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Old February 19, 2009, 08:54 PM
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Default Jab-Tech vs. Petras low speed yates.... a deep look.

quoting this for my buddy nd4 ;) interesting info you guys should take a long hard read about

Jab-Tech vs. Petras low speed yates.... a deep look. - Overclockers Forums
Originally Posted by nd4spdbh2 View Post

Well guys that's right I'm bringing this up yet again. My curiosity has caught the best of me and i have decided once and for all to have a look at some yates bought at the same time and manufactured very close together from both stores... Petras Tech Shop and Jab-Tech.

A coupla days ago i made a thread HERE Showing how some OPEN cornered low speed yates i bought from J-t a while back (~ 14months ago) had smaller 25mm motors, a common size found in 80mm fans. Turns out those fans had come from a bad batch and thus is why they had horid motor ticking issues. Our Jab-Tech rep "jabtek" here at ocf was kind enough to send me replacements... 2 closed cornered, and 1 open cornered D12SL-12 yate loons. Thanks man!

I also purchased 2 closed cornered D12SL-12's from petras tech shop, and received my petras and J-T yates as well as a Nexus D12SL-12 from IKIKUINTHENUTZ today in the mail, THANKS ANDY! it was like Christmas when i got home from classes.


The nexus will not be directly compared as it is a "different fan" but i will put notes about it where applicable.

So i took my three boxes up stairs and proceeded to open them.

Proof of purchases (areas blacked out for security purposes / information not made to the public)

In total i had 5 new fans and one slightly used one (the nexus)... Before taking them apart i carefully listened to each one making note of their noise characteristics and anything out of the norm... I used a NON PWM power source to power the fans, as a PWM type current can sometimes make normal dc powered fans exhibit weird acoustics... All fans tested at the same voltage... we will get to the details later in the conclusion.

Top Side

As you can see in the picture below i have the petras fan on the left and the J-T fan on the right. At first glance there isn't much of a diff besides the sticker missing from the hub of the fan assembly on the petras fan also i noticed that the 3 wire leads from the fan are about 5 inches longer on the petras model than the J-T one. I will be comparing all closed cornered models for this.

Bottom Side

In this picture every thing is lookin the same, we have 3 rounded spokes and 1 flat spoke for the wires. But If you look closely at where the green arrow is pointing you will notice something. The jab-tech fan has a very visible lip running that entire ring around the fan... the petras yate does not. and its not just the picture making this difference its a very real physical difference. Note- the Nexus has 3 triangle shaped spokes and one flat spoke for the wires.

Production Dates

Now some may say - "well maybe these fans were made at very different times" ... they were made ~4 months apart which isn't much of a difference.

Its actually year/month but we know what you ment as in that quote he was referring to my bad yate loons with a date code of 709 ... 2007 9th month (september) that i bought back in November of 2007.

Here are the yates from petras and j-t... all the yates from petras had the same 901 date code January 2009... and j-t's a 809 date code.... September 2008.

Hub and Blades

I also noted another coupla differences is at the hub and where the fan blades meet the hub. 1 - The petras hub corner is a nice rounded shape whereas the j-t hub is a hard corner with a slight bulge. 2 - The petras fan has a nice gusset where the blade meets the hub whereas the j-t fan does not. There is a gusset on the underside of the blade on the petras and the j-t fan, but both the topside and underside gusset on the petras fan is much bigger than the j-t fan's only underside gusset. (didn't see it necessary to take a pic of the underside of the blades) I will note that the nexus fan was very similar to the j-t fan in that it only had an underside gusset but it was the size of the petras gusset and not small like the J-T gusset, the nexus also had a rounded hub corner like the petras yate.

Time To Take Em Apart!

Thats right it is time. I took all three fans apart, i was mainly looking for motor size as this might explain differences in acoustics. The fans are very simple to take apart, peel back the sticker pop the rubber seal, pop off the plastic clip and the blade assemble comes out.

Now if im reading mr jabtek's words right from this quote ...
This means that the Low speeds should have a smaller 25mm motor.

Lets have a look see...... whats that, the nexus and petras both have the bigger 30mm motors, and the jabtech has a punny lil 25mm motor commonly found in 80mm fans... and yet they all have the same sleeve bearing size HMMMMMMMMMM

Closeups of the motors.... The nexus and petras fans have literally identical 30mm motors, the only difference i noticed is that the nexus has 4 extra resistors before each coil to reduce the voltage fed to the coils thus reducing the speed of the fan and an extra capacitor or two... then we have the J-T fan that has a lil itty bitty 80mm motor. Also if you look closely at the iron cores of the nexus / petras fan you notice that the faces are notched and angled in the direction of the rotation of the fan, obviously to aim the magnetic field... this is non existent on the j-t fan.


I told you i would get to the acoustics didnt i. Well its pretty simple... the nexus wins out of them all and its obvious why... it spins slower and has capacitors to smooth out the voltage fed to the coils... but this fan is not part of our explicit comparison.

The fans from petras sounded exactly the same when comparing them to eachother, as did all three of the jab tech fans when comparing all 3 jab techs to one another. The difference is when you compare a Petras yate, with a J-T yate. None of the fans had any bearing noise what so ever, and being that the overall blade design was essentially identical the only acoustic differences could come from the motors / hubs them self's.

The petras fans were very quiet... an almost inaudible soft clicking could be heard if you put your ear 6in away from the hub on the exhaust side but couldn't it was very hard to hear even at that close of a distance. This is not the same for the j-t fan. The j-t fan was much more clicky, more pingy in fact. The clicks were much more pronounced and able to be heard much further away. Its obvious the motor difference has something to do with this, and it also seems like the void that was created in the hub of the J-T fan to mount the smaller circle magnet produces an amplification / echoing effect of the clicking of the smaller motor.


It seems as though petras and jab-tech get their fans from different sources. Petras has repeatedly stated and confirmed that they get their yates from yate loon DIRECT... so where jab-tech gets them is anyone's guess, but one thing is for sure... j-t's fans are of a cheaper quality, using smaller 25mm motors, and poorer manufacturing processes as indicated by the differences in the hub, fan to hub connection, and frame. And this cheaper quality is very much apparent in the acoustics of the fan.

My ears and the pictures dont lie... The petras closed cornered yate is by far better... the petras yate takes the best from the super duper well respected for its quietness nexus fan and is produced for the cheap.

So in the end ill let you guys decided, do it your self buy a fan from j-t and petras and see which one you like the best... or simply look at my in depth analysis of these fans... alls i know is that petras will be the place i get yate loons from now on.

I would like to thank Andy (IKIKUINTHENUTZ) for sending out the nexus fan. And J-T for sending out replacements of my bad yates i bought 14 months ago.
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