# Amps: class GH vs class AB



## 000zero (Mar 12, 2011)

So I am searching for my next amp and was considering one from the Arc Audio KS series, which is a class GH amplifier. I really wanted to try a class AB because I have never had one before and was curious. I was talking to my local dealer and he was pushing hard for the class GH saying it was the latest and greatest. What are the differences between the two?

I read that a GH is supposed to have the clean sound of an AB but with the efficiency of class D. What do you DIY'ers think?


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## BowDown (Sep 24, 2009)

I would say it's all smoke and mirrors.. but seriously I have never pulled a classAB and replaced it with a GH. I have however heard a setup with Arc GH series amps on everything and it is damn clean. 

Take it for what it's worth though.


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## 000zero (Mar 12, 2011)

Thanks for the input. I think a side by side comparison awesome, has anyone listened to both of these types of amps?

I am mostly interested in if the SQ of the two topologies would comparable, or is class AB still way above the GH class.


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## ChrisB (Jul 3, 2008)

I used the Clarion DPX1851 which is the Ubuy equivalent of Arc minus a few bells and whistles. I wouldn't say it's efficiency is on par with class d, but it is much better than ab, especially ab lower volumes. I always make the old schoolers mad, but my DPX1851 was way easier on my custom electrical system than the boneriffic Linear Power 5002 that I used to power my 13w6v2 with. 

Same sub, same car, different amps, different impedances with coils in series for the ab amp versus parallel for the class gh amp, less strain on my custom built alternator and no discernible difference in sound quality. YMMV if you buy into marketing hype and buzz words that will undoubtedly cause a psychoacoustic effect.


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## 000zero (Mar 12, 2011)

Well at least it looks like my dealer had a valid reason to push the Arc Audio KS 300.4 so hard.


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## ChrisB (Jul 3, 2008)

Think of Class GH like this... It's basically a Class AB amplifier with a switching power supply. My suggestion would be to listen to them on your dealer's sound board. I highly doubt you will be able to tell a difference between GH and pure AB.


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## 000zero (Mar 12, 2011)

Oddly enough the dealer I usually go to has pretty no demo boards set up, yet it's one of the top shops in southern cali. So I will have to find another dealer before I can listen to both types. The info on this thread so far has helped me form a better opinion on which amp I want now.


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## WLDock (Sep 27, 2005)

One would think amps in general don't sound much different at normal levels. Also, Class GH amps IMO would seem as if they would have similar characteristics to class AB amps. However, here recently I found it hard to believe that a HERTX EP2x class AB amp sounded much different than a Clarion DPX2251 class GH amp...the sound of the HERTZ seem to anchor the stage in a nicer way.

http://www.diymobileaudio.com/forum...dible-physics-ar3k-vs-tangband-w3-1878-a.html

For the record I plan to run this test again....just for my own curiosity. I was looking for more reviews on the HERTZ amp and found a foreign review that compares the:

JL 300/4
Hertz EP4
DLS RA 50
Clarion APX4361

teste de amps - AutoForum.com.br - Página 3 (Use Google Translate)

The reviewers seems to like the DLS then the Clarion APX4361 (Class AB) over the others for the most part. I would like to run my own amp test comparing these:

CLARION APX4361 (class AB)
CLARION DPX2251 (class GH)
DLS A4 (class AB)
HERTZ EP2x (Class AB)

Then there are amps like the JL Audio HD & XD as well....would like to add one of those to the mix. Will see....but I have no doubt that different brands and topologies might sound different to some.


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## 000zero (Mar 12, 2011)

WLDock said:


> One would think amps in general don't sound much different at normal levels. Also, Class GH amps IMO would seem as if they would have similar characteristics to class AB amps. However, here recently I found it hard to believe that a HERTX EP2x class AB amp sounded much different than a Clarion DPX2251 class GH amp...the sound of the HERTZ seem to anchor the stage in a nicer way.
> 
> http://www.diymobileaudio.com/forum...dible-physics-ar3k-vs-tangband-w3-1878-a.html
> 
> ...


If you ever do run those tests I would be interested in your results.

Well I think have decided to go after the Arc KS 300.4, I would like a 6 channel amp but it has to be able to fit under my seat so that leaves me with no options there. From the responses above class GH amps are at least worth trying and since I don't want to do anything to my electrical system the efficiency of the GH seems like a good fit. Also the price of the KS is achievable compared to the 6 channels I have found.

Thank you to everyone who posted info, if there are any other amps you guys think I should be considering please let me know.


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## kvndoom (Nov 13, 2009)

I liked the build and sound of the 300/4 far more than the APX4361. To each his own, I guess.


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## WLDock (Sep 27, 2005)

kvndoom said:


> I liked the build and sound of the 300/4 far more than the APX4361. To each his own, I guess.


Yeah, the JL's are solid amps...never had issues with them.....Again...I think it goes to show that some can hear differeces between not only class AB, GH, and D but class AB vs. class AB. 




000zero said:


> If you ever do run those tests I would be interested in your results. Well I think have decided to go after the Arc KS 300.4, I would like a 6 channel amp but it has to be able to fit under my seat so that leaves me with no options there. From the responses above class GH amps are at least worth trying and since I don't want to do anything to my electrical system the efficiency of the GH seems like a good fit. Also the price of the KS is achievable compared to the 6 channels I have found. Thank you to everyone who posted info, if there are any other amps you guys think I should be considering please let me know.


In terms of 6 channels in a small space....The JL Audio XD600/6 (NexD™ Class D) is hard to beat....10.23"L x 7.09"W in. x 2.05"H in. will fit under many seats...have seen them as low as $350.
Also, the 6 channel SOUNDSTREAM STEALTH STL6.620 is actually a class AB amp! - 11.25"L x 6.5"W x 2.125"H Soundstream - Stealth Amplifiers under $250 at buy.com and amazon.com


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## 000zero (Mar 12, 2011)

Wow that soundstream stealth amp looks like a great option thanks for that suggestion. How would you guys say soundstream amps compare to say arch audio or hertz amps?


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## kvndoom (Nov 13, 2009)

WLDock said:


> Yeah, the JL's are solid amps...never had issues with them.....Again...I think it goes to show that some can hear differeces between not only class AB, GH, and D but class AB vs. class AB.


Indeed... the topology isn't the only thing that matters. The quality of the components in every stage plays some part in the overall sound.


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## 000zero (Mar 12, 2011)

kvndoom said:


> Indeed... the topology isn't the only thing that matters. The quality of the components in every stage plays some part in the overall sound.


Thats what I'm worried about, the soundstream STL6.620 has everything I want, Class AB, 6 channels, enough power, small footprint and its pretty affordable, but I want as much SQ as I can get. I know Arc amps are solid, proven performers so I wonder if I will miss anything if I get the STL6.620 instead of the KS300.4.


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## Jsracing (Apr 1, 2011)

Some have said the lower SS amps are a bit over rated on power. Another AB option for you is the Massive NX5. It's quite small also.
I heard the Arc ks300.4 with some Rainbows and it sounded really clean. The output stage is stl AB on the GHs, it's only the power supply end that's different. The GHs offer better efficiency when youre not operating at full poorer, which is most, if not all, the time. Their not a efficient as D, but you gain about 10% efficiency. 
I have a JL XD700/5 myself and think it sounds great. It fits under my seat and barely gets warm when I'm balding it for a couple of hours straight. During normal use, it stays cool.
Of you're open to full range class Ds, also consider the upcoming PPI Phantom series. They should be lower cost than the JL XDs, though no one knows of they wil have the occasional noise issues like the Arc XXDs.


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## WLDock (Sep 27, 2005)

000zero said:


> Thats what I'm worried about, the soundstream STL6.620 has everything I want, Class AB, 6 channels, enough power, small footprint and its pretty affordable, but I want as much SQ as I can get. I know Arc amps are solid, proven performers so I wonder if I will miss anything if I get the STL6.620 instead of the KS300.4.


The only way for you to really know is to compare them yourself....
*However here is one person's review: *http://www.diymobileaudio.com/forum...undstream-stealth-amps-my-initial-review.html

*Pictures of the internals:*
http://www.diymobileaudio.com/forum...maller-than-alpine-pdx-anyone-use-them-4.html

*Manual:*
http://www.soundstream.com/manuals/2009/SS_2009 Stealth Series Amplifiers.pdf


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## trojan fan (Nov 4, 2007)

Vibe Litebox, class GH, same amp as the Arc but half the price


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## 000zero (Mar 12, 2011)

Jsracing said:


> Some have said the lower SS amps are a bit over rated on power. Another AB option for you is the Massive NX5. It's quite small also.
> I heard the Arc ks300.4 with some Rainbows and it sounded really clean. The output stage is stl AB on the GHs, it's only the power supply end that's different. The GHs offer better efficiency when youre not operating at full poorer, which is most, if not all, the time. Their not a efficient as D, but you gain about 10% efficiency.
> I have a JL XD700/5 myself and think it sounds great. It fits under my seat and barely gets warm when I'm balding it for a couple of hours straight. During normal use, it stays cool.
> Of you're open to full range class Ds, also consider the upcoming PPI Phantom series. They should be lower cost than the JL XDs, though no one knows of they wil have the occasional noise issues like the Arc XXDs.


thanks for the info, I currently have a full range class D amp so I'm looking to try something different.


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## 000zero (Mar 12, 2011)

trojan fan said:


> Vibe Litebox, class GH, same amp as the Arc but half the price


What do you mean same amp? Same exact internals? Same specs? Same design, but cheaper components?


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## ChrisB (Jul 3, 2008)

000zero said:


> What do you mean same amp? Same exact internals? Same specs? Same design, but cheaper components?


Same board design with some fundamental differences. The Vibe has the controls accessible from the bottom of the amplifier whereas the Arc has them accessible from the top. I want to say the capacitors were different between the Vibe and the Arc too, but don't quote me on that one. 

Even my $150 Clarion DPX1851 was similar to one of the Arc Audio offerings, but I can't remember which one. Regardless for a $150 subwoofer amplifier that came with a 2 year warranty, I really did not care.:laugh:


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## 000zero (Mar 12, 2011)

ChrisB said:


> Same board design with some fundamental differences. The Vibe has the controls accessible from the bottom of the amplifier whereas the Arc has them accessible from the top. I want to say the capacitors were different between the Vibe and the Arc too, but don't quote me on that one.
> 
> Even my $150 Clarion DPX1851 was similar to one of the Arc Audio offerings, but I can't remember which one. Regardless for a $150 subwoofer amplifier that came with a 2 year warranty, I really did not care.:laugh:


It would be interesting to hear a comparison between the two as far as SQ goes, if anyone has done such a comparison I would appreciate your feedback.


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## trojan fan (Nov 4, 2007)

000zero said:


> It would be interesting to hear a comparison between the two as far as SQ goes, if anyone has done such a comparison I would appreciate your feedback.



Sound is a very subjective matter, but IMO I could not tell a difference


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## ryan s (Dec 19, 2006)

It's 2011...the "true believers" can have the ABs...take them all. Buy the 3 I have, please :laugh: Can't wait to get some GHs in my car. Alternate topologies are no longer "new" tech and plenty of people have used full-range D and GH to great acclaim...so why wait any longer to make the jump? Efficiency _and_ low current draw _and _small size _and _high power _and _SQ? 

Listening at half volume while parked for 10 minutes--and 20 minutes at volume 7 *or less *with a lot of that time selecting songs--*two songs at medium volume* is enough to run down my new battery far enough to require a jump  85A of fusing so it's not some megawatt set up. The battery is a group 34 so it isn't a little mini start-only cell...


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## ChrisB (Jul 3, 2008)

ryan s said:


> It's 2011...the "true believers" can have the ABs...take them all. Buy the 3 I have, please :laugh: Can't wait to get some GHs in my car. Alternate topologies are no longer "new" tech and plenty of people have used full-range D and GH to great acclaim...so why wait any longer to make the jump? Efficiency _and_ low current draw _and _small size _and _high power _and _SQ?
> 
> Listening at half volume while parked for 10 minutes--and 20 minutes at volume 7 *or less *with a lot of that time selecting songs--*two songs at medium volume* is enough to run down my new battery far enough to require a jump  85A of fusing so it's not some megawatt set up. The battery is a group 34 so it isn't a little mini start-only cell...


I couldn't agree more. The old school, living in the past, die hards can keep their inefficient amplifiers that require 1/2 a trunk of mounting area to power a modest system. I'll take smaller, more efficient amplifiers offered today. 

In fact, I am seriously considering having one last sale and going with a single JL Audio HD900/5 in my vehicle. I almost listed a for sale ad TWICE this week!


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## Jsracing (Apr 1, 2011)

Regarding the Vibe Litebox, the only differences from the Arc is several of the input filter caps are slightly smaller and some other caps used further in the amp use a different package. Looks to be a great amp, but a class D is still considerably more efficient so the full range class D won me over. So far im extremely happy with my D, but am curious to try a GH.


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## 000zero (Mar 12, 2011)

Another difference between the litebox and the arc is the arc can crossover up to 5k, while the litebox can only go up to 500 Hz


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## Jsracing (Apr 1, 2011)

The Litebox compares to the ks125.4 which I don't think has that high a filter. The ks300.4 does but its a different product.


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## Eric Stevens (Dec 29, 2007)

000zero said:


> So I am searching for my next amp and was considering one from the Arc Audio KS series, which is a class GH amplifier. I really wanted to try a class AB because I have never had one before and was curious. I was talking to my local dealer and he was pushing hard for the class GH saying it was the latest and greatest. What are the differences between the two?
> 
> I read that a GH is supposed to have the clean sound of an AB but with the efficiency of class D. What do you DIY'ers think?


Class G or H in an oversimplified statement are Class AB amplifiers with variable power supply voltage rails. All modern amplifiers utilize switching power supplies.

A Class AB amplfier reaches maximum efficiency at full power, in fact Class AB are just as efficient as a Class D amplifier at full power. Only advantage for the Class D is below full power its efficiency only drops a little.

A very simplified explanation of Class G or H is that they vary the power supply rail voltages so that the amplfier is effectively at or near full power at most power levels.

So a Class G or H amplfier should sound equal to a Class AB amplfier if they have comparable quality of design and components.

Eric


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## 000zero (Mar 12, 2011)

Thanks to everyone for the info, I have decided to go after the Arc Audio KS 300.4. Need to save up some chips first though, when I get it I will post what I think about it.


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## 000zero (Mar 12, 2011)

I got the KS300.4 and have had it hooked up for a about a week now and I would say it is definitely a good improvement over the XXD 4080. The rest of my setup stayed the same so it was basically an side by side comparison, I can hear more detail and the music seems a bit more airy (not sure if that is the word I am looking for). My L1V2 are singing nicely now, they are some amazing tweets. I couldn't fit my memphis X-over under the seat anymore so I am just using the crossover on the KS for now so I have some freq overlap between my mid and mid-bass, I think I will improve the clarity in the mid frequencies once I figure out a way to fit the x-over under the seat. I was thinking of maybe getting a piece of 1/4 MDF and raising one side up and placing it so it is slightly overlapping with the KS, there is a lot of vertical space under my seat so I think this could work.


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## ryan s (Dec 19, 2006)

Sell that non-SQ XXD to me for dirt cheap, since it sounds so bad :laugh:

By the way, your auditory memory is like 30 seconds (or less) and I didn't see a mention of gain-matching...psychoacoustics at work.

But Zeff amps ftw in any case


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## 000zero (Mar 12, 2011)

ryan s said:


> Sell that non-SQ XXD to me for dirt cheap, since it sounds so bad :laugh:
> 
> By the way, your auditory memory is like 30 seconds (or less) and I didn't see a mention of gain-matching...psychoacoustics at work.
> 
> But Zeff amps ftw in any case


Where did I say it sounded bad? I didn't say anything about gain matching because I didn't think it needed to be said, to me its common sense; if you hook up a new amp you set the gains. I know how loud my stereo is supposed to be at given volume level on my HU because I have been listening to it for 3+ hours a day for about a year. So I'm pretty confident my gains are ok.

As for the auditory memory thing your probably right, but I have listened to my own set of reference songs over and over with the XXD and I listened to those same songs over and over with the KS now, its that comparison that I am using to say that it sounds 'better'. So I don't think its psychoacoustics at work I think its my taking the time to do my own comparisons with my own reference songs. So maybe next time you should ask some questions before you make assumptions.

Btw you can sell me your Zeff amp for dirt cheap because its just psychoacoustics at work anyway


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## ryan s (Dec 19, 2006)

The thing is, though, people *always *have a better result when they swap equipment...isn't it funny like that? 

Since a good chunk of amp buying is psychoacoutics, I don't spend more than necessary. And Zeff amps are great since they're available in cheaper heatsinks with the same (or 98% similar) guts as the expensive nameplate! Win-win.


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## 000zero (Mar 12, 2011)

I don't think people *always* get better results, I had a Clarion amp in my setup for a couple weeks, while by buddy tested out my XXD, and the Clarion did not sound as good. I think you are making everything out to be very cut and dry, which may be true for the general public, but there are some objective people (especially on a DIY forum) out there who are only interested getting the best sound they can with the resources they have regardless of brand.


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## WLDock (Sep 27, 2005)

ryan s said:


> The thing is, though, people *always *have a better result when they swap equipment...isn't it funny like that?
> 
> Since a good chunk of amp buying is psychoacoutics, I don't spend more than necessary. And Zeff amps are great since they're available in cheaper heatsinks with the same (or 98% similar) guts as the expensive nameplate! Win-win.


 Well, I think I found out a long time ago that I would not spend more than neccessary on amps. *Back in the early 90's I had an Alpine 4 channel amp in my system...I think it was a 3554? I swapped it out with a PPI Art Series A404 and did not hear a difference.*

Ever since then I have desired $1K+ amps but have yet to spend money on them. My next system will have a couple of Zeff amps (Clarions) on the midbass and sub. I would love to add an ARC SE Series for the midrange and tweeters but.......I have a line and good price on a DLS A4 so...maybe that is route I will take? I am a poor and cheap DIYMA busta'!

I guess I still have issues with buying $1K+ amps for car audio. However, a few of us did hear a difference between two amps....and I seriously doubt that using a more scientific approach with level matching etc... would have made a difference. The definition and staging changed!


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## kvndoom (Nov 13, 2009)

000zero said:


> I don't think people *always* get better results, I had a Clarion amp in my setup for a couple weeks, while by buddy tested out my XXD, and the Clarion did not sound as good. I think you are making everything out to be very cut and dry, which may be true for the general public, but there are some objective people (especially on a DIY forum) out there who are only interested getting the best sound they can with the resources they have regardless of brand.


I understand what he's saying though. In your mind you just got something new so you want it to be better than what you had... _especially _if you paid more. (when I say "you" I just mean people in general) I'd say overall the JL Slash amps are the best out of all I've used (and I've had amps that cost more, and ones that cost less), but they don't suit my needs at this point.


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## 000zero (Mar 12, 2011)

kvndoom said:


> I understand what he's saying though. In your mind you just got something new so you want it to be better than what you had... _especially _if you paid more. (when I say "you" I just mean people in general) I'd say overall the JL Slash amps are the best out of all I've used (and I've had amps that cost more, and ones that cost less), but they don't suit my needs at this point.


I understand what he is saying, you explained it better then he did I think. That is how I used to be when I started out before realizing the brand isn't always everything. I was only pointing out that not ALL people are like that.


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## ChrisB (Jul 3, 2008)

000zero said:


> I got the KS300.4 and have had it hooked up for a about a week now and I would say it is definitely a good improvement over the XXD 4080. The rest of my setup stayed the same so it was basically an side by side comparison, I can hear more detail and the music seems a bit more airy (not sure if that is the word I am looking for). My L1V2 are singing nicely now, they are some amazing tweets. I couldn't fit my memphis X-over under the seat anymore so I am just using the crossover on the KS for now so I have some freq overlap between my mid and mid-bass, I think I will improve the clarity in the mid frequencies once I figure out a way to fit the x-over under the seat. I was thinking of maybe getting a piece of 1/4 MDF and raising one side up and placing it so it is slightly overlapping with the KS, there is a lot of vertical space under my seat so I think this could work.


I'm glad you like it.


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## Jsracing (Apr 1, 2011)

You may be hearing a bit less noise with the KS. Yes, much of audio, or any high priced purchase, is mental and subjective, but many of us try to inject some objectiveness to varying degrees of success.
G youlad like the KS more.


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## envisionelec (Dec 14, 2005)

I'm rather concerned that the Class H term of GH is being misrepresented. 

A little background...Class G has been around a long time in professional audio where vanishingly low distortion is of little importance. It's the use of stepped voltages to reduce dissipation between idle to ~1/3 output while keeping the higher rail voltage turned off until they're required. The amplitude of the input signal determines the point at which the upper voltages are turned on. The "steps" are generated from taps on the power transformer. 1:1 might be 25V while 2:1 would be 50V, and so forth. Most G amps have two levels, with some having three.

The H-term means that the power supply is actively involved in the switching. More precisely it is a wide-range, variable output supply. Typical use of a Class H power supply puts the rail voltage ~6-8V over the signal amplitude...also known as a tracking supply. Carver was one of the first to use Class GH with commercial success. On subwoofer amplifiers.

My concern is that the H-term is rather slow by necessity. If it is fast, you must be able to detect changes in amplitude at a rate of 2x (4x is better) the highest frequency or alias distortion occurs. That's 40-44kHz (80-88kHz) for most amps. The problem is that it is difficult to (reliably) design a circuit that will do this across the entire bandwidth, with adequate phase/gain response. There are compromises...

Also, switching rail amplifiers typically have Class B type switching distortion due to the rail stepping at high frequencies. 

I'm intrigued to learn how they're doing it effectively.


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## subwoofery (Nov 9, 2008)

envisionelec said:


> I'm rather concerned that the Class H term of GH is being misrepresented.
> 
> A little background...Class G has been around a long time in professional audio where vanishingly low distortion is of little importance. It's the use of stepped voltages to reduce dissipation between idle to ~1/3 output while keeping the higher rail voltage turned off until they're required. The amplitude of the input signal determines the point at which the upper voltages are turned on. The "steps" are generated from taps on the power transformer. 1:1 might be 25V while 2:1 would be 50V, and so forth. Most G amps have two levels, with some having three.
> 
> ...


That's why I'm planning to use my Genesis DMX on my midbasses  
From my gathering, the DMX (Class G) has been designed to drive difficult loads like a subwoofer. 
Genesis has 2 other Class G amps: 
The DMA which operates in Class A mode then switch to Class G 
and Project P15 tube amp ; same as above A then G. 

Would be good to know what went behind the conception of those amps... 
Wish Gordon would chime in... 

Kelvin


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## WLDock (Sep 27, 2005)

envisionelec said:


> I'm rather concerned that the Class H term of GH is being misrepresented.
> 
> A little background...Class G has been around a long time in professional audio where vanishingly low distortion is of little importance. It's the use of stepped voltages to reduce dissipation between idle to ~1/3 output while keeping the higher rail voltage turned off until they're required. The amplitude of the input signal determines the point at which the upper voltages are turned on. The "steps" are generated from taps on the power transformer. 1:1 might be 25V while 2:1 would be 50V, and so forth. Most G amps have two levels, with some having three.
> 
> ...


Great post, I wondered this as well and wondered why we have not seen more of these type amps years ago. I would guess that it is not as easy as it sounds?

Here is Clarions talk about it from their application guide:

_Hybrid Class GH Power Supplies
Amplifier efficiency has never been more important than it is in today’s modern vehicles. Alternators, batteries, and factory wiring are smaller than ever to produce the lightest and most fuel efficient vehicles possible at the lowest costs. Clarion’s XH7110 amplifier features a Hybrid Class GH power supply. This technology is the result of years of design and testing to offer the optimum balance of sound quality and efficiency - exactly what a Clarion customer demands.

The operation of a Hybrid Class GH amplifier is very simple. Traditional amplifiers use a Class AB output device topology. Essentially, there are a set of switching devices (transistors) for the positive half of the waveform and another set for the negative half of the waveform. These devices operate linearly, passing more current through them as more signal is sent to them. The drawback with Class AB topology is that the output devices operate in their resistive region, rarely fully on or off. This results in a great deal of heat being generated and energy wasted. 

Around a decade ago, the introduction of Class D amplifiers to the car audio market offered a significant improvement in amplifier efficiency at the expense of sound quality and control. Class D amplifiers operate by cycling the output devices fully on and off very quickly. Adjusting the on versus off time effects a change in output level. One of the many drawbacks of Class D amplifiers is that they require large filtering networks after the output stage to clean up the signal and remove high frequency switching noise. Class D amplifiers can cause significant electrical interference that can affect radio reception. Clarion’s Hybrid Class GH technology is truly the best of both worlds. Clarion’s XH7110 amplifier uses a fully analog Class AB audio path. This means tight, controlled, dynamic power output. 

How does Hybrid Class GH work to improve efficiency if the audio path is all analog? This of the new Dodge Hemi or Cadillac Northstar engines. These engines have the ability to shut down a number of cylinders to reduce fuel consumption and heat generation when under light loads. The power supply of a Hybrid Class GH amplifier works in the same way. A micro controller (computer) inside the amplifier controls the output voltage of the power supply. It keeps the voltage just above the output level necessary to reproduce the audio signal. This means that although the output devices are operated linearly, they are almost fully on - it’s the power supply voltage that changes. The result is a significant improvement in efficiency without any effect on the amplifier’s sound quality._


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## dcfis (Sep 9, 2016)

Old thread but had anyone tried the new cadence qrs class g/h amps?


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