Regulated supply, does it make sense ?

tinitus · 4th April 2010, 01:19 AM

Hi,

What do you think of regulated supply with classD amps ?
Is it worth the exstra effort and expense

Below is what I have in mind
Intended as TWO stereo amps, possibly bridged

terminator12 · 25th April 2010, 03:06 AM

Generally class D drivers could be used in portable equipments which has a battery or, on big audio systems powered through mains. In any case, these types of systems would have a power management section which does supply regulation using buck converters.

Even if there was not much supply regulation, the class D could be made to sound great using negative feedback around the driver stage.

Baldin · 25th April 2010, 06:39 AM

Hi Tinitus

Class-D has inherently a lower PSRR (Powre Supply Rejection Ratio), than class-AB, meaning that they are more sensitive to both hum (100Hz/120Hz) and other noise from the supply. The noise part can eaasily be the switching noise from one chanel to the other, resulting in beating. The noise will also be modulated and will show as distortion.

These problems are most visible in pure digital systems with no feedback.
See this on PurePath:
http://focus.ti.com/lit/an/slea049/slea049.pdf

But, with most designs today, there are enough feedback so this is not a problem, giving the amp a reasonably good PSRR

So to you question, it depends on the amp.
Using modules from e.g. Hypex will not have any problems with a non regulated supply.

Another thing is also that analog regulated PSUs only have good regulation at lower frequencies, and will probably not help anything for e.g. beating or switching introduced noise.

If you want regulation with Class-D, go for switch more power supplies.
These are inherently regulated, and well suited for class-d, and then you also get rid of the transformer

/Baldin

AP2 · 25th April 2010, 08:15 AM

Hi, all
I agree that some amps have a good PSRR, I know two (Hypex and AudioPower DXA series) just because I've tested. there will be others on the market.
Apart from PSRR, psu switch is regulated and want high performance, there remains the problem of the current response time, this affects the sound amplifier.
(With traditional transformer, add a lot of capacitors and the tone is much rock).
Another problem is the introduction of THD and IMD at low frequency. apart from good PSRR.
MDI-Laboratories two years ago advanced research in this area (apart RIPS) is now testing a new PSU, based on two-channel analog modulator with independent sensing on the outputs.
This system emulates the stage of class AB fully featured digital amplifiers with poor PSRR also ensures 10.000uF per side (real 1500uF).

Certainly the research costs are too high but this is justified by the assignment of patents to other companies operating in different sectors from Audio.

Regards

AP2 · 25th April 2010, 02:37 PM

Hi,
This is a simplified diagram of the concept that I presented before.
This new technique allows the use of small capacitors on the high voltage cell with the benefits of PFC
It also has the advantage of not introducing IMD / Noise on the device (fundamental reason is because when charge on transformer, it is disconnected from AC-line).
The core of the magic is the time base.
unfortunately can not be achieved with traditional chips and then this increased development costs, but ... this is a problem now passed.
This concept was derived from the RIPS, very similar, and was replaced with the second channel analog to better adapt to digital amplifiers, the result on amplifier is incredible ...

Regards

Ali Tait · 25th April 2010, 04:58 PM

Can you buy one of these supplies? If so,where?

AP2 · 25th April 2010, 05:24 PM

Quote:

Originally Posted by Ali Tait

Can you buy one of these supplies? If so,where?

Hi,
this is in production for audiopower.it ,I think is ready
in mid-May.
dimension (156x90x30mm) version 750w max.

Regards

Ali Tait · 25th April 2010, 05:25 PM

Will it be available in the UK? Do you know the price?

AP2 · 25th April 2010, 05:33 PM

Quote:

Originally Posted by Ali Tait

Will it be available in the UK? Do you know the price?

I do not know, but I think the price will be competitive for the product launch.
All models of this new technology can accept 100-130/200-260VAC.

Regards

Ali Tait · 25th April 2010, 07:06 PM

Is this the company?

Audio Power Industries

25th April 2010, 06:39 AM	#3
Baldin diyAudio Member Join Date: Jan 2005 Location: Copenhagen	Hi Tinitus Class-D has inherently a lower PSRR (Powre Supply Rejection Ratio), than class-AB, meaning that they are more sensitive to both hum (100Hz/120Hz) and other noise from the supply. The noise part can eaasily be the switching noise from one chanel to the other, resulting in beating. The noise will also be modulated and will show as distortion. These problems are most visible in pure digital systems with no feedback. See this on PurePath: http://focus.ti.com/lit/an/slea049/slea049.pdf But, with most designs today, there are enough feedback so this is not a problem, giving the amp a reasonably good PSRR So to you question, it depends on the amp. Using modules from e.g. Hypex will not have any problems with a non regulated supply. Another thing is also that analog regulated PSUs only have good regulation at lower frequencies, and will probably not help anything for e.g. beating or switching introduced noise. If you want regulation with Class-D, go for switch more power supplies. These are inherently regulated, and well suited for class-d, and then you also get rid of the transformer /Baldin __________________ Visit www.sensibleaudio.dk or read latest news on Baldin's Blog

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25th April 2010, 03:06 AM	#2
terminator12 diyAudio Member Join Date: Apr 2010	Generally class D drivers could be used in portable equipments which has a battery or, on big audio systems powered through mains. In any case, these types of systems would have a power management section which does supply regulation using buck converters. Even if there was not much supply regulation, the class D could be made to sound great using negative feedback around the driver stage.

25th April 2010, 08:15 AM	#4
AP2 diyAudio Member Join Date: Dec 2009 Location: Italy	Hi, all I agree that some amps have a good PSRR, I know two (Hypex and AudioPower DXA series) just because I've tested. there will be others on the market. Apart from PSRR, psu switch is regulated and want high performance, there remains the problem of the current response time, this affects the sound amplifier. (With traditional transformer, add a lot of capacitors and the tone is much rock). Another problem is the introduction of THD and IMD at low frequency. apart from good PSRR. MDI-Laboratories two years ago advanced research in this area (apart RIPS) is now testing a new PSU, based on two-channel analog modulator with independent sensing on the outputs. This system emulates the stage of class AB fully featured digital amplifiers with poor PSRR also ensures 10.000uF per side (real 1500uF). Certainly the research costs are too high but this is justified by the assignment of patents to other companies operating in different sectors from Audio. Regards

25th April 2010, 04:58 PM	#6
Ali Tait diyAudio Member Join Date: Jun 2007	Can you buy one of these supplies? If so,where?

25th April 2010, 05:25 PM	#8
Ali Tait diyAudio Member Join Date: Jun 2007	Will it be available in the UK? Do you know the price?

25th April 2010, 07:06 PM	#10
Ali Tait diyAudio Member Join Date: Jun 2007	Is this the company? Audio Power Industries

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