Audiovector M1 Super Spinorama measurements (CTA-2034)

[Ageve]

Here are some measurements of the Audiovector M1 Super bookshelf speaker. The MSRP was ~1000 USD / pair back in 2002.

There are three ports at the back, but only two are bass ports. The top one is for the tweeter:

Specifications:

Size (WHD): 20 x 35 x 27 cm (7.87 x 13.78 x 10.63 inches)
Weight: 6 kg / speaker
Sensitivity: 88 dB
Impedance: 8 Ohms
Frequency response: 50 Hz - 25 kHz
Recommended distance from rear wall: 15-25 cm
Recommended degrees of toe in: 2-4


My measurements are quasi-anechoic, with nearfield port+woofer (corrected for baffle edge diffraction) merged with gated measurements at 1m distance. 1m vs 2m comparison is attached (I have vertical off-axis comparisons as well. Let me know if you'd like to see them).

I have also attached impulse response, ETC, step response and phase to comply with VituixCAD requirements.


There's no recommendation for listening height in the user manual, but they do provide this info:

Be sure to choose loudspeaker cables, which are fast, clean, open
and musical sounding. (Some cables slow down the sound. This is a
type of distortion). Please consult your Audiovector dealer.

Joking aside, I ended up measuring 30 mm below tweeter axis (smoothest response).


Here's the result:

On-axis response is ok up to ~3 kHz, but then it goes downhill. ER and sound power looks better.

Early reflections:

The interesting looking rear wall bounce is caused by the rear tweeter port.

Estimated in-room response:

Horizontal directivity:

This also looks "interesting" because of the tweeter port:

Vertical directivity:

On-axis response:

Mostly within +/- 1.5 dB up to 3 kHz:

Distortion:

THD is very low, except for something going on with the tweeter at 6 kHz. Still below 1% though.

The peak remains at 76dB / 1m:

Nearfield:

The two 30mm ports are tuned quite low.

Rear tweeter port looks, well, interesting.

Finally, here's a comparison with a measurement by the Swedish magazine Hifi & Musik, from 2003:

I plotted the graph after finishing all my measurements, and was surprised by how similar the tweeter response is. It looks like they measured 30 mm below tweeter axis as well, and it also confirms that my 23 year old speaker is working just fine.

Subjective opinion:

It doesn't sound too bad, but it's a bit like two speakers in one. Bass and mids are quite neutral, but there's something going on with the tweeter. It doesn't sound bright, but a bit harsh and sometimes "plastic", or lacking detail.

Midrange separation and detail is ok, and bass/mid distortion is low, even at high volume (no gurgling sound on female vocals when there's a lot of bass in the recording). Soundstage is quite flat. I don't know why, but it made me think of 2D movies converted to 3D.

 

[Karmacoma]

Thanks for the review!

 

[NotInYourHead]

Baffling design choice with the rear tweeter "port". Instead of 2 small, too short ports and a midbass hump, the designer could've used the useless tweeter port and ended with better bass, highs and less distortion at the same time

What would happen if you jam polyfill inside the tweeter port or block it completely?

EDIT: I noticed that the woofer is not cut more aggressively at the crossover point with the tweeter. The result is a three-way battle between the woofer, tweeter and "port". I'm half surprised the FR didn't turn out disastrous.

EDIT 2: I found some details regarding the speaker construction and the rationale for placing a port behind the tweeter:

"Bulletproof" faceplate - two plates of MDF, which is laid between the polymer layer damping; resulting thickness of the front of the sandwich - under 30 mm. Housing strengthened horizontal brace; absorber within reasonable minimum; head screwed on. Crossover - the second filter (HF) and the first (LF/MF) orders. Are located on the rear panel are two vented port and the output is not related to the volume of low-clearance tube waveguide, where "soft" radiation attenuates the inner surface of the membrane tweeter, which ensures the symmetry of the wave load on the diffuser; this radiation falls into the waveguide through a hole in the magnet, foamed plastic cork (the proprietary SEC). Socket terminals unusually turned "head-up", but the problems of no.

 

[Ageve]

What would happen if you jam polyfill inside the tweeter port or block it completely?

Good idea. This is how it performs with the port blocked:

A bit smoother, but no meaningful difference, at least not on-axis.

Bass ports plugged (tweeter port open):

I measured the second speaker today as well:

It's actually a bit smoother up to 5 kHz, but the difference is small, and the one I used for the spin is more similar to the one measured by Hifi & Musik.

EDIT: I noticed that the woofer is not cut more aggressively at the crossover point with the tweeter. The result is a three-way battle between the woofer, tweeter and "port". I'm half surprised the FR didn't turn out disastrous.

You're probably right.

This is the near-field response with bi-wire terminals disconnected (second speaker used here):

And here's the 1m response:

 

[amirm]

Nice. Promoted to home page.

 

[kemmler3D]

The craziness at 5-6khz is concerning, I'm surprised it doesn't sound worse or have a worse PIR. Not as bad as I expected, but also not surprised that tweeter ports haven't caught on...

 

[Timcognito]

Nice presentation, solid match to the H&M measurements and pin to the review page, well done.

 

[DSJR]

What the heck is going on at 4kHz? I was taught very early on that peaks are far more audible in a nasty way than subtle dips and this one couldn't have been at a worse place, where the ear is most sensitive to such things!

I wonder if the bass unit is run wide open and the tweeter has little more than a cap feeding it to stop low frequencies blowing it?

 

[Ageve]

What the heck is going on at 4kHz? I was taught very early on that peaks are far more audible in a nasty way than subtle dips and this one couldn't have been at a worse place, where the ear is most sensitive to such things!

I wonder if the bass unit is run wide open and the tweeter has little more than a cap feeding it to stop low frequencies blowing it?

In the 1m measurement above (woofer disconnected), it looks like 6dB/octave for the tweeter. I'll do a teardown later.

Woofer response is rough above 3 kHz, but at least it looks like it has a crossover:

Minimal listening/measuring distance (on-axis) is around 50 cm:

 

[BossBunos]

Thanks! Nice to see member reviews more often. Can I ask how you generated the "stereophile like" horizontal directivity plot?

 

[Ageve]

Thanks! Nice to see member reviews more often. Can I ask how you generated the "stereophile like" horizontal directivity plot?

In VituixCAD, right-click on the directivity graph, select waterfall, horizontal plane and show +/- 90 deg.

 

[xanalog]

In the 1m measurement above (woofer disconnected), it looks like 6dB/octave for the tweeter. I'll do a tear-down later.
Woofer response is rough above 3 kHz, but at least it looks like it has a crossover:

@Ageve,
Thank you for the review.
Would it be beneficial to perform some impedance sweeps on both speakers before you tear-down one of them?

 

[eddantes]

When you do a teardown - if you can (shove a phone in there) - please take a picture of the crossover. As for the 6K thing - woofer breakup? IR looks decent.

 

[Maiky76]

Thanks for the review!

As usual great effort.
Please don't change the format of the data... Choose one and stick with it.
It will save me quite some time.


Here is my take on the EQ.
Please report your findings, positive or negative!


For the score rational your journey starts here
Explanation for the sub score
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.

The raw data with corrected ER and PIR:

Score no EQ: 4.4
With Sub: 6.7

Spinorama with no EQ:

• smiley face tuning
• Not smooth
• some significant directivity errors

EQ design:
I have generated two EQs. The APO config files are attached.

• The first one, labelled, LW is targeted at making the LW flat
• 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 LW: 5.9
with sub: 7.8

Score EQ Score: 6.6
with sub: 8.3

Audiovector M1 Super APO EQ LW 96000Hz
September292025-140912

Preamp: -3.00 dB

Filter 1: ON HPQ Fc 35.0 Hz Gain 0.00 dB Q 1.35
Filter 2: ON PK Fc 103.7 Hz Gain -4.64 dB Q 1.64
Filter 3: ON PK Fc 754.5 Hz Gain -2.62 dB Q 1.72
Filter 4: ON PK Fc 1780.3 Hz Gain -1.94 dB Q 4.88
Filter 5: ON PK Fc 3748.8 Hz Gain -3.16 dB Q 5.00
Filter 6: ON PK Fc 5032.3 Hz Gain 1.79 dB Q 1.90
Filter 7: ON PK Fc 12703.5 Hz Gain -4.35 dB Q 1.28


Audiovector M1 Super APO EQ Score+ 96000Hz
September292025-140912

Preamp: -3.00 dB

Filter 1: ON HPQ Fc 35.0 Hz Gain 0.00 dB Q 1.36
Filter 2: ON PK Fc 101.7 Hz Gain -4.14 dB Q 1.28
Filter 3: ON PK Fc 750.5 Hz Gain -2.35 dB Q 1.52
Filter 4: ON PK Fc 1766.8 Hz Gain -2.21 dB Q 2.26
Filter 5: ON PK Fc 3625.3 Hz Gain -4.50 dB Q 4.07
Filter 6: ON PK Fc 3468.8 Hz Gain 1.61 dB Q 2.65
Filter 7: ON PK Fc 11739.8 Hz Gain -5.05 dB Q 1.28

Spinorama EQ LW

Spinorama EQ Score

Zoom PIR-LW-ON

Regression - Tonal

Radar no EQ vs EQ score
Some improvements?

 

[skankhobag]

This is a rather odd and somewhat compromised design. Fortunately, giant tweeter ports never became a thing.

 

[Orion76]

Some cables slow down the sound.

lol

 

[DanielT]

Thanks for the test Ageve.

So if I interpret it correctly - or am I seeing it wrong - only around 73 dB sensitivity? I suspect that you measured with input voltage of 2.83 V?
Can that really be true? I mean more am I reading it right? Such a big difference vs. manufacturer's spec: Sensitivity: 88 dB
Or are you measuring in some other way that makes it around 73 dB sensitivity?

By the way, with another tweeter and or crossover maybe it would have been a really good speaker. There is potential. You say, among other things:
THD is very low, except for something going on with the tweeter at 6 kHz. Still below 1% though.

 

[SoySalsaPicante]

How bright is this speaker?

 

[Bob101]

It turns out there might be a reason why tweeters generally are housed in an enclosure of some kind and not bare-backed. It's useless at best.
Otherwise: not bad actually. Also: not cheap, especially in 2002. I wish it weren't, but it been a while since then...

 

[Ageve]

Here's a teardown:

30 mm baffle
2x 30mm ports

Tweeter port:

Inside tweeter port:

Thanks for the test Ageve.

So if I interpret it correctly - or am I seeing it wrong - only around 73 dB sensitivity? I suspect that you measured with input voltage of 2.83 V?
Can that really be true? I mean more am I reading it right? Such a big difference vs. manufacturer's spec: Sensitivity: 88 dB
Or are you measuring in some other way that makes it around 73 dB sensitivity?

Yes, I'm measuring at a lower level (after confirming that the frequency response is identical).

Sensitivity at 1 kHz (2.83v using a simple Fluke 115) is 87.5 dB / 1m using RTA in REW (confirmed at 30cm distance, 98dB), and 87.2 dB / 1m using a UNI-T SPL meter.

It's close to the spec, 88 dB.

How bright is this speaker?

It's a bit bright, but also lacks treble detail. S-sounds are sometimes harsh, but it doesn't sound horrible. Just "meh".

Some cables slow down the sound.

lol

More from the manual:

All Audiovector can either be bi- or tri-wired. The advantages of
multiple cables are: Better soundstage, more inner detail and a cleaner sound.