GR Research Speaker Upgrade Review (Sierra-2EX V2)

[atomicmist]

I know GR-Research has a loyal following, and apparently all it takes to become a loudspeaker design savior is a camera, a bunch of fancy looking crossover parts, and the ability to look disappointed at factory capacitors.

Somehow, we are expected to believe that some very established loudspeaker companies, many with anechoic chambers, Klippel systems, trained engineers, and decades of design experience, all tragically forgot how to design crossovers.

Danny does not appear to have measurement facilities comparable to a Klippel NFS system, like the type used by Erin Hardison at Erin’s Audio Corner, or the advanced facilities used by major manufacturers. Without full before-and-after data, including off-axis response, sound power, distortion, impedance, and compression behavior, these “upgrades” look more like boutique parts marketing than serious engineering.

That does not mean DIY crossover work has no value. Experimentation is part of the hobby, and alternative voicing can be fun. But changing the voicing of a speaker is not the same as improving it.

My concern is that GR-Research often presents parts-based modifications as objective improvements to proven loudspeaker designs and often implies that manufacturers are either incompetent or cheap. From what I have seen, and in a few cases heard, his so-called upgrades often appear to compromise performance rather than improve it, especially when the original design had already been optimized within its intended engineering and cost constraints.

People can spend their money however they like. But let’s not pretend every speaker is broken until it receives the sacred crossover spa treatment.

 

[cavedriver]

I'm really pondering when a customer is going to sue him for false advertising, etc. He's a crook (although to be fair an enormous portion of audiophilia is essentially self-delusional pandering to criminals, so...)

 

[Purité Audio]

Questionable business practises aside, in terms of personal hygiene Danny has come a long way.
Keith

 

[Talisman]

I've been telling the guy that his test gear is grossly inadequate for years -- he uses some elderly Clio system from Italy which is to a Klippel NFS what a rusty Fiat 500 is to a Mercedes-Benz S-Class.

Hey! Show some respect to an old classic....
it does not deserve this comparison

 

[Maxim-ICOM]

Somehow, we are expected to believe that some very established loudspeaker companies, many with anechoic chambers, Klippel systems...

It looks like a marketing - if you have nice anechoic chamber or Klippel does not mean that company build outstanding speakers.
I know a companies who build excellent speakers and do not use Klippel.
It is more matter of engineering and Klippel or Clio or any other measurement system is just a tool what help to design a speaker.

 

[courtesy]

It looks like a marketing - if you have nice anechoic chamber or Klippel does not mean that company build outstanding speakers.
I know a companies who build excellent speakers and do not use Klippel.
It is more matter of engineering and Klippel or Clio or any other measurement system is just a tool what help to design a speaker.

Or it just means you have invested in great tools.

 

[Maxim-ICOM]

I've been telling the guy that his test gear is grossly inadequate for years -- he uses some elderly Clio system from Italy which is to a Klippel NFS what a rusty Fiat 500 is to a Mercedes-Benz S-Class.

I see Clio vs Klippel like this :

 

[Laserjock]

What Panther would the original speaker without the mode get?

American built, Klippel design help.

 

[dfuller]

Check out the thread linked below. Thanks for testing, measuring and creating that thread @ctrl

Now we see the effect of the higher inductive part of the sand-cast resistor, because at high frequencies the frequency response drops slightly compared to the low-inductance resistor - up to 20kHz by as much as 0.02 dB!

Even if the effects should increase at higher resistance values, even 5 times the value is inaudible.

The effects of replacing a sand-cast resistor with a low-inductance resistor are practically zero.

Replace resistor by low-inductance resistor - Is it audible?

Since it is often claimed here in the forum that replacing cheap sand-cast resistors with low-inductance resistors would lead to clearly audible improvements, and since it's no use pointing out that the sound change (unless it's completely imagined) is very likely due to slight deviations in the...

www.audiosciencereview.com

As I said: No speaker company is stupid enough to use wirewounds with stray inductance high enough to be a problem... mostly because you would need to try to get ones with high enough stray inductance.

I see Clio vs Klippel like this :
View attachment 530206

So the Klippel is the one on the left, right?

 

[Everett T]

Posting this before it gets deleted:

Is GR using outdated measurements for kits/mods? Klippel Wrong measurements?

Is GR using outdated measurements for kits/mods? Klippel Wrong measurements?

www.audiocircle.com

View attachment 529978

So Danny took the poster's words and changed what the intent of the post was all to make his reply fit **his** narrative, ffs? Also, does Danny think that major audio manufacturers are still using Cliio?

 

[DatSpeakerTho]

So Danny took the poster's words and changed what the intent of the post was all to make his reply fit **his** narrative, ffs? Also, does Danny think that major audio manufacturers are still using Cliio?

Danny doesnt really think much at all.

 

[atomicmist]

It looks like a marketing - if you have nice anechoic chamber or Klippel does not mean that company build outstanding speakers.
I know a companies who build excellent speakers and do not use Klippel.
It is more matter of engineering and Klippel or Clio or any other measurement system is just a tool what help to design a speaker.

I can't disagree with that. Having advanced measurement systems does not automatically make someone a great loudspeaker designer.

That said, if two designers are working with the same drivers and enclosure, I would still place my bet on the one with better measurement tools, better data, and a more complete understanding of the acoustic system. Better tools do not guarantee a better result, but they certainly improve the odds when used properly.

 

[kemmler3D]

Somehow, we are expected to believe that some very established loudspeaker companies, many with anechoic chambers, Klippel systems, trained engineers, and decades of design experience, all tragically forgot how to design crossovers.

I think it's similar to how 'alternative medicine' and 'wellness' is sold. Mainstream medicine is either ignorant of how to cure you (but me, the untrained expert, knows more), or knows how to cure you, but is withholding the cure because of MONEY. THEY won't do the right thing because of MONEY, therefore you should give ME some MONEY instead.

The logic is never spelled out in so few words, it falls apart without extra padding to keep the whole contradiction from coming into view at once.

 

[Buckchester]

As I said: No speaker company is stupid enough to use wirewounds with stray inductance high enough to be a problem... mostly because you would need to try to get ones with high enough stray inductance.


So the Klippel is the one on the left, right?

Ya I couldn’t tell either…

 

[AaronJ]

So Danny took the poster's words and changed what the intent of the post was all to make his reply fit **his** narrative, ffs? Also, does Danny think that major audio manufacturers are still using Cliio?

You’re using too much brain power to try and make heads or tails out of what he is thinking. This is narcissism playing out in a public forum. Don’t overthink it.

 

[tw 2022]

Questionable business practises aside, in terms of personal hygiene Danny has come a long way.
Keith

lol...

 

[Endibol]

Danny needs to Work with a klippel, that would be a real step Up for His speakers and Upgrades than any harp device what so ever...

If Danny had a Klippel he would find out that his upgrades are not needed at all…

 

[Frank207be]

Waiting for Danny to upgrade a Tekton speaker. That's long overdue...

 

[holbob]

Waiting for Danny to upgrade a Tekton speaker. That's long overdue...

A battle of wits between two unarmed opponents. They are very competitive.

 

[Chaos01]

He fundamentally misunderstands how the Klippel NFS works.

It does not “average multiple mic positions.” It reconstructs the full 3D sound field and derives a mathematically correct anechoic on-axis response. So the on-axis data from Erin's Audio Corner is pure 0°, not mixed with off-axis.

He’s likely confusing this with estimated in-room response, which does combine multiple angles—but that’s a completely different metric.

His claim that Klippel “averages in off-axis” (causing extra HF peaks) is incorrect. Those features are real and often captured more accurately by NFS. If they don’t show up in his measurement, it’s due to typical limitations (gating with 1/3 octave, mic placement, old mic, old calibration, resolution), not because Klippel is “adding” anything or simple because Erin measured the MKII !?

Also problematic:

• A single-point measurement is not more “real” than NFS — usually less accurate
• Differences aren’t just “scaling/zoom” — that’s misleading
• Flat on-axis alone ≠ better speaker (directivity matters)
• Claims about crossover parts “sucking life out of the signal” lack solid evidence

Biggest misstakes:
Klippel NFS = “average of many measurements” → wrong
On-axis from Klippel includes off-axis → wrong
Confusion with estimated in-room response → likely
Peaks in Erin’s data come from averaging → wrong
His single-point measurement is “more real” → opposite is true

Bottom line:
He mixes up on-axis, off-axis, and in-room metrics, and misrepresents what Klippel data actually shows.
Also he claims to be a better engineer than the JBL engineers, my guess is that they voiced this model to a "old school" fr-response and Not because JBL engineers are incompetent...

Danny Richie from GR Research answered to my YouTube comment and claimed that nothing of that is true. Why the Heck cant he say that there was something wrong in His Video...
I will Screenshot my comment and uploade here, so usually he deletes complex comments Like this at YouTube...

Edit: there we go, my answer is not there anymore. At least it seems that he deleted his answer too.
And if someone is interested, what the Klippel is doing, here is a link to a presentation that explain that is far more than average something: https://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Transparancies/Holographic directivity measurement of line sources and sound panels.pdf
To summarise it:

Why mathematically it is NOT “just averaging measurements”​

The important distinction is:
The system is not doing:

“Take many microphone curves and blend them together randomly.”

Instead, it is reconstructing a continuous acoustic field first.
That is fundamentally different.
The Klippel NFS measures:

• magnitude
• phase
• spatial behavior

and decomposes the sound field into spherical harmonic coefficients.
Very simplified:
Instead of storing:

• “measurement at 0°”
• “measurement at 10°”
• “measurement at 20°”

the system builds a mathematical model of the radiating sound field itself.
Only after that reconstruction can you calculate:

• On-Axis
• Listening Window
• Sound Power
• PIR

as derived quantities.
So mathematically:
the averaging happens on top of an already reconstructed physical model.
Not on raw microphone data.

Why this distinction matters:​

A simple arithmetic average destroys spatial information.
For example:
If you literally averaged:

• front radiation
• side radiation
• rear radiation

you would lose:

• directivity structure
• phase relationships
• radiating vs reactive behavior
• interference information

But the NFS preserves all of that because the field reconstruction happens first.
That is why the system can:

• reconstruct virtual microphone positions
• calculate arbitrary distances
• separate near field and far field
• identify non-radiating energy
• simulate crossover changes

A simple averaged microphone measurement could never do this.

Another important distinction: Averaging vs Integration​

Metrics like:

• Sound Power
• PIR

are closer to spatial integrations or weighted energy calculations than to “simple averaging.”
For example:
the Sound Power curve effectively represents the total radiated acoustic energy over a sphere.
That is not:

“average of some curves”

in the casual sense people often mean online.
It is a physically meaningful radiation integral.
Similarly, PIR uses psychoacoustic weighting:

• some angles matter more
• some less
• reflections are weighted differently

So it is not:

every angle equally averaged together.

The key misunderstanding online:​

People often incorrectly jump from:

“PIR uses multiple angles”

to:

“therefore the On-Axis curve is also averaged.”

That conclusion is false.
The reconstructed On-Axis response is:

• one exact direction
• derived from the acoustic model
• not a weighted room estimate
• not a blend of off-axis curves

The averaging/integration only applies to derived metrics like:

• Listening Window
• Sound Power
• PIR/EIR