Test with 800w $44 Aliexpress 48v SMPS
I bought one of these 800w 48v SMPS designed for LED lighting from Aliexpress a few months ago. I set its internal switch to 120VAC input (220VAC is an option), and wired it to an EIC socket with earth ground.
I connected it to the amp, not expecting much as I had already tested out a much more expensive Connexelectronic 800w SMPS ($150) and was dissappointed with the excessive added hash noise.
Well the cheap $44 one from Aliexpress surprised me. It is not noisy at all, and in fact, is close/idenmtical to the 12v battery and DC step up in terms of low noise performance.
Here is a photo of the setup shown connected to speakers for listening:
Here is a closeup of the inside of one of these SPMP from venfor AIFENG on Aliexpress. I had to disconnect the internal fan cable and let it run naturally cooled for now. The fan was way too noise and this deserves a better fan. At normal volumes, it is not even warm without a fan:
Here is the measured FFT for 8.12Vrms into 3.3ohm load:
Here is the FFT fo 4.36Vrms (graph label is incorrect) into 3.3ohm load:
I bought one of these 800w 48v SMPS designed for LED lighting from Aliexpress a few months ago. I set its internal switch to 120VAC input (220VAC is an option), and wired it to an EIC socket with earth ground.
I connected it to the amp, not expecting much as I had already tested out a much more expensive Connexelectronic 800w SMPS ($150) and was dissappointed with the excessive added hash noise.
Well the cheap $44 one from Aliexpress surprised me. It is not noisy at all, and in fact, is close/idenmtical to the 12v battery and DC step up in terms of low noise performance.
Here is a photo of the setup shown connected to speakers for listening:
Here is a closeup of the inside of one of these SPMP from venfor AIFENG on Aliexpress. I had to disconnect the internal fan cable and let it run naturally cooled for now. The fan was way too noise and this deserves a better fan. At normal volumes, it is not even warm without a fan:
Here is the measured FFT for 8.12Vrms into 3.3ohm load:
Here is the FFT fo 4.36Vrms (graph label is incorrect) into 3.3ohm load:
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Same test at same condition, but different day. Not sure what happened last night but measurement now has 3rd harmonic in place.
So I decided to test the ConnexElectronic 800w 48v SMPS with this amp and am getting a pretty good lower noise background. The hiss that was present when I tested this PSU with both 3E and clone TI EVM, are no longer present on the present amp. So that is a pleasant surprise. The noise baseline however, rose by about 7dB to 10dB relative to the $44 800w LED SMPS and 12v battery DC/DC converter. Also, some small mains peaks at 60/120/240/360Hz are now visible on the ConnexElectronic.
Listening to the ConnexElectronic now and it seems fine - no audible hiss and very-very faint hum if ear pressed to cone.
So I decided to test the ConnexElectronic 800w 48v SMPS with this amp and am getting a pretty good lower noise background. The hiss that was present when I tested this PSU with both 3E and clone TI EVM, are no longer present on the present amp. So that is a pleasant surprise. The noise baseline however, rose by about 7dB to 10dB relative to the $44 800w LED SMPS and 12v battery DC/DC converter. Also, some small mains peaks at 60/120/240/360Hz are now visible on the ConnexElectronic.
Listening to the ConnexElectronic now and it seems fine - no audible hiss and very-very faint hum if ear pressed to cone.
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In BTL mode, add a bit more resistance in series with the inductor on one leg of the output. Circa 0.33R or 0.67R. These small asymmetric imbalances can result in increased even order distortion.
Easier to drive the amp with a SE Class A preamp like your DCA. (You will need two of them since inout is balanced).
Easier to drive the amp with a SE Class A preamp like your DCA. (You will need two of them since inout is balanced).
Make sure your LDO has enough cooper for heat dissipation after changing pinout as there's always a preferred pin for this.
You may also check for replacements for L171/181 in a more common footprint like 0805/1206/1210. (Or have a combo fp)
For fsw sync i'd recommend (additional) u.fl. jack rather than simple pinheaders and some kind of series termination.
You may also check for replacements for L171/181 in a more common footprint like 0805/1206/1210. (Or have a combo fp)
For fsw sync i'd recommend (additional) u.fl. jack rather than simple pinheaders and some kind of series termination.
We have a special micro 3 pin connector at present but very small and probably needs pre-made cables. Will switch to usual 3 pin locking Molex. What do you mean by series termination? You mean add resistor for cable impedance termination? What if I wanted to sync 4 amps together - can it be done with a serial bus?
I am reviewing latest update from JPS64. Doesn’t look like changing the frequency sync connector is practical so we will stick with pre-made Würth 2.54mm 3-pin. Also, solder jumper pads will he kept as PCB selector jumper pins would mean complete redesign as well. 3.3v LDO has more heat dissipation copper for tab. Use of solder jumper pads is actually better from reliability and ruggedness standpoint for professional PA use or for mounting amp inside subwoofer cabinet where equipment is subject to mechanical shocks, vibration, and bumps.
Thanks you, JPS64!
Looks great.
Thanks you, JPS64!
Looks great.
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The unit I got from AliExpress (48v and 800w) does not have any audible whine or noise once you disconnect the fan. The fan is loud though. Case and heatsink is not warm at all under normal use - for high power use, swapping noisy fan out with a quieter unit would be helpful.
AliExpress
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