Apollon 1ET6525SA ST Amplifier Review

[Apollon Audio]

That makes sense ... would you be willing to offer a regulated MicroAudio power supply option?

Micro Audio power supplies, like most SMPS solutions used in high-power audio amplifiers, do not employ tightly regulated high-voltage rails for the output stage. Instead, they provide an unregulated (or loosely regulated) high-voltage DC bus whose voltage varies with mains input voltage and load conditions.

 

[JeremyFife]

Thanks Amirm (again!). Cracking amp, not much more to say

 

[delta76]

Am I missing something? This is supposed to be the successor to the 1ET400A but it’s down on power on that older model and on the newer 1ET6525SA spec?

E.g. NAD 298 1ET400A design: 187w into 8ohm, 345w into 4ohm

This unit: 158w 8ohm, 276w 4ohm, 367w 2ohm

1ET6525SA spec is 230/450/510w, respectively. Why is the Apollon so far off?

If you compare module by module, then this has more power (just slightly) and has less noise/distortion. However it depends on actual implementation (PSU etc.)

 

[Steakhouse]

Smells like endgame again.

 

[Apollon Audio]

If you compare module by module, then this has more power (just slightly) and has less noise/distortion. However it depends on actual implementation (PSU etc.)

The measured output power can vary depending on the available mains input voltage. When the amplifier is supplied with a lower mains voltage (for example 110-120V), the Hypex 1200/A400 switched-mode power supply provides a correspondingly lower DC rail voltage, which results in a slightly reduced maximum output power.

This behavior is common to most SMPS-based power supplies, as their maximum available output power is directly influenced by the mains input voltage. At higher mains input voltages (such as 240-250V in Europe or 130 V on a high-line U.S. supply), the power supply delivers the nominal DC voltage required for the amplifier to reach its specified output of 425 W into 4 Ω. Here in Europe this amp measures slightly better.

 

[delta76]

Guess it’s a choice between this one and Boxem (has autosensing and auto-off), in case you stay in Europe at least.

And audiophonics.
But admittedly i prefer this amp design better than audiophonics one. Price is better too

 

[Jukka]

@Apollon Audio If I were to use a power strip, that has power switch, to power on/off all my gear, does this amplifier have a "always on" power button or do I need to press it each time when power is on? Rocker switches usually stay in their position, but I cannot tell about these push buttons without trying.

In fact I have set up my main system to be powered on in stages. There is a signal sensing automatic part for every day use, and then there are the added woofers and subwoofers that are switched on by power strips. It would help the already complex system if the amp was "always on", but that's not a deal breaker.

 

[milanjeromos]

This is a review and detailed measurements of the Apollon 1ET6525SA ST Purifi based class D stereo power amplifier. It was kindly loaned to me by a member and costs 1,190.00€ (USD $1,348).
View attachment 503302
Apollon designs are unique a step up from some of its competitors. Even the power switch feels nice and has niceties such as settable brightness:
View attachment 503303
That premium extends to no less than four gain settings (although I had trouble reading the tiny fonts). Not only do we have trigger input but also output!

In use, the top of the amp was room temperature and bottom only slightly above.

Apollon 1ET6525SA ST Amp Measurements
To keep me from going crazy, I focused my testing on XLR input only. For gain, I started with the lowest gain setting of 12.X:
View attachment 503304
This performance easily lands the amp into top 20 amplifiers ever tested (out of nearly 300):
View attachment 503305
Naturally, higher gain settings rob you of some performance but not much at 20.X:
View attachment 503306
Going to 27 does cost you though in noise department:
View attachment 503307

Fortunately 20 dB gain is good enough to push the amp to max power with nominal 4 volt input over XLR connection:
View attachment 503308

If you have a professional interface that can output more than 9 volts, you can opt to use the lowest gain:
View attachment 503309

From here on, I focused on testing at 20 dB.

Frequency response is load independent as we expect in this class of class D amps:
View attachment 503310

Multitone and 19+20 kHz show superbly low intermodulation distortion:
View attachment 503311
View attachment 503312
Lower class class D amps really suffer in the above test. Not so here, leaving many class AB amps in the dust.

Channel isolation is superb as well:
View attachment 503313

Available power in the sweet spot of what I recommend:
View attachment 503314

View attachment 503315
And doesn't change much in bass either:
View attachment 503316

8 Ohm naturally has less power but most speakers are 4 ohms or lower:
View attachment 503317

I tested its ability to drive one channel with 2 ohm. While it did that superbly, it did not result in a lot more power:
View attachment 503318

Our sweeps with respect to frequency show the common rise in distortion at higher frequencies. But this is still excellent performance:
View attachment 503319

Power on noise is nonexistent but there may be noise on power off:
View attachment 503320

Finally, the amp is rock solid on power up:
View attachment 503322

Conclusions
The Apollon 1ET6525SA ST is a solid offering in premium module based amplifiers. It has done justice to the underlying Purifi module by providing superbly low noise and distortion. It has rich feature set in the form of gain setting, trigger, etc. With almost every speaker being happy with nearly 400 watts on tap, it makes for an easy and future proof choice. And a feature in the cap of our European members!

I am happy to recommend the Apollon 1ET6525SA ST amplifier.
-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

This is a review and detailed measurements of the Apollon 1ET6525SA ST Purifi based class D stereo power amplifier. It was kindly loaned to me by a member and costs 1,190.00€ (USD $1,348).
View attachment 503302
Apollon designs are unique a step up from some of its competitors. Even the power switch feels nice and has niceties such as settable brightness:
View attachment 503303
That premium extends to no less than four gain settings (although I had trouble reading the tiny fonts). Not only do we have trigger input but also output!

In use, the top of the amp was room temperature and bottom only slightly above.

Apollon 1ET6525SA ST Amp Measurements
To keep me from going crazy, I focused my testing on XLR input only. For gain, I started with the lowest gain setting of 12.X:
View attachment 503304
This performance easily lands the amp into top 20 amplifiers ever tested (out of nearly 300):
View attachment 503305
Naturally, higher gain settings rob you of some performance but not much at 20.X:
View attachment 503306
Going to 27 does cost you though in noise department:
View attachment 503307

Fortunately 20 dB gain is good enough to push the amp to max power with nominal 4 volt input over XLR connection:
View attachment 503308

If you have a professional interface that can output more than 9 volts, you can opt to use the lowest gain:
View attachment 503309

From here on, I focused on testing at 20 dB.

Frequency response is load independent as we expect in this class of class D amps:
View attachment 503310

Multitone and 19+20 kHz show superbly low intermodulation distortion:
View attachment 503311
View attachment 503312
Lower class class D amps really suffer in the above test. Not so here, leaving many class AB amps in the dust.

Channel isolation is superb as well:
View attachment 503313

Available power in the sweet spot of what I recommend:
View attachment 503314

View attachment 503315
And doesn't change much in bass either:
View attachment 503316

8 Ohm naturally has less power but most speakers are 4 ohms or lower:
View attachment 503317

I tested its ability to drive one channel with 2 ohm. While it did that superbly, it did not result in a lot more power:
View attachment 503318

Our sweeps with respect to frequency show the common rise in distortion at higher frequencies. But this is still excellent performance:
View attachment 503319

Power on noise is nonexistent but there may be noise on power off:
View attachment 503320

Finally, the amp is rock solid on power up:
View attachment 503322

Conclusions
The Apollon 1ET6525SA ST is a solid offering in premium module based amplifiers. It has done justice to the underlying Purifi module by providing superbly low noise and distortion. It has rich feature set in the form of gain setting, trigger, etc. With almost every speaker being happy with nearly 400 watts on tap, it makes for an easy and future proof choice. And a feature in the cap of our European members!

I am happy to recommend the Apollon 1ET6525SA ST amplifier.
-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Miss the videos Amir, especially the technical stuff!

 

[sabih]

I think hifi is reaching at its peak.
Our future generations will never know the struggles to find the best amp.
They will assume that amplifier technology has always been perfect.
They will laugh at us for being too obsessive about audio.

 

[Sokel]

I think hifi is reaching at its peak.
Our future generations will never know the struggles to find the best amp.
They will assume that amplifier technology has always been perfect.
They will laugh at us for being too obsessive about audio.

Amplification is a solved problem for decades, it's only cheaper now.
What reached its peak (almost) is nice engineering of class D amps.

 

[unmutual]

@Apollon Audio If I were to use a power strip, that has power switch, to power on/off all my gear, does this amplifier have a "always on" power button or do I need to press it each time when power is on? Rocker switches usually stay in their position, but I cannot tell about these push buttons without trying.

In fact I have set up my main system to be powered on in stages. There is a signal sensing automatic part for every day use, and then there are the added woofers and subwoofers that are switched on by power strips. It would help the already complex system if the amp was "always on", but that's not a deal breaker.

I use a power strip with switch to power my system on / off. I don't have to turn the Apollon amp on when I do this.

 

[amirm]

@Apollon Audio If I were to use a power strip, that has power switch, to power on/off all my gear, does this amplifier have a "always on" power button or do I need to press it each time when power is on? Rocker switches usually stay in their position, but I cannot tell about these push buttons without trying.

The on off switch is mechanical so you can indeed turn it on off with power strip.

 

[Fletcher Munson]

Nice review,

I just ordered a purple one using the Christmas coupon code XMAS25, 1167.73€ delivered to the UK

Fingers crossed, it will be my first big class-D

 

[Fletcher Munson]

Its going to replace my PA5 II+ driving my B&W Matrix 800. At last.

 

[KxDx]

And audiophonics.
But admittedly i prefer this amp design better than audiophonics one. Price is better too

I have the Apollon 1ET400SA amp and an Audiophonics LPA-S400ET "Shoebox" with the same modules. The Apollon is such a looker!

 

[dan_uk]

@Apollon Audio If I were to use a power strip, that has power switch, to power on/off all my gear, does this amplifier have a "always on" power button or do I need to press it each time when power is on? Rocker switches usually stay in their position, but I cannot tell about these push buttons without trying.

In fact I have set up my main system to be powered on in stages. There is a signal sensing automatic part for every day use, and then there are the added woofers and subwoofers that are switched on by power strips. It would help the already complex system if the amp was "always on", but that's not a deal breaker.

I've got a HCx500 from Nord, and I have it plugged into a smart plug that is scheduled to turn off every day at mid night and then again at 7am... Then whenever I want to listen to music, I ask Alexa to turn on my power amp. The trigger from my DAC isn't a standard 12v so doesn't play nicely (Matrix Audio).

 

[CD2]

That was great, especially reading across several recent reviews. Have to say when I first found this site the reviews were a bit hard to follow, but after you read a bunch and work out the writer's logic they're highly lucid.

 

[Vincentponcet]

One more great alternative.
However, Boxem shouldn't be worried IMO when it comes to overall implementation and thought-out usability.

I don't like autosensing since that doesn't match my listening habits with plenty of breaks and resumptions at all. - That's the deal breaker to me.

And I know about that type of flimsy input switch very well... At least we did not receive a dip switch panel, that's the good news...
If you don't insert your tool, like a 3mm slotted screw driver super carefully and strictly vertical...with every switching operation that black hard plastic would get deformed just a little bit more, and over time it would really suffer from wear. - If you don't do a lot of swapping, switching and testing that's not an issue for sure...

I use the trigger from the AVR, works perfectly.

 

[delta76]

That was great, especially reading across several recent reviews. Have to say when I first found this site the reviews were a bit hard to follow, but after you read a bunch and work out the writer's logic they're highly lucid.

Yes the graphs can be overwhelming. Even scary to look at (speaker measurements, after 4y on this forum I still oblivious)
But if you look for panther one and the quick comments on each graph it is easy to follow. I have made a myself a rule, if it is not at least happy panther I will not read the review in detail (if at all) Life is too short to pay attention to bad products when you have many better ones to consider

 

[Timcognito]

Thanks Amir. I guess you are getting some reviews in with the Seattle US Football team two week layoff.