Power calculator ( Amp , AVR) - How much power do I need ?

[AVUser001]

I'm looking at the one on the Crown site and I like it a lot more than AF. At least I can fill in the fields and get results. Again tho, I can see it confusing a newbie. A lot of folks that come here have no clue what a reference level is, headroom or speaker sensitivity.

I'd say it's an alternative for the more technically minded. Some folks will get more from it than others. You can usually get a feel for where someone's at within a couple of posts.

Crown Audio - Professional Power Amplifiers | English (US)

www.crownaudio.com

@Pogre , Yes, the Crown one, which I linked earlier as alternate, atleast prompts the user to add the headroom explicitly and is better than homestead , while the homestead relies on user's understanding to add the peak manually into the calculator . For eg, a headroom of 20db translates to a 100 fold power increase .., a big difference in amp/AVR requirement and yet the homestead takes it for granted ,relying on User's understanding of such topics.

The gap with Crown is that , its also based on 8 Ohm.., and doesnt account for speakers with other sensitivities. There's whole bunch of 4Ohm speakers(like MartinLogans and speakers that consistently drop below 4-5 Ohms)...and the homestead one is going to get it plain wrong for those. Becos you need to double the power required for 4 Ohm(vs 8 Ohm).

With homestead , we're actually expecting people to be more knowlegeable about all these , relying on them to factor in speaker impedence, headroom etc and trial & error process manually..

Homestead asks for speaker sensitivity , SPL level , boundary gain too... Its not like it does it auto-magically ;-)

 

[Pogre]

@Pogre , Yes, the Crown one, atleast prompts the user to add the headroom explicitly and is better than homestead , while the homestead relies on user's understanding to add the peak manually into the calculator . For eg, a headroom of 20db translates to a 100 fold power increase .., a big difference in amp/AVR requirement and yet the homestead takes it for granted ,relying on User's understanding of such topics.

The gap with Crown is that , its also based on 8 Ohm.., and doesnt account for speakers with other sensitivities. There's whole bunch of 4Ohm speakers(like MartinLogans and speakers that consistently drop below 4-5 Ohms)...and the homestead one is going to get it plain wrong for those. Becos you need to double the power required for 4 Ohm(vs 8 Ohm).

With homestead , we're actually expecting people to be more knowlegeable about all these , relying on them to factor in speaker impedence, headroom etc and trial & error process manually..

Homestead asks for speaker sensitivity , SPL level , boundary gain too... Its not like it does it auto-magically ;-)

When I link homestead it's almost always to illustrate my point to folks (many who who don't understand the difference between hz and dB), which is that it takes far more power than most realize to see any real gains. It does a fine job of that with very little effort or understanding. A lot of folks think doubling (or even less) your amp power has this huge effect on sound quality.

Like HD mentioned too, a lot of times there'll be a caveat or some sort of small explanation of how to interpret the results as well.

 

[AVUser001]

Agreed, Crown's is a good one. I would say if we link the homestead and the receiving end comes back puzzled/confused by it, then we can link the Crown one and remind them they would likely be on the conservative side if they based their power need on this calculator.

OK , settled than The crown calculator, which I linked earlier..,is atleast a power requirements calculator, for a given SPL ( whereas the homestead is a SPL calculator for a given power - inverse ) and also it accomodates the headroom, which the homestead doesnt. We still need to provide the caveat around speaker impedence, with Crown, when linking so people dont end up with wrong power spec...

Dont think I want to spend any more time on this topic .. Like I said, I wanted to bring up on the forum, on something that was irking me, for sometime .. make sure people understand the pitfalls with the homestead and factor those , when linking/estimating power requirements for amp or AVR.

 

[AVUser001]

When I link homestead it's almost always to illustrate my point to folks (many who who don't understand the difference between hz and dB), which is that it takes far more power than most realize to see any real gains. It does a fine job of that with very little effort or understanding. A lot of folks think doubling (or even less) your amp power has this huge effect on sound quality.

Like HD mentioned too, a lot of times there'll be a caveat or some sort of small explanation of how to interpret the results as well.

and you're doing a fine job at that...

if people are equating more power to better sq - that's a different issue to be dealt with ..,irrespective of the calculator. there's too much misunderstanding/misinterpretation going on , on every topic!

Pls dont mistake me - not at all targeted at you , fine gentlemen ...

 

[AVUser001]

And, just by the way, both "" terms are "iffy" just to be generous. You obviously know that but you seem linear with them (yet not so with the homestead..) With due respect, I do see you point and may even understand why the homestead one "troubles" you but I do urge you to be fair, be more even handed with your criticisms. I am harsh with the misused terms too, but I did highlight the fact that those were "technical" errors that homestead also made.

Not at all..that AF calculator has misleading terms too ..resistance, efficiency etc... not perfect . Its not mine ;-)

 

[PENG]

OK , settled than The crown calculator, which I linked earlier..,is atleast a power requirements calculator, for a given SPL ( whereas the homestead is a SPL calculator for a given power - inverse ) and also it accomodates the headroom, which the homestead doesnt. We still need to provide the caveat around speaker impedence, with Crown, when linking so people dont end up with wrong power spec...

Sure, if someone ask "how much power do I need for my speakers", we can recommend the Crown audio calculator. Conversely, if the question is something like "Should I add an external amp to my AVR? or "Is my amp powerful enough?" kind of questions, then I would still link the homestead version. In both cases, it would be helpful to include the appropriate cautionary note on the impedance and the 2.83 V vs 1 W thing.

 

[AVUser001]

Sure, if someone ask "how much power do I need for my speakers", we can recommend the Crown audio calculator. Conversely, if the question is something like "Should I add an external amp to my AVR? or "Is my amp powerful enough?" kind of questions, then I would still link the homestead version. In both cases, it would be helpful to include the appropriate cautionary note on the impedance and the 2.83 V vs 1 W thing.

Cool , my ask exactly

 

[PENG]

Cool , my ask exactly

Good to know.

Here's the one I did in Excel. I'll try to find some freeware to convert it for web use. Suggestions are welcome, to make it easier to understand/use.

 

[lovinthehd]

Going to make that like an official AH app to refer to? That would be nice if it were without the actual spreadsheet interface....I really don't get along with spreadsheets these days

 

[PENG]

Going to make that like an official AH app to refer to? That would be nice if it were without the actual spreadsheet interface....I really don't get along with spreadsheets these days

Okay for me but I don't have the authority.

 

[lovinthehd]

Okay for me but I don't have the authority.

Now that I can see it (was on phone earlier) down towards the bottom as far as given amp power maybe should have a reminder about at what impedance?

Well AH can only say yes/no....but appreciate the effort!

 

[PENG]

Now that I can see it (was on phone earlier) down towards the bottom as far as given amp power maybe should have a reminder about at what impedance?

Well AH can only say yes/no....but appreciate the effort!

Thanks, impedance (the first input field) is there for user input already. The calculated amp power will change according to the impedance value input by the user. But I think you are referring to the given power part for calculating SPL.

I meant to include a note on the color code, that is, yellow for input and green the calculated values. Edited now, thanks again for the feedback.

 

[lovinthehd]

Thanks, impedance (the first input field) is there for user input already. The calculated amp power will change according to the impedance value input by the user. But I think you are referring to the given power part for calculating SPL.

I meant to include a note on the color code, that is, yellow for input and green the calculated values. Edited now, thanks again for the feedback.

Yeah I know a bit redundant but we're talking guys and watts and stuff! Considering many still only think of the nominal 8 ohm amp rating.....

 

[PENG]

Yeah I know a bit redundant but we're talking guys and watts and stuff! Considering many still only think of the nominal 8 ohm amp rating.....

I know I can count on you sharp mind/eyes. Please let me know any time if you see any thing else that may be potentially misleading/confusing. I just edited it again using a different impedance and distance input (6 ohms and 3 meters). I originally made it for calculating power required only, but after reading AVUser's comments, I decided to modify it slightly so it is now a dual purpose one that can be used as a spl calculator like the homestead one. I hope that does not make it inherently confusing.

 

[PENG]

I thought I would check my calculator by entering the appropriate values to make it self checking.
So I picked the following input data:

Impedance..................8 Ohms (so that I an check it with the homestead peak spl calculator.
Distance......................3 meter, in the https://myhometheater.homestead.com/splcalculator.html, enter 9.84 ft.
Sensitvity.....................88 dB/2.83 V/1m, same for the other calculator because impedance is 8 ohms.
Target peak SPL.........105 dB (THX Reference)

So the calculator power required as shown in the screenshot is 451.57 W

Then I entered this same value into the second part of the calculator, that is, input it to the "Given amplifier output power (W)" field, and sure enough the calculated SPL is exactly 105 dB, so self checking checks out. Also checks out with the homestead.com calculator.

 

[Verdinut]

Good to know.

Here's the one I did in Excel. I'll try to find some freeware to convert it for web use. Suggestions are welcome, to make it easier to understand/use.

View attachment 35395

Wasn't sensitivity to be specified at 2.83v/1 meter rather than at 1 watt?

 

[PENG]

Wasn't sensitivity to be described at 2.83v/1 meter rather than at 1 watt?

I think we all prefer 2.83 V/1 meter, but many manufacturers are still using the 1 W/1 meter. I cited a few examples a couple pages back I think. Monitor Audio being one of those.

It doesn't matter with my calculator as you have the choice to use either. Not just speaker manufacturers, the myhometheater.homestead calculator as well as the Crown Audio calculator are based on the 1W/1m sensitivity spec too.

 

[AVUser001]

Good to know.

Here's the one I did in Excel. I'll try to find some freeware to convert it for web use. Suggestions are welcome, to make it easier to understand/use.

View attachment 35395

Cool. So its essentially similar to AcousticFrontiers, fixing the terminologies we discussed earlier on this thread and making it more explicit .

I'm good - what I have been going back & forth with you guys for the past couple of days ;-) , as whats needed to product an accurate estimate of power requirement.

Looks like you're actually asking users to input Room gain in dB and Gain from multiple speakers in dB...rather than Yes/No for Room gain or #speakers and defaulting to certain gain(dB) as in AF & homestead .

Wont that make people scratch their heads ;-) I mean , the guys earlier(pogre, ryanasour) were arguing about incredible complexity and confusion with even asking the user basic inputs like speaker impedence and additional headroom (which are absolutely essential) !!

I'dnt be asking those gains in dB to end-users, but rather derive them , from more simpler questions ( #Speakers, Speakers placement) like what other online calculators do.

Also seems you're mixing both the peak SPL and Amp Power requirement into same - not sure about that , might confuse people,I think. I'd keep them separate, if possible.

Other than that, I'm good.. Now, if gene can agree to you hosting this calculator at AH - that'd be ideal !

 

[AVUser001]

I originally made it for calculating power required only, but after reading AVUser's comments, I decided to modify it slightly so it is now a dual purpose one that can be used as a spl calculator like the homestead one. I hope that does not make it inherently confusing.

Pls see my other comment..., Think it might make it simpler, keeping the peak SPL and amp power separate , to reduce confusion .

 

[AVUser001]

I thought I would check my calculator by entering the appropriate values to make it self checking.
So I picked the following input data:

Impedance..................8 Ohms (so that I an check it with the homestead peak spl calculator.
Distance......................3 meter, in the https://myhometheater.homestead.com/splcalculator.html, enter 9.84 ft.
Sensitvity.....................88 dB/2.83 V/1m, same for the other calculator because impedance is 8 ohms.
Target peak SPL.........105 dB (THX Reference)

So the calculator power required as shown in the screenshot is 451.57 W

Then I entered this same value into the second part of the calculator, that is, input it to the "Given amplifier output power (W)" field, and sure enough the calculated SPL is exactly 105 dB, so self checking checks out. Also checks out with the homestead.com calculator.

View attachment 35398


View attachment 35397

Cool...Trust-but-verify ;-), the power requirement calculations are standardized and I did cross-verify , Homestead, Crown and Acoustic Frontiers - they all matched , for common inputs. I wouldnt expect any less from you ;-)