Most powerful 5.1 under 5k?

[davewantsmoore]

Make up your mind Dave, the OP's head must be spinning from reading your comments in isolation

 

I read all my comments.   What's to be confused about ?!?

 

 

 only then, the posts come rolling in

 

Post #24 was attempting to nip that in the bud.    "Excessive power" ... and "depends on the speaker"

 

 

That's not helpful.

 

I disagree.   Objectively discussing the choices both past and future is helpful to the OP, and also everyone else reading along.

 

 

And yet on 25 June, when he wrote in response to your question, that he is buying amp before speakers, you didn't 'call out' anything. 

 

I tried to in post #30  (and previous in post #24)   ....   Did I do a very good job.  No.   I'm usually much more blunt and ranty than that   ;-)

 

 

And 4 days before that, you had suggested the Marantz MM8003.

 

Sure.... again I don't understand the confusion.

 

The discussion was tracking specifically around 5.1 receivers ... and using them as preamps ... and I suggested a multichannel power amp.

[Paul Spencer]

I'm flabbergasted that you're gobsmacked.

 

I'm glad to hear it, because there's room for only a certain number of gobsmackers in this forum.

 

I'm absolutely gobsmacked by posts #38 and #39.

 

Do keep in mind that I speak as an Emotiva owner - I speak from actual experience with their products. I think it is useful for the OP to hear from other Emotiva owners.

 

I provided a demo for one of my clients, using some Emotiva products. The intent was to facilitate a sale and said client intended to then go with a custom design. The potential buyer was seriously interested, and almost ready to buy sight unseen. He went away disappointed. My client originally auditioned his speakers with electronics that made them sound much more appealing.

 

My point is not to diss the choice after a purchase has been made, but to point out that now he needs to make a wise choice with the speakers.

[damifly]

Basic point is "pre-amplifier leading sound style, power-amplifier just give power". That was why so many different brands of amplifier. You only need a powerful amplifier when your speaker is very hard to drive. Such as ATC s-20, s-100, B&W 800 series, SPENDOR S-100, 5000$ just go for Emotiva. And you even not mention which speaker you want to drive. All I can say is just HOHO.

[Gee Emm]

The comparison was in relation to the Emotiva blowing up speakers with its power. If the MF750K doesn't blow 'em up, that is a perfect example of why the Emotiva might also not do it.

 

No, it is not a perfect example. It is a poor example.

 

Those different amps deliver power differently, especially when driven harder.

 

Anyway, It's all a bit moot as the OP has the amp he has.

 

Graham

[davewantsmoore]

If the MF750K doesn't blow 'em up, that is a perfect example of why the Emotiva might also not do it.

 

Well obviously it depends on how you use it (either of them).   The devil is in the detail yet again.

 

 

2V output (typical source) direct to the MF750K ... will send 736watts to a 4ohm tweeter.  A rookie-mis-adventurer might easily end up with broken ears and shards of tweeter embedded in their eye.

 

 

 

Or. perhaps you turn the volume down on the source.... to get a more pleasant (still loud) level.

 

95dB peaks (20dB crest) at 4m with 90dB/6R speakers ... requires 0.5 watts ...  which is input V = 60mV  (MF750K is 2.5V sensitive with 29dB gain).   This reduces the SNR of the amplifier by nearly 2000x.   The amp has more like 88dB SNR now (rather than 120 quoted).......    The preceding device is also now outputting 60mV, which is no doubt going to increase it's SNR and relative distortion.

 

The numbers for the Emotiva amp are orders of magnitude worse, as we should reasonably expect  (It has 1.8v input with double the gain and 10dB less SNR)

 

 

Heaps more power than you need is often a disaster.   Often a more powerful amplifier is also more suited to driving difficult speaker loads .... but this is a completely separate problem to "power" which is dictated by the speaker in question, and how loud you want to play it.

[Gee Emm]

Thanks Dave for your succinct explanation.

[Newman]

Dave, you often remind us that 400W of amp only delivers 10 dB more SPL than a 40W amp..... so now you want to argue that amps fall apart 'disastrously' within a 10 dB range when you turn them down? For most amps the THD+N plot increases at very low power levels due to noise, with distortion below the noise. So the main issue is noise, and if we plug in our 400W amp and take a seat and can't hear the noise....

 

The case for using a 500W amp in a normal listening room with 85 dB/W speakers is valid, based on headroom needs and musical dynamics. We might run into issues with a 500W amp on 105 dB/W compression drivers on horns -- that is a total mismatch -- but for someone to buy a 400W amp with the plan to keep it for years, maybe using it with a 'normal' range of speakers over time, that is a plan I have no beef with.

 

Maybe I am just too relaxed about this....

[davewantsmoore]

Thanks Dave for your succinct explanation.

 

LOL.... c'mon, I tried.

[davewantsmoore]

Dave, you often remind us that 400W of amp only delivers 10 dB more SPL than a 40W amp..... so now you want to argue that amps fall apart 'disastrously' within a 10 dB range when you turn them down? For most amps the THD+N plot increases at very low power levels due to noise, with distortion below the noise. So the main issue is noise, and if we plug in our 400W amp and take a seat and can't hear the noise....

 

The case for using a 500W amp in a normal listening room with 85 dB/W speakers is valid, based on headroom needs and musical dynamics. We might run into issues with a 500W amp on 105 dB/W compression drivers on horns -- that is a total mismatch -- but for someone to buy a 400W amp with the plan to keep it for years, maybe using it with a 'normal' range of speakers over time, that is a plan I have no beef with.

 

Maybe I am just too relaxed about this....

 

 

Sure, I have no problem with this.

 

The noise issue .... if you are feeding your amplifier 0.06 volts ... when it's circuit can take 2.5v... then you are going much closer to the noise of the amp....   You are also going (one would assume it has a typical 2v output) much close to the noise of the previous device.

 

... and you also have distortion at low power (below the noise floor).   From the scant work which has been done in that area, it seems like a very underestimated issue.

 

We might run into issues with a 500W amp on 105 dB/W compression drivers on horns -- that is a total mismatch

 

Might.    Yeah that is a fierce understatement there.   

 

Using the numbers from my previous post (admittedly for the MF750K)  .... full output (@4m) of 120dB .... and a power requirement of 0.00008 watts  (80 microwatts!?) for the "average levels" example ....   Your 120dB (impressive!)  SNR has now dropped to 48dB.    ie.  14 million times worse.

 

 

Dave, you often remind us that

 

It only sounds wrong when you drag the context or generalise  ;-)

 

 

The case for using a 500W amp in a normal listening room with 85 dB/W speakers is valid

 

Yes, it is... if the speaker can actually make acceptable sound at 100dB  (un?!likely for home audio?!)

 

... my only laboured point is that this power comes at a price which is often high fidelity.   It all depends on what you want or need.... which takes us full circle to the point that discussing amps without their loads is mostly nonsensical.

 

 

The real trick is that if you want high quality output at large levels, you will need high sensitivity .... and if you do this at home you will not need much power....   and if you want to do it with high quality, you will want an amp which does not have excessive power, otherwise you'll be needing to send it a signal which is too low.... and your amp, and the devices before it, will be (generally) delivering much less performance that they're capable of.

Edited August 28, 2013 by davewantsmoore

[Newman]

Yes, it is... if the speaker can actually make acceptable sound at 100dB  (un?!likely for home audio?!)

 

What!!! Are we stuck on the KEF LS50's again?  

 

Take another look at that JBL 590 and tell me it cannot sound good at 100 dB.

[Gee Emm]

What!!! Are we stuck on the KEF LS50's again?  

 

Take another look at that JBL 590 and tell me it cannot sound good at 100 dB.

 

I'm calling it. I think Newman is a Trol, with a capital T.

 

When he runs out of answers on amplifiers, he changes the subject to speakers.

 

Why didn't I see it before!?

 

Graham

[davewantsmoore]

What!!! Are we stuck on the KEF LS50's again?  

 

They are a prime example.   They have poor distortion numbers at 90dB/1m .... 100dB (or 106!!!) at the listening position is very large jump.   It can't be good.

 

The purpose of 500w here is murky at best.

 

 

Take another look at that JBL 590 and tell me it cannot sound good at 100 dB.

 

It will do 100dB@1m on barely 5 watts ... At 4m this would be starting to approach the recommended amp power of 250 watts.

 

So you could perhaps infer from that "only just"...   but it's going to be all sorts of better.    Kinda like bringing a gun to a knife fight... where something with genuinely high sensitivity (approaching 100dB or higher) .... is like taking a tank to a karate tournament.

 

This all quickly comes backs to listening levels/distances....   These are massively loud levels.   X, Y and Z amplifier powers get thrown around all the time as being good or not .... but you can see from the numbers here, that speaker sensitivity and distance has an enormous effect.

 

So the questions before amplifiers, is always just how big IS your room, where and how will you listen, and how much power does your speaker need.   A sensitive speaker which needs 10 watts... changes to 1000 watts for a not sensitive speaker... for the same output.   So 200w (or whatever) is a fierce generalisation.

 

 

It's kinda like saying that a standard-sized claw hammer is a "good choice"  .... but not for building a model aeroplane, or demolishing a house.

 

 

 

 

When he runs out of answers on amplifiers, he changes the subject to speakers.

 

Nope, not troll.     Speakers are where this thread should have headed from the first few posts unfortunately.   They are inextricably linked with amplifiers.    Speaking about amplifiers without speaker specifics is borderline nonsense.

[Gee Emm]

Nope, not troll.

 

I'm reserving my judgement on this.

 

Another great post BtW Dave.

 

Graham

[alistairm]

Gents... page 1 of this thread is a lovely, enthustiastic thread helping the OP choose an amp. (Good choice by the way, I have had Emotiva gear in the past and consider it some of the best value for money around in this hobby!) 

 

Let's all stop quoting each other and squabbling. I've put everyone's toys back in the cot and ask you all politely not to throw them out again. 

 

Al