Polk SDA2B "turbulence"

jeff_nh

Hi everyone. I'm new to Polk speakers, recently acquiring a pair of SDA2B. After a day or so of listening, I've observed some issues that I hope those with more experience can comment on.
1) They seem quite bright to me. I've read that replacing the tweeters with the RDO-194 will tame this brightness somewhat. Thoughts?
2) While listening to some newer bass heavy (electronic) music at higher levels, the mid drivers started to "flap" violently during low frequency passages, seemingly exceeding their excursion limits. Has anyone experienced this? Am I simply over-driving them?
The amps I've used are both Carvers, M1.0t (200wpc) and pm1.5 (450wpc). No subwoofer. The room is quite large, speakers about 8' apart, 3-4 feet from one wall and double that length from the other wall.

Thanks.

heiney9

1) yes and you should upgrade all the caps and resistors too.

2) you need more power (you're over driving your amplifier) to listen at that level or lay off the heavy electronic music.

H9

JPete

The tweeter upgrade is a definite improvement over the SL2000s.

I've never bottomed out the midranges on any of the old Polks. Have you checked to make sure there isn't any voice coil rubbing going on? Are the cabinets sealed well?

westmassguy

Welcome to Club Polk. Sounds like you have air leaks, in addition to aging components.
Gently press in and hold the 12" passive radiator. The two woofer should pop out, and stay out for 3-5 seconds and then slowly recede back to their original position. If they pop out and recede quickly, you've got leaks.
The tweeters you have now, are most likely the SL2000 Silver Coils, which are god-awful.
The drop-in replacement is the RD-0194 Silk Dome available from Polk Customer Service.
Alternatively, if you intend to upgrade the crossovers, the 2Bs can be modified for the even better RD-0198-1 Silk Dome Tweeter. Although physically the same size as the 194, the 198 requires a slight modification to the crossover, so it's not a drop-in replacement.
Be sure to tell Customer Service you're a Club Polk Member for the discount and free shipping.
I own the SDA-2As which preceded your 2Bs. Either of those Carver amps should power them just fine, unless you're trying for ear splitting concert levels. You're asking a lot from two 6.5" woofers playing electronic bass tracks.

smglbrth

I’ve bottomed out drivers before on SDA’s. Either get different speakers for your type of listening or turn it down. Echoing what has been said about the 6.5” drivers, you might be asking too much of them.

Welcome to Club Polk!

jeff_nh

Thanks for the Welcomes and the quick replies!
Planning on a tweeter replacement.
The bottoming out happened several hours into the listening session, so it didn't happen with my "typical" music, just with a few songs that were in the mix.

F1nut

You may be happier with some CV's.

xschop

^^^^Good advice^^^^

jeff_nh

Thanks for the replies.
Should probably start a new thread for this but here goes:

Tweeter replacement is either drop-in RD0194-1 or replace original SL2000 with RD0198 and parallel a 5.8uF across a resistor in the x-over.

Preference?

Issues with each:

1) Polk is out-of-stock on the RD0194-1. I'm impatient and think the SL2000 suck. Can't get them out fast enough.

2) I can only find 5.6uF caps (Parts Express)

Thanks.

westmassguy

Are you just adding the shunt cap, or rebuilding the entire crossover?
Sonic Craft has the 5.8 Gen II Sonicraft

gmcman

Along with recapping and using the RDO-198...just curious if you are using a turntable when the woofer cones are 'flapping violently"?

jeff_nh

No turntable. I think I know where you're going with this. In another setup a few months back I hit some type of resonance while running a turntable at high output levels. Scared the crap out of me for a second, then figured it out.
I'm using macbook thru standalone DAC.
I ended up buying the RD0194-1. Polk had them in stock. Very pleasant to deal with, didn't even have to ask for the club polk discount.

Thanks for all the suggestions. I'm going to go thru posts regarding sealing the cabinets. Maybe only about 2 seconds on the leak test.

pitdogg2

Subsonic rumble from turntable makes woofers do all sorts of crazy stuff. Most times it is not audible you just see the woofer acting crazy. It can cause over excursion which can ruin the driver if driven hard.

K_M

JPete wrote: »

The tweeter upgrade is a definite improvement over the SL2000s.

I've never bottomed out the midranges on any of the old Polks. Have you checked to make sure there isn't any voice coil rubbing going on? Are the cabinets sealed well?

Its fairly easy to do, simply play some really loud deep bass.

smglbrth wrote: »

I’ve bottomed out drivers before on SDA’s. Either get different speakers for your type of listening or turn it down. Echoing what has been said about the 6.5” drivers, you might be asking too much of them.

Welcome to Club Polk!

Best thing we did, filter out the deep bass and get 2 large subs.

The 6.5" woofers are fairly easy to bottom out.
They have deep bass, but limited excursion.

nooshinjohn

K_M wrote: »

Best thing we did, filter out the deep bass and get 2 large subs.

The 6.5" woofers are fairly easy to bottom out.
They have deep bass, but limited excursion.

Once again K_M, you do not know what you are talking about with regards to SDA's. They are NOT easy to bottom out. I push my 1.2TL's HARD and have yet to hear anything like what the OP describes.

However, they are really easy to clip when pushed by amplification that is not able to deliver the current needed to drive them, and that is where the damage is done. Based on the scenario described...

jeff_nh wrote: »

No turntable. I think I know where you're going with this. In another setup a few months back I hit some type of resonance while running a turntable at high output levels. Scared the crap out of me for a second, then figured it out.
I'm using macbook thru standalone DAC.
I ended up buying the RD0194-1. Polk had them in stock. Very pleasant to deal with, didn't even have to ask for the club polk discount.

Thanks for all the suggestions. I'm going to go thru posts regarding sealing the cabinets. Maybe only about 2 seconds on the leak test.

I believe the speakers are being driven into a "clipping" scenario by improper amplification. Neither Carver amp listed by the OP are capable of supplying the current needed to control the drivers. It's not about the watts in this case. Both Carver amps are light on current.

F1nut

I've never bottomed out the drivers in my SDA's even at extreme volume levels playing music with deep bass. Proper he-man amplification is the key.

heiney9

I've had my system cranked with proper amplification rattling the windows and never bottomed out a 6.5" driver.

But I don't listen to artificially generated low bass notes or organ music.

It's funny that when Stereo Review did the test review of the 1C's in 1987 they said their amp ran out of power at 400 watts and still the 1C's still hadn't peaked. Meaning they could take more. I realize the 1C's have more drivers. But amplification has a lot to do with this situation.

H9

F1nut

A friend with 2BTL's and a he-man amp has played his rig at extreme volume levels with deep bass for me. The drivers were pumping like crazy, the bass was slamming my chest and they never bottomed out.

K_M

You guys crack me up...!!

If I say the sky is blue you will all chime in and say it is green.

Okay you are all right, a $10.00 6.5" woofer from the 80s is impossible to bottom out. You win.

heiney9

Why can we not relate our experiences just like you? They are very difficult to bottom out unless you are over driving the amplifier.

I sold the damn speakers in the hey day and the only time the drivers were "popping" is when not properly amplified. Back then it was easier to make them pop, as he-man type amps were very expensive. Today a comparable amp to the he-man 80's amps is much less expensive and there are more choices.

Yes, at some point physics comes into play, but that point is far away in my experiences with all Polk MW drivers.

nooshinjohn

K_M wrote: »

You guys crack me up...!!

If I say the sky is blue you will all chime in and say it is green.

Okay you are all right, a $10.00 6.5" woofer from the 80s is impossible to bottom out. You win.

A Polk 6.5, doped paper cone driver from the 1980's is still superior to many more exotic and expensive designs made today. Using proper amplification with HIGH CURRENT to properly control the speaker in both directions of it's travel, and you will very rarely push one to fail. However, if you use poor amplification and one that has low current, you can fry them even at modest volumes.

And to be clear, it is not about watts. I have heard 25 watt high current tube amps push TL's to concert levels with ease, and I have heard 125 watt HT receivers fail miserably. This is why I chose high current-high wattage tube amps to drive my 1.2TL's... best of both worlds.

F1nut

K_M wrote: »

You guys crack me up...!!

If I say the sky is blue you will all chime in and say it is green.

Okay you are all right, a $10.00 6.5" woofer from the 80s is impossible to bottom out. You win.

Looking at your list of power choices I can see why you have bottomed out the drivers.

nooshinjohn

Agreed on that list Jesse. This amplifier, for not a lot of coin, and never again would clipping be a problem...
https://www.audiogon.com/listings/lis9cbbi-threshold-s-300-sii-solid-state

gmcman

K_M wrote: »

You guys crack me up...!!

If I say the sky is blue you will all chime in and say it is green.

Okay you are all right, a $10.00 6.5" woofer from the 80s is impossible to bottom out. You win.

That's not what we are saying or implying.

There's likely something else amiss and in the OP's case, it's possibly an air leak or woofer pumping from a turntable in which the latter was already dismissed.

@jeff_nh , are your 2B's the studio or do they have the wood end caps? If they have the wood end caps, check that the mounting bolts are tight.

nooshinjohn

@GMC.... The OP is using low-current Carver amps that likely need a recap, and even then would be insufficient to drive the speakers he is using. He needs a better amp, but I do agree that going through the speakers at this point, is also a good idea.

K_M

Seriously some of you guys do not understand what you think you do.
Not enough power can generate clipping distortion that generates "high frequency" distortion.
But has nothing to do with a speakers Xmax value or excursion.

Excursion is merely the movement of a woofer, due to increasing volume or current into the driver.

A higher powered amp can push ANY driver past its excursion limit.
The woofers in the vintage Polk speakers were fine for their time, but had limited excursion compared to many more recent ones.

We like the vintage Polks as much as anyone, but they were not somehow defeating the laws of physics, or better than every other woofer made.

Be realistic.

K_M

gmcman wrote: »

K_M wrote: »

You guys crack me up...!!

If I say the sky is blue you will all chime in and say it is green.

Okay you are all right, a $10.00 6.5" woofer from the 80s is impossible to bottom out. You win.

That's not what we are saying or implying.

There's likely something else amiss and in the OP's case, it's possibly an air leak or woofer pumping from a turntable in which the latter was already dismissed.

@jeff_nh , are your 2B's the studio or do they have the wood end caps? If they have the wood end caps, check that the mounting bolts are tight.

Actually some are saying that. Not you.

Yes it could be an air leak, or simply he expects more out of them than they are capable. Loud deep bass, every speaker has a limit.

The vintage Polks are NO different.

nooshinjohn

Perhaps it is you that doesn’t understand. A high current amplifier exerts control over the movement of the cone in both directions. This will stop the movement of the cone before it bottoms out and stops it in the other direction before it extends to far. If the driver is properly controlled throughout its movement, the risk of damage is greatly reduced as volume is increased.

My speakers are rated for 1000 watts, or as little as 20 watts, but without the control provided by the current my amplifiers provide, I would fry them in a nano second. Watts provide volume, current provides the means to control those watts. I think that is what you are failing to grasp.

RobbyKY

OK, I have the exact same set-up as the OP as one of my systems.

As much shade as Carver gets, I've never experience anything like what is being described here with the M1.0T (non-inverting model).

Granted, the 2B's have been given the full Polk upgrade and the Carver has been recapped, metal-filmed and generally upgraded where possible but not MKII modified.

They can rock some serious bass undistorted and my ears give up long before the amp gets into clipping.

Something else is amiss here. Probably time for a crossover rebuild or cabinet sealing project for starters.

codycatalist

K_M wrote: »

Seriously some of you guys do not understand what you think you do.
Not enough power can generate clipping distortion that generates "high frequency" distortion.
But has nothing to do with a speakers Xmax value or excursion.

Excursion is merely the movement of a woofer, due to increasing volume or current into the driver.

A higher powered amp can push ANY driver past its excursion limit.
The woofers in the vintage Polk speakers were fine for their time, but had limited excursion compared to many more recent ones.

We like the vintage Polks as much as anyone, but they were not somehow defeating the laws of physics, or better than every other woofer made.

Be realistic.

So by your statement then it would be impossible to clip a subwoofer amplifier in a car that doesn't have full range frequency. Okay, let me turn my gain all the way up, bass boost all the way up and see how long my subwoofer lasts. A square wave is a square wave. It isn't frequency biased but it does usually hurt tweeters first as high frequencies have a lot of energy. Go ahead and talk your way out of it though.

I only offer my experience. I listen to a LOT of hip-hop and I am somewhat of a bass head (although I try to control myself with my SDAs) and have VARIOUS songs that go down to 25hz. I have played said tracks at high SPL levels without a whimper from my 2Bs.

xschop

^^^^ just need an LOL for a full house ^^^^