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Old 31st December 2011, 12:22 AM   #1
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Default Another Sequel II Mod

See post below.
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Power Mac G5 running 10.5.8 > Musical Fidelity V-Link > Tact Mini 2.2 > Tact S2150 > Modified Martin Logan Sequel IIs
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Old 31st December 2011, 08:12 PM   #2
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Default Removal of Output Resistor Mod on ML Sequel II

After studying the schematic for the Sequel II, Tyu mentioned to me that unlike other Logans, the Sequel has a couple of resistors that sit between the transformer and the panel, and that they might not be needed. The resistors are located on the bottom side of the crossover board on the side nearest the bias board. One resistor parallels the panel and the other one is in series, in an L-Pad arrangement. Here you can see the gold-colored parallel resistor below the board, the other series resistor was to the left of it, but has already been removed:

Click the image to open in full size.

I found I could do all the soldering on both resistors without taking the board out. To remove the gold-colored parallel resistor from the circuit you only need to disconnect one side. The black resistor in series must be removed and a jumper wire put in its place. Here you can see the red jumper wire placed on the top of the crossover board toward the bottom of the picture:

Click the image to open in full size.

I did only one speaker to compare to the other. The difference was significant. The speaker without the mod, when directly compared to the modded speaker, had a very noticeable distortion as if a separate modulated sound was riding above the primary note. The difference in clarity of the sound was striking. In addition, as my son says, for the first time the MLs sound dynamic and have "jump".

The problem was they sounded brighter. I tried fixing the balance with the equalizer in iTunes, but could not get it right. Out of necessity and like most of us, I have my MLs too close to the back wall (about 2 feet). I also noticed that if I listened in the extreme near field the speakers sounded good. So, as a last resort, I put two sheepskin rugs hanging behind draped over the panels. That was it! By far the best I have ever heard the speakers. It was as if the added energy going into the back wave now overpowered the front wave and needed to be absorbed. The rear absorption also improved the imaging and made far-field listening sound similar to near-field listening (before listening in the far field was far inferior). After hearing the speakers this way, I will never go back to running them fully open in the back.
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Power Mac G5 running 10.5.8 > Musical Fidelity V-Link > Tact Mini 2.2 > Tact S2150 > Modified Martin Logan Sequel IIs

Last edited by Rob in Montana; 31st December 2011 at 08:16 PM. Reason: clean up
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Old 4th January 2012, 02:27 PM   #3
tyu is offline tyu  United States
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Rob
Thanks for your time...
As for the back wave be louder....this may be the interface tranfourmer being wired out of phase with the woffer.....but if the Sequel have a gap at the top...were you can see the panel only.... may get some help buy just blocking this opening
an then there is a small back brase....adding just a littel more brase...like a 2" peace of tape....i use panter paper tape...you seenthe blue...just block the panel top...an add one strip it the brase....i have found this can be used to tune the panels..on all the logans...or any ESL.....small changes across the top of the panel has a BIG afact on the output.
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Old 5th January 2012, 06:59 PM   #4
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Default Attenuating the Back Wave

Hello Tyu. You can see my new thread on how I decided to attenuate the back wave using a thin solid baffle and polyester damping:

[IMG]Click the image to open in full size.[/IMG]

RE: the transformer wired out of phase. Do you find the Martin Logans sound better with the speaker wires for the LF and HF attached out of phase? I noticed that Stereophile grappled with this when they tested the Sequel IIs.
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Power Mac G5 running 10.5.8 > Musical Fidelity V-Link > Tact Mini 2.2 > Tact S2150 > Modified Martin Logan Sequel IIs
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Old 6th January 2012, 01:07 PM   #5
tyu is offline tyu  United States
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Rob all the logans now have the LF drivers an the panels in phase......if an when you do the tranfourmer mod in the other post....the back of the panels get the grond...neg from amp...the front is then driven from the front only where the only mylar coting is.. this help on the ...tiptup top end.. If i can over to your house an put the back board out of my SL3 or Ascent....your an all these are the same...you base driver an panel drive tranfourmer are a little diff...the Ascent crossover can an i would put it in the sequel... i did this to more than one pr Of sl3 an thay sounded better....I have 4 pr of logasns here now that i am doing the Tranfourmer mod on....an finding some weard ness in the crossovers.....more later..
thanks for your time
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Old 7th January 2012, 04:55 AM   #6
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Tyu, sorry, which transformer mod? I thought I installed all the mods you were suggesting, except for the one about pulling the panel apart and driving from both sides.
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Power Mac G5 running 10.5.8 > Musical Fidelity V-Link > Tact Mini 2.2 > Tact S2150 > Modified Martin Logan Sequel IIs
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Old 7th January 2012, 01:40 PM   #7
tyu is offline tyu  United States
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This post has pic......

Geting better output of the ESL panel....
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