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and I can't wake it up. It has been buzzing a bit in the bass channels the last little while, and then a little louder buzzing. I tried swapping balanced to RCA's on the bass panels, still the buzz. The buzzing coincidentally started when I hooked up my new DAC, but I know it is the XO because I get no buzz when it is not in the loop. (Shhh,.... don't tell anyone, but I am running the pre-amp signal full range into the mid/tweeters; <1 watt)
So off to the shop with the Marchand. It is difficult to find quality "authorized" electronic audio repair in this small town; I just went through with this for my Mcintosh amp, I drove it 4 hours to the Vancouver area, and was without it for 3 months, but I think I have found a guy working out of a music shop I will give a go. I believe an electronic crossover is more of a pro-audio unit anyway? and it does not look like a complicated piece of equipment.
Anyone else had an issue similar? any ideas which part might be at fault in this unit? I don't plan on fixing it myself, but just curious. The odd part is that the power light still comes on; so the main fuse appears to be fine.
Follow Ups:
I was relieved to hear the gray-haired fellow who fixed it has been repairing electronics for 40 years. Miltronics is the name of the repair outfit, inside Lee's music store here in Kamloops BC in case someone else should need repair in this area.
He said it was a break (crack) in one of the copper chases in the main power board. Probably caused by heat? he laid down another piece of copper on top of it and soldered it in. No parts replaced; Total cost $45.
In and out in 1 day; Yippee!
Like I said, I competent technician will have no trouble fixing issues like this. :) The XM44 and PS is an extremely simple design.
Heck, it would have cost you more than $45 just to 'ship' the thing to Phil!
Glad you got it working.
Dave.
It should be easy to fix by any competent technician. Marchand has a schematic (sans power supply) in the XM44 manual. The PS is a straightforward bipolar linear supply that easy to troubleshoot.
Dave.
I strongly suggest calling Marchand. You maybe able to pull the PS module yourself and send it to Phil for evaluation and if needed repair or replacement. A new PS is $65.00.
I married the perfect woman. The downside is everything that goes wrong is my fault.
My XM-44 is also asleep and I have no intention to wake it up, unless forced to by some change(s) in my rig.
Assuming Mr. Marchand is still in business, my advice is to phone him and then ship it to him for repair. (In fact I found myself forced to do that several times.) In the event he's no longer in this business, your guess would be as good as mine, if not better.
I have one that I built about 12 years ago but have not used since I got the 3.7i. They are kinda bulletproof.
Since you said bass channel s , it must be something they have in common, mainly the power supply. If it's a 60 or 120 hz noise, you may not hear it in the treble because it is filtered out.
In any case, before you ship, try pulling the boards out and cleaning the contacts with Deoxit.
Phil Marchand is great to work with and he will make it right
Best luck.
I married the perfect woman. The downside is everything that goes wrong is my fault.
I did pull out the modules/filters and reinsert them a few times to improve the contacts. I pulled out a small flathead and checked all the screws inside; all tight.
You guys missed the part about me going to try a local electronic fixit guy who does pro audio gear. I would like to send it to Phil, but I am on the west coast in Canada, and he is on the east coast across the border, and sometimes it is such a time consuming painful exercise and expense to ship; I have had some bad experiences with courier companies. Cross your fingers for me.
By the way, speaking of the modules, I have 280 HZ 24db LP and HP that I have never changed; they have worked fine to my ears. I recall reading years ago that the stock suggestions did not work well. With some recent other changes to my system I might experiment this summer when I have some free time. What other crossover module options have others preferred in their 3.6's?
Symmetric even order xo's really don't cut it with Magnepans. The ideal is to have custom modules that simulate the original crossover, which is a 4th order LP at 280 Hz and 1st order HP at 230 Hz. Since you have the 280 LP already you just need to order two new HP modules. If you can handle a soldering iron you could modify your HP mods yourself. The manual gives you all the diagrams and instructions on what value you need. In short you will need to remove some caps and resistors and insert jumper wires. The resistors will need to be increased in size but you probably will be able to use the caps already on the board. Cost should be about $2.00 for both boards. If you get stuck on the value of the resistor, email me or call Marchand.
I married the perfect woman. The downside is everything that goes wrong is my fault.
Edits: 01/23/17
Took me a while; but here is the thread info I read several years ago. Based on Nils advice I went with the symmetrical 280 and have liked it. Perhaps I will order a few more modules and play around with them as my room has changed, along with a few other goodies.
Posted by Neuro (A) on April 9, 2008 at 19:52:15
I have a biamp setup, and I've been playing with crossover slopes and points for quite some time now. I thought I'd share my observations with fellow Magnepan 3.6 owners.
- 250hz 18dB/oct LP, 200hz 6dB/oct HP (stock recommendation): What was Magnepan thinking? My only guess is that a dyslexic wrote the manual and they really meant 250hz HP and 200hz LP. The overlap results in a "wooly" sound. I'm all for warmth, but I was never happy with the resulting sound. Also, phase coherency really suffered.
- 280hz 24dB/oct LP, 200hz 6dB/oct HP: Hmm, even though this looked close to the curves shown in Davey's response model, this didn't sound right at all. For some reason, putting the woofer and midrange panel in phase here helped some.
- 190hz 24dB/oct LP, 190hz 24dB/oct HP (recommended by Andyr): Now we're getting somewhere! Remember, if you're using a symmetrical fourth order slope, the drivers have to be in phase. Bass and midrange in phase, with tweeter out of phase was better for me. I really loved the sound at first--very clean, very coherent, the soundstage seemed very full without any holes. After time, however, I noticed the signature of each driver.
- 190hz 24dB/oct LP, 200hz 6dB/oct HP: After using this, it seems that the first-order high pass is key to the drivers blending well. There's definitely a gap in the low-midrange though. I used this to tide me over until I got...
- 180hz 18dB/oct LP, 200hz 6dB/oct HP (recommended by Andyr): This seems very tonally balanced, maybe a touch warm in the midrange, but NOTHING like the stock recommendation. Detail is excellent.
Conclusions so far:
I might stick with the last configuration above. After hearing the symmetrical slopes, I do find the asymmetrical crossover's soundstage to be not as solid as it could be. It would be nice to see what a triamped, fully in phase setup would sound like. Alas, that's out of my price range at the moment.
-- Nils
Posted by Neuro (A) on August 10, 2008 at 21:05:48
In Reply to: Observations on crossover point experimentation (MG3.6) posted by Neuro on April 9, 2008 at 19:52:15:
Phil Marchand was kind enough to set me up with a 280hz HP to match the 280hz LP. I never tried it until about a week ago. Needless to say, I am VERY happy!
- 280hz 24dB/oct LP, 280hz 24dB/oct HP: The anemic, lean sound of the 190hz crossover point is gone. Coherency through the crossover point is seamless. Also, I'm hearing lots of detail in recordings I've listened to dozens of times. Timbre is so improved that I wonder how I put up with it before. :) :)
It seems that the bass panel is essential in the ~200-400hz range (which is one reason that the 180hz third-order low-pass works, and is possibly the reason that Magnepan recommends a 250hz 3rd order LP).
When I go 3-way active, I'm going to try 240hz LR4 as well, just for fun. I'll get to experiment all over (but at least I'll be going with LR4 for the other crossover as well).
-- Nils
Obviously you have been doing your homework. The values I gave you are almost identical to the OEM - the 4th order LP is not quite a true L-R filter having a Q of 0.51 rather 0.50. This is really trivial but I can send you the values to get a 0.51 Q if you are that pedantic :).
Magnepan spends some time developing the crossover design and IMO someone would be hard to come up with a better design and that is why I stick as close as I can to the OEM.
From your research you can see there is a considerable variation as to what people think is better and this may have to do with their rooms and ears.
One comment of interest was " 280hz 24dB/oct LP, 200hz 6dB/oct HP: Hmm, even though this looked close to the curves shown in Davey's response model, this didn't sound right at all. For some reason, putting the woofer and midrange panel in phase here helped some." I find this of interest because swapping the polarity of 1st order filter makes absolutely no difference - the absolute phase difference remains the same and I defy anyone, even those who claim to hear absolute phase, to tell the difference.
The point being that a lot of this subjective and what you need to do is find what you like and then just listen to the music and forget about the system.
I married the perfect woman. The downside is everything that goes wrong is my fault.
Edits: 01/24/17
Sometime in the near future I will call Phil and see if he has any notes regarding 3.6 owners preferences, and then I will order a few more modules based on you guys recommendations and experiment again.
Maybe I will post and see if anyone has some used ones kicking around they want to sell first...
Thanks for your input guys.
The suggest biamp XO in the manual is obviously a typo. The 3.5 model gives 3rd order 200hz LP and 2nd at 200hz HP or 1st order at 250hz HP. I think they just swapped the freq. for high and low pass when the 3.6 manual was written.
Spacing the crossover using a 6db HP for the mids is pretty much the "standard" maggie approach.
From the 20.1 manual (corrected for obvious typo)
"Set the high pass section at 200-300 Hz, 6dB per octave. Due to standing
waves at the crossover frequency, the low pass section may require adjustment
from as low as 90Hz (12dB Bessel) to 150Hz (18 dB Butterworth). Typical
settings are in the middle of this range. Optimization of the low pass can be done
by ear (with music) or spectrum analysis"
For the T IVa they suggest LP Butterworth 3 at 250hz
HP 12db at 400 hz.
They also suggest that symmetrical 12 or 3rd order XOs at 250-400 hz would work well.
I have tried many combos on my T IV/Neo8 for both triamp and biamp. The main deal is to get good time alignment. Aside from the XM 44 that I used with Marchand's suggested LR4 modules I also used an Ashly XR 77/18 3rd order and later a Rane LR4 to experiment further as well as various 1st order and 2nd order symmetrical and asymmetrical crossovers.
The LR4 symmetrical did quite well but you could tell that the bass was crude as you passed from playing the violin in the upper strings to its low string. And Cellos changed character going from one end of the range to the other. B3 was better in that regard, but 1st order was magic. With the drivers time aligned in an arc, imaging was perfect.
I then went on to switch the setup to the short wall and try my hand at wall loading. After much frustration trying the 1st order again just without managing an equidistant setup with the bass panels face forwards to max out wall loading, I swapped to the classic maggie 3rd LP and 1st order HP, just that I lowered the HP to below the midrange driver's acoustic rolloff and let the Neo8 do as much as they can and filled in
with the bass at B3. If you go up with the LP to the -3db acoustic HP point of the mids at about 250-275hz and fix time alignment then you have a full if not slightly ripe tonal balance but lose clarity as the bass panels are audibly losing detail and take over output in the 200-250hz range. Lowering the LP down to below 200hz lightens the tonal balance and makes it a bit lean to the benefit of clarity and imaging. Time alignment is adjusted to compensate for group delay differences between the LP freq) In that circumstance it is a bit better to raise the bass level somewhat to compensate for the leaner subjective balance, particularly if you take the LP down to 150-160hz.
Biamping with LR4 loses you phase info at the mids and damages imaging and tonal texture. It may not be that bad with the 3.x models but with 3 of them I cooperated on the 6db HP was pretty much necessary to make the most of the midrange, anything else squished the soundstage and made the images lose palpability. The main thing is to carefully tune the B3 LP to match with the 6 db HP. It wasn't very practical to do that with the Marchand but once I had things dialed in I redid the boards and it was fabulous, just that it is more so with only a cap rather than the whole Marchand gain structure. So I ended up selling it.
nt
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