Stereophile reviews the Polk Legend L100

TopperDude

"More than once while listening, I uttered "wow," impressed by the scale of the music they presented"

https://www.stereophile.com/content/polk-legend-l100-loudspeaker

Joey_V

Yeah. I gotta hear one

Borborygmous

I'm planning to buy a Polk Legend L100 for myself too. Can't wait to hear it.

Hansvelton

Sounds like they will sound quite good.

The only things that somewhat bother me, is if they have 40 engineers at Polk, designing speakers, drivers and crossovers, why would they allow such a prominent midrange peak to emanate from the port, let alone the impedance dips in the midrange seem a bit severe, when figuring impedance and phase angles.

"The L100 has minimum EPDRs of 1.73 ohms between 127Hz and 140Hz and 1.25 ohms between 3.3kHz and 3.6kHz."

[Deleted User]

I'll ask them.

Hansvelton

KennethSwauger wrote: »

I'll ask them.

Thank you! Would be curious to hear the reason.
I am assuming you are not being sarcastic.

I would assume some mild series resistance on the tweeter would raise the impedance between 3.3 and 3.6 kHz a bit higher, but not sure what their goal or reasoning was.

[Deleted User]

No sarcasm.

mhardy6647

Hansvelton wrote: »

KennethSwauger wrote: »

I'll ask them.

Thank you! Would be curious to hear the reason.
I am assuming you are not being sarcastic.

I would assume some mild series resistance on the tweeter would raise the impedance between 3.3 and 3.6 kHz a bit higher, but not sure what their goal or reasoning was.

Mr. Swauger is in a position to do as he says.

[Deleted User]

I sent your question to Scott Orth (the crossover's designer) but have not received a reply.
If I had to venture a guess the answer is that all speaker designs are a question of balancing various variables. If a designer makes a change in one area, say speaker sensitivity, then that causes changes in other areas. The speaker gets bigger, for example. That's why they use a speaker modeling program to see what changes in one area do to the whole design. Then they build a prototype of the design and begin making measurements and making small changes to fine tune some more. Then they have to make sure the manufacturer can build the design and test each component before it goes into production. I've seen these guys build the assembly line test rig and bring it to where the production is going to happen and then teach the assembly workers how to calibrate and test each subassembly. The speaker itself is only half of the required job.
But I digress.

Hansvelton

KennethSwauger wrote: »

I sent your question to Scott Orth (the crossover's designer) but have not received a reply.
If I had to venture a guess the answer is that all speaker designs are a question of balancing various variables. If a designer makes a change in one area, say speaker sensitivity, then that causes changes in other areas. The speaker gets bigger, for example. That's why they use a speaker modeling program to see what changes in one area do to the whole design. Then they build a prototype of the design and begin making measurements and making small changes to fine tune some more. Then they have to make sure the manufacturer can build the design and test each component before it goes into production. I've seen these guys build the assembly line test rig and bring it to where the production is going to happen and then teach the assembly workers how to calibrate and test each subassembly. The speaker itself is only half of the required job.
But I digress.

Thanks for taking the time.
My question was not meant to criticize the L100 speaker, but more to find insight into the design process, based on the comments from measurements I read on Stereophiles measurement section.
I was not sure if Polk Engineers frequent the forum (which I guess I somewhat had assumed) and was hoping for possibly some comments in regards to that current review as to the how and why they chose this or that in design.

[Deleted User]

No problem, I didn't think you meant anything critical, it's an interesting question. I once asked Scott why there were so many components on an LSi crossover? With a nod toward the movie "Amadeus" he said, "There are just as many components as needed, your majesty."

[Deleted User]

Here is Scott Orth's response to @Hansvelton 's question:


"I have many reactions to this type of question. The professional in me says I should answer in a polite, instructive manner. My ego says otherwise. Let’s let civility prevail.

Loudspeaker design is all about making choices. We have to decide what will be the priority. Focusing on the L100 and the questions posed, I will share choices we made and why.

As you know, pipes resonate. Larger pipes resonate louder than smaller ones. Larger ports have less port noise and greater output capability. Since one of our goals was to make a loudspeaker with outstanding bass for its size, we opted for a larger port. The cost is a bit more port resonance in exchange for more output and less port noise at high levels.

Note that the measurement of the port is taken by placing a microphone right next to the port tube’s output, a near-field measurement. We don’t listen like that. This is validated from the from the article:
“… I note that KM wasn't bothered by any coloration that would have resulted from the midrange peak in the port's output. Perhaps this is due to the fact that the port both faces away from the listener and is obscured by the cone-shaped diffusor. " Jon Atkinson is correct. The L100 has better bass than any speaker it’s size has a right to and the port is part of that equation. Ken Micallef gets it: “The L100 has a rich midrange, but its low end is its crowning glory, knocking me flat with its surprising apparent extension, warmth, and weight. This may be the most forceful speaker I've encountered of its size.".

As for the impedance, the speaker is at or above about 4 ohms until you hit about 3kHz. The energy in music is trailing off and is much more impulsive at higher frequencies so lower impedances are not much of an issue. When designing these speakers, we assumed folks purchasing speakers at these price points would have capable amplifiers. We tried and demoed the L100 on many different sets of electronics ranging in price from $500 to $7000 and the speakers sounded good on all of them. They certainly benefit from the better electronics, but would you expect it to be otherwise?

As with all measurements, the EPDR must be taken in context and used as intended. I suggest reading the AES paper on the subject before putting too much weight in it. You’ll find tidbits like the fact that the study deals with class B amplifiers and other classes of amplifiers will react differently to the complex loads that loudspeaker present. It’s a useful tool though, as it helps us to understand how the combination of magnitude and phase angle in the impedance affects an amplifier. We need more tools like that. Also, note that the EPDR is “peak” dissipation and so looks inflated in severity compared to the standard impedance magnitude and phase.

From a design point of view, bandwidth, sensitivity, frequency response linearity and impedance are all inter-related. Again, we chose bandwidth and frequency response linearity. We could’ve have opted for a higher impedance or more sensitivity, but then folks on the internet would be asking “Why, with 40 engineers, would allow a speaker with such poor bass response or non-flat frequency response to exist?”. We believe the L100 is the right balance of bandwidth, sensitivity, frequency response and impedance, tuned in the Polk tradition. And I think the critical reviews from the folks at Stereophile and Absolute Sound confirm we made the right choices to create an amazing speaker. By the way, our product development teams are much smaller and the size of the team does not determine the performance of a product.

Cheers,

Scott"

maxward

Thank you, Ken and Scott. Good information.

rooftop59

That’s a great response, Scott! I’m glad coolest heads prevailed.

I am now more curious to here this little guy. I liked the L200, but the price - while competitive - isn’t great. The L100 is definitely more affordable for us not-Joeys...

mhardy6647

rooftop59 wrote: »

That’s a great response, Scott! I’m glad coolest heads prevailed.

I am now more curious to here this little guy. I liked the L200, but the price - while competitive - isn’t great. The L100 is definitely more affordable for us not-Joeys...

My sentiments exactly (FWIW) -- the L200 sounded very good but seemed half-again as expensive* as its bits and pieces (and sound) justified.

__________
* I am one of the 4/3rds of Americans who is none too good with fractions. By this I mean I'd put the value of what I saw and heard at ca. 2/3 of the asking price. It is a good loudspeaker, but $1800 the pair for such a small and relatively ordinary two-way, ported loudspeaker is putting one in some pretty fast company.

I do note that Crutchfield (still) has 'em on sale for $1500 the pair. Better, but still a little high.

Viking64

rooftop59 wrote: »

to here this

dromunds

Thank you Scott, and Ken. I love the L200’s.

rooftop59

Viking64 wrote: »

rooftop59 wrote: »

to here this

Your neurotic. You should sikh affectional attention...

mhardy6647

Picts or it didn't happen.

TopperDude

Wonderful explanation that really helped better understand the design process. Am a huge fan of the L100. Normally don't like to settle for a bookshelf less than 6.5" for my personal system but after spending a lot of listening time with the L100, I could definitely live with that

[Deleted User]

Thanks for everyone's comments, I've forwarded some to Scott.

Hansvelton

KennethSwauger wrote: »

Thanks for everyone's comments, I've forwarded some to Scott.

Hey, thanks for taking the time. Very interesting to hear from the guy or guys that designed it.

[Deleted User]

You're welcome!