10A crossover issue what could I be missing
jpromo134
Posts: 11
Did a simple, no-frills, crossover recap on my 10As. One works great, the other basically has nothing but a tiny bit of sound coming through.
Pulled it apart, checked my work and tested all components. Resistors are reading over 4ohms when they should be 2.5 and 2.7 but this shouldn't cause a complete sound loss. Still not sure why they are so far off after only two heat cycles. I'm experienced at soldering but I've not dealt with crossovers much. Caps tested perfect.
What should I be checking? They were previously working. I don't readily have the schematic but I figured y'all would be familiar with it from the component list. Can add pictures if needed.
Clarity 12uf x 2 (one in parallel with the 2.5)
Solen 33uf x 1
Mills resistors
Thanks!
Pulled it apart, checked my work and tested all components. Resistors are reading over 4ohms when they should be 2.5 and 2.7 but this shouldn't cause a complete sound loss. Still not sure why they are so far off after only two heat cycles. I'm experienced at soldering but I've not dealt with crossovers much. Caps tested perfect.
What should I be checking? They were previously working. I don't readily have the schematic but I figured y'all would be familiar with it from the component list. Can add pictures if needed.
Clarity 12uf x 2 (one in parallel with the 2.5)
Solen 33uf x 1
Mills resistors
Thanks!
Best Answer
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Start with the basics. Swap either the speakers (L&R) or the speaker wires at the amp. Did the issue follow the speaker or stay on the same channel?
Happy Thanksgiving BTW and please allow me to offer you a very warm welcome to Club Polk.
Tom~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~
Answers
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Loose connection?
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skipshot12 wrote: »Loose connection?
No, checked that a couple times on a couple different speaker wires. It is my first thought when sound is faint but not the case this time. -
Just to be clear, before you soldered them in the resistors read 2.5 and 2.7 and now after firing the speakers up and removing them they measure over 4?
With the drivers all connected take DC resistance measurements across the + and - binding posts on both the L and R speakers. What do you get?
Check all MW drivers for voice coil rubbing and make sure there is none and that all drivers cones move freely.Post edited by Gardenstater onGeorge / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
You can't measure a resistor in the circuit.Resistors are reading over 4ohms when they should be 2.5 and 2.7
No sound issue, check the fuse and clean the fuse ends along with the clips.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
You can't measure a resistor in the circuit.Resistors are reading over 4ohms when they should be 2.5 and 2.7
I lifted a leg to check all components. The fuse toned out strong at the clips but it really seems like it had to be a poor contact somewhere.
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Gardenstater wrote: »Just to be clear, before you soldered them in the resistors read 2.5 and 2.7 and now after firing the speakers up and removing them they measure over 4?
I did commit a cardinal sin and did not test all components before assembly, though they were Mills resistors I really expect they were significantly closer than that.
Resistance matched the working speaker--right around 5ohms at the posts for both.
Driver cones are good and not seized.
I think I just need to solder it back together and try again. A bit bummed about the resistor values and I don't have backups...
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Start with the basics. Swap either the speakers (L&R) or the speaker wires at the amp. Did the issue follow the speaker or stay on the same channel?
Happy Thanksgiving BTW and please allow me to offer you a very warm welcome to Club Polk.
Tom
Thanks! Good to be here. I've had these 10s for a number of years but never had to seek help. It definitely followed the speaker. I was actually a/b'ing the recaps against some Bozaks so I had several wires to choose from and known working options at hand to play with. I was really hoping it to be something silly. -
jpromo134 wrote:
It definitely followed the speaker.treitz3 wrote:Start with the basics. Swap either the speakers (L&R) or the speaker wires at the amp. Did the issue follow the speaker or stay on the same channel?jpromo134 wrote:Resistance matched the working speaker--right around 5ohms at the posts for both. Driver cones are good and not seized.
Hmmm, this is strange. If it followed the speaker after the swap? It's an internal issue within the speaker. But then you stated that the resistance within each speaker at the binding posts were the same.
Is a cap installed backwards?
If it's not that, then the only thing I can think of is to disconnect all components and check each one in the bad speaker to make sure they are 1) in tolerance and 2) not open or otherwise bad.
Tom
~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~ -
Since it looks like you've tried/tested several things, I'll throw this out.
When I re-capped my XO's, I ended up lifting a trace (likely when removing the old components) which destroyed a connection. Remember, these boards are old (like decades), so it's easy to damage the traces and vias.
Good luck!Yamaha RX-A2050 AVR (5.0.2); LG OLED77C2 4K TV(4) Polk Monitor 10B's w/SoniCaps, Mills, and RDO-194 tweets (R/L F/R)(2) Polk RC80i (Top Middle)Polk CS300 center channelAnalog: B&O TX2 Turntable, Nakamichi Cassette Deck 1Digital: Pioneer CLD-99 Elite LD, Panasonic DMP-UB900 UHD Blu-RayBedroom: Arylic Up2Stream AMPv3 driving Polk Monitor 4's w/peerless tweets -
Since it looks like you've tried/tested several things, I'll throw this out.
When I re-capped my XO's, I ended up lifting a trace (likely when removing the old components) which destroyed a connection. Remember, these boards are old (like decades), so it's easy to damage the traces and vias.
Good luck!
The old circular boards have heavy duty large pads, they have no traces. If this is a different board it could be a possibility.
What caps did you use film or non-polar electrolytic?
A 10a is a pretty simple XO pull all off bad side test and resolder. -
Thanks for the comments y'all. I have found my issue and it was stupid (I'm pleased). I had tried both A+B configurations on my receiver but hadn't flipped L+R... I put it all back together and toggled reverse and it came alive leaving the other side dead. Seems my tuner was just a nip off and was cutting out the left channel. I had other speakers set up but it must have been going in and out because those were testing fine on tuner.
So I verified with phono and it's fine. So here's your friendly reminder to check multiple inputs. Thanks for all the help! -
Start with the basics. Swap either the speakers (L&R) or the speaker wires at the amp. Did the issue follow the speaker or stay on the same channel?
Happy Thanksgiving BTW and please allow me to offer you a very warm welcome to Club Polk.
Tom
So I had not flip L+R, only switched between A+B on my amp. After reversing L+R, I found the issue was just a danged input problem from my tuner cutting out the right channel. I was sure the receiver wasn't the issue. -
That's cool. Congrats on fixing. What about your 4+ ohm resistors?George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Something smells funny.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
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Gardenstater wrote: »That's cool. Congrats on fixing. What about your 4+ ohm resistors?
They were reinstalled for the time being as I don't have any extras. Of course the price has doubled since July so replacing those two resistors prices out around 20$ after shipping
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So I had not flip L+R, only switched between A+B on my amp. After reversing L+R, I found the issue was just a danged input problem from my tuner cutting out the right channel. I was sure the receiver wasn't the issue.
Ah, that makes MUCH more sense! A bit of friendly advice? Always start with the basics when troubleshooting and never assume. Always verify.
Sorry to hear that another component has been compromised but glad that you have at least identified the issue. Now you know what to work on. 😉
Tom
~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~ -
I've never had a Mills resistor that wasn't spot on the money.
The result of 4 ohm resistors in place of the 2.5 and 2.7 will be extremely muted sound.
Like I said, something smells funny.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I've never had a Mills resistor that wasn't spot on the money.
The result of 4 ohm resistors in place of the 2.5 and 2.7 will be extremely muted sound.
Like I said, something smells funny.
I think it has to be from when I took them apart to test everything. Those large pads soak up a lot of solder, so removal takes some heat and multiple passes on the suction. Heat is the only reason I can justify it. Markings signified correct values. The originals read 3.2 and 3.5 respectively so those were even closer. -
I hope you didn't order Run Of The *Mills* by mistake 🤣
This is definitely unusual. A wirewound resistor that had its resistance go up permanently from heat........
Meter calibration/error issues have been ruled out? Fresh battery in the meter?George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I've never had a Mills resistor that wasn't spot on the money.
The result of 4 ohm resistors in place of the 2.5 and 2.7 will be extremely muted sound.
Like I said, something smells funny.
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Your resistors should be within a 1% tolerance. If you truly measured just the resistor and nothing else in the circuit, then the resistor has been permanently compromised.
When doing point to point wiring, you want to make a mechanical connection first, followed by a quick but thorough electrical connection (using the solder). Also, make sure that the connection point isn't slammed right up to the edge of the resistor housing itself.
Tom~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~ -
Tom makes an excellent point, never bend the resistor lead right where it comes out of the body. I use needlenose pliers to hold the lead at the body and create the bend after.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Tom makes an excellent point, never bend the resistor lead right where it comes out of the body. I use needlenose pliers to hold the lead at the body and create the bend after.
This is common practice for me as well. The electrical connections on my 2.5 were fairly close to the body because of the close thru-holes, though no bends were right at the body. The 2.7 running so high makes no sense as those leads were still very long. I ordered replacements and will triple check these when I get back in there. -
Your resistors should be within a 1% tolerance. If you truly measured just the resistor and nothing else in the circuit, then the resistor has been permanently compromised.
When doing point to point wiring, you want to make a mechanical connection first, followed by a quick but thorough electrical connection (using the solder). Also, make sure that the connection point isn't slammed right up to the edge of the resistor housing itself.
Tom
Yes, I lifted a leg to test both resistors and they were absolutely well out of tolerance. My technique is exactly as you describe, twist around the parallel cap or bend the leads on a thru-hole first, then proper heating to apply solder.
I am chalking it up to a fluke. Been doing this stuff for years and never had anything fly out of tolerance like this though. Thanks for all the helpful comments. -
Since it looks like you've tried/tested several things, I'll throw this out.
When I re-capped my XO's, I ended up lifting a trace (likely when removing the old components) which destroyed a connection. Remember, these boards are old (like decades), so it's easy to damage the traces and vias.
Good luck!
The old circular boards have heavy duty large pads, they have no traces. If this is a different board it could be a possibility.
What caps did you use film or non-polar electrolytic?
A 10a is a pretty simple XO pull all off bad side test and resolder.
I used the (good) film ones; I think they've like doubled in price since I did my XO.
One of those large pads came off when I was removing an (old) part.Yamaha RX-A2050 AVR (5.0.2); LG OLED77C2 4K TV(4) Polk Monitor 10B's w/SoniCaps, Mills, and RDO-194 tweets (R/L F/R)(2) Polk RC80i (Top Middle)Polk CS300 center channelAnalog: B&O TX2 Turntable, Nakamichi Cassette Deck 1Digital: Pioneer CLD-99 Elite LD, Panasonic DMP-UB900 UHD Blu-RayBedroom: Arylic Up2Stream AMPv3 driving Polk Monitor 4's w/peerless tweets
