MFW-15 w/ new July 2009 amps <absolutely NO AV123 or MLS bashing/negativity!!> - Page 2

As I previously stated I did not have a hum issue with the original amp. So not being an EE I would assume I wouldn't have a ground loop issue with the replacement amp as nothing what so ever has changed in my HT system. And I have installed the cheater plug that is supposed to eliminate ground loop issues.
I did rewrap the two large wire connections with electrical tape so they are the way I found them when I opened the sub up. I routed those two wires to the left and the grey wire to the right for non ground loop issues as recommended in the AV!@# forum for good measure while I was in there. And I did install the ferrite bead clamp per the included instructions.
I have emailed AV!@# tech support with my problem but as they are not open until Monday I thought I would try here to see if any one else has the same problem and what they may have tried to correct it.
Don't get me wrong I love having my sub back in action. I had forgotten how great it sounds to have deep loud bass. But I do want to have a subwoofer without the hum.

Good deal. See what Kyle or Jess say.

Personally, if you only notice it from 1' away, I wouldn't be too concerned about it. Whenever you shift wiring around, there's always going to be a possibility to introduce hum.

Received my amp yesterday. it was a little snug (did have to hit it with a rubber mallet). I had a pretty bad ground loop hum with my original amp, but while it was out of commision I found that the ground connector to the cablebox on the outside of my house had become disconnected (I think i must have hit it with the weed wacker) so after getting the new amp I was unsure if it was going to solve it for me. Plugged it in and it is absolutly quiet with out a cheater plug.

I'm sure I'm getting into this a little late, but with threads having been removed and other forums being read only etc. it's tough to find out information:

I have one of the original MFW-15 subs. It SEEMS to be working fine, but the sad truth is that I don't use it that often. Should I be trying to get one of these replacement amps? I mean, was there something wrong with the old ones where I would need to assume that even if I don't have a problem with mine now, I will in the future? Would AV123 even give me a replacement amp if I'm not having certain problems?
Are the new amps better or worse than the old ones in terms of performance (I realize that this may call for some speculation)? In other words, is there something inherently better about the new amp, or is a properly functioning older one better and worth hanging onto.
And lastly, were the problem amps that are being replaced bad from the start, or did they just go bad eventually?
And I'd love a quick explanation of what the basic problem with the old amps was/is.
Sorry for all of the questions. I'm not looking to stir up any AV123 bashing at all (so far I've been a happy customer of theirs), I'm just looking for information.
Thanks.

Oops. After I posted the above I saw that there are a couple of AV123 threads that are unlocked and active (I had only looked at the admin message above saying that the AV123 sub thread had been removed).

Sorry about that. Mods please feel free to remove my post or move it to a more appropriate thread. I now have hundreds of pages of threads to slog through for info I guess...

jared.....long and short of it, the first batch of MFWs were fine (someone estimated the first batch at roughly 2,000 units). 2nd batch ran into issues.

Based on what I've read and heard, some "not to spec" parts were used by the amp manufacturer in the 2nd batch of MFWs (which AV123 no longer uses). That's what caused the amp problems. How many? What percentage were bad? Estimates are widely debated. I've heard 175 amps. I've also heard 300 amps.

Sounds like you're in the first batch of MFWs with the "good parts". So, if you've had no issues, you should be fine since you're in the first batch.

As far as performance differences between old amps and new amps, the new ones are supposed to be roughly 10% more powerful. But, in reality, if that's true, it really won't amount to much sonically.

Old adage applies...."if it ain't broke, don't fix it".

You should also still be under the original warranty, too.

I just received my new amplifier for one of my AV123 MFW-15 subwoofers. I also took apart the other dead one and was able to bring it back to life as one of the leads going to the amplifier board had come off.

I'm using Bass MeKaniK's "Subsonic" for this test. I played the entire song at -1 on my Marantz SR5003 with the subs at 11 o'clock gain running 2db hot and 78db for the rest of the speakers set in the AVR. The mains and center are set as small.

The system hit peaks of 120db and maybe 121 as it blinked when it hit 120 a few times because I was stupid and didn't set the meter higher. Is it really hitting 120+db? I'll never know until I get the right equipment in to check it out but still, per my neighbors it was "fu*king loud and shaking the windows pretty damn good.

The meter was set to slow and c weighting. The one with the new amp is on the right, the one I brought back from the dead is on the left. During this song the one on the right kept going no issues the one on the left cut out a few times due to heat.

While listening to the video don't expect good sound, subwoofers always sound like crap on these cheap digicam mic's and at the volume I was running at there was no way for it to sound any other way.
Also the driver excursion wasn't captured very well because the digicam has a very slow response time for it's lens.

It does show however that this driver is fully capable of moving some serious air and that once again, my MFW's are rocking the house! I get my 2nd replacement amp for the one on the left some time this week.

Sorry about the mess, we are moving things around.

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KH.....good to see (hear) you're back in biZ.

That's the reason I don't do any vids of my MFW in action. The digi-cam mic just can't portray the sound without sounding terrible. That said, you're right. The MFW can move some serious air, reach low and play loud.

KlipschHead281, That is a great cd to test the new amps

It's great to hear that the new amps (and subs) are starting to ship out. I have a new MFW-15 on order. This will be my first "serious" sub-woofer, so I'm quite excited. (I've been trying to occupy my time by getting up to speed with the Room EQ Wizard software, and my new FBD Pro EQ, but somehow that's just been making it harder to wait!)

Wow, talk about a quick response:

Dear XXXX

May I please ask if you have cable tv... If so, please unplug it and see if this eliminates it...

We have not see this in general - but no matter, we will get it right for you...

Many thanks...

mls

His idea didn't work but I was impressed with the quick response on a Saturday!

Maybe things changed with your HT equipment, but there could be something different in the house, for example an HVAC system running that wasn't on at the time you were using the bad amp due to the weather being cooler. This is why I like for people to test something while they have the problem and not later. What I would do is take that subwoofer out of the chain and plug in something else (another sub if you had one) to see if you're getting any hum. If not, you know it's not in the input signal.

First you have to come up with a repeatable scenario where you have hum and then hum then stops. If it's always 12min later, time it just to make sure. Then start trying things to see if you can get it to change.

[quote=KlipschHead281;16807866]I just received my new amplifier for one of my AV123 MFW-15 subwoofers. I also took apart the other dead one and was able to bring it back to life as one of the leads going to the amplifier board had come off.

I'm using Bass MeKaniK's "Subsonic" for this test. I played the entire song at -1 on my Marantz SR5003 with the subs at 11 o'clock gain running 2db hot and 78db for the rest of the speakers set in the AVR. The mains and center are set as small.

The system hit peaks of 120db and maybe 121 as it blinked when it hit 120 a few times because I was stupid and didn't set the meter higher. Is it really hitting 120+db? I'll never know until I get the right equipment in to check it out but still, per my neighbors it was "fu*king loud and shaking the windows pretty damn good.

The meter was set to slow and c weighting. The one with the new amp is on the right, the one I brought back from the dead is on the left. During this song the one on the right kept going no issues the one on the left cut out a few times due to heat.

While listening to the video don't expect good sound, subwoofers always sound like crap on these cheap digicam mic's and at the volume I was running at there was no way for it to sound any other way.
Also the driver excursion wasn't captured very well because the digicam has a very slow response time for it's lens.

It does show however that this driver is fully capable of moving some serious air and that once again, my MFW's are rocking the house! I get my 2nd replacement amp for the one on the left some time this week.

Sorry about the mess, we are moving things around.

Klipsch,

Nice to see you have your subs working!

Exchanged amps on friday after work. Played BD disks; Taken, Knowing, and Push this weekend. Life is good. 6 months of agony for a weekend of bliss!

I hit them as hard as a person can during that video. I probably could have turned it up a bit more more but the left one was cutting out so I felt I took it far enough. When the next amp comes I'll push them again with the same song and see how they do. I doubt I'll ever drive them that hard again during my ownership of them, that is simply a tad too loud for me.

The customer service from Kyle has been A+ is my latest dealings with AV123. I don't want to jinx it but I think things are going to turn around nicely.

Just reinstalled my amps x2. Holy christ, i cant believe how long its been. My room is rocking again!

Amp on one corner did not quite make it flush. I tried a mallet, but it wouldnt go flush. I think my screw in that corner wont go all the way in, thus i couldnt get it to "suck" in that corner when i was sinking it.

I might put some putty in that screw hole later on and see if i can force it. I think i remember an old av123 thread about doing so...

-Pike

edit: On a side note, opening that damn ferrite bead was like a rubick's cube. Kyle helped explain what i was doing wrong in about 2 minutes. Cheers.

I am belatedly going to say something nice about AV 123
and the MFW 15.

I've had two issues with my MFW -15 and each time
AV 123 responded immediately with no questions asked.

I like that.

To wit;

JAN 2008 -- purchased
OCT 2008 -- amp died and was immediately replaced.
JUN 2009 -- amp made nasty sound and blew driver
. . . driver was immediately replaced

I like that.

The MFW-15 sounds very good . . . with B&W 801 mains with Levinson amps crossed over at 40 cycles.

Yes, it does does run hot -- but not as hot as the first one --
so I put a little whisper fan on it.

And voila, No more amp problems . . . .

. . . . and if there are problems I'm confident AV 123 will fix them.

Like I said; saying something nice.

-30-

To get mine to fit I tapped it on the left side edge towards the right so it would fit into the right side as far as possible, not too hard. Then held the middle of the amp in my fingers and pressed the left side down, put a soft terry towel on the open left area and tapped it with my rubber mallet until it fit into the opening.

It took a little bit of time and will be a bitch to get back out but it did go in. I did notice a slight nick in the corner from when the first amplifier was installed so I think they are all a tight fit. I'd rather not have this little defect but only a picky person like me will ever see it.

The new amp works perfectly but does get a bit warm. I too have ordered some small fans to install behind the subs to aid cooling. My second amp is showing to be here tomorrow even though it has not been updated in days from UPS, so we'll see. I'll shoot an installation video if my wife will help me.

KH, you are the man. I'm pretty good at stuff like this but I can always go for a "how to" video! I'll be replacing two myself in a few weeks when they arrive and wont be able to live with myself knowing they don't sit flush. Thanks in advance man.

I took some pictures during the install of this one, it's busy at work but I'll try to get them posted some time today.

Here are some of the pics I took while replacing the first amp. Unfortunately my camera went from taking great pics to crap. I don't remember changing the settings but the pictures I took of the new amp installed are real dark. But the first pic represents before and after well enough except the new amp has a serial number on it where the old one did not.

Pic one, see upper left hand corner of the amp, there is a little chip, this is a B stock sub so no complaints.



Pic two, for those who wonder what it looks like naked from the back.



Pic three, original amplifier and wiring



Pic four, notice that the red and black wires for the speaker are now removable from the board itself. On the original board notice they are soldered. The red and black wires are terminated with male plugs to meet the wire from the speaker in both the original and modified version.

Also, take a good look at each connection, very nice work, much shorter connections for each part and protected with a plastic sleave on every part. MUCH better workmanship than the first version.



Pic five, I cleaned up the wiring by re-routing the cables so they are behind the new ferrite connector. I tied them together so they aren't all free to dislodge themselves.



Sorry the other pictures didn't turn out for crap. I'll document better when I install the second amp which just showed up looking like someone at UPS was angry, NUTS!

Those photos of the new vs. old amp almost have me ordering two MFWs right now.

I know it was a long time coming but it looks like you're now getting more than you paid for. edit: I now clearly see that the middle board isn't a power supply board. It's definitely the amp board itself. Still wondering about the other boards though!

I'll look at the one I just got but I believe the board I pictured is all that was re-worked. I'll verify when I open the box shortly.

Booya! KH, can you show what the wire "re-routing" that was supposed to get rid of the hum should look like the second before the amp is re-installed? Thanks again man, keep the pics coming!

Got my amp in and working....Now running a Dragon, and an Mfw 15 in my 2200cu ft room.....my ears are bleeding.


Watched TDK tonite with a couple friends of are......jumped up several times....with the surprise bass hits so hard it felt like the couch getting kicked!

I'll be honest, all I did was make sure the wires coming from inside the cabinet were tucked away to the left to avoid the transformer.

I'll take a pic before I bolt in the new one, the 1st one has zero hum.

I hope they are doing this when building the new subs. I guess I could always open it up and fix it myself though.

This time I actually added two cable clamps inside the box to hold the wires left and right.