Converting an Adam Audio T5V to sealed?

[ppataki]

Quick and interesting update in the meantime:
After performing all the measurements I was doing a real-time A/B listening test with the treated closed speaker vs the non-treated closed speaker (left and right respectively)

I can hear the treble being muffled for the treated one vs the untreated one which I find very strange. It was totally not visible on the FR curve if you check above...

Later today I will try to do a root-cause analysis:
- first remove the foam filling only and re-do the AB testing
- then I plan to remove the vibrodamping sheets from/around the tweeter and do the AB testing again
- lastly I might re-open the port and do an AB again to see if the cabinet being sealed/ported has any impact on the highs (again would find it very strange since the tweeter is closed-back)

Will report my findings

 

[AnalogSteph]

Weird. Can you reproduce this when swapping the speakers between positions? If the muffled treble stays with the treated speaker, measure it again. Maybe a tweeter connection has become dislodged or something in the meantime. I don't believe in ghosts.

 

[ppataki]

Weird. Can you reproduce this when swapping the speakers between positions? If the muffled treble stays with the treated speaker, measure it again. Maybe a tweeter connection has become dislodged or something in the meantime. I don't believe in ghosts.

Yes indeed, there was no ghost
The root cause is unfortunately more prosaic
I have had many troubles with my left ear (multiple eardrum perforations, surgeries, etc.) and I have just figured it out during this experiment that I cannot hear so much treble detail with my left ear compared to my right ear...

I have placed the speakers in a different place, still heard the difference, then I swapped them (left-right) and still heard the difference from the same side (left) and when I listened to it with my right ear the treble was fine - that's how I realized that the issues is not with the treated speaker but with my ear

I am including two videos here about the two speakers, the first video is the left which is the treated-and-closed one and the second video is the right which is the original unaltered reflex cabinet:

New video by Peter Pataki

photos.app.goo.gl

New video by Peter Pataki

photos.app.goo.gl

The next step (probably this weekend) is that I will remove all the electronics from the cabinets and will drive the speakers with a pair of Sabaj A30A amps and will set up the crossover on my PC - I will post the measurements accordingly

 

[Brazy]

If you are afraid of nasty odors getting into your bass ports. Would it it help to plug the ports with a thin sheet of active carbonated filter? Would it work to not fully plug the port?

 

[terryforsythe]

If you are afraid of nasty odors getting into your bass ports. Would it it help to plug the ports with a thin sheet of active carbonated filter? Would it work to not fully plug the port?

Probably not. Any additional restriction of air flow will change the tuning of the port. How much it changes the tuning depends on how restrictive the filter is to air flow.

 

[ppataki]

Let's see some pictures and the measurements now when converted to fully active!

I have removed the internal electronics and driving the speakers with two pairs of Sabaj A30A FDAs
Crossover is done with Jriver, this time using classic minimum phase low pass and high pass filters
Instead of using the original 3000Hz crossover point I figured (based on the measurements) that using 3500Hz with 24dB/octave is a better choice
I also synchronized the tweeter with the woofer (setting appropriate delay)

The cabinet is completely sealed (I also tested to make sure it is airtight)


Frequency response original reflex vs fully active sealed:

There was a high-pass filter used in the original
The difference above 10kHz is due to the fact that I could not measure the speaker in the exact same location, there can be 1-2cm difference

Phase:

There is less phase rotation in the treble

Step response looks very different due to the time alignment of the drivers:

Distortion is naturally much higher with the sealed design - one would definitely need a sub when used this way

IR is way cleaner with the sealed design:

GD is lower, except for that nasty spike at 65Hz (room??)
Since the sub is integrated from 80Hz, I guess it would not matter much either way

The biggest difference is in the Wavelet diagram, clearly showing way less post-ringing and peak energy delay with the sealed design

Sealed:

Reflex:

You can see the mdat file attached for your scrutiny

Some thoughts:
- I liked the sound of the original version too, IMHO these are a hell of a price/value champion speakers, I honestly cannot think of anything coming close to this quality at this price point
- I was annoyed by the hiss of the original version though - one shall consider that for near-field usage. It bothered me even at a distance of 250cm. Of course with the fully active mod this issue was gone
- How can I describe the sound after all these modifications? Subjectively speaking: 'faster' mids and lows. More apparent dynamic range. More effortless presentation. Sound stage became more precise
- Talking about the sound stage: this is the one thing that I find difficult to get used to after having built more than a dozen of full range driver projects. To my personal taste I find the holographic projection of full range speakers unmatched. I have listened to many multiway speakers in my life (visited the Munich High-End Show 5 times) but no speakers could come close to literally any full range driver in this regard. Again, this is totally subjective! (and I know that full range drivers have many shortcomings at the same time)
- I am now in the process of integrating the T5Vs with both of my subs in the living room, I will post measurements about that in this post
- the T5Vs will probably not stay for long, but it was a fun project and I have learned a lot about woofer/tweeter integration, reflex vs sealed, fully active multiway design, etc.
- my next project will be a DIY 5" coax (two-way) design - this is the area I want to venture into as the next item on my bucket list (I wonder if their projection will come close to that of full range drivers....)

I hope this was useful to a lot of folks here - any comments or questions please don't hesitate

 

[terryforsythe]

Nicely done!!!

I also removed the passive crossovers from my Elac UniFi Reference speakers and went all active. I also added additional bracing and damping material, in addition to plugging the ports. On those speakers, the modifications made a significant improvement

Talking about the sound stage: this is the one thing that I find difficult to get used to after having built more than a dozen of full range driver projects. To my personal taste I find the holographic projection of full range speakers unmatched.

That makes sense - no spacing between drivers and no crossover.

my next project will be a DIY 5" coax (two-way) design

That sounds like a fun project. My current speakers, Elacs noted above and KEF LS60s, both of which use concentric drivers, soundstage and image very well.

Have you chosen your 5" coax driver? I have looked for off-the-shelf concentric drivers to build my next DIY speakers, but have not found any with measurements I really like. All of the smaller concentric drivers where I have seen the data have high THD above the frequency where I would cross them over to a subwoofer. Adding a mid-woofer would alleviate that, though.

Also, all off-the-shelf concentric drivers where I have seen the data have diffraction issues, as do my Elacs, but not so much with my KEFs. The more severe diffraction I usually see is up around 7kHz-10kHz due to the tweeter signal diffracting at the gap/structure between the tweeter and woofer. Sometimes diffraction also shows up due to the tweeter signal diffracting off of the woofer surround/frame, maybe in the 2kHz-3kHz range for a 5" driver. Both tend to get better 10-20 degrees off-axis, however.

KEF seems to do the best job with concentric drivers, especially in their reference series where the THD is very low in their operational frequency range and the diffraction is negligible. But, I don't know whether it is possible to buy just those drivers without having to buy the speakers.

 

[ppataki]

Nicely done!!!

Thank you

Have you chosen your 5" coax driver?

Yes, in fact I just ordered them 5 minutes ago
They are these ones: Sica 5,5 C 1,5 PL
I made my decision based on this and this.

I paid 194 EUR for the pair - I think for that amount they are a price/value champion

I am going to create a dedicated thread for the project once they arrive (by early January I hope)

 

[terryforsythe]

Yes, in fact I just ordered them 5 minutes ago
They are these ones: Sica 5,5 C 1,5 PL
I made my decision based on this and this.

Nice. I had not seen those drivers before.

I can't wait to see how those speakers turn out.