500 watts enough for Ultimax 18"?

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DIYhopeful

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Joined 2019
#1
Hi,

I'm not a crazy bass head guy. Just need some low end fill and support for my main speakers. I very rarely listen above 90 dB on my main speakers for either movies or music. Debating between a sealed sub or a full marty. Sealed requires more power right? Might go full marty to get better output. Correct me if I'm misinformed.

I'm leaning heavily towards the Dayton SPA500DSP plate amp instead of the SPA1000 because it only weighs 1 or 2 KGs instead of 10 KGs and is priced quite a bit lower. Or if you suggest some other alternative amplifier which you believe is better suited.
 
#2
Your driver has about 86 dB/2V sensitivity (2 pi, e.g. standing on the floor).
So at your normal listening levels of 90 dB you will need around 40 watts maximum for music with 12 dB crest factor. Some more for enjoying movies.

86 dB @ 1W
89 dB @ 2,73 V = 2 W at 4 ohms
96 dB @ 10 W
102 dB @ 40 W
112 dB @ 400 W
115 dB @ 800 W

(Not considering thermal compression and varying impedance, for simplicity)

So you have plenty of headroom for equalization, if you build a closed box, even with the 500 W amp.

Difference between 500 and 1000 W is only 3dB, so just noticeable.
 
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#3
Hi, thank you for your reply. I just looked up some used amplifiers in my area and someone nearby is selling a mint condition Crown XLS 1502 for $200. Should I go with that since it's much cheaper than the plate amplifiers, my only concern is the input sensitivity. I believe my AVR has a 1.0V/1.2kohm pre out and the Crown accepts either 0.775V or 1.4V. This option is looking much better to me. Save quite a few bucks.
 
#6
that’ll work. Plus I love the convenience of having those played amps with the Bluetooth for the signal that way you can move them wherever you need to and all you have to worry about is the power cord. I think some of the Bluetooth stuff has gotten rid of the majority of latency as well not sure I haven’t really paid attention lately?

I have a coule of the SA1000 but also the DSP 800. It works fine too unfortunately it’s a waste of 200 W that they dedicated to the top and too high to use it for anything but a horn loaded top in PA or something… there’s a permanent crossover setpoint at like 1000 I think? Still works great for the RS 265On it and I imagine the SA 500 will be just fine result max I have it on essay 1000 and I don’t ever turn it up to where I’m ever going to notice twice the wattage is missing. the inverse square law works just the same inside my brain I think as it does in the foundation or the oak cabinetry, They’re both still going nuts no matter what those levels.

Youre still gonna **** off the neighbor if you wanted to push your luck in a normal residential area with decent size yards.

but while you’re at it those things sure are a monster if given a vented cabinet. And if you’re gonna give up the amp why not get a little back? After all it’s supposed to be fun but it can still be cheap if you work The angles and angles in the math. It’s all the same conservation of dollar bills equals the conservation of energy in another form.

take the power back, save the wallet fOr something else. You’re not missing out on anything that way.
 
#7
Everyone is forgetting room gain, where the sub will sit. Middle of the room? Corner of wall and floor? Corner of two walls and floor?
I second the suggestion to build a closed box. Blends in the room far easier with less cut needed. Sounds cleaner, no port chuffing etc.
 
#8
tvrgeek said:
Everyone is forgetting room gain, where the sub will sit. Middle of the room? Corner of wall and floor? Corner of two walls and floor?
I second the suggestion to build a closed box. Blends in the room far easier with less cut needed. Sounds cleaner, no port chuffing etc.
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Nope that’s wrong, you’re cheating go to the principals office!! 😂👍🏻 Not fair, take your ball and go home you’re not allowed to play in this group. You’re playing checkers why not play chess?

Oh yeah chess is harder never mind I don’t feel like it either
 
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#12
DIYhopeful said:
Hi,

I'm not a crazy bass head guy. Just need some low end fill and support for my main speakers. I very rarely listen above 90 dB on my main speakers for either movies or music. Debating between a sealed sub or a full marty. Sealed requires more power right? Might go full marty to get better output. Correct me if I'm misinformed.

I'm leaning heavily towards the Dayton SPA500DSP plate amp instead of the SPA1000 because it only weighs 1 or 2 KGs instead of 10 KGs and is priced quite a bit lower. Or if you suggest some other alternative amplifier which you believe is better suited.
Click to expand...
It would be good to have a little more info. What kind of frequency extension are you looking for? How large is your room (this influences room gain, that has been covered in other responses) AND the big one: how large of an enclosure do you wish or need to limit yourself to? That last one, combined with how much low frequency output you want has a lot to do with required input power and driver displacement demands/requirements. This is because the smaller the box, the less efficient the driver will be at the lowest frequencies, and this is especially true for the UM18 because of the relatively high Qts. For example in a very small box you might need well over 1kW but the same driver in a larger box with 500W will reach the same output level. Keep in mind that your branch circuit can only deliver so much power to your audio system... A large box will allow you to use less amplifier power. Also, many amplifiers (not sure about the Crown you mentioned) cannot meet their specs at 20Hz compared to 1kHz power because the PS is not up to the task. So take the power rating with a grain of salt, meaning you can easily toss a factor of 50% to 75% of the rated power output if at 20 Hz. Use that power and do some sims using box modeling software to see where the chips will fall.
 
#13
tvrgeek said:
Not me, Mother nature. Physics does not change because of your viewpoint. Sorry. Do some reading on the subject.
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No sir you have proposed a copout or an easy solution to something that only solves the problem if a person doesn’t wanna put in the effort to get anything otherwise out of it. At the end of the day what you’re suggesting is fine for a person who just wants to get sound to the room and be done with it and not deal with any hassles.

Anyone willing to or more interested in it especially if it’s making their own subwoofers and what not and they’re already motivated to do much more and experiment with what will inevitably end up as something that isn’t going to change physics or be anyone’s viewpoint it will be whatever it is which very much can bAnyone willing to or more interested in it especially if it’s making their own subwoofers and what not . There’s only so many ways you can argue with a person who prefers a sealed box none of them makes sense to the person who has a sealed box it’s a turning point in effort both in coordinated into the room and in making anything else otherwise.

and most of that is exactly motivation or laziness and since no one is lazy they’re just busy with other things and life is busy so so you’re busy and you have sealed boxes unfortunately. Nothing wrong with it they sound really good And nothing to argue there however there’s more to it than just sounding really good for some people and you’re not going to be able to win that argument because it doesn’t have anything to do with physics but physics will create the end resulAnd nothing to argue there however there’s more to it than just sounding really good for some people and you’re not going to be able to win that argument because it doesn’t have anything to do with physics but physics will create the Evitable result where you have to go sit in the corner and take a time out. But don’t worry physics didn’t change and neither did my viewpoint I’d be happy with both . and I will bring you a cold drink and sit in the corner with you and will listen to them and enjoy them all.
 
#14
Booger, I (often) have a hard time understanding what you are saying. Part of that is your stream-of-consciousness style, but that usually isn't a problem for me; I can skim with the best of them. Instead, there seems to be a lack of care with your writing. Do you proofread your posts before submitting them? For example, was this intended to be more than one sentence?

Nothing wrong with it they sound really good And nothing to argue there however there’s more to it than just sounding really good for some people and you’re not going to be able to win that argument because it doesn’t have anything to do with physics but physics will create the end resulAnd nothing to argue there however there’s more to it than just sounding really good for some people and you’re not going to be able to win that argument because it doesn’t have anything to do with physics but physics will create the Evitable result where you have to go sit in the corner and take a time out.
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#16
If you simulate your speaker you will get a rough idea of how much power it takes
to get to 90 dB.

Assuming you listen around 87 to 92 dB maybe Max 94 to 96 dB

likely wont need much more than 60 to 120 watts

For clean stable power with overhead , 250 watts is enough
500 watts more than plenty
 
#19
no (chompy)I agree with you 100% the thing is I’m talking into the microphone /apple phone and it doesn’t do a very good job of picking up words lately and you realize that you’re also on a timer of what you can fix and by the time you shuffle and try to figure it out, cut and paste, there’s no way to grab it all and not get bit by the timer.and I will be at some point you’re stuck with A bunch of random garbage and absolutely nothing you can do except prepare to look like a stooge again??😃
 
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