Monitor Audio Rs6 Crossover

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mrbigswede

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Monitor Audio Rs6 Crossover
« on: 16 Oct 2015, 07:56 pm »
Jeff;
   Currently have stock crossover in 8 year old speaker that is geared for home theater. Stereophile  measured F.R. showed a rising spl of 5 db tween 1000hz-20000hz. Also a resonance showed up at 19000. Lots of 1000-5000hz minipeaks. Metal Dome tweeter exhibits good dispersion but can be harsh.  Recently ouputed my tube preamp to my P7 which has tone controls. A minus 4 db on treble put me in the right place . However , it was clear that I was masking some of the music. So now I'm looking at upgrading my crossover.

 Upon Inspection;
    Tweeter ; 2.2 ohm 7watt resistor, 6.0  250v cap (series)  :scratch:and a small inductor in the shunt position.
     Midwoofer;  .8mH coil , 4.0 100V  cap and another small inductor .-cap and inductor paralleling the driver (Zobel?)
      Woofer ; 5.0mH coil

Speakers were ~ $1500 msrp . Willing to spend 1/3 of that if real improvements are attainable.

A flat as possible FR  is my goal for this upgrade. As such I want to add a parallel resistor -22ohms across the tweeter and slightly increase the tweeter series resistor to 4ohm. This has been successful done on another forum.

Does what I'm suggesting make sense ? How far up the foodchain can /should I go re. caps? Resistors?

RDavidson

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Re: Monitor Audio Rs6 Crossover
« Reply #1 on: 16 Oct 2015, 09:41 pm »
Great topic. I also have RS6's and greatly enjoy their combination of strengths and versatility. I've had mine since 2007/2008 as well. They're not my main speakers anymore, but I still like them very much in the family room where they do a wonderful job with AV duties. When hooked up to midfi gear, the top end brightness / graininess is not nearly as noticeable as when I hook them up to my MUCH more refined and resolving main rig....which isn't at all a fair situation / comparison. It helped me understand what some have complained about with the RS6, though, and the complaints are definitely not unwarranted.

Coincidentally, one of the best synergistic matches I paired with the RS6 is the Cayin A50T, which has soft rolled-off top end (working well to subdue the speaker's top end energy). The midrange was magic. The bass was rolled off and a bit loose, though.

Anyway, if there's a crossover upgrade that is worthwhile vs just selling the RS6's and getting the newer Silver 6's, that'd be cool!
« Last Edit: 23 Oct 2015, 01:01 am by RDavidson »

Jeff

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Re: Monitor Audio Rs6 Crossover
« Reply #2 on: 20 Oct 2015, 05:02 am »
Real improvements are obtainable.  The best result is likely a complete rework of the speaker XO, but that is not very realistic.  Besides being costly...shipping speakers...etc...  If someone asks for the time, you do not tell them how to build a clock.

You do not have a schematic, so let me understand this better.  The tweeter is wired in phase with series 6uF cap closest to the input on the positive leg followed by a coil in shunt?  Between this and the tweeter, there is a series 2.2 Ohm resistor?

The upper bass driver is also wired in phase?  It has a coil in series on the positive leg closest to the input?  It is followed by a shunt that consists of a series 4uF cap and coil?

Woofer is in phase with a single 5mH coil in series to the driver.  I assume this to be correct as it sounds like a 2.5 way configuration.

Please advise.  Be sure of the order of components even if you must review the XO again.

mrbigswede

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Re: Monitor Audio Rs6 Crossover
« Reply #3 on: 22 Oct 2015, 11:59 pm »
Jeff;
     I apologize for the gibberish, I'll try to clear it up. follow the arrows >>>>>
Tweeter;
Terminal> 2.2 ohm 7watt RESISTOR > 6mF CAP > DRIVER with a small coil parallel to the driver.

Mid;
Terminal> .8mH COIL > DRIVER with a combination 4.0 100v CAP and a small coil parallel to the driver.

Bass;
Terminal> 5.0mH COIL > DRIVER 

It appears to me that the speakers are wired in phase. 

DIYAUDIO has a thread regarding the Monitor Audio S6/RS6  crossover mods that I have posted in.
Have you seen anything like this crossover? There are  references to the S6 ( original discussion) as well as the RS6 (MY SPEAKER)
The Frequency Response is much flatter with the S6 than the RS6. Drivers are the same, bass ports oriented differently  with a different crossover .

  System7 , (I assume you are familiar with him) is for significant add on components to deal with the metal cone trash as the source of what I'm hearing .There are also the stereophile mag. measurements that show both the rising H.F. and the spike above 15khz. I am worried about phase issues with such a drastic modification (butterworth and zobel on the tweeter, 10mF shunt on both woofers and an inductor upgrade), but I must say the these speakers don't image as well as I'd like now .So I am ready to jump to a more ellaborate crossover as a step two after the tweeter pad arrangement and some cap swapping. I think iif you saw the Stereophile measurements ,you would see where I'm coming from. As you can tell I'm green  as they come on this stuff but I'm ready to attack the semi-harrsh.  I guess if this means changing out/adding a resistor or two,I'm fine with the diy route . But it looks like it may be significantly more complicated than that for a substantial improvement.

By the way, where are you located in Texas? I'm in east Texas and willing to travel/deliver the speakers within reason.

What do you think and where do I go from here?

RDavidson

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Re: Monitor Audio Rs6 Crossover
« Reply #4 on: 23 Oct 2015, 12:59 am »
Really? I find their imaging one of their strong points.

Note, I've mine single wired with the positive cable going to the tweeter and the negative on the woofer(s). I played around with speaker wire connection schemes earlier this year and this was the best solution, short of maybe bi-wiring or bi-amping which I didn't try. If you haven't tried this, you should, at least as an experiment. It may give you clues as to where the weakest link(s) in the crossover are.

Additional notes:

I found that wiring both positive and negative leads to the top posts produced an overly bright sound and the highs seemed way ahead of the midrange and bass. The highs dominated the presentation horribly. Not pleasant to listen to.

Wiring both of the lower posts (as the manual recommends) produced a rather dull sound and phase doesn't seem quite right. Perhaps the highs were in better frequency balance, but timing was now really off. This was particularly noticeable with percussion instruments. Makes sense, right, as the crash of a cymbal or smack of a drum starts with a very high frequency first (produced by the tweeter). Certainly timing issues will affect imaging too.

This is how I arrived at the top post positive, lower post negative configuration. It is the best (most balanced) of the 3. Yes, I tried the reverse, with the lower post positive and upper post negative, but the effect was similar to having both lower posts connected, and isn't really worth mentioning.
« Last Edit: 23 Oct 2015, 04:07 pm by RDavidson »

mrbigswede

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Re: Monitor Audio Rs6 Crossover
« Reply #5 on: 23 Oct 2015, 03:38 pm »
Interesting - tried both top and bottom with a copper foil directional jumper in lieu of the supplied "bars" Not sure I heard a difference but ended up on the bottom pairs. I'll try your suggestion when I put back the crossover board and tweeter after Jeff and I figure out a strategy.

  I really think its significant that S6 ( prior model-same tweeter) and RX6 ( later model,new tweeter w/ lower crossover ) both had a flatter F.R.  than the RS6 . Clearly there is some marketing foolery at work here. I suspect the RX6 crossover to be more complex as well. 

RDavidson

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Re: Monitor Audio Rs6 Crossover
« Reply #6 on: 23 Oct 2015, 04:04 pm »
Well, not necessarily. Keep in mind frequency response is but just 1 aspect of a speaker's performance which would probably be more obvious in a direct A/B listening comparison rather than looking at measurements and drivers used. Note that the Stereophile reviewer found the RS6 and RX6 to sound essentially identical, but the latter had less high frequency energy (which corresponds with the measurements). I think there was a greater rework of the total design from the S6 to the RS6 (due to new woofers) than from the RS6 to the RX6 (which was a refinement of the long-in-the-tooth tweeter). Maybe the new midrange drivers in the RS6 made the engineers have to rework the crossover point, which caused the tweeter to distort more. Keep in mind these are "budget" speakers, and development of new drivers is expensive. My guess is that the goal (with budgetary constraints in mind) was first to design new woofers and make the S6 tweeter work with the new woofer as best they could.....until they could budget tweeter refinement in the next gen (RX6).

I don't see it as foolery at all. It's similar to the auto industry. They roll out a design with new tech. Then they make mid-model improvements a couple of years later. Then a couple of years after that, they roll out a new design with new tech again. I'm willing to bet the next gen Silver 6 will have "mid-model improvements" vs a new design.
« Last Edit: 24 Oct 2015, 06:05 pm by RDavidson »

mrbigswede

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Re: Monitor Audio Rs6 Crossover
« Reply #7 on: 24 Oct 2015, 04:54 pm »
You may be right about the new woofers. I didn't realize they were different.(S6 TO RS6).  I did read that the RX6 had a new tweeter that was crossed over at 2.7khz vs 3khz. I think this would imply that in concert with a crossover rework could/would cut out some of the mid woofer hash that system7 insists is the source of most of the HARSHNESS and must be addressed for good sound.

Hmmmm. Perhaps more than just the LPAD approach is required. Waiting for Jeff to chime in.

Jeff

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Re: Monitor Audio Rs6 Crossover
« Reply #8 on: 26 Oct 2015, 02:13 am »
DIYAUDIO has a thread regarding the Monitor Audio S6/RS6  crossover mods that I have posted in.

I finally got around to reading all six pages.

Quote
Have you seen anything like this crossover?

There was a time when I built XOs like that.   :(

Quote
System7 , (I assume you are familiar with him) is for significant add on components to deal with the metal cone trash as the source of what I'm hearing.

This is likely half of it.

Quote
There are also the stereophile mag. measurements that show both the rising H.F. and the spike above 15khz.

Yep, they reveal a resonance around 20k, but the spectral decay reveals a considerable amount of stored energy.  It "appears" to be a product of the resonance.  This is purely a driver issue.  It will have to be dealt with in the XO design.

Quote
I am worried about phase issues with such a drastic modification (butterworth and zobel on the tweeter, 10mF shunt on both woofers and an inductor upgrade)

You should be concerned without measuring equipment.

Quote
but I must say the these speakers don't image as well as I'd like now

You may have something else going on.  I have actually heard this screaming mimi.  I thought it imaged well.  The measurements show some off axis loss, but this might be because the mid is allowed too much upper bandwidth.

Quote
So I am ready to jump to a more ellaborate crossover as a step two after the tweeter pad arrangement and some cap swapping. I think iif you saw the Stereophile measurements ,you would see where I'm coming from. As you can tell I'm green  as they come on this stuff but I'm ready to attack the semi-harrsh.  I guess if this means changing out/adding a resistor or two,I'm fine with the diy route . But it looks like it may be significantly more complicated than that for a substantial improvement.

I'm glad to hear that you are ready to do what it takes, but the L-pad is not it.  Yes, it will lower the output, and reduce the excitement at resonance, but this is not dealing with the resonance.  By the time your L-pad has tamed the shrew, you will notice a lot has gone missing.

Quote
By the way, where are you located in Texas? I'm in east Texas and willing to travel/deliver the speakers within reason

I'm in Wichita Falls, and you?

Quote
What do you think and where do I go from here?

Mail me one XO assembly.

Jeff

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Re: Monitor Audio Rs6 Crossover
« Reply #9 on: 26 Oct 2015, 03:52 am »
Really? I find their imaging one of their strong points.

Note, I've mine single wired with the positive cable going to the tweeter and the negative on the woofer(s). I played around with speaker wire connection schemes earlier this year and this was the best solution, short of maybe bi-wiring or bi-amping which I didn't try. If you haven't tried this, you should, at least as an experiment. It may give you clues as to where the weakest link(s) in the crossover are.

Additional notes:

I found that wiring both positive and negative leads to the top posts produced an overly bright sound and the highs seemed way ahead of the midrange and bass. The highs dominated the presentation horribly. Not pleasant to listen to.

Wiring both of the lower posts (as the manual recommends) produced a rather dull sound and phase doesn't seem quite right. Perhaps the highs were in better frequency balance, but timing was now really off. This was particularly noticeable with percussion instruments. Makes sense, right, as the crash of a cymbal or smack of a drum starts with a very high frequency first (produced by the tweeter). Certainly timing issues will affect imaging too.

This is how I arrived at the top post positive, lower post negative configuration. It is the best (most balanced) of the 3. Yes, I tried the reverse, with the lower post positive and upper post negative, but the effect was similar to having both lower posts connected, and isn't really worth mentioning.

Interesting.  I applaud you for taking the time to do this.  I'll be interested to see this XO.  For clarification, are you using the factory jumpers?

RDavidson

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Re: Monitor Audio Rs6 Crossover
« Reply #10 on: 26 Oct 2015, 01:40 pm »
Good question. Actually I'm using some Anti-cable jumpers....which I'm really not sure are any better than just using a small piece of good OFC copper wire.
Something to note is that I think, even when using the factory brass links, you'd hear a difference in wiring schemes. It's really not subtle.

mrbigswede

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Re: Monitor Audio Rs6 Crossover
« Reply #11 on: 26 Oct 2015, 05:41 pm »
Jeff;
  Thanks for taking the time to jump into this! I use the copper foil I got from Mapleshade for the jumpers. A couple of points regarding imaging; I run a Rythmik subwoofer off the speaker leads ala REL . I have been trying to sync the subwoofers with RS6 for best sound which has me experimenting with flipping speaker leads on both the sub and the RS6. The power supply for the sub comes off the opposite side of my power panel. I convinced myself that I needed to flip the speaker +/- to get the sub phase right. In addition , the preamp I run requires a flip. Long story short, I have probably screwed up the imaging in the process of doing all this.

Recently bought a pair of the Dennis Murphy modified Parts Express kit and was extremely impressed with how musical and how good the imaging was.   Showed me the value of a good XO design - Got me moving on this Mod.

I am located south of Longview . I'd be willing to run both speakers up to you if we get to the end result faster. Two trips is ok, four trips-not so much.(recently retired). I'd much rather ship both crossovers to you at the same time than piecemeal it if we go that route.

 Keep in mind my budget for this is~ $500. (excluding gas back and forth) When we get into the discussion about caps for the tweeter, I have somewhat of an open mind . :icon_lol: 

I am much more into music these days than when I purchased these speakers in a surround system . I was told that a new set was out of the question. :nono:    My tastes point to tubes/vinyl music much more than movies. Front end is Modwright  enhanced Oppo 105D, VPI Classic / Soundsmith Zephyr II, Modwright LS-100 Preamp ,Parasound P7, Parasound A-52 Amp. and of course the MA Speakers.

  If you still want me to just mail one XO, I will. Just let me know.



mrbigswede

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Re: Monitor Audio Rs6 Crossover
« Reply #12 on: 24 Jun 2016, 05:08 pm »
The journey continues;
   After  several months of experimentation with modifying the crossovers  by adding an RC network across the tweeter , 3rd order capacitor to the tweeter (many different values) and a parallel capacitor to the LF driver , I ended up with only the RC  network with values of 8 ohm ,2.2 . The other modifications ended up removing so much valid musical information that left the music lifeless. I tried particularly hard to find a 3rd order capacitor  that wouldn't screw up the phase alignment with the mid -driver but was unable to while retaining the first series capacitor of 6.

   The RC network was successful in significantly reducing the HF harshness I was experiencing without robbing musicality. At this point ,I felt as thou I had achieved my original goal to reduce listening fatigue and a smoother presentation. 
 
  In the process of examining the XO board , Jeff identified the magnetic standoffs, driver wiring for mid and high ,binding posts and  capacitors and resistors as candidates for upgrades . The 4 coils were left alone. Since changing all of those components was inside my budgetary target , I went for it.  All but the binding posts have been running for over 75 hours now ...

  Soundstage has become a wall of images , slightly wider but very 3 dimensional. The previous conical blare was eliminated.  Layers of detail in good recordings were revealed . Things like ambiance cues,and reflections were evident.  What I thought was a smooth presentation, became much smoother ,more listenable. I am finding myself  listening at more volume dial  because of the ease of the presentation. Don't get me wrong, My speakers still have some issues but I spend most of my time listening to music now instead of listening to my equipment. Very satisfied!
 
 Jeff had told me early on that once I settle on the XO arrangement I will have attained some improvement in sound. He also told me that substituting the components that he recommended would take it to a whole new level. The new components have indeed exceeded my expectations. I have yet to install the new binding posts which should only augment the improvement.

 I have about $150 in new parts running in the speakers now. Even thou I had minimal soldering experience I had no trouble pulling this off. I did have quite a few "what if " phone conversations with Jeff during the experimentation phase and a few during the actual modification of the XO circuit board. He kept me straight during the entire process..  Thanks Jeff

 For those who can't hear the improvement in upgrading capacitors and resistors in speaker crossovers, I can only think that there is some part of your system that is overriding the benefit. Maybe my speaker was in the sweet spot for this type of upgrade.  Whatever the reason I AM EXTREMELY HAPPY that I finally bit the bullet.    :thumb: :thumb: :thumb:





Stimpy

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Re: Monitor Audio Rs6 Crossover
« Reply #13 on: 25 Jun 2016, 02:15 am »
This was a fun read, and I'm glad that your speaker sound quality has been improved.  I'd also love to see a before and after crossover schematic (if possible), to truly understand what's been modded?  Also, what brand(s) of capacitors were used, and where?

Thanks!

mrbigswede

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Re: Monitor Audio Rs6 Crossover
« Reply #14 on: 26 Jun 2016, 07:21 pm »
Originally;
   Tweeter  ;

          resistor =2.2, cap=6, in series
          coil = .25 in parallel,  resistor=8,cap=2.2 in parallel

   Mid  ;
          coil= .8 in series
          cap= 4, coil =.25 in parallel           

    Woof ;
          coil =5.0 in series

     Ended up adding the RC network in parallel at the driver-not on the XO circuit board

Used mills resistors for the new RC network as well as the original serial resistor.
Jeff will have to comment on the capacitors - these are very new and didn't have a brand name when I purchased them . Good synergy with metal dome drivers.