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Picked up my pair of 3.6's locally last year, thinking that I'd eventually try to bi-amp using my (25 year) old Marchand XM9 crossovers, not really sure how I'd go about it.Before bi-amping, I did the HpW mod (external mid high-pass-ribbon bypass) with highly positive results. After a LOT of researching old posts on PA, and finding a tremendous amount of information, I went with using the active fourth-order Marchand on the bass panel and a PLLXO on the top (REL RTE polystyrene capacitors on the mid/high amp input)-not the standard arrangement with which I likely would have gone without external guidance. All I can say is that the results are remarkable-much better clarity, resolution, and authority in the bass. More importantly, all the glare and shrillness that had me considering selling these things is gone, gone, gone. So just wanted to thank everyone in the past who posted their experiences on this board, I couldn't have done it without you. Special kudos to Davey and Neolith.
Right now, money being tight, I'm using my secondary system's Musical Fidelity A3.5 integrated's power amp section (240W/4 ohms) as the second amp, but hope to acquire a Parasound A21 before too long.Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
Edits: 05/02/15 05/03/15Follow Ups:
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The Relcap is sweet and to my ears sounds as good as more expensive Teflon caps. The 3.6 fits right into your setup -- the OEM bass LP filter is essentially a 4th order LR (perfect for the XM-9) and the mid HP is a 1st order which is perfect for a line-level passive filter. Congratulations.
At the same time as ordering the RELs, I got some of the inexpensive silver Rohm polystyrenes. May try them just for the heck of it, but don't really expect them to be an improvement upon the RELs. DID get a couple of the RELs from PartsConX that were off spec by a factor of 8. Will need to send them back this week. The ones currently in use measure fine, as do the Rohms.
Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
I like the REL polyStyrenes and found them better than the Sonicap Teflons (Platinum)
Best value I found are the Dayton brand foil caps from Parts Express. The value range is very limited but the price is phenomenal considering the sonic quality you get. I think they are near the REL PS caps in SQ.
What is your LP filter elbow freq. on the XM9?
Hi Satie- right now it's 260 Hz. I tried 280 just for entertainment value, but things sounded too "thick", not unexpectedly. Will likely get resistors for 250 (stock) and 240, just to play around. The XM9 also has a crossover region damping adjustment and various settings of that makes a noticeable difference, too.
Certainly there's some experimentation to do. All in all, though, I'm tickled pink with how good these things sound now.
Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
MWE:
I have a pair of 3.5R's and have been toying with biamping them for a while. I am a very visual person, can you post some detailed photos of the changes you made? I have been lurking on this forum for a number of years now and somewhat understand what modifications you performed, but not enough to charge down the path without many incorrect assumptions. I enjoyed reading your success and it sounds within reach for my system.
Thank you in advance,
Tom
The Marchand XM-9 crossover that MWE used creates symmetrical (same roll-off rate and 4th-order) high/low pass slopes. (It's not easily modifiable to alter this aspect.)Neither the stock outboard box or the Magnepan recommended bi-amping crossover slopes are symmetrical. What MWE did is create an asymmetrical electrical crossover by not using the high-pass outputs of his XM-9 crossover and creating a first-order passive "bypass" section around the Marchand XM-9 to drive the mid/tweet amplifier. The gist is that he's created an active bi-amping scheme but very close to the Magnepan-designed slopes for the 3.6 speaker.
Since you're a visual guy, take a look at the design I posted many years ago here on the forum. Or take a look at Neolith's spreadsheet which shows the electrical slopes for all of the Magnepan speakers.
http://www.integracoustics.com/MUG/MUG/tweaks/davey/mg3.6xo.htm
Hope that helps.
Dave.
Edits: 05/04/15 05/04/15
nt.
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
Nothing is done to the speakers themself, except removing the outbord passive crossover.
The 3.5 is not as easy to convert as the 3.6.
The 3.6 need an active low pass crossover, the first order high pass cut-off can be done at the input of the power amp feeding the mid/tweeter section, it is just a capacitor.
The 3.5 need an active low pass and a second order high pass cut-off. Is not that easy to do that with a passive solution at line level.
He can still implement a 4th order active LP and 1st order HP combo like MWE has as the speaker drivers are not that different. Given a choice rather than using an active XO that was there anyways, I would have used a 3rd order 1st order combo.
your rationale for 3rd order LP for the 3.6. XM9 boards are only $70, (easily doable) and could be ordered as 3rd order; I know Magnepan rec's 3rd but the stock passive is 4th and wonder if it would be worthwhile trying the 3rd. Any illumination would be appreciated.
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
If you go that way be prepared for trying out a wide variety of values for both the mid HP and bass LP in the 3rd +1 XOs.
If you like what you are getting then stick with it and save yourself some trouble. The main thing is to have the mid HP filter be a high quality cap and have separate amps doing high power bass duties and refined performance for the mid/tweeter. So long as you already have the HP and LP matched you will not see that much improvement - if any.
If you are designing from scratch then yes, the 3rd _ 1st is what I would do first.
nt.
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
Thank you all for the information
My intent was not to highjack the thread. Many apologies.
a Marchand XM44 will do what you need. They're $1K and nice units. Marchand used to offer kits but no longer, alas.
Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
Used it for a decade
Do you still use the original internal crossover?
Yes, still using that. At this point, I'm not really interested in tearing into the innards to tri-amp. Went through all of that upgrading my 1.6's stock XO (before having them "Gunn'ed) and just don't want to deal with it . The current improvement is SO good that it's just not, for me, worth the hassle of dis-assembly and sock removal and all that jazz.
Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
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