12V DC pump at DangerDen
 

I´ve been staring at this graph, describing the caracteristics of a 12V pump (called DD12V-D4) at DangerDen (I cut the pic from www.dangerden.com), but I have some trouble interpreting the graph.
Is this a great pump, a so-so pump or most likely plain BS?
regards
Mikael S.

Read this thread:

http://forums.overclockers.com.au/sh...hreadid=244231

Pretty much answers your questions, plus gives additional data obtained from real-world testing.

Thanx, Cathar!
As reliable information source as always!
regards
Mikael S.

its going to be interesting how 'consumer' watercoolers take to this, especially when Cathar recently reported higher noise levels- 45db for a pump is pretty high, at least for me
I'd buy it though, for the good graph

Could someone do me a massive favour and email me, guan_di AT Hotmail.com with a copy of that thread please, i dont pay £20 a year for a "free" hotmail account, so OC.com.au can go fsck a roo if they think i am getting another account just for them :mad:

it appears the price is going to be $74.99 - only appears on their site as part of this kit atm

well it's now on the site proper... they are going to offer the 3/4" fittings also :)
http://www.dangerden.com/mall/Pumps/dd12vd4.asp
their claimed sound levels are here...
http://www.dangerden.com/images/pump...d_chart_lg.jpg

*snort*

That data would place the Laing D4 at a mere twice the volume of an Eheim 1048.

No way on our green earth is that true.

Perhaps if they sat the Eheim 1048 resonating heavily on a piece of wood and then took the readings....

The Eheim 1048, if not vibrating on something, is near totally inaudible at 12".

Secondly, and as a bit of an eye opener for those who know their physics, the sound pressure level drops off at an inverse square to distance.

If sound is being properly measured at 1x distance (12"), then if properly measured at 3x distance (36"), then the sound level would be 1/9th the amount at 12" distance.

The dBA scale is a log-base-10 scale. This would mean that at 36" distance, the dBA level would be 9.5dBA lower than at 12" distance.

Now take a look at the Eheim 1048 lines again, and we see a 2dBA separation between 12" and 36".

Primarily the results don't match any form of understood physical theory.

Secondarily for there to be such a small difference, one would have to assume that the Eheim 1048 was vibrating against a larger surface and at 36" vs 12" distance the actual distance of the sound-meter from the thing making the noise (whatever the 1048 was sitting on) did not really change much at all.

As we all know, it is possible to construct tests to suit our needs. Its the issue of making it believable that's the problem.

Actually they are running into a problem known as the noise floor. Or the sound level of the empty room without the pump running.

Since I'm not awake yet I won't try and go into exact numbers but this background noise will compress all readings as you get closer to it. My math escapes me at the moment but I'm sure someone else can help out.

You just couldn't measure 9dB below 35dB. As the background noise of most quiet rooms is around 30dB.

Companies use an ancheoic chamber to lower the ambiant noise so that one can measure sound levels lower than the normal background noise of a room.

hmm - looks like they're admitting to considerably more than double to me: 35dB for the 1048 (at 12") and 43 for the d4@12v would be +8 dB which is over 6x i think????

the jumps to 36" don't stand up.... unless "decibles" isn't a misspelling of "decibels" but some new unit... ;)

the claimed drop between 11 and 12v seems very odd...

i did think that putting the dB comparisons at the bottom to leave the casual viewer with the impression a university had tested the pumps was a nice touch...

Hmmm, that may be.

Still though. If I run my Laing D4 at 12V in my office sitting on vibration deadening padding on the floor, I can still clearly hear the whine when sitting in the loungeroom, which is 25' away through two (open) doorways with the TV on during quieter lulls in the TV volume - as in whenever the TV goes quiet(ish), I can immediately hear the pump's whine.

Now how many people who own an Eheim 1048 (I do) can ever say that their 1048 is even one half as loud as that?

The human ear perceives each +10dBA as a doubling in volume.

ah - i follow what you're saying then (presumably that's why loud headphones are so bad for hearing then as the spl increases so much faster than the percieved volume....)

did your pumps come with the pump support or anything similar?
http://www.dangerden.com/images/pumps/12v/d4_sm.jpg

Nope. No supports for me.

its too bad those things are loud as hell when they're in full blast.

any how, whats the performance curb at 6v?

At 7V, very slightly weaker than an Eheim 1048
At 6V, significantly weaker than an Eheim 1046

thanks for the info mate.

thats too bad for me, that pumps is just too loud for my taste.

flaky graph, Temple University ??
bah
not addressed at all, other than by Cathar as usual, is the pitch of the noise from the D4;
different frequencies 'carry' more than others, lower being less pervasive and objectionable than higher
the "A" curve (as in dbA) measures spl over a specific range, a high tone/whine can 'sound' louder than the dbA rating might suggest

pump users will sort this out pretty quickly

if they're not scared off by the noise.....

your confidence expressed earlier this month is becoming ever more understandable... ;)

So this pump is much noisier than the L30?

If you got the choice, which would you choose? Noise levels take priority over performance here...

And seeing as to how I can get the L30 locally for $40...

If noise is your top priority then I think my Eheim 1048 is about the quietest pump I own.

I have 2 d4's in brass on order. The fittings are 1/2 sweat. Pricing is about the same as the noryl model. It'll be interesing to see if the brass head effects noise at all.

JR

hmm
how you planning on comparing the noise from the brass heads to that of the plastic ones then ?

DOHHH??!!! Hadn't thought about that. It'll be based on how much hair I loose whilst trying to make them quieter I guess....LOL point well taken

JR

After much mathamatical debauchery I have come up with a formula that proposes that: For every 3db above the ambient noise floor I rip aproximatly 50 hairs from my head. Therefore assuming a noise floor of 30 db, 30+200 hairs=42db. Elagant in its simplicity isn't it LOL