Switched Mode Power Supplies (SMPS)

[Cristi]

yes, there is a jumper which must be putted to work with 110V. for a class A amplifier i recommend a resonant type power supply such as SMPS500R or better SMPS800R, considering that the amplifier will draw continuously at least 1.9A at 80V.

 

[firestorm]

Hi Cristi,
thanks for your reply.

The A1000SMPS I have is labelled OK 110V on the main transformer.

I have looked at the pcb, I see a wire link labelled 110V, right hand side of the second main capacitor. So if I remove the wirelink I can use it AC in at 240V?

What is the black jumper for? The one left handside of the 1st main capacitor.

______________________________________________________________________
For the 2 x 50W class A amp

Is one SMPS800R sufficient ? or better with 2 x SMPS500R ?

Or can I improve the isolation of one SMPS800R with extra capacitance downstream of the smps ? I presume there is a limit to the capacitance I can use, as it may trip the current limit on switch on ?

Can you recommend a practical way of making the smps quieter for amps with lower psrr?

Regards
fs

 

[Cristi]

The first A1000SMPS version had a small mains auxiliary transformer used to supply the control section of the smps and the remote section (which none of the ppls actually used) then i decided to remove in the later versions, and i have made the supply of the control section more elegant, using a start up circuit. if you have one of that versions with transformer, this must be changed with a 230V transformer as well, and remove the jumper.

for the class A amplifier, using 2 SMPS500R instead of a single SMPS800R will give better channel separation and lower temperature rise.

 

[firestorm]

I'll take a photo of the smps later.... don't want to fry it.

 

[alkasar]

for the class A amplifier, using 2 SMPS500R instead of a single SMPS800R will give better channel separation and lower temperature rise.

Hi Cristi,

I saw in some documents you mention regulated SMPS is not mandatory for ClassAB, as these amps have a good psrr.
Which SMPS is best in your opinion for a ClassA : 2xSMPS500R or 2xA500SMPS ?

 

[mige0]

Hi Cristi,

I saw in some documents you mention regulated SMPS is not mandatory for ClassAB, as these amps have a good psrr.

I would not necessarily second that - good load regulation IMO is mandatory for detailed sound with AB amps (any amp that highly modulates current demand I'd say) - I just did some basic audition with a MW-SMPS and some additional bypass cap mods.

Certainly, the relatively stiff regulation of the SMPS with respect to a mere linear PSU pays off *if* you manage to preserve nice flow in presentation.

Second on my list I'd put line regulation, as with linear PSU I clearly notice differences in quality of the power grid that are periodically with working days / weekend.

As switched amps do not seem to have *that different* PSRR than AB amps, I'd rather go for the same with those amps as well.


Michael

 

[firestorm]

Hi Cristi,
Heres a photo of the actual smps - it appears to have the auxillary transformer, the light blue coloured one I guess.

An externally hosted image should be here but it was not working when we last tested it.

larger photo
img198.imageshack.us/f/p1240364.jpg

The transformer seems to have 10 connections in total, which seems a lot, but many may be just for stability and no internal connections. What type of transformer do I need to change it for ? I've looked at the pcb, it must be 3 layers or more, as I can't see enough of the tracks.

An externally hosted image should be here but it was not working when we last tested it.

larger photo
img708.imageshack.us/i/p1240367.jpg

Is it practical to change it from 110v to 230v ?

I know there is +- 10% adjustment Vout, if I need lower it to say 40V, does the transformer ratio need to change (It is 50V now)?

Thanks
fs

 

[mige0]

Christi - a question
- with the SMPS controller chips in use - is there a a chance to exactly determine on how the internal feedback loop is working in terms of setting parameters of bode diagram (feedback amount and phase reserve) ?

Michael

 

[gautamz]

I have been considering building an amp based on the 500W LME49810 or the TA3020, powered by an SMPS.
The specs for the 500W LME49810 say that two separate voltages are required - +-78V and +-84V. Which would be a suitable SMPS at the connexelectric site for this? Can the SMPS500R or the SMPS800R be modified to provide the different above voltages?
If I wanted to run the TA3020 in BTL mode with ~300W at 8ohms, what would be the ideal supply voltage and would the SMPS500R be suitable for it?

Separately - which would provide better bass (tight, fast and detailed) the LME49810 or the TA3020?

 

[Cristi]

Al, for a class A amplifier, i recommend a regulated SMPS, since the bias current of the amplifier power stage is high, an unregulated power supply will have considerable higher ripple. a linear supply for a class A amplifier use huge capacitors, with values starting from tens of mF to even 0.1F or more. SMPS500R can be used for a class A amplifier with output power up to 100W. considering the amplifier poor efficiency, the power supply would have to supply about 2.5-4 times this power.

Firestorm, please send me the pictures by mail, can't see them here, image$ucks cannot be accessed here...

Michael, the control loop ss model of the LLC converter is determined based on the Bode plots obtained by measuring the the power supply with network analyzer (or with poor's man measurement rig: oscilloscope, signal generator, injection transformer :-( ) then the poles and zeros from the feedback loop compensation can be determined and the power supply can be tuned for proper response modifying the components values.
After tuning the control loop components values, I measured the crossover frequency 8.42KHz with a phase margin of about 50*

Gautamz, the LME49810 amplifier modules require 4 rail supply voltage for best performance when they are supplied from a linear unregulated power supply. the driver stage is supplied with a 5-10V higher voltage than the power stage. when the modules are supplied from a regulated smps, two rail supplies are enough. for LME49810-500W the SMPS2000R can supply 2 modules, and the voltage should be set to +-80V.
for TA3020 in BTL mode, if the power will not exceed 300W, the SMPS500R is enough.
i consider that the LME49810 sound is better.

 

[Cristi]

Bigger power supply is coming: Connexelectronic
3600W, 2-4 supply rails, suitable for class AB and class D and class H amplifiers.

 

[dudaindc]

Bigger power supply is coming: Connexelectronic
3600W, 2-4 supply rails, suitable for class AB and class D and class H amplifiers.

Really nice Cristi - you always have good stuff coming.

I "need" to get one of these too...

 

[avr300]

Big dilemma..

I need to power 5 * UcD180, mounted in the same enclosure.

I'm looking at either 2 * SMPS500R or - and perhaps better, one SMPS2000R.

Gentlemen - pros and cons, pls.

 

[Cristi]

For best performance i recommend one SMPS500R for two modules and one SMPS800R for the other 3 modules, or a single SMPS2000R for all 5 modules.

 

[avr300]

Thanks Cristi.

Where do I see the shipping cost for ex. 2 * SMPS500R sent to Denmark ?

 

[Cristi]

Please follow the order steps from the website, and at the end the shipping cost will be calculated.

 

[avr300]

Roger. Thx.

 

[fwki]

Cristi,
On the SMPS800R, is the mains power connector IEC C14 which would accept IEC C13 connector? Also instead would it be possible to get the SMPS800R with a screw-type connector for 12 AWG mains?

 

[Cristi]

Better not use the C13 type, for safety reasons. the cable of this connector has the power line exposed and can be touched accidentally. screw type connector can be used.

 

[fwki]

Yes, safety is important on SMPS. Then I will order this weekend SMPS800R with the screw type connector instead of IEC for the mains similar to SMPS500R.