Umbilicals between pre-reg and phono amp must be shielded to protect DC signal from EMI and radio frequency interference. One end of the shield inside power supply enclosure goes directly to PS ground. Other shield end should go to phono ground ( inside connector if you use it) via 10nf ceramic DISC capacitor, Z5U tem. co. For additional protection every power rail ( +/-) inside preamp should be connected to enclosure directly via the same capacitors keeping leads as short as possible.
In my Paradise I grounded both output RCA connectors directly to metal enclosure, they are very close to each other. Even without any ground lifting resistors, there is no any hum
In my Paradise I grounded both output RCA connectors directly to metal enclosure, they are very close to each other. Even without any ground lifting resistors, there is no any hum
I've built 40+, never used shielded cable between chassis and some people run 2m psu leads. I do put some 30uf caps on the rail inputs to the shunt though.
It's very easy to get a very quiet Paradise build, you have to connect them up to almost pathologically stupid TT or pre-amp setups to make them noisy.
It's very easy to get a very quiet Paradise build, you have to connect them up to almost pathologically stupid TT or pre-amp setups to make them noisy.
Nice to see this thread is still active. I didn’t think it was, and I didn’t bother to ask.
First, I would like to thank sq225917 for his generosity in giving me his time and experience with a previous build some time ago (long story). I couldn’t get on top of the meandering amp voltages, and with replacing transistors with diminishing patience and clumsiness, I damaged the boards and just gave up and packed it away.
Months later I came across some free PCB software, and decided to try my hand at making my own boards(retired and time rich). Why not start at the deep end, with no previous PCB layout experience and with only a rudimentary understanding of things electrical.
It took many hours, but I enjoyed the learning experience, and for no other reason, other than it seemed like a good idea at the time, I manipulated the layout to include the Calvin buffer circuit on the same board.
Anyway here it is, the boards are 2oz copper and 2mm thick……… and not red.
So far this regulator is giving all the right voltages in the right places (happy days), except two Led’s L11 and L12 (positive side) dim after initially lighting up.
The PSU from my previous build is now only delivering +/- 24.5V. The regulator is drawing 163.5ma per side. My understanding is that it should be 157ma with the 8.2 Ohm power resistors. The PSU gives about +/-35VDC unloaded and the filter boards drop it by about four Volts.
While measuring I checked between the board ground and the input terminal and was surprised at the results: Ground to 0V = -2.4V, G to +V = +22.4V, G to -V = -27.1V. I have no idea why this is so, but it doesn't seem good.
The power transistors used in this reg. are FQPF11P06/FQPF20N06 and MJF4511G/MJF4411.
Comments welcome.
First, I would like to thank sq225917 for his generosity in giving me his time and experience with a previous build some time ago (long story). I couldn’t get on top of the meandering amp voltages, and with replacing transistors with diminishing patience and clumsiness, I damaged the boards and just gave up and packed it away.
Months later I came across some free PCB software, and decided to try my hand at making my own boards(retired and time rich). Why not start at the deep end, with no previous PCB layout experience and with only a rudimentary understanding of things electrical.
It took many hours, but I enjoyed the learning experience, and for no other reason, other than it seemed like a good idea at the time, I manipulated the layout to include the Calvin buffer circuit on the same board.
Anyway here it is, the boards are 2oz copper and 2mm thick……… and not red.
So far this regulator is giving all the right voltages in the right places (happy days), except two Led’s L11 and L12 (positive side) dim after initially lighting up.
The PSU from my previous build is now only delivering +/- 24.5V. The regulator is drawing 163.5ma per side. My understanding is that it should be 157ma with the 8.2 Ohm power resistors. The PSU gives about +/-35VDC unloaded and the filter boards drop it by about four Volts.
While measuring I checked between the board ground and the input terminal and was surprised at the results: Ground to 0V = -2.4V, G to +V = +22.4V, G to -V = -27.1V. I have no idea why this is so, but it doesn't seem good.
The power transistors used in this reg. are FQPF11P06/FQPF20N06 and MJF4511G/MJF4411.
Comments welcome.
First of all, congratulations to your design! The PCB looks very clean and it seems you have the Calvin buffers in place already, nice!
The input voltage to the regulators +/- 24.5V is fine, and the current draw looks OK. I do not understand your later measurements: Ground to 0V (which ground, which 0V?)? The grounds of the regulators and amplifier should be connected anyway.
When the regulator is operating correctly, the supply voltages should be +/-18V (and the connections on the board were put to make sure the regulator is tested before it is connnected). The regulators will work fine even if no load is connected, as they are shunt regulators - they will simply "sweat" a little more.
We did have a few issues with parasitic oscillation in the regulators, for different device combinations if I remember correctly. The circuit had been adjusted so that it should always work fine, and all the builds pretty much confirmed that. (Mind you, most of the issues were with the LEDs either not soldered or put in the wrong direction.... ). But you may want to check with a oscilloscope if high frequency content is visible in the output voltages.
Maybe you can also provide complete voltage measurements at the test points indicated in the original schematic? That would be helpful.
LED11 and 12 dimming is not a good sign, they should all dim with the same brightness as they are all connected in series (and thus see the same current). Is there a solder bridge somewhere, maybe? Then, the LEDs dimming after turn-on is indicating that the shunt regulator is not operating. It should pull "down" the output voltage node to 18V, at which point the LEDs would be lit up with constant brightness. Are the LEDs in the "long" chain all on?
Hope the above helps you isolate the problem..... good luck!
The input voltage to the regulators +/- 24.5V is fine, and the current draw looks OK. I do not understand your later measurements: Ground to 0V (which ground, which 0V?)? The grounds of the regulators and amplifier should be connected anyway.
When the regulator is operating correctly, the supply voltages should be +/-18V (and the connections on the board were put to make sure the regulator is tested before it is connnected). The regulators will work fine even if no load is connected, as they are shunt regulators - they will simply "sweat" a little more.
We did have a few issues with parasitic oscillation in the regulators, for different device combinations if I remember correctly. The circuit had been adjusted so that it should always work fine, and all the builds pretty much confirmed that. (Mind you, most of the issues were with the LEDs either not soldered or put in the wrong direction.... ). But you may want to check with a oscilloscope if high frequency content is visible in the output voltages.
Maybe you can also provide complete voltage measurements at the test points indicated in the original schematic? That would be helpful.
LED11 and 12 dimming is not a good sign, they should all dim with the same brightness as they are all connected in series (and thus see the same current). Is there a solder bridge somewhere, maybe? Then, the LEDs dimming after turn-on is indicating that the shunt regulator is not operating. It should pull "down" the output voltage node to 18V, at which point the LEDs would be lit up with constant brightness. Are the LEDs in the "long" chain all on?
Hope the above helps you isolate the problem..... good luck!
Well, you never know with a Paradise.
After many years of enjoyment I decided some upgrades were the next uplift. First off I swapped the 10k resistor on the input to a naked foil. I wasn't expecting much, but I was intrigued by how the sq changed to being more, err, open and relaxed, spacious... terrible words, but for me it was a welcome improvement.
Next was the PSU. Previously it was a frame transformer, qspeed diodes and a very simple CRC.
Nothing special.
I invested in a couple of sq's transformer PCB and hunted around for a BOM, mainly for the transformer voltages...
I finished up with this...
Ignore the power resistors, that was my fool's errand.
Anyway, I found that the 2x22Vac transformer doesn't quite get the voltage of the PSU up to 24.5Vdc, and not enough to keep the shunt happy, no LEDs are illuminating.
The plan is to replace the transformers with 2x24Vac ones and possibly fit a resistor to get CLCRC. Shame talema don't do 2x24Vac in that same form factor.
After many years of enjoyment I decided some upgrades were the next uplift. First off I swapped the 10k resistor on the input to a naked foil. I wasn't expecting much, but I was intrigued by how the sq changed to being more, err, open and relaxed, spacious... terrible words, but for me it was a welcome improvement.
Next was the PSU. Previously it was a frame transformer, qspeed diodes and a very simple CRC.
Nothing special.
I invested in a couple of sq's transformer PCB and hunted around for a BOM, mainly for the transformer voltages...
I finished up with this...
Ignore the power resistors, that was my fool's errand.
Anyway, I found that the 2x22Vac transformer doesn't quite get the voltage of the PSU up to 24.5Vdc, and not enough to keep the shunt happy, no LEDs are illuminating.
The plan is to replace the transformers with 2x24Vac ones and possibly fit a resistor to get CLCRC. Shame talema don't do 2x24Vac in that same form factor.
Thank you for that. I did have a thought along those lines, I just wasn't sure.
I'll stop chasing ghosts and move on.
Indeed. I went ahead and ordered all the parts from the BOM supplied with my first set of boards. Then found out later that there are better options available.
So I'm stuck with it for now and will hopefully upgrade later.