[Deutschefach]

The ah90 is only going to draw as much amps as it needs. Voltage must match but amps can exceed.
My A26 is plugged into a 20a wall outlet.
It probably only draws 3a of that 20a at most!

What a great response! Volts must always be matched and amperage must be in reserve. If the baseline amperage is 2.5 then double would be likely be the most ever needed.. Hence his suggestion of 5 amps.

Your point is well made. Since amperage is reserved until weakness occurs, only the missing current is transferred to the DAC. Amperage is a measure of reserve current availability.

If true, then excess amperage in an LPS should not present a problem.

Too much is not enough. Is there a generally accepted principle here?
ie.
Baseline amperage x 2 or 3? That would allow a LPS to keep amperage constant in the LPS, by load matching at least 100% the attached device(s) needs,pulling all their need for current from the LPS when needed. Do you agree or have other observations?

 

[camrector]

Amperage is a measure of reserve current availability.

Amperage is a measure of the electrical current. Current is a count of the number of electrons flowing through a circuit. One amp is the amount of current produced by a force of one volt acting through the resistance of one ohm.
Ohm’s law: I =V/R is going to determine what the current will be.
Many devices have there own way to limit current flow. The LPs is a transformer that’s connected to AC power mains, and limits the amount of current flowing through its primary windings via inductance.
Other devices have pulse-width modulation, switching themselves on and off multiple times per second, then a capacitor is used to smooth the current to avoid the short peaks.
Most loads do not have a fixed value of resistance, so the current is not directly proportional to the voltage. The AH90 is only going to take whatever it needs. The power supply could provide any current from 0 to 100A whatever the load (AH90) wants. It does not force 100 A out. If the load wants 100A, fine. But if the load wants only 50 mA, that's fine too.
Think of it this way:
How does your bath not fill instantly when you turn on the tap (infinite current) despite the fact the reservoir (PSU) could also fill all the baths in the street at the same time?
Why does your bath fill at a constant rate?

Answer: That fill rate (current) is determined by the pressure (PSU voltage) and pipework (resistance) and has nothing to do with the capacity of the reservoir (PSU current rating)

 

[Deutschefach]

Amperage is a measure of the electrical current. Current is a count of the number of electrons flowing through a circuit. One amp is the amount of current produced by a force of one volt acting through the resistance of one ohm.
Ohm’s law: I =V/R is going to determine what the current will be.
Many devices have there own way to limit current flow. The LPs is a transformer that’s connected to AC power mains, and limits the amount of current flowing through its primary windings via inductance.
Other devices have pulse-width modulation, switching themselves on and off multiple times per second, then a capacitor is used to smooth the current to avoid the short peaks.
Most loads do not have a fixed value of resistance, so the current is not directly proportional to the voltage. The AH90 is only going to take whatever it needs. The power supply could provide any current from 0 to 100A whatever the load (AH90) wants. It does not force 100 A out. If the load wants 100A, fine. But if the load wants only 50 mA, that's fine too.
Think of it this way:
How does your bath not fill instantly when you turn on the tap (infinite current) despite the fact the reservoir (PSU) could also fill all the baths in the street at the same time?
Why does your bath fill at a constant rate?

Answer: That fill rate (current) is determined by the pressure (PSU voltage) and pipework (resistance) and has nothing to do with the capacity of the reservoir (PSU current rating)

Thank you sir!!

 

[Deutschefach]

Thank you sir!!

Then how is proper minimum reserve of Amperage calculated? Is there a formula?

 

[M43T7N]

Note my reference post on linear power supplies for the AH90:

Towards High-End with the AH90 - notes on linear power supplies
I use the AH90 with a linear power supply (LPS) since two months now and wanted to make that post for a while but haven’t had the time. Now here you go:

(1) Stock power supply:
As can easily be seen on one of the official product pictures, the AH90 is powered by a Hi-Link HLK-20M12 switched mode power supply. This is a cheap 3€ component. Find attached the datasheet (english). Relevant technical specs are:

No-load rated output voltage 12.0±0.1 Vdc
Full-load rated output voltage 12.0±0.2 Vdc
Short time maximum output current ≥1700 mA
Long time maximum output current 1600 mA
Voltage regulation ±0.2 %
Load regulation ±0.5 %
Output ripple and noise ≤150 (mVp-p)

Of course there are (what I believe) filtering components on the AH90’s pcb, so the actual ripple/noise is likely lower. I am not sure whether the 12v dc input is also passed through that filtering stage or not, but for simplicity, this is the spec to beat when choosing a LPS for the AH90.

The manufacturer gustard mentioned multiple times in this thread that the input voltage can be 12-15V and a minimum of 2.5A are recommended for a LPS. Assuming that a higher voltage increases components thermal losses and potentially reduces longevity, I decided that I want to power my AH90 with 12v. Note that many options below are available in a 15v version.

(2) List of compatible options I considered:
[EU price excl. vat and taxes; consider 1.00€=1.07$].
- DIY option
- [sub 100€] cheap generic AliExpress LPS link
- [100€] LHY AUDIO LPS25VA
- [150€] Fiio PL50 (2023)
- [150€] LHY AUDIO LPS50VA
- [220€] pd-creative SUPER LOW-NOISE PSU – 12V DC (EU-only)
- [240€] ATL Audio L-50
- [250€] ifi iPower Elite
- [265€] LHY AUDIO LPS80VA
- [290€] SBOOSTER BOTW P&P MKII
- [300€] ATL Audio L-50-v.2

When it comes to these options, I wanted to maximize technical performance at a threshold price that still makes sense relative to the AH90s price. For me, this threshold price is 200€ net so that the whole package would be 700€ net on a DAC, headphone amp and streamer with a linear power supply. The next best option that has all those features in one box is (to my knowledge) the hifiman serenade r2r dac, for 1100€ net. So 700€ net would still be an excellent value.

(3) What I decided to do:
Unfortunately, I found that most of these products provide only very limited information on their technical performance. Most relevant for audio is ripple and noise performance which is often provided in different units that are hard to compare and sometimes not specified at all. The pd-creative is noteworthy as each unit ships with a measurement report. The AliExpress options seemed to be best value for money at first, but customers often report poor quality and randomly changing components such as capacitors. I also question whether they are CE certified and if it’s a good idea to keep them running in absence.

What I then did is look for DIY options. There are many LPS boards that just need plugging a transformer. See examples on Audiophonics. What I ended up with is a product called LinearPi Mk II Dual (see datasheet here). This is a dual output LPS board that is build around a LT3042 linear voltage regulator. The LT3042 is considered exceptionally quiet and ideal for sensitive systems (see specs here and technical article here).
To power that, I use a Block RTE100/12x2 100VA toroidal transformer. This solution should provide excellent technical performance. I use the second output for my network switch right now but I plan to power a phono stage with it at some point. Also at some point I’ll put everything in a steel case with en emi-filtered IEC inlet, but right now I just appreciate the open look.

(4) Does it improve sound?
Yes. The difference is actually quite noticeable to my ears which surprised me. I would not go so far and say 'day and night difference', but worth spending 200€ (also considering the DIY fun and second output). Describing the exact differences in sound would be super subjective, so I won't.

Note that the manufacturer of the LinearPi IanCanada is launching a LinearPi Pro at some point with a higher power rating. The normal LinearPi is running quite hot and if I were in the market for a LPS right now I would probably wait for that or consider spending more for a higher power option.

Hope you find this helpful!

The default switched mode psu from the AH90 provides only 1.6A (peak 1.7A) and I doubt that the AH90 even draws anywhere near that 19.2W. The cpu is a low power dual core ARMv7 with 117mb ram (more on that in a later post). The AK4499EX draws max 24mA. A few opamps for the output stage and headphone amp and the AH90 will never draw more than 10W. I'll measure and check that at some point.

So the verdict is that even a 2.5A linear psu will have plenty reserves for the AH90. There are other characteristics that need to be considered such as noise/ripple and the transient response. Those parameters may or may not improve with a higher current psu. For example: consider a 300€ psu rated for 6.5A. For the same money, you will get a power supply with less amps that performs better in terms of noise/ripple (see list of options in the above post).

I have a lot of experience with IAN Canada boards. I would not be using the Linear Pi’s to power the Dac. They are better suited for 5v or less.

In principle I agree but only for thermal reasons and the heatsink getting quite hot with 12v. I power mine with a 12v transformer and Ian recommends a 9v transformer for 12v dc operation, which would reduce thermal losses. Also I measured the LinearPi's output voltage with a multimeter under full (and changing) load and it remained at precisely 12.00V in all conditions, suggesting that (a) the LinearPi has no issues at all powering the AH90 and (b) that 2.5A is in fact plenty for the AH90.

I'm not saying that the Linear Pi is the best choice for the AH90, it's just that at this specific price I didn't find any other diy or non-diy option that has better technical performance. 90€ + 50€ for a quality transformer is pretty much maximizing technical performance at 140€. Hard to beat.

A 5A linear psu with exellent noise/ripple performance would certainly make the AH90 sound better but is expensive and then at some point the AH90 does't make sense anymore as we're reaching A26 pricing.

 

[Deutschefach]

Note my reference post on linear power supplies for the AH90:


The default switched mode psu from the AH90 provides only 1.6A (peak 1.7A) and I doubt that the AH90 even draws anywhere near that 19.2W. The cpu is a low power dual core ARMv7 with 117mb ram (more on that in a later post). The AK4499EX draws max 24mA. A few opamps for the output stage and headphone amp and the AH90 will never draw more than 10W. I'll measure and check that at some point.

So the verdict is that even a 2.5A linear psu will have plenty reserves for the AH90. There are other characteristics that need to be considered such as noise/ripple and the transient response. Those parameters may or may not improve with a higher current psu. For example: consider a 300€ psu rated for 6.5A. For the same money, you will get a power supply with less amps that performs better in terms of noise/ripple (see list of options in the above post).


In principle I agree but only for thermal reasons and the heatsink getting quite hot with 12v. I power mine with a 12v transformer and Ian recommends a 9v transformer for 12v dc operation, which would reduce thermal losses. Also I measured the LinearPi's output voltage with a multimeter under full (and changing) load and it remained at precisely 12.00V in all conditions, suggesting that (a) the LinearPi has no issues at all powering the AH90 and (b) that 2.5A is in fact plenty for the AH90.

I'm not saying that the Linear Pi is the best choice for the AH90, it's just that at this specific price I didn't find any other diy or non-diy option that has better technical performance. 90€ + 50€ for a quality transformer is pretty much maximizing technical performance at 140€. Hard to beat.

A 5A linear psu with exellent noise/ripple performance would certainly make the AH90 sound better but is expensive and then at some point the AH90 does't make sense anymore as we're reaching A26 pricing.

 

[Deutschefach]

Thanks do you have other LPS suggestions?

 

[M43T7N]

Thanks do you have other LPS suggestions?

None that I have experiences with. In my original post in section (2), I mention 9 compatible non-diy options. Somewhere in that post is also a link to the Audiophonics diy-boards.
From all non-diy options out there, to me the pd-creative SUPER LOW-NOISE PSU – 12V DC looks most promising. Ships from Poland, comes with it's own measurement report and the whole thing is in a steel (rather than aluminium) case with separate compartment for the transformer. Price is around 260€ with VAT, so not cheap but could be worth it.

 

[camrector]

Note my reference post on linear power supplies for the AH90:


The default switched mode psu from the AH90 provides only 1.6A (peak 1.7A) and I doubt that the AH90 even draws anywhere near that 19.2W. The cpu is a low power dual core ARMv7 with 117mb ram (more on that in a later post). The AK4499EX draws max 24mA. A few opamps for the output stage and headphone amp and the AH90 will never draw more than 10W. I'll measure and check that at some point.

So the verdict is that even a 2.5A linear psu will have plenty reserves for the AH90. There are other characteristics that need to be considered such as noise/ripple and the transient response. Those parameters may or may not improve with a higher current psu. For example: consider a 300€ psu rated for 6.5A. For the same money, you will get a power supply with less amps that performs better in terms of noise/ripple (see list of options in the above post).


In principle I agree but only for thermal reasons and the heatsink getting quite hot with 12v. I power mine with a 12v transformer and Ian recommends a 9v transformer for 12v dc operation, which would reduce thermal losses. Also I measured the LinearPi's output voltage with a multimeter under full (and changing) load and it remained at precisely 12.00V in all conditions, suggesting that (a) the LinearPi has no issues at all powering the AH90 and (b) that 2.5A is in fact plenty for the AH90.

I'm not saying that the Linear Pi is the best choice for the AH90, it's just that at this specific price I didn't find any other diy or non-diy option that has better technical performance. 90€ + 50€ for a quality transformer is pretty much maximizing technical performance at 140€. Hard to beat.

A 5A linear psu with exellent noise/ripple performance would certainly make the AH90 sound better but is expensive and then at some point the AH90 does't make sense anymore as we're reaching A26 pricing.

Yeah it’s the thermal reasons why pushing that Linear to 12v I feel is unwise.
Totally agree that a low noise/low ripple supply is pricy. Maybe some Ali one could suffice but I don’t know how low noise/ripple they are. $300 at least is the starting point.

 

[camrector]

Then how is proper minimum reserve of Amperage calculated? Is there a formula?

Determined by the components used in the device.That info is on the spec sheet supplied to the designers.

 

[Deutschefach]

None that I have experiences with. In my original post in section (2), I mention 9 compatible non-diy options. Somewhere in that post is also a link to the Audiophonics diy-boards.
From all non-diy options out there, to me the pd-creative SUPER LOW-NOISE PSU – 12V DC looks most promising. Ships from Poland, comes with it's own measurement report and the whole thing is in a steel (rather than aluminium) case with separate compartment for the transformer. Price is around 260€ with VAT, so not cheap but could be worth it.

I will inform myself about it. I know another in the UK. I will send you the link for it so we can discuss it too.

 

[Deutschefach]

Determined by the components used in the device.That info is on the spec sheet supplied to the designers.

Is there a straighter answer to my question?

 

[camrector]

Is there a straighter answer to my question?

Hmm
When you put a 30w lightbulb in a lamp the box says 30w from the manufacture.
When you want to put a chip in a dac that needs 50 mA TI, AKM, ESS etc say so on the spec sheet.

 

[Deutschefach]

So the consumer has no idea

 

[camrector]

So the consumer has no idea

Of the power requirements of individual chips and boards? No