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In Reply to: RE: MGIII active crossover? posted by Satie on August 03, 2016 at 18:38:59
Thanks guys. I expect to hear from Phil tomorrow and I'll let you know. I'm also going to take the Mac in tomorrow and have some lamps replaced and give it a checkup. Unfortunately the rebuilding the Maggies part will probably take a month. Damn, stuck with my ADS. LOL
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Follow Ups:
Since you found the effective XO as 500hz according to magnepan then you should set your symmetrical 3rd order there and are likely to get the best results that way.
The other option is to just follow magnepan's biamp directions and just use the XM9 as a low pass filter and use a 1st order line level which simply amounts to a series capacitor calculated according to the mid/tweeter amp input impedance.
Magnepan says that at 500 Hz the low and the mid/highs power usage are nearly the same so that should work out with my amp. I'm not married to that but it does make a point.
I've started disassembling the Maggies. I found lots of threads on repairing the ribbons but not one on actually removing them. I took the screws out and now it looks like I need to unsolder them. Then they just lift out?
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Are you talking about the ribbon proper or the planar drivers?
The ribbon driver screws out and then you disconnect the wires - usually they have tabs. a few report having to desolder. Are you going to repair the ribbon yourself? Do you have magnepan's ribbon kit with the spray on rubber damping tabs?
I'll replace the entire ribbon assembly if needed. This one is soldered. I'm going to test it after I get it out but even then I may just get 2 new ones. The plan is to strip both speakers this weekend and order parts on Monday.
I'm going to refinish the oak trim also so just about everything will be brand new.
One of the issues that led me to biamping is the Mac 7106. It puts out 100 high current watts into 8 ohms or 150 into 4 ohms but if bridged then the speakers must be 8 ohms. By biamping the Maggies I will be applying up to 300 watts to each speaker. I'm not sure what I will do with the other 2 channels.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
"I'm not sure what I will do with the other 2 channels."
Use them to drive a pair of Magnepan DWM bass panels. It's been reported that even 20.7 owners benefit from them and enjoy their addition.
Thanks again guys. The Mac is at the shop. The tech says the MC7106 are nearly bullet proof except for the lamps. He also says that I don't have to use all channels. I can let the 2 sit idle. Thanks for the tip on the Maggie base units but that's another $800. And I have to get good speaker wires still. I'm leaning toward the Supra Rondo 4X4 on ebay. Made in Sweden, 4mm which is about 11 gauge and a 4 conductor. I don't know about the ends, bare wire or what?
Getting back to the Marchand....I would really like to use it, I have $225 into it already and I hope it is at least as good as OEM. It is a 4th order design. I have another email to Phil about 3rd order so we'll see.
Before I'm done with this project I will have spent $2500+!
One other thing I would like to pick up is a good CD player. I have an old Philips from the 80s or 90s. I hope to improve the sound of the system a bit there. There is no record player and no records but that's another thread.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
You can also triamp if you have extra amplification channels already. Another forum member and I did lots of experimentation on moving the mid/tweeter XO to first order on the 3a and the 3.3. Most of it offline. Also Neo has worked out how to copy the stock slopes into line level passive once you have moved out the tough portion - which is the 3rd order low pass for the bass to mid/tweeter. That portion has to be active XO.
As I pointed out before, you can biamp using the XM9 with a 3rd order board to do the bass LP with magnepan's recommendation and use a passive high pass (just a capacitor in series with your mid/tweet amp's input) for the midtweeter.
'
I considered tri-amp which makes lots of sense with the 6 channel amp. I read Andy's post on MUG on bi and tri XOs. It seems like I bought the wrong XO with it being 4th order and all. I'll explore the others and the options that were recommended by you and others especially for tri-amping.
But now I have big news.....
I stripped one speaker. The ribbon tweeter was soldered in. I had to buy a soldering iron to get it out. I knew I would need one anyway for this project. BTW I had 2 years of electronics in high school but that was when dinosaurs ruled the earth. Under the ribbon are a s#*tload of staples into the sock, I counted 46 on one side of the cutout times 2 for the other side plus another 50 or so on the bottom. I hammered a small crappy screwdriver with a slightly bent tip under the fabric and staple and popped it up some. I did one side this way then pulled all the staples with the end of my Klein wire strippers and repeated for the other side. First thing I noticed were numerous breaks in the mid wire section. I tested the bass and mid and got an open circuit on each. I couldn't see a break in the bass section although it had those typical corrosion spots that others had written about. The worst were along the outside edge. I took the crappy screwdriver and gently scraped those suspect areas and the 3rd one just broke away. It was hard to tell with the corrosion on top but the wire had totally dissolved. Just for fun I was breaking the mid wire at those bad spots by barely touching it. The ribbon tweeter tested good but I'll probably just replace it so I will have all new speakers.
Except for that mid/high internal crossover which brings us back to tri-amping. It seems that I can get an active 3way crossover that will do what I want for under $300 and will sound better than the OEM passive units? I would like something plug and play. I'll have enough to do just rebuilding the speakers and modifying them for the tri-amp setup.
I took pics of the desockifying and could post them if anyone is interested.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Edits: 08/06/16 08/06/16
Your heart really sinks when you do that exercise and find your drivers are literally crumbling.
Are you doing the driver restoration yourself or sending it off to magnepan?
I ordered the parts from Magnepan today. The tweeters, bass/mid rebuild kit and socks comes to $433 including shipping. The price if they do it is $750 to $1000 per pair including shipping. Because I am now going to tri-amp I thought it wouldn't be feasible for them to do it. I'll have to bipass the internal XO and mount 3 sets of speaker connection terminals on the outside. That'll be fun. I have another thread on AK on this, too.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Why not parallel post references to your AK posts here on the MUG as you go along. I am sure it would be more interesting to folks here,
It is hard finding crossovers for the right price. This outfit has a few:
http://www.audioproz.com/AP.php?Prod=Crossovers
Many are professional and mono but there are a few that might work. Could some of you please take a look and see what you think? I am looking for a 3 way now(3rd order?) because I have decided to tri-amp. I am trying to do this for less than $300.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Edits: 08/08/16
You should start with a biamp project at this point both for budget reasons and since it is where most of the benefit happens. From biamp to triamp the benefit is much smaller.
If the Ashly SC-77 is the 18 db 3rd order version (call them and ask) then that will be your starting point and you can at least use it permanently for the bass low pass. The mid HP would be a 1st order passive filer - just a capacitor in series to the input of the mid amp..
Some of the Furmans are 18db units.
If you are not big into analog, go with the digital option with mini DSP - preferably the HD variant.
The old Dahlquist DQ-LP1 has an active 18dB/octave LP section (along with 6dB passive HP).
I looked at that list of XOs at the link you provided - most of them are not "fit for (your) purpose", IMO.
My recommendation - like others here - is to go for a digital XO. I recently replaced the 3-way analogue active XOs that I'd been using with my IIIas (and then my 'Frankenpans') for 15 years with a miniDSP 10x10Hd. This is more than you want to spend - but you could get stereo 3-way XOs by buying a pair of 2x4 units ($105 each) or, better, the new 2x4 Hd units ($205 each).
I'd happily give you my old analogue active XOs - which are set up for IIIas ... except that they are not 'plug-n-play'! :-(( You would need to get cases, wiring, power transformers etc., to make them work. Whereas with the miniDSP units, all you need to do is learn how to program the miniDSP software on your PC.
Good luck,
Andy
PS: And good luck with the re-wiring - it is not something I would ever contemplate (whereas the electronics side in NP at all!)
Andy, I read your post on MUG about active 3 way so that's why I started down this path. Those miniDSPs are interesting but super techie. I was hoping for easier. LOL. Not ruling them out though.
Satie,I was wondering about the feasibility of putting in a 2way/3way switch on the back so I can have it both ways.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
I called the outfit on the Ashley and Furman. That guy talked a mile a minute and wouldn't let me say anything. He was really pushing me to hire him as an audio consultant and kept saying he would make amp recommendations despite the fact that I told him that I already had the Mac. I don't want to deal with him so that's that. That gear is all XLR anyway so that's just another complication.
Still searching for the decent home unit with RCAs so I can just hook it up and turn it on. The miniDSP just looks complicated but I may have to go there if nothing else comes up.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Don't worry about the RCA inputs. TRS adapters are fairly cheap and XLR adapters cost about double that.
The 2 way 3way switch would not be enough since biamping would have you keep internal components while triamping would not. so would require different paths inside the speaker for each setup. The gain from going from biamp to triamp is less cost effective so I would leave that for a second stage upgrade down the road.
I hear you Satie on the 2 way vs 3 way setup. But dagnabbit I got a 6 channel amp which just tilts the whole argument toward 3 way and with 2 way those extra 2 channels are just wasting away (oh dear). And I need a crossover so it might as well be 3 way. BTW I just got that amp back from the shop and it's close to perfect. And I sold my boat yesterday and there is just a little extra cash.
If you were in my shoes would you go for 3 way?
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Triamping the 3A requires particular crossover alignment. The stock alignment is not reproducible for triamping with a commercial analog crossover. You would need to either rework the XO into one of the simpler schemes that have been worked out for it for passive line level. Or have a flexible crossover such as the XM44 or the First Watt B4, or one similar to AndyR's custom DIY job. The best choice among these for an experienced DIY electronics builder is the kind of XO AndyR built. But with power supplies and box it adds up.
If you go for the triamping with the simplified mid and tweeter passive line level filters then a 3rd order Ashly or Furman piece will provide you with a good bass low pass filter.
If you go for reproducing the mid tweeter XO in the original slopes and elbow frequencies then you would need a real active stage for that since they are 2nd and 3rd order and not textbook slopes. You can get that done with a multichannel 5.1 AV pre processor as Computerman did on this forum. That would provide all the gain channels you need and buffering and individual channel level adjustments. With that basic component you can do any crossover alignment up to 2nd order with passive components.
But the complexity gets really bad. So my suggestion is to wait till you have the budget for a First Watt B4 crossover (it is 2 way) and add the 3rd order commercial piece for bass LP and that would allow you to triamp precisely as you can. But that will definitely blow up your budget.
For the passive 1st order mid tweeter section in passive line level, Davey from the UK has worked out a crossover alignment that can be implemented easily with just the commercial 3rd order for bass LP and passive components.
The DSP crossover option - like minidsp is an order of magnitude more flexible and has room correction options. If you are playing predominantly digital sources then you have nothing to lose using the DSP. if you have the budget then a DEQX unit would be the way to go.
I've just about made the decision on the miniDSP 4x10 for $500. The others are too expensive or not as configurable. I've read about half of the manual. I can use it 2 or 3 way and it seems like it will do all the needed slopes and configurations. I don't have any records or tapes so there is no analog input but it will do both if my gear changes in the future. And it has RCAs. The XLRs were just one more issue and expense on the others. The computer setup on the mini DSP is near the limits of my abilities but I 'll just have to adapt.
Thanks guys.
Bobber
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
Those ribbons were stuck just a bit. I got the one out.
Mac MC7106, Maggie MG111, ADS 810 & 780, Pioneer SC-1522, Carver M.0.5T, Dahlquist 903, Velodyne, Infinity
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