Recent Polk 705/707 discounts a result of poor design?

pawelmwo

Came across a post on audioholics from a speaker designer that the reason for the recent massive discounts of the Polk 705/707 LSiM line is the result of a major design flaw. That is placing two crossovers below 400Hz at 100Hz and 300Hz stressing avr's and requiring large amounts of amplification, possibly leading to component failure. Is it really an engineering feat or is there some truth to this? I'm new to high fi audio so thought I would post this here and some brighter minds can help shine some light on this.


Quoting:

"You need to drop these speakers like a hot potato. The whole design concept is flawed and insane.

Now we have a lunatic who has presented a speaker with not just one crossover below 400 Hz but two. (100 Hz and 300 Hz)

Now I have designed speakers for years. I can tell you that there is no way you can make a safe speaker like that, let alone a decent one, with a passive crossover solution. I say that categorically, there is no way. I have to work with the same laws of nature as Polk. To even consider this, which is a bad idea anyway as the crossover points are too close together, you would need at least three amps with active crossovers.

Inevitably the stress on the receiver or power amp are going to be horrendous with passive crossovers with those specs.

There is a very high probability the crossover is actually in resonance, a very bad situation for amps driving them. However if you cobble together a contraption like that, you will be far too stupid to spot a detail like resonance.

Do not connect your receiver to a speaker like that. It will vastly shorten its life, if it has not already.

The cynic in me leaves to believe that now Polk and Denon Marantz are the same company, they are deliberately trying to boost the market for replacement receivers.

The is the most egregious concept for a speaker I have seen to date."

URL:

https://forums.audioholics.com/forums/threads/need-help-with-polk-lsim-705-and-yamaha-rx-2030.115444/

ZLTFUL

Whoever posted that is an idiot.

For example, the 705 has *2* crossover points...

CROSSOVER
TypeOrth Crossover Design
Midrange/Woofer Crossover Frequency100 Hz
Tweeter/Midrange Crossover Frequency2800 Hz

The woofers handle below 100hz. The mids between 100-2800hz and the tweeters above 2800hz.

Obviously, there is some crossover point for the mid-woofer to the mid-range driver but 3 way and 4 way crossovers have been around for decades. And I am pretty sure Scott Orth, the namesake of the "Orth" crossover design used in the LSiM series who holds a degree in Acoustical Engineering knows WAY more than the dunder-head who claims to have designed speakers "for years".

Also, Polk is clearing out the LSiM line as it is a direct competitor to what they want the Legend series to be. It isn't because of a design flaw.

F1nut

The tlsguy has no idea what he's talking about, none. Even says they aren't 4 ohm loads when in fact they are. BOZO!!!

DaveHo

I've seen some of the nonsense he's posted over the years, he's an idiot. That said, IMHO the xover freq from MW to the Cassini drivers is too low. I run them full range for music & am always concerned about bottoming out the MW. Enough so that I feel it's holding back what the speaker should be capable of.

Emlyn

I would not drive a pair of 707s with a receiver unless it was 4 ohm stable anyway. That would be insane and horrendous at high volume.

Even if the receiver is stable a high current separate amp is recommended. Those speakers were not designed to be run by lightweights, and neither is the new Legend line. A Parasound A23 handles the LSiM line just fine without any unusual heat buildup, although they sound better with an A21.

VR3

Lol...

msg

Wow, that guy sure is talented with hyperbole. I wonder if he practiced reciting that in the mirror before posting.

mrloren

Wow!

That was a strange read. Polk made the LSiM line for what 9 years? They sold a lot of them over that time, figure there would be many reports on them if they were bad and cooking AVR's.

One thing I read in that thread is the OP was bi-amping with an AVR, oops. Yeah and wondered why they sounded bad.

I like my 705's, sound great and have a decent amp powering them.

Muchieman

Seriously? Guy’s, AH has a lot of Dealers that hang out on that forum. Most of them won’t even recommend Polk speakers. But yet they’ll surely Chastise anyone that does. There seems to be a hand full that stick together.

pitdogg2

Muchieman wrote: »

Seriously? Guy’s, AH has a lot of Dealers that hang out on that forum. Most of them won’t even recommend Polk speakers. But yet they’ll surely Chastise anyone that does. There seems to be a hand full that stick together.

I actually find most "dealers" will recommend lines that are more profitable to them.

mrloren

Muchieman wrote: »

Seriously? Guy’s, AH has a lot of Dealers that hang out on that forum. Most of them won’t even recommend Polk speakers. But yet they’ll surely Chastise anyone that does. There seems to be a hand full that stick together.

True it is AH after all. Most people there hate Polk for some reason.

I was reading a thread where this guy was bragging about having over $20k into his system and only spent $200 on interconnects and speaker wire. Gee wonder how it would sound if he spent a few bucks on some AQ or BJC.

There was this video from Gene where he was saying all anyone needs is Monoprice cable. Then he pulls out a Pair of Kimber cable the run about $900 a pair.

When we use to have retail stores I'd go in for a listen. Most of the time sales people would bash Polk, I'd ask why. Almost every time I got a blank look.

To bash the LSiM like this, a line that sold for years is just obnoxious to say the least. I could see if it was a new line but one that has been out for years. Nope that guy got his little bit of compensation for his little under sized body part (brain that is).

Muchieman

pitdogg2 wrote: »

Muchieman wrote: »

Seriously? Guy’s, AH has a lot of Dealers that hang out on that forum. Most of them won’t even recommend Polk speakers. But yet they’ll surely Chastise anyone that does. There seems to be a hand full that stick together.

I actually find most "dealers" will recommend lines that is more profitable to them.

Well said, it is why I posted up. I just find that the person that said Polk's LSiM line on AH forum would say Polk put out a design a FlagShip line with a flawed design. Polk’s LSiM line has a proven record of Excellent reviews with Pro testing not to mention a lot of very happy customers. If my apartment was bigger I’d surely have a pair of the 705’s sitting in my living room.

mpitogo

I chimed in. Not sure it will help much but someones gotta represent.

vmaxer

mpitogo wrote: »

I chimed in. Not sure it will help much but someones gotta represent.

I had to go read the thread, glad I’m not a member there.

(That I remember)

K_M

mrloren wrote: »

Muchieman wrote: »

Seriously? Guy’s, AH has a lot of Dealers that hang out on that forum. Most of them won’t even recommend Polk speakers. But yet they’ll surely Chastise anyone that does. There seems to be a hand full that stick together.

True it is AH after all. Most people there hate Polk for some reason.

I was reading a thread where this guy was bragging about having over $20k into his system and only spent $200 on interconnects and speaker wire. Gee wonder how it would sound if he spent a few bucks on some AQ or BJC.

There was this video from Gene where he was saying all anyone needs is Monoprice cable. Then he pulls out a Pair of Kimber cable the run about $900 a pair.

When we use to have retail stores I'd go in for a listen. Most of the time sales people would bash Polk, I'd ask why. Almost every time I got a blank look.

To bash the LSiM like this, a line that sold for years is just obnoxious to say the least. I could see if it was a new line but one that has been out for years. Nope that guy got his little bit of compensation for his little under sized body part (brain that is).

Stereophile gave a fairly bad review to the Rta11t's years ago, and was not Sold on the SDA effect at all.

That may play into it, to some degree.