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Suggestion to upgrade MMG Crossovers

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Posted on August 16, 2015 at 10:17:03
sferraro963
Audiophile

Posts: 13
Location: Western New York
Joined: April 16, 2015
I've been doing some searching and research on upgrading the crossovers in my MMG's and it has left me more confused than when I started. Looking for some guidance from people who have had good results in tackling this upgrade. I am presently building some stands ala Peter Gunn's design. Should I just email him to ask if he'd kindly share his X-over design or go another route. I was also looking at the MMG tweeks Tazsmonn biamp schematic. I have the amps for it but many don't think you need to biamp. Pretty sure I don't want to go the active route because of the cost for a good electronic crossover. I am not an electronic engineer but can solder read a schematic and have basic electrical knowledge and have successfully built a number of audio kits but try not to be overly technical in your responses. Any input would greatly be appreciated.

 

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RE: Suggestion to upgrade MMG Crossovers, posted on August 16, 2015 at 13:09:07
dumpingground
Audiophile

Posts: 255
Joined: February 23, 2011
I don't have MMG's but I have been actively tweaking my 1.6QR's for years. I have tried upgrading the speaker level crossovers with better components, active line level crossovers/biamp via a minidsp, and finally a passive line level crossover/biamp (PLLXO). The PLLXO by far was the best and also the cheapest.

There are design challenges for a PLLXO, the design will be specfic for the impedance of your preamp and power amps. but well worth the effort.

see here (for the 1.6QR speakers):
http://db.audioasylum.com/mhtml/m.html?forum=mug&n=196102&

 

RE: Suggestion to upgrade MMG Crossovers, posted on August 16, 2015 at 13:19:48
neolith
Audiophile

Posts: 4841
Location: Virginia
Joined: February 21, 2002
Contributor
  Since:
December 2, 2004
PG will gladly provide you with his schematic and also suggest the components. Remember his crossover is a serial design and has different parameters than the OEM. It will sound different than the Magnepan design. It is up to you to decide if it sounds better or not.
If you can solder and follow a schematic then you can easily build an active DIY using PCB modules from Rod Elliott. The modules can be readily adapted from a 4th order L-R to a 2nd order LP and 1st order HP to match the OEM with simple jumpers and omissions. Cost of the PCB, power supply and components will probably be in the $100 range.
As far as the Tazmon model, I have no idea why anyone would want a capless design since inductors are the least ideal of the passive components.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Suggestion to upgrade MMG Crossovers, posted on August 17, 2015 at 11:11:50
sferraro963
Audiophile

Posts: 13
Location: Western New York
Joined: April 16, 2015
Just to make sure you are talking this board. Project 09 - Linkwitz-Riley Crossover. Sounds like a good option. Have you personally used one ?

 

RE: Active Crossover Fear., posted on August 17, 2015 at 14:08:24
BigguyinATL
Manufacturer

Posts: 3475
Joined: April 10, 2002
So for MMG's you have to think about your investment.
(1) Drive them with an a"Audiophile" Amplifier and use the standard crossover. Advantage: no pain no trouble - retain audiophile credibility Disadvantage: Always worried if your a getting the best sound.
MMG's are the best value and do all the "Right" audio reproduction thing (frequency balance (mostly) - great imaging b/c of dipole and line source design minimzed nasty first reflections.
The weakness in the basic MMG design is [A] the lack of efficiency, [B] a bass bump at 55-60Hz (maybe not that noticeable in some rooms), and a little too bright (a matter of taste and where they are pointed)
$600 a pair! Amazing.
(2) if you want to remove the sock and raise the speaker and like wood working a bit, as I do, making a stand to raise speaker a bit is fine, and you can replace the crossover components to higher quality components while you do that.
(3) I'd hate to spend too much money on an MMG tweek or amplifier(s) unless you really want to "play". Then you jump into active biamping. and if you are going to go there then optimization is our goal, so don't even think about "staying Stock". For about $1000 get a pair of Crown XTI1002 Amplifiers. These have Built in DSP's for Crossover, EQ, Dynamics, Limiting and even Subharmonic Synthesis if you get a third one (or a xti 2002) to drive a pair of subs.!
Advantages: You can play like crazy with optimization. and you get a really clean rear side - no bumpsin the fabric. In fact, I used a single 4-pole Speak-on socket at the rear of my MMG's. Disadvantage: You can play like crazy with optimization: this is not for the faint hearted - and don't even think about it if you are going to tune "by ear" and not by measurement. Guarantee you will screw up. So but a good measurement tool.

So my final setup was 24dB/octave L-R at 850Hz, in phase drivers, I HP to my subs at 6dB/octave @ 100Hz (with a parametric EQ on the earlier mentioned "Bass Bump"). I use Dynamic compression above a 15 Volt threshold on 6dB slope that works out to be about 85dB at 100Hz, so the peak output of the LF panel won't exceed 100dB RMS at lower frequencies. I use to use a little high frequency EQ as well - but now I use a tweeters in, 45 degree toe in arrangement that provides a natural off axis EQ. There is a delay in there too for the tweeters - but I am sticking with the delay calculated from on tweeter axis at 2 meters. Finally - because the amplifier offers memory locations I have a presence eq setting that operated on the HF driver only that give me a 2dB Boost or Dip to aid in image presentation with some recordings. I can also switch over to something that somewhat resembles the original factory crossover.

As I said, Active EQ not for the faint of heart. Oh, and using Crown Amps and Speak-on and cheap ($30) four pole cables to each amplifier completely ruins your audiophile credibility - if that's important to you.

The subs use a 24dB/Octave LP Crossover at 85Hz, and a few mild Parametric EQ notches for room modes. My subs are at the sides of the room.

I set up each speaker crossover (the one around 1kHz) individually at first using a band limited (300-5kHz) pink noise test. Really helps to sort our crossover anomalies.


"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius

 

RE: Suggestion to upgrade MMG Crossovers, posted on August 17, 2015 at 14:41:00
neolith
Audiophile

Posts: 4841
Location: Virginia
Joined: February 21, 2002
Contributor
  Since:
December 2, 2004
Yes, I was referring to the P09 and no I have not used it personally as I have a Marchand XM-44. However, both the Marchand and P09 use a standard Sallen-Key topology with OPA2134A dual op-amps. The power supplies are also very similar. I bought the Marchand over 10 years ago when I was more of a nubie but if I were to do it today I would definitely use Ron Elliott's board especially since Marchand no longer offers kits and the price is more than double of what I paid.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Suggestion to upgrade MMG Crossovers, posted on August 17, 2015 at 16:27:07
PG will gladly offer you advice and his current crossover values.

Although I haven't tried every available option, I had my MMG's modded by PG in 2007. The difference isn't subtle. Whether or not it's your cup of tea you won't know until you try.

BTW, PG has begun using new Jupiter caps in his crossovers and he's raving about the results. He's upgrading my old ones with the new caps as we speak, and they should ship out back to me later this week. I'm looking forward to listening and posting my impressions here.

Best of luck to you.

 

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