Phase Tech PC 3.1 Speaker Measurements

[amirm]

These are the measurements of a used/vintage Phase Tech PC 3.1 center speaker. I believe it originally cost US $600. I was kindly sent to me by a member:

As you can see, the sample is a crusty one! I must say, I had not seen foam over woofers before. You can rotate the midrange/tweeter assembly as to use the speaker vertically.

Owner told me that this was one of the companies paying attention to directivity as being an important thing. Seeing how it has a mid-range, gives me hope that it delivers on that.

These write-up is rather brief because I am not sure if I have a working sample. I cannot find any measurements of this unit. There is some for the version 2 which looks better.

Phase Tech PC 3.1 Speaker Measurements
Our anechoic frequency response shows clear problem where the mid-range is supposed to be delivering:

From memory, the midrange is crossed from 700 Hz. That would in theory fill that hole but maybe they wanted this kind of V shaped response. Besides that, we have a few wide resonances. Directivity is not great causing early window and predicted in-room responses leaving something to be desired:

As noted, the mid-range should be solving the beaming issue with dual drivers but it clearly is not:

Vertically of course doesn't have that problem:

I was surprised and dismayed that I could clearly hear distortion at 94 dBSPL:

This is topped by very low impedance:

Finally, waterfall shows resonances as we would expect:

Conclusions
It should be obvious that this is either a broken speaker or broken by design. I can't be sure which is which. Could have discarded the measurements but after all the work that went into it (including confirming that the midrange was working), I thought I post it anyway.

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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/

 

[Maiky76]

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: 3.0
With Sub: 4.9

Spinorama with no EQ:

• not linear at all
• some directivity errors
• SOme do it much better

Directivity:

Better stay at tweeter height
Horizontally, on axis.

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.
• With some SPK/amp combo, the boosts and preamp gain (loss of Dynamic range) need to be carefully considered to avoid issues with, amongst other things, too low a Max SPL or damaging your device. You have beed warned.

Score EQ LW: 5.9
with sub: 7.6

Score EQ Score: 6.5
with sub: 8.3

Phase Technology PC 3.1 APO EQ LW 96000Hz
March202025-142326

Preamp: -5.00 dB

Filter 1: ON HPQ Fc 43.3 Hz Gain 0.00 dB Q 1.89
Filter 2: ON PK Fc 132.8 Hz Gain -3.38 dB Q 0.78
Filter 3: ON PK Fc 482.3 Hz Gain -1.02 dB Q 1.25
Filter 4: ON PK Fc 1160.2 Hz Gain 5.32 dB Q 0.98
Filter 5: ON PK Fc 2359.2 Hz Gain -3.97 dB Q 2.13
Filter 6: ON PK Fc 2790.0 Hz Gain 3.25 dB Q 1.67
Filter 7: ON PK Fc 4415.7 Hz Gain -3.31 dB Q 2.10
Filter 8: ON PK Fc 9745.6 Hz Gain 2.94 dB Q 2.80
Filter 9: ON PK Fc 11001.6 Hz Gain -6.40 dB Q 3.76

Phase Technology PC 3.1 APO EQ Score 96000Hz
March202025-142326

Preamp: -5.10 dB

Filter 1: ON HPQ Fc 43.3 Hz Gain 0.00 dB Q 1.89
Filter 2: ON PK Fc 130.8 Hz Gain -3.38 dB Q 0.90
Filter 3: ON PK Fc 488.0 Hz Gain -1.37 dB Q 1.87
Filter 4: ON PK Fc 1209.5 Hz Gain 6.00 dB Q 0.93
Filter 5: ON PK Fc 1772.6 Hz Gain -2.34 dB Q 2.09
Filter 6: ON PK Fc 2423.9 Hz Gain -3.32 dB Q 2.24
Filter 7: ON PK Fc 2997.2 Hz Gain 3.59 dB Q 2.06
Filter 8: ON PK Fc 4391.2 Hz Gain -3.53 dB Q 1.47
Filter 9: ON PK Fc 9243.8 Hz Gain 2.03 dB Q 3.70
Filter 10: ON PK Fc 10972.5 Hz Gain -5.98 dB Q 2.69

Spinorama EQ LW

Spinorama EQ Score

Zoom PIR-LW-ON

Regression - Tonal

Radar no EQ vs EQ score
Large improvements?

The rest of the plots is attached.

 

[alex-z]

Using a 1.5" mid with a 1" tweeter is honestly a bit weird. A 2" mid + .75" tweeter could achieve a lower woofer crossover point and better high frequency extension.

The foam in the woofers I believe is intended to mitigate high order distortion products. It does technically work but is a bit pointless when the rest of the speaker is a distortion/resonance factory.

 

[amirm]

Using a 1.5" mid with a 1" tweeter is honestly a bit weird.

That was my thought as well as I was typing the review. Likely they crossed the midrange too high due to it being so small.

 

[phoenixdogfan]

The FR on them looks like a lot of people's mattresses if they keep them for longer than ten years.

Thanks for the nice review, Amir.

 

[MZKM]

Preference Rating
SCORE: 3.0
SCORE w/sub: 4.9

Sensitivity: 87.3dB (300Hz-3kHz)
Frequency response: ±8.0dB 80Hz-20kHz

​

 

[thewas]

I personally didn't even know that brand as it was possibly not offered in Europe so I wonder how popular it was in the US, it seems to be from early 00s https://www.soundandvision.com/content/phase-technology-premier-collection-surround-speaker-system

 

[crappypanther]

throw it away

 

[Multicore]

It should be obvious that this is either a broken speaker or broken by design. I can't be sure which is which. Could have discarded the measurements but after all the work that went into it (including confirming that the midrange was working), I thought I post it anyway.

What motivated you to measure the speaker, Amir?

 

[Cogito]

This is surprising to me how badly these performed. I had their PC80/90 Sub/Sat system (Bought some 30+ years ago) and as I recall, were a wonderful performer.

 

[renaudrenaud]

This is surprising to me how badly these performed. I had their PC80/90 Sub/Sat system (Bought some 30+ years ago) and as I recall, were a wonderful performer.
View attachment 437679

Life was more beautiful 30 years ago. We were young, believing in cables, tubes, high end brands. Amir destroyed our dreams and now we buy Fosi equipment.

 

[robh]

I remember those. I almost bought them because my local "Hi-Fi" dealer sold them.

 

[Mikig]

Life was more beautiful 30 years ago. We were young, believing in cables, tubes, high end brands. Amir destroyed our dreams and now we buy Fosi equipment.

Yes, but mostly because we were 30 years younger!

 

[Mikig]

Avrei potuto scartare le misurazioni, ma dopo tutto il lavoro che ci è stato fatto (incluso il confermare che la fascia media stava funzionando), ho pensato di pubblicarlo comunque.

You did well to keep the work and publish it. Add a piece to the knowledge of this world, Even if the "happy panther" does not appear. Thanks Amirm for the test, always interesting.

 

[Cogito]

BTW For those who don't know, Phase Technology invented the Soft Dome tweeter (Or at least were the 1st to patent it).

 

[Mart68]

Does the very low impedance dips suggest the speaker might not be working properly?

Why design a centre speaker that tortures AVRs?

 

[AnalogSteph]

Likely they crossed the midrange too high due to it being so small.

And, going by the distortion graphs, the midrange still is decidedly unhappy. It would have needed a substantially larger waveguide at the very least.

The foam in the woofers I believe is intended to mitigate high order distortion products.

Should help address breakup modes as well. It's basically an additional 1st-order lowpass.

 

[jkasch]

BTW For those who don't know, Phase Technology invented the Soft Dome tweeter (Or at least were the 1st to patent it).

IIRC, Bill Hecht the founder of Phase Tech is credited with the invention of the soft dome tweeter. Was patented in ‘67.

 

[Cogito]

IIRC, Bill Hecht the founder of Phase Tech is credited with the invention of the soft dome tweeter. Was patented in ‘67.

I guess he was tired of the hard dome tweeters getting pushed in bu people in the showroom, so he did a mockup of the tweeter using fabric. To his amazement, it sounded great and here we are now!

 

[AndreaT]

The midrange in a center speaker should be flawless as it is often part of a home theater setup, and Dolby 5.1 directs most of the dialogue to the center speaker. A very bad choice for improving intelligibility of actors’ voices.