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In Reply to: RE: Replacing capacitors in 2.7 QR posted by scolley on May 27, 2015 at 07:04:27
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
Follow Ups:
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.
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...
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.
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
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?
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 : - ))
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
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. : - ))
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. :-)
It's not a hobby, it's a career
Too much is never enough
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