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"I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ...

120.148.114.16

In Reply to: RE: Interesting question - hopefully you will get more input than mine. :-)) ... posted by josh358 on March 19, 2012 at 19:22:13

Valid point but it seems that Mr Gunn produced a good-sounding 3-way mod using 6dB (series) XOs? At least, his customers thought so (the only complaint I've ever seen - the F111 pilot - was complaining about the woodwork, if my memory serves me.)

Regards,

Andy

Follow Ups:

RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - josh358 10:00:47 03/20/12 (14)
As DR said, the results weren't so good, though I don't think we were ever absolutely sure that it was the crossover (the problems were in the midbass IIRC and the listening room has a big effect there).
It's actually pretty hard to do a single pole crossover, because of the much higher demand it puts on the drivers vis a vis mass, power response/dispersion, IM, power handling, and resonances/breakup.

Edits: 03/20/12
- RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - Satie 10:16:26 03/22/12 (1)
  Gunn's mods include rewiring the 3.x models into a 2 way. This results in an overwhelmingly big midrange.
  
  Davy (UK) is reporting very good results with his 6 db mods to the 3.3.
  
  The bass still has to be done in 3rd order and possibly 2nd (he dumped his behringer so can't confirm and his current active is fixed 3rd order).
  - RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - josh358 16:02:09 03/22/12 (0)
    Very interesting.
    
    I was going to pass on something I just read about IV woofer crossovers on Arthur Salvatore's site, but then I read two letters from you (and one from Mmlrot1), so I figured you'd already read it.
- RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - Dawnrazor 10:03:25 03/20/12 (11)
  I agree Josh, but then why did magnepan move to 1st order on the new mmgs?
  
  I always thought it was to mess them up in relation to the 12s so that there was a reason to trade up...
  
  Afterwards we discovered faith; it's all you need
  - RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - josh358 10:29:52 03/20/12 (10)
    I figured it was to save money. They also leave off the bypass cap. Also, they did redesign the MMG's tweeter when they made the change. The narrower tweeter would have a different polar response. I think the main point is that you have to tune the speaker for the crossover and vice-versa. Forex, if there's a resonance in your driver a bit above the crossover point, like the one Satie pointed to in the 3.x woofers, you have to either use a sharper crossover or change the driver to eliminate the resonance. Conversely, he was able to use the 6 dB/octave driver with his IV's because they were designed to cross at about 350 Hz and he's crossing them over lower to his Neo-8 midrange.
    
    Here's another photo of the 3.7 woofer panels, you can see that they've changed the tuning substantially, and there's no more clamp, rather an acoustical filter made out of tuning dots. These look more like 3.5-way speakers now, with sort of a physically sliding frequency range:
    
    http://www.avguide.com/blog/first-listen-magnepan-s-new-flagship-207-loudspeaker?page=1
    
    This should improve power response and I think reduce crossover lobing.
    - 6dB slopes ... - andyr 12:35:30 03/20/12 (9)
      Well at some stage soon, I'm going to prove it - one way or the other! :-)) After discussions with Satie, the mulleted midget and (the English) Davy, I intend to substitute 6dB boards into my active XOs ... except that I'll keep the current 18dB bass LP slope.
      Regards,
      Andy
      
      Edits: 03/20/12
      - That's the spirit laddie! - JBen 13:23:28 03/20/12 (8)
        
        In Reply to: RE: 6dB slopes ... posted by andyr on March 20, 2012 at 12:35:30
        
        Now, if we could only get you properly set up to measure the response of the Frankies before and as you make those changes!
        
        Measurements - probably not, mate! Could nae be bothered :-)) ... - andyr 14:56:44 03/20/12 (7)
        
        In Reply to: RE: That's the spirit laddie! posted by JBen on March 20, 2012 at 13:23:28
        
        I am only interested in how they make me feel , after the change. :-))
        
        So I'll substitute the new XO board having:
        * 6dB mid HP
        * 6dB mid LP, and
        * 6dB ribbon HP
        
        ... and leave my existing 18dB bass LP board in place. This will require me to flip the ribbon polarity so that it's now the same as the mid (which is inverted, relative to the bass). Getting the ribbon connected in the same polarity as the mid is the only reason for doing this change, IMO - and then I'll start listening to all my favourite pieces of music, to see if I like it better. :-))
        
        Measurements I'll leave to engineers like Davey! :-))
        
        Regards,
        
        Andy
        
        RE: Measurements - probably not, mate! Could nae be bothered :-)) ... - JBen 17:42:27 03/20/12 (3)
        
        In Reply to: RE: Measurements - probably not, mate! Could nae be bothered :-)) ... posted by andyr on March 20, 2012 at 14:56:44
        
        Yes, the "feel" is key.
        
        Being a possessive bastard, I tend to measure after a change that makes me feel good. This helps to insure that I can replicate that "feel good" experience later. It quantifies a few things for reference; as a practical mix of the subjective and the objective. It often also suggests ways to fine tune for a better feel.
        
        LOL! Davey will soon show up and set us both straight. You have a couple of intentions listed there that should do nicely to ruffle his engineering feathers.
        
        Anyway, one of my favorite bi-amp PLLXO configs has both MMG drivers in the same polarity, in 1st order. To do so and still retain the same tonal personality (while adding other attibutes), the tweeter high pass cap has to be different, and the level adjusted.
        
        If I measure this vs my other 1st order xover version with the mic, I'll get the same pretty flat response. They virtually overlap. One inverts electrically, the other doesn't and yet, tonally, they are the same. The difference is in the soundstage each one projects. I am guessing that it is a phase-related thing. There are caveats but that is another story.
        
        OTOH, my most accurate (to me) bi-amp xover config is one that pretty much mimics the original 1st/2nd order slopes; what these old-version MMGs came with. This is what I use most of the time.
        
        So, I have 3 PLLXO configs that I can live happy with. If any of them starts sounding wrong, a quick mic reading may suggest that someone messed with the system...or, more likely, confirm that I just had too many beers. : - ))
        
        "The difference is in the soundstage each one projects." ... - andyr 18:18:53 03/20/12 (2)
        
        In Reply to: RE: Measurements - probably not, mate! Could nae be bothered :-)) ... posted by JBen on March 20, 2012 at 17:42:27
        
        Interesting to read that.
        
        Was it you who posted about the audience applause & whistling at the beginning of HFOT "Hotel California" coming from above & behind ... and I then posted that this didn't happen with my setup?
        
        If so, that's the sort of result I'm hoping will be produced by my mids being in the same polarity as my ribbons, with the 6dB XO.
        
        Regards,
        
        RE: "The difference is in the soundstage each one projects." ... - josh358 09:49:05 03/21/12 (0)
        
        In Reply to: RE: "The difference is in the soundstage each one projects." ... posted by andyr on March 20, 2012 at 18:18:53
        
        Above and behind usually has to do with high directionality, the absence of room reflections, or suppression of interaural crosstalk, as well as *relative* phase between the two speakers (being exactly centered, and also maybe having any early reflections timed right).
        
        RE: "The difference is in the soundstage each one projects." ... - JBen 18:34:20 03/20/12 (0)
        
        In Reply to: RE: "The difference is in the soundstage each one projects." ... posted by andyr on March 20, 2012 at 18:18:53
        
        Well, the impression I got was that the LP recording that you have is of a different Hotel California session. Even if it is the same, it may be that the LP renders it differently.
        
        Luckily, there's an easy way to find out. Let me not clog the thread...check email in a few minutes for an idea.
        
        RE: Measurements - probably not, mate! Could nae be bothered :-)) ... - Dawnrazor 17:27:23 03/20/12 (2)
        
        In Reply to: RE: Measurements - probably not, mate! Could nae be bothered :-)) ... posted by andyr on March 20, 2012 at 14:56:44
        
        Hey Andy,
        
        I thought you had to reverse the polarity even on the 1st order slopes. Well the current mmgs have the polarity reversed but have 1st order slopes.
        
        Neo did his best to explain it but I didnt FEEL like getting it :)
        
        Afterwards we discovered faith; it's all you need
        
        "I thought you had to reverse the polarity even on the 1st order slopes"??? ... - andyr 17:35:53 03/20/12 (1)
        
        In Reply to: RE: Measurements - probably not, mate! Could nae be bothered :-)) ... posted by Dawnrazor on March 20, 2012 at 17:27:23
        
        My only experience with this comes from simulating many (certainly scores ... and maybe over 100) Maggie XOs in lspCAD.
        
        I have found that the "normal" situation with 6dB XOs is that the drivers need to be connected with the same polarity (and this is what I see as the big advantage with 1st order slopes ... which outweighs the problems associated with increased driver overlap. etc) - otherwise a big hole opens up at the XO point.
        
        But every now and again, I found that a particular combination of LP & HP roll-off points required the tweeter to be flipped, to get rid of the hole.
        
        So have no idea what causes this behaviour - simply that it happens. Maybe Davey could give you a more technical expose?
        
        Regards,
        
        Andy
        
        RE: "I thought you had to reverse the polarity even on the 1st order slopes"??? ... - neolith 06:01:55 03/22/12 (0)
        
        In Reply to: RE: "I thought you had to reverse the polarity even on the 1st order slopes"??? ... posted by andyr on March 20, 2012 at 17:35:53
        
        For a symmetrical 1st order crossover (same fc), polarity is irrelevant except perhaps to those freaks who can hear absolute polarity. Let's assume the phase at frequency x for the LP is 0 deg., then the phase for the HP is 90 deg. and the difference is 90 deg. Inverting the polarity on the HP makes it -90 deg. and the difference is still 90 - same difference. Now for asymmetric 1st order xo's the phase difference are not the same (not 90 deg) at all frequencies so inverting will result in a different phase difference. If the fc are far apart, then one may get the drops in the output and inverting may correct this.
        As an example here is a bode diagram for the MG-IIb. The fc's of the LP and HP are 2 octaves apart and you can see the drop out for the same polarity that flattens with the inversion.
        
        And here is a Bode diagram for a symmetric 1st order XO that crosses at the same frequency. Note the output only shows as a white line (the magenta line coincides and is obscured). The output is dead flat and if you look at the phase plots they are are always 90 deg apart.
        
        �
        
        On the violin: "Heaven reward the man who first hit on the idea of sawing the innards of a cat with the tail of horse."
RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - tyu 08:50:20 03/20/12 (0)
Maybe...
RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - Dawnrazor 08:46:25 03/20/12 (7)
Hey Andy,

I think your memory is a bit off.

Anyhow here is a bit from the review:

So am I happy? No, I would have to say this was not a forward step for me after listening for the past couple of months and tweaking for the best sound compromise I could achieve in my room. The stock 3.6R's had a more "seamless" sound with cohesive soundstage and balance between the frequencies. They had to be "pushed" more for their best sound, but could be listened to for hours as reasonable high volumes levels. The Magnestand 3.6R's are better at conversational levels, but I believe the stock 3.6R is better everywhere else. I have a lot of $ invested and cannot afford to sell them at a loss, so I will apply my own expertise and see if I can get them a little more balanced to my taste. This is not the first step backward I have taken in 42 years and it won't likely be my last. It's part of the journey.

See the whole post below and I thought that Saties post about 1st order crossovers was interesting. And I dont recall another 3.6 owner with this mod, but we have seen how memory is a funny thing so I could be wrong :)

Afterwards we discovered faith; it's all you need
- http://db.audioasylum.com/mhtml/m.html?forum=mug&n=157077&hi (Open in New Window)
- RE: "I'm not sure that the 3.6 would allow you to use single pole crossovers without compromising performance" ... - patmacav 20:27:26 03/21/12 (0)
  I read through the posts since you so thoughtfully provided the link and I have to wonder.. PG started doing mods initially on SMGs, MG1s, and the smaller two way Maggies and I believe that these speakers come tilted back away from the listening position and are tilted away on his Magnestands. So, I was wondering if his mods to the 3.6Rs included tilting the speaker back like is done with the smaller models and if so, if this might lead to the gaps or holes in the soundstage that Varkdriver was describing.
  
  I have no idea, but I was just curious.
  Good day
- They started to grow on him 3 months later - sbrians 17:06:32 03/20/12 (5)
  His system was updated 3 months later and contains this comment:
  "Magnestand mod is growing on me, but the jury is still out"
  - RE: They started to grow on him 3 months later - Dawnrazor 04:01:01 03/21/12 (4)
    Hi SB,
    
    You are right, I had missed that.
    
    But I dont know if that is such a ringing endorsement since that line is listed under system weaknesses !
    
    IIRC Waz went through that with his modded speakers. It took him a while to get used to them and then he did, but ultimately went back to stock.
    
    It will be interesting to see what Andyr concludes.
    
    Afterwards we discovered faith; it's all you need
    - RE: They started to grow on him 3 months later - old guy 42 09:23:18 03/21/12 (3)
      Hi. DR
      
      In regard to the inmate with the Gunned 3.6's---- IIRC, he specifically changed-out his pre-amp to acquire a pre-amp with TONE CONTROLS.
      
      old guy
      - LOL - Dawnrazor 00:05:52 03/23/12 (2)
        
        In Reply to: RE: They started to grow on him 3 months later posted by old guy 42 on March 21, 2012 at 09:23:18
        
        A tone control to counterbalance the one built into the speakers!! Not that is so music lover it is crazy!
        
        Hey Old guy 42!!
        
        Jben and I thought you passed or something. We were at this club he takes me to. It is the same old thing, some cuban band is playing and the drinks are flying and then he smiles and takes out his papers full of measurements. My eyes glaze over and I look around the room. But last tuesday when I looked, I saw this old dude slumped over and drooling. "Holy crap, its old guy 42", I said.
        
        Jben looked perturbed and grabbed another stack of papers. These were drawings of faces. Then he said, "Close. That is old guy 43. 42 probably passed making that MM842R cable. Now look at this graph Dawnrazor"
        
        I have been thinking about your config of magwire. The "old guy twist" i'll call it. I think it might make a great interconnect. If you give me a while I will make such an IC and maybe a few other configs. I can send them to you and you can see which ones you like. I dont really have any rca connections these days so those extra tips I have are kind of useless. I was thinking too that we could send them to some other inmates and see what they think as well. Would 3 ft be enough?
        
        Afterwards we discovered faith; it's all you need
        
        RE: LOL - old guy 42 08:25:43 03/23/12 (0)
        
        In Reply to: RE: LOL posted by Dawnrazor on March 23, 2012 at 00:05:52
        
        Hi. DR
        
        First of all---My condolences to 43's family.
        Second of all--My apologies to the OP.
        
        As I read your account of the evening at the club with Jben....At the table, I pictured you as Flash Gordon and Jben as Dr. Zarkoff. Then, Dr. Zarkoff tells Flash.."Pay attention, this is important!!! And forget about a lap-dance, Flash".
        
        Your story was truly, funny as hell!!!!
        
        I took your advice and made a second pair of speaker cables and wired it shotgun. Still, great clarity, a bit fuller, and the best, so far, imaging.
        
        In regard to ic's, you flatter this old, tech. challenged, guy with "old guy twist". I have read pros & cons in the cable asylum about star-quad ic's. I think I would consider Al's idea about the Highwire RFI coils. Only 10 bananas at Music Direct. As far as construction goes, I was going to put 5 runs of 100% cotton yarn in the drilled holes of the wood pieces. Then attach the 30 ga. & twist and then wrap with teflon tape and then slide on the Tech Flex. I was going to wait till August to do this, and I would be very interested in knowing how you would build the ic's. Also, I would be super-happy to have an ic made by you!!! I just need a 24"er for my Thomas Edison..errrrr my CDP.
        
        I think the Star-Quad works for my speaker cable because of the close proximity of my amp. to the aux. AC outlet that I tried to hide from my wife.
        
        I also think that I took up enough of your time. Next time...Listen to Jben :-))
        
        Take care....old guy
        
        RE: LOL - JBen 07:57:28 03/23/12 (0)
        
        In Reply to: RE: LOL posted by Dawnrazor on March 23, 2012 at 00:05:52
        
        LOL! You did leave out the part where you stealthily left me hanging with the tab. Serves me right for mixing with too smart folks.
        
        Hey, last night I was making preparations for an upgrade to the Stixbees. The MMGs wound up on their original stands, fully leaning back and with no Stixbees...just the Razoring. I had never heard them this way (slanting back + Razoring, no frame reinforcement). So, it was a chance to hear what the rest of the mods do with just your tweak, on "full slanties".
        
        It was rather good...actually, surprisingly good. I might as wll mention that the Razoring benefits have held just fine over the almost 2 years since I installed the tweak. You can now increase the warranty to 2 years and charge a little more. : - ))
        
        I did make a few quick frequency scans just out of curiosity...not that you would care for that kind of thing, lol!

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