The choice of voltage for the power transformer must be chosen taking into account the voltage drop on the rectifier bridge mainly, but also on the resistive elements.
The amplifier can also be powered with 15vdc without problems.
I would recommend that they be powered over 24vdc.
The amplifier can also be powered with 15vdc without problems.
I would recommend that they be powered over 24vdc.
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Not sure to get it. It's always interesting to see how different people made different builds/choices from the same scheme: increased capacitances, single versus double power supplies, several boards versus all on one board, etc.).
Regarding the pcb post #244, looks like the junction/connection between R1-R2-R4 is missing withing the right channel.
Still wondering how the inputs-outputs are connected in this board (one ground per signal, or one ground per input/output, or grounds only for outputs...?).
Regarding the pcb post #244, looks like the junction/connection between R1-R2-R4 is missing withing the right channel.
Still wondering how the inputs-outputs are connected in this board (one ground per signal, or one ground per input/output, or grounds only for outputs...?).
Show me in a drawing.
Especially for you I will put more GND connections.Still wondering how the inputs-outputs are connected in this board (one ground per signal, or one ground per input/output, or grounds only for outputs...?).
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This will be the final version. But I'm not quite sure.
I rushed a bit with attaching the files without paying attention to certain details. I will ask a moderator to change the files with some correct ones.
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Hi again,
Here is a crop regarding what I was saying above.
On the left side, there is a (blue) connection between R1, R2 and R4.
On the right side, R2 and R4 are connected together, but no connection to R1.
Regarding the ground connections, thanks, it's clear now. Will have to take care about loops though
Here is a crop regarding what I was saying above.
On the left side, there is a (blue) connection between R1, R2 and R4.
On the right side, R2 and R4 are connected together, but no connection to R1.
Regarding the ground connections, thanks, it's clear now. Will have to take care about loops though
I'm asking a moderator to delete the files from the 244 post because they are wrong. Thanks.
Hello,
with both values the lower bandpass limit will be below human sensitivity: my advice is to use the best quality component (with reasonable values) you have in your drawer.
Ciao,
Marcello
Circuit for matching HexFETs. by Marcello PelleranoFigure 5
The “active side” HexFETs (Q2) must be matched to ensure the same gain between the two channels (the current source gain can be set by the trimmer (this is another difference respect to the current sources in the Aleph amps, which constrain to select all the devices, not only the “signal” ones).
I built a simple matching circuit shown in figure 5. The bias current is 360mA (calculated as Ibias = (V1 – 4)/R1). It may be regulated with a correct value for the power supply voltage (12V in this case) and for the R value. The HexFET component should be thermal stabilized (a couple of minutes or so) and heatsinked during this test. The selection parameter is Vd, and its value is around 4V. For matching the HexFETs, I think that 0.1V tolerance is plentiful. Devices matched to a few fractions of volt can be achieved, in my opinion, by buying ten or fifteen pieces, and make the matching among these. I bought 50 pieces and found, if I recall right, many 4.17V units.
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Hi knauf1919,
Thanks for the reply and for the fig/method from the original publication.
Now that I have a transistor tester I was wondering if it's possible to match Q2 with the tester instead of the circuit shown in fig5, in order to avoid the thermal stabilization and the heatsink. If the only way is the matching circuit in fig5, let it be
Thanks for the reply and for the fig/method from the original publication.
Now that I have a transistor tester I was wondering if it's possible to match Q2 with the tester instead of the circuit shown in fig5, in order to avoid the thermal stabilization and the heatsink. If the only way is the matching circuit in fig5, let it be
Hi knauf1919,
If the only way is the matching circuit in fig5, let it be
In this case it is the most suitable test. Do it, it's simple.
