H50 - Boost Mode for 8 Ohm Speakers

According to the spec, when H50 is used with a pair of 8 ohm speakers, the output is 30w per channel.
There is a “boost” mode to achieve 50w. The user’s guide does not specify how to archive this but learned from Arylic support to set H50’s impedance switch to 4 ohm.

However, according to my SPL meeting, setting H50 impedance to 4 ohm did not increase the loudness of my 8 ohm speakers at all. I even tried using a 32v AC/DC converter (instead of the origin 24v), same results.

Anyone has luck getting 50w per channel when using a pair of 8-ohm speakers?


Hi, it’s not really that easy, watts do not directly translate to volume. The perceived loudness, or volume is determined by compression waves in the surrounding air.
This correlation is most influenced by the size and efficiency of the speaker, along with the characteristics of the space. Volume, being three-dimensional, means a larger speaker, under similar conditions, will be perceived as louder than a smaller one.
Efficiency variations among speakers add another layer of complexity to this relationship.
And how do you know your not getting your 50w, have you measured it?

What is the amp chip used in the H50?
I presume it is something different to the B50 and B50 SE as both these amps have ~26V power supply limits. The B50 uses the ACM3128A and the B50SE uses the TPA3116d2.
What I find in the B50 and B50SE is the internal preamp gain is typically set too low to get the maximum power from these amps. The ACP workbench program allows setting the gain for each input and the sound can get much louder for a given set of speakers.

I do not know what amp chip H50 uses.

Good to know ACP workbench may be a solution to obtain higher output (more than 30W for 8-ohm speakers).

Unfortunately I do not PC any more. All computers in my house are Mac. I don’t think ACP workbench work on Mac. :frowning:

Other than using ACP Workbench, is there any other way to adjust the gain? Thx

Hi Collin,

The switch on the back of H50 says 4Ohm and 8Ohm, you should switch to the 8Ohm side to achieve more power output. We’ve placed a voltage boost circuit internally, which is activated when you switch to 8Ohm. This should be the best way to have about 50W per channel for 8Ohm speakers.

Regarding the ACP way, you could increase the gain, but you need to clearly know what you’re doing. It will have distortion for the max level input signal, some people sometimes choose to make it work in distortion mode to have more power and sensitivity. It’s not recommended anyway, it will challenge the power adapter and might make it protect in some condition, which means the room suddenly become silent :slight_smile:

Thanks for the information, Frank.

I am still a little confused…

According to the H50 spec, it says

  • 2x50W @ 4ohm load at 24V
  • 2x30W @ 8ohm load at 24V
  • 2x50W @ 8ohm load at 24V(Boost)
  • 2x80W @ 4ohm load at 32V(Optional)

According to my SPL meter, the Impedance switch does not seem to make a different to the loudness.
(I always remove the 24v input before changing the Impedance.)

If we just focus on the following two possible output (30W vs 50W)

2x30W @ 8ohm load at 24V
2x50W @ 8ohm load at 24V(Boost)

Could you tell me under what condition or settings H50 will produce 30w and under what condition or settings H50 will produce 50w?


Hi Collin,

You only need to put the switch to 8Ohm side before feeding power.

And another point for your reference, the speaker you’ve connected might affect the result if you measure the SPL. It would be more accurate to measure the output power directly. I think all AMP specs will describe in this way.

As a matter of interest, what speakers are you using? Do you know the speakers sensitivity?

Steve and Frank, first, thanks for your willingness to help me and share your knowledge here.

I tested H50 with two sets of speakers:

  1. New Advent (Vintage), 8-ohm, sensitivity = 89dB
  2. KLH Model 5 (2023), 8-ohm, sensitivity = 90.5 dB

My main amp is a Primuluna Tube amp rated at 38watt per channel when using with 8-ohm speakers.

When I use either pair of the speakers, my Primuluna can drive the speaker much louder than the H50 can. In my listening room, I can never crank up my Primaluna pass 12 o’clock before hurting my ears.

However, when I crank up the volume of H50 to 100%, I wish it could go higher.

This experience started my investigation journey here.


Additional multi-meter data points. Hope this is helpful to someone out there.

I use a multi-meter to measure the AC output directly from the H50 and from my primary amp.

I played a 400Hz test tone in a loop.

Here are the readings

H50, 4 ohms setting, 100% volume ==> 2.384v
H50, 8 ohms setting, 100% volume ==> 2.385v

Let’s put weather if H50 really can produce 50w per channel on the side.
Let’s focus on the following two specification bullets for now.
(1) 2x30W @ 8ohm load at 24V
(2) 2x50W @ 8ohm load at 24V(Boost)

Per Arylic support team, the impedance switch determines the output wattage of H50. But my SPL readings and Multi-meeting say that is not true.

Can someone shed some light on how to configure H50 to produce 30W and 50W?

We’re the voltages measured with the speakers connected?

My voltage readings were measured from the speaker outputs on the back of H50. Speakers were disconnected, not in the signal path durning measurement.

Okay, what you have done is not suggested, you could possibly damage the amp that way.
You need a load on the amplifier to do the voltage measurement, either the speakers or a 4 or 8 Ohm dummy load.

With the speakers connected and your test tone on, measure the voltage at full gain across the speaker terminals (you might need ear protection) Divide the measured voltage by two and square the result, divide this by the speaker impedance this will give you a pretty good idea of the output wattage. (for example: 40V / 2 = 20, 20 x 20 = 400 / 8 = 50

Good to know. Just measured the voltage at speaker binding posts (with speakers connected). Still using a 440 Hz test tone.

H50, 4 ohms setting, 100% volume ==> 2.328v (vs 2.384v last time)
H50, 8 ohms setting, 100% volume ==> 2.323v (vs 2.385v last time)

Virtually identical readings from last time. And also virtually identical readings for 4 ohms and 8 ohms. Let me round all the numbers up to 2.4v

First, is dividing 2.4 by 2 necessary?

Even without dividing 2.4 by 2,

H50 Power (RMS) = (2.4v x 2.4v) / 8 ohms = 0.72w (this number seems low, something is wrong, please help.)

If we put the wattage aside, shouldn’t I get a different voltage readings for 4 ohms and 8 ohms. Why are they the same?

If I put the output wattage calculation aside, according to H50 specification, it has two modes:
2x30W @ 8ohm load at 24V
2x50W @ 8ohm load at 24V(Boost)

How do I configure H50 to have different output levels?


What LUFS value does Arylic target to adjust maximum output wattage the various inputs? Is Bluetooth set the same as Optical, DAC etc? In my experience there are significant differences and hence the need for adjustments.

Most streaming services target -14 LUFS so this would be a reasonable level for 95% max output wattage?
If you don’t trust users to understand clipping and thermal overloading, then can DRC be implemented?