Sequel Twos sound like they are unplugged

[max_dvdt]

Hi,

I have had a set of Sequel IIs since about 97, I used them for about 5 years. For the last 4 years I have had them turned off, sitting in the corner... (someone decided they just didnt look good when properly placed so we had a 4 year "music out"...)

My old friend and audio mentor is coming to visit so I dusted things off and tried to fire them up... and disaster... the panel portion hardly makes any sound....

This is on both speakers... Its been a while but it seems to me it sounds like they arent plugged in (but they are), I lifted the crossover cover and checked the 0.25A fuse and its intact...

I've tried this setup with the following two setups:

Marantz CD67MkII SE
EAR/Yoshino 834L preamp
and two different monoblock amp sets A) EAR/Yoshino 549 (200w tubes) B) Carver PM600 (3-400 watt bipolar)

Identical results...

I have tried the B) setup with a cheapie bookshelf speaker and everything sounds GREAT.

So the problem is definitely the panels...

any comments?

odd that both panels died... but then its been 4 years....

thank you in advance...

K

By unplugged I mean from the 120V mains, not from the amps...

 

[cyclone]

Sounds like the panels may just be very dirty or the contacts may have oxidized. Try giving them a good cleaning and reseating all the contacts.

 

[enilsen]

If I was you I would first try vacuuming the panels and see if this helps.

Assuming no audio difference is heard you could also try the water trick. This is less drastic than washing the panels, but might clue you in to failing connectivity between the bias metal strip and the diaphragm. (Note this has been suggested on other sites that the aluminium bias metal strip can oxidise over time when not in use hence copper is the preferred metal for this purpose)

Just take a plant sprayer filled with clean water and spray a small amount to the lower area of the stator so it runs down the diaphragm and makes contact with the foam spacer. If the sound returns then you can look at my posting on how to fix this problem without disassembly of the panels. Weak sounding panel repair

 

[IWalker]

I know this sounds stupid...the whole "did you turn the power on" question... but did you plug in the logans into the wall and let them sit for half an hour or so? Not sure if, after 4 years of non-use, the power cords were an after thought...

I imagine this is not the case, but it sounds to me like what you're hearing (panels have no charge)...so I figured I'd throw it out there!

I noticed your comment at the bottom...but couldn't quite decipher it. Does that mean the mains aren't plugged in, or that they are?

 

[C.A.P]

Being electrostatic I would check all wire connections first. There are 3 wires that connect the panels . I also would look at the X-overs and clean all connections with alcohol. A dirty connection or rust from condensation can wreck havoc on the panel . That being said if that still dont work try the vacuum then the last straw take them off and wash them but if you cant get sound I dont think water will help ! Look for rust or buildup any where. I can see some or low sound, but BOTH not working ! hmmmmmmmm

Good luck !

 

[enilsen]

That being said if that still dont work try the vacuum then the last straw take them off and wash them but if you cant get sound I dont think water will help ! Look for rust or buildup any where. I can see some or low sound, but BOTH not working ! hmmmmmmmm

Good luck !

The water is not a fix but to determine if the hv bias strip has lost connection with the diaphragm without disassembling the panel. The bias aluminium strip with the Mylar plastic is very similar to the mechanics of a capacitor. When large capacitors have not been used for longer periods of time they can in fact have lost the ability to insulate the metal plates thus heat up and leak or explode. Old capacitors can be rejuvenated again by applying a small trickle current over many hours with a voltmeter hooked up to monitor the charging capacity. Eventually the capacitor reaches a full charge and can once again be used without self destruction.

We are less fortunate with our panels as once the bias strip looses contact with the diaphragm sound will not be auditable. To me it is quite logical that both speakers have failed at the same time due to this phenomenon. If one had failed and not the other then I would be investigating the electronics and various connections.

 

[max_dvdt]

Clarifications...

Ok...

Thankyou for your responses..

I had gone thru and attempted to fix the potential oxidized connections on the crossover... didnt really see any problems there...

and by "unplugged" I meant the speakers sound "like they do when they are unplugged" but that they were plugged in.... and have been so for several days.

"enilsen"'s suggestion of the plant sprayer did the trick.. so my issue is contact oxidation on the film layer...

Call me "stupid" but ML is offering new films for $550 for a pair.. what is involved in replacing the films and are the new films any better with respect to oxidization?

K

 

[IWalker]

Good work enilsen!

 

[Tube60]

Ok...
Call me "stupid" but ML is offering new films for $550 for a pair.. what is involved in replacing the films and are the new films any better with respect to oxidization?
K

Funny how things like that work out.... my original Sequels sat for ten years but play just fine.
MLs replacement panels will be exactly that..... a whole assembly; stators, membrane, everything ready to go. They also benefit from ML's experience and materials improvements over the years, and they have the current "Clearspan" spacers to keep the membrane away from the stators, and for tuning purposes. Also I'm sure the conductive strips will be an improvement as well.
Replacing the panels is easy. Lay the speakers on their back, tap the side trim/retaining rails towards the top, gently! Then unhook the panel's electrical connections. It may be necessary to remove the electronics for that purpose. Then reassemble and you're done! While you've got it apart, make sure the foam seals are still good; they'll be under the panels and the woofer grille.

 

[max_dvdt]

I've ordered replacements...

So I called up ML and spoke to Jeff in Service.

I gave him my serial number and I looked at the nameplate again: it appears mine are original Sequels, made 87/11 very very old...

The new panels seemed the way to go at this point so they will be here Monday and I'll let you know how it goes. $560ish including shipping.

They also had some "wee" clips to stop the bass cover from falling down...

Thank you for your support!

K

nominally these are SL3 panels but made for retrofit to the Sequels...

 

[Tube60]

I gave him my serial number and I looked at the nameplate again: it appears mine are original Sequels, made 87/11 very very old...

The original Sequels have no bi-amping option and are easy to tell since there's only one pair of speaker jacks on the back. If the panels have not been replaced before, be careful since the panels were hard-wired to the main board. Just clip the original lead wires, and add some good quality connectors. I like to use Sermos Power Pole connectors; the contacts are silver plated and spring-loaded, and they're set up so that several can be connected together. Good electronics stores should have them. Even with the new panels, make sure the solder joints on the stators are good. My Sequels had new panels supplied with them, and one of them had a cold joint. The replacement panels were purchased in '89 so no warranty!
I'd love to hear how the new panels sound on yours. One of mine are getting noisier and noisier, and no amount of vacuuming and cleaning is helping. I believe the new ones are about 2db more sensitive too. Oh, and of course, leave the speakers unplugged overnight before you work on them.

 

[amey01]

Replacing those panels is the best way to go - you'll have no idea how good they'll sound when done!

 

[enilsen]

"enilsen"'s suggestion of the plant sprayer did the trick.. so my issue is contact oxidation on the film layer...

Call me "stupid" but ML is offering new films for $550 for a pair.. what is involved in replacing the films and are the new films any better with respect to oxidization?

K

Well you could also try fixing the failing hv bias strip by applying a small amount of "TERSASEPTIC" liquid soap diluted with water. This will restore the conductive connection needed here to make them work on a more permanent basis.