Review and Measurements of Schiit Aegir PWR Amplifier

[JohnBooty]

Class B has clear discontinuity as one transistor gets biased with the other one not working. That gap is compensated in class AB by pre-biasing the two transistors so that they can hand off to each other quickly. That compensation is simple and hence the reason there is no such thing as class B audio in the market.

Class A's advantage is simplicity in circuit design. When transistors were expensive and so was labor, having an amplifier with half the parts was an advantage. That has not been the case for decades. The efficiency advantage of class AB has obsoleted class A in audio for years.

Thank you for the excellent explanation. I truly learned something here. =)

Though you heard no difference, is there a theoretical benefit to what Schiit claims to have done here, with extending Class A biasing up to 10W or whatever?

 

[restorer-john]

The efficiency advantage of class AB has obsoleted class A in audio for years.

Class A amplifiers are great in winter for heating up your listening room.

 

[amirm]

Though you heard no difference, is there a theoretical benefit to what Schiit claims to have done here, with extending Class A biasing up to 10W or whatever?

In theory, class A can have lower distortion if exceptionally well implemented. If so, that benefit will extend to higher power as they claim. This amplifier is not exceptionally well engineered as we see from measurements. So there is no real benefit that I see.

 

[amirm]

I would love to see the harmonic distortion product ratio if you have the time. It would be extra awesome if you could provide the the raw FFT (to check for Power Supply related products) AND the AP Distortion Product Ratio: https://www.ap.com/blog/thd-and-thdn-similar-but-not-the-same/

Raw FFT was in the dashboard and it does show all the power supply related components.

Here is the distortion product ratio:

It is at 5 watt using 1 kHz.

As to running it all the time, every new test I add slows my throughput of producing more reviews. Above display doesn't tell me anything other than what I see in the FFT in the dashboard. Indeed, it shows less by discarding everything else. So while it is prettier to look at, I don't know that it is worth spending the time on it all the time.

 

[amirm]

View attachment 35515
Why is there a broadening around the 1kHz test tone?

I zoomed way in using higher resolution FFT and no longer see that:

The lower resolution of the FFT in the dashboard may ave combined the distinct tones you see now to combine with noise to generate that shape.

 

[audimus]

For decades now, it seems to be accepted fact that Class A amplification sounds better. Of course, it's horribly inefficient, unlike Class B amplification.

That's why, for many decades, Class AB amplification was the dominant technology. The first N watts are Class A (because it sounds better) and the rest are Class B (because it doesn't heat your entire house).

In a traditional Class AB amp, only the first watt or two (IIRC) are Class A. What Schiit is claiming here is that the technology in their Aegir extends the Class A biasing up to 10W or so. That is not "tech porn", or mumbo jumbo. That is some pretty basic "amplification 101" talk.

Wow. Here on ASR -- a community dedicated to truth and honesty in audio -- we hate Schiit so much that we're now blasting them for.... truth and honestly? Laughable. We're better than that. Imagine the hatred if they weren't up-front about how hot the dang thing runs. There are plenty of reasons to criticize Schiit and others; let's not criticize them for transparency.

This amp may be a lousy product, or it may be something you'd enjoy, but whatever the case we should not be ripping a company for honesty.

(FWIW, I don't have a horse in this race. I don't own an Aegir and have no plans to buy this or any other amp in the near or even medium future...)

You misunderstand my reason for bringing that up. The reputation of Schiit is that they are better marketeers than device builders to foist some of their bad equipment on consumers. If that reputation was deserved, then they would not be putting out such statements like it will still run hotter. So, my conclusion is that instead they are actually techy-geek but marketing idiots (which does not require full transparency) and just happened to find a target consumer segment for whom that technical mumbo jumbo takes precedence over what it actually means in practice. It is not ripping the company but rather some views of this company as good marketeers as an explanation for their commercial success so far.

 

[gvl]

Speaking of Yamaha amps and class A, their 88/89 MX lineup featured Hyperbolic Conversion Amplification Circuit (HCA) which was said to provide class-A like linearity across full power-band without the class-A heat. Perhaps the Aegir is a similar design?

 

[restorer-john]

Speaking of Yamaha amps and class A, their 88/89 MX lineup featured Hyperbolic Conversion Amplification Circuit (HCA) which was said to provide class-A like linearity across full power-band without the class-A heat. Perhaps the Aegir is a similar design?

Putting a Schiit Aegir in the same sentence as an MX-600/800/1000 is not fair on the Yamahas...

No comparison:

(my scans)

Specs. I have an MX-600 here, it's an incredibly quiet amplifer (hiss). 16uV residual.

And here, just for fun, here is the matching CX-1000 preamplifier. A lesson in how to build a preamplifier in 1989. Onboard D/A converter too.

The design aesthetic unfortunately hasn't stood the test of time. Yamaha mixed jutting angles with clean lines, something they fixed in the next series, the MX-630/830 range of 1990/1. It had slightly rounded panel tops and bottoms, softer controls and a way nicer look. Trouble is, the performance took a hit.

 

[gvl]

MX-600U here too in a "desk amp" duty, well, rather "under desk" hehe. Works fine but one channel is weaker until warmed up, increasing input level helps to wake it up too. Likely after 30 years it's time to track down some dried caps.

 

[restorer-john]

MX-600U here too in a "desk amp" duty, well, rather "under desk" hehe. Works fine but one channel is weaker until warmed up, increasing input level helps to wake it up too. Likely after 30 years it's time to track down some dried caps.

Speaker relay likely needs replacement. It's common when the plated contacts oxidize. The volume burst overcomes the oxide layer on one set of the contacts. As the relay warms up (the coil) the yoke pushes the contact bar slightly harder against the contact points.

To confirm, firmly tap the top of the relay with a wooden chopstick (safety distance and short circuit proof) when the signal is "weaker" (powered on) and report back. The Yamaha relays can be removed and dismantled (cover popped off) to clean the contacts (1000+ grit wet and dry paper strip) or simply replaced. Do not go poking around changing capacitors, that will be a waste of time and money.

Also, check the speakers A and B switches as the switching is after the relay. If the problem is not present on speaker B the push switches on Spk A have also oxidized.

 

[gvl]

Speaker relay likely needs replacement. It's common when the plated contacts oxidize. The volume burst overcomes the oxide layer on one set of the contacts.

To confirm, firmly tap the top of the relay with a wooden chopstick when the signal is "weaker" (powered on) and report back. The Yamaha relays can be removed and dismantled (cover popped off) to clean the contacts (1000+ grit wet and dry paper strip) or simply replaced. Do not go poking around changing capacitors, that will be a waste of time and money.

Thanks for the hint. My hunch it is not the relay as the channel is just less loud and not crackling, also the volume restores smoothly not abrupt which is typical for bad continuity in relay contacts and such, but I will surely check the relay, just need to find the time... One of the small caps looked leaky when I popped the cover last time, need to poke around. I have a similar problem on a Denon POA-6600 and there it does sound like the speaker relay, uneven low volume sound with some distortions, raising level helps to clear it.

 

[maty]

I have waited a few hours if someone.... Class A amplifier up to 10 watts I think but fat electrolytic capacitors of only 85° C and they are near from the power transistors. The wiring

 

[w1000i]

@amirm Is it possible to measure the current ( I ) capability of an amplifier ?

 

[maty]

https://www.schiit.com/products/aegir

Continuity™: Benefits Beyond Class A

Aegir is our first Continuity speaker amplifier, extending a technology we introduced with the Lyr 3 headphone amp. Technically, Continuity is a way to eliminate transconductance droop outside of the Class A bias region, and extend the benefits of Class A biasing. It also solves the NPN and PNP device mismatch problem, since it uses both NPN and PNP devices on both rails. It’s still a very hot-running amp, though, with over 10W of Class A standing bias.

10 watts x2 = 20 watts. Class A has efficiency between 15-20% -> 20 watts x6 = 120 watts.

 

[restorer-john]

Is it possible to measure the current ( I ) capability of an amplifier ?

Ask Ray. I think he uses his Krell for weekend welding jobs around the home.

 

[Juhazi]

Stereophile tested Aegir too https://www.stereophile.com/content/schiit-audio-aegir-power-amplifier
-
What makes the Schiit Audio Aegir so special is how it generates class-D-like force and clarity plus the information-dense refinements of class-A. -Herb Reichert

I was pleasantly surprised by the Schiit Aegir's measured performance. It is a well-engineered amplifier at an affordable price.—John Atkinson

 

[Willem]

Which goes to show....

 

[w1000i]

Ask Ray. I think he uses his Krell for weekend welding jobs around the home.

Hahaha. My concern if a speaker with many drivers with big voice coil but high sensitivity compare to other speaker with less drivers same sensitivity.

Is there any limit with low watt amplifier ( low current !! ) ?

 

[anmpr1]

Basically, the A-S701 is a 1991 AX-570 with a single board D/A converter jammed in (on top of the main filter caps...), electronic input switching and a cosmetic makeover.

It might be 'basically' the same. However Yamaha has a history of making electrical changes between models, sometimes not beneficial to the newer 'designs'. See David Rich's review of the successor to the AS-570, the AS-592, in Issue 25 of Audio Critic (available on-line somewhere).

I think you are likely correct, overall. If someone is looking for a pretty good integrated amp at a pretty good price, with a pretty good DAC inside, it will probably be hard to beat the Yamaha. At least that is my impression from their history, and not having any good review data to go by.

Disclaimer: I own an AS-592 I bought new (I think it was $500.00). I don't use it anymore, but could. It's held up well.

 

[restorer-john]

Disclaimer: I own an AS-592 I bought new (I think it was $500.00). I don't use it anymore, but could. It's held up well.

AX-592. Same heritage, but from the era where they made flaps to cover "rarely" used controls.

Another good mid range amplifier from Yamaha.

My concern is the D/A in the unit mentioned is just stuck there, little care for shielding, placement and I expect its ultimate perfomance will be average.