Hello - Sequel II Owner

[theaudioman]

Hello all forum members. Long time Martin Logan owner but new to the forum. I have a set of Sequel II's.

 

[JonFo]

Welcome to our little corner of the Internet.

Also have Sequels I bought new in '93, currently my rears. have you updated panels on them yet?

 

[theaudioman]

Hi I bought mine used in 2004 and they had just had the panels and woofers replaced so were basically brand new. They came with the old panels so I'm using one as a center channel - thought about building another set to use as rears too but ML wouldn't sell me parts. Said they were too old. I just happened to come across a power supply/crossover last week on Reverb dot com so I bought it and hooked up a panel to test. Now I need to build it out as a center channel.

 

[im18font]

Hi I bought mine used in 2004 and they had just had the panels and woofers replaced so were basically brand new. They came with the old panels so I'm using one as a center channel - thought about building another set to use as rears too but ML wouldn't sell me parts. Said they were too old. I just happened to come across a power supply/crossover last week on Reverb dot com so I bought it and hooked up a panel to test. Now I need to build it out as a center channel.

I replaced my panels on my SQii's as well, how did you repurpose your panels? Thanks ahead of time.

 

[theaudioman]

I replaced my panels on my SQii's as well, how did you repurpose your panels? Thanks ahead of time.

Hi - I have a friend that has 3d printed a mount for me. I still need to build a box to work with the mount and buy a woofer. Pictures coming soon.

 

[Brandon Hartwick]

I've heard of other people on the DIY Audio forums turning old ML panels into center channels, I think that's a fantastic idea. At some point I might try this, it would sound wild for gaming I'm sure.

 

[theaudioman]

Prototype mount that's able to swivel up and down a bit. I still need to build a box for the woofer and buy a woofer. I'm thinking I'll place this on top of the woofer box and permanently mount it somehow.

 

[Brandon Hartwick]

Prototype mount that's able to swivel up and down a bit. I still need to build a box for the woofer and buy a woofer. I'm thinking I'll place this on top of the woofer box and permanently mount it somehow.

This is very cool and it's giving me all kinds of ideas

have you thought about maybe putting something behind the panel to help with some of that back wave? Also, how will you be doing the crossover?

 

[theaudioman]

This is very cool and it's giving me all kinds of ideas

have you thought about maybe putting something behind the panel to help with some of that back wave? Also, how will you be doing the crossover?

Glad it's helping with the brainstorm. My buddy came up with the idea and had a 3d printer so I can't take any of the credit. I have definitely thought about enclosing the back somehow to deal with the back wave. Just haven't looked that much in to it yet. I'm open to ideas on that though as that seems like it could be a problem spot.

 

[JonFo]

I have definitely thought about enclosing the back somehow to deal with the back wave. Just haven't looked that much in to it yet. I'm open to ideas on that though as that seems like it could be a problem spot.

You definitely want to enclose the back of the panel, so as to mitigate both the comb-filtering of reflected sound coming back through the membrane, as well as eliminate the dipole cancelation down low (well, low for the panel, ~250Hz).
A layered absorption sandwich should do it, just keep checking with measurements that it is absorbing enough to reduce the comb-filtering.

 

[Robert D]

You definitely want to enclose the back of the panel, so as to mitigate both the comb-filtering of reflected sound coming back through the membrane, as well as eliminate the dipole cancelation down low (well, low for the panel, ~250Hz).
A layered absorption sandwich should do it, just keep checking with measurements that it is absorbing enough to reduce the comb-filtering.

I wonder, why didn't Martin Logan make their early center channel speakers ,like the theater, closed back?

 

[JonFo]

I wonder, why didn't Martin Logan make their early center channel speakers ,like the theater, closed back?

A couple of reasons, one being market forces, customers expect an electrostatic to be 'open'. The other is R&D, not enough proof that closed is better for a center.

For instance, their first center, the Logos (which I owned), had the woofer in a box placed inches behind the panel. With only a slim layer of foam to absorb the rear wave, that thing had horrible comb-filtering and (in retrospect) poor overall performance.

Their next models went fully open (except for the Motif), so now it's on the user to figure out placement and treatments to mitigate the comb-filtering and dipole cancelation.

With the ESL C, they went full monopole and it performed quite well given its small size. The market did not barf all over the fact it's a monolopole, as by then many of us had been harping on the benefits of monopoles for centers. Since It worked well, it sold well.

Then the C18 came out and they nailed it.

 

[JonFo]

To get an idea regarding how to mitigate the rear wave, take a peek at the interior of the ESL C.
We see the cavity between the ESL elements and the box totally stuffed with what looks to be foam.
Same for the back of the woofer throat, where they use two layers of folded foam

 

[theaudioman]

Great feeback @JonFo. Now I have to decide what woofer(s) to pair up with my center channel. I think I'm going to build the woofer box behind the panel to not only deal with the back wave but to house the woofer(s). Since it's only a center channel I don't plan to pair up a 10" woofer but I'm thinking more along the size of a 6.5" or dual 6.5". I also have a mini-dsp 2x4 so I can get creative with x-over and EQ.

 

[JonFo]

Since it's only a center channel I don't plan to pair up a 10" woofer but I'm thinking more along the size of a 6.5" or dual 6.5".

Don't underestimate the amount of woofage a center needs, so I'd suggest 2x 6.5".
My center runs with 6x 7" woofers + the same sized panel you have, and I find it does nicely. But then I wanted crazy headroom to hit my goal of 105dB spl at low distortion.

 

[theaudioman]

6 woofers looks awesome too! I'm trying to keep it as simple as possible. I think 2x 6.5" will look good and handle my needs.