Caught 🙂 There is in fact no push-pull power stage here. So you don't actually need complementary transistors. T3 should be able to hold the quiescent current over a longer period of time. It should not work in the linear area, because it is fixed in one operating point. I myself often use TIP32 for T3, even if T4 is TIP35 or MJ15024.
You say it is necessary with a preamp.
And this very true as the amp even has less x1 gain.
But a preamp has normally a lots of global feedback ....
With your theory it should be a preamp without global feedback.
You better design such a preamp 🙂
And this very true as the amp even has less x1 gain.
But a preamp has normally a lots of global feedback ....
With your theory it should be a preamp without global feedback.
You better design such a preamp 🙂
The voltages up to +/- 13V can be provided with an operational amplifier... with negative feedback, of course... I'm not a person of principle.
Otherwise use the same circuit as a preamplifier. Match this with 8.2 ohms as well. Now load its output with 82 ohms instead of 8.2 ohms. This way you get ten times the voltage gain.
Otherwise use the same circuit as a preamplifier. Match this with 8.2 ohms as well. Now load its output with 82 ohms instead of 8.2 ohms. This way you get ten times the voltage gain.
Have forgot meanwhile your circuit. Consider it a general recommendation.
But an SE will also benefit from identical transistors. I would even go so far as to use identical ones for all four shown. Again, preferably small ones: TO92, as already written.
It can also work that way... but around 10% THD... but above all it must be the 2nd harmonic and there are people who like it... but I would like to have a global negative feedback in this case 😉
Hello!
The current amplifier offers a particular advantage when steep fronts occur in the audio signal. The reproduction of the audio signal is highly accurate in this case. This can be seen in the simulations. Compare.
The flank:
Conclusion 1: In case of current amplifier the output voltage adjusts so that the current curve through the speaker corresponds exactly to the curve of the input signal. A voltage amplifier is far from that.
The after oscillations:
Conclusion 2: The voltage amplifier dampens the after-oscillations more quickly, but the excesses are much more violent. The current amplifier tries to counteract the after-oscillations with the output voltage in order to keep them small.
The current amplifier offers a particular advantage when steep fronts occur in the audio signal. The reproduction of the audio signal is highly accurate in this case. This can be seen in the simulations. Compare.
The flank:
Conclusion 1: In case of current amplifier the output voltage adjusts so that the current curve through the speaker corresponds exactly to the curve of the input signal. A voltage amplifier is far from that.
The after oscillations:
Conclusion 2: The voltage amplifier dampens the after-oscillations more quickly, but the excesses are much more violent. The current amplifier tries to counteract the after-oscillations with the output voltage in order to keep them small.
I've already mentioned this in another topic, but I want to expand on it here. A current audio amplifier is, in effect, a single speaker amplifier. And my amplifier is a current amplifier. This is perfect for driving the full-range speakers, because their full-range is becoming even fuller. At most, the system consisting of a guitar speaker and tweeter can be used. But here it is also the end. The crossovers ruin the sound. That's why each speaker in the systems consisting of several speakers should have its own amplifier. I personally prefer a two-way system consisting of woofer and full range driver. The tweeter is actually unnecessary.
The circuits of the amplifiers for woofer and full-range speaker differ only by one capacitor:
The circuits of the amplifiers for woofer and full-range speaker differ only by one capacitor:
Crossovers don’t “ruin” the sound. They are just not designed with high impedance amplifiers in mind. They CAN be designed to produce only a single bass peak and a gentle rise as you go up in the tweeter range, just like a single driver. Even 3-ways can be done. It’s not necessarily easy, and not all speakers are compatible with this approach - it often results in ragged frequency response with lumps and dips of its own. Speakers which require equalization in the crossover or require asymmetrical filters (electrically mismatched slopes) just aren’t good for this.
That low pass on the woofer amp may not be steep enough. If the woofer driver has an awful midrange peak it may show through. A lot of “subwoofer” drivers have this issue, intended to be crossed low and steep. Probably fine with an old school 12”, but those just arent popular anymore (Requiring too large a box for moderate output at best).
That low pass on the woofer amp may not be steep enough. If the woofer driver has an awful midrange peak it may show through. A lot of “subwoofer” drivers have this issue, intended to be crossed low and steep. Probably fine with an old school 12”, but those just arent popular anymore (Requiring too large a box for moderate output at best).
The main problem I see in the inductors that are connected in parallel with the speakers. Because of the current driving, their resistance is too small. This mainly affects the midrange driver, but sometimes also the tweeter. As a result, what's left is the deep-toned sound that seems somewhat chaotic.
In fact, with a lot of power with a D amplifier you can get a lot of bass out of a small speaker. The days of jukeboxes are over.
If there are passive crossovers, be prepared to drive with higher powered amp and use high efficiency speakers.
And is not related to the sound of bipolar transistors topic.
Regards.
And is not related to the sound of bipolar transistors topic.
Regards.
With enough class D watts, DSP, and displacement you can make it sound any way you want, right up till the magic smoke comes out. But with one of these small current-drive amplifiers ( be it tubes or transistors) one has to rely on the intrinsic properties of the speaker driver itself to get any dam bass.
I have not read this thread, just the title. Here is my bjt buffer, no negative feedback, very low distortion, if you want to hear linear bjt output.
https://www.diyaudio.com/community/threads/output-bjts-for-buffer.386324/
https://www.diyaudio.com/community/threads/output-bjts-for-buffer.386324/
I think all of your requirements are met here, but the sound could be much better.
Compare
https://www.diyaudio.com/community/threads/current-drive-for-loudspeakers.250272/post-3917799
Now you've really made me curious. I listened to several Pass amplifiers on YouTube... These amplifiers have a problem in the high frequency range. However, I wouldn't describe it as warm, but more like dust… And so I remembered Miller Effect. In fact, the optimal operating point of the MOSFETs is in the Miller Plateau area.
This means the destruction of linearity as frequency increases.
I looked at the Nelson Pass circuits. They operate just above Vth, i.e. far from Miller Plateau. Now I'm trying with a simulation. It is a simple common source circuit. With the standard measurement at 1 kHz, the output voltage (Vd) looks relatively harmless even at full scale:
At 10 kHz the situation changes drastically:
The sinus becomes sawtooth-like. And there is a kink at Ud = Ugs, which indicates the so-called “pinch-off” effect. This is where the audible "pulverization" of the high tones can come from.
At 10 kHz the situation changes drastically:
The sinus becomes sawtooth-like. And there is a kink at Ud = Ugs, which indicates the so-called “pinch-off” effect. This is where the audible "pulverization" of the high tones can come from.