Polk and kenwood problem

[Declan WS]

Hey everybody, so I’ve got a rather strange problem and I’m not sure if it’s a speaker problem or an integrated amp problem.

The setup
I’ve got a beautiful pair of Polk SRS SDA 3.1s (with the SDA cord connecting them), a Kenwood KA-3500 integrated amplifier powering them, and a kenwood ss-79 surround sound processor with two rear Polk speakers.

The problem
My primary Polk SDA’s are working strangely. The right has a lot of clarity and detail but very little bass, while the left is a bit muffled with lots of bass.
With music I can balance it a bit more to the left and it kind of fixes it, but I’m still losing detail. And with television (for whatever reason) it leads to the background music only really coming from the left speakers.

Notes
• I have a fairly small room, so the right speaker is (unfortunately) pressed right up against the wall, while the left is not.
• there’s a slight hum constantly being generated that I cannot fix, whether I unplug everything or not.
• I’m plugged into the B setting on the Kenwood.
• I have a record player and an Xbox plugged into the system, the issue persists with both.
• I don’t think this was an issue before I changed from a kinda iffy surround sound receiver to the Kenwood and I’d change back but the kenwood offers a way nicer sound despite only generating 50 watts per channel.
• the issue continues with the surround sound processor unplugged.
• I’ve double checked the polarity of the speaker wire and I’ve recut the left speaker wire to combat dust buildup.

Any ideas I’m happy to hear, I’ve opened up a kenwood before so if that’s a must, just let me know, and I do have a guy for speaker repair, these things are just huge and he’s busy a lot. Thanks!

 

[Dswankey]

Hey everybody, so I’ve got a rather strange problem and I’m not sure if it’s a speaker problem or an integrated amp problem.

The setup
I’ve got a beautiful pair of Polk SRS SDA 3.1s (with the SDA cord connecting them), a Kenwood KA-3500 integrated amplifier powering them, and a kenwood ss-79 surround sound processor with two rear Polk speakers.

The first thing that jumped to mind is that your amp is woefully under powered for the SDA's let alone the additional speakers.

The SDA's need a lot of power to really shine and your current 40wpc is not doing them any justice.



https://www.hifiengine.com/manual_library/kenwood/ka-3500.shtml



Whether this is causing your issues I'll let other more knowledgeable chime in

 

[Dswankey]

.... My primary Polk SDA’s are working strangely. The right has a lot of clarity and detail but very little bass, while the left is a bit muffled with lots of bass.

• there’s a slight hum constantly being generated that I cannot fix, whether I unplug everything or not.

I would also check to make sure each SDA speakers components are working correctly also what are the other Polk speakers you have connected as rears?

 

[Hoytis]

I have a KA-3500...that's just too much for that amp...not to mention it's 40 watts, not 50. You need a different amp, preferably more of an A/V amp if you're into running TV/Xbox etc through it.

 

[Declan WS]

I would also check to make sure each SDA speakers components are working correctly also what are the other Polk speakers you have connected as rears?

Couldn’t tell you off the top of my head, but the issue persists with or without them.

 

[Declan WS]

I have a KA-3500...that's just too much for that amp...not to mention it's 40 watts, not 50. You need a different amp, preferably more of an A/V amp if you're into running TV/Xbox etc through it.

Yeah, I figured that may be it. I’m trying to get an EAD ovation to have that nice balance for quality of music and television, but they’re really hard to find. Any idea why the amp may be causing this specific problem?

 

[percivilla]

Start simple. Put the amp in mono, speakers still unbalanced? Then the issue is likely the speakers. Try switching cables left to right, problems persists? definitely speakers.

 

[Hoytis]

Yeah, I figured that may be it. I’m trying to get an EAD ovation to have that nice balance for quality of music and television, but they’re really hard to find. Any idea why the amp may be causing this specific problem?

Other than that amp being over 40 years old? I would be focused on the hum and getting rid of it. I'd be surprised if your speakers are at fault (especially since you said you didn't notice anything wrong with the other amp). You may have a ground loop happening somewhere. The KA3500 is old and can be finicky. You might just need to take it in for tune up.

Break it all down, forget the surrounds, and just plug in the main speakers (try system A) and one source, like your turntable. If the issue happens right off the bat with just two speakers and a turntable, do what percivilla said and reverse the speaker cables...does the problem follow? If yes, the amp is the issue. If not, then the speakers are at fault.

 

[Declan WS]

Start simple. Put the amp in mono, speakers still unbalanced? Then the issue is likely the speakers. Try switching cables left to right, problems persists? definitely speakers.

Good idea, I’ll try that once I get home. That said, I’m not sure how to put my amp in mono other than playing a mono song/record. Can the kenwood do that?

 

[percivilla]

Good idea, I’ll try that once I get home. That said, I’m not sure how to put my amp in mono other than playing a mono song/record. Can the kenwood do that?

Just checked a picture on the great Google, guess it doesn't have mono. No problem, the first thing you want to do is eliminate simple things. Try reversing right and left on the RCA's and see what happens? Try swapping speaker cables left to right and vice versa and see what happens? Fiddle with knobs and switches and see if anything happens etc. Sounds like you have other speakers. Hook them up and see what happens. No sense digging into the amp if the problem is elsewhere.

If none of those easy checks yield results, the next step is to crack it open and take de-oxit or contact cleaner to the controls. Dirty pots and switches can do some really strange things. Only once the all the controls are thoroughly and properly cleaned will you know for sure that there is an actual fault with the amp.

 

[Schurkey]

I’ve got a beautiful pair of Polk SRS SDA 3.1s (with the SDA cord connecting them), a Kenwood KA-3500 integrated amplifier powering them, and a kenwood ss-79 surround sound processor with two rear Polk speakers.

The Kenny is probably common-ground...however, it wouldn't hurt to connect an ohmmeter on "Low(est) Ohms" scale across the negative speaker output terminals of the two channels. Disconnect the speaker cables first. Anything over 1 ohm is a problem; less is better. Ideal is "zero" resistance between the two negative speaker terminals.

[Edit] The "B" speaker output seems to be common-ground for the purposes of the SDA speakers, according to the schematic--the "A" speaker outputs? Got me. I can't follow the traces.[/Edit]

No ohmmeter? Unplug the SDA connecting cable from one of the speakers. Doesn't matter which one. If the sound clears-up, you've likely got common-ground issues. The Polk SDA series is VERY sensitive to non-common-ground amplifiers.

My primary Polk SDA’s are working strangely. The right has a lot of clarity and detail but very little bass, while the left is a bit muffled with lots of bass.

Left speaker has a failed tweeter or loose jumper wire on the dual binding posts at the rear of the speaker cabinet? Grab a cardboard core from a roll of paper towels, put your ear to one end, and the tweeter near--but not touching--the other end. Try both speakers. If you hear one tweeter through the cardboard tube but not the other you can be sure there's a problem SOMEWHERE in the tweeter circuit. There's NO protection devices in the crossover for the single tweeter per cabinet. Therefore, the tweeters get worked hard, and a low-power amplifier is likely to pop the voice coil when the amp clips. Replacement tweeters are sort-of available from Polk. Call Polk Customer Service, and tell them you need two RDO-198-1 tweeters. Sometimes they have stock, sometimes not. Replace both if one is bad; the new tweeters are an upgrade from the originals. Heck, replace both tweeters even if they both work (assuming you can get them.)

Several possibilities for the lack of bass in the right speaker:
These speakers need to be "air tight". Push the bassive radiator "in" a half-inch, the midwoofers should pop "out". See how long it takes for them to recede to where they were. When you let go of the bassive radiator, the midwoofer cones should "suck in". Again, they'll return to a neutral position, but it should take a couple of seconds. If they recede too quickly, the cabinet has air leaks that will destroy bass output. Compare the time it takes the drivers to return to neutral position with the speaker cabinet that has "good" bass.

Push gently on each mid-woofer. They should move silently and smoothly--no "scratchy" feeling, and certainly not "locked-up". If one or more is scratchy or immobile, you'll need to either replace the driver, or have it repaired.

Make ABSOLUTELY CERTAIN that both speakers are wired in-phase and "correct". The + outputs of the amplifier must be connected to the + terminals of the speakers--and there have been cases of the + (red) and - (black) plastic nuts on the equipment being installed wrong.

• I have a fairly small room, so the right speaker is (unfortunately) pressed right up against the wall, while the left is not.

Absolutely not optimum--Polk says you should have "at least" three feet to the side of each speaker. However, that shouldn't cause a "weak bass" problem.

• there’s a slight hum constantly being generated that I cannot fix, whether I unplug everything or not.

Hum at the equipment/amplifier; or hum coming through the speaker drivers? BIG difference in diagnostics.

• I don’t think this was an issue before I changed from a kinda iffy surround sound receiver to the Kenwood and I’d change back but the kenwood offers a way nicer sound despite only generating 50 watts per channel.

Even more reason to verify that Kenny is common-ground, and that all the + terminals on the amp and speakers really are "+".

I do have a guy for speaker repair, these things are just huge and he’s busy a lot.

IF (big IF) you're not into D-I-Y, get some time scheduled with him to replace the electrolytic (and one Mylar per crossover) capacitors in the crossover network of the Polks. Most folks replace the resistors, too. Some replace the "big" inductor for more bass; a very few replace all the inductors. Pull the cabinet stuffing back up into place, it sags down by the bassive radiator over time. Some damping material on the midwoofer driver baskets improves clarity. Polk assembled the midwoofers by gluing the magnets to the steel baskets; this glue deteriorates over time. Many Polk owners put a ring of epoxy around the magnet-to-basket fillet, and the magnet-to-pole piece fillet.

Those speakers will be OUTSTANDING when given some attention, and better power.

 

[Declan WS]

The Kenny is probably common-ground...however, it wouldn't hurt to connect an ohmmeter on "Low(est) Ohms" scale across the negative speaker output terminals of the two channels. Disconnect the speaker cables first. Anything over 1 ohm is a problem; less is better. Ideal is "zero" resistance between the two negative speaker terminals.

[Edit] The "B" speaker output seems to be common-ground for the purposes of the SDA speakers, according to the schematic--the "A" speaker outputs? Got me. I can't follow the traces.[/Edit]

No ohmmeter? Unplug the SDA connecting cable from one of the speakers. Doesn't matter which one. If the sound clears-up, you've likely got common-ground issues. The Polk SDA series is VERY sensitive to non-common-ground amplifiers.



Left speaker has a failed tweeter or loose jumper wire on the dual binding posts at the rear of the speaker cabinet? Grab a cardboard core from a roll of paper towels, put your ear to one end, and the tweeter near--but not touching--the other end. Try both speakers. If you hear one tweeter through the cardboard tube but not the other you can be sure there's a problem SOMEWHERE in the tweeter circuit. There's NO protection devices in the crossover for the single tweeter per cabinet. Therefore, the tweeters get worked hard, and a low-power amplifier is likely to pop the voice coil when the amp clips. Replacement tweeters are sort-of available from Polk. Call Polk Customer Service, and tell them you need two RDO-198-1 tweeters. Sometimes they have stock, sometimes not. Replace both if one is bad; the new tweeters are an upgrade from the originals. Heck, replace both tweeters even if they both work (assuming you can get them.)

Several possibilities for the lack of bass in the right speaker:
These speakers need to be "air tight". Push the bassive radiator "in" a half-inch, the midwoofers should pop "out". See how long it takes for them to recede to where they were. When you let go of the bassive radiator, the midwoofer cones should "suck in". Again, they'll return to a neutral position, but it should take a couple of seconds. If they recede too quickly, the cabinet has air leaks that will destroy bass output. Compare the time it takes the drivers to return to neutral position with the speaker cabinet that has "good" bass.

Push gently on each mid-woofer. They should move silently and smoothly--no "scratchy" feeling, and certainly not "locked-up". If one or more is scratchy or immobile, you'll need to either replace the driver, or have it repaired.

Make ABSOLUTELY CERTAIN that both speakers are wired in-phase and "correct". The + outputs of the amplifier must be connected to the + terminals of the speakers--and there have been cases of the + (red) and - (black) plastic nuts on the equipment being installed wrong.


Absolutely not optimum--Polk says you should have "at least" three feet to the side of each speaker. However, that shouldn't cause a "weak bass" problem.


Hum at the equipment/amplifier; or hum coming through the speaker drivers? BIG difference in diagnostics.


Even more reason to verify that Kenny is common-ground, and that all the + terminals on the amp and speakers really are "+".


IF (big IF) you're not into D-I-Y, get some time scheduled with him to replace the electrolytic (and one Mylar per crossover) capacitors in the crossover network of the Polks. Most folks replace the resistors, too. Some replace the "big" inductor for more bass; a very few replace all the inductors. Pull the cabinet stuffing back up into place, it sags down by the bassive radiator over time. Some damping material on the midwoofer driver baskets improves clarity. Polk assembled the midwoofers by gluing the magnets to the steel baskets; this glue deteriorates over time. Many Polk owners put a ring of epoxy around the magnet-to-basket fillet, and the magnet-to-pole piece fillet.

Those speakers will be OUTSTANDING when given some attention, and better power.

Holy cow, I’ve never seen anyone answer a question as clearly and efficiently. Thank you so much, I will try as many of those and the other fixes you folks have suggested.

 

[Declan WS]

The Kenny is probably common-ground...however, it wouldn't hurt to connect an ohmmeter on "Low(est) Ohms" scale across the negative speaker output terminals of the two channels. Disconnect the speaker cables first. Anything over 1 ohm is a problem; less is better. Ideal is "zero" resistance between the two negative speaker terminals.

[Edit] The "B" speaker output seems to be common-ground for the purposes of the SDA speakers, according to the schematic--the "A" speaker outputs? Got me. I can't follow the traces.[/Edit]

No ohmmeter? Unplug the SDA connecting cable from one of the speakers. Doesn't matter which one. If the sound clears-up, you've likely got common-ground issues. The Polk SDA series is VERY sensitive to non-common-ground amplifiers.



Left speaker has a failed tweeter or loose jumper wire on the dual binding posts at the rear of the speaker cabinet? Grab a cardboard core from a roll of paper towels, put your ear to one end, and the tweeter near--but not touching--the other end. Try both speakers. If you hear one tweeter through the cardboard tube but not the other you can be sure there's a problem SOMEWHERE in the tweeter circuit. There's NO protection devices in the crossover for the single tweeter per cabinet. Therefore, the tweeters get worked hard, and a low-power amplifier is likely to pop the voice coil when the amp clips. Replacement tweeters are sort-of available from Polk. Call Polk Customer Service, and tell them you need two RDO-198-1 tweeters. Sometimes they have stock, sometimes not. Replace both if one is bad; the new tweeters are an upgrade from the originals. Heck, replace both tweeters even if they both work (assuming you can get them.)

Several possibilities for the lack of bass in the right speaker:
These speakers need to be "air tight". Push the bassive radiator "in" a half-inch, the midwoofers should pop "out". See how long it takes for them to recede to where they were. When you let go of the bassive radiator, the midwoofer cones should "suck in". Again, they'll return to a neutral position, but it should take a couple of seconds. If they recede too quickly, the cabinet has air leaks that will destroy bass output. Compare the time it takes the drivers to return to neutral position with the speaker cabinet that has "good" bass.

Push gently on each mid-woofer. They should move silently and smoothly--no "scratchy" feeling, and certainly not "locked-up". If one or more is scratchy or immobile, you'll need to either replace the driver, or have it repaired.

Make ABSOLUTELY CERTAIN that both speakers are wired in-phase and "correct". The + outputs of the amplifier must be connected to the + terminals of the speakers--and there have been cases of the + (red) and - (black) plastic nuts on the equipment being installed wrong.


Absolutely not optimum--Polk says you should have "at least" three feet to the side of each speaker. However, that shouldn't cause a "weak bass" problem.


Hum at the equipment/amplifier; or hum coming through the speaker drivers? BIG difference in diagnostics.


Even more reason to verify that Kenny is common-ground, and that all the + terminals on the amp and speakers really are "+".


IF (big IF) you're not into D-I-Y, get some time scheduled with him to replace the electrolytic (and one Mylar per crossover) capacitors in the crossover network of the Polks. Most folks replace the resistors, too. Some replace the "big" inductor for more bass; a very few replace all the inductors. Pull the cabinet stuffing back up into place, it sags down by the bassive radiator over time. Some damping material on the midwoofer driver baskets improves clarity. Polk assembled the midwoofers by gluing the magnets to the steel baskets; this glue deteriorates over time. Many Polk owners put a ring of epoxy around the magnet-to-basket fillet, and the magnet-to-pole piece fillet.

Those speakers will be OUTSTANDING when given some attention, and better power.

Also to answer your earlier question, the hum is coming from the speakers and did not occur with the AV receiver. Unplugging the SDA did not change that.

 

[KentTeffeteller]

I have a KA-3500...that's just too much for that amp...not to mention it's 40 watts, not 50. You need a different amp, preferably more of an A/V amp if you're into running TV/Xbox etc through it.

No, you need triple that 50 watts, or more, into a demanding, high current load. No A/V unit short of high $$$ separates will drive that any length of time well.

 

[Declan WS]

Hey everybody, so I’ve got a rather strange problem and I’m not sure if it’s a speaker problem or an integrated amp problem.

The setup
I’ve got a beautiful pair of Polk SRS SDA 3.1s (with the SDA cord connecting them), a Kenwood KA-3500 integrated amplifier powering them, and a kenwood ss-79 surround sound processor with two rear Polk speakers.

The problem
My primary Polk SDA’s are working strangely. The right has a lot of clarity and detail but very little bass, while the left is a bit muffled with lots of bass.
With music I can balance it a bit more to the left and it kind of fixes it, but I’m still losing detail. And with television (for whatever reason) it leads to the background music only really coming from the left speakers.

Notes
• I have a fairly small room, so the right speaker is (unfortunately) pressed right up against the wall, while the left is not.
• there’s a slight hum constantly being generated that I cannot fix, whether I unplug everything or not.
• I’m plugged into the B setting on the Kenwood.
• I have a record player and an Xbox plugged into the system, the issue persists with both.
• I don’t think this was an issue before I changed from a kinda iffy surround sound receiver to the Kenwood and I’d change back but the kenwood offers a way nicer sound despite only generating 50 watts per channel.
• the issue continues with the surround sound processor unplugged.
• I’ve double checked the polarity of the speaker wire and I’ve recut the left speaker wire to combat dust buildup.

Any ideas I’m happy to hear, I’ve opened up a kenwood before so if that’s a must, just let me know, and I do have a guy for speaker repair, these things are just huge and he’s busy a lot. Thanks!

UPDATE: Through all of your guys’ collective knowledge, I think I’ve discovered the problem really is just the amp. I switched the speaker wire so the left was coming out of the right and the right out of the left and the problems swapped sides. Still no fix for the hum, but I believe a new pre amp is in order. Gonna pair it with some high end monarchys. Thank you all so much for your help. And please keep adding onto this thread with any ideas and general related knowledge. I’ll update you all again once I’ve gotten some new parts. Special thanks to Schurkey, I’m definitely getting those new tweeters and doing all your tests to be double certain.

 

[Schurkey]

UPDATE: Through all of your guys’ collective knowledge, I think I’ve discovered the problem really is just the amp. I switched the speaker wire so the left was coming out of the right and the right out of the left and the problems swapped sides.

You needed a different amp/preamp anyway...

The SRS 3.1s are a nominal "6-ohm" speaker; supposedly easy to drive aside from needing additional amperage compared to an "8-ohm" speaker system. But some of the recommended modifications to the crossovers and inductors will reduce the impedance below the "stock" rating; so buy an amp that's rated for 4-ohm speakers (or less than 4-ohm).

Still no fix for the hum, but I believe a new pre amp is in order. Gonna pair it with some high end monarchys.

"Some" "Monarchys"? As in Monarchy power amps, plural?

Separate amplifiers are not, by definition, common ground. There are multiple work-arounds for this; and you'll need to pick one because your speakers will be VERY unhappy with non-common-ground amplifiers. Might even blow-up the amps.

MY amp of choice is partial-non-common-ground; a jumper wire between the negative terminals makes it fully common-ground so it works well with my SDA 1Bs. Not all amplifiers can be jumpered without blowing up--they cannot be "Bridged" or "Balanced" designs. If you have Bridged or Balanced amplifier(s), you can build an isolation transformer that goes into the SDA interconnect cable. Your SRS 3.1s are compatible with that device, my 1Bs are not. Once you have the isolation transformer in place, the speakers will happily accept Bridged/Balanced/Non-Common-Ground amplifiers.

Special thanks to Schurkey, I’m definitely getting those new tweeters and doing all your tests to be double certain.

You need to be on the Polk forums; all your upgrade info is hosted there in the "Vintage Speakers" section, along with speaker crossover schematics and more. Once you're a member of that forum, you get a discount on the tweeters as well.

https://forum.polkaudio.com/categories/vintage-speakers

 

[Declan WS]

I will join that forum! I’ll also talk to my guy about the feasibility of making those modifications/isolation transformer. That said, perhaps I’ll consider a different common ground amp. Any high quality but not ungodly expensive recommendations?

 

[Schurkey]

Until the Big amps are back in service, I'm running my 1Bs off of an Acurus 200X3. My 1Bs were considered "4-ohm" nominal when new, but they've been modified. The changes would tend to lower the impedance somewhat. Once I get the main amps online again, the Acurus may be unemployed.