GR Research Klipsch RP-600M Upgrade Review (speaker)

[voodooless]

Also by using shallower slopes he worsens the vertical directivity and distortion behaviour

I was wondering about the vertical polar looking that badly. Erin’s vs II looks a lot better as does the original. Distortion wise though, it’s doesn’t seem to be an issue though. EQ is indeed still the cheaper option.

 

[ROOSKIE]

Yes, also in the RP-600M II which he has also measured.
Also by using shallower slopes he worsens the vertical directivity and distortion behaviour so I don't see his mod as a improvement, would rather EQ the dip or use/copy the crossover of the new version.

New version uses a new larger waveguide and I beleive a slightly modified woofer.
I dont think coping the crossover is guaranteed to be a great idea.

 

[Bruce Morgen]

So much for Amir supposedly having some sort of ongoing grudge or vendetta against GR Research -- when something is good, the dude posts the measurements and readily acknowledges when a modification results in an audible improvement. That's the technical competence, fairness, and integrity that set ASR apart in a world of marketing hype and half-baked advice presented as some sort of oracular wisdom.

 

[thewas]

New version uses a new larger waveguide and I beleive a slightly modified woofer.
I dont think coping the crossover is guaranteed to be a great idea.

Yes, possibly it might need some value changes.

 

[Nwickliff]

From measurements of the RP-500M II by Erin, it seems Klipsch has done much of this already if one were to get the later model. In that regard the kit looses its "raison d'etre" since its paying for something you can just about already buy.

I spent $200 less than the new with used old plus kit and learned soldering and xo schematic. Plus…..Speakers sound better when you worked on them. It’s science! Lol.

 

[uwotm8]

Looks like Klipsch do actually know what drivers they are working with and that dip is made for both "in-house sound" and avoiding that sawtooth-like upper midrange. I bet that latter can be worse to many ears as far as we - humans - get "calibrated" to frequency response, even pretty weird, in a few minutes. But not to resonances and distortion.

Anyway I wouldn't buy both for sure, stock or upgraded.

 

[voodooless]

Looks like Klipsch do actually know what drivers they are working with and that dip is made for both "in-house sound" and avoiding that sawtooth-like upper midrange. I bet that latter can be worse to many ears as far as we - humans - get "calibrated" to frequency response, even pretty weird, in a few minutes. But not to resonances and distortion.

But both distortion and resonances are significantly improved in that exact area...

 

[Absolute]

Not sure what to think of a shallow order filter, would be interesting to see compression test differences between the original + EQ and the GR modified one.
Having experimented quite a bit with crossover slopes and frequency points in a two-way I have to say there's a fine line between everything sounding perfectly clean and clear and sounding grainy and muddled.

 

[uwotm8]

But both distortion and resonances are significantly improved in that exact area...

Not really. Just changed. And there's a new spikes in "upgraded" compared to stock broad uplifts - I think that's a bad sign.

 

[DSJR]

Looking back over my decades in the UK industry, I think all of 'us' went through this desire for a lively 'engaging' kind of presentation and 'eff' tonality or natural timbres. In my case it was 1980's Linn-Naim systems which quacked and all but screeched their way through the post-punk albums we were buying (Siouxsie & The Banshees was a favourite band who tried to move their musical boundaries forwards with each new release). Eventually though, that kind of raw almost shouting quality starts to wear thin and I feel many of us wanted a more refined sound without losing some of that 'eagerness' for want of a better word.

I do appreciate the scene was and is perhaps different in the US, but I'm seriously please that Klipsch have responded with refinements to almost all their range I gather, the current versions still being 'their way' of presenting the soundfield, but in a very much more refined way. I'm sure there are hundreds or even thousands of pairs of the V1 model here and if these updates can help to improve what's there, it saves the older model being cast aside. Whether you actually need the tube connectors, non-steel fixings (WTF?) and foo crossover caps? is another matter, as stock components at this level would do it exactly the same I suspect. Maybe finding out the exact revised crossover values is something for DIY Audio to research?

Anyway, I'm really sad that getting these speakers in either form over here adds so much to the cost and makes them uncompetitive in most respects (JBL 305's are still cheap enough here).

 

[voodooless]

Not really. Just changed. And there's a new spikes in "upgraded" compared to stock broad uplifts - I think that's a bad sign.

That can just be a wire or some other thing resonating in the enclosure, arisen from doing the mod. This is probably not caused by a crossover upgrade (at least not the parts) and with some carefull figuring out can be fixed easily.

Were talking about the 500 Hz to 3 kHz range here:

Those "sawtooths" in the response are very much inaudible.

I wonder how much of that 400 to 1.5 kHz distortion is caused by the electrolytic cap that is in the original filter?

 

[milosz]

Looks like GR is well aware of this:

… apparently steel nuts for the binding posts would negatively affect the sound

If you had steel nuts, wouldn't that negatively impact your sound? It would mine, for sure!

 

[Lorenzo74]

This is a review of a Klipsch RP-600M which has been upgraded to a new crossover, binding posts and "No Rez" by GR Research. The kit costs US $244.
View attachment 215422

OK, so there is nothing externally which is different. I can't open the unit to show the different bits but here is the back with new binding posts (two are in parallel):
View attachment 215423

I performed all of my testing using the standard binding post.

My old review of RP-600M did not have the latest measurements so what you see is me adding those measurements.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

Reference axis is the tweeter.

Klipsch RP600M With GR Research Mods Measurements
I am going to contrast the stock version with the new. The former will always be on the left. Let's start with the all important spin/frequency response:

View attachment 215424

The stock version is fatally flawed in crossover region with that large hole. GR Mod uses a first order (?) filter to make the two drivers roll off slower and thereby, filling that whole. This gives us a much more flat on-axis response. There is a cost though in sensitivity which drops by 3 or so dB.

We can see the correction better in near-field measurement:
View attachment 215426

There were to port/cabinet resonances in the stock version which are gone now. Whether this is due to padding being different, I can't tell. But it is certainly welcome.

The fix naturally improves the early window response:
View attachment 215427

And with it, predicted in-room response:
View attachment 215428

So very good job there. Let's now look at distortion. This was tricky as I had to match levels. Doing so with speakers of different response is non-trivial but I got close:

View attachment 215429

At 86 dBSPL above, it is hard to see much of a difference. Going up to 96 dB gives us more data:

View attachment 215430

Stock unit has that broad distortion hump. That is much reduced with the mod but now there is a sharp resonance. There is some reduction of distortion at the far side of the spectrum with the mod.

Company makes a lot of hay out of CSD waterfalls so let's look at that:
View attachment 215431

Seems like some reduction in resonances. The peak in the stock speaker around 800 Hz is gone which results in less ringing there.

Impedance and phase plots also show similar improvement:
View attachment 215432

Impedance is also brought up a bit which is nice.

I was interested to see the impact on directivity. Alas, my Klippel software is no longer compatible with old files to view/generate them. I have to find out why so here are the data for the modded one:

View attachment 215433

We see controlled directivity courtesy of that waveguide although the tweeter does start to beam/narrow. Even prior, we have rather narrow angle which likely helped with extra energy/sensitivity in that region.
View attachment 215434

Vertically we have the standard issues with 2-way design so stay at tweeter height:

View attachment 215435

Listening Tests
I started listening to the stock RP-600M and immediately noticed its brightness and lack of spectrum in mid frequencies. I switched it out for the modded version and improvement was substantial. The sound was tonally very balanced now. I thought the highs were a little unnatural so switched out the speaker for Revel M105. There was too little bass in that smaller speaker to compete so I put it aside and put on the Revel M15. The Revel projected a much larger/diffused sound which I much preferred to the RP-600M. I switched back to it and the vocals seemed to shrink to the middle of the RP-600M cone. This is backed by the directivity plot (which I had not seen at the time).

The dynamics were a bit more limited with the mod due to its lower sensitivity. And by this I mean it started to get distorted a bit less than the stock speaker did. Impact was in bass frequencies which became progressively ugly. That said, this was happening at fairly high playback level and with one speaker. So as a practical matter it should be fine if you have enough amplification power.

Conclusions
The flaw in stock RP-600M is so obvious and so is the solution. It was reassuring to see GR Research correcting the response and smartly using lower order filters as to keep the cost down. The difference is dramatic. I can't listen to the stock version. But with the mod, the combination was definitely a contender. You lose some sensitivity so better have a good sized amplifier. The narrow directivity is not to my taste but may be to yours.

Overall, this is a job well done by GR Research and I am going to recommend it to owners if they are not inclined to use my software EQ fix.

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Thank you @amirm , actually Klipsh released the RP600 version MK2.

I wonder if you could get a sample of the new one since I wonder the opportunity of buying a MK1 and tune it with such expensive and heavy modification that will void warranty.

Also the 500M has a new version.

Both MK2 addressed suboptimal (maybe intentional) crossover design that do not properly overlaps drivers in the XO region.

My Best

 

[amirm]

Thank you @amirm , actually Klipsh released the RP600 version MK2.

Here is the problem. I am out almost $500 on the first version! It is now just taking up space. Spending more money on the brand doesn't seem very enticing to me.

 

[abdo123]

Yes, due to the less steep slope the vertical directivity and distortion suffers, so I would rather equalise it or just buy the successor generation as Klipsch corrected that dip there:

Klipsch RP-600M II Bookshelf Speaker Review

Klipsch RP-600M II Review

www.erinsaudiocorner.com

Klipsch RP-600M Bookshelf Speaker Review

Klipsch RP-600M Review

www.erinsaudiocorner.com

Klipsch RP-500M II Bookshelf Speaker Review

Klipsch RP-500M I Review

www.erinsaudiocorner.com

Klipsch RP-500M Bookshelf Speaker Review

Klipsch RP-500M Review

www.erinsaudiocorner.com

Yes anyone with their right mind should buy the second iteration and just play with toe-in. Response at 20 degree off-axis is very flat.

However if you’re not a fan of narrow directivity speakers these are not for you.

 

[uwotm8]

"sawtooths" in the response are very much inaudible

I don't think so, but that depends on music. May be Ok for "Romantic Women Voices vol.999", but what to do with Carcass or Behemoth?
Even Rammstein soy-metal has some aggressive guitars and such saw will nicely colorate it instead of softly pulling back like typical V-shaped FR speakers/cans.
Both sorts of degradation are bad for sure.

 

[Lorenzo74]

Here is the problem. I am out almost $500 on the first version! It is now just taking up space. Spending more money on the brand doesn't seem very enticing to me.

@amirm you are a star... just sign it and sell it on ebay. you'll be surprised.
by the way I'm puzzled that Klipsh marketing dept. didn't offer you yet samples of RP 500MK2 and RP600 MK2 (include prepaid return shipment) just to show how much they care of your reviews since (i feel) they invested in upgrading the design because of your measurements...

PS by when you will manage to get your valuable hands on really high ends products such as the ones very positively (subjectively) reviewed by Stereophile? according to my feeling as happened in the DAC world the legacy industry of expensive high end speaker/cable/stands/spikes... is at the eve of a revolution. As soon as you start to show headless panthers of >50k$ multi drivers towers we will see the real power and the undisputable value for music lovers of ASR community
while waiting, thank you very much.
L.

 

[BDWoody]

Folks at GR Research:

 

[kokakolia]

I thought that the RP600M were so lifeless that I bought fullrange speakers.

But that's news to nobody. GR Research did an extensive review on the RP600M and this ASR review confirms it.

Also note that you lose a lot of detail if you're not listening to the RP600M head-on. The vertical off-axis response is rather poor. I'm imagining that most RP600M owners (with sub-optimal speaker placement) are confused by the glowing reviews.

This mod is interesting for the DIY crowd because you can score used RP600M speakers for cheap. I sold my pair to a guy who wasn't happy with his LS50s. It's funny because LS50s measure really well, so you'd expect people to enjoy them over the RP600M.

 

[Steve Dallas]

Considering recent events with the LGK, it's good to see not all is lost with Danny and GR. I'd imagine he is pretty confused right now though with ASR...

A through comparison review Amir.


JSmith

Being that this is merely Audio THEORY Review's opinion, it has to be false, and this has to be a terrible, worthless mod for the sake of consistency on his part!