Question about Sunfire TGA-7200 Amplifier

5 Answers

I have a Lexicon MC12 HD EQ connected to a sunfire TGA 7401. speakers: L\R sunfire CRS-3 Center CRS-3C Surround CRM-2BIP sound is low even on 0dB gain on the LExicon. and there is an electric static crackling noise coming out of the sunfire power amp (Not Speakers) and the crackling noise is related to the content that is played. what could be the main reason for that and how can i fix the volume problem.this doesnt feel like 400w/Ch at all!!! i have the lexicon connected to 220v and the sunfire to 110v. Sunfire sent me a replacement after damaging the first one. when i damaged the first one, i opened up the power amp to check the damage.and noticed that each output board had 4 fuses. on every board, the same two fuses were blown as well as two transistors. sunfire replied to me and said that the cause of the damage was a ground loop! if so, how can i prevent damage to my replacement amp?

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  • 3 more comments 
  • omar991 Aug 22, 2010

    thanks for the info but how do i ground my equipment in the way that prevents a ground loop?

  • omar991 Aug 23, 2010

    what is the best way to ground the system in order to avoid a ground loop?

  • omar991 Aug 23, 2010

    what is the best way to ground the system in order to avoid a ground loop?

  • omar991 Aug 24, 2010

    how do i check the speaker with an OHM meter amd possible continuity with ground? and what should the meter read??

    your quick response will be greatly appreciated.

  • omar991 Aug 24, 2010

    Yes I have tried the RCA connection. Same thing. If u have an email I can send you a detailed system diagram with the connections and everything. It will give u a very clear idea about the system.

    And please provide more details on how to test ground loop and voltage on amp chasis. As well as steps for testing the speakers with a multimeter. Because a I'm suspecting that the center speaker is damaged. Because sound is not clear from it and it's much lower volume than the other ones although all channel gains are the same

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  • Master
  • 10,865 Answers

Hi Omar. In an electrical system, a ground loop usually refers to a current, generally unwanted, in a conductor connecting two points that are supposed to be at the same potential, often ground, but are actually at different potentials. Ground loops created by improperly designed or improperly installed equipment are a major cause of noise and interference in audio and video systems. They can also create an electric shock hazard, since ostensibly "grounded" parts of the equipment, which are often accessible to users, are not at ground potential. Take a few minutes to inspect your entire system. If you are not really into the technical aspects of your system, call in a pro as this problem will continue to haunt you until it is found and fixed. J.

Posted on Aug 25, 2010

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  • Master
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Hi,

Any updates on your connections?

Have you tried reconnecting the Sunfire using the RCA and

not the XLR , just for troubleshooting?

Please post to help you further.

Posted on Aug 24, 2010

  • 35 more comments 
  • Rommel Cana
    Rommel Cana Aug 24, 2010



    talking about Ground Loop?

    Measure using Voltmeter , if you can read voltages on each amp chassis with respect to ground it

    is bad.

    • Speaker will be later, you have check on it already , but we will go there don't worry

    After multimeter reading in ohms, it should be done actual to find the right phasing.

  • Rommel Cana
    Rommel Cana Aug 24, 2010



    you will also need to post what " source " you are using at the moment

  • Rommel Cana
    Rommel Cana Aug 24, 2010



    Ground Loop is two folds,

    One from the grounding and one from your Input grounding and phasing.


    • Indicate what AC source are you using for 220V?

    and your regular power line AC , Is it Normally 220V or 110V.

    • Please also indicate how it is connected.

  • Rommel Cana
    Rommel Cana Aug 24, 2010



    here are scenario 1,

    If your Normal Line is 110V , you need a step up for the 220V unit.



    Scenario 2

    If your Normal Line is 220V , then you need a step down transformer to 110V unit.


    • Please indicate , if your Units have three ( 3 ) prong plugs ( ground included )

    Or you are just using 2 conductors on each.

  • Rommel Cana
    Rommel Cana Aug 24, 2010



    • You may need to check also your XLR connections later , if you can attain a good quality

    sound using the RCA ( basic ) connection.

  • Rommel Cana
    Rommel Cana Aug 24, 2010



    • RCA connection is just to confirm if your XLR connection is OK.

  • Rommel Cana
    Rommel Cana Aug 24, 2010



    • if there is a large difference using RCA and XLR then you may need to interchange wiring on the

    Balance connections.

    • You might need to do it , One channel at a time ,.on each to confirm

    To find which channel are producing noise like you mentioned before.

  • Rommel Cana
    Rommel Cana Aug 24, 2010

    there are devices that can be installed on your Unit for Ground loop,



    Most often you can find one on your Cable provider.





    It is just for the purpose of isolating the ground on each, I also believe Sunfire have also.

  • Rommel Cana
    Rommel Cana Aug 24, 2010

    there are devices that can be installed on your Unit for Ground loop,

    Most often you can find one on your Cable provider.


    It is just for the purpose of isolating the ground on each, I also believe Sunfire have also.

  • Rommel Cana
    Rommel Cana Aug 24, 2010



    here is your guide:


  • Rommel Cana
    Rommel Cana Aug 24, 2010



    here are additional info about Ground loops:

    http://en.wikipedia.org/wiki/Ground_loop...

  • omar991 Aug 25, 2010

    my cideo source is a Lexicon bluray player connected to the Lexicon preamp through an ACCELL HDMI extender.

    sunfire power amp has a 2-prong power cable. Lexicon has a 2-prong power cable. Liberty XLR interconnects.

    in our country, we have both 110v and 220v. i have dedicated a 110v 15amp power line to the sunfire. and the lexicon is connected to a different 110v socket.

    i have also tried lifting the grounds from all equipment and connecting all equipment chassis with a ground cable in parallel then connecting the cable directly to the ground of the wall power socket. (wall socket has ground by the way, i have tested it) but still same problem.

    question: what if one of the speaker was blown or damaged. could this cause this problem> and could this damage the amp?

  • Rommel Cana
    Rommel Cana Aug 25, 2010



    you can send the image to premiumexperts@fixya.com and instruct them to send to palaboy

    give also the details on your XLR connection ( balance )

  • Rommel Cana
    Rommel Cana Aug 25, 2010



    We may have to measure first, if there is substantial voltage on the chassis of the Sunfire

    Amp ( without anything first )

    • If there is none, proceed with connecting the Lexicon then measure again, as long as there is

    no substantial voltage , proceed with the 'Source ".


    While there is still no substantial voltage , then it would be safer electrically speaking.



    • Here is what I want you to do, try to locate and identify what channel ( Sunfire )

    is always producing a weak sound .and damaging your fuse .

    have a note on it , and temporarily substitute ( that channel ) it with other speaker .


    • Do not play the Amp loud, just for you to have a nice listening level.


    Monitor again , if that channel still producing a weak audio .


    If it does , we may have to :

    a ) exchange the XLR cable with other XLR cable.


    If problem still persist ,

    b ) we may have to modify ( just for that Lexicon Output only )

    the XLR phasing just to compensate for the missing good audio that is supposed to be

    producing on your Sunfire Amp.


    or try


    c ) using an RCA connection


    and post what you found.

  • Rommel Cana
    Rommel Cana Aug 25, 2010



    If it is on the Center Speaker, do what i have posted above ,


    • Locate where it is connected ( marked that channel , Sunfire ) and have a note on it.


    these would be called project 2 Center Channel


    • if project 1 Chassis Grounding seems OK

  • Rommel Cana
    Rommel Cana Aug 25, 2010



    • Please also be informed that Chassis Ground , differs from Signal Ground ( XLR or RCA )

    These works differently.

  • Rommel Cana
    Rommel Cana Aug 25, 2010



    Here are additional guides:




    Troubleshooting





    Measure also the Resistance between the chassis of the Sunfire and the Signal Ground .





    How to use a multimeter





    and post what you found.

  • omar991 Aug 25, 2010

    I have been testing the speakers with a multimeter to check for any damage. As you know I'm using a sun fire CRS-3C for center. The Speaker has 2 binding posts. 1 for the woofers and 1 for the ribbonhttp://sunfire.com/manuals/CINEMA RIBBON CRS3

  • Rommel Cana
    Rommel Cana Aug 26, 2010



    I hope the speaker are still OK,



    here are additional info :







  • Rommel Cana
    Rommel Cana Aug 26, 2010




    • After verifying the resistance ( actually it should be impedance ),

    you may need to check it on your other amplifier first.

  • omar991 Aug 28, 2010

    i was testing the sunfire speaker with the multimeter yesterday and noticed the following: the CRS-3C has a boundry switch at the back (Wall, Room). when switched to ROOM I get a reading of 3.3 Ohms, which i think is quite normal for a 6 Ohm speaker. but when the switch is turned to WALL, i get a reading of 42 Ohms which is very weird.
    do you think the wall setting damaged my power amp?

  • omar991 Aug 28, 2010

    i was testing the sunfire speaker with the multimeter yesterday and noticed the following: the CRS-3C has a boundry switch at the back (Wall, Room). when switched to ROOM I get a reading of 3.3 Ohms, which i think is quite normal for a 6 Ohm speaker. but when the switch is turned to WALL, i get a reading of 42 Ohms which is very weird.
    do you think the wall setting damaged my power amp?

  • omar991 Aug 28, 2010

    i was testing the sunfire speaker with the multimeter yesterday and noticed the following: the CRS-3C has a boundry switch at the back (Wall, Room). when switched to ROOM I get a reading of 3.3 Ohms, which i think is quite normal for a 6 Ohm speaker. but when the switch is turned to WALL, i get a reading of 42 Ohms which is very weird.
    do you think the wall setting damaged my power amp?

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    from your comments:

    i was testing the sunfire speaker with the multimeter yesterday

    and noticed the following:

    the CRS-3C has a boundry switch at the back (Wall, Room).

    when switched to ROOM I get a reading of 3.3 Ohms,


    which i think is quite normal for a 6 Ohm speaker.

    but when the switch is turned to WALL,


    i get a reading of 42 Ohms which is very weird.


    do you think the wall setting damaged my power amp? "


    Here are possible scenario:


    • Any amplifier can work for as long as impedance of the load is not below 4 ohms.


    Having 42 ohms is too way far from an impedance of 16 ohms ( max )


    Having 42 ohms will have low output ( as you can hear before )


    Driving it hard , would cause the amp to burst.

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    • Having 3.3 ohms of 6 ohms is also far from Normal.( not good for amplifiers )


    these impedance ( speaker ) can also cause the Amp to work double time

    ( more current needed ) as used in a normal way.( may burst the amp also ).

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    I will post more , while i search for specs and schematics for your speaker,

    if you have more details , pass it on , so we can work these out, a more

    interesting is the 42 ohms ? or have an image of wiring ( only if you can )

    to guide you further how to check in step by step ,details.

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    from the binding post, ( 2 )

    you have a woofer and a tweeter.



    you can post impedance reading on:

    a ) reading for woofer only

    b ) reading for tweeter

    c ) reading for woofer and tweeter in parallel

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    from the image here:





    Assuming each of speaker is 6 ohms impedance


    first two on the left in series = 12

    3rd and 4th in series = 12


    Having there ends in parallel


    would produce 6 ohms.



    • You may have to check four speakers individually


    3.3 ohms is very dangerous for your amp.

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    you may have to get an image first or note , on it ( very important )

    on each of the speaker wiring.( speaker phasing )


    • you will need to disconnect either of the two terminal of each speaker.

    ( to test for impedance )


    • If all of it are OK ( impedance using the Multimeter ) then it could be on

    what you mentioned " Switch " ( could be bad )


    • Do not connect it to any amplifier until you got the right impedance ( total )

    on the four speaker ( in one box )

  • omar991 Aug 28, 2010

    i just want to know if a 6 ohm speaker reads 3.3 ohms on multimeter is normal or not. and the sunfire power amp can handle impadances down to zero.

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    • about the ribbon tweeter it passes through a capacitor before it goes out

    might as well check on both.

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    If it is a Fluke Digital Multimeter it is bad ( total speaker impedance )


    or you are referring to individual ?

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    it can handle zero , but not for long .


    Impedance of speaker changes when it is being powered .

  • omar991 Aug 28, 2010

    Total impedence is 3.3. test was done on the binding posts of the speaker

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    It also depends on how many power transistors are installed.

    MOSFET Power can endure , but not Discrete type ( but it depends also on the design )

  • Rommel Cana
    Rommel Cana Aug 28, 2010



    I would suggest take one woofer out and check , if it the same , post back

  • Rommel Cana
    Rommel Cana Sep 01, 2010



    here are additional info :


    • Impedance



    Speaker Impedance Explained - Ohms

    Speaker Impedance Matching



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  • Master
  • 15,935 Answers

Ground loop is caused by...
speaker wire hitting the basket of the woofer
grounded speaker wire
blown voicecoil
speaker leads (strands of wilre) touching opposite terminals at the amplifier.
Wire it all up EXCEPT the speakers - and check each speaker with an OHM meter for proper reistance and possible continuity with ground.

Thanks!!!!!!

Posted on Aug 23, 2010

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  • Master
  • 19,396 Answers

Hi.

Re:" the crackling noise is related to the content that is played.": That usually indicates that there is a fault in the preamp system, that would also explain the low dB in output but amp working (if it was the final, then no sound).

By the way, check grounding (earth on wallplug, bypass extension), and ensure there is no short in speakers connections (this must be done). If problem is an internal failure, as I suspect, then the unit must be tested at component level to find and repair the fault.

Posted on Aug 22, 2010

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  • 12,061 Answers

This can happen for a couple of reasons, ground loops, can occur when the ground connection between components is removed before the other one, like say one unit was ON,and then another unit that was switched OFF was removed from the system, like removing the interconnecting Audio cable. ON should always turn BOTH units OFF before doing any work, this includes the Power Cable to which must be BOTH removed from the wall, to eliminate any chance of a "Potential Difference" between equipment,
Now in the old days... ALL The Component(s) were connected with an individual Earthing wire that was grounded to each and every unit, so in effect they were all Earthed together. More importantly they were all at the same Potential, and there could be NO current flow between units.This is used to prevent this from happening. However this still doesn't mean one can disconnect from each other without FIRST removing them ALL from the power, before doing so.

Now As to another thing you can do, is get yourself some things called "PollyFuses" these are used to protect the speaker, under normal use they are a short circuit, BUT when there is a short circuit, and over a certain current rating is exceeded, below the amps Max Power, the very quickly and spontaneously go OPEN CIRCUIT,and stay there until short is removed, and then reset themselves upon removal of the short. These are invaluable.
Below is all about pollyfuses.
http://docs.google.com/viewer?a=v&q=cache:ifxFg7gkZa0J:www.electronicsforu.com/EFYLinux/efyhome/cover/sep2004/PolyFuse.pdf+pollyfuses&hl=en&gl=nz&pid=bl&srcid=ADGEESjr8DrkcoewNOKqBk6KNvIUcD0pLbuUI-aQm-gIq6L7E2lzw94SxRATF0O29Y56skTYWXpWG-bLATlJBnxK2NVkAg_XIZG-XccMDcaccLbube_mTvYmHUA8WvBEEaoGXlG-ZZnz&sig=AHIEtbTsf6XU-PBdKSQYRxHeEKSZsaNGUQ


http://docs.google.com/viewer?a=v&q=cache:wBv51OQQSRoJ:www.audioxpress.com/magsdirx/voxcoil/addenda/media/seaandland.pdf+audio+speaker+protector+device&hl=en&gl=nz&pid=bl&srcid=ADGEESitCmB_73aTD49bnXcXXMPqABb1k-6244F8iItc6ypKyTofvpxKdp-58RK-tMr-1xFyzYh8ugNNu7qzpmajgPdc6-uExfiQvtLJSJ8qI3D9P5z9aCXnWWqLA_Ky4SVbuOnbeFf5&sig=AHIEtbQNS-mqIWMm5gBj32jHEXN6O4WFow

Posted on Aug 21, 2010

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