe someone other needs also this.
What is needed is a PCB design ...
Edit: I have a phonostage, but maybe someone other needs also this.
What is needed is a PCB design ...
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Those will work, they just have less gain as you probably already know. I was thinking about temperature compensation, would it be smart to glue the diode to the output driver? In simulation the bias current changes a few mA with temperature change ( 0 to 100°C). I don't think it's anything to worry about, but if a little glue improves things, why not then?
This is also a simple preamp.
Gain=3 and low distortion.
Gain=3 and low distortion.
Yes, measured Hfe is around 100 or little bit more. Those C grade are factory selected to have more Hfe. Can glue diode to driver transistor. As discussed before almost any NPN should be ok.
I made a typo in my last post. I meant if it would be wise to glue the diode to the output transistor. Not the driver (which is also the input stage🙂).
Anyway it was more of a question than a suggestion. Hope it works 🤞
Anyway it was more of a question than a suggestion. Hope it works 🤞
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/
Sweet tube like sounding pre is Hamptone.