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

[Geert]

What's also nice is how he downplayes the audibility of distortion, but at the same time believes to be able to hear the alignment of electrons in a cable.

 

[Randolf]

He says he is using a 4mS gated window, which is equivalent to a 250Hz frequency resolution, and which is why he can't display any information below 200Hz !! What his software is probably doing is zero-stuffing the time response to 100 mS to get 10 Hz plot resolution, but there is still no more detail than with the original 4 mS window. It just smooths out the frequency response plot rather than leaving jagged lines connecting the points at each 250Hz interval, which is akin to oversampling in the frequency domain. Anyone who has studied FFT's will know this. This is why striving for high tap-count convolution filters in the reproduction chain is pointless if the sampling interval is limited and does not match. Hate to rain on his parade but Amir was not lying !!

Such statements of Danny also bother me most because of its disinformation. So also added a comment to his Youtube video about this:

@randolfwerner2117 2026-05-11T21:46:53Z Likes: 18
With a time gate of 5ms the low frequency limit rises to 200Hz. Above 200 Hz,
the measurement is still usable, but the gate introduces a tradeoff in frequency
resolution and smoothing behavior. The measurement is effectively averaged over
roughly 200 Hz bins. This is why gated measurements look smoother in the lower
mids as the response really is. The "IR Window" of REW e.g. calculates this from
the Windows length and the calculated value is correctly named "Freq.
Resolution" and not "Freq. lower limit".

I try just to focus on the facts and let everyone draw his own conclusions. Luckily due to AI many people have started verifying claims on their own, which often gives surprisingly good results.

Serious people like Audioholics know about the limitation of their measurement technique and correctly describe it, e.g.:
"...speakers were measured in free air at a height of approximately 9 feet and gated at 14 ms. At this window gate, some resolution is lost below 140 Hz, and accuracy is completely lost below 70 Hz and so that range should be ignored."

Danny in his video instead says (showing Amir's graph):
"...and it's talking about the gated measurement and he wrote "Gated measurement means low resolution", which is an absolute lie. Like that's just a total lie. The gating has nothing to do at all with resolution.... I did have a full-size anechoic chamber when GR reserach first started. ...was like 23 feet Long.... we could take accurate measurements down to about 40Hz or so, but I could take the same measurement outside of the anechoic chamber out in the listening room with that new CLEO System and I can do a gated time window and I could get the exact same measurement. I just cant' measure as accurate down low I can't get far away in the root without room reflections. Has nothing to do with resolution. It just has to do with how low I want to look."

BTW if you want do download Youtube comments and replies and you are not happy with other tools you may want to have a look at my little python tool: https://github.com/rwhomeaudio/GetYouTubeComments
Unfortunately I cannot generate the reply on reply hierarchy, but interestingly it somestimes can download more than you see in the Youtube WebUI, e.g. I added a reply to a reply to my comment above which is not visible (anymore) in the WebUI but my tool can download it, strange!

 

[Geert]

Lookily due to AI many people have started verifying claims on their own, which often gives surprisingly good results.

Let's do another one then, based on Danny's claim "I did have a full-size anechoic chamber when GR reserach first started. ...was like 23 feet Long.... we could take accurate measurements down to about 40Hz or so" (using foam wedges as he explains later in the video):

Q: "Is it realistic to build a anechoic chamber that allows you to measure speakers down to 40Hz?"

A: Measuring speakers down to 40 Hz in a true anechoic environment is technically possible but extremely challenging due to the physics of sound absorption at such low frequencies. <Edit: Some highlights from a very elaborate explanation>:

• The chamber must be at least 1–2 wavelengths across in all directions to avoid standing waves. This implies a chamber roughly 17 × 17 × 17 m or larger just to manage 40 Hz free-field conditions. Required wedge lengths: ~2.1 m
• Low-frequency absorption requires very dense fiberglass, mineral wool, or specially engineered resonant absorbers. Conventional foam wedges are ineffective below 100 Hz
• Most professional loudspeaker anechoic chambers, such as Lynx Pro Audio’s, start at approximately 100 Hz, which is considered realistic for high-accuracy free-field measurements. Achieving a reliable 40 Hz cutoff has rarely been attempted on a commercial scale due to space, cost, and engineering constraints, and is generally reserved for extreme research facilities.

 

[Adis]

Danny responds to Amir. And does a pretty good job explaining what he does and poking some holes in Amir’s argument. Danny also pulled receipts of Amir and his website supporting Danny’s perspective of what impedance swings, mismatches and out of phase or current leading and lagging voltage and its affects on SQ. I watched both videos because I want to see the arguments of each and make my own opinions on how they frame their perspectives. They both make great points that are educational. I don’t care about either guy. I don’t have a dog in this fight. I like opposing viewpoints because I will never blindly follow any person.

What Danny is trying to do is convince you that measurements are irrelevant. Unless done by him...

 

[AaronJ]

Amir, this guy is not worth your time. I am just a bystander and have trouble keeping my own emotions out of it. The best thing anybody can do with people like Danny is to distance themselves from him because he will argue like a toddler until the end of time. He cannot be reasoned with, and the same goes for people he has successfully duped. Things will get much worse for you and everyone else the more he feels like he's backed into a corner. It's no different from Eric Alexander. Treat yourself to a spa day to wash off the stench of this guy and move on.

 

[AscendDF]

Let's do another one then, based on Danies claim "I did have a full-size anechoic chamber when GR reserach first started. ...was like 23 feet Long.... we could take accurate measurements down to about 40Hz or so" (using foam wedges as he explains later in the video):

I remember well when Danny used to claim he had an anechoic chamber. This was a long time ago, perhaps back in the early 2000's.

Not long after our CBM-170's were measured in the anechoic chamber at Canada's NRC, I had a disagreement with Danny's old boss, Mark Schifter, about the "anechoic chamber" claim. I told him it was more of a treated room than an actual chamber. It was far too small and did not have the requisite suspended mesh flooring over thick fiberglass wedges to absorb floor bounce.

Danny's "wedges" were only about 4 inches deep, maybe 6" at most and were open cell acoustic foam. At such limited thickness and the wrong material, it would, at most be "anechoic" down to, at best 500-600Hz - assuming the floor was covered in wedges and the walls were thick concrete.

His claim of anechoic to 40Hz is absurd, he either truly doesn't understand or is just outright lying. To be anechoic to 40Hz would require specialized fiberglass wedges (not acoustic foam) that would need to be at least 4 FEET in depth. I believe there are only a few chambers in the world that are anechoic to this low of a frequency. Even the widely used chamber at the NRC is generally only good down to ~ 80Hz.

Here is a pic of GR's so called anechoic chamber from their website back then...

I spent many months researching chambers when we had our main facility in Gardena, CA (~2+ decades ago) We had the space but the cost was astronomical, with the lowest quote for a chamber tuned to ~100Hz being around $300K. I did considered it, but child # 2 was soon on the way and as such, decided to stick with ground plane and nearfield techniques. We had a large flat parking lot which made taking ground plane measurements simple when everyone in the business park would go home. Many late nights back then, good memories for me.

 

[Geert]

I spent many months researching chambers when we had our main facility in Gardena, CA (~2+ decades ago) We had the space but the cost was astronomical, with the lowest quote for a chamber tuned to ~100Hz being around $300K.

It's telling when someone attempts to DIY such a chamber and doesn't ask himself why lots of established manufacturers use ground plane and nearfield measurements instead. But then Danny tells it like 'been there, done that'...

 

[jtwrace]

I remember well when Danny used to claim he had an anechoic chamber. This was a long time ago, perhaps back in the early 2000's.

Not long after our CBM-170's were measured in the anechoic chamber at Canada's NRC, I had a disagreement with Danny's old boss, Mark Schifter, about the "anechoic chamber" claim. I told him it was more of a treated room than an actual chamber. It was far too small and did not have the requisite suspended mesh flooring over thick fiberglass wedges to absorb floor bounce.

Danny's "wedges" were only about 4 inches deep, maybe 6" at most and were open cell acoustic foam. At such limited thickness and the wrong material, it would, at most be "anechoic" down to, at best 500-600Hz - assuming the floor was covered in wedges and the walls were thick concrete.

His claim of anechoic to 40Hz is absurd, he either truly doesn't understand or is just outright lying. To be anechoic to 40Hz would require specialized fiberglass wedges (not acoustic foam) that would need to be at least 4 FEET in depth. I believe there are only a few chambers in the world that are anechoic to this low of a frequency. Even the widely used chamber at the NRC is generally only good down to ~ 80Hz.

Here is a pic of GR's so called anechoic chamber from their website back then...


I spent many months researching chambers when we had our main facility in Gardena, CA (~2+ decades ago) We had the space but the cost was astronomical, with the lowest quote for a chamber tuned to ~100Hz being around $300K. I did considered it, but child # 2 was soon on the way and as such, decided to stick with ground plane and nearfield techniques. We had a large flat parking lot which made taking ground plane measurements simple when everyone in the business park would go home. Many late nights back then, good memories for me.

I have personally been in Harman's anechoic chamber, I can say for certainty that GR never had anything like it. Remember though, he also claims the CLIO is the same as Klippel NFS.

 

[AscendDF]

It's telling when someone attempts to DIY such a chamber and doesn't ask himself why lots of established manufacturers use ground plane and nearfield measurements instead. But then Danny tells it like 'been there, done that'...

Impossible to DIY an anechoic chamber, one can't even buy the highly specialized wedges, but I understand your point. Yes, one can achieve good results using ground plane or nearfield techniques. But that isn't even necessary when someone can simply send off a design to have it measured on an NFS. I have run full scans for several companies that have simply asked for a favor, I believe one of these companies proceeded to then purchase their own NFS.

 

[AscendDF]

I have personally been in Harman's anechoic chamber, I can say for certainty that GR never had anything like it. Remember though, he also claims the CLIO is the same as Klippel NFS.

Me too, in Northridge - a very long time ago. Great experience, but incredibly uncomfortable in the chamber after only a few minutes.

 

[dfuller]

I thought maybe it is interesting to actually visualize the effects of time gating and smoothing. I imported Erin's JBL L100 Classic MKII on axis measurement into REW, used "Generate minimum phase..." to generate an impulse response and applyed various levels of gating and smoothing up to the degree Danny does:

View attachment 531754

View attachment 531755

So his measurement error is a combination of both. There are bumps that pop out from the gating pretty bad. I'm not sure what the point of gating that hard is other than "I don't want to bother with ground planes or going outside"...

 

[Randolf]

So his measurement error is a combination of both. There are bumps that pop out from the gating pretty bad. I'm not sure what the point of gating that hard is other than "I don't want to bother with ground planes or going outside"...

Thanks to link in my post here, I accidently used the "wrong" thread (too much Danny currently in this forum ). I would not say it is a "measurement error", it is just a very easy way to create a low resolution measurement. He has to apply such a time gate because its an in room measurement and on top of it he likes to apply massive smoothing. It can be ok if you know about the drawbacks and limited significance of such technique, but Danny doesn't seem to be fully aware of this and makes false claims.

 

[Spkrdctr]

This man alligator clips like a champion

What the hell??? Correct me if I am wrong but aren't alligator clips very thin steel that is plated? I don't think they are brass or copper.......am I wrong? If I am right than it blows his tube connectors and other cheesy parts mantra out of the water.

 

[Ropeburn]

What the hell??? Correct me if I am wrong but aren't alligator clips very thin steel that is plated? I don't think they are brass or copper.......am I wrong? If I am right than it blows his tube connectors and other cheesy parts mantra out of the water.

Well freely spoken, it matters fuck all. Danny knows it. Which is indeed illustrating nicely how cognitively dissonant or straight up lying he is. I suspect it's something in the middle, as always.

 

[DatSpeakerTho]

I remember well when Danny used to claim he had an anechoic chamber. This was a long time ago, perhaps back in the early 2000's.

Not long after our CBM-170's were measured in the anechoic chamber at Canada's NRC, I had a disagreement with Danny's old boss, Mark Schifter, about the "anechoic chamber" claim. I told him it was more of a treated room than an actual chamber. It was far too small and did not have the requisite suspended mesh flooring over thick fiberglass wedges to absorb floor bounce.

Danny's "wedges" were only about 4 inches deep, maybe 6" at most and were open cell acoustic foam. At such limited thickness and the wrong material, it would, at most be "anechoic" down to, at best 500-600Hz - assuming the floor was covered in wedges and the walls were thick concrete.

His claim of anechoic to 40Hz is absurd, he either truly doesn't understand or is just outright lying. To be anechoic to 40Hz would require specialized fiberglass wedges (not acoustic foam) that would need to be at least 4 FEET in depth. I believe there are only a few chambers in the world that are anechoic to this low of a frequency. Even the widely used chamber at the NRC is generally only good down to ~ 80Hz.

Here is a pic of GR's so called anechoic chamber from their website back then...



View attachment 531742



I spent many months researching chambers when we had our main facility in Gardena, CA (~2+ decades ago) We had the space but the cost was astronomical, with the lowest quote for a chamber tuned to ~100Hz being around $300K. I did considered it, but child # 2 was soon on the way and as such, decided to stick with ground plane and nearfield techniques. We had a large flat parking lot which made taking ground plane measurements simple when everyone in the business park would go home. Many late nights back then, good memories for me.

Yeah, this tracks. Danny is a hugely insecure person and I wager everything he does is a manifestation of that. It's like they asked themselves "What makes a speaker company appear legitimate?" Why an Anechoic chamber of course. He obviously did not have the funds to make one, so instead of realizing it was a bad idea, he just doubles down and makes his own crappy version of it. He wants so desperatly to be seen as a real, respected speaker company but I think he's forever haunted by the failure of AV123 and the fact that the speaker world kind of forgot about him. His mods just come across as petty, like a little kid throwing rocks at other kids who didn't include him in their play time.

I was very much like Danny at some point, wanted a speaker company of my own. Looking back it's hilarious that I thought I had any chance at the time, that my DIY explorations were some sort of competitive product. I did what Danny never does, and that was to go out of my own bubble and see what the rest of the world has to offer. Not only would I have crashed and burned, I probably would've taken some people with me. I'm glad I got to learn my cutesy little speaker shop is a joke in the face of the industry.

Allowing myself to abandon old notions about what works is what let me grow. For Danny though he does not leave is bubble. He can't leave it, because it means the destruction of whatever self worth he has. Based on this articles time stamp, he's been in a state of arrested development for a very long time. Most people who work in various audio fields tend to hop around and not get stuck on one thing, so it's kind of sad to see that this is all Danny has done for the past 20+ years? A legacy of average to poor speakers, cemented in endless online bickering.

So yeah the dude is not only a liar, but he's a warning sign of what happens when you wall yourself off from the world. A great represenatation of how to live a shallow life.

 

[a4eaudio]

What the hell??? Correct me if I am wrong but aren't alligator clips very thin steel that is plated? I don't think they are brass or copper.......am I wrong?...

I'm not watching Danny's videos and assume he has crappy alligator clips...but to your general question, you can get nice copper alligator clips and use your own 12 gauge OFC cable. Some crappy/cheap alligator clips have a LOT of resistance.

 

[ahofer]

I just have also seen Danny's JBL L100 video and also stumbeled about his "Klippel averaging story" while refering to On Axis and Listining Window graph of Erin's Klippel measurment. He simply doesn't seem to understand that the On Axis response measured by the Klippel NFS is not averaged in any way and is in fact a extremly accurate high resolution measurement, which you otherwise can at best get from an ungated outdoor or anechoic chamber measurement and that instead it is his own time gated and 1/3 smoothed measurement which is degraded and low resolution. I am not sure if Danny didn't understand this or is intentionally trying to compromise the Klippel measurements.

I’m pretty sure which it is.

 

[G|force]

I have personally been in Harman's anechoic chamber, I can say for certainty that GR never had anything like it. Remember though, he also claims the CLIO is the same as Klippel NFS.

I have as well, and I am fairly certain the skill, time and materials just to construct the suspended floor with 4' deep fiberglass wedges below is out if his scope.

 

[Spkrdctr]

I was going to do a rebuttal to Danny's misinformation, lies and just plain wrong ideas. BUT, it is not worth my time. I, Amir, JJ and a bunch of others have been through all this for the last 40 years. As I have stated many times, new people come into the audio world and always ask the same questions over and over. If they paid us to answer their questions and educate them on audio science , then it would be ok, but for free in an online forum? New people need education from the most simple idea up to the engineering level. You can't teach that online in an audio forum.
The best version of it I have found is ASR. ASR has many audio engineers, Electrical engineers and others very well educated in the field. They do answer some questions all the time but to do a real deep dive it is not possible. Sooner or later you have to realize that Amir has no dog in the fight and calls a spade a spade. He tests speakers and other audio equipment and tells you what he thinks based on TEST data. If you don't believe him or trust him, that is OK. But, he does all this for FREE. Danny's problem is summed up fairly quickly, he wants to play in the engineering field but does not have the education to do so. Back when he started he could get away with it but the field has moved on leaving him behind. He constantly makes reference to his thousands of A/B tests that are not good for what he is using them for. So, he is wrong thousands of times and doesn't know it. He makes provably false claims all the time. His videos are full of them every time. But to people with no experience or knowledge it all sounds legit. Danny just does NOT have the education to properly know what he doesn't know. Saying there are two sides of the issue Amir vs Danny is incorrect, there is an engineer with a provable knowledge base in the field and a speaker DIY tinkerer. You can't compare the two at all.

 

[Ageve]

At 28:18 he actually shows a measurement without smoothing applied.

He says:

Notice how jagged it is all across the top end. That's where the wavelength starts getting short, and the wavelengths will start reflecting of off things (?), and it causes little ripples all through there, and it's harder to read what's going on, when you're looking at all these little peaks, because what you really want is the average. You want to see what is the level ... I don't need to see every little wiggle, because you can't adjust for those. You can't go in and say "man there's one there, and one there..." You can't change that.

He seems to think that those ripples are caused by the speaker, but they are most likely caused by reflections from the mic stand and/or speaker stand.