Vunce, please have a look here, its beefed up version of this little pre. Runs hot, output bjt needs small heatsink, but it sounds phenomenally good. When used as headphone amp, or pre.
Post in thread 'DIY Class A Headphone Amp suggestion' https://www.diyaudio.com/community/threads/diy-class-a-headphone-amp-suggestion.415623/post-7754502
Post in thread 'DIY Class A Headphone Amp suggestion' https://www.diyaudio.com/community/threads/diy-class-a-headphone-amp-suggestion.415623/post-7754502
Thanks Adason.
But, you might not believe this, I don’t use headphones at all so no use for an HPA.
I’d have to look into the changes needed for dedicated preamp duty.
Jack of all trades is master of none 🤣.
But, you might not believe this, I don’t use headphones at all so no use for an HPA.
I’d have to look into the changes needed for dedicated preamp duty.
Jack of all trades is master of none 🤣.
These principle of circuits might be of interest as a MC stepup.
Low powered, low but linear distortion in both active stages and a Zout low enough to easily drive 47kohm and usual capacitive load.
High feedback reduce noise pickup. High Zin.
Low powered, low but linear distortion in both active stages and a Zout low enough to easily drive 47kohm and usual capacitive load.
High feedback reduce noise pickup. High Zin.
https://www.elektormagazine.nl/magazine/elektor-197999/42826
The original is in the Journal of the Audio Engineering Society April 1980.
The original is in the Journal of the Audio Engineering Society April 1980.
"High feedback reduce noise pickup. High Zin."
Very questionable statements. About half of MC carts are happy to work into 0ohm loads and max load resistance does not exceed 1k. One place with really no need for NFB is the MC stepup.
@analog_sa
I understand why you think so since I didn't told the full concept, but high linear impedance from the circuit input is what you want to be able to have a pure resistive load on the cartridge when loading it with recommended resistor. The circuit itself should load the cartridge as little as possible.
I think it is of interest since Zin of the circuit is high enough to compete with a jfet, but with the potential to pick up less noise.
Will test it in my system in the future and see how it performs.
I understand why you think so since I didn't told the full concept, but high linear impedance from the circuit input is what you want to be able to have a pure resistive load on the cartridge when loading it with recommended resistor. The circuit itself should load the cartridge as little as possible.
I think it is of interest since Zin of the circuit is high enough to compete with a jfet, but with the potential to pick up less noise.
Will test it in my system in the future and see how it performs.
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Yes, very likely. But sometimes you can select very low noise jfet. Out of few hundred there is few.
I personally use ortofon and audiotechnica step up transformers.
I personally use ortofon and audiotechnica step up transformers.
But since i do have complementary pair 2n4401/2n4403, i will make eventually common base circuit. Just out of curiosity. But not now, too many other projects unfinished.
With a high-transconductance JFET, the grid stopper and feedback network will dominate the noise of post #49.
Gents, I have a question about some residual spikes on my THD measurement.
I was using nuforce very simple dac with focusrite scarlet as adc. Noise floor and distortion of nuforce was not that good.
I replaced it with shiit modi and just got topping e30 II, as it was cheap and recommended.
THD dropped, as expected, 0.0015% and 0.0028% respectively, but i see some spikes at 8kHz and 16kHz.
I was using nuforce very simple dac with focusrite scarlet as adc. Noise floor and distortion of nuforce was not that good.
I replaced it with shiit modi and just got topping e30 II, as it was cheap and recommended.
THD dropped, as expected, 0.0015% and 0.0028% respectively, but i see some spikes at 8kHz and 16kHz.
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However, these two spikes at 8kHz and 16kHz are not harmonics from 1kHz fundamental. They are present all the time even without 1kHz sine signal, as you can see from noise floor measurements.
They are there even at intermodulation measurent (60Hz plus 7kHz).
Any idea where are spikes comming from and how to get rid of it?
They are there even at intermodulation measurent (60Hz plus 7kHz).
Any idea where are spikes comming from and how to get rid of it?
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The usual debugging approach is to turn off all equipment you can turn off to see if that helps. If it does, you can turn on half the equipment again and do a binary search, or simply turn things on one by one. If the anti-aliasing filter of the ADC is imperfect, which it always is, a strong interference at some high frequency can also look like a small interference at an audio frequency.