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RSL CG4, CG24, and Speedwoofer 10 Measurements and Analysis

By

by. Gene DellaSala

I heard such great things about these little speakers from Theo that it inspired me to check out a pair for myself.  I selected the CG4's to do some listening tests and pull a few measurements.  You can see our YouTube Video to get my impressions of the sound and build quality of these speakers.

Listening Window

RSL CG4 Listening Window Response (1 meter spliced GP at 500Hz)

I placed the CG4 speaker on a plateau stand with the tweeter at the bottom and measured it in-room 1 meter away.  The listening window response is an average of on-axis, +-15, +-30 deg horizontal and +- 10deg vertical which is a total of seven measurements.  I then measured the speaker using groundplane technique spliced into this curve at and below 500Hz to help remove the room influences.  As you can see the CG4 exhibited great linearity. The -3dB point looks to be just below 100Hz as stated by RSL.  Sensitivity measured about 85dB (@ 1 meter and 2.83V) which is 3dB lower than the manufacturer specified.  My listening tests revealed these speakers have quite an energenic top end.  I personally preferred listening to them with the tweeter above the woofer in a nearfield situation with a very slight toe-in. 

Frequency Response Grille on

RSL CG4 Frequency Response

Grille on: Blue ; Grille off: Red

I measured a very slight difference in frequency response with and without the grilles on.  There is a little less output in the 5-7kHz region with the grille on which may be a desirable attribute for those wanting to tone down the top end of the speaker just a touch.

Impedance Curve

RSL CG4 Impedance and Phase

The CG4 measured a nominal 8 ohms just like RSL states, never dropping below 7 ohms (6.4 ohm min per IEC requirement).  However you can see the box is a little too small for the driver with the asymmetric peaks between the saddle point.  To RSL's credit, didn't hear any ill effects in bass.  However,  in my opinion,  a speaker this small should be sealed since a port can't do a whole lot in this scenario. 

Speedwoofer 10

Listed below is the CEA-2010 SPL data* which tells you how loud the Speedwoofer 10 can play within a set limit in distortion criteria per the standard.

2M CEA 2010 RMS Data:

63 Hz:                   111.1 dB 
50 Hz:                   111.1 dB 
40 Hz:                   108.0 dB 
31.5 Hz:               104.7 dB 
25 Hz:                   98.1 dB
20 Hz:                   90.7 dB

* CEA2010 data courtesy of Brent Butterworth of Hometheaterreview.com

Based on the CEA2010 data, the Speedwoofer sub meets our Medium Bassaholic Room size rating with a good degree of margin.

 

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Recent Forum Posts:

JPyman325 posts on January 01, 2016 10:52
An update on this amazing systems sub woofer. Last night while watching fireworks with our neighbors we were making sure that neither of could hear our outdoor speakers. He says the only thing he can hear is the neighbor on our other side son playing his new bass. Well its actually my sub watching movies. My HT is upstairs over the garage and there is probably 50 feet between our house and theres -
JPyman325 posts on December 31, 2015 09:20
I would suggest giving RSL a call and talk to either Joe or his dad Roger who designed the speakers. These are one the best speakers I have heard in a long time even off-axis listening as in my bedroom with bookshelf. One of the most impressive is how good these speakers sound at each volume level. My old Def Tech's (1990's) needed power and volume to really come a live. My Mirage's also had their sweet spot. I have not found a volume that these don't sound good but loud is always better.

The speed woofer is amazing a good tight bass for music and with enough power to feel the movie throughout my house. My HT is upstairs above the garage and my wife feels the vibration in our bedroom - other side of the house downstairs and our house is not small (nor large unless you live in New York).
TLS Guy posts on December 31, 2015 09:05
ski2xblack, post: 1111009, member: 9107
That impedance curve looks a bit like that of a speaker with an aperiodic port that needs a bit more stuffing. Those rsl cabs are interesting. They remind me somewhat of Atlantic Technology's HPAS cabs. Although AT's goal was extension, both have unconventional enclosures that feature some sort of novel hybrid/truncated/reverse taper transmission lines with side chamber, and from the looks of it they must damp the active driver a bit differently than by-the-numbers bass reflex. I would actually have been surprised to see the classic symmetric impedance peaks Gene expected.

I have been looking at this. It is not a reverse taper TL. If it were the start of the pipe would be widest. It is more like a horn that is too short. There is an expansion box, throat, and another expansion, just like a horn would have. Then there is that port.

The impedance curve looks like a that of an incorrectly tuned QB4 box. The 3 db point is around 100 Hz and the roll off is fourth order like a ported box would.

I'm not at all convinced that internal contributes anything but bracing. I would like to see the comparison of the same drivers and crossover in a properly deigned QB4 box. My feeling is it would be superior.

The speaker sounds good because the crossover seems spot on and the drivers are perfectly integrated.

As for the bass loading, it seems a mish mash of a too short TL with expansion and taper of a horn and then an attempt as mass loading with a port. Pending further information and data from the company, I'm not impressed with this loading arrangement.

The Speedwoofer on the other hand at first glance looks more promising. Although F3 is fairly high, it is rolling off second order, like a TL would.

I would like to see more measurements of that, and details.

I have tried various configurations over the years to try and reduce the real estate of TLs, including mass loading them with ABRs. The only ones any good were labyrinths. I suspect if that GL4 where a labyrinth it would be much more promising as far as the low end is concerned.
The price would be higher as there would be a lot more internals. However I think the 3db point would be lower and roll off second order, with more low bass, and low Q to boot.
TLS Guy posts on December 31, 2015 08:56
ski2xblack, post: 1111009, member: 9107
That impedance curve looks a bit like that of a speaker with an aperiodic port that needs a bit more stuffing. Those rsl cabs are interesting. They remind me somewhat of Atlantic Technology's HPAS cabs. Although AT's goal was extension, both have unconventional enclosures that feature some sort of novel hybrid/truncated/reverse taper transmission lines with side chamber, and from the looks of it they must damp the active driver a bit differently than by-the-numbers bass reflex. I would actually have been surprised to see the classic symmetric impedance peaks Gene expected.

I have been looking at this. It is not a reverse taper TL. If it were the start of the pipe would be widest. It is more like a horn that is too short. There is an expansion box, throat, and another expansion, just like a horn would have. Then there is that port.

The impedance curve looks like a that of an incorrectly tuned QB4 box. The 3 db point is around 100 Hz and the roll off is fourth order like a ported box would.

I'm not at all convinced that internal contributes anything but bracing. I would like to see the comparison of the same drivers and crossover in a properly deigned QB4 box. My feeling is it would be superior.

The speaker sounds good because the crossover seems spot on and the drivers are perfectly integrated.

As for the bass loading, it seems a mish mash of a too short TL with expansion and taper of a horn and then an attempt as mass loading with a port. Pending further information and data from the company, I'm not impressed with this loading arrangement.

The Speedwoofer on the other hand at first glance looks more promising. Although F3 is fairly high, it is rolling off second order, like a TL would.

I would like to see more measurements of that, and details.

I have tried various configurations over the years to try and reduce the real estate of TLs, including mass loading them with ABRs. The only ones any good were labyrinths. I suspect if that GL4 where a labyrinth it would be much more promising as far as the low end is concerned.
The price would be higher as there would be a lot more internals. However I think the 3db point would be lower and roll off second order, with more low bass, and low Q to boot.
ski2xblack posts on December 31, 2015 02:17
KEW, post: 1108809, member: 41838
In the measurement section, Gene wrote:

The CG4 measured a nominal 8 ohms just like RSL states, never dropping below 7 ohms (6.4 ohm min per IEC requirement). However you can see the box is a little too small for the driver with the asymmetric peaks between the saddle point. To RSL's credit, didn't hear any ill effects in bass. However, in my opinion, a speaker this small should be sealed since a port can't do a whole lot in this scenario.


Did either of you try sealing the port to see if it affected the sound quality? That would be interesting to establish since the port is designed to reduce resonance rather than be a source of added sound (as I understand it).

That impedance curve looks a bit like that of a speaker with an aperiodic port that needs a bit more stuffing. Those rsl cabs are interesting. They remind me somewhat of Atlantic Technology's HPAS cabs. Although AT's goal was extension, both have unconventional enclosures that feature some sort of novel hybrid/truncated/reverse taper transmission lines with side chamber, and from the looks of it they must damp the active driver a bit differently than by-the-numbers bass reflex. I would actually have been surprised to see the classic symmetric impedance peaks Gene expected.
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