Seriously Suggest building the DIY PCB Supply.
It's simple , Reliable And affordable... Also 100% noiseless.
I've tried the twin SMPS setup ..not Laptop bricks, but largish metal cased units, (Not for a Pass amp tho)
and one SMPS failed within minutes of first power up.. destroying the output devices on one channel.
I now Refuse to trust to the things on anything I consider worth keeping
It's simple , Reliable And affordable... Also 100% noiseless.
I've tried the twin SMPS setup ..not Laptop bricks, but largish metal cased units, (Not for a Pass amp tho)
and one SMPS failed within minutes of first power up.. destroying the output devices on one channel.
I now Refuse to trust to the things on anything I consider worth keeping
These will work too. Although the output connector is different.
24 Volt Adapter Power Supply | MPJA.COM
24 Volt Adapter Power Supply | MPJA.COM
Danilo look at tubesguy's M2X in this post # 2375 - he has used 2 24V SMPS supplies as you wish to do ( I did something similar but his pictures are much nicer and easier to see how he implemented the supply )
..dB
..dB
A typical linear trafo CRC supply under Class A operation will have quite a bit 120Hz ripple circa 125mV rms. An amp with good PSRR will have no trouble, but many amps do not. In which case, the SMPS will be superior relative to mains hum (noise). Otherwise something like an SLB PSU can bring that 125mV rms down to 1mV rms. However, it’s quite a bit more complicated to make.
The Nightsun 24v 5A supplies I linked work fine and I have not had one go out (I have bought 6 of them). Two power my MoFo and are fine. Two used to power my M2 bit I now use the SLB with an Antek AS-3222 trafo for +/-25v rails at the amp under load.
The 24v Nightsun SMPS brick outputs are isolated from the input mains earth ground. You can connect the common 0v GND to the chassis via a CL60 or NTC 8D-20 to make sure any ground loop hum is suppressed.
The thing SMPS don’t like is to be connected directly to a massive cap bank. If doing so, use a soft start like a cap Mx to ramp up. Otherwise the SMPs will go into auto shutdown because it thinks the output is shorted.
The biggest advantage of SMPS bricks is the fact that they are not connected to mains so are pretty safe for a novice not sure of himself/herself in working with mains and a big toroidal trafo and fuses, EIC inlet shells, mains power switches etc.
Just get a set of 5.5mm coaxial barrel jacks and solder the wires into them to get the series connection and you are set.
Vdi_venna,
Those MPJA units look fine - the $9.94 ones actually look like the ones I got on Amazon.
Make sure the output -ve (barrel sleeve is not internally connected to the earth ground). Use DMM to check conductivity. If they are, they will short out of you connect them in series.
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The PSH of tubesguy doesn't work alone because it needs a CLC board. Is it really necessary?
Danilo
Danilo
That's one way. Another is to find the female connector for the chassis side.
The MPJA supplies show the pin connectors and their function.
A couple of enclosed fanless typle SMPS will solve any cable cutting needs.
LRS-200-24 MEAN WELL | Mouser
THIS is for a Pass Amp .. critical bit of background info..that.
My PS and F6 amp setup is 100% noiseless.
I can stick My ears next to the dustcaps over the Tannoy Compression drivers and hear ZERO noises with the power turned On or Off.
Also with the amp volume on Max.. Zero noise... as in nothing at all.
Absolutely astonishing actually... never experienced this before in 50 years of audio dilettante fiddling.
Plus.. I trust that the PS won't self destruct ..taking out the amp in process.
Bare,
I had a transformer in a linear power supply go bad because a rectifier wire came loose.
It's $60 paper weight now. Took out the output stage on a F6 as well.
I suppose any thing can happen any time.
Ironically, I'd like to build this PS to get that F6 running again.
Don't feel like spending the extra $60 to $80 more to build a linear supply.
Rather use those funds toward a replacement chassis. Old chassis went to F7.
I had a transformer in a linear power supply go bad because a rectifier wire came loose.
It's $60 paper weight now. Took out the output stage on a F6 as well.
I suppose any thing can happen any time.
Ironically, I'd like to build this PS to get that F6 running again.
Don't feel like spending the extra $60 to $80 more to build a linear supply.
Rather use those funds toward a replacement chassis. Old chassis went to F7.
danilom -
After reading through this thread again, it appears to me that the best solution for you is to use the enclosed power supply that xrk linked to in post 16, connected as fabrice has shown in his schematic in post 20. This way you have a solution that has proven to work with xrk's Pass amp, and you will not be exposed to mains AC voltages at all. You don't need the filtering of the CLC board, you just need a three position terminal strip and perhaps the appropriated sized female barrel connectors (to connect to the male connectors of the supplies) so that you can easily set up your +, 0v, and - supply points. You will need to plug both of the supplies into a switched AC power strip so the entire resulting power supply turns on when the strip is switched on.
Make sense? We just want to make sure that no one is injured in the making of this Pass amp.
After reading through this thread again, it appears to me that the best solution for you is to use the enclosed power supply that xrk linked to in post 16, connected as fabrice has shown in his schematic in post 20. This way you have a solution that has proven to work with xrk's Pass amp, and you will not be exposed to mains AC voltages at all. You don't need the filtering of the CLC board, you just need a three position terminal strip and perhaps the appropriated sized female barrel connectors (to connect to the male connectors of the supplies) so that you can easily set up your +, 0v, and - supply points. You will need to plug both of the supplies into a switched AC power strip so the entire resulting power supply turns on when the strip is switched on.
Make sense? We just want to make sure that no one is injured in the making of this Pass amp.
Look at the Aleph J build guide. It may make more sense in that thread. The PSU is the same across most of these builds.
Aleph J illustrated build guide
The one thing that occurred to me is bringing up the amp.
With a SMPS the light bulb test to limit current and using a variac to bring up AC voltage slowly will not work.
I don't think SMPS react well to low AC voltage.
I find a variac to be indispensable when the bias pot direction is questionable.
With a SMPS the light bulb test to limit current and using a variac to bring up AC voltage slowly will not work.
I don't think SMPS react well to low AC voltage.
I find a variac to be indispensable when the bias pot direction is questionable.
An SMPS may well do unpredictable things if the voltage is ramped up slowly, and there is no way of predicting because each design will be different. It could be destructive in some cases.
Once actually operating the SMPS will maintain its output voltage over a wide rangle of input voltages, perhaps input voltages as low as 60 or 70 volts. That means the mains current drawn is correspondingly much higher under those conditions.
The action of a bias pot should always be deducible from examination of the circuit and this allows it to be set in the minimum bias state without worrying over whether it should be turned CW or CCW or whether instructions mean view from the top or view from the bottom.
Once actually operating the SMPS will maintain its output voltage over a wide rangle of input voltages, perhaps input voltages as low as 60 or 70 volts. That means the mains current drawn is correspondingly much higher under those conditions.
The action of a bias pot should always be deducible from examination of the circuit and this allows it to be set in the minimum bias state without worrying over whether it should be turned CW or CCW or whether instructions mean view from the top or view from the bottom.
Good morning, sorry to jump in with a silly question but i have just to do it.
I understand the First Watt F5 design aims to provide really great sound quality.
Can an off-the-shelf switcher have a place in a great sound quality project ?
i have learned how important is power supply quality in an audio amplification unit. This is really surprising to me ... and intriguing as well.
This changes completely my belief.
Thanks a lot, gino
This is one of the most dangerous suggestions I have seen around here.
I hope you realise that MANY, if not most, laptop power supplies have the negative pole connected internally to Mains Earth.
When wired as proposed, the lower laptop supply will be short circuited.
I hope no one will get hurt as a result.
Cheers,
Patrick
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