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Old 05-31-2014, 08:33 AM   #81
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

You're very welcome, i'm real glad you finally managed to revive the bugger
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Old 06-02-2014, 07:32 AM   #82
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

I was just thinking. I don't know if they will see this, so much time having elapsed in between, but I would like to express appreciation to LuigiDJ whose quadruple bypass surgery inspired my own. I would also like to thank Momaka for his input.

I also didn't mention that, in the process, I acquired another pair of these monitors for 99. These haven't blown yet, but inspection shows the process is under way. So I am going to do elective surgery on them as per Khron666's plan - relocate the startup cap on each next to the UC3844's and move the small cap under the board.

It would seem to make sense to me that anyone with a pair of these speakers should check the placement of these components and move them if they have the old "bad design" layout. That would cost nothing and the speakers could then last three or four times as long. There must be hundreds of thousands of them out there...
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Old 06-02-2014, 03:02 PM   #83
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Amen to that - as i might've mentioned earlier on this thread, i'm on my 2nd pair of these I'm just the tiniest bit miffed that some folks over in UK are at times unwilling to mail stuff like speakers, abroad; but every now and again one comes across some who do
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Old 06-02-2014, 03:22 PM   #84
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

that's because speakers are big & heavy and the u.k. has some of the most expensive postal service in the world.

and it's only getting worse now it's been privatised and the shareholders want to see some cash!
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Old 06-02-2014, 05:37 PM   #85
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Well yeah, but i'm still the one who would be paying for it, so... I'm afraid that argument's a bit moot / void
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Old 06-03-2014, 04:32 AM   #86
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

What happened to your first pair?
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Old 06-03-2014, 10:36 AM   #87
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

A friend (amateur singer) bought'em off me, along with an AKG Perception 200 (that i also "revived"), with the intention of starting his own mini-project studio No horror-stories here, i'm afraid
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Old 06-03-2014, 12:01 PM   #88
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

I am just busy doing the elective surgery. Wondering why I can't just swap C8 and C14, provided I get the polarity right on C8. Is there any threat to the little ceramic from the two big resistors?

Btw, I have already tried it and of course it works fine. The circuit diagram says it will. Just wondering about the heat. I have the resistors bent away from the ceramic and of course away from the large caps.
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Old 06-03-2014, 12:15 PM   #89
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers



Okay - so this is what the final layout looks like now after pre-emptive surgery. The underside of the board doesn't look any different.
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Old 06-03-2014, 12:17 PM   #90
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Well, the idea with the ceramic is thatit has way lower impedance at higher frequencies than the electrolytic, and that's one of the reasons it's best if it's as close to the Vcc pin of the chip, as possible.

Don't quite me on this, but i'm reaonably sure it's got to do with the relationship between the capacity and the ESL (equivalent series inductance). I've seen plots in film cap datasheets, looks a bit like a rounded-off V or Y, with the minimum at the resonance frequency for the particular cap.
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Old 06-03-2014, 12:21 PM   #91
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

What will I notice different about the sound? Or is it to do with longevity? Heat issues? It seems to work fine. As far as the technical things you said above, I have no idea what that means. I am but a lowly musician.
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Old 06-03-2014, 12:24 PM   #92
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

More like, if you move it 2 miles up the road, that ceramic cap will do precisely shyte Keep it as close to the chip as you can There's plenty of room on the underside of the chip, and no high-voltages to worry about...
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Old 06-03-2014, 12:27 PM   #93
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Aha. Thank you. Loss of elegance there.
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Old 06-03-2014, 12:35 PM   #94
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

I've always been much more of a function-over-form kinda guy Besides, the electronics are on the inside anyway, who cares if/how elegant they are or aren't? If it works...
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Old 06-03-2014, 04:17 PM   #95
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Mr Khron666 sir...I believe I was referring to your very own quotation of elegance? An "elegant solution" I believe it was...partly emulated by my far less able self. A tribute perhaps?
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Old 06-03-2014, 06:22 PM   #96
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Flattery will get you nowhere And there's no point in playing yourself down, especially after you made it THIS far with this project
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Old 06-04-2014, 01:36 PM   #97
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Well, I am feeling good about it all. It was a huge learning curve. Not having a background in electronics I am pretty chuffed.

My original two monitors are either side of my production desk. They are my dedicated recording monitors and are connected to my Soundblaster Elite Pro (old I know but still an amazing card/breakout box). They work 100% now and as you know sound awesome.

The second pair is above them and slightly wider apart, tilted downwards. They are hooked as the main speakers into a 7:1 Yamaha DSP A1092 surround system. I have this system hooked to my non-production PC. I use this to test my mixes in various configurations. This sounds totally phenomenal.

I like a very wide range of music from prog to jazz to R&B to acoustic/country, techno/trance and more. This arrangement is heaven for me.

So this whole exercise has been really worth it.

Now I have a whole bunch of components for repairing these monitors left over. As you know, you need one you have to order a thousand.

So I am wondering whether to acquire a third pair that needs fixing as a backup...or to sell a few "Alesis repair kits" and save some folks some money...
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Old 06-04-2014, 01:46 PM   #98
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Uuu, someone's ambitious Sounds like quite a setup you've got there, though.

"When i grow up", i'm planning on getting a couple more pairs of speakers made / done / etc. But before that, i'll have some DSP design to tackle And several hundreds of euros to blow on custom enclosures
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Old 08-07-2014, 12:02 PM   #99
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Quick update: All four speakers still working 100% and sounding awesome! Can't stop thinking about acquiring another two to fix. Lol. Don't know what I would do with them...spares?
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Old 08-08-2014, 06:01 AM   #100
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Default Re: Repairing Alesis M1 Active mk2 Monitor Speakers

Expand the 7.1 system?
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