Grille covers on or off

[Franin]

Apparently you have never seen a Fathom grille. The Fathom grilles are made of a good grade ABS plastic and covered with grille cloth. The structure is very strong and if the driver impacts the grille as apparently is happening with Franks unit, it would make a sound. I may have heard the same sound when I had my Fathoms.

Hi rmk, hopefully I will be talking to them tonight.

 

[rmk]

Hi rmk, hopefully I will be talking to them tonight.

Hi Frank,

It may also be that your AS-EQ1 has your Fathoms boosted a little too much in the low frequencies and the Fathoms are simply being over driven. That creates tapping noises that can sound like grille impact. We had a GTG at my house a couple of years ago and both my Fathoms and a pair of SVS PB13’s were too easily driven into over excursion related distress. I sold my Fathoms due to this and now have a slightly over the top sub system as a result.

If JL doesn’t come up with something that works, you may want to try re-running the AS-EQ1 software. If that doesn’t work, you may need to drop the subs level on your Denon. Actually, that would be a good first step as it takes no time.

Good luck,

Rob

 

[Franin]

Hi Frank,

It may also be that your AS-EQ1 has your Fathoms boosted a little too much in the low frequencies and the Fathoms are simply being over driven. That creates tapping noises that can sound like grille impact. We had a GTG at my house a couple of years ago and both my Fathoms and a pair of SVS PB13’s were too easily driven into over excursion related distress. I sold my Fathoms due to this and now have a slightly over the top sub system as a result.

If JL doesn’t come up with something that works, you may want to try re-running the AS-EQ1 software. If that doesn’t work, you may need to drop the subs level on your Denon. Actually, that would be a good first step as it takes no time.

Good luck,

Rob

Hi Rob
Without the covers it works fine, I was more curious if I was damaging my subs if it pulls out the Excursion that far. That tapping from tightening the screw was the glue seal.From talking to them the Excursion is designed to handle a good amount but Im the first to bring up this so called problem. There going to run some tests to see exactly what the problem is.

 

[rmk]

Hi Rob
Without the covers it works fine, I was more curious if I was damaging my subs if it pulls out the Excursion that far. That tapping from tightening the screw was the glue seal.From talking to them the Excursion is designed to handle a good amount but Im the first to bring up this so called problem. There going to run some tests to see exactly what the problem is.

I forgot the grilles off, no issues part

It would be ironic if my Fathoms "sub bottoming" issues were just the driver hitting the grille's. I kept the grilles on all the times and never considered that as a possible issue. JL didn't either.

Please keep me posted as to the outcome.

 

[Franin]

I forgot the grilles off, no issues part

It would be ironic if my Fathoms "sub bottoming" issues were just the driver hitting the grille's. I kept the grilles on all the times and never considered that as a possible issue. JL didn't either.

Please keep me posted as to the outcome.

Like me you would not think that could be a issue, but it was (For me)

Look at the bright side it gave you an exscuse Rob to get yourself some good subs.

 

[rmk]

Like me you would not think that could be a issue, but it was (For me)

Look at the bright side it gave you an exscuse Rob to get yourself some good subs.

Yeah, I have always wanted subs that could structurally damage my house ... I'm there now.

 

[AcuDefTechGuy]

I firmly believe that my speaker grilles should stay on.

 

[MidnightSensi]

Hi Frank,

It may also be that your AS-EQ1 has your Fathoms boosted a little too much in the low frequencies and the Fathoms are simply being over driven. That creates tapping noises that can sound like grille impact. We had a GTG at my house a couple of years ago and both my Fathoms and a pair of SVS PB13’s were too easily driven into over excursion related distress. I sold my Fathoms due to this and now have a slightly over the top sub system as a result.

If JL doesn’t come up with something that works, you may want to try re-running the AS-EQ1 software. If that doesn’t work, you may need to drop the subs level on your Denon. Actually, that would be a good first step as it takes no time.

Good luck,

Rob

I would think the Fathams would have gain modulation and excursion protection, considering they are servo-driven. I'm surprised you can drive them to over excursion, I would expect it to just hit a limiter or protection circuitry.

Your Crest CC amplifier has IGN (instantanious gain modulation) and ACL (active clip limiting) and will save itself and the speakers from damaging clipping by lowering the input attentuation temporarly. Then you can set the limiter on your QSC DSP to prevent overexcursion. So, basically, the way you have things setup now, even if you did drive your subs to overexcursion, it should only be once because you can then set the limiter a bit below that threshold.

I say that to say this: For what a Fatham costs, this should be included in the built in amplifier.

It's a bummer to watch a movie worrying if your subwoofer is going to make funny noises. I can't stand that and think any good active subwoofer should have protection built in.

 

[rmk]

I would think the Fathams would have gain modulation and excursion protection, considering they are servo-driven. I'm surprised you can drive them to over excursion, I would expect it to just hit a limiter or protection circuitry.

Your Crest CC amplifier has IGN (instantanious gain modulation) and ACL (active clip limiting) and will save itself and the speakers from damaging clipping by lowering the input attentuation temporarly. Then you can set the limiter on your QSC DSP to prevent overexcursion. So, basically, the way you have things setup now, even if you did drive your subs to overexcursion, it should only be once because you can then set the limiter a bit below that threshold.

I say that to say this: For what a Fatham costs, this should be included in the built in amplifier.

It's a bummer to watch a movie worrying if your subwoofer is going to make funny noises. I can't stand that and think any good active subwoofer should have protection built in.

It was surprising to me that the Fathoms could be over driven and when I first spoke to JL about it they were in denial. They, then confirmed it on some suggested movie tracks but the only solution was/is turn the levels down. If the distress is excursion related with the driver hitting the plastic grille, that is just a poor design and JL should come up with a fix.

I think a desire for performance plus not knowing what Hollywood was doing with ELF in movie sound tracks caught them by surprise.

 

[Franin]

Been playing around with the system last night. I took the sub away from the sidewall and placed it on the front facing me like the other one. made sure the distance on both is the same etc. I even moved my seating and had to redo audyssey and the sub eq audyssey and was very pleased with the outcome. For some reason the sub on the side wall must be in a null or something because it seems to work harder but on the front its fine.I guess its one of those mysteries.

Its amazing how moving the seat can make such a difference also. I used to have a dip in the 48hz -50 hz range but know it seem to be more improved given me a flat response.Still intrested though to find out what that noise was. Watching some JL audio subs W7 on youtube there excursion seem to rise quite a bit.

 

[Franin]

I would think the Fathams would have gain modulation and excursion protection, considering they are servo-driven. I'm surprised you can drive them to over excursion, I would expect it to just hit a limiter or protection circuitry.

Your Crest CC amplifier has IGN (instantanious gain modulation) and ACL (active clip limiting) and will save itself and the speakers from damaging clipping by lowering the input attentuation temporarly. Then you can set the limiter on your QSC DSP to prevent overexcursion. So, basically, the way you have things setup now, even if you did drive your subs to overexcursion, it should only be once because you can then set the limiter a bit below that threshold.

I say that to say this: For what a Fatham costs, this should be included in the built in amplifier.

It's a bummer to watch a movie worrying if your subwoofer is going to make funny noises. I can't stand that and think any good active subwoofer should have protection built in.

Im sure they should have some protection. When I took the cover off and watched that particular scene the Excursion came out but nothing too out of the ordinary and it sounded great without the covers. the Excursion is quite big on these units and if you look at the space between that and the grille there is not much at all. And the grille doesn't help having plastic throughout the front. From what Ive seen on there demo and You Tube regarding there W7 sub no one has a cover. Even when speaking to the gentlemen at JL, He was under the impression that most forum people take the covers off.