Audio Pro Addon T14 Spinorama measurements

[Ageve]

Here are some measurements of the Audio Pro Addon T14.

I don't know if Audio Pro are sold outside Europe, but it's a Swedish brand founded in 1978. This speaker is powered but not active (passive crossover). It was on sale for ~189 USD/pair (1990 SEK) before being discontinued a few years ago.

I measured the right speaker (the one without amplifier).

The measurements are quasi-anechoic (near-field port+woofer measurements corrected for baffle edge diffraction, combined with gated outdoor measurements at 1m distance, 5ms window). Merged at 400 Hz.

Since the speaker has tone controls, I started by measuring the tweeter response with all settings. I ended up using tweeter level 7 (and bass level 7) to get the flattest response.

It turned out to be close to the default setting of 6.

Here are the results:

The tweeter behaviour is a bit strange. From 10-12 kHz there's a change in directivity, but above 12 kHz it's almost a flat line. It looks extra weird in the polar maps.

I actually thought something was wrong with the measurements and/or playback of the test signal, so I re-measured the speaker (the whole spin) using 44.1 KHz instead of 96 kHz (to see if it could be caused by the speaker not supporting 24/96 properly (Toslink). The results were identical though, and I ended up using the second spin. That's why it's limited to 20 kHz.

The near-field port response is rough, and the woofer response is also a bit jagged. I'm pretty sure it's caused by cabinet resonances. It feels cheaply made and "hollow".

It matches the peak/uneven response in the quasi-anechoic response (800 Hz - 1.6 kHz).

Horizontal directivity:

Vertical directivity:

Distortion:

Distortion looks ok at > 150 Hz, even at 90 dB SPL. Below is another story, with 10% distortion at 100 Hz.

I did't measure at higher SPL since the port was already making a lot of noise, and the woofer was moving alot.


My subjective impression is that it has a lot of bass for it's size, and it goes deeper than many other small speakers. The bass distortion is quite high though.

As for the overall sound:

No, I'm not comparing it to the Chernobyl disaster. It's not that bad.

The cabinet is audibly resonant though. The bass is impressive for it's size, but a bit muddy. The treble peak causes sharp "s" sounds.

 

[Ageve]

Here's a teardown.

The walls are made of 8 mm MDF (0.3 inches), and the bottom wall for the port looks like it's masonite or something. Very thin.

The crossover would make Danny Richie happy though. No sand cast resistors. In fact, no resistors at all. Even better, I guess?

I did a quick bodge-job, and added some bracing + replaced the damping material just to see if it would make any difference. It's obviously not a permanent solution, and it wouldn't even fit in the powered speaker.

It smoothed out the peaks, and the highest one is reduced by almost 3 dB, but the overall level is about the same.

The woofer response is almost identical (maybe a little smoother):

Finally, I plugged the port. It didn't do anything to the woofer response > 200 Hz:

edit: I'm listening to it now, and it actually made a noticable difference.

The bass is less muddy and "resonant". Maybe it's just my imagination, but still.

 

[DanielT]

Good job Agave!

Audio Pro Addon T14 was sold by one of Sweden's largest department store chains in home electronics and white goods, so many of them have probably been sold. They are now often sold on the used market for around $100.

Ageve it would be really interesting to see the results if you measured a pair of cult classic A4.14.

Audio Pro was ahead of its time. An active speaker with Ace Bass technology:

Our story - Audio Pro - Play Nice

www.audiopro.com

_____

If the A4.14 measures that well, they should be able to give your Revels a match, heh heh.

The challenge then is not to get hold of a pair of A4.14. They pop up sometimes and they are still popular so it is easy to sell them IF , and here is the challenge, they are in good condition. It's not a question of if, but when a reforming of the bass drivers needs to be done. Maybe the amp needs a decent service and possibly a re cap. But okay, if you have the time and knowledge to tinker with it, it's not a challenge. Then it's instead a fun hobby project.

 

[Ageve]

The challenge then is not to get hold of a pair of A4.14. They pop up sometimes and they are still popular so it is easy to sell them IF , and here is the challenge, they are in good condition. It's not a question of if, but when a reforming of the bass drivers needs to be done. Maybe the amp needs a decent service and possibly a re cap. But okay, if you have the time and knowledge to tinker with it, it's not a challenge. Then it's instead a fun hobby project.

Yep, the first version of A4.14 is ~40 years old now if I'm not mistaken.

Unfortunately Audio Pro is not what it used to be. T14 is not bad compared to some other inexpensive powered speakers, but I wouldn't call it a Hi-fi speaker.

 

[burmanm]

Awesome, I've waited for a long time for someone to actually measure these. I personally have the T20s at my gym (I payed 50€ for a pair since they have broken BT) and I've been happy with them, since obviously it's not the best acoustic place in any case

Was always wondering what the effect of those treble + bass settings would be to the FR in controlled environment. Hopefully someone measures at some point the newer models also, like the A48s as they have DSP built-in (and if that has any effect on the sound quality). Who knows, maybe the cabin in those is heavier also, as the T14 / T20 are very light indeed (but I think they look nice and the remote is one of the classiest looking ones ever).

 

[amirm]

Nice work. Thanks for posting. Promoted to home page.

 

[Karmacoma]

Got a C3 from that brand, I like it for what it is, good cost/performance ratio.

 

[phoenixdogfan]

Great job, Ageve. If I ever lost everything I had in a fire, or a hurricane, or a tornado, and was waiting for a check from my insurance company so I could once again go shopping for real, I would probably look to pick up a pair of these to tide me over.

 

[Dmitri]

Great review! I love that you added bracing in an attempt to control cabinet resonance and added different damping material to the speaker and remeasured. Adds a bit of extra interest and enjoyment for those of us who like to (in my case, usually to detriment) modify and experiment.
Enjoyed and appreciate the effort you put into this.

BTW. You really look a lot like Weird Al Yankovic. It’s uncanny. ; )

 

[Ageve]

BTW. You really look a lot like Weird Al Yankovic. It’s uncanny. ; )

Haha, yep. It's from this video:

 

[Dmitri]

I saw Weird Al Yankovic in concert years ago as a birthday present for my son. The band was delayed getting there, the concert ran late…and we ended up hitting a deer on the way home at 2am, trashing the front end of our then three week old mini van.

I was a lot more impressed with the band than I thought I would be…played across a number of genre’s and they were really talented. Fun concert and I got to be Uber Father. Win Win!

I was kinda hoping you really were Weird Al, because he owes me a couple of thousand bucks for the cost of the repair to the front of a 2000 Dodge Grand Caravan. I mean seriously. We should’ve been home by midnight. ; )

Pardon my segway from the subject at hand. Just brought back some ”fond memories.“ Again, thanks for the review. Nice work!

 

[Pinkynator]

Audio Pro Addon T14 was sold by one of Sweden's largest department store chains
(...)
Audio Pro was ahead of its time. An active speaker with Ace Bass technology:

Wait a minute... That can't be a coincidence.

 

[MAB]

Wait a minute... That can't be a coincidence.

I saw the sign.

 

[Maiky76]

Here are some measurements of the Audio Pro Addon T14.

I don't know if Audio Pro are sold outside Europe, but it's a Swedish brand founded in 1978. This speaker is powered but not active (passive crossover). It was on sale for ~189 USD/pair (1990 SEK) before being discontinued a few years ago.

View attachment 376693

I measured the right speaker (the one without amplifier).

The measurements are quasi-anechoic (near-field port+woofer measurements corrected for baffle edge diffraction, combined with gated outdoor measurements at 1m distance, 5ms window). Merged at 400 Hz.

Since the speaker has tone controls, I started by measuring the tweeter response with all settings. I ended up using tweeter level 7 (and bass level 7) to get the flattest response.

It turned out to be close to the default setting of 6.

View attachment 376694


Here are the results:

The tweeter behaviour is a bit strange. From 10-12 kHz there's a change in directivity, but above 12 kHz it's almost a flat line. It looks extra weird in the polar maps.

I actually thought something was wrong with the measurements and/or playback of the test signal, so I re-measured the speaker (the whole spin) using 44.1 KHz instead of 96 kHz (to see if it could be caused by the speaker not supporting 24/96 properly (Toslink). The results were identical though, and I ended up using the second spin. That's why it's limited to 20 kHz.



View attachment 376695


View attachment 376696


View attachment 376697


View attachment 376698


The near-field port response is rough, and the woofer response is also a bit jagged. I'm pretty sure it's caused by cabinet resonances. It feels cheaply made and "hollow".

It matches the peak/uneven response in the quasi-anechoic response (800 Hz - 1.6 kHz).


View attachment 376699



Horizontal directivity:

View attachment 376700
View attachment 376706


Vertical directivity:

View attachment 376703
View attachment 376707
View attachment 376708


Distortion:

View attachment 376709


View attachment 376710


View attachment 376711


View attachment 376712


Distortion looks ok at > 150 Hz, even at 90 dB SPL. Below is another story, with 10% distortion at 100 Hz.

I did't measure at higher SPL since the port was already making a lot of noise, and the woofer was moving alot.


My subjective impression is that it has a lot of bass for it's size, and it goes deeper than many other small speakers. The bass distortion is quite high though.

As for the overall sound:

View attachment 376713

No, I'm not comparing it to the Chernobyl disaster. It's not that bad.

The cabinet is audibly resonant though. The bass is impressive for it's size, but a bit muddy. The treble peak causes sharp "s" sounds.

Great effort.
Not sure about the LF directivity: merging a bit cut and shut?
Maybe Vcad might do a better job?

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: 4.1
With Sub: 6.3

Spinorama with no EQ:

• Bump in the 1-2kHz region
• HF way too hot
• Poor directivity

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.

Audio Pro T14 APO EQ LW 96000Hz
June242024-124033

Preamp: -2.10 dB

Filter 1: ON PK Fc 105.6,    -1.23,    2.16
Filter 2: ON PK Fc 765.8,    2.82,    3.70
Filter 3: ON PK Fc 992.7,    -3.66,    1.91
Filter 4: ON PK Fc 1396.3,    -2.31,    7.00
Filter 5: ON PK Fc 2663.1,    -2.26,    4.51
Filter 6: ON PK Fc 3074.6,    2.48,    0.41
Filter 7: ON PK Fc 9976.9,    3.77,    4.21
Filter 8: ON PK Fc 13353.7,    -5.97,    1.65

Audio Pro T14 APO EQ Score 96000Hz
June242024-124033

Preamp: -1.90 dB

Filter 1: ON PK Fc 105.1,    -1.23,    1.60
Filter 2: ON PK Fc 786.2,    2.60,    3.82
Filter 3: ON PK Fc 979.7,    -3.95,    1.91
Filter 4: ON PK Fc 1377.2,    -2.38,    7.00
Filter 5: ON PK Fc 2639.8,    -1.66,    3.51
Filter 6: ON PK Fc 3163.0,    2.94,    0.46
Filter 7: ON PK Fc 5215.3,    -1.51,    1.65
Filter 8: ON PK Fc 13363.7,    -6.85,    2.15

Score EQ LW: 5.7
with sub: 7.9

Score EQ Score: 6.3
with sub: 8.5

Spinorama EQ LW

Spinorama EQ Score

Zoom PIR-LW-ON

Regression - Tonal

Radar no EQ vs EQ score
Nice improvements

 

[kemmler3D]

This EQ would be producing something of a miracle, putting it within striking distance of a lot of KEF offerings with sub... would be interested to hear listening impressions of it.

As for the added bracing - it sure looks like it killed some resonances. Goes to show why all the DIY folk are so hot on them.

 

[Thomas_A]

Audio Pro is not what it was. The first A4-14 and 2-25 models in 1979 were good. Would be interesting to see one of them measured. I unfortunately away my first speaker which was the Audio Pro 2-25.

 

[YSC]

Here are some measurements of the Audio Pro Addon T14.

I don't know if Audio Pro are sold outside Europe, but it's a Swedish brand founded in 1978. This speaker is powered but not active (passive crossover). It was on sale for ~189 USD/pair (1990 SEK) before being discontinued a few years ago.

View attachment 376693

I measured the right speaker (the one without amplifier).

The measurements are quasi-anechoic (near-field port+woofer measurements corrected for baffle edge diffraction, combined with gated outdoor measurements at 1m distance, 5ms window). Merged at 400 Hz.

Since the speaker has tone controls, I started by measuring the tweeter response with all settings. I ended up using tweeter level 7 (and bass level 7) to get the flattest response.

It turned out to be close to the default setting of 6.

View attachment 376694


Here are the results:

The tweeter behaviour is a bit strange. From 10-12 kHz there's a change in directivity, but above 12 kHz it's almost a flat line. It looks extra weird in the polar maps.

I actually thought something was wrong with the measurements and/or playback of the test signal, so I re-measured the speaker (the whole spin) using 44.1 KHz instead of 96 kHz (to see if it could be caused by the speaker not supporting 24/96 properly (Toslink). The results were identical though, and I ended up using the second spin. That's why it's limited to 20 kHz.



View attachment 376695


View attachment 376696


View attachment 376697


View attachment 376698


The near-field port response is rough, and the woofer response is also a bit jagged. I'm pretty sure it's caused by cabinet resonances. It feels cheaply made and "hollow".

It matches the peak/uneven response in the quasi-anechoic response (800 Hz - 1.6 kHz).


View attachment 376699



Horizontal directivity:

View attachment 376700
View attachment 376706


Vertical directivity:

View attachment 376703
View attachment 376707
View attachment 376708


Distortion:

View attachment 376709


View attachment 376710


View attachment 376711


View attachment 376712


Distortion looks ok at > 150 Hz, even at 90 dB SPL. Below is another story, with 10% distortion at 100 Hz.

I did't measure at higher SPL since the port was already making a lot of noise, and the woofer was moving alot.


My subjective impression is that it has a lot of bass for it's size, and it goes deeper than many other small speakers. The bass distortion is quite high though.

As for the overall sound:

View attachment 376713

No, I'm not comparing it to the Chernobyl disaster. It's not that bad.

The cabinet is audibly resonant though. The bass is impressive for it's size, but a bit muddy. The treble peak causes sharp "s" sounds.

Looks quite a rough response >1khz, likely some kind of resonance? The peak above 10khz is kind of weird also, overall shape reminds me of some focal speakers, maybe that’s what they are aiming at

 

[MAB]

Haha, yep. It's from this video:

It's a magnificent song and video, from a genuine talent.

Thanks for the review too.

 

[Ageve]

Great effort.

Not sure about the LF directivity: merging a bit cut and shut?

Maybe Vcad might do a better job?

...

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.

Thanks!

I'm not sure. I tried 1/2 and 1 octave blending BW at 400-500Hz in VituixCAD (ended up using 400Hz and 1/2 octave).


The txt-files wouldn't load correctly in APO/Peace (version 1.6.6.0) for some reason, but it worked after modifying them:

Audio Pro T14 APO EQ LW 96000Hz
June242024-124033

Preamp: -2.10 dB

Filter 1: ON PK Fc 105.6 Hz Gain -1.23 dB Q 2.16
Filter 2: ON PK Fc 765.8 Hz Gain 2.82 dB Q 3.70
Filter 3: ON PK Fc 992.7 Hz Gain -3.66 dB Q 1.91
Filter 4: ON PK Fc 1396.3 Hz Gain -2.31 dB Q 7.00
Filter 5: ON PK Fc 2663.1 Hz Gain -2.26 dB Q 4.51
Filter 6: ON PK Fc 3074.6 Hz Gain 2.48 dB Q 0.41
Filter 7: ON PK Fc 9976.9 Hz Gain 3.77 dB Q 4.21
Filter 8: ON PK Fc 13353.7 Hz Gain -5.97 dB Q 1.65

and

Audio Pro T14 APO EQ Score 96000Hz
June242024-124033

Preamp: -1.90 dB

Filter 1: ON PK Fc 105.1 Hz Gain -1.23 dB Q 1.60
Filter 2: ON PK Fc 786.2 Hz Gain 2.60 dB Q 3.82
Filter 3: ON PK Fc 979.7 Hz Gain -3.95 dB Q 1.91
Filter 4: ON PK Fc 1377.2 Hz Gain -2.38 dB Q 7.00
Filter 5: ON PK Fc 2639.8 Hz Gain -1.66 dB Q 3.51
Filter 6: ON PK Fc 3163.0 Hz Gain 2.94 dB Q 0.46
Filter 7: ON PK Fc 5215.3 Hz Gain -1.51 dB Q 1.65
Filter 8: ON PK Fc 13363.7 Hz Gain -6.85 dB Q 2.15

I've been listening for a while, switching between them, at ~3m distance. It's a big improvement. Most of the "boxiness" is gone, and the treble sizzle.

The flat LW EQ seems to work for near-field listening as well.

The cabinet is still playing along with the music though (It would probably look bad in a CSD plot), and as soon as there's a louder female voice or electric guitar, the squeaky/resonant sound returns. Maybe high IMD?

Here's a new measurement in my living room, using the LW EQ (port and woofer remeasured as well).

+/- 1.82 dB, 58 Hz - 20 kHz

 

[Maiky76]

The txt-files wouldn't load correctly in APO/Peace (version 1.6.6.0) for some reason, but it worked after modifying them:

Thanks for that! Good catch.
I made some trial modifications to my script and forgot to revert them...
I am using a Mac so I can't actually test the configs directly.
Would you mind to try these to confirm they are OK?