DIY 2-way with complete spinorama / CTA2034A measurements - Purifi and Scan-Speak


  • Active + Aluminium cone (PTT6.5X-04-NAA)

  • Active + Fibre cone (PTT6.5X-04-NFC)

  • Passive + Aluminium cone

  • Passive & Fibre cone

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If I have not missed anything, there is one picture in post 1, with dimensions of the enclosure and anechoic extension frequencies.
And another picture in post 40.
And you apparently like how it sounds, so it must be functional.

Perhaps some pictures at the back (passive radiator) ?
Frequency measurements, crossover design, ..., etc ?
Looks like quite a different design than the SPK8 ?

Thanks in advance,
Hi Patrick,

Unfortunately I haven’t had the chance to take full measurements of it. At the moment in Northern Australia it 90 degrees Fahrenheit almost every day, with chance of storm or heavy rain. So I'm going to take measurements in 1 or 2 sessions on a fine day, after all the cabinets were completed.

Here is a photo of rear of the smallest prototype, next to an standard sized iPhone (non-Max, non Plus) case.


If one were to build a plate amp version (TBD) on the back panel, the passive radiators can be moved to side panel, adjacent to the tweeter with little impact on the bass response. Aesthetically I much prefer hidden passive radiators/ports.

I got sidetracked one evening and wired it up to play without the tweeter, or even a crossover. And it sounded very impressive.

So I measured it- here's the PTT4.0X-04 in this cabinet, measured with a gate of 6ms.

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I already have the old passive radiators and have lots of experience tuning it.

As you can see from the frequency response measurement it is VERY well behaved, without a crossover, or even baffle step compensation. It misses the top two octaves (4-16KHz) that a tweeter provides, but is very listenable as is.
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Yes the walls are deep enough for dual opposed passive radiators on the side panels. This frees up space for the active electronics or passive crossover on the back panels.

In terms of industrial design, it is better to have passive radiators with inverted surrounds such that the driver can be flush with the cabinet.
Lots of queries about the tiny speaker.
Here's the frequency response + harmonics + noise floor. NB. The dip at 60Hz is the from the room.

Cabinet is 3.5L internal.
f3 51 Hz
f6 47 Hz
f10 412 Hz

Twin SB13PFCR passive radiators may be rear mounted (-> invisible) or side mounted (-> force cancellation)



As you can see, this speaker is one for Spinal Tap- these go to 11:
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Very interesting that almost no one has asked me what ultra low distortion sounds like. But they all want to hear it for him/herself.

I guess there’s no point asking what chocolate taste like. OR if you are deaf, asking what sound is like.

Language is just the intermediary.

The black box (brain) just want to experience it (input) and make the neuronal connections (learn) for itself.
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A good point @tktran303 !
Like @HiFiCompass once mentioned , once ceramic going back to paper is not easy or something along those lines.
For me transparency in the sound and soundstage. The very short answer, and after quite some pondering and discussing with my wife (she too knows the difference) decided to replace the drivers in my current speakers with purifi's. Still to arrive and will take some time, but given the info about these drivers will be better in the bass range for sure, and expect also a step up in the midrange. Like you said about chocolate ;-) or taste of some good coffee ;-) .
Update: PTT 6.5X04-NFA Fibre cone, Active version completed for miniDSP 2x4HD and Flex 8.

Includes DSP selectable settings for near wall placement, treble tilt +/-2dB, and flat on axis response VS flat power response.

Coming- DSP selectable settings for on-table desktop place for Danish Duo Micro.
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