From Tazsmonn
Please write me on which numbers you want.
I'm sending this text as you requested. Please write me any comments, questions or thoughts you have on these.
As always. YOU are solely responsible on how you choose to use this information and you will void the warranty doing any mod to your MMG's. This information is accurate to the best of my knowledge. If things go wrong don't come crying to me !
I have done 2 and 3. Many have done 2. I found #3 with 50w L-Pads in-between the amp and speaker to give the best performance, this was without a active crossover and included the use of the panel subwoofer.
I'm now going to try to tell you how the MMG's are put together, please refer to drawing #1.
The original crossover is a rather good design, but as it is there is room for improvement and we'll be getting to that. The neat thing is that you'll know quite a lot before even touching them.
The tweeter is crossed over at 1.7 Khz by 2 paralleled 12 uF capacitors on the + side. The fuse is on the - side. I'm going to guess that the brown wire is the = side of this panel and the brown is - . Most people upgrade tis capacitor, I propose a even better sounding mod in #3 for the tweeter panel.
The mid/woofer panel is crossed over at 1.2 Khz ( .707 x tweeter crossover frequency ) This gives a very smooth crossover to the treble. This is a 12 db peroctive crossover circuit. The inductor is .75 mH and the capacitor is 25 uF. (like we couldn't just read the label)
For the faint hearted whom only want to up grade parts these are my suggestions. Replace the treble panel cap with a "better one". Use the former tweeter capacitor for the mid woofer panel, the difference of 1 uF here makes no difference. ( I'm not sending the mathematical proof !) Also this will be better than the one there now, however using anything else would be a waste of money. Replace the coil with a .75 mH 18 or lower gauge air core coil. I finally replaced mine with an air core coil and was very worth it, better sonics over the stock iron core coil. ( Did this about 3.11.00)
You could also try drawing #3.1 . ( created 2.12.00 while rewriting this ) You still swap capacitors but for the tweeter you add a resistor, parallel coil to form the high pass filter. For you that have never heard a capacitor less tweeter you are in for a big surprise. My motto is why up grade a capacitor when you can design it out of the circuit. As you can see the signal will only flow through a resistor then straight to the tweeter panel. Start with 4 ohms, you can get this by paralleling 2 Radio Shack 8 ohm non inductive resistors and believe it or not these are very neutral sounding resistors.
Biamping Mods
See drawing #2.
In this mod you simply disconnect the one end of the tweeter capacitor and solder it to the fuse holder as shown and parallel the fuse with a 50 ohm 10w resister also available at Radio Shack. The 50 ohm resister is there in case you should blow a fuse. The amp still has a load connected to it and the power to the tweeter is reduced by a factor of 12 saving it from harm. The resistor is shorted out by the fuse and has no sonic effect. If the fuse blew and the resistor was not there the amp would blow too.
For all the biamp circuits with crossovers you can improve the performance by adding 50w L-pads in-between the amp and the speakers. It adds more depth and gives you the option of level matching. Plus you can passively biamp and still be loading the amp across the entire frequency range which gives a smoother sound.
#3 is the biampable version of #3.1
As of 2.8.00 I've been doing this mod with the L-Pads and have found it to be perhaps the pinnacle of the MMG's performance with the Subwoofer panel, as a triamped single ended tube system.
#4 This one is for use with a 6 db peroctive active crossover. Which is why you can remove all capacitors and have to switch the mid/bass panels wiring to correct the polarity.
#5 Similar to #4 But for use with 12 db low pass, 6 db high pass active filter.
That's about it. Please write me on how it goes and here's some other TID BITS from the web and me.
Replace steel U-clips with copper cable and gold banana clips.
>From Martin Leach
Replace the jacks with gold ones... as above.
Don't bother with jacks at all. Solder speaker cable directly to the crossover, bypass the use of U-clip. See drawings.
Stands 3 foot ???? watch this spot.
2 foot, have standing vertically, very popular and my favourite.
Subwoofer is a must if you want serious bass. See panel sub woofer info.