Question about FST midrange drive unit

[weijst]

Hi all,

I'm a little worried about the FST midrange drive units in my demo 804's which I recently purchased and I was hoping someone out here could help me:

1. The plug in my FST midrange is not perfectly centred / is not located in the middle of the black ring. The distance between the plug and the black ring varies from roughly 1 to 2 mm. The dealer I bought them from told me to tighten the plug a bit (assuming the screw thread is perfectly centred), but since it's already tightened and the only way to tighten it more is to apply considerable force, I'm doubting his advice...
   
2. The black ring itself is not a perfect circle. Not that it's square or anything, but it seems to be very slightly dented...

Since sound waves are supposed to move move away from the cones in circles, I was wondering if these aspects don't influence the sound negatively.

Bottom line: I'd like to find out if both mentioned aspects are 'normal' or if there are FST midrange drive units out there with simular characteristics.

At first I was rather happy with my purchase, but as time is passing, I'm noticing little things that make me wonder if these are really the speakers the guy had promised me and what I've payed for (e.g. the serial nr. already turned out to be far too low for an actual 1,5 month old 804...)

Any feedback would be appreciated.

Thank you

[RobP]

That plug should be perfectly centered in between that upper wall of the voice coil. By looking at the picture one of three things could have happened. First, when the driver was manufactured the voice coil could have been glued slightly off level on the spider. or when the cone assembly was dropped into the gap the wrong shim stock or no shim stock was used to center the cone and VC. Or I have seen woofers and drivers that were overdriven to the point where the surround matierial became weak on one side (usually the bottom) and the cone actually becomes warped on the vertical plane. But with the nature of this driver I would go with the first two causes. I would have the dealer replace the driver.

[caleb]

Don't get hung up on appearances - it's what the speakers sound like that should be what you are worrying about.
Caleb

[weijst]

They sound pretty good (especially the low regions, thuh ). Compared to my 705's that is, since that's the only AB comparisson I can really make at the moment.

A demo session with another pair of 804's and the dealer's comments the ones I was going to get had been playing for just 1,5 month and that there was absolutely nothing wrong with them had me make a downpayment on these 804's, which I hadn't seen at that moment. I was willing to pay more for them compared to other occasions BECAUSE I was told these were just 1,5 month old.

The disappointments started after they were delivered to my home 4 days later... The low serial number and the colour of the kevlar cones are already a point of discussion as we speak. The mentioned aspects of the FST midrange drive units are just another reason for wondering if I'm not better of sending them back to the dealer and postpone my entry in the Nautilus range .

[aphexist]

How do you know that number is too low to be in use for 1.5 months? They might have been in the box for a year before he put them out as a demo.

Also, I wouldn't worry about the miniscule separation you are fretting over. Assuming there is a minor cosmetic problem on the outside speaker, how can you know that there won't be a major functional problem on the inside of a replaced midrange? The flaws that you can hear are the only ones that matter when it comes to things like this.

Lastly, you knowingly bought a demo unit. It has been on a showroom floor for some time, and has been handled, groped, fondled, and possible humped by other customers almost every day for the last month and a half. If you want untouched speakers, buy them new-in-box.

[weijst]

Thanks for your input aphexist.

How do you know that number is too low to be in use for 1.5 months? They might have been in the box for a year before he put them out as a demo.

I was promised (and paid for...) 1,5 month old speakers that stood in a B&W rep's living room after rolling out of the factory in the UK. Some research plus an inquiry for the manufacturing date at B&W resulted in an age of 3,25 years... Ofcourse I wouldn't have said anything if they turned out to be say one year, but 1,5 months <=> 39 months is to big a difference to ignore...

Also, I wouldn't worry about the miniscule separation you are fretting over. Assuming there is a minor cosmetic problem on the outside speaker, how can you know that there won't be a major functional problem on the inside of a replaced midrange? The flaws that you can hear are the only ones that matter when it comes to things like this.

I wouldn't have mind minor 'cosmetic problems on the outside' like (e.g. scratches). It's when these so called 'cosmetic problems' might influence the speaker's performance when I get worried...

Lastly, you knowingly bought a demo unit. It has been on a showroom floor for some time, and has been handled, groped, fondled, and possible humped by other customers almost every day for the last month and a half.

Not really, I paid for a unit that stood in a B&W rep's home for 1,5 months. I wouldn't have gone along with a demo unit (which meant the unit had been moved around a lot). The dealer knew this...

If you want untouched speakers, buy them new-in-box.

Yes, it is not a new unit. I was indeed willing to accept some traces of usage. However I payed more than your average occasion because I was promised more than your average occasion... Point is I'm not convinced at all this is what I got...

[jlee]

I have observed several new Nautilus speakers (including the 5 that I have) and ALL of them were not PERFECTLY centered. 1mm on 1 side and 2mm on the other side is perfectly normal (anything more than 0.5 to 1.0 mm difference and I would be concerned). The bullet should be HAND tight only... do not crank the crap out of it. And yes, the ring that goes around the bullet also does not need to be perfectly round. I have checked this on speakers from 805 to 800 Signature... the ONLY one where I have seen something awkward was on a demo HTM2 where the bullet was almost TOUCHING the ring... and in fact WOULD TOUCH the ring during deep bass and the driver moving a lot... you could actually hear a fluttering noise. This was a demo and I mentioned this to the dealer. I think a previous customer who borrowed it abused it.

[kate]

:cry:

That is not nice

I can imagine it is a terrible feeling ,having first been extremely happy and now to have been let down.
I hope the hifi shops comes to an agreement with you that will make you happy.....

any more news?

[caleb]

Weist,
This puts a different emphasis on the story.
Your gripe I think is well founded if you have been hoodwinked into thinking the speakers were 6 weeks old and they turn out to be 3 1/2 years!!

Aside fron the fact that they may sound O.K. your guarantee will be reduced accordingly.
Also the Kevlar cone of the FST should be quite yellow - if it has started to go brownish then I would have those speakers back to the dealer with a shoptgun in my hand - he has puilled the wool over your eyes so get your moeny back.
Caleb

[weijst]

Thanks people,

Jlee, regarding the 'cosmetic appearances', I guess that's what I needed to hear...

Kate, thanks for your support. How's your search going? Have you already heared those 804's sing in your room?

Caleb, regarding the age of the unit (and guarantee), let's see what the dealer is willing to offer me (expecting a phonecall any day now).

[DanR]

The centering of the phase plug is rarely exact. As far as the faded yellow, that seems to be a problem. I would definitely send them back. My N802's are 4 years old and the FST's are still a bright canary yellow.

[caleb]

The biggest problem with Kevlar as a fibre is that is does change colour particularly when exposed to sunlight (UV content) - then it goes from yellow to light brown.

The performance however does not really deteriorate.

Therefore "old" FST units that have seen sunlightdo tend to loose their light yellow colour.