IRS Gamma Servo Control

Discussion in 'Infinity Loudspeakers' started by jtucker, Dec 21, 2009.

  1. buddyiramae

    buddyiramae New Member

    Messages:
    22
    Location:
    Terrell Tx
    No more buzzing, good news indeed! I am in Texas, east of Dallas. Let me know how you progress & count on my help, if you are nearby. Enjoy the Gammas, great speakers!
     
  2. audiomagnate

    audiomagnate AK Subscriber Subscriber

    Messages:
    7,694
    Location:
    Atlanta
    Yeah, but the fixes or upgrades are usually cheap and easy. Terminals back then were just done much more cheaply back then. Congrats on the repair. I would just bolt it back up at this point and use it. Ground is ground after all.
     
  3. engelder2

    engelder2 New Member

    Messages:
    12
    Location:
    Texas
    Update on RCA Terminal Repair. Since the buzzing stopped when I jumped the ground of the RCAs from input to output, I thought I might be able to just solder a wire to the bottom of the board connecting the bad input ground to one of the other grounds. Wrong, I discovered the break was somewhere between the board and the RCA barrel, so I had to unsolder the entire plastic housing as both input and bypass RCAs are on the same 2X2 strip. When I removed the plastic insulator, I noted that the break was just above where the ground terminal goes into the board. I found a replacement at Mouser and ordered it; hopefully it won't be backordered.
     
  4. SicMan

    SicMan Fire up those speakers Subscriber

    Messages:
    3,030
    Location:
    Wolcott - CT. USA
    Yep they break by pushing the connectors in a little harder or which I think is just a bad design problem. No stress relief or weak plastic.

    Glad you found it.

    John M
     
  5. engelder2

    engelder2 New Member

    Messages:
    12
    Location:
    Texas
    Servo Circuit Working???

    Everyone,

    Well, I was able to successfully solder the new RCA jack to the PCB, and the unit is working with no hum at all, so we are good there. However, now I am uncertain if the servo feedback section of the unit is working or not. I tried the "tap" test that is noted in the users manual, but I get nothing from the other channel's woofer. Is there another way to determine if it is working or not?


    Thanks,
    Mark
     
  6. SicMan

    SicMan Fire up those speakers Subscriber

    Messages:
    3,030
    Location:
    Wolcott - CT. USA
    When you tap 1 only that side will do what they say in the manual not both. If you do not get a response in one by tapping that one there may be an open in the system, or the woofer with the feedback sensor (3rd one up) may be bad or disconnected. OR there's a problem in the servo amp.
    You can swap the woofer towers and check that way. Just don't cross the wires. OR swap the feedback cbles to see if its a cable.
    I had a loose connection in one of my woof towers, bad solder joint. There all soldered 14 gauge wire inside these. On the woofers.

    John M
     
  7. engelder2

    engelder2 New Member

    Messages:
    12
    Location:
    Texas
    Feedback Testing

    Hello John (& others),

    I tried the "tap" test the way you describe (servo unit on, speaker wire and feedback cable connected) one channel at a time, but I still don't get any sound from the slave woofer in either the Right or Left channels. I thought that maybe I could determine if any voltage is coming from the control woofer by connecting my meter to the feedback terminals on the woofer, but I don't get any reading whatsoever with AC Volts, DC Amps, or DC volts on the lowest settings. I attached a photo of my control woofer terminal for the feedback cable. It appears that everything is connected properly, and this is where I was taking the readings...right at the terminals. I understand that there is some sort of piezo unit under the dust cap, but at this point I don't want to remove it (the dust cap) if there is some other way to determine the control woofer is sending voltage back to the SCU. Is this voltage too small for my meter? Do I have to have the speaker connected to the SCU with a signal present and then take the readings? Any thoughts? I really appreciate everyone's help so far!!!
     

    Attached Files:

  8. engelder2

    engelder2 New Member

    Messages:
    12
    Location:
    Texas
    Servo/Acceleromoter Fixed...I think?

    Thanks to all who have helped me so far. I believe I have finally found the issue with the accelerometer/SCU, and I'm almost too embarrased to respond with my findings.

    Since I couldn’t get any measurements at all at the accelerometer leads, and recalling that many of the posters here said do not completely trust any of the Infinity schematics on the internet, I pulled the slave woofer out of the enclosure and traced the accelerometer leads back to where they are soldered to the DIN connector on the inside of the crossover. I double checked orientation, and discovered the red and black leads are soldered to the other two terminals instead of the ones that I was using (I had initially fabricated my cables according to the Infinity schematic on the web without checking this earlier). I also double checked connections at the SCU DIN connector, and sure enough this confirmed it. (obviously, the bare drain wire is correct). So……I cut my cables, restripped, and re-soldered to the other two terminals on each of the 4 pin connectors, hooked it all back up, and it seems to be working. Someone mentioned on another post that if you pull the accelerometer cable while the unit is on and playing music, the SCU (green) light will go out, and sure enough I tried this and it did.

    However, I’m not 100% sure (maybe 90%) that the system is working correctly. It may be, and I just don’t know. I tried the tap test again, and I really don’t hear that much sound from the lower slave woofer, but again maybe it is not that pronounced? It doesn’t say in the users manual how loud the "thump" should sound in the slave woofer, but I played some music last night and heard very low bass sounds that I’ve never heard before with any speakers I’ve owned. So, again, it may be working properly, and I just don't realize it. Can anyone confirm how loud the slave woofer should reproduce sound or vibrate when the control woofer is "thumped"?

    Thanks again to everyone for their help
     
  9. Nikkoholic

    Nikkoholic Active Member

    Messages:
    284
    Location:
    St. Louis, MO
    Mentioned the correct DIN connects a few posts back #9 and #12 That is what was wrong with mine.

    As for the tap test. I did a "push" test. With the system on, everything, including the amp and preamp. Push very lightly on the woofer with the accelerameter. When doing this it will push back. The system knows there is no signal going to the woofer, and when it detects movement, the servo unit knows there is not supposed to be movement, so it sends a signal to correct the position and pushes back. It is a bizarre feeling, and there will be no question as to whether it is working or not. Remember push very lightly it doesn't take much.

    My beta's have been gone for about 2 years, but this is what I recall.

    Good luck and hope you got them working correct. Phenomenal bass when working properly, muddly sloppy bass when not.
     
    Last edited: Apr 30, 2013
  10. engelder2

    engelder2 New Member

    Messages:
    12
    Location:
    Texas
    Hello Nikkoholic,

    Yes, you are absolutely correct about the previous postings concerning checking the accelerometer cables back to the DIN connectors. I even said I would check these at that time, but didn't think this wiring could be wrong. Again, this just confirms the obvious...do not trust the Infinity schematics; double check everything yourself.

    I tried the "push" test the way you describe, but don't feel the control woofer pushing back, but your logic does make sense. I recently refoamed all four of the woofers; could it be that the cone compliance is too "stiff" at this point (due to new surrounds) and would need to break in?

    Also, I do notice a difference between when I tap the control woofer with the servo on, versus when it is off. The thump sound is more pronounced on the slave woofer when the servo unit is on. Would this be the result of the accelerometer section in the SCU, or just the electronic crossover section?

    P.S. Why did you get rid of your Betas? I was looking for a pair of Betas for some time until these Gammas came up for sale, so I grabbed them.
     
  11. Nikkoholic

    Nikkoholic Active Member

    Messages:
    284
    Location:
    St. Louis, MO
    push test would be with everything on, including your amp and preamp.
    If it doesn't work, my knowledge beyond that is limited to none.

    Had the Betas for about 2 years. Prior (and during) I owned QLS-1 for 30 years. Loved those speakers. Bought Rennaissance 90's and Betas later to try something different for a change. Betas seemed like the ultimate for Infinity (within my financial reach). Once working properly they were great, but there were some things I didn't like. Mainly there was a midrange weakness to them. I have several pieces of music that I listened to and was very familiar with, but on the Betas, some of the instruments were very quiet and almost inaudible. I tried to correct this with equalization, and that helped but not completely. Upon further investigation and reading I found a review (informal) that completely described my findings. After that it was a bit mental and I couldn't get past it.

    I also had a fear of a Large EMIM going bad. If so replacement would be unlikely, unless it were used. Unlike conventional drivers these just aren't easily repaired. There was a guy who was tooling up to make some small EMIN replacements, and he did (Graz?), but not the large EMIM. Since the Beta's had 4, it seemed dissasterous if one ever failed. Saw one on auction for about $1000 and only 1 (in about 3 years). So if failure happened you would be left with parting out what is still good, or some repair, or some make shift substitution.

    So I decided to go with new and sold them and all my old infinity. I did in fact write Infinity a letter regarding their complete abadoning of all their premium customers. For those of us that bought the great Infinity stuff and made them who the are (were) really felt abadoned. They obviously have the tooling, even if they were to run a lot of parts every few years, it would have been nice to have some form of replacments available.

    Had they gone out of business, I understand. But to just drop everything, even as current as the mid 90's (with the Ren 90 speakers).....no parts for any of it.

    Off topic of your thread, sorry.
     
  12. ac81017

    ac81017 New Member

    Messages:
    3
    I´m new to this forum, i´ve just bought both IRS Gamma and Beta. I followed the connecting instructions in the manual, I ended with a humming noise. I´m no expert in electronics. I read the manual 3 times to tripple check my connections, the red marked cabled is in the right channel. Was wondering if there is a left and right speaker? I couldn´t find any markings on the IRS Gamma. I will only connect my IRS Beta when i´ve fixed ym IRS Gamma. The swith on the back of the servo is on 0db..
     
  13. dobbhill

    dobbhill Vinyl Addict

    Messages:
    218
    Location:
    Louisiana
    The red is not the right.
     
  14. crwilli

    crwilli Active Member

    Messages:
    341
    Location:
    Eastern PA
    Can't speak to the Gammas but there is no difference between the left or right betas. Even if there is on the gamma, I suspect but not sure that it would only be for proper alignment of the EMITs like it is for the RSIIa/b's. I don't see why it would matter to the servo.




    Sent from my iPhone using Tapatalk
     
  15. crwilli

    crwilli Active Member

    Messages:
    341
    Location:
    Eastern PA

    Can you expand on your comment? Are you referring to the servo cable with the red band on it?

    I ask because on studying, I mean really studying the instructions for my Betas, I have found the figures do no not match what the words say for connections.

    The figures show left to right while the words clearly say everything must be right to right, - to -, etc. I have followed the words which I have done before but cannot get my servo to stop going into overdrive! It is frightening.


    Sent from my iPhone using Tapatalk
     
  16. dobbhill

    dobbhill Vinyl Addict

    Messages:
    218
    Location:
    Louisiana
    The RCA jacks are installed like most others: Black(or white) on top for left, and red on bottom for right. The SCU has the right channel connected to the black jack which is on "top."
    It does not follow the usual arrangement that many are accustomed to. Therefore, can lead to catastophic results...would be better if all the jacks were "black."

    But then, if I were standing on my head.....

    D
     
  17. Nikkoholic

    Nikkoholic Active Member

    Messages:
    284
    Location:
    St. Louis, MO
    Responding to this on my cell phone
    But there are 2 "bad" noises related to betas
    1- due to servo connections / problems
    2- due to gain settings

    Take a look at this thread for problem #2
    http://www.audiokarma.org/forums/showthread.php?t=299425

    Didn't read all of the above so if this is redundant I apologize
     
  18. crwilli

    crwilli Active Member

    Messages:
    341
    Location:
    Eastern PA
    All the RCA jacks on my servo unit are black. I have heard that not all Beta servo units are like that however.
     
  19. michigannick

    michigannick AK Subscriber Subscriber

    Messages:
    698
    Location:
    Michigan
    Hi guys ..I am the owner of a set of Delta's and recently drummed up a servo control but lack the 4 pin DIN, I see references all over the the pin out for making a set of cables but I cant seem to find them on any forum, maybe my google skills have deteriorated but I am just not having luck, I get that it appears I will need to positively validate the internal wiring but that will come as i build a set of cables once i find the directions if someone here can help I would appreciate it!
     
  20. rvito

    rvito Active Member

    Messages:
    321
    There's a guy on eBay (no affiliation) that sells a lot of infinity parts. He has the cables
     

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