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Switched Mode Power Supplies (SMPS)

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Hi Cristi
I have a question regarding your SMPS modules. I would like to use your A1000SMPS modules to power a pair of ClassDAudio.com SDS-254 stereo amp boards that will be used in bridged mode (500w @ 8ohm or 4ohm) - one SMPS per amp board.

Is the A1000SMPS overkill for these modules or will it offer benefits over your SMPS500R model? The price difference between your 2 modules is so small that I'd rather go with the larger supply A1000SMPS if it offers any benefits at all.

The information on the required power supply from classdaudio is as follows...

Power supply
A dual (bipolar) DC power supply of +/-45 to +/-60 Volt should be connected to the terminals V- GND V+ of the 3-position terminal block (shown in photo on following page). The minimum supply voltage is +/- 45V, and the maximum value is +/- 60V. Any value below or above the stated value, and the amplifier will not turn on due to the un-der voltage and over voltage protection that is built into this amplifier. The current ca-pability of the power supply depends on the load and the voltage. The amplifier has a good power supply rejection ratio of -65 dB at 1kHz, and accepts any power supply topology as long as the supply voltages fit in the min and max range.

Any help or advise that you can offer would be much appreciated.
Regards,
Dave.
 
The Output Voltage of the SMPS500R can be adjusted within 10% limits from the small potentiometer which is between the transformer and the output filter caps. Anyway the output is already adjusted to required value and i do not recommend to change this.

There are plenty of SMPS topologies, the resonant ones can be regulated or not, depending on the topology. my advice is that for a class D amp is better to use a regulated smps, either resonant or a regulated hard switched smps.
 
Smps500r

Received the SMPS500R and hooked it up to my ClassD Audio amplifier, (125x2 8ohms,250x2 4ohms), sounds great. More than enough power and the power supply board is smaller than the amp board.
Thanks Cristi for a great item. I have been looking for an SMPS for this amp for quite a while and the 500R seems to be exactly what I have been looking for. :)
 
smps 250 single voltage

Add one 1KR at min 5W resistor on the negative rail, and use the voltage from the positive rail. the voltage can be adjusted from the small pot. from 25 to 32V.

Hello Cristi, i consider recycle my smps250 in a project where i need single +30V voltage.
With the above mod, will the full power (minus about 1w lost in the resistor) be available on the positive rail ? will the smps suffer from working in this "unbalanced" mode ?
thanks
 
To use the SMPS250 for a single rail supply, should add a resistor which will draw about 50-100mA from negative rail, this resistor must be rated at at least 3W in order to dissipate the power properly. a better solution is to reduce the output voltage to +-15V then to connect the load between V- and V+. this can be done if you connect in parallel with R30 a 47K resistor. please note that if the output voltage is too low, the smps can turn off due to low primary bias voltage and loosing of resonance.
 
To use the SMPS250 for a single rail supply, should add a resistor which will draw about 50-100mA from negative rail, this resistor must be rated at at least 3W in order to dissipate the power properly. a better solution is to reduce the output voltage to +-15V then to connect the load between V- and V+. this can be done if you connect in parallel with R30 a 47K resistor. please note that if the output voltage is too low, the smps can turn off due to low primary bias voltage and loosing of resonance.
second method sounds nicer, but R30 is a cms resistor, to difficult for me to solder anything to this :D.
I'll go with the first method.
What about the power available on the positive rail : will it be the full 250W (400W peak) on only half of that ?
 
Hi Alkasar,

I think we are both attempting to do the same thing. I have now successfully tried both methods of connecting the SMPS in single ended mode. I think I will run with the second method as it seems more logical and balanced.

I am attempting to power one of the HiFiMediy V1.1B boards. I have done quite a few mods to my Connex SMPS250 including:

1. Cut 10mm off the top of the heatsink to fit into a 1RU rack case.
2. Changed the 400v 330uF cap for a 35mm high one.
3. Changed the 35v 6800uF caps for 30mm high 4700uF.
4. Changed the thermistor for a 10R 4.5A (15mm).
5. Added the 47k resistor in parallel to R30.

I think this is a much better alternative than the Meanwell 350W 24-27v "Brick" power supply as it is much smaller footprint and fits in a 1RU case (with my mods).

Cristi, perhaps you could manufacture a "Low Profile" version with the option for single ended supply controlled by a jumper? I think there are a lot of HiFiMediy customers that would be very interested.

col.
 
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Hi Alkasar,

I think we are both attempting to do the same thing. I have now successfully tried both methods of connecting the SMPS in single ended mode. I think I will run with the second method as it seems more logical and balanced.

I am attempting to power one of the HiFiMediy V1.1B boards. I have done quite a few mods to my Connex SMPS250 including:

1. Cut 10mm off the top of the heatsink to fit into a 1RU rack case.
2. Changed the 400v 330uF cap for a 35mm high one.
3. Changed the 35v 6800uF caps for 30mm high 4700uF.
4. Changed the thermistor for a 10R 4.5A (15mm).
5. Added the 47k resistor in parallel to R30.

I think this is a much better alternative than the Meanwell 350W 24-27v "Brick" power supply as it is much smaller footprint and fits in a 1RU case (with my mods).

Cristi, perhaps you could manufacture a "Low Profile" version with the option for single ended supply controlled by a jumper? I think there are a lot of HiFiMediy customers that would be very interested.

col.

Yes, we attempt to do the same :)
I agree that second method looks "cleaner" but I am scared to solder a resistor in parallel to a cms.
Could you post a close-up image showing how it looks like once done ?

For Cristi : +1 for a low profile and single voltage option. The next demand will be for a 48-50V smps for the high power T3 amp. Many people pick the large "meanwell brick" because no other easy option available.
 
the aux. voltage is 2x20V DC, at max. 0.5A. the main voltage is adjustable within max. +-10%, that's because the topology used requires tight output voltage to maintain the operation within ZVS range. the output voltage can have one of the following values: +-30V, +-40V, +-50V, +-60V, +-70V all +-5-10% adjustable

I wish to have the SMPS500R Power my ClassDAudio SDS-254 amp with it's primary (50V I believe) & use the 20v Aux to power a Pass B1 preamp (Making a performance integrated amp) in the same chassis.

Is this possible??
 
Any idea when the single voltage SMPS might be available? If it's no higher than 1U (about 44mm), and no wider than about 75mm or 3", then it'll be perfect for installation in a case.

Most electronics project boxes are only 50mm high at most, and usually no wider than 150mm or so. So it's hard to find a power supply that can fit inside an enclosure with an amplifier board.
 
Hi,
I apologize for my english.

I got the Sure-electronics tripath 4 X100w tk2050 board that you certainly know. I'm using a Meanwell power supply (recommended and sold by Sure :rolleyes:) for this board (350W, 24V , 16.4 A). But this PS is too big (22 x12 x 5 cm) and i'm looking for a smallest one. Have you any SMPS wich can match my T-amp ?
 
Hi,
I apologize for my english.

I got the Sure-electronics tripath 4 X100w tk2050 board that you certainly know. I'm using a Meanwell power supply (recommended and sold by Sure :rolleyes:) for this board (350W, 24V , 16.4 A). But this PS is too big (22 x12 x 5 cm) and i'm looking for a smallest one. Have you any SMPS wich can match my T-amp ?
It's very reasonable size. Assuming efficiency 85% it dissipates around 50W, so comes built-in fan.
You may try Vicor's bricks with high pressure fan and channel fin heatsink - are you ready for the noise... or liquid cooling?
 
Sorry, I don't understand your answer :

MY question is, can I use the SMPS250QR or may be the connexelectronic A350SMPS or any other one power supplies with my 4 x 100W tk2050 t-amp ? I suppose I need around 350 W, 24 V and 16.4 A : for example I don't found any amperage indication for the SMPS250QR and I don't know if it's important (I suppose it is :eek:).
 
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