Martin Logan reQuest Crossovers

[wrf 5,268]

My quest to sample as many speakers as possible has finally lead me to a pair of Martin Logan's.  I've always been fascinated by electrostatic speakers and it was time.  A pair of reQuest speakers popped up on craigslist a while back.  Retail was around $4500 in the late '90s.  The owner said the panels were shot, and he was letting them go fairly cheap.  In talking with him and with Martin Logan I came to question his diagnosis of bad panels.

 

He assured me the crossovers were OK.  In fact, he had removed them and sent them back to ML.  They had tested them and given them a clean bill of health.  He had the documentation and the response curves from ML to prove it.  Only problem was that if the panels were bad, it would take $2K to get new ones.

 

I went over to take a look.  They were immaculate.  He was sure the panels were bad so the price was really, really low.  I bought them.

 

I got them home, set them up and they didn't sound too bad.  The panels sounded fine to my ears, but the bass was dramatically missing.  I got to thinking.  He had the crossovers out, so maybe he screwed up the wiring on the woofers.  I opened each one up and checked the phasing on the woofer wiring.  Sure enough, one was hooked up backwards.  Eureka!!

 

I put them back together and they sound great.  Great imaging.  Great balance and now Great bass.

 

Sometimes you get lucky...

 

Here are some photos for the curious.  First one is the crossover and high voltage power supply.  Second one is the schematic.

 

 

 

 

 

 

 

 

 

[aslan7 955]

Wow.

 

Great find and an even greater story Wayne!

 

Congrats!

[wrf 5,268]

Almost forgot.  Here's a photo of the speakers.

 

Actually they aren't really lying on their sides.  Seems that the photo uploader has a mind of its own.  It's right side up prior to uploading.

 

Maybe the site remodeling can fix that. 

 

 

[morjet 30]

Good looking set of speakers! That ghostly imaging always gets me.

[4krow 7,443]

  Great Wayne. I have almost the same story with a set of JBL speakers that used an electronic crossover. Yup it was set up wrong. Best deal I ever got.

[jazzman53 1,280]

Great save there, Wayne,

 

Sounds like there's nothing wrong with the panels either.   BTW, the panels can be rebuilt (new diaphragms) for a couple of hundred bucks in materials, should they ever need it.

 

What I never learned how to do was design a passive crossover for an ESL.  All of the crossover design calculators I've seen are for conventional speakers and are useless for ESL's because of their frequency dependent impedance. 

 

Hybrid ESL's are fairly easy to make work if using an active crossover and bi-amping but it takes a lot of smarts and a fair amount of trial and error to to build a passive one that sounds right.  I have no idea how to do it. 

 

 

 

 

 

[4krow 7,443]

 I also made an attempt with digital, line level crossovers. Wow, don't even go there. Turns out, I like the sound of a well designed passive anyway.

[Chops 694]

Those reQuest's are the newer, bigger brother of my SL3's. They're great sounding speakers, aren't they?!

[jazzman53 1,280]

 I also made an attempt with digital, line level crossovers. Wow, don't even go there. Turns out, I like the sound of a well designed passive anyway.

 

Wish you could hear mine! 

To each his own of course.   Even though I would not use a passive setup in my personal speakers, I do regret being unable to show a passive design on my DIY ESL website so that more people could afford to build them.  

 

The ML passive crossover also includes components to EQ the panel for dipole rolloff and a characteristic response peak from the transformer (somewhere around 3K I suspect) .   So if you were to bi-amp the speaker without also EQ'ing the panel it might well sound thin in the mid bass and tinny on the top end.    

[wrf 5,268]

 

 

Sounds like there's nothing wrong with the panels either.   BTW, the panels can be rebuilt (new diaphragms) for a couple of hundred bucks in materials, should they ever need it.

 

 

What sorts for problems would I listen for if the panels do have problems.  I understand that the ML panels do degrade over time, but I'm not sure what the symptoms would be.

 

If it comes to it, I would certainly be interested in taking a shot at rebuilding them.  ML claims it's not cost effective (for them).  Their quote of $2K is for brand new panels, sized as direct replacements for the reQuests.

 

 

[4RUNNER 524]

my smaller aerius II sound good but one panel requires more power to drive it to the same volume.

[jazzman53 1,280]

 

 

 

Sounds like there's nothing wrong with the panels either.   BTW, the panels can be rebuilt (new diaphragms) for a couple of hundred bucks in materials, should they ever need it.

 

 

What sorts for problems would I listen for if the panels do have problems.  I understand that the ML panels do degrade over time, but I'm not sure what the symptoms would be.

 

If it comes to it, I would certainly be interested in taking a shot at rebuilding them.  ML claims it's not cost effective (for them).  Their quote of $2K is for brand new panels, sized as direct replacements for the reQuests.

 

 

- A buzzing would indicate a loose diaphragm

- Low output could be the bias supply but most likely would be either a bad connection where the wire from the bias supply contacts the diaphragm or a deteriorated conductive coating on the diaphragm itself.  A bad contact is easily cured with coating the contact area with a conductive paint (like used to fix a broken deicing grid trace on an automobile back glass)-- IF you can dismantle the panel without destroying the diaphragm.   A deteriorated diaphragm coating is easily fixed too-- but only IF you can get the panel apart without destroying the diaphragm.  Some ML models do not bond the front spars to the diaphragm and some do-- the ones that don't can be disassembled without destroying the diaphragm.  The diaphragm can be recoated with 1 just wet coat of Licron Crystal ESD (about $50).   Replacing the diaphragm is more complicated but do-able at home.  Diaphragm material (Mylar) is available on Ebay.   

 

You can verify the diaphragm coating by temporarily coating it with a wipe on coating of 1/2 water 1/2 dish washing liquid.  If the coating was the issue, re-coating with the dish soap would restore full volume.  

[AndrewJohn 10,968]

Very nice deal.  Great to have unexpected outcomes.

 

I'm nostalgic about your listening room, there, Wayne.  I had my first Carver setup (2 TFM35's) in my garage in Marin, when I lived in that perfect-weather state.  Carpet on the floor, and the cars outside.  Lots of stuff for diffused surfaces on the walls, too.  Many a cold beer and tunes there in the 80s and 90s.    (needed a "weeping" emoticon...)

[wrf 5,268]

Very nice deal.  Great to have unexpected outcomes.

 

I'm nostalgic about your listening room, there, Wayne.  I had my first Carver setup (2 TFM35's) in my garage in Marin, when I lived in that perfect-weather state.  Carpet on the floor, and the cars outside.  Lots of stuff for diffused surfaces on the walls, too.  Many a cold beer and tunes there in the 80s and 90s.    (needed a "weeping" emoticon...)

 

I used to have my "Transient" system set up in a guest room.  The wife didn't like all the wires.  We recently sold a car and now there is space in the garage.

 

The neighbors haven't yet offered an opinion. 

[PMAT 2,061]

Is that your BAT pre out there with your 1.0t?

[wrf 5,268]

The one in the photo is a VK-31. The good one is inside with my main system.

[loner_t 2,571]

 

 

 

Actually they aren't really lying on their sides.  Seems that the photo uploader has a mind of its own.  It's right side up prior to uploading.

 

Maybe the site remodeling can fix that. 

 

Z is reading this thread. He will usually correct the EXIF data and re-upload the image with proper orientation.  

[zumbini 6,153]

Heck of a deal Wayne, and an easy fix too. ENJOY THE MUSIC!

 

...Actually they aren't really lying on their sides.  Seems that the photo uploader has a mind of its own.  It's right side up prior to uploading.

 

Maybe the site remodeling can fix that. 

 

 

 

 

As I've noted previously, most digital photos include EXIF data that includes the orientation of the camera.

EXIF compatible programs read the EXIF orientation tag and automatically rotate the image view to match.

Unfortunately Cute Editor (the forum's image editor) does not recognize/support EXIF orientation tags.

As a result a photo taken with the camera/phone in portrait mode is displayed in landscape mode.

 

To fix it I downloaded your image, opened it in IrfanView, removed the EXIF tag, and saved the edited photo.

Here's the edited image which now displays properly: 

 

[wrf 5,268]

Thanks. Now I can go back to the garage and listen some more without laying on my side......

[PDR 1,195]

[Ar9Jim 6,520]

Congrats on a great score Wayne .. There's a youtube video.. I couldn't post the link.. It's inside the Martin Logan plant..

 

Youtube search- electrostatic speakers, How its made.. Pretty amazing. 

 

 

 

 

[chiroacademy 852]

Anyone interested in a pair of Martin Logan Aerius? I would love to sell, pick up, no shipping.

[AndrewJohn 10,968]

Thanks. Now I can go back to the garage and listen some more without laying on my side......

 

They look bigger too, when they are vertical..., Giants!