Taking the load off the RX-A3040 - Small Class D 4-channel Amp for Height Speakers Recommendation

[Fried Chicken]

In my current 7.2.4 setup, the poor rx-a3040 has to handle 9-channels of power amplification (the front speakers are driven by a separate Yamaha M65 power amp). Even with the crossovers set to higher frequencies, there's still that 8Ω impedance being split up.
I'm thinking of adding some small efficient inexpensive class-D amp for the height speakers so the RX-A3040 "only" has to drive 5 channels.

I've only briefly looked, but Fosi caught my eye. I'm wondering if there are other/better new/used offerings. I want to stick with Class D b/c I put low priority on height channels, and I don't want to add to room heating.

Thanks!

 

[TLS Guy]

In my current 7.2.4 setup, the poor rx-a3040 has to handle 9-channels of power amplification (the front speakers are driven by a separate Yamaha M65 power amp). Even with the crossovers set to higher frequencies, there's still that 8Ω impedance being split up.
I'm thinking of adding some small efficient inexpensive class-D amp for the height speakers so the RX-A3040 "only" has to drive 5 channels.

I've only briefly looked, but Fosi caught my eye. I'm wondering if there are other/better new/used offerings. I want to stick with Class D b/c I put low priority on height channels, and I don't want to add to room heating.

Thanks!

Very little power goes to ceiling speakers, and that will not significantly offload your AVR. If you want to do that, then you need to power the front three. What you are preposing is a waste of money.

 

[Fried Chicken]

Very little power goes to ceiling speakers, and that will not significantly offload your AVR. If you want to do that, then you need to power the front three. What you are preposing is a waste of money.

I mean... do you have something to quantify that?

If you look at the specs of the Anthem MRX1120, they're basically doing exactly what I'm suggesting:

140 watts per channel into 8 ohms (20-20,000 Hz) at 1% THD with 2 channels driven

• Class AB amplification for channels 1-5, 140 watts with 2 channels driven
• Class D amplification for channels 6-11, 60 watts per channel with 2 channels driven

 

[TLS Guy]

I mean... do you have something to quantify that?

If you look at the specs of the Anthem MRX1120, they're basically doing exactly what I'm suggesting:

It is not the power of the amps you buy for those speakers, but the power they deliver to the speakers they are connected to. Most of the power is going to go to the left right and center front speakers, and the power they draw dwarfs the rest. So if you want to offload your AVR in any significant way, it is providing alternative power to the front three speakers.

 

[Fried Chicken]

Very well.

What inexpensive 2, 4 or other multi-channel class-D amplifiers are available?

 

[TLS Guy]

Very well.

What inexpensive 2, 4 or other multi-channel class-D amplifiers are available?

No idea. However you probably don't want to power any of your front speakers with a cheap amp. I avoid junk. Often inexpensive means trouble which means expensive in the long run. I choose carefully and go for quality and that has been very economic for me over the long run. I hate trouble and do my best to avoid it.

 

[BoredSysAdmin]

Very well.

What inexpensive 2, 4 or other multi-channel class-D amplifiers are available?

Here's an (relatively) inexpensive 3-channel class-D amp which even TLS Guy can't objectively critique.

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

Also available as a 2-channel or monoblock.

Also, VTV uses Purifi design in their amps, and they measure excellently as well.

VTV Purifi | VTV Amplifier

He's right on the point - if you want to offload your AVR, focus on LCR speakers as they use the bulk of the sound/power.

 

[Fried Chicken]

No idea. However you probably don't want to power any of your front speakers with a cheap amp. I avoid junk. Often inexpensive means trouble which means expensive in the long run. I choose carefully and go for quality and that has been very economic for me over the long run. I hate trouble and do my best to avoid it.

(the front speakers are driven by a separate Yamaha M65 power amp)

Here's an (relatively) inexpensive 3-channel class-D amp which even TLS Guy can't objectively critique.

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

Also available as a 2-channel or monoblock.

Also, VTV uses Purifi design in their amps, and they measure excellently as well.

VTV Purifi | VTV Amplifier

He's right on the point - if you want to offload your AVR, focus on LCR speakers as they use the bulk of the sound/power.

I'm thinking more along the lines of the Fosi V3... used on eBay. I don't care about the height channels much at all. Something that can make rain sounds and not interfere with the receiver's sound mixing would fit the bill.

 

[TLS Guy]

I'm thinking more along the lines of the Fosi V3... used on eBay. I don't care about the height channels much at all. Something that can make rain sounds and not interfere with the receiver's sound mixing would fit the bill.

In that case just leave your AVR as is. No point in adding pieces of lower quality than what you have. You can upgrade, but downgrading is a bad idea.

 

[Fried Chicken]

I just want recommendations for a cheap class D amplifier. From what I see about the Fosi v3; sourcing a low noise power supply seems to be the problem.

Perhaps someone here has a recommendation for one or the other, or can confirm the Fosi v3 is a good option.

 

[PENG]

I just want recommendations for a cheap class D amplifier. From what I see about the Fosi v3; sourcing a low noise power supply seems to be the problem.

Perhaps someone here has a recommendation for one or the other, or can confirm the Fosi v3 is a good option.

I have 3 of those, just sold one, the V3 is capable of transparent sound quality. I would however, recommend the 3e A7, that runs cooler and have gain settings, plus balanced connections.

3e audio A7/A7 Mono Amplifier Review | Audio Science Review (ASR) Forum

I have two of those, monoblock version that replaced my Bryston 4B SST, Parasound Halo A21, and the buckeyeamp Hypex 502MP.

No Yamaha power amp or integrated amp could come close to such class D chip based amps on the test bench in the <$2,000 range (or higher).

 

[PENG]

For those who don't care much about where those chip amps are made, the likes of the Fosi V3, 3 e Audio, and a few other similar amps could be great options for pairing with midrange AVRs for the LCR or the surround/height channels, based on specs and price. Note that there are hardly any popular hifi brand power amps show up in the chart below, other than a few by NAD. Also note that the fantastic $3,499, 100 WX2 class AB Benchmark AHB2 is no longer the SINAD king. Yes SINAD is just one metric but you can dig in and see how well they measured on other important metrics.

3e audio A7/A7 Mono Amplifier Review | Audio Science Review (ASR) Forum

 

[Fried Chicken]

I have 3 of those, just sold one, the V3 is capable of transparent sound quality. I would however, recommend the 3e A7, that runs cooler and have gain settings, plus balanced connections.

3e audio A7/A7 Mono Amplifier Review | Audio Science Review (ASR) Forum

I have two of those, monoblock version that replaced my Bryston 4B SST, Parasound Halo A21, and the buckeyeamp Hypex 502MP.

No Yamaha power amp or integrated amp could come close to such class D chip based amps on the test bench in the <$2,000 range (or higher).

Why not the Topping B100 that tested top in the test you linked and is $300?

Even still, I'm thinking even cheaper, like the Fosi v3 lol

 

[PENG]

Why not the Topping B100 that tested top in the test you linked and is $300?

Even still, I'm thinking even cheaper, like the Fosi v3 lol

I prefer class d amps in general.

 

[AcuDefTechGuy]

In my current 7.2.4 setup, the poor rx-a3040 has to handle 9-channels of power amplification (the front speakers are driven by a separate Yamaha M65 power amp).

None of these AVR's will be subjected tol ALL CHANNELS DRIVEN in real life.

As TLS and others may have said, the surround channels will require very little power.

So if you just WANT to add a power amp like many enthusiasts do for the sake of owning an amp, then get a power amp that you can be PROUD of for pride of ownership, not some cheapass amps.

Otherwise, I agree with TLS - just stick with the Yamaha.

 

[Alex2507]

I agree with TLS

Strange days, indeed. I just want to make sure you're okay. You didn't get concussed in a car accident or something, did you? Should we send help? A wellness check?

 

[Fried Chicken]

None of these AVR's will be subjected tol ALL CHANNELS DRIVEN in real life.

As TLS and others may have said, the surround channels will require very little power.

So if you just WANT to add a power amp like many enthusiasts do for the sake of owning an amp, then get a power amp that you can be PROUD of for pride of ownership, not some cheapass amps.

Otherwise, I agree with TLS - just stick with the Yamaha.

Idk; I'm not convinced. I want numbers. I also want a technical understanding of how an amplifier can discriminate between channels. It could perhaps also remove crosstalk from the height channels: driving only the center and the surrounds.

I poked inside the receiever, but what I saw horrified me so I put the lid back on. There are two amplifier boards, one left one right. I think the one on the right has 10 output transistors, the one on the left only 8.

 

[3db]

In my current 7.2.4 setup, the poor rx-a3040 has to handle 9-channels of power amplification (the front speakers are driven by a separate Yamaha M65 power amp). Even with the crossovers set to higher frequencies, there's still that 8Ω impedance being split up.
I'm thinking of adding some small efficient inexpensive class-D amp for the height speakers so the RX-A3040 "only" has to drive 5 channels.

I've only briefly looked, but Fosi caught my eye. I'm wondering if there are other/better new/used offerings. I want to stick with Class D b/c I put low priority on height channels, and I don't want to add to room heating.

Thanks!

Why do you think your AVR needs additional power? How big is your room? How far do you away sit from your speakers? How loud do you play your media? What signs do you see that your AVR is running out of power? What make and model of speakers are you using?

 

[TLS Guy]

Idk; I'm not convinced. I want numbers. I also want a technical understanding of how an amplifier can discriminate between channels. It could perhaps also remove crosstalk from the height channels: driving only the center and the surrounds.

I poked inside the receiever, but what I saw horrified me so I put the lid back on. There are two amplifier boards, one left one right. I think the one on the right has 10 output transistors, the one on the left only 8.

The amplifier does not, the input signal does and that goes back to the sound engineer's mix desk. An amp will put out the dynamic of the signal fed to it. So the average volume on the surround channels is way lower than the front three over time. Now a fall of just 3 db. halves the power requirement to any channel. The power to the surrounds is of the order of at least 20db. lower than the fronts over time. So the power provided by the surround amps is miniscule compared to the fronts.

So reducing the load on an AVR requires providing amps for the front three channels.

 

[Golfx]

I just want recommendations for a cheap class D amplifier. From what I see about the Fosi v3; sourcing a low noise power supply seems to be the problem.

Perhaps someone here has a recommendation for one or the other, or can confirm the Fosi v3 is a good option.

You seem to have you heart set on a used fosi v3. So why ask here for advice?

Fosi Audio V3 Amplifier Review

This is a review and detailed measurements of the Fosi Audio V3 stereo amplifier. It was sent to me by the company and costs US $89.99 with stock 32 volt supply. Price goes up to $109.99 with the 48 volt supply. There is a $10 discount coupon right now. Despite its budget price, the V3...

www.audiosciencereview.com

This review by ASR recommended it as well. BTW it is NOT very powerful. It may not help you audibly at all.