Polk Monitor 70 Series 1 Tweeters Almost Silent

I created the same question/thread, over in the troubleshooting forum:
http://forum.polkaudio.com/discussion/184140/polk-monitor-70-series-1-tweeters-almost-silent#latest

I figured I'd give it a shot here as well, please see below or follow the link I guess. If this is a double post or something I suppose someone will delete this.

The TLDR would be:
1. Monitor 70 Series 1 tweeters are almost silent.
2. Replaced tweeters with RD0093-1 which match both original tweeters
3. New tweeters are just as quiet.
4. Verified all connections and other components are correct and operating normally
5. Not knowing otherwise, it sounds to me like the rest of the speakers are working fine

I'm dealing with a pair of Series 1 Monitor 70's, purchased in the early 2000's. While tinkering about I noticed by themselves they sounded a bit off. I couldn't quite place it until I hooked up an old Monitor 7. After some testing I concluded it must be the tweeters. I ordered a set of replacement tweeters, not from Polk (I know, I know yell at me later)... Anyway the new tweeters arrived and I installed them. They sounded the same, which is to say, I cannot hear the tweeters without putting a paper towel tube up to the tweeter and adjusting volume accordingly. I unhooked the 70's, removed the jumper, and ran the speaker wire to just the top binding posts for high frequency only. I have to crank my volume to about -10 to just get something resembling sound. I understand it's possible the replacement tweeters are bad but I am wondering if there could be some other problem. I am not at all adept at troubleshooting a speaker's crossover or internals. I have swapped in speakers to make sure the rest of my equipment is functioning and not causing the problem.

Are the Monitor 70 Series 1 tweeters just inherently exceptionally quiet? If not, does this sound like a problem with the speaker's crossover or other internal component/s? How should I go about troubleshooting the internals? I haven't opened them up yet because I don't really know what to look for apart from very obvious scorching or something like that. If the problem is with the internals, is it something worth trying to fix, or have serviced by someone with know how? I consider myself savvy enough but my technical knowledge in this area is lacking. I suppose with some guidance and a hell of a how to, it's something I can tackle.

I'm running a Yamaha RX-A840 which is feeding a Crown XLS 1002 which powers the two Monitor 70's. All connections have been checked and double checked. I have run both the Monitor 70's and Monitor 7's off just the Yamaha and the Crown, no matter the combo, the Monitor 70's tweeters are almost silent.

My apologies for a long post, thanks in advance.
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Comments

  • pitdogg2pitdogg2 Posts: 14,719
    edited November 2018
    Did you check the tweeter resistors on the crossover? Maybe they have been cooked. Take a picture of the crossover and post it here. I'm not sure but does it have 4 binding posts.
    By the way it's not necessary for multiple threads.
  • Thank you for the input. Yes, the monitor 70's have four binding posts. I'll take pictures of the crossovers and post them. I'll have to wait until morning before I can get to it though. My apologies for multiple threads. I wasn't sure if one section was better to post in, so I chose both.
  • pitdogg2pitdogg2 Posts: 14,719
    Are the jumper plates in place and all binding posts tight?
  • I got around to taking those photos. My knowledge is limited but it looks like I have a blown capacitor on both crossovers. Beyond that assumption, I've got nothing else. Any and all input is appreciated.

    Thank you

    M 70 #1

    4stai5chd1v1.jpg
    uv758094mmzd.jpg
    4hlpc3ckc6vs.jpg
    sil1rd5rd2qo.jpg

    M 70 # 2

    75zolmprbssk.jpg
    q5rccwoo10yf.jpg
    ll7trpwttsyd.jpg

  • pitdogg2pitdogg2 Posts: 14,719
    edited November 2018
    I can't disagree with that. You have two choices, get a film cap that will not go bad big would be much larger or another non-polar electrolytic that will eventually do the same.
    The film cap will be much bigger and one would need to get creative to attach to the board but it can be done.
    Film cap would be the route I'd take.
  • I am entirely open to a recommendation as to which film capacitor and where to get them. I know what a capacitor looks like and have a very general idea as to what they do. Aside from that I am lacking in knowledge. I'm confident I can do the de-solder/solder job but if you're saying a film cap will be much larger, there's not much room on that board as you know. There's plenty of space on the underside of the board. I'm not sure if that's an option or not and if it would affect how the capacitor is installed.

    If you have a suggestion for the soldering iron, I am open to that. I do not currently have one and its been years since I've messed about but I'm generally capable if I know exactly what to do. Something like this https://www.amazon.com/Magentos-Superb-Adjustable-Temperature-Soldering/dp/B0744P55YR/ref=zg_bs_3207126011_2?_encoding=UTF8&psc=1&refRID=P4GZ8GDFR0ZQ4R1AXB25 seems like it ought to work as long as I can manage the rest.
  • FestYboyFestYboy Posts: 3,737
    edited November 2018
    30 watt pencil should work just fine. Get a spring vacuum, or some solder wick. If you have a tight get budget, Dayton will work well and be an improvement over the electrolytic. Placement on the back of the PCB won't make a lick of difference.

    *** I read the item description: states it's for 200v mains... May want to verify it's intended input voltage before ordering.
  • pitdogg2pitdogg2 Posts: 14,719
    edited November 2018
    What is the value? Sorry I'm too lazy to download schematic.
    In this instance i really can't argue the dayton.

    Yea that link for you I'd be all over it
    Got everything you'd need.
    Zip tie cap on back.
  • pitdogg2pitdogg2 Posts: 14,719
    edited November 2018
    FestYboy wrote: »

    *** I read the item description: states it's for 200v mains... May want to verify it's intended input voltage before ordering.

    Daytons seem to start at 250v and go up. Shouldn't be a problem

    Sorry lost me. What is for 200v mains?
  • So we've reached the limit of my knowledge regarding this stuff. When it come to what capacitors to buy, I haven't a clue. As in I literally do not know what specifications to look for. I've made it as far as these links:

    http://www.daytonaudio.com/index.php/loudspeaker-components/crossovers-components/capacitors.html/

    https://www.partsconnexion.com/capacitors-film-claritycap-csa-esa-250vdc-series.html

    I've looked into this thread but I'm still not sure what specs I should be looking for this specific capacitor replacement. http://forum.polkaudio.com/discussion/130077/monitor-70-crossover-help-for-noobs-like-me

    Cost is less of a limiting factor than knowledge and skill. I'm not looking to rebuild the crossover, maybe one day when I'm a up to snuff on the technical stuff. For now I'm just looking for what capacitors to purchase so I can try my hand at soldering them bad boys to the boards.

    I do very much appreciate the input thus far. If anyone wants to chime in and give me an exact brand/model capacitor to go after, I'd greatly appreciate the info, I don't know what I don't know here, capacitors and their specifications are like a foreign language to me.
  • FestYboyFestYboy Posts: 3,737
    pitdogg2 wrote: »
    FestYboy wrote: »

    *** I read the item description: states it's for 200v mains... May want to verify it's intended input voltage before ordering.

    Daytons seem to start at 250v and go up. Shouldn't be a problem

    Sorry lost me. What is for 200v mains?

    The solder iron.
  • FestYboyFestYboy Posts: 3,737
    @RandomNonsense the voltage on the cap doesn't matter at this point as long as it matches or exceeds the stock unit at 50v. The important part is the capacitance (measured in uF) so look for a number on the cap followed by uF and that's what you need to match. The cap MUST be non-polarized as well.
  • pitdogg2pitdogg2 Posts: 14,719
    FestYboy wrote: »
    pitdogg2 wrote: »
    FestYboy wrote: »

    *** I read the item description: states it's for 200v mains... May want to verify it's intended input voltage before ordering.

    Daytons seem to start at 250v and go up. Shouldn't be a problem

    Sorry lost me. What is for 200v mains?

    The solder iron.

    In the first top header it states 60 watt 110v.
    But i did see below about 200-240v
    The cord in the picture is 110v for sure. Anything in the 200v+ range I'd certainly call a welder LOL.
  • pitdogg2pitdogg2 Posts: 14,719
    FestYboy wrote: »
    @RandomNonsense the voltage on the cap doesn't matter at this point as long as it matches or exceeds the stock unit at 50v. The important part is the capacitance (measured in uF) so look for a number on the cap followed by uF and that's what you need to match. The cap MUST be non-polarized as well.

    Take a picture of the wording on the caps in question we will help to make sure you get the correct value.
  • Much obliged

    Hard to get all of the info in one picture so two will have to suffice.

    dnrm6lwbr78m.jpg
    1i66sczs9ufv.jpg

    Many thanks to both y'all.
  • FestYboyFestYboy Posts: 3,737
    Looks like 8uF to me.
  • pitdogg2pitdogg2 Posts: 14,719
    Yes i was looking for the schematic to double check couldn't find it.
  • I've come up with a few candidates but would like some verification. I don't have any bias towards the options as I don't really know anything about this stuff.

    The four options I could find, easily are below:

    https://www.partsconnexion.com/CLARITY-82488.html

    http://www.daytonaudio.com/index.php/loudspeaker-components/crossovers-components/capacitors/dmpc-8-2-8-2uf-250v-polypropylene-capacitor.html

    http://www.daytonaudio.com/index.php/loudspeaker-components/crossovers-components/capacitors/pmpc-8-2-8-2uf-250v-precision-audio-capacitor.html

    http://www.soniccraft.com/product_info.php/gen-sonicap-82-uf-200vdc-p-447

    Of the aforementioned options I've come across, none of them are outside my price range by any means. I just need to know if any of them will work and which would work "best".

    Additionally I came across another thread which mentions needing to remove a bypass which I believe is what I have circled in the picture below. Please verify if that is required and/or recommended.

    xtys0ppgfde3.jpg

    Thanks in advance for further feedback.
  • pitdogg2pitdogg2 Posts: 14,719
    edited November 2018
    If it was me it would be between the clarity cap and the Sonicap. The Sonicap might be a little bit smaller I didn't look real close at the size but seeing how it's only 200 volt versus 250 volt it may be a little smaller in diameter. Now that thing you have circled there I believe it's a hundred volt and I'm not quite sure if that 224 is 2.24 or 22.4 picofarads it could also be the tolerance as well. I really wish i could see the schematic. I'm afraid I'm no help here. I defer to @F1nut or @VR3 hopefully they'll chime in. That yellow stuff is glue probably need to score around it to remove.

    The difference between the Daytons is tolerance one is 3% the other 1%. I personally have never used them but have heard both are pretty accurate in their respective tolerances.
  • VR3VR3 Posts: 23,486
    Remove old solder first, apply some heat around the old cap, lifts right off, the rest of the glue pulls off like old chewing gum

    Voltage won't matter to much, big size differences are 620, 400, 250, 100

    If you do not intend to upgrade the whole crossover, I would just find a place that carries everything you need and order from there. Parts express, Dayton

    Madisound clarity cap px

    Parts connexion Mundorf would be a good option

    Sonicraft sonicap

    I would go ahead and change the resistor to, Dayton non inductive, parts express or Mundorf mox, madisound. Mills mrc 50, parts connexion is good but I'm not a fan of the 12 watt mills.
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • pitdogg2pitdogg2 Posts: 14,719
    edited November 2018
    Well thanks Trey but that didnt answer the question.
    The black NP electrolytic's are bad does the orange drop cap need to go? Is it being used as a bypass cap? Since he is going film cap to replace the lytics does the cap in the circle need to go.
  • RandomNonsenseRandomNonsense Posts: 19
    edited November 2018
    So if I understand correctly, circled with blue is the resistor @VR3 suggests replacing as well. For the part circled in red, if I understand correctly it's a bypass. I have no real idea what that means but that's info I've gathered from another thread. Does it need to be replaced/removed?

    a04p5wrpbyin.jpg

    At this point I'm most interested in getting these M 70's working again. It looks like replacing the resistor, if that's what it is, wouldn't be any more difficult than the capacitor. I am learning quite a bit as I go, thanks to these forums and this thread but I am not ready to replace everything on this board... yet. I can definitely spring for and hopefully handle the capacitor and resistor replacement. If the bypass absolutely must come out, I bet I can manage. I just need to know one way or another. If I can slap in the new capacitor and resistor and the speaker will work and parts won't fail I think I'd be happier not having to remove the bypass, seeing as I don't understand what it is and what it does or doesn't do.

    I also have no idea about tolerance and how/why it matters but I assume 1% is a better number than 3% in this regard.

    As usual, thanks for the feedback.
  • VR3VR3 Posts: 23,486
    edited November 2018
    The bypass cap, the one circled would just be removed if you replace the 8uf with a higher quality cap like we are discussing. You can also use 8.2uf as well, that will increase your options.

    Ymmv, as long as it's within 5 percent you will be OK
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • So with an 8.2uf capacitor I have to remove the bypass? If so, do I need to do anything with those solder points or can I just leave them open? As far as the resistor goes, I believe its a 5 watt 1 ohm resistor. Do I need to replace it with one of equal specification?
  • pitdogg2pitdogg2 Posts: 14,719
    The resistor can go up in wattage but keep it at the ohm value. So it can be 10 or 12 watt 1 ohm.
  • VR3VR3 Posts: 23,486
    I would remove the bypass cap regardless
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • pitdogg2pitdogg2 Posts: 14,719
    So with an 8.2uf capacitor I have to remove the bypass? If so, do I need to do anything with those solder points or can I just leave them open? As far as the resistor goes, I believe its a 5 watt 1 ohm resistor. Do I need to replace it with one of equal specification?

    Leave them open.
  • RandomNonsenseRandomNonsense Posts: 19
    edited November 2018
    So it would seem. After doing plenty of reading I believe I somewhat understand the bypass. It seems its a .22 µF ceramic capacitor in parallel with the original 8.0 µF capacitor bringing the total capacitance to 8.22 µF with 5% tolerance. I certainly don't know what all of that means but I have a basic understanding why replacing my blown capacitor with an 8.2 µF capacitor may necessitate the need to remove the bypass. I type may, because if I have this right, the capacitance affects the crossover frequency or something like that. I generally have no idea what I am typing about so who knows. In this particular case my reading and knowledge (or lack thereof) suggest I can remove it or leave it and either way it shouldn't matter. I am curious as to why switching to a film capacitor means I should remove it. Is it that film capacitors are just better or more efficient or something like that?

    Seeing as how I will be attempting to mount the new capacitors and maybe new resistors to the back of the board, what gauge wire should I use to reach the solder points if the leads are not long enough? Also, probably a silly question but will I need to take any extra precaution to insulate the exposed solder points on the back of the board from my replacement parts? Lastly, the do I need to preserve the white case on the resistors and use it with my replacement resistors or can I install the new resistors as they are or will be anyway...?
  • pitdogg2pitdogg2 Posts: 14,719
    They used it to make the Lytic sound better. the lytic could of been off by as much as 10% one way or another. The film cap is 3% and sound better than electrolytic's so no need for a bypass cap.
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