RSL CG25 Center Speaker Review

[Maiky76]

This is a review, listening tests and measurements of the RSL CG25 center home theater speaker. It is on kind loan from a member and costs US $425.
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This is an unusual design in that the port goes through a path in the back which kind of resembles a very short/truncated transmission channel. Otherwise we have the usual MTM configuration of dual mid-woofers and tweeter. Not much to see on the back other than the useful threaded insert for mounting it to the wall:
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Build quality seems good with nice finish and reasonable weight and solidity.

I was contacting the company regarding another product so while I was at it, I asked them to review the frequency response measurements. They are generally in agreement with the results you are about to see.

Speaker was tested in horizontal configuration as you see above. Reference axis was that of tweeter.

RSL CG25 Center Speaker Measurements
As usual we start with our anechoic frequency response measurements:
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At first glance, the on-axis response looks quite bad. But stepping back, the bass/mid-range simply has too much output. And we have a single resonant peak around 4.6 kHz. We can see the reason for both in the near-field, non-anechoic response of the drivers and port:
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The unusual port design is extending the output all the way up to 500 Hz. The are resonances after that but levels are rather low. Woofers nicely roll off.

Predicted in-room response and early window reflections are messy due to above factors:

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MTM configurations cause the dual drivers to "beam" and as such, lose their side energy at certain frequencies and we see that here as well:
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Some really get narrow and this one looks a bit wider than normal which is good:
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Vertical directivity is wide so if you use the speaker vertically, you don't have this issue:
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The dual drivers plus wideband port response helps a lot with distortion in bass:
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We do have distortion where the resonance was. So to the extent we reduce that peak with EQ, we can also put a bandage on that.

Impedance is typical at 4.2 ohm:
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Here are the waterfall and step responses:

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RSL CG25 Speaker Listening Tests
Objective measurements do not prepare you well for what you first hear from this speaker. First impression is authoritative bass with good balance with highs! I know, how could that be? Well, my first track is always a female track where some bass adds warmth. But where is the high coming from? Well, it is the resonance we have seen in the measurements. I took that down first with EQ and now the tonality shifted to too much bass:

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I then worked backwards and put in the shelving filter to lower the bass, and fill the hole in that region. I then performed and AB and you now much more clearly heard how much extra bass there was without EQ.

With EQ, the performance was superb! This one small speaker could pump out power no matter how loud I cranked my 500+ watt amplifier! The sound was clean, with nice impactful bass and super satisfying! I dare say it was one of the best sounding center speakers I have tested!!!

Mind you, there is not much support for sub-bass but what is there is just a tad distorted. Many small speakers produce highly distorted response there.

Conclusions
One of the benefits of a center speaker is that you almost know that it will be used in a home theater situation with EQ. So why not design it with extra bass response and have the EQ fix that as needed? That seems to be at play here with CG25. With over 90 dB sensitivity in bass and midrange region, you have plenty of dynamic range in reserve. Bring the level down and you reduce distortion. Sure, there is a resonant peak in treble but interestingly, that provided some balanced to extra bass in case someone uses it without EQ.

So what we have here is a design that on purpose (per company) deviates from neutral response, but in a beneficial way when equalized. I always wondered about such an approach: not wasting sensitivity in a speaker and letting it produce the most of what it can, and then fixing with EQ.

For a center speaker where so much energy is directed at in movies, the overall picture is quite positive, pun intended.

I am happy to recommend the RLS CG25 with equalization where it produces superb fidelity and ability to play incredibly loud.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

@amirm are you sure about the EQ settings?
In particular the 410Hz peak, I mean if you tried to compensate the suck out it is more like at 555Hz...

Here is my take on the EQ.

Please report your findings, positive or negative!

The following EQs are “anechoic” EQs to get the speaker right before room integration. If you able to implement these EQs you must add EQ at LF for room integration, that is usually not optional… see hints there: https://www.audiosciencereview.com/...helf-speaker-review.11144/page-26#post-800725


The raw data with corrected ER and PIR:

Score no EQ: 2.9
With Sub: 5.0

Spinorama with no EQ:

• too many issues to list...

Directivity:
Horizontal: stay in front of the tweeter
Vertically +/-10deg

EQ design:

I have generated one EQ. The APO config file is attached.

• The second, labelled Score, starts with the first one and adds the score as an optimization variable.
• The EQs are designed in the context of regular stereo use i.e. domestic environment, no warranty is provided for a near field use in a studio environment although the LW might be better suited for this purpose.

Score EQ Amirm: 2.4
with sub: 4.7

Score EQ Score: 5.2
with sub: 7.2

RSL CG25 APO EQ Score 96000Hz
March012023-140858

Preamp: -1.9 dB

Filter 1: ON HPQ Fc 37.60,    0.00,    0.99
Filter 2: ON PK Fc 167.78,    -5.74,    0.73
Filter 3: ON PK Fc 355.56,    -3.57,    1.76
Filter 4: ON PK Fc 723.34,    -4.00,    5.45
Filter 5: ON PK Fc 896.43,    -3.21,    4.28
Filter 6: ON PK Fc 1387.11,    3.02,    0.52
Filter 7: ON PK Fc 2443.80,    -3.26,    1.51
Filter 8: ON PK Fc 4615.23,    -5.80,    5.04
Filter 9: ON PK Fc 5603.74,    2.73,    6.72

Spinorama EQ Amirm

Spinorama EQ Score

Zoom PIR-LW-ON

Regression - Tonal

Radar no EQ vs EQ score
Nice improvements but start from low...

The rest of the plots is attached.

 

[MZKM]

Note: Rating not designed for center channel speakers.

Preference Rating
SCORE: 3.0
SCORE w/sub: 5.0

Sensitivity: 88.3dB (300Hz-3kHz ; spec: 88dB)
Frequency response: +/- 4.6dB 51Hz-20khz

​

 

[anphex]

Does this speaker even have a crossover? Honestly it looks like a design product with some chassis slapped together, loosely level matched and off to shipping. Not even the port seems take make sense.

 

[sarumbear]

I don't understand how any MTM gets recommended as a center channel.

It should be a blanket "no"

The window is measured to be 36 degrees, which is just shy of the recommended 40 degree viewing window in a HT. This is definitely a good enough spec.

 

[abdo123]

The window is measured to be 36 degrees, which just short of the recommended 40 degree viewing window in a HT. This is definitely a good enough spec.

I guess if you're okay with a -6dB hole with the response.

 

[sarumbear]

I guess if you're okay with a -6dB hole with the response.

Where is that hole within the 36 degree window?

If you are talking about the drop in the 500-600Hz range, @amirm have answered that. After the bass is reduced with a shelf filter the dip is reduced to 4dB, which is then compensated with a notch filter. The speaker is designed to be EQ'ed.

 

[thewas]

Where is that hole within th3 36 degree window?

See the orange 20° curve which represents the border behaviour of a total 40° (±20°) horizontal listening window.

 

[abdo123]

Where is that hole within the 36 degree window?

Maybe you should read what the red line that you're referencing means?

 

[rvsixer]

I'm not sure what to think about a speaker company that says a desired center channel trait is for it to have a "subtle presence". For a channel that averages about ~70% of the bed layer output, I prefer my center channels to be robust :
"*The CG23M can be placed vertically or horizontally and provides the subtle presence desired from a center channel."

 

[sarumbear]

See the orange 20° curve which represents the border behaviour of a total 40° (±20°) horizontal listening window.

Thank you but you are confirming what I am saying. I appreciate if you explain what I’m missing?

 

[sarumbear]

Maybe you should read what the red line that you're referencing means?

It’s on the graph title is t it? What am I missing?

 

[abdo123]

It’s on the graph title is t it? What am I missing?

it says -6db

 

[thewas]

Thank you but you are confirming what I am saying. I appreciate if you explain what I’m missing?

You are welcome, but it is not confirming what you say but what @abdo123 wrote, namely that the yellow 20° curve shows an approximate 6 dB dip (around 1,5 kHz).

 

[sarumbear]

You are welcome, but it is not confirming what you say but what @abdo123 wrote, namely that the yellow 20° curve shows an approximate 6 dB dip (around 1,5 kHz).

Please read my reply to @abdo123 above. After the bass correction shelf filter the dip is reduced to 4dB, which is then further EQ’ed with a notch filter.

The manufacturer has specifically designed a speaker that should be EQ’ed hence we should review it as EQ’ed. as this is a centre speaker, it is normal to assume that it will be we used with an AVR and they almost all have an EQ facility. Otherwise it is similar to testing an active speaker with its DSP disabled.

 

[abdo123]

Please read my reply to @abdo123 above. After the bass correction shelf filter the dip is reduced to 4dB, which is then further EQ’ed with a notch filter.

That's not how speaker directivity works. you either have a peak on-axis with this speaker or a dip off-axis. there is no middle ground with EQ.

The manufacturer has specifically designed a speaker that should be EQ’ed hence we should review it as EQ’ed. as this is a centre speaker, it is normal to assume that it will be we used with an AVR and they almost all have an EQ facility. Otherwise it is similar to testing an active speaker with its DSP disabled.

EQ will not fix the MTM radiation, and the manufacturer did not provide the filters that Amir used nor the spinorama Amir used to make the filters.

So yeah I don't agree with your conclusion.

 

[rvsixer]

The manufacturer has specifically designed a speaker that should be EQ’ed hence we should review it as EQ’ed. as this is a centre speaker, it is normal to assume that it will be we used with an AVR and they almost all have an EQ facility. Otherwise it is similar to testing an active speaker with its DSP disabled.

Unless I am reading it wrong, the EQ being discussed to apply, is to tame the bass response. The narrowing of the horizontal dispersion occurs well above that range, so the -6dB response dip at +/- 18 degrees still applies, EQ or not?

 

[jbattman1016]

Being an owner of a CG25, it works great with or without EQ, but this is totally just based on my limited experience with 3-way speakers

Honestly, if I could do it all over, I would use the CG25s for L/R and get one of the Emotiva centers.

 

[PeteL]

Please read my reply to @abdo123 above. After the bass correction shelf filter the dip is reduced to 4dB, which is then further EQ’ed with a notch filter.

The manufacturer has specifically designed a speaker that should be EQ’ed hence we should review it as EQ’ed. as this is a centre speaker, it is normal to assume that it will be we used with an AVR and they almost all have an EQ facility. Otherwise it is similar to testing an active speaker with its DSP disabled.

You Get that there's a dip at 20 degree at 1.5kHz that is not present on axis right? (or to be clear, is 6 dB less pronounced). Your answer suggest that you are talking about something else than directivity induced frequency response error.
Edit, ain't it actually 8 dB?

 

[Billy Budapest]

Amir reviews subwoofers? Anyways, Audioholics already measured it.

Why not Amir review it?

Audioholics measures lots of things. But this is not the Audioholics forum.

 

[thewas]

Please read my reply to @abdo123 above. After the bass correction shelf filter the dip is reduced to 4dB, which is then further EQ’ed with a notch filter.

The manufacturer has specifically designed a speaker that should be EQ’ed hence we should review it as EQ’ed. as this is a centre speaker, it is normal to assume that it will be we used with an AVR and they almost all have an EQ facility. Otherwise it is similar to testing an active speaker with its DSP disabled.

You can fill it even completely with a EQ but that doesn't change the directivity problem with the central listener at 0° having in that case a 6dB peak.
Directivity problems cannot be solved via EQ.