I will optimize the pcb for the amplifier. Wait a day or two...
I might be tempted to give this a go and being greedy it would be helpful to have alternative pads for the voltage regulator - the LM317 is TO220 but I have a few TO3P LT1084 devices.
I hope I didn't make a mistake...
I used two capacitors at the output. In this way, you can choose some that are more suitable than the snap-in version.
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I want to ask something.
If the power supply uses two LM317 in series, does it bring any improvement? I don't have a high performance oscilloscope to be able to see this.
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I used two capacitors at the output. In this way, you can choose some that are more suitable than the snap-in version.
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I want to ask something.
If the power supply uses two LM317 in series, does it bring any improvement? I don't have a high performance oscilloscope to be able to see this.
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Just to clarify, I was meaning TO3P devices for the amplifier PCBs, pretty sure the pin outs of LM317 and LT1084 are the same.
This neat little amp looks like it would also work well with the IRFP048, a close descendant of the IRF044 as used in the original Zen amps.
I'm using the IRFP048 to test some new PCBs for the F6. It has characteristics close to my preferred, but nearly unobtanium FQH44N10.
I'm using the IRFP048 to test some new PCBs for the F6. It has characteristics close to my preferred, but nearly unobtanium FQH44N10.
If you are referring to the power supply of the amplifier, I understand that it would be placing two LMs in cascade (one after the other). If so, I do not recommend it, because it adds dissipation and will not be necessary due to the acceptable ripple rejection that the amplifier offers.
On the amplifier side, it would be possible to use several LMs (in parallel) to increase the output power, although very possibly at loads lower than 8 ohms, since it would not be possible to go beyond 40V (limit value of a standard LM). The maximum dissipation per LM should also be taken into account.
Best regards
HI TA,
What about your second best solution if we did the aca premium journey? i mean the FQA28N15
Mouser ordering possible
kr
chris
A few thoughts on the PCB:
Also, even though the component outlines are shown on the bottom side, do not stuff components on the bottom side for mirror imaging. The mosfet and regulator pin arrangements will not work (unless they are rotated 180 degrees).
- silkscreened parts identification on the topside would be most helpful for the builder.
- perhaps adding a place for a film capacitor to parallel the output capacitor instead of two electrolytics paralleled.
- are two paralleled resistors (and large sized) needed at the mosfet gate? With one small resistor, can reposition resistor and input capacitor closer to the mosfet for shorter signal path.
Also, even though the component outlines are shown on the bottom side, do not stuff components on the bottom side for mirror imaging. The mosfet and regulator pin arrangements will not work (unless they are rotated 180 degrees).
The FQA28N15 looks like a decent part, which has also been discontinued recently by the manufacturer. I haven’t had a chance to listen to it, and will probably pursue other parts which are more available instead.
In order to take advantage of the full excursion of the input signal (1 V RMS), I recommend that the R2 / R1 ratio be between 1 to 0.7 approx. At the same time, an attractive cadence relationship is maintained in the distortion profile, typical of a single-ended amplifier.
For R2 / R1 ratios of less than 0.7, it is very likely that the excursions of the input signal must be limited below approximately 0.71 V RMS, according to the common operating modes of the regulators and their limitations, Beyond the fact that the distortion profiles are somewhat different from those expected from a typical single-ended amplifier, in terms of the cadence of the distortion profile compared to that obtained with other ratios greater than R2 / R1.
For R2 / R1 ratios of less than 0.7, it is very likely that the excursions of the input signal must be limited below approximately 0.71 V RMS, according to the common operating modes of the regulators and their limitations, Beyond the fact that the distortion profiles are somewhat different from those expected from a typical single-ended amplifier, in terms of the cadence of the distortion profile compared to that obtained with other ratios greater than R2 / R1.
Very nice work. I’ve noticed the following:
-Silkscreen identification of components R5 and R6 should be swapped.
- Adding a resistor ex R4 to discharge the output cap would be nice. Typical value would be 470 ohm, 2-3W.
Thanks
Eric
It’s ok I’ll put it underneath the PCB.
My problem is like many; I have many speakers, amplifiers and sensitive (fragile)full range, if I forget to add this resistor I will hear a huge thump in the speaker.
My problem is like many; I have many speakers, amplifiers and sensitive (fragile)full range, if I forget to add this resistor I will hear a huge thump in the speaker.
Adding to post #94 by knauf1919. There are speaker terminals on the speakers and speaker terminals on the amplifier. It is easy to place the resistor on the amplifier's speaker terminals.
Are there still possible changes to the scheme, or will it remain as it is?
I will also make a pcb for the power supply whit LM317.
I will also make a pcb for the power supply whit LM317.