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MG 3a's vs MG 3.6

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I have an old pair of MG3a's (as well as 2b's). My impression of the 3a's (which I have owned for over 15 yrs)is that they must be played fairly loud to "open up", have a slightly bright treble (despite a resistor in place) and have a somewhat recessed (not forward) midrange. I have had these speakers connected to more amps and preamps over the years than I could list. The speakers have been in many rooms as I have moved several times in the past 20 years. They sound consistent from room to room as all rooms have been large. My basic ? is:
How much as the Maggie product evolved in the last 15 years? How much difference would I hear comparing a 15yr old MG3a to a much more recent MG 3.6? Would the difference be subtle or striking?
Lastly does anyone know the lower crossover point in the MG3a's? (between bass and mid)

I thank those who take the time to reply.

Follow Ups:

Re: MG 3a's vs MG 3.6 - bobwire 07:47:07 10/27/03 (1)
The problem with any of the 3xx series of Maggies is that there is a hole in the midrange caused by the crossover. The crossover uses both 12dB and 18dB slopes. The mid to tweeter does not match because the mid is tuned to 1300hz while the tweeter comes on at 2Kz! Also the slopes are not max-flat. They droop to much. As I have said in these pages I re-tuned my maggies so the mids go up to 2K and every slope is max-flat. With these changes your Maggies will disappear. Look for the changes at
http://www.integracoustics.com/MUG/MUG/tweaks/bobwire/
- Re: MG 3a's vs MG 3.6 - pburke 13:41:34 10/28/03 (0)
  does this hole in the midrange have anything to do with what this tweak accomplishes (raises midrange 1.5db)?
  Peter
  - http://www.hpw-works.com/maggie/mag3-6-mod.htm (Open in New Window)
Re: MG 3a's vs MG 3.6 - andyr 04:12:31 10/27/03 (4)
Hi jcw,
I've had my IIIas for almost as long as you, although I've only listened to them in the same 27' x 17' room all the time.
However, at one stage I did have a pair of 3.3Rs to compare against my Maggies (which had their crossovers upgraded with Solo coils and Solen/Infini caps).
My understanding is that, really, there are minor differences between the IIIas, the 3.3Rs and the 3.5Rs. Particularly if you compare a stock standard 3.5R with some IIIas which have had their (crap) stock crossovers upgraded.
However, the 3.6 is a big step forward as it has a push-pull magnet arrangement? Is this right, you 3.6 owners? Even so, the same condition applies - you can make them sound much better (and much, much better than IIIas) by doing the same component replacements!
Re. the Maggie IIIa base/mid-panel crossover points:
* the base LP slope is 18dB
* the mid HP slope is 12dB
* the manual says the base LP crossover (-3dB) point is 300Hz
* the manual says the mid HP crossover (-3dB) point is 500Hz.
However, I've modelled the Maggie IIIa crossover values and the graph gave the following -3dB points:
* base LP -3dB point: 290Hz (near enough!)
* mid HP -3dB point: 740Hz!
I suspect this 'gap' would explain the recessed mid-range which you hear. In other words, if you redo your crossovers (or replace passive crossovers with active), you should change the component values to lower the mid HP -3dB point to, say, 400Hz.
Regards,
Andy
- Re: MG 3a's vs MG 3.6 - monk1 09:16:17 10/27/03 (2)
  The MG-20.1, Tympani-1D used push-pull drivers but not the MG-3.6.
  - Re: MG 3a's vs MG 3.6 - Green Lantern 09:49:19 10/27/03 (1)
    anyone know if Apogee's used P/P in any of their models? What advantage does this design have? thanks
    
    ____________ _// ________________
    back to the music - GL
    - Apogee didn't have P-P - lwang 21:19:48 10/27/03 (0)
      But they did utilize a true ribbon midrange on some of their model.
      P-P introduces a linear magnetic field so that when the driver move in and out of the resting position, it would not encounter field of different strength, which would cause different force to be excurted on the driver than what the signal demands.
- The only push-pull maggie config is the 20.1 (n/t) - joeb 08:37:03 10/27/03 (0)
  n/t
Bass- Mid X0 = Low pass is 18db @ 300hz, high pass 12 db @ 500 <nt> - neolith 16:43:21 10/26/03 (0)
Re: MG 3a's vs MG 3.6 - akino 08:19:01 10/26/03 (15)
While not having the same amount of time with my MGIIIa's as you, (only had mine for 6 months)I agree completely with your characterizations. I have actually compared the IIIa's to the 3.6's and feel the 3.6's have a more "forward" midrange and slightly less bass with the highs being almost identical. I've compared them side by side in the exact same room using the exact same electronics (lucky to be able to do this). The difference to me was subtle which is why I chose to buy a used pair of IIIa's. I actually preferred the IIIa's (I felt they were stronger in the lower end). I plan to change the crossover components internally, and to bi-amp to circumvent the small shortcomings of the midrange and to smooth out the highs a bit more.
Cheers,
Andy
- Re: MG 3a's vs MG 3.6 - andyr 04:16:22 10/27/03 (14)
  Hi, Andy,
  Why don't you jump straight to 3-way active on your Maggie IIIas. Yes, it's expensive in terms of amps but you can also spend a heap of money on 'audiophile grade' passive coils and caps!
  I'm certainly not sorry I went active.
  Regards,
  Andy
  - Re: MG 3a's vs MG 3.6 - pburke 10:06:10 10/28/03 (0)
    I'm considering active bi-amping my 3.5R's, but after some research, I think the costs are not even close to building a passive XO with "audiophile coils and caps"
    For 3.5R's in my setup, I'd be looking at about $800 for a complete crossover transplant (inside and external) plus silver rewire, terminal posts, etc)
    The active crossover would cost me about $500 in parts, and a second pair of Odyssey Mono Extreme amps goes for $2650
    Since I would want to redo the internal wiring and crossover anyway for this active bi-amp setup, I'm definitely going with the $800 option first. I can always pull the low/midrange X/O and go active, losing maybe $500 in the process, but since I don't have $3500 to do the rewire, internal X/O, active X/O and second pair of amps, I know I'll go passive first.
    Peter
  - Re: MG 3a's vs MG 3.6 - akino 07:31:49 10/27/03 (12)
    Holy Moly!
    I havent even considered doing 3 amps! Dont know why...
    I think I will. Are you using a sub? Did you just yank all the passive crossovers??
    What a great thought, Hmmmmmm...
    Thanks,
    Andy
    - Re: MG 3a's vs MG 3.6 - andyr 11:57:47 10/27/03 (11)
      Hi, Andy,
      Yes, I just yanked all the passive crossover.
      I'm thinking about adding subs but that would be some serious money and I wonder - with the base I'm already getting - whether it would be worth it!
      If you use the AKSA amp kits that I've gone to, I think you'll find the amp cost for going active is not excessive (www.aksaonline.com).
      Regards,
      Andy
      - Re: MG 3a's vs MG 3.6 - akino 12:15:25 10/27/03 (10)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by andyr on October 27, 2003 at 11:57:47:
        
        Hey Andy, Thanks for the info.
        I allready have two amps. Both Phase Linear. All I need is one more. I could do that no prob. My research mainly would involve active crossovers. What are you using?
        I see most are 2way if you use them in stereo mode, but if you want 3 way, its mono and requires two actives. I've seen the Rane so far. What are you using for active crossover? Do you like it?
        Andy
        PS...Great Name ;> )
        
        Re: MG 3a's vs MG 3.6 - andyr 12:48:48 10/27/03 (9)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by akino on October 27, 2003 at 12:15:25:
        
        Hi, Andy,
        I use Rod Elliott's active - he sells you the crossover PCB for about US$25, and a power supply PCB, and you then buy the parts he lists (go see @ www.au.sound.com).
        They are L-R phase coherent crossovers, with either 24dB or 12dB slopes ... as you say, if you want 3-way stereo, ya need to buy 2 boards.
        I started off with the usual 24dB slope setup but I am just in the middle of building a replacement pair which have the same slopes as the passive IIIa crossover - ie. 12dB everywhere except for the base LP which is 18dB.
        And, yes, I think they make my Maggies sound terrific ... as do audionut mates who come and listen!
        Regards,
        Andy
        
        Re: MG 3a's vs MG 3.6 - akino 13:03:28 10/27/03 (8)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by andyr on October 27, 2003 at 12:48:48:
        
        Awesome!
        I think I'm going to go for this. What crossover freq's are you using? (see above messages) Apparently their is a "hole" in the stock midrange crossover??
        Cheers!
        Andy
        
        Re: MG 3a's vs MG 3.6 - andyr 13:48:15 10/27/03 (7)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by akino on October 27, 2003 at 13:03:28:
        
        Andy,
        Yes, if you follow the posts, one says the bottom end of the mid-panel band pass should be extended downwards (because there's a hole between it and the base LP) ... and another says it should be extended upwards (because there's a hole between it and the ribbon HP!).
        What I have found, by modelling the crossover, is that the base driver gets a much higher signal level (from its crossover section) than the mid panel and the ribbon. This is just the way it comes out, when you put the coils and caps specified into the program, but it leads me to wonder whether this was done because the base driver is less efficient than the others. IE. in an active setup, you should copy this.
        With the passive setup, though, you are stuck wtth the relative sound levels - except for the ribbon attenuating resistor. One advantage with an active setup is that you can adjust the output level for each driver (by means of a potentiometer), so you can tweak the sound balance to come out how you like it ... or to compensate for the Maggies being too close to the corners of the room etc..
        With 24dB slopes, I suggest you have quite a choice of what frequencies to use, because the L-R setup is designed to sum flat over the crossover range ... ie. by design there are no 'holes'.
        For mine, I used 325Hz and 1,720Hz but I think next time around I would take the upper one to 2,000Hz.
        In my new setup, I am trying to mimic the passive crossover (as near as you can using standard component values). Because of the mix of 12dB slopes and 18dB it is hard to say what the actual -3dB or -6dB points are but the slopes 'cross over' each other at 420Hz and 2,700Hz.
        Regards,
        Andy
        PS: if you've any more Qs, perhaps you should email me directly at:
        andy.redwood@telstra.com
        
        Re: MG 3a's vs MG 3.6 - sailor 10:23:41 10/28/03 (1)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by andyr on October 27, 2003 at 13:48:15:
        
        Ok guys here is the reason for the IIIa's strange crossover points and slopes. First the bass panel, (no crossover), is good out to about 6000 HZ. but it has a +6db shelf starting around 1300 HZ to about 5500 HZ. So to counteract this, the panel must be rolled off early and steep. Although electronically the slope is 18 db, the spl slope is far more gental. The suck out around 400 HZ is because the bass and midrange are out of phase at that point.
        
        Re: MG 3a's vs MG 3.6 - andyr 14:38:59 10/28/03 (0)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by sailor on October 28, 2003 at 10:23:41:
        
        Hi Sailor,
        Thanks for the explanation. Could U answer one thing, though:
        * U said "The suck out around 400 HZ is because the bass and midrange are out of phase at that point."
        So why wouldn't one simply reverse the base driver wires to get the two in phase? What result would this have?
        Regards,
        Andy
        
        Re: MG 3a's vs MG 3.6 - pburke 10:20:58 10/28/03 (4)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by andyr on October 27, 2003 at 13:48:15:
        
        "you can adjust the output level for each driver (by means of a potentiometer)"
        i'd avoid puytting a potentionmeter in the signal path. The idea here is to avoid signal degradation in the crossover, so why use low grade components on the crossover?
        If I spend the money on the amps, they'll be biased identically, and if possible I will omit any circuits in the X/O that let you adjust volume.
        I suppose if the bass got louder after switching to active bi-amping, you could attenuate the singal to that driver on the crossover.
        I'd then use a potentiometer to get the level you desire (using an SPL meter, test tones, etc). Once you have that, though, measure what the resistance you come up with and replace it with a high grade resistor)
        I just can't imagine that there'll be too much bass, but then that's what we're usually looking for with maggies :)
        Peter
        
        Re: MG 3a's vs MG 3.6 - akino 17:01:15 10/28/03 (3)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by pburke on October 28, 2003 at 10:20:58:
        
        I think what he means is that using a tri-amp setup, the passive crossover will be completely eliminated from the picture. Levels to bass, mid, and high will be controlled by the active crossover. I LIKE IT! I have to try this myself. Talk about eliminating components from the signal path!
        Andy
        
        Re: MG 3a's vs MG 3.6 - andyr 19:40:26 10/28/03 (2)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by akino on October 28, 2003 at 17:01:15:
        
        Andy,
        Thanks for jumping to my support but, strictly speaking, Peter is correct.
        Yes, the passive crossover is completely eliminated from the picture but the active crossover - or, at least, the one I have used - includes a pot to set the output level for that driver.
        To get the ULTIMATE in sound, yes, you could use this pot intially, set up your relative levels to how you want them, measure what the pot is reading and then replace it with a high-class (fixed) resistor.
        I'm not prepared to sacrifice flexibility for this.
        Regards,
        Andy
        
        Re: MG 3a's vs MG 3.6 - pburke 14:36:51 10/29/03 (1)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by andyr on October 28, 2003 at 19:40:26:
        
        just get a whole bunch of $20 Vishays and you'll have flexibility. You could even build an S5 type attenuator in the crossover
        There's always room to spend more money!
        Peter
        
        Re: MG 3a's vs MG 3.6 - akino 06:42:45 10/30/03 (0)
        
        In Reply to: Re: MG 3a's vs MG 3.6 posted by pburke on October 29, 2003 at 14:36:51:
        
        Aint that the truth!
        BTW sir...
        You have got a really nicely put together system. My compliments.
        Andy

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