One of my Sequels is sick :(

[Beat_Dominator]

This morning I put on some rocking music as I got ready for work. It was loud, but not by any means excessively so.


I go back into the room to get my shoes.... and the woofer in my right Sequel is distorting like crazy

I had to leave so I just turned everything off to await my return so that I can get down to diagnosing the problem.

I have only 2 possible causes:

1) My amplifier is losing the right channel and sending distorted, low frequency signals to the speaker (not too likely).
2) The right woofers suspension came unglued or is torn. If the coil was blown (which would require clipped signals from the amplifier) the sub would most likely not move at all.... and it still moves, though it sounds terrible!

Such is life with 18 year old speakers

 

[IWalker]

hrm, strange. Sounds like your surround might have come unattached?

 

[lugano]

Switch the cables at the amplifier's outputs (exchange left with right) to exclude any problems coming from the electronics. If the problem stays the same, then it's definitely the woofer. If you have to change it, I'd suggest to order 2 of them and change the other one, too, for obvious reasons.

 

[twich54]

i concur with Lugano, espescially considering they are 18 years old.

 

[Beat_Dominator]

Yeah that's my plan for tonight. I was going to replace them anyway down the road.....I guess the MLs decide when to update

 

[IWalker]

there isn't an easy way to take the grill off is there? If there is, you can just pop that off first, and see if there are any visible abnormalities, even before testing the amp. If nothing's visible, then certainly test all other pieces before deciding to scrap the woofer. Often times, if a surround comes off (but hasn't decayed) you can simply reattach it with some contact cement...voila.

 

[Beat_Dominator]

I can remove the grill easily. We shall see what awaits!

 

[Joey_V]

Good luck Evan!!! Keep us in the loop as to what goes on in getting the Sequel back to health. :cheers:

 

[JonFo]

I Hope it's nothing, but my money is on blown woofers.

At 12 years, woofers are long in the tooth, at 18, well, MTBF hits.

 

[Beat_Dominator]

Mystery revealed!

I had to run my speaker cables to the sub woofer binding posts and take the jumpers out to figure this one out. I played the song that I had on when I discovered my woofer issue..... lo and behold it was the dust cap that was the culprit!

Looks like some industrial strength contact adhesive is all I will need to keep me happy until I'm ready to change out the drivers!

 

[IWalker]

glad to hear that's the only issue! good luck with the contact cement. Let us know how the repair job turns out.

 

[Tube60]

Instead of contact cement, I'd suggest Ailene's Tacky Glue from the craft store. It's similar to what the OEMs use, and it's really forgiving before it dries. I used it on my Sequel's woofer surrounds to glue them back onto the baskets, and to seal up a slight tear in one of the surrounds as well. So far, so good! I haven't had any separation issues yet.
HTH!

 

[johnwa]

I Hope it's nothing, but my money is on blown woofers.

At 12 years, woofers are long in the tooth, at 18, well, MTBF hits.

Sorry to go off context here but Jon, could you please supply the specifics on the woofer exchange you did on the Monolith"s? The supplier and instructions would be very helpful as I plan on following suit. I will be right behind on the Sequel's as well.

 

[JonFo]

Beat Dominator,

Glad to hear it’s simple to resolve. Although it looks like I was right about it being the woofer. If the glue for the dustcap is failing, there are surely other things about those drivers that are either failing, broke or way out of original spec.

For instance, the 12 year old Eminence drivers in my Monoliths looked fine, sounded sort-of OK (no glaring audible distortions), but were really crap when measured. The compliance of the surrounds and voice coil spider was very different at 12 yrs of age and the speaker had high THD when measured.

The swap in of the new units made a night and day difference.

JohnWA, I documented the models and process of the Monolith woofer upgrades in this thread:

http://www.martinloganowners.com/~tdacquis/forum/showthread.php?t=2025

For Sequels, we still need to identify a suitable replacement driver. I’m planning to do mine sometime in the next 12 months when I repanel them. It’s just that I keep getting tempted to build another couple of mid-bass Line Arrays for the Sequels instead of replacing the woofer. Decisions, decisions…

 

[Dreamer]

I had a similar problems with my "right" Sequel a few months ago. Not a really bad distortion, just an annoying little buzz on some music--not all the time either, just with certain CDs.

Turns out it was the cardboard ring that is on top of the edge of the surround that had come loose in a few places. Some VERY judicious application of cement fized the problem right away.

BTW, I called Martin Logan to inquire about replacement Woofers, and they have ones that will work with the older Sequels, but they are a much newer version. They are supposed to sound VERY good, and if I remember correctly, it was going to cost about $165 for a pair (plus shipping). Seems like a REALLY reasonable cost for what would be a pretty substantial upgrade...

I may replace my woofers anyway (even though I was able to fix it) because my speakers, like yours, are almost two decages old. I mean, it can't hurt, right? Plus it will increase my resale valuse when I decide to replace them with something a little more new.

--Richard

 

[Beat_Dominator]

JonFo, I have really thought about replacing the woofers in my Sequel IIs with an aluminum coned woofer. I am not at all impressed with the "technology" of the late '80s composite cone in there now.

When I had taken my panels off to shower them a few months ago I wiped down the woofers (they were very dusty) I discovered that they were unbelievably flexible, the cones that is. A paper cone is usually more stiff than what the OEMs seem to be.

I would love to know a few of the T/S parameters of the OEM drivers to better match them to a replacement, but in all likelihood; if I match the impedance, size, and preferably xmax closely, the slightest change in Sd and resonant frequency will make only a few Hz difference in x-over point. There is also plenty of stuffing in the cabinet where I could add/remove some to get a desired result.

As you are the resident DIY speaker man..... what are your thoughts?

 

[IWalker]

Can you try to get an estimated measurement of the internal volume of the enclosure? There are a ton of good drivers out there that could replace them, without much of an issue, though you would need to match the sensitivity of the new driver to the old one (unless you're going to bi-amp) or else your sub section will run either "hot" or "cold".

 

[lugano]

Beat, I'm really happy to know that you managed to nail down the problem.

While I basically agree with IWalker about putting in better woofers, my common sense reaches for the alarm signal: if you want to sell them tomorrow or later, the buyer might question your choice of a "better" woofer, and you risk getting less for them, having spent more. And of course you also risk building a Frankenstein, totally out of control and not obeying to the original ML calibrations and intents.

To make it short, I would rather follow the leader on this one and use only original replacements from ML.
My 2 cents, of course.

 

[JonFo]

JonFo, I have really thought about replacing the woofers in my Sequel IIs with an aluminum coned woofer. I am not at all impressed with the "technology" of the late '80s composite cone in there now.

When I had taken my panels off to shower them a few months ago I wiped down the woofers (they were very dusty) I discovered that they were unbelievably flexible, the cones that is. A paper cone is usually more stiff than what the OEMs seem to be.

I would love to know a few of the T/S parameters of the OEM drivers to better match them to a replacement, but in all likelihood; if I match the impedance, size, and preferably xmax closely, the slightest change in Sd and resonant frequency will make only a few Hz difference in x-over point. There is also plenty of stuffing in the cabinet where I could add/remove some to get a desired result.

As you are the resident DIY speaker man..... what are your thoughts?

I would first call the factory and see if you can get the T/S parameters for the woofers. They usually will send you a fax or email with them.

The hardest part about a woofer swap will be getting exact match on volume and phase. As you note, if you are close on the T/S, the x-over point won’t be a big concern.

But a phase variance of 90 degrees sure would, or an efficiency difference leading to a 3dB variance in output. This is why when I tweak, the first thing to go is the passive x-over, and in comes a speaker processor and an extra set of channels of amplification. This mitigates all those concerns.

Therefore my recommendation is that for the $165 they quoted you at ML for the factory replacements, just get that. Plug and play, and as Lugano points out, fewer explanations during resale.

 

[IWalker]

ah...yeah, if you can get ML replacements, do that. If for resale value if nothing else. That's why I've never modded my Quests at all. I've just unplugged the woofers, and connect the other stuff through a speaker processor. You could always do that...and then go CRAZY like JonFo (for his awesome center channel) and I have and take the woofers completely out of the equation! Arrays+Subs!

JonFo's comment about phase is absolutely correct as well...and is commonly ignored (to ill effect) ...another reason to get the factory replacements.