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Yamaha A6A with Kef Meta setup, Need help on choosing a power amp.

Meridius

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Hi all

i bought a Yamaha a6a about 6 weeks ago as I upgraded and also decided to buy some KEF Meta’s which consists of the R5,R3 and R2c. I have yet to test to see if the amp is capable but have been told it should be fine. I also have a BK Monolith sub and I asked a question if the Yamaha amp struggles what power amp would I need. The YAMAHA states on the book that it can handle 8 to 4ohms front left and right and the centre and rears and atmos are 8 to 6 ohms. The KEF speakers can drop as low as 3.2ohms. The Yamaha might be ok but just wanted to cover all bases just in case In The future I might need to go the power amp route and use the pre outs.

I was advised to stay away from half bridge amps and to go for full bridge amps to stop any sort of supply pumping, still looking to see what this means but I have read that full bridge uses both sides as a power where’s half only give one side power. And also been reading about class d amps and what filters mean which basically means how they stop interference going to not the speakers because how they work. I think I got that right.

So can anyone help me out or suggest or even explain as this is my first time looking into how these work. I have looked these up


The thing is how can you tell if the these are full or half bridge. As the link below has 1 to 5 channels But looked thinner versions of the rt400a 6to12 channel but not sure if it’s full or half bridge.


Thanks for any help or explanations. I really do thank you all who help. New to separates.


 

jonfitch

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The A6A has plenty of power. As long as you cross over the speakers with subwoofer(s) the amp will have enough power to blow your eardrums with those speakers.
 
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Meridius

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Cheers. Just thought I might needed some extra drive as not sure if the speakers would be hard to drive.
 

GXAlan

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It depends how big your room is and how loud you are listening. All of the “warnings” are generally related to my understanding of power consumption requirements. The Yamaha has very aggressive current limiting where all channels driven, it drops to as little as 50W even though it can burst pretty high.

This works OK. My MX-A5000 is 11 x 150W in a relatively small enclosure. For two channels, it can burst to as high as 400W into 4 ohms, but with 7 channels into 8, it already drops to 85 watts.


My bias is that 8 ohm setting on a Yamaha can handle 3.2 ohms fine since the old THX spec was 28V into 3.2 ohms and the RX-Z9/RX-Z11 were THX spec and most of the reason for the switch is thermal management in hot environments


That said IF you run into the protect mode with you A6A, you should consider an external amp. The tricky part is that the A6A generally does a good job at lower pre-out voltages which means you want a high gain external amplifier.
 

poopy

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Cheers. Just thought I might needed some extra drive as not sure if the speakers would be hard to drive.

How many channels are you going to drive?
You have the possibility to bi-amp your front left and front right.
 
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Meridius

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@poopy. I have a 5.1 system and looking into the future of adding 4 atmos speakers. My room is about 4.5m square and normally listen at volumes -35db to -15db.

@GXAlan what power amp would you suggest out of interest as many have suggested a full bridge Apollon.
 

GXAlan

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@poopy. I have a 5.1 system and looking into the future of adding 4 atmos speakers. My room is about 4.5m square and normally listen at volumes -35db to -15db.

@GXAlan what power amp would you suggest out of interest as many have suggested a full bridge Apollon.

I think you will be fine with the A6A’s internal amps with that listening volume and size. Atmos speakers shouldn’t stress your setup much).

That said, the Apollon is great because it has user selectable gain.

If you assume that 2V is what you get at 0 dB. At -15 dB, you are at 0.356 V.

For a 29 dB amplifier, 0.356V pre out means 10V at the amplifier. 10*10/4 = 25 watts into 4 ohms.

But remember, -15 means peaks at -15 and -35 dB is the average. So you should have plenty of power using this back of the napkin calculation.

25 watts for a R5 meta at 87 dB at 15 feet with some room gain gets you to 90 dB at the listening position which also makes sense for your -15 dB estimate.
 
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Meridius

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Cheers, . It’s all very complicated as I don’t really understand the maths you just gave me but I think, you mean if the amp outputs 2v at ref levels 0db so lowering the volume to,-15db which is still very loud your dividing the 2v power down to 0.356v @ -15db. And your using 29 dB Gain as that’s the highest the Apollon amp setting is And where’s the 10v part coming from or do you mean the 10v is 0db ref level from the external amp meaning 8v more power than the Yamaha amp at the same volume level.

So 10vx10v =100 divide that into 4ohms which is 25wats. But why 10 x 10v

So how do you know the 0db is 2v on a Yamaha a6a pre outs . Edit read this on another forum
"I just mentioned the RCA out rated output is 2Vrms, as stated in the Yamaha manual though they can go up to 4Vrms without distortion"

So what your saying the ya, can drive 4ohms at 25w but the Apollon can drive them at 700w so way more. ?

The kefs are rated at 125w for the r5 I think. So the Yamaha could never drive them Fully unless a power amp is used but these sound way more over powered

so what would you go for if you had to choose the amp.
 
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GXAlan

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You don’t know until you actually measure with a multimeter what the load is but the math is a reasonable initial estimate. The 10V comes from

0.356V + 29 dB = new voltage, which happens to nicely round to 10V
——
The A8A was measured by one of the readers here and it definitely starts to lose SINAD at higher voltages. It all depends what people call distortion. 1%? 0.1%? 0.1% is still 60 dB SINAD.
——
I personally would just run your A6A.

The A6A in 5.1.4 is likely to be a better experience than A6A In 5.1.0 with the external amp when faced with the budget that you face.

But the Apollon is a good choice if you really want an amplifier.
 

ijhammo

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You don’t know until you actually measure with a multimeter what the load is but the math is a reasonable initial estimate. The 10V comes from

0.356V + 29 dB = new voltage, which happens to nicely round to 10V
——
The A8A was measured by one of the readers here and it definitely starts to lose SINAD at higher voltages. It all depends what people call distortion. 1%? 0.1%? 0.1% is still 60 dB SINAD.
——
I personally would just run your A6A.

The A6A in 5.1.4 is likely to be a better experience than A6A In 5.1.0 with the external amp when faced with the budget that you face.

But the Apollon is a good choice if you really want an amplifier.
Useful insight - thanks GXAlan.

I have the A6A also and want to run a full 7.2.4 setup. I have recently upgraded my speakers to all Dynaudio (Evoke 20s, 25C, 10s, P4-W65, & P4-C65) so everything is timbre matched (plus I just love the Dynaudio sound). I have as similar room size to Meridius and am running an Arendal 1723 1S sub (possibly 2 in a few months)

I have to offload at least 2 channels and debating whether I offload the rear Atmos to something like a IOTAVW PA3 (cheap option) or go for a higher end for LCR?

Thoughts?
 
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