1. Rest in Peace Paul (Kegger) If you would like to help the family in this time of great sorrow and need, you may donate on their GoFundme page: https://www.gofundme.com/mckechnie-medical-and-funeral-fund?
    Dismiss Notice

IRS Gamma measurements

Discussion in 'Infinity Loudspeakers' started by WSU, Jun 3, 2017.

  1. WSU

    WSU New Member

    Messages:
    9
    Hello,

    as a quite new Gamma owner I couldn’t find measurements about this speaker. Therefore I made some measurements, maybe the information is useful for somebody.

    First I measured impendance in different poti-settings. In my Gamma the „MIN“ position of the LEMIM should be avoided due to different impendance curves between the speakers in this position


    First box no.1 with poti in „min“ position (with passive network for the woofer section)
    1.jpg


    Box no.2 with potis in „min“ position shows a different behaviour between 200-500Hz (with passive network for the woofer section)
    2.jpg
    [​IMG]



    Beside that between 9am -3pm the curves a pretty similar between box 1 and 2.




    Below some measurements for different poti postions (10 dB scale). Given the results of the impendance measurement I avoid min/max position by only using the potis between 9am -3pm.

    LEMIM: Blue 9am, red 12, green 3pm
    3.jpg
    [​IMG]



    EMIM: Blue 9am, red 12, green 3pm

    [​IMG]
    4.jpg


    EMIT: Blue 9am, red 12, green 3pm
    5.jpg
    [​IMG]



    SEMIT: Blue 9am, red 12, green 3pm

    [​IMG]
    6.png



    Finally a comparison of the woofer section. Active, with SCU at 164Hz, Bass Contour +5/-5, without DIN-cables and with DIN-cables connected (green and blue), which balances upper and lower bass.

    [​IMG]
    7.jpg



    Hope that was interesting for you,

    Wolfgang
     
    Seppo and Thereimade12 like this.
  2. Mark B

    Mark B Yamaha Fan Subscriber

    Messages:
    5,005
    That is very interesting Wolfgang. I've got the Delta version of these speakers.

    Great first post & welcome to AK!
     
  3. WSU

    WSU New Member

    Messages:
    9
    Thank you Mark!
     
  4. goodolpg

    goodolpg AK Member Subscriber

    Wow, way beyond my understanding but could help others.
    Welcome to Ak.
     
  5. geoff727

    geoff727 Well-Known Member

    Messages:
    653
    Location:
    Seattle, WA
    Thanks for posting. Are you doing far-field measurements for the woofers? It looks like there's quite a roll-off below 37Hz, going to about -11dB from average by 20Hz. I would have thought, with the servo function, these would be much flatter to 20 if the measurements are taken near-field and the baffle step taken out of the equation. But, then, I really don't know too much about the Gammas.
    G~
     
  6. WSU

    WSU New Member

    Messages:
    9
    Hello Geoff,
    it is a near field measurement to avoid room effects.

    Wolfgang
     
  7. rvito

    rvito Active Member

    Messages:
    315
    Any pictures?
     
  8. WSU

    WSU New Member

    Messages:
    9
    Hi rvito,
    yes, see attached pic for the woofer measurement. The mic (MiniDSP with REW) was 2 cm in front of the control woofer. The Linkwitz Sub in the back was not playing.

    20170604_155937.jpg

    Wolfgang
     
  9. geoff727

    geoff727 Well-Known Member

    Messages:
    653
    Location:
    Seattle, WA
    So I'm assuming that the bass rolloff is a product of time gating of the measurement, with the rolloff being dependent on frequency periods longer in time than the measurement gate. Would you agree? In other words, if the measurement were taken far-field, un-gated, and had all room reflections and standing wave modes present, the response between 20Hz and 37Hz would raise.
    Geoff
     
  10. WSU

    WSU New Member

    Messages:
    9
    Hi Geoff,
    yes, that is correct, the response would raise and the -3dB measured in the room is actually the 20Hz you mentioned.
    Wolfgang
     
  11. 7.62

    7.62 Gearhead Subscriber

    Messages:
    628
    Location:
    Las Vegas
    I'm with goodolpg, way above me. But I hope before my dirt nap comes, I get to hear a pair. That's my dream speaker.

    Congrats. And welcome.
     
  12. WSU

    WSU New Member

    Messages:
    9
    Yes 7.62, it's definitely worth to wait. I was amazed from the sound quality of the Gammas. Even after 30 years they are top speakers.

    I have measured different settings of the Servo LP Filter and finally ended up with 164.

    First the different settings:
    1.JPG


    And finally the 164 setting only, including the sum. The actual/real crossover point between the woofers and the LEMIN is 125 Hz in this setting.

    2.JPG

    Wolfgang
     
  13. geoff727

    geoff727 Well-Known Member

    Messages:
    653
    Location:
    Seattle, WA
    Interesting. The summation suggests a slight suckout in the mid-bass region between roughly 85Hz and 175Hz. Do you have any polar response graphs for these? I'd be curious to see what the response is at 30 degrees, 45, and 60, and see if there's any fill-in to the sides in that region.
    G~
     
  14. WSU

    WSU New Member

    Messages:
    9
    Hi Geoff,

    I made some measurements on axis (red) / 30 degrees (blue) / 60 degrees (green), but not sure if they are useful. They were made in the room, distance 2 meters / 6.5 feet (with subsonic in 40Hz position). Due to the distance the room may distort the measurement.

    Winkel.JPG

    Wolfgang
     
  15. geoff727

    geoff727 Well-Known Member

    Messages:
    653
    Location:
    Seattle, WA
    Yes, maybe. Through that 100Hz to 200Hz range, there are some differences in the basic shapes of the curves, which is interesting. The two off-axis curves have a distinctly different shape than the on-axis curve does. I'll have to think about that for a while. I hesitate to say that it's because of the horizontally-mounted LEMIM; the frequencies in that area have wavelengths much larger than the driver itself so the horizontal mounting should have very little effect as the driver is acting like a point source. Is your gate short enough to preclude getting reflections into the measurement?
     
  16. WSU

    WSU New Member

    Messages:
    9
    Hi Geoff,
    due to the low frequency range in the measurement and the distance of 2meters I have not used a gate. Therefore the reflection are in the measurement.

    Btw: I saw that you own a Magnepan 1.6. I have a chance to hear a pair but it would take me a few hours driving. Are the mids/highs are comparable to the emim/emits or maybe even better?

    Wolfgang
     
  17. geoff727

    geoff727 Well-Known Member

    Messages:
    653
    Location:
    Seattle, WA
    Well, these 1.6's are kind of a special case. The frames are much more substantial than stock, while still fitting the stock grill "sock" around them. The driver panel, held on by staples in stock form, now has a retaining frame with 99 screws torqued down to a fairly careful setting, and incorporating constrained-layer damping between the driver retaining frame, the driver panel, and the main frame. The speakers are propped up with sand-filled MyeStands, instead of the stock footers. And, they are fully active. The passive crossovers are taken out and the crossovers are implemented with dual Bryston 10B L-R's, one in three-way mono mode for each side. The low end, crossed over at 50Hz, is taken up by a stereo pair of Rythmik Audio F12SE's. Fortunately, these speakers are conducive to using an off-the-shelf 24dB/octave crossover, as they don't really require using a notch or boost filter in any specific frequency range or any other fancy implementations. It alters the preferred positioning of the speakers a bit, as the 24dB/oct. units have outputs that are in-phase; therefore, sitting on-axis between the high- and low-range panels produces a very coherent output. This is not quite so for the stock speaker, as the passive crossovers induce the typical component delays through the networks. If I remember right, Magnepan recommends sitting slightly off-axis to the inside of the speakers to account for this.

    The 1.6's are a single-ended planar, EMIT's/EMIMs are dual. These Magnepans have magnets on only one side of the diaphragm. Inevitable, this will produce distortion artifacts as the diaphragm excurses and moves into slightly different regions of magnetic flux. EMIMs/EMIT's won't have this problem, but they will have a different problem...cavity resonance due to the dual-sided magnet structure. May not be much of a factor with the EMIMs since they are crossed over at a point well below where the cavity resonance should occur. The EMIT's, I have never really sat down to think about where the resonance would be.

    I have not done a direct comparison between these and an Infinity planar-based speaker. But, I have listened to RS-1b's and these in different environments on the same day on several occasions. My impressions were...
    1. The RS-1b's are softer presentation. A little bit looser. The Magnapan's have more of a "laser-beam-like" focus to things. This is especially true in vocals, where I've had a lot of "Whoa!" moments.
    2. The planar-magnetic treble panel of the 1.6 doesn't get the very top end quite right. With their lower mass, I think EMITs are a much better high-frequency driver. 1.6's have what is typically known as "Maggie grain", a slight hardness to the sound that becomes noticeable after a while of listening. The ribbon Maggie speakers sought to overcome this, and I think it's virtually disappeared in the newest 3.7 and 20.7 versions.
    3. The mid-bass of the Maggie is HUGELY better than the RS-1b's woofer towers and EMIM's operating at the low end of their range. Interestingly, when I first brought them home (in stock form), they had a looseness to the midbass that I wasn't sure I could live with. After i modified them and converted the system to active, that transformed into some full and very defined midbass. When there's a trombone going BLATT, the speakers reproduce a trombone going BLATT. For example, the Tuba Mirum in Mozart's Requiem is just fantastic. The trombone and male baritone vocals are regions where the speakers excel.
    4. The integration of the Rythmik woofers into the low end where the dipole makes the bass drop off is pretty good. Not perfect in my current environment, but at least as good or better than any servo-based Infinity I've yet heard. I've heard the Beta's on a few occasions over the last few years, and I think the Maggie/Rythmik setup is easily their equal over this frequency range, if not better.

    So, the system is good, but loses ground when it comes to the really high frequencies. For the 1.6 to be a truly excellent system, I think it would have to cut the treble panel over to a high-quality ribbon around 3,500Hz or so, and perhaps then to an integrated Sopranino electrostatic super-tweeter. I think that would bring the highs up to the quality of the midrange/midbass/low bass areas.

    If I had to choose, I'd probably take the Beta's over this system, with the idea of doing some tweaking to the system and seeing if Paul McGowan's team could rebuild the servo controller with some more modern componentry and power supply. However, I'd choose this system over the RS-1b's in almost all cases.

    Geoff
     
  18. WSU

    WSU New Member

    Messages:
    9
    Hi Geoff,
    thank you for the detailed reply. Based on your impression I have fixed a date to listen at the Maggies. I found the the highs of the Infinity RS/IRS line are a bit to much (maybe because they were developed with a tube amplifier which has already a rolloff above 10kHz?). Since the mids are more important to me I'm curious to hear the 1.6. I have also noticed the Bryston 10-B, which I did not know.

    Thanks again,
    Wolfgang
     
  19. geoff727

    geoff727 Well-Known Member

    Messages:
    653
    Location:
    Seattle, WA
    Sounds great. Just keep in mind, mine are a completely different animal than stock. Compared to the originals, the dynamics, definition, and coherence of my system have improved drastically. On the flip side of that, the fairly low efficiency of the system (around 86dB, I think) requires that that power really be put to it before it starts to open up. And sometimes, I've felt that this is accompanied by a bit of strain. Hard to describe, just more of a 'gut' feeling than anything. Sometimes I find myself turning up the volume control more and more saying, "Come on baby, you can do it!"

    So I wouldn't say they're a permanent system for me. I'd like to have something that can do what these do in the midrange, bass, and mid-bass, but that has superior highs and a higher efficiency. But, for what they cost me ($2,000 for the speakers brand new, $2,000 for the 2 crossovers used, $1,000 for each subwoofer, $500 for the MyeStands, roughly $200 in structural tweaks and binding posts), it is very hard to find much better in an overall system.

    So I'm not sure how you feel about the stock version. If the Infinity high-frequency range is not your cup of tea, you might think even less of the 1.6. You might have to listen to a 3.7 or 20.7 to find a more accurate high end. Looking forward to your impressions!

    Geoff
     
    Last edited: Jun 19, 2017 at 12:14 PM

Share This Page