YG Acoustics Factory Tour

[bolserst]

As an engineer, I have read with interest the resent series of full page adds in Stereophile showing technical comparisons between YG Acoustics products and competitors. Last week I found myself in Denver with a free afternoon and gave YG Acoustics a call to see if they allowed tours of their factory. Not only do they but Yoav, the designer, would be available to talk to after the tour.

The state of the art CNC milling machine and assembly techniques would not have looked out of place in the Lockheed Martin aircraft factory back home in Fort Worth. It was highly cool to see the precision with which the cabinets were assembled, and the attention to detail inside and out. The highlight for me though was getting to sit down with Yoav and talk about his designs goals, and some of the unique things they do to achieve them.

From the get-go, it was obvious that Yoav was extremely knowledgeable(and opinionated) about the loudspeaker industry. One might expect this from most any audio engineer. What was refreshing to me, though, was how open and honest he was about his choices in materials, drivers, and geometry that make up their unique products.

There were a few things considered YG Acoustics proprietary technologies. For instance, they use absolutely no damping material in the midrange and woofer cabinets. Yoav feels that the enclosure should act like a perfect airspring, not a lossy spring. So, damping materials are ruled out. Yet somehow he has managed to eliminate the internal standing waves without the damping material. He would only say that “special pieces” are added which target the specific standing wave frequencies. He also mentioned that only once the enclosure was made of extremely stiff aluminum could this technique work. In any case, there are no signs of standing waves in the cabinet when looking for discontinuities in either the impedance curves or the frequency response. And, the driver impedance peak is actually highy in the enclosure than in free air. This low-loss (no-loss?) enclosure really adds life to recorded music. In their demo room I was stunned by the dynamics, especially the leading edge of plucked strings, felt just like you were standing next to the musician.

Of course the imaging was first rate as well. Yoav spent some time discussing the goals of his unique crossover topology; steep slopes while matching phase between the woofer and tweeter throughout the overlap region. This way the drivers are always moving in the some direction. He described it as kind of a cross between conventional 3rd order and 4th order. The wave guide(well, Yoav did not like to call it a wave guide) is used to match the directivity between the bottom end of the tweeter response and the upper end of the woofer response. As best I could tell, the wave guide used straight side walls and was perhaps 1” deep. Machined in house from solid aluminum of course.

The image floated completely free of the speakers. There was no extraneous noises coming from the enclosures to draw your attention away. While playing music quite loudly, I walked up and placed an ear firmly to the sidewall of the midrange enclosure. Nothing. I didn’t hear anything; I didn’t feel anything. Yoav mentioned that less than 1% of the internal sound pressure escapes thru the enclosure walls; the majority of this is thru the back where it is less intrusive. I guess the ¾” thick aluminum walls are doing their job! Speaking of the aluminum walls, I had wondered how they assembled the enclosures without any visible fasteners. Well, it is basically a box inside of a box. The inner box is screwed together from the outside. Then the panels of the outter box our screwed on from inside the inner box. Pretty clever. Oh, placing an ear to the woofer enclosures and a very, very slight vibration could be felt but nothing heard.

As an engineer I was impressed with these speakers. As a DIY guy, I was humbled.
Many times I will see something one of the hi-end manufacturers are doing and try to emulate them in my own DIY version. In the case of YG Acoustics I’m not sure there is any of their design elements that I could incorporate without significant investment in machining equipment. I may have another go at using a waveguide. My previous efforts always resulted in a very forward sound-stage without much depth. Besides that, I am highly curious as to how they are able to remove the standing waves in the enclosure without damping material. I just may have to give it a try with a simple aluminum test box. I have a few ideas bouncing around in my head…

So, if you are ever in Denver and have a few free hours I’d highly recommend giving YG Acoustics a call. I would definitely consider them one of the “good guys” in the high-end loudspeaker world. You will certainly come away with a new appreciation for what is possible in our hobby of loudspeaker design.

[cuibono]

Hm, interesting stuff. I would never have though to call them - I might sometime now. Thanks!

[bolserst]

One other minor detail that just came to mind was that the subwoofer amplifier they use is custom built for them by Hypex. Of course the amplifier is housed in a completely sealed section of the woofer enclosure.

[sdclc126]

They seem to be well designed speakers - nothing really radical just good applications of current technologies.

[Patrick Bateman]

Originally Posted by bolserst

:: snip ::

There were a few things considered YG Acoustics proprietary technologies. For instance, they use absolutely no damping material in the midrange and woofer cabinets. Yoav feels that the enclosure should act like a perfect airspring, not a lossy spring. So, damping materials are ruled out. Yet somehow he has managed to eliminate the internal standing waves without the damping material. He would only say that “special pieces” are added which target the specific standing wave frequencies. He also mentioned that only once the enclosure was made of extremely stiff aluminum could this technique work. In any case, there are no signs of standing waves in the cabinet when looking for discontinuities in either the impedance curves or the frequency response. And, the driver impedance peak is actually highy in the enclosure than in free air. This low-loss (no-loss?) enclosure really adds life to recorded music. In their demo room I was stunned by the dynamics, especially the leading edge of plucked strings, felt just like you were standing next to the musician.

I've seen the speakers and listened to them at the Rocky Mountain Audio Fest. They're attractive, but the sound wasn't particularly memorable. This isn't a knock by the way - I've found that most VERY good speakers sound like nothing at all. Typically the speakers that impress in the short term grow fatiguing in the long term. And the same holds true for amplifiers and electronics.

Anyways, the woofers and the tweeters didn't appear to be anything more than off-the-shelf units from Scan Speak and Vifa. The cabinets ARE something special though.

Also, his comment that the impedance peak of the woofer went up inside the cabinet - that's normal. Standard operating procedure for a loudspeaker enclosure.

Originally Posted by bolserst

Of course the imaging was first rate as well. Yoav spent some time discussing the goals of his unique crossover topology; steep slopes while matching phase between the woofer and tweeter throughout the overlap region. This way the drivers are always moving in the some direction. He described it as kind of a cross between conventional 3rd order and 4th order. The wave guide(well, Yoav did not like to call it a wave guide) is used to match the directivity between the bottom end of the tweeter response and the upper end of the woofer response. As best I could tell, the wave guide used straight side walls and was perhaps 1” deep. Machined in house from solid aluminum of course.

The image floated completely free of the speakers. There was no extraneous noises coming from the enclosures to draw your attention away. While playing music quite loudly, I walked up and placed an ear firmly to the sidewall of the midrange enclosure. Nothing. I didn’t hear anything; I didn’t feel anything. Yoav mentioned that less than 1% of the internal sound pressure escapes thru the enclosure walls; the majority of this is thru the back where it is less intrusive. I guess the ¾” thick aluminum walls are doing their job! Speaking of the aluminum walls, I had wondered how they assembled the enclosures without any visible fasteners. Well, it is basically a box inside of a box. The inner box is screwed together from the outside. Then the panels of the outter box our screwed on from inside the inner box. Pretty clever. Oh, placing an ear to the woofer enclosures and a very, very slight vibration could be felt but nothing heard.

As an engineer I was impressed with these speakers. As a DIY guy, I was humbled.
Many times I will see something one of the hi-end manufacturers are doing and try to emulate them in my own DIY version. In the case of YG Acoustics I’m not sure there is any of their design elements that I could incorporate without significant investment in machining equipment. I may have another go at using a waveguide. My previous efforts always resulted in a very forward sound-stage without much depth. Besides that, I am highly curious as to how they are able to remove the standing waves in the enclosure without damping material. I just may have to give it a try with a simple aluminum test box. I have a few ideas bouncing around in my head…

So, if you are ever in Denver and have a few free hours I’d highly recommend giving YG Acoustics a call. I would definitely consider them one of the “good guys” in the high-end loudspeaker world. You will certainly come away with a new appreciation for what is possible in our hobby of loudspeaker design.

This part is something that I agree with 110%. I see a lot of people going nuts with the construction of their subwoofers, when re-radiation from the enclosure of a midrange can *really* create false imaging cues, and even blips in the frequency response. It's a very real problem.

Here's a pic of an older model - you can see this these are off-the-shelf parts in a very nice enclosure, with a healthy dollop of solid engineering. Nothing wrong with that at all.

[gainphile]

The enclosure would be very stiff indeed, but wouldn't the sound in the enclosure bounce back out to the thin speaker cone anyway?

The engineering details and execution are to be admired, but the old acoustic problems would still be there I think.

[Patrick Bateman]

Originally Posted by gainphile

The enclosure would be very stiff indeed, but wouldn't the sound in the enclosure bounce back out to the thin speaker cone anyway?

The engineering details and execution are to be admired, but the old acoustic problems would still be there I think.

The really obnoxious imaging cues come from panels vibrating which are a distance from the midrange. For instance, the side panel of an enclosure radiating a fraction of a millimeter.

Because the panel is so large, even a fraction of a millimeter will make an audible difference.

Measuring the loudspeaker at various angles helps, since the sound will be directional, due to the size of the panel.

If the sound is simply re-radiating back through the cone, there will be little effect on the image, because it's still radiating from the same point in space (the speaker.)

There *would* be an effect on articulation however.

[bolserst]

Originally Posted by Patrick Bateman

[FONT="Verdana"][SIZE="2"]

I've seen the speakers and listened to them at the Rocky Mountain Audio Fest. They're attractive, but the sound wasn't particularly memorable. This isn't a knock by the way - I've found that most VERY good speakers sound like nothing at all. Typically the speakers that impress in the short term grow fatiguing in the long term. And the same holds true for amplifiers and electronics.

Anyways, the woofers and the tweeters didn't appear to be anything more than off-the-shelf units from Scan Speak and Vifa. The cabinets ARE something special though.

Also, his comment that the impedance peak of the woofer went up inside the cabinet - that's normal. Standard operating procedure for a loudspeaker enclosure.


This part is something that I agree with 110%. I see a lot of people going nuts with the construction of their subwoofers, when re-radiation from the enclosure of a midrange can *really* create false imaging cues, and even blips in the frequency response. It's a very real problem.

Hmmm...I've never been able to get the impedance peak of a midrange or mid-woofer to exceed the free-air peak, even with minimal damping material...just enough to tame the standing waves.

I totally agree about the importance of minimizing re-radiation from the midrange enclosure. That is one of the biggest things I notice when A-B testing between a panel speaker and a box speaker; by comparison, the box speaker allows seems to have a haze of sound around it and at times the extraneous re-radiation pulls your attention away from the image.

Do you happen to know how long ago that picture is from? All the drive units I saw definitely were based on Scan Speak units, but each also had some custom modifications.

[bolserst]

Originally Posted by Patrick Bateman

[FONT="Verdana"][SIZE="2"]

Also, his comment that the impedance peak of the woofer went up inside the cabinet - that's normal. Standard operating procedure for a loudspeaker enclosure.

It just dawned on me that my statement about the impedance peak being higher in the box could have been interpreted two ways.
I should have said that the magnitude of the impedance peak was higher in the box than in free air.
This is unusual, in my experience; I've certainly never measured a closed box woofer where this was the case.
As you stated, it is quite normal for the frequency of the impedance peak to increase when the driver is placed in a sealed box.

I just noticed that they have added a PDF file to their website with some measurement details relating to this.
http://www.ygacoustics.com/YG_Acoust...e_Sep_2008.pdf

[Hezz]

Originally Posted by bolserst

As an engineer, I have read with interest the resent series of full page adds in Stereophile showing technical comparisons between YG Acoustics products and competitors. Last week I found myself in Denver with a free afternoon and gave YG Acoustics a call to see if they allowed tours of their factory. Not only do they but Yoav, the designer, would be available to talk to after the tour.

The state of the art CNC milling machine and assembly techniques would not have looked out of place in the Lockheed Martin aircraft factory back home in Fort Worth. It was highly cool to see the precision with which the cabinets were assembled, and the attention to detail inside and out. The highlight for me though was getting to sit down with Yoav and talk about his designs goals, and some of the unique things they do to achieve them.

From the get-go, it was obvious that Yoav was extremely knowledgeable(and opinionated) about the loudspeaker industry. One might expect this from most any audio engineer. What was refreshing to me, though, was how open and honest he was about his choices in materials, drivers, and geometry that make up their unique products.

There were a few things considered YG Acoustics proprietary technologies. For instance, they use absolutely no damping material in the midrange and woofer cabinets. Yoav feels that the enclosure should act like a perfect airspring, not a lossy spring. So, damping materials are ruled out. Yet somehow he has managed to eliminate the internal standing waves without the damping material. He would only say that “special pieces” are added which target the specific standing wave frequencies. He also mentioned that only once the enclosure was made of extremely stiff aluminum could this technique work. In any case, there are no signs of standing waves in the cabinet when looking for discontinuities in either the impedance curves or the frequency response. And, the driver impedance peak is actually highy in the enclosure than in free air. This low-loss (no-loss?) enclosure really adds life to recorded music. In their demo room I was stunned by the dynamics, especially the leading edge of plucked strings, felt just like you were standing next to the musician.

Of course the imaging was first rate as well. Yoav spent some time discussing the goals of his unique crossover topology; steep slopes while matching phase between the woofer and tweeter throughout the overlap region. This way the drivers are always moving in the some direction. He described it as kind of a cross between conventional 3rd order and 4th order. The wave guide(well, Yoav did not like to call it a wave guide) is used to match the directivity between the bottom end of the tweeter response and the upper end of the woofer response. As best I could tell, the wave guide used straight side walls and was perhaps 1” deep. Machined in house from solid aluminum of course.

The image floated completely free of the speakers. There was no extraneous noises coming from the enclosures to draw your attention away. While playing music quite loudly, I walked up and placed an ear firmly to the sidewall of the midrange enclosure. Nothing. I didn’t hear anything; I didn’t feel anything. Yoav mentioned that less than 1% of the internal sound pressure escapes thru the enclosure walls; the majority of this is thru the back where it is less intrusive. I guess the ¾” thick aluminum walls are doing their job! Speaking of the aluminum walls, I had wondered how they assembled the enclosures without any visible fasteners. Well, it is basically a box inside of a box. The inner box is screwed together from the outside. Then the panels of the outter box our screwed on from inside the inner box. Pretty clever. Oh, placing an ear to the woofer enclosures and a very, very slight vibration could be felt but nothing heard.

As an engineer I was impressed with these speakers. As a DIY guy, I was humbled.
Many times I will see something one of the hi-end manufacturers are doing and try to emulate them in my own DIY version. In the case of YG Acoustics I’m not sure there is any of their design elements that I could incorporate without significant investment in machining equipment. I may have another go at using a waveguide. My previous efforts always resulted in a very forward sound-stage without much depth. Besides that, I am highly curious as to how they are able to remove the standing waves in the enclosure without damping material. I just may have to give it a try with a simple aluminum test box. I have a few ideas bouncing around in my head…

So, if you are ever in Denver and have a few free hours I’d highly recommend giving YG Acoustics a call. I would definitely consider them one of the “good guys” in the high-end loudspeaker world. You will certainly come away with a new appreciation for what is possible in our hobby of loudspeaker design.

There is nothing too secret about how the standing wave problem is dealt with. When using aluminum two methods are available both of which could be very effective. You can use a thick slab of aluminum and machine a 3d pattern into the inside surface that will break up the standing waves. Much like the shape of convoluted foam. Because there will be no parallel surfaces in the cabinet. But because the shaping is part of the hard structural material of the cabinet wall it does not absorb energy like foam would. By machining a different shape or pattern into different parts of the wall you are changing the mass and stiffness of different parts of the wall so you can take some control of the resonant behavior of the cabinet panels between the bracing.

However, a less expensive method would probably be to machine a series of threaded bolt holes inside the inner wall and mount a bunch of shaped aluminum parts of various sizes. This could both enhance the structure and change the vibrational nodes of the panel and break up standing waves all at the same time.

A very effective method but difficult and expensive for the DIYer. Since you would need a big mill for doing speaker sized panels. However assembly would be a snap. Some glue and then bolt the thing together. Using this method you could have nearly total control over the resonant behavior of the cabinet and could tune the resonances that you could not get completely rid of.