Planar Speaker Asylum

Welcome! Need support, you got it. Or share your ideas and experiences.

Return to Planar Speaker Asylum

Planar Speaker Asylum

Replacing capacitors in 2.7 QR

69.115.22.157

Greetings -
A number of months ago I finally acquired a quality pair of the exact Magnepan 2.7 QRs that I've wanted for years. With nominal delamination, I sent them back for a full refurbishment. They are back, and seem to be about broken in now. To make a great thing better, I've ordered a pair of Mye stands. And now I'm curious about making them a bit better still - specially, upgrading the stock caps. Is that possible without a whole new crossover, and fitting the new components in the same internal enclosure as the stock caps?
I've seen the crossover schematic in the Tweaks section. Thank you Bigus for posting! I assume I should be swapping out the capacitors with something better (Auricaps?), but I am truly clueless with electronics. Not bad with a soldering iron. But I have to know what to pull out, and what to replace it with.
Can anyone provide some guidance?
Thanks in advance - Steve
PS - Since I'm new here...
Amp: Aragon 8008, pre: vintage Aragon 24K w/external IPS, subs: REL T-5 pair, phono stage: Musical Surroundings Nova II, TT: Rega RP6 w/Exact II cart, tungsten counterweight, Groovetracer reference subplatter, Lim dual pulley, white belts, and Mapleshade megafoot(s) and nanomounts, CD: Acurus ACD 11, FLAC and digital streaming: Cubox-i 4Pro, with LogitechMediServer and Squeezelite, DAC: Audiquest Dragonfly v1.2 w/Schiit Wyrd, interconnects: Kimber Hero and PBJs, speaker cables: Nordost Blue Heaven

Edits: 05/27/15

Follow Ups:

RE: Replacing capacitors in 2.7 QR - pictureguy 10:34:38 06/10/15 (10)
Sure, better caps.
Even the Clarity level (they make 3 or 4 price points) would help.

BUT, nobody seems to want to address the inductors. The most important inductor is in the bass end of the circuit. It sees the most current. Too much juice thru an iron core will saturate and alter the response. AirCore inductors made from a size or 2 larger wire will NOT have that problem. ever.
Converting to an AIRCORE of as close to the same DC resistance as possible will help. Unfortunately, you've now used up ALL the internal crossover space provided and need to go 'external'.
The other factor is that if you lower the resistance TOO drastically (it can be done) you will also slightly alter the frequency balance of the panel.
Too much is never enough
- RE: Replacing capacitors in 2.7 QR - Satie 21:57:20 06/10/15 (3)
  You should be able to compensate for the drop in R with a different L calculated to compensate to keep the same XO pole but the small difference in overall DC resistance will up the lower freq output slightly and that would not be a bad thing for most maggies, perhaps an improvement for many tastes.
  - RE: Replacing capacitors in 2.7 QR - scolley 07:33:54 06/14/15 (1)
    Pictureguy - thanks for the advice. But I'm afraid this indicates that I'm just out of my depth. I thought I could just replace stock parts with BETTER parts of the same specification. But this sounds like there's more to it than that.
    
    Bummer. I might not have the know-how to pull this off...
    - RE: Replacing capacitors in 2.7 QR - Satie 11:05:05 06/14/15 (0)
      You can choose commercially available values for the inductor to come close to what you need with the bigger gauge and lower DC R.
      
      Find the commercial inductor of the original value in the new heavier gauge and take its R spec as Rnew_inductor
      
      A sufficient approximation can be had with R1 = Roriginal_inductor + Rdriver
      
      and R2 = Rnew_inductor + Rdriver
      
      You want to preserve f_c = R / (2PiL) so R1/L1=R2/L2
      
      Solve for L2 and use that value to find a close .inductor (or combo of two inductors to place in series) among standard values.
      
      Recalculate L2 with the actual Rnew_inductor to make sure you are close enough with your selection.
      
      This is an approximation, for precise specs you should run it on Spice but it is not likely to give a significant enough difference to end in you buying a different standard value inductor.
      
      The difference should be around 10% and the increase in low freq output relative to before should be about 0.8db which is subtle but audible. Definitely nothing you would want to fix if you thought the speaker could use some more bass or warmth.
  - RE: Replacing capacitors in 2.7 QR - pictureguy 08:05:15 06/11/15 (0)
    I used a different technique based on my goal.
    Using an online calculator and only standard PVC dimensions for the core, I did several itterations until I saw which way the numbers evolved.
    I than zero'd in on my goal which was to duplicate within 5% the DCR of the issued inductor using heavier wire than stock and having the same number of turns per layer as layers.
    
    My best effort used about 150feet of #14 and had 14 turns per layer and 14 layers.
    The core was 2.22" PVC which is the outside diameter of SOMETHING PVC. DCR was 0.37ohms and just outside my goal. But not THAT far.
    
    This does the following: Doesn't mess with any frequencies. Maintains balance of drivers. Increases power handling. NO chance of saturation limiting.
    
    Too much is never enough
- RE: Replacing capacitors in 2.7 QR - scolley 13:54:09 06/10/15 (5)
  Thanks for the help! It's funny you bring up inductors. Because I was reading about the importance of the bass inductor this morning. I was thinking that the biggest problem in trying to stay internal is likely that inductor. So - as far as I can tell - any good copper foil is out, just because laying on their side they are still too thick. But it looks like Solen Perfect Lay and Hepta-litz air cored may be a bit thinner. But their dimensions seem to be a bit cryptic. A 2.4 mH Solen Hepta is 22 x 45 x 89mm. Not sure what the first two numbers are, and assume 89 is the diameter. But is the height 22 or 45 mm? I'd like to think 22 would fit.
  
  But honestly, it all gets down to the size (length, width, and depth) of the internal crossover space. And I'm not taking my speaker apart just to find out. Anyone know?
  - RE: Replacing capacitors in 2.7 QR - JBen 14:34:40 06/10/15 (4)
    The ERSE Super Q line of inductors at PE surprised me years ago. At a time when most folks were claiming definitive superiority for the foils, I tried these in a couple of values that I also had in foils. Well, it may be a Maggies thing but even after accounting for their lower ESR, the ERSE Super Q took the crown. (Though not for long...ah, but you don't want to go there : - ))
    - RE: Replacing capacitors in 2.7 QR - pictureguy 16:46:21 06/10/15 (3)
      Do NOT be tempted by simply low DCR of the coil. You will change the balance of 'power' between sections of the panel.
      
      I have designs for a coil for the MG1.6 which has a DCR within 5% of stock while being made of heavier wire AND is aircore. I use standard PVC pipe as the dimension and winding bobbin for these coils. Stock coil was 0.40ohms and my plan was 0.38ohms and going from 16ga of the Maggie part to 14ga for my design.
      
      For the 3.5mh coil I needed, I planned for about 130feet of wire per.
      
      NONE of the coils commericall available are 'ideal dimension', either. The coil, regardless of outer and inner diameter should have the SAME number of layers as turns per layer. This makes the coil square in cross section and therefore most efficient.
      Too much is never enough
      - RE: Replacing capacitors in 2.7 QR - JBen 17:26:05 06/10/15 (2)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by pictureguy on June 10, 2015 at 16:46:21
        
        LOL, Pix, Scolley won't even go into a line-level xover to avoid complications for now. If you now get him into building his own inductors he'll have so much fun that we may still make a full-fledged tweaker out of him!
        
        Either that or we spook him away forever. : - ))
        
        RE: Replacing capacitors in 2.7 QR - scolley 07:30:08 06/14/15 (0)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by JBen on June 10, 2015 at 17:26:05
        
        Wow! Building my own inductors? I'm not "afraid" of that - per se. I've built my own multicolor, dimable LED lights for my reef tank because what I wanted was not available commercially. Same situation here. But as with the LED, I had to do a LOT of learning to know what I was doing. And I don't feel like doing that now.
        
        With all due respect to pictureguy's suggestion, I suspect replacement inductors may not be "ideal" - as opposed to building the perfect replacement. But they must be "good enough", 'cuz a heck of a lot of people appear to be doing it.
        
        At least now I understand that the 2 dimension numbers includes an inner and outer diameter. :-)
        
        RE: Replacing capacitors in 2.7 QR - pictureguy 17:33:12 06/10/15 (0)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by JBen on June 10, 2015 at 17:26:05
        
        It's not a hobby, it's a career
        Too much is never enough
RE: Replacing capacitors in 2.7 QR - Satie 02:31:49 05/28/15 (17)
Obbligato gold are generally a good value,

Mundorf MCap Supreme and the doubly expensive silver in oil are about as good as you can get without going to $1000 a pair caps for XOs

Consider using stacks of Dayton foil caps for the high pass capacitors in the tweeter filter.
- RE: Replacing capacitors in 2.7 QR - scolley 07:45:18 06/14/15 (1)
  Satie - what's the point behind using Dayton foils just for the tweeter? I'm not clear on why - if these are suitable as replacements - they would not be used through out the XO.
  
  Thanks.
  - RE: Replacing capacitors in 2.7 QR - Satie 09:20:26 06/14/15 (0)
    Foil caps are normally much more expensive than MKPs so you use them in the most beneficial spots at the lower values. The lowest value caps are the tweeter high pass caps.
    
    There is no reason other than relative cost and size not to use a foil cap at lower freq crossover points. I would not criticize you for using Dayton foils for the large values at the bass/mid XO, but go calculate how many of them you need for the value required and think of how much effort you will need to put it together.
- RE: Replacing capacitors in 2.7 QR - scolley 07:48:05 05/28/15 (14)
  Thanks Satie.
  
  I've not pulled the cloth off the 2.7s to see how much room is in the frame for electronics. But the frame itself is only 40mm thick. So that implies some serious limits on the size of any component. Obviously they will have to be something less than 40mm thick (depending on the depth of the crossover cutout) or they will be poking the back cloth out. And that makes the Mundorf MCap Supremes too thick.
  
  Stacking is a great suggestion though. Thank you. I looked it up, and it sounds simple - wire the caps up in parallel, voltage remains the same, but add the capacitance. Cool. That means a pair of 30mm thick Obligato Premium gold 10 microfarad caps might work for the tweeter (@ 20 microfarads).
  
  I looked for Dayton foil, but cannot find anything except for caps with really low capacitance, all less than 1 microfarad.
  
  Technically, if the Obligatos fit, they could be used for the midrange too (also 20 microfarad). But the Obligatos are 630V. The tweeter caps need 400V, so that seems reasonable. But the midrange is 100V, the Obligatos - at 630V - seem like overkill for that.
  
  Any other suggestions for good caps? Particularly if they are not very large...
  
  Thanks for the help!
  - RE: Replacing capacitors in 2.7 QR - Satie 09:14:06 05/28/15 (13)
    The Daytons are only fractional uF so you would have to build them up as Apogee and Infinity used to do.
    The idea should be to allow you to use the components that sound best at a given budget and that would be best served by an external XO box. There is little space for a higher grade 3 way XO in the panel proper.
    The higher voltage rated caps usually sound better probably because of more uniform film in the thicker (higher voltage) dielectric.
    
    Edits: 05/28/15
    - RE: Replacing capacitors in 2.7 QR - scolley 10:03:11 05/28/15 (12)
      Thanks for the clarification Satie. The idea of building up a lot of low capacitance, but high value, caps makes sense. But - as you say - clearly that's not going into the panel.
      
      But you make a strong point for not avoiding the Obbligato's for the midrange just because of the higher voltage rating. Thanks.
      
      Having looked now at EVERY cap at Parts Connection, I'm beginning to get the idea that my original assumption was incorrect. Specifically - in my ignorance - I assumed that Magnepan put lower cost caps in the speaker, and with a reasonable investment (a few hundred bucks) and a little work I could improve that. But from what I'm seeing, all of the quality caps appear to be larger than what would likely fit in the speaker. Bummer.
      
      And I'm fairly hesitant to take the moulding and cloth off just to start playing the "Let's see what I can squeeze in this hole" game. But it's starting to look like it's either that, or plan on going external. Rats.
      
      Thanks for the advice and help. :-)
      - RE: Replacing capacitors in 2.7 QR - scolley 07:48:01 06/09/15 (11)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by scolley on May 28, 2015 at 10:03:11
        
        OK. I'm clear on the fact that I cannot replace stock 2.7 XO components in the same physical space that the stock is installed - it's going to require an external XO. Fine. So I emailed Peter Gunn.
        
        He was VERY helpful in providing his crossover diagrams with a lot of good, helpful advice. Thank you Peter. But I don't want to bother him any more. So I'll put forward a few questions here...
        
        PG's 2.7 XO calls for two 6.8 uF Obbligato film oil caps, and one additional 6 uF cap. But the Obbligato film oils (oil cans) are SO cheap, I'm assuming it makes sense to upgrade these to Obbligato Gold. Would that be correct?
        
        And to fill the 6 uF capacitor need PG directed me to pick either 5 uF Auricap with a 1 uF Clarity PX or a single 6 uF Jupiter copper cap. And he was kind enough to suggest that without wood frame and everything else to pull the very best out of my 2.7's, the very expensive Jupiters will likely be overkill. I'm good with that.
        
        But PG also mentions on his website that Auricaps and Claritys are as cheap as he's willing to go. So surely there are good caps inbetween the quality of an Auricap/Clarity combo and Jupiters. Like Mundorf M-Cap Supremes?
        
        Am also unclear about PG's reccomendation on a 1.5 ohm Duelund resistor. Would that be the Duelund Standard or CAST?
        
        Thanks in advance for the help. :-)
        
        RE: Replacing capacitors in 2.7 QR - Satie 11:01:52 06/09/15 (10)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by scolley on June 09, 2015 at 07:48:01
        
        Obbligato Gold are a good value
        
        Mcap Supremes (or with oil) are sometimes a good value when on sale. The resistor can also be a Mills.
        
        If you are willing to assemble a large bunch of low value caps then the Dayton foil caps at 0.47 max can be combined to get close to your 6uF tweeter HP at a decent cost and not too much assembly work.
        
        RE: Replacing capacitors in 2.7 QR - scolley 12:19:54 06/09/15 (9)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by Satie on June 09, 2015 at 11:01:52
        
        Thanks Satie. I'm comfortable with the overall cost of the M-Cap Supremes plus the Obbligato Golds. At that price point, it's not the overall cost I'm concerned about, it's whether they work well together sonically.
        
        Clearly there is some kind of voodoo to mixing capacitors that I do not understand. And I'm sure PG has a sound that he achieves with his suggested mix. I don't want to mess that up by looking at higher rated capacitors than what he suggested.
        
        RE: Replacing capacitors in 2.7 QR - JBen 13:45:42 06/09/15 (8)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by scolley on June 09, 2015 at 12:19:54
        
        Hi Steve. Good to see that you are gearing up for some nice tweaking fun with your 2.7s. I must say, Satie's pointers are still valid. You may want to consider that a particular "sound" -- whomever it may be from -- may still need tweaking to your be your own preference. In this sense, these pieces of advise may help you later on.
        
        I do cringe a little when I think that all that money in new parts will not deliver top performance from you Maggies, simply a different, and hopefully more likable, sound. The day you want to maximize the Maggies, a few bucks in parts plus extra power amps can do so, and cost about the same or even much less. Such are the virtues of line-level crossovers. Keep them in mind, or ask around.
        
        RE: Replacing capacitors in 2.7 QR - scolley 14:19:25 06/09/15 (7)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by JBen on June 09, 2015 at 13:45:42
        
        Thanks for chiming in JBen. I'll look into line level crossovers... but a new amp (or amps) is one of those things that is not going to have a high spouse approval factor, I'm afraid. So for now I'm stuck with new boxes of circuits behind the speakers. Thanks for the suggestion though.
        
        IMO "top performance" is an illusive thing. And without serious upgrades to my amplification, pre-amplification and room acoustics, I'm never going to see it. And that's not in the cards at present. Which make small, incremental improvements the order of the day. Which is why I'm looking at a "good but not cost is not object" XO upgrade.
        
        I've never heard a Gunn'ed maggie. But I know people rave about them. And that cannot be happening if PG does not have a good ear for a well designed crossover for maggies. So I'm very much inclined to trust his selection of components for the 2.7 crossovers (that he sells). Which is why I'm interested in learning if the substitutions I mentioned earlier would be detrimental to the PG "sound".
        
        Also, I did not mention previously and important little twist...
        
        The stock XO for 2.7s treats all three drivers separately. PG's XO does not. He straps the mid and tweeter together as a single driver. So it's a simpler crossover, But he appears to be mixing caps to get some sonic affect. And it's that that I'm hessitant to mess with.
        
        RE: Replacing capacitors in 2.7 QR - JBen 15:35:24 06/09/15 (6)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by scolley on June 09, 2015 at 14:19:25
        
        I read you, Steve...my wife hits hard if I break the rules, LOL! The intent is merely to add options that may help as you concoct your own "next approach".
        
        That said, the prospect of you paying so much money for xover parts which -- now that you remind us -- don't even cover a 3-way system is a bit intriguing, to say the least. As you look into the whole thing, you may want to challenge us as a group to see what, say, less than 5 Benjamins could bring to the plate with a line-level xover PLUS power amp. (Darn, if I had the time I'd be shooting for 2 Benjamins just for fun! : - ))
        
        RE: Replacing capacitors in 2.7 QR - scolley 18:56:27 06/09/15 (5)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by JBen on June 09, 2015 at 15:35:24
        
        Jbens - I'm with you on the LOL!
        
        Amplifiers. Speakers. Big speaker cable (like my Blue Heavens). Acoustic treatment. These are things the spousal unit sees. We MUST manage those occurrences. ;-)
        
        Interconnects. Cartridges. Little, expensive solid state phono amps. And MAYBE XO's. These are things unseen. No management required.
        
        Call me a coward, but I'm sticking with the unseen. Picking your battles is how you win the war. :-)
        
        So line level is just out. PLUS it's WAY too technical for me. Great concept. But it's got two strikes against it for me. That said, I find myself at an interesting crossroads, as I consider XO upgrade options...
        
        When I look at the cost, I cannot help but look at what I have in these speakers. It cost roughly $900 to have them refurbished by Magnepan (with shipping and buying a box to ship in). Then there's what I paid for them. All that gets way too close to what these things cost brand spanking new. Why would I DO such a thing?
        
        Because - as a decades long maggie lover - I strongly suspect that these are one of the best pair of maggies made. So suddenly paying $$$ to maximize the crossovers does not seem so silly. Sure, if I buy the Jupiters I won't hear the difference over what I could have had less $$, given my current gear/environment. But SOMEDAY - God willing and the creek don't rise - I may have that new amp and room treatments - and I will hear it then! :-) So go whole hog Jupiter now? Maybe. Or...
        
        Endure the pain of creating external XOs, and build it so that critical caps can be swapped out should I find myself in the fortunate position - in the future - of thinking I could hear the difference. But don't even bother now, if I don't think I'm going to hear a significant positive difference now. ;-)
        
        Thus I find myself interested in trying something better than Peter Gunn's lowest possible option, but not in the stratosphere ($$$) of Jupiter use.
        
        Sorry for the long post. But thanks for listening. ;-)
        
        RE: Replacing capacitors in 2.7 QR - Satie 08:22:23 06/10/15 (3)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by scolley on June 09, 2015 at 18:56:27
        
        Like the 1.7 the main plus is that the 2.7 is a foil and wire driver speaker but near the size of the 3 models. So you get a more coherent sound character up and down the the freq spectrum. What is lost is the ribbon's remarkable transient speed detail and extension.
        
        The issue of PG''s secret sauce matching of caps for a particular sound is something only he can provide but you can choose caps by their signatures on standardized listening tests reported on a couple of sites.
        
        This is one
        http://www.laventure.net/tourist/caps.htm#AAA
        
        I can say that the Dayton foils are on par with the rel cap polystyrenes and the new Jupiter copper in wax are near the same level as the Duelund and V cap but cost about half as much. That opinion is derived as I have not that kind of budget for caps.
        
        RE: Replacing capacitors in 2.7 QR - scolley 14:08:28 06/10/15 (0)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by Satie on June 10, 2015 at 08:22:23
        
        Thanks Satie. That's great info. ESPECIALLY that link to the discussion of how caps sound. Thank you!
        
        I'm going to have to spend some time digesting that. Plus a little more time at http://www.humblehomemadehifi.com/Cap.html. All great stuff, and LOTS to learn.
        
        "Special sauce" LOL. Indeed. ;-)
        
        RE: Replacing capacitors in 2.7 QR - JBen 08:55:17 06/10/15 (1)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by Satie on June 10, 2015 at 08:22:23
        
        Satie, yes, the Daytons are mostly good. I tried some variants. This was during the initil months of scoping my MMGs before going to the planned line-level xover, right after I bought them used.
        
        There was one exception. I could never like the "Dayton Audio Precision 1% Metallized Polypropylene Capacitors". Oh, brother, I tried every which way, including tons of break-in time and other types of speakers. Then I gave them to a friend, without telling him. He later jokingly thanked me for "dumping them" on him.
        
        BTW, in those early days, there was a major surprise. Every single Solen (and other) caps removed from old Maggies, including my own, were right on the money as far a value. With mine, at first, I thought something was wrong with my meter. The 6 caps (2x25uF and 4 x 12uF) showed no variance after almost a decade of use by the previous owner.
        
        RE: Replacing capacitors in 2.7 QR - Satie 10:53:51 06/10/15 (0)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by JBen on June 10, 2015 at 08:55:17
        
        Those are cheap and sound like it.
        
        RE: Replacing capacitors in 2.7 QR - JBen 23:33:00 06/09/15 (0)
        
        In Reply to: RE: Replacing capacitors in 2.7 QR posted by scolley on June 09, 2015 at 18:56:27
        
        Coward? Ha ha! Never crossed my mind. Much less when you have the heart to tackle a xover change to begin with. Care to guess what percent of folks would dare do this? 0.00000.... Crap, my calculator just ran out of zeros!
        
        I think it was Green Lantern in another thread just now who said something along the lines that we do our respective tweaks at our own pace, and that's what matters. We enjoy the fruits as we go along playing with our toys; as we may wish, whenever we may.
        
        Of course, we just want you to get the most fun for the buck...and the least nagging from the boss : - ))
        
        Long post? Hell it is almost 3am and I read through it just fine.

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors:

Parts Connexion