Blackstone TL1 dead... x2

iamcheese
iamcheese Posts: 11
edited April 2011 in Troubleshooting
ive currently got some blackstone tl1 speakers hooked up to an onkyo tx-sr608 and a few days ago the front left and right speakers stopped working... odd eh? since i dont believe they were purchased from an authorized reseller (ebay store) i cracked one of them open and found that the resistor for the midrange had gotten very hot and melted some of the stuffing in the case... any ideas why this happened?
Post edited by iamcheese on
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    Welcome to Club Polk iamcheese! :smile:

    IMHO, 2 speakers at fault at the same time leads me to believe the original problem was not the speakers but elsewhere.

    The first thing you should do is with the help of your user manual, go in the speaker settings and make sure the receiver is set for 6 ohms minimum as any lower setting will damage those speakers (TL1 = 8 ohms speakers).

    As far as the resistor(s), I would suggest you call Polk to order the new ones. This troubleshooting section has direct link with Polk however, depending how busy the folks the response might be delayed when compaired with a phone call (direct assistance).

    Other Polkies will hopefully chime in soon with other advices.

    Good luck!
    TK
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  • BeefJerky
    BeefJerky Posts: 1,320
    edited April 2011
    I agree with Technokid on this. Both speakers going out at the same time leads me to believe the speakers weren't at fault. It's possible the receiver itself is the problem. I'm not sure I would even feel comfortable hooking it up to another set of speakers until I've had it tested. It may be putting out DC voltage on the speaker outputs which can very quickly kill a speaker. Hopefully the resisters blew before the drivers themselves got damaged.

    As for the receivers ohm setting, it would make no difference. All it does is limit the output of the amplifiers. At worst, you wouldn't be able to turn it up as loud prior to distortion.

    Also, just how loud were you playing them? Did you ever any distortion coming from them at all?
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    As for the receivers ohm setting, it would make no difference. All it does is limit the output of the amplifiers. At worst, you wouldn't be able to turn it up as loud prior to distortion.

    Also, just how loud were you playing them? Did you ever any distortion coming from them at all?
    According to the user manual for this receiver, the O/P wattage for that receiver is much higher in the lower ohm setting. However, the settings don't apply to receiver(s) sold in America (I just had a guess the OP maybe had the other countries receivwer as the OP never stated which country he is from). The American receiver and the TL1s are a good match as they both have the same power ratings so unless there is physicall damage to the receivwer or if the OP is listening at deafning levels, there is no reason for distorsion. I too wonder wonder how loud the system was played at...
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    i am in America... i didn't think to mention that before,

    and as for how loud were they... kinda loud but not maxed i dont remember exactly what level it was on, i didnt notice any distortion

    if it is my fault they died then learn from your mistakes right?
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  • BeefJerky
    BeefJerky Posts: 1,320
    edited April 2011
    TECHNOKID wrote: »
    According to the user manual for this receiver, the O/P wattage for that receiver is much higher in the lower ohm setting.
    Yes and no. What I stated above is absolutely correct. The receiver will lower the rail voltage to limit current output when set on the lower impedance speaker setting. When running an 8 ohm speaker with the receiver on a 6 ohm setting you will end up with less wattage. The reason it may have higher wattage on that setting when driving the lower impedance speaker is because that speaker will pull more current for the same voltage.

    V*I = W or voltage * current = watts
    Ohms law: V/R = I or voltage/resistance = current
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  • BeefJerky
    BeefJerky Posts: 1,320
    edited April 2011
    iamcheese wrote: »
    i am in America... i didn't think to mention that before,

    and as for how loud were they... kinda loud but not maxed i dont remember exactly what level it was on, i didnt notice any distortion

    if it is my fault they died then learn from your mistakes right?
    It's hard to say without having been there. However, there is an important test you should perform before hooking up any other speakers to your receiver. All you will need is a multimeter, preferably digital. Power on your receiver with no speakers or sources plugged in and set the meter to measure DC voltage. Test each of the channels with the multimeter by hooking the black and red test leads to the matching terminals for the receiver. There shouldn't be any significant DC voltage coming from any of the channels, and it should be pretty close to the same on each of them. There will probably be a small amount (in the low millivolts), which may be considered normal. Once you've done this, please post your results here.
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    keep in mind i dont know how well my multimeter works but all of the speaker terminals read at between 23 and 24 mV and the y read different every time i test it... so i think im gonna see if i can go find a decent multimeter somewhere... as i dont have like 400 dollars to buy a fluke right now
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    if it is my fault they died then learn from your mistakes right?
    The comments in that regard is not to imply it is your fault or not (as it is far from our decision to make) but simply part of the troubleahooting procedure to locate where exactly the problem is located (be receiver or speakers). Keep in mind the Blackstone TLs are fairly new products and Polk may have some to say about this thus my suggestion for you to contact Polk by phone to get their opinion on this. Polk can be trusted to lead you in the right path and take their responsibility if their is any issues with the speakers (this can happen with newer products).
    iamcheese wrote: »
    keep in mind i dont know how well my multimeter works but all of the speaker terminals read at between 23 and 24 mV and the y read different every time i test it... so i think im gonna see if i can go find a decent multimeter somewhere... as i dont have like 400 dollars to buy a fluke right now
    If I were you, I would wait before going any further with the receiver. Contact Polk first and see what they have to say.

    How old is the Onkio? Did you buy it new or used? Was is used with other speakers previously? Was it working fine before? Is there any warranty on the Onkio? Before you tamper with your receiver (especially if you are not familiar or at ease with troubleshooting) the above questions should be answered as if your Onkio is presently on warranty and you are tampering with it, you might void the warranty even if this was a manufacturing defect. We have to realize that not all companies are as open as Polk is when it comes to warranties. You should go step by step here and not burn bridges.

    Cheers!
    TK
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    the onkio is only about 4 months old, youre right though warranties are your, was on hold with polk and they closed while i was on hold :( will try again tomorrow

    thanks again guys :)
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    Yes and no. What I stated above is absolutely correct. The receiver will 1. lower the rail voltage to limit current 2. output when set on the lower impedance speaker setting. 3. When running an 8 ohm speaker with the receiver on a 6 ohm setting you will end up with less wattage. 4. The reason it may have higher wattage on that setting when driving the lower impedance speaker is because that speaker will pull more current for the same voltage.V*I = W or voltage * current = watts
    Ohms law: V/R = I or voltage/resistance = current
    1. Lowering the rail voltage will limit the wattage output NOT the current as the current and voltage are inversely proportional and furthermore current is constant in a series circuit.

    2. You pointed out that the voltage rail is lowered at the lower ohmnique value and since the voltage and current are inversely proportional, knowing that the output wattage is higher with lower ohmnique speaker(s), value the current flow could be higher at the output and (not knowing if the blown resistor if the resistor is in series or paralell) IMHO, the current flow may have been too much for the resistor and thus fried it. The receiver may have been bought in the US but does not prove it does not have the ability for different ohmnique value settings until verified and proven.

    3. Actually, since the current is constant in series and voltage drop is dependant of the ohmnique value (V=IR) the higher homnique value will try to push more watts than desired through that speaker thus overheating of its circuit.

    4. Exactly, the lower setting actually pushes more current to the speakers and this is not desired in an 8 ohms speaker.

    In my repair shop, I often had to repair receivers where people had used lower ohmnique value speakers. IMHO, this is the other way around, using the higher speaker ohmnique value with lower ohmnique value of the receiver would cause damage to the speaker rather than the receiver.

    If my assumption is correct and the resistor is in series, this may have been designed by Polk to protect the driver. Using a resitor fuse for example, the resistor would fry to protect the driver.

    iamcheese, you could verify this by measuring the ohmnique value of the speaker at the post. Test this as is at first and it should read an open (trying to read the an open driver). If it actually doesn't read open but rather read close to the 8 ohms, that would mean the driver is not affected and that resitor is in paralell in the circuit. On the other hand, if it reads open this resistor might be in series or the driver coil is open. Now to prove that either the resitor or driver coil is opened, use a wire with aligator clip to bypass the resitor and measure again if you can see the driver ohmnique value. If you can see close to 8 ohms, this mean the driver is still good and that series resistor is open.


    Cheers!
    TK
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    iamcheese wrote: »
    the onkio is only about 4 months old, youre right though warranties are your, was on hold with polk and they closed while i was on hold :( will try again tomorrow

    thanks again guys :)
    Then, your first step is to check/work with both companies. If possible, try get Onkio to provide you with an authorised repair shop to check your Onkio for defects. It would be nice if they paid the tab for this (warranty) but this has to be determined by them. Even if you have to pay a few $$ of your pocket to make sure your receiver is fine (always get an estimate from the shop before authorisinf any repair). Then once the receiver is proven not to be at fault it is much easier to work with Polk in determining the issue (and vice versa of course).

    Good luck and keep us posted (if receiver is OK, some Polk CSR will eventually show up and be in a better position to help you).
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    yeah, i am going to play phone ping pong, i think there is an authorized onkyo repair shot about 30 miles south of me so that wouldnt be a problem to drive it down there


    no im not sure if i tested right but i tested the speaker i have open and i couldnt get any readings at all off of the driver even if i tested right on it and bypassed everything on the board with the resistor... i did get a 3ohm reading off of the tweeter though tested right on it, if wit will help i can see about uploading a picture of the board i have out of the speaker case, im kinda new to the game when it comes to this type of stuff... usually work on game consoles and such.

    let me know if i should do a picture
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  • BeefJerky
    BeefJerky Posts: 1,320
    edited April 2011
    TECHNOKID wrote: »
    1. Lowering the rail voltage will limit the wattage output NOT the current as the current and voltage are inversely proportional and furthermore current is constant in a series circuit.

    2. You pointed out that the voltage rail is lowered at the lower ohmnique value and since the voltage and current are inversely proportional, knowing that the output wattage is higher with lower ohmnique speaker(s), value the current flow could be higher at the output and (not knowing if the blown resistor if the resistor is in series or paralell) IMHO, the current flow may have been too much for the resistor and thus fried it. The receiver may have been bought in the US but does not prove it does not have the ability for different ohmnique value settings until verified and proven.

    3. Actually, since the current is constant in series and voltage drop is dependant of the ohmnique value (V=IR) the higher homnique value will try to push more watts than desired through that speaker thus overheating of its circuit.

    4. Exactly, the lower setting actually pushes more current to the speakers and this is not desired in an 8 ohms speaker.

    In my repair shop, I often had to repair receivers where people had used lower ohmnique value speakers. IMHO, this is the other way around, using the higher speaker ohmnique value with lower ohmnique value of the receiver would cause damage to the speaker rather than the receiver.

    If my assumption is correct and the resistor is in series, this may have been designed by Polk to protect the driver. Using a resitor fuse for example, the resistor would fry to protect the driver.

    iamcheese, you could verify this by measuring the ohmnique value of the speaker at the post. Test this as is at first and it should read an open (trying to read the an open driver). If it actually doesn't read open but rather read close to the 8 ohms, that would mean the driver is not affected and that resitor is in paralell in the circuit. On the other hand, if it reads open this resistor might be in series or the driver coil is open. Now to prove that either the resitor or driver coil is opened, use a wire with aligator clip to bypass the resitor and measure again if you can see the driver ohmnique value. If you can see close to 8 ohms, this mean the driver is still good and that series resistor is open.


    Cheers!
    TK

    1) You are somewhat correct. Lowering the rail voltage will not directly lower the current, however, it will indirectly lower the current. With x impedance speakers and a lower rail voltage, those speakers will pull less current.
    "current is constant in a series circuit"
    That is only true if both the voltage and impedance remain the same. I refer you to Ohm's Law.

    2) The current flow would only be higher when the receiver is set to the lower impedance setting and he was using a 6 or 4 ohm speaker. He was using 8 ohm speakers, so the lower rail setting would've meant lower current and therefore lower wattage. Once again, I refer you to Ohm's Law.

    "voltage and current are inversely proportional"
    This only applies if you are keeping the third value the same (watts or ohms)

    However, you might be right about the resister blowing to protect the driver. However, this should only happen in his situation if the receiver was driven into clipping.

    3) Current is only constant if the voltage is. Again, when changing the rail voltage, the current will change as well with the same speaker system. You are correct that with the higher ohm setting on the receiver the speakers can pull more current. However, at the 8 ohm setting, his receiver is pretty well matched to his speakers, so I doubt it is a matter of too much power.

    If anything, it might be a matter of too little power. If he is running in surround mode, the overall wattage per channel will decrease since the rated power is only for 2 channels driven. An underpowered receiver driven into clipping is more likely to damage a speaker than a higher powered receiver. However, the OP said he did not hear any distortion, so that is not necessarily the issue either.

    4) The lower setting can only end up supplying more current if you are running a lower impedance speaker. Yet again, I refer you to Ohm's Law.
    IMHO, this is the other way around, using the higher speaker ohmnique value with lower ohmnique value of the receiver would cause damage to the speaker rather than the receiver.
    This would only be the case if the receiver is driven into clipping. The receiver will not deliver more current or watts to the same speaker system when set to the lower impedance setting.

    Honestly, I'm quite sure the problem in all this is your failure to understand Ohm's Law and how it relates to speaker impedance.
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  • BeefJerky
    BeefJerky Posts: 1,320
    edited April 2011
    iamcheese wrote: »
    keep in mind i dont know how well my multimeter works but all of the speaker terminals read at between 23 and 24 mV and the y read different every time i test it... so i think im gonna see if i can go find a decent multimeter somewhere... as i dont have like 400 dollars to buy a fluke right now
    This sounds like a perfectly reasonable DC offset. Unless your meter is way off or defective I doubt that is your issue. Unless there is an intermittent issue with your receiver. However, those are incredibly hard to track down and identify. As such, it would likely be beyond the scope of what we can troubleshoot over a message board.
    if it is my fault they died then learn from your mistakes right?
    As TK said, we didn't intend to imply anything. At this point, we still don't know for sure what cause the speakers to fail.

    As for the warranty, nothing I instructed you to do would in any way void the warranty. The case was never opened; you simply measured the DC offset at the speaker connectors. In fact, I doubt I would ever instruct you to open the case over a message board. I don't know your skill level, and I certainly wouldn't want to suggest something that could be dangerous or void a warranty.
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    well good news, got ahold of polk and they are gonna take care of it, thanks for all the help
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  • BeefJerky
    BeefJerky Posts: 1,320
    edited April 2011
    iamcheese wrote: »
    well good news, got ahold of polk and they are gonna take care of it, thanks for all the help
    Good to hear! Polk CS is awesome, and I'm not surprised they took care of you.
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    iamcheese wrote: »
    well good news, got ahold of polk and they are gonna take care of it, thanks for all the help
    Two thumbs up for Polk again!:cool: Keep us posted on your findings and fixes.
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    TECHNOKID wrote: »
    Two thumbs up for Polk again!:cool: Keep us posted on your findings and fixes.

    will do!

    i was thinking of replacing them with some tsi100s or similar if they wouldnt cover them :) id get 200s but the room is kinda smallish for them

    will post back probably Monday when they get back to work and check on the email i sent back to them with the info from the speakers
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    iamcheese wrote: »
    will do!

    i was thinking of replacing them with some tsi100s or similar if they wouldnt cover them :) id get 200s but the room is kinda smallish for them

    will post back probably Monday when they get back to work and check on the email i sent back to them with the info from the speakers
    Just keep in mind that even if you had to pay your self for the resistor it will not be that expensive and worth while. Upgrading is a good idea if you feel like it and have the funds but just make sure you do not waste good speakers just to avoid doing minor repair. Make sure wathever you do that you go through a recommended-authorised dealer as it saves you time money and headache. :wink:

    BTW, it is a matter of choice but I just would like that nowadays you get better deals on the Monitor(s) than the Tsi(s) and IMO, they are just as good.
    DARE TO SOAR:
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    TECHNOKID wrote: »
    Just keep in mind that even if you had to pay your self for the resistor it will not be that expensive and worth while. Upgrading is a good idea if you feel like it and have the funds but just make sure you do not waste good speakers just to avoid doing minor repair. Make sure wathever you do that you go through a recommended-authorised dealer as it saves you time money and headache. :wink:

    BTW, it is a matter of choice but I just would like that nowadays you get better deals on the Monitor(s) than the Tsi(s) and IMO, they are just as good.


    i actually have a set of the resistors that need to be replaced but i dont wanna go soldering stuff if they are gonna cover it :)

    and i just noticed i can get a pair of monitor 30s for about 89 to 100 bucks or 4 of them for the price of a single pair of the tsis... better yet the look of the monitors matches the psw505
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    iamcheese wrote: »
    i actually have a set of the resistors that need to be replaced but i dont wanna go soldering stuff if they are gonna cover it :)

    and i just noticed i can get a pair of monitor 30s for about 89 to 100 bucks or 4 of them for the price of a single pair of the tsis... better yet the look of the monitors matches the psw505
    Good deal for the Monitor 30s, hard to pass, right?:wink: Just make sure they come from an authorised dealer.:wink:
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    went ahead and ordered them... from a link to an authorized dealer i found on the site :)
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    an an update: i got the replacements from polk... very fast iam gonna say, they said i could keep the bad speakers for spaire parts... i felt one of the drivers and it was very stiff and grinding, so i took it apart and found the coil on it was completely toast and unraveled, also the 5ohm resistor on the crossover was overheated and actually split in two,

    i am very happy with polks service and will definately continue to buy polk audio gear :)
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  • pdxfj
    pdxfj Posts: 376
    edited April 2011
    iamcheese wrote: »
    an an update: i got the replacements from polk... very fast iam gonna say, they said i could keep the bad speakers for spaire parts... i felt one of the drivers and it was very stiff and grinding, so i took it apart and found the coil on it was completely toast and unraveled, also the 5ohm resistor on the crossover was overheated and actually split in two,

    i am very happy with polks service and will definately continue to buy polk audio gear :)

    Glad to hear they took care of you. It is customer service like this that makes a customer for life. Sadly a lot of places don't even have 1/10th the level of customer service Polk has.
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  • TECHNOKID
    TECHNOKID Posts: 4,298
    edited April 2011
    iamcheese wrote: »
    an an update: i got the replacements from polk... very fast iam gonna say, they said i could keep the bad speakers for spaire parts... i felt one of the drivers and it was very stiff and grinding, so i took it apart and found the coil on it was completely toast and unraveled, also the 5ohm resistor on the crossover was overheated and actually split in two,

    i am very happy with polks service and will definately continue to buy polk audio gear :)
    Good on you and bless Polk! :cool: Make sure you get your amp checked before you hook-up those new TLs on it.:wink:
    DARE TO SOAR:
    “Your attitude, almost always determine your altitude in life” ;)
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  • iamcheese
    iamcheese Posts: 11
    edited April 2011
    im thinking it probly just got turned up too loud :( gonna set the max volume setting on the receiver i think
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