Magnestand MMGs - Crossover Upgrade?

cpalcott · « **on:** 3 Mar 2015, 06:54 pm »

I have a pair of Magnepan/Magnestand MMGs with the original PeterGunn crossover recipe. While the sound of my system has been mostly fantastic for some time now, I do still feel there is an overemphasis of some frequencies in the upper mid range that shows itself in the form of audible distortion on vocals. It almost seems like I am hearing the compression used on the vocal track to make it pop, cut through, and in the process over emphasizing certain resonant frequencies. Like I am hearing the voice resonate the diaphragm of the mic, if that makes sense. Perhaps between 1.5KHz and 4KHz? Could this be a cross over issue? Anyone have any suggestions fro a passive crossover recipe for these speakers?

Davey · « **Reply #1 on:** 3 Mar 2015, 07:09 pm »

You bet it's a crossover issue. The alignment of that crossover is significantly different than stock and bumps up the midrange of the speaker quite a bit. I understand why a lot of folks like the sound because it grabs your attention and really gives the speakers a "presence" quality. However, it ultimately became tiresome for me.

I suggest (as an experiment) to switch back to the stock crossover and listen for a few weeks. Give yourself time to adjust mentally and then ask yourself which is more accurate for a wide variety of music.

Cheers,

Dave.

cpalcott · « **Reply #2 on:** 3 Mar 2015, 07:16 pm »

Thanks for the quick reply, Dave! I have 2 sets of original MMG crossovers, one set from the early mmg years, and one from the 2000s. Should I go vintage or 2000s? Thanks again.

SteveFord · « **Reply #3 on:** 3 Mar 2015, 10:51 pm »

I'm not Dave but try them both.
I had two pairs of MMGs at one time, early and then the second series.
I still have the early ones if that tells you anything.

Davey · « **Reply #4 on:** 4 Mar 2015, 05:05 am »

My crossovers are currently wired with a parallel configuration. 2mH on the woofer and 15uF on the tweeter. I think a resistor of at least 0.5 ohms in series with the tweeter is required....but YMMV depending upon your room conditions. The MMG's are too bright at the top end in any configuration without a series resistor on the tweeter IHMO.

Cheers,

Dave.

cpalcott · « **Reply #5 on:** 6 Mar 2015, 03:36 pm »

So I have had the "original" MMG crossovers on my "2000s" based Magnestand MMGs for a couple of days. Very interesting. The trouble upper midrange frequencies have definitely tamed. Not all together gone, but tamed. Really not a significant difference in terms of presence from the "2000s" crossovers. Bass is a little more loose. Overall vocal and instrument tonality is warmer yet seemingly very accurate. What suprised me most is the increase in subtle low-level micro detail. Translation...I'm really diggin' these old crossovers!

The "originals" are currently still connected to the original backplate with inline fuse and tweeter attenuator ports with a ceramic resistor in place. I am assuming it would be best for the resistor and fuse to go. So I'm thinking I want to build new crossovers for these. This would be my first time "building" a crossover, so any assistance you guys can offer would be greatly appreciated.

Davey...I see you have been using a parallel config with 2mH on the woofer and a 15uF with .5 ohm resistor on the tweeter. Now my Magnestands are setup in the traditional PG style with woofer and tweeter wires exposed to the back. Would the 2mH/15uF combo still be the way to go? Can you recommend what brand to use for these parts. Would you be willing to share any diagrams of how these should be wired? Thanks a million!

Davey · « **Reply #6 on:** 6 Mar 2015, 05:14 pm »

You'd wire them exactly as your current (original) crossovers are wired. You're just substituting a 2mH coil for the 2.2mH coil and a 15uF capacitor for the 12uF capacitor.

http://www.integracoustics.com/MUG/MUG/tweaks/MMG%20XO%20Diag.gif

This is more of a fine-tuning of the original configuration, vice a wholesale change like the Magnestand crossover.
You'll still need a resistor though....IMHO.

Dave.

SteveFord · « **Reply #7 on:** 6 Mar 2015, 09:58 pm »

You mean the resistor in place of the staple(s)? If so, I guess it's what the amp and preamp sound like or maybe how your ears are. I've got a junk drawer full of resistors.

Davey · « **Reply #8 on:** 7 Mar 2015, 01:14 am »

I guess I'm missing some kind of obvious reference here, but what the heck does tweeter attenuation have to do with staples?
You've got a junk drawer full of resistors? I guess I'm missing some kind of context there too.

Dave.

SteveFord · « **Reply #9 on:** 7 Mar 2015, 11:22 pm »

I thought I was clear - are you talking about using the resistors for the tweeter attenuation (as opposed to the big staples)? If so, it's possible that something in your system is the culprit.
What are you using for an amp, preamp and source? That would help to put things in context.
I know that you have your MMGs suspended from ropes from the ceiling but that's about it.

jk@home · « **Reply #10 on:** 8 Mar 2015, 12:16 am »

I get it. Steve is referring to the jumper "staple looking" thing on the tweeter binding posts...not the staples that hold on the socks.

Davey · « **Reply #11 on:** 8 Mar 2015, 01:54 am »

The jumpers are staples? I had no clue.

'Learn something new everyday.

My system has no issues regarding amp/preamp/etc. The tweeter simply needs to be attenuated a bit relative to the woofer. My preferred system would be to bi-amp and in that instance performing relative adjustments is easy. My suggestion with the resistor is for those who are using a high-level crossover with a single amp.

Cheers,

Dave.

SteveFord · « **Reply #12 on:** 8 Mar 2015, 01:09 pm »

The jumpers remind me of industrial strength staples.
I've never cared for the sound with the resistors in place of them but that's just me. Replacing the staples with short lengths of speaker cables didn't really seem to do much one way or the other.
The resistors might have helped when I had the Crown tour amp hooked up to the 1.7s but it didn't occur to me to dig through the junk drawer for a pair.
That amp did work out really well with MMGs and a modified Carver C1 preamp, though.
It's all how you match things up, I suppose, which is why it's helpful when members list their systems.
Enough of the thread hijack.

Davey · « **Reply #13 on:** 8 Mar 2015, 02:50 pm »

Based on my outdoor measurements years back, I estimate the sensitivity of the tweeters to be approximately +1.5db (nominal) higher than the woofers. If a person experiences that in their listening room it doesn't mean there's an issue elsewhere in your system. The tweeter simply has inherently higher sensitivity.

The resistors are the only simple/effective way to equalize that offset.

Cheers,

Dave.

sfox50 · « **Reply #14 on:** 8 Mar 2015, 03:12 pm »

I hope I'm not side tracking the thread, but I have seven year old Magnestand MMGs that had one of the .5 ohm Dueland (sp?) resistors fail after a couple years. I replaced both with Mills 12 watt .5 ohms and I'm happy with them.

cpalcott · « **Reply #15 on:** 8 Mar 2015, 04:30 pm »

Planning to do this crossover upgrade, but after doing a bunch of forum searching, I'm lost in a sea of brand names and types. Anyone have some suggestions on brands/types of inductors/capacitors for this mod. I have late 2000s panels in standard magnestand frames with card facing front, exposed mylar to the back. Running these off an NAD cc390dd integrated (150 watts/side) on the 4ohm setting. Harmonic Technology Melody line speaker cables. My room has plaster walls, hardwood floors, but significantly dampened with curtains, plants, area rugs, soft furniture, etc. Ideas?

Davey · « **Reply #16 on:** 9 Mar 2015, 03:07 pm »

I wouldn't spend a lot of money. The alignment/design of the crossover is much more important than the audiophile "quality" of the components.

Madisound has a nice selection of parts with decent value.

https://www.madisoundspeakerstore.com/solen_perfect_lay_14_awg/
https://www.madisoundspeakerstore.com/solen-capacitors-page-2/

Cheers,

Dave.

cpalcott · « **Reply #17 on:** 10 Mar 2015, 06:43 pm »

So my original crossovers have (2) 12uf capacitors. Should I replace these with (2) 15uf capacitors or just (1)?

Davey · « **Reply #18 on:** 11 Mar 2015, 12:08 am »

Yeah, those are the older crossovers. I would recommend to replace with a single 2.0mH coil and a single 15uF capacitor. Plus a resistor in series with the tweeter for attenuation as you see fit.

Dave.

kappa546 · « **Reply #19 on:** 15 Mar 2015, 08:46 pm »

What happens with the blue cap below the 12uF caps? I will also be upgrading crossovers on mmg's but I really don't know which design to go with. some swear by the SMGa design, there's one design that discusses a capacitor-less tweeter section that sounds interesting... I can't figure out which to go with. Also considering a line-level active crossover.

Andres