See posting #9.
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Converting an Adam Audio T5V to sealed?
- Thread starter ppataki
- Start date
dasdoing
Major Contributor
some box resonances might still be coming out of it after high passed, but really? probably impossible to hear even in the nearfield
dasdoing
Major Contributor
lol. what speaker is that?
terryforsythe
Major Contributor
Yes. Try it both ways and see what works best in your system. Plugging the port will reduce the group delay at the low end of the speakers range, and significantly reduce, if not eliminate, noise/resonances coming out of the port.
In my system, plugging my speaker ports helped me get a smoother frequency response when using a subwoofer. I have front firing ports. I plugged them with dense foam.
On the other hand, another member I was communicating with here in the forum some time back stated that plugging the ports on his speakers made his frequency response worse. He indicated he got a better transition to the subwoofer with the ports left open.
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- Jul 23, 2019
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Is the above example of a port resonance what is referred to as "a worst case scenario"?
- Joined
- Jul 23, 2019
- Messages
- 519
- Likes
- 546
@terryforsythe Did you apply a high-pass filter to the main speakers? If so, what were the settings?
The results depend a lot on the magnitude and phase response of the subwoofer and main speaker systems, as well as the type of low-pass and high-pass filtering that's been applied.
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dasdoing
Major Contributor
Is the above example of a port resonance what is referred to as "a worst case scenario"?
It's so loud it is probably some part vibrating inside. could be just something loose
terryforsythe
Major Contributor
Yes. There are more settings I experimented with than I can remember or list. From what I do remember, with the ports open I experimented with crossover frequencies from 60Hz - 120Hz. With the ports plugged I experimented with crossover frequencies from 80Hz-120Hz. For each frequency I experimented with, I time aligned the woofers and subwoofer at the listening position. I also experimented with deviating the time delays from that setting to measure the impact on frequency response. I ended up using 8th order LR crossovers with the ports plugged and the woofers/subwoofer time aligned to be in phase at the crossover frequency, as measured at the listening position.
Agreed.
- Thread Starter
- #31
Just a small update: since it is Cyberweek at Thomann, I have decided to order the T5Vs now, I will get them next week
There is a 30-day right of withdrawal with Thomann so I will have a month to play with the speakers
Either next week or the week after I shall start sharing the measurements here, stay tuned!
There is a 30-day right of withdrawal with Thomann so I will have a month to play with the speakers
Either next week or the week after I shall start sharing the measurements here, stay tuned!
- Thread Starter
- #32
I received my T5Vs on Wednesday and yesterday I performed all the measurements
I will start with the objective measurements and then I will share my subjective impressions as well and then the next steps planned
Frequency response of the default state (reflex) vs. closed (port stuffed with melamine foam and sealed with vibrodamping sheets)
As anticipated the bass response start to decrease from around 200Hz. I suspect that physically removing the port will futher increase this effect.
Now let's see the phase:
What I find strange is the change of phase in the high frequencies, the reflex design deviates towards +360 degrees whereas the closed design deviates towards -360 degrees
I thought that plugging the port will only have an impact on the lows but not the highs.... any comments would be welcome here
When it comes to further temporal curves, it is worth checking the Wavelet diagrams
Reflex:
Closed:
The post-ringing of the reflex design is totally visible - as expected
Let's see the same after I have applied a linear phase low shelf filter combined with a linear phase high pass at 40Hz:
No real impact on the post-ringing (nor on the GD)
I have also performed some FSAF measurements (the latest invention in REW) to see the TD+N curves
Interestingly the distortion in the highs seems to get elevated as well in the closed design..... again I would appreciate some comments please
Can that be due to increased cabinet resonance?
Just for fun, some measurements after sub integration and Dirac:
I like the Wavelet curve:
And it is great to see how Dirac fixes the step response curve (to eliminate the time of arrival difference between the tweeter and the midwoofer)
And it fixed the phase response in the highs too:
I am attaching the mdat file too for your scrutiny
Now let me share my subjective impressions (note: these are all subjective/empirical experiences and I have no means to support them with any additional measurements)
When I first listened to the T5Vs (just putting them in the room as you can see in the above picture exactly where my full range MAOP spheres generally are) I was not very impressed.
I mean these speakers sound waaaaay better than their price tags would make you think but compared to my (fully DSP-d) spheres they sounded rather lifeless and boring
I was expecting that the dedicated ribbon tweeter would make a huge difference along with the almost perfect directitivity of these speakers compared to the full range spheres that do a really crappy job in that department.... but they did not, really
The biggest difference is how the stage is presented; let me try to make a drawing about what I hear
The drawing in the top is how I hear the soundstage with the full range drivers (and not just with the MAOPs but with all the nearly dozen different full range drivers that I have tried in the last 5 years)
The drawing in the bottom shows what I hear with the T5Vs
Probably the second one is the 'normal' and 'correct' way but subjectively I prefer the first
Then I continued my experiment and integrated my 15" sealed DOS sub (crossed at 80Hz, 24dB/octave, linear phase) and applied Dirac
Then I said: Now we are talking!
The tweeter came to life (with some additional post-Dirac filters) and I started to hear nuances in the highs that I was not able to hear with the full range drivers before
The stage still is different but I guess that is inherent but I am happy to stand corrected
Generally speaking, listening to these speakers after all the DSP is definitely a pleasant experience and I would very strongly recommend it to anybody (reflex or closed, according to your taste)
About that topic: I totally prefer the way it sounds when closed, I know there is no such thing as a 'fast' speaker but that is what I hear, it sounds 'faster' and the transients got a whole lot better + I no longer hear the sound of the port (I guess that is the air velocity)
I have decided to keep them and continue the journey of experimentation with them:
- next week I will improve the damping and the bracing of the cabinets since they are pretty lively - I want them to become more inert. I believe that shall have an impact on midrange clarity and sound stage too (again, happy to stand corrected). I will post pictures and measurements before/after. I will appy vibrodamping sheets, felt, melamine foam and the so-called wire strainers for bracing (that I used in my last sub project with great success)
- in December on in January (or whenever I will have the time) I will actually remove the whole amp board and all electronics from the cabinets and will drive the speakers with a pair of Sabaj A30A amps and apply crossover with my PC based DSP in Jriver using linear phase technology. Will post measurements before/after too.
That will be a really exciting next step
That's all for now, any comments/questions are welcome
I will start with the objective measurements and then I will share my subjective impressions as well and then the next steps planned
Frequency response of the default state (reflex) vs. closed (port stuffed with melamine foam and sealed with vibrodamping sheets)
As anticipated the bass response start to decrease from around 200Hz. I suspect that physically removing the port will futher increase this effect.
Now let's see the phase:
What I find strange is the change of phase in the high frequencies, the reflex design deviates towards +360 degrees whereas the closed design deviates towards -360 degrees
I thought that plugging the port will only have an impact on the lows but not the highs.... any comments would be welcome here
When it comes to further temporal curves, it is worth checking the Wavelet diagrams
Reflex:
Closed:
The post-ringing of the reflex design is totally visible - as expected
Let's see the same after I have applied a linear phase low shelf filter combined with a linear phase high pass at 40Hz:
No real impact on the post-ringing (nor on the GD)
I have also performed some FSAF measurements (the latest invention in REW) to see the TD+N curves
Interestingly the distortion in the highs seems to get elevated as well in the closed design..... again I would appreciate some comments please
Can that be due to increased cabinet resonance?
Just for fun, some measurements after sub integration and Dirac:
I like the Wavelet curve:
And it is great to see how Dirac fixes the step response curve (to eliminate the time of arrival difference between the tweeter and the midwoofer)
And it fixed the phase response in the highs too:
I am attaching the mdat file too for your scrutiny
Now let me share my subjective impressions (note: these are all subjective/empirical experiences and I have no means to support them with any additional measurements)
When I first listened to the T5Vs (just putting them in the room as you can see in the above picture exactly where my full range MAOP spheres generally are) I was not very impressed.
I mean these speakers sound waaaaay better than their price tags would make you think but compared to my (fully DSP-d) spheres they sounded rather lifeless and boring
I was expecting that the dedicated ribbon tweeter would make a huge difference along with the almost perfect directitivity of these speakers compared to the full range spheres that do a really crappy job in that department.... but they did not, really
The biggest difference is how the stage is presented; let me try to make a drawing about what I hear
The drawing in the top is how I hear the soundstage with the full range drivers (and not just with the MAOPs but with all the nearly dozen different full range drivers that I have tried in the last 5 years)
The drawing in the bottom shows what I hear with the T5Vs
Probably the second one is the 'normal' and 'correct' way but subjectively I prefer the first
Then I continued my experiment and integrated my 15" sealed DOS sub (crossed at 80Hz, 24dB/octave, linear phase) and applied Dirac
Then I said: Now we are talking!
The tweeter came to life (with some additional post-Dirac filters) and I started to hear nuances in the highs that I was not able to hear with the full range drivers before
The stage still is different but I guess that is inherent but I am happy to stand corrected
Generally speaking, listening to these speakers after all the DSP is definitely a pleasant experience and I would very strongly recommend it to anybody (reflex or closed, according to your taste)
About that topic: I totally prefer the way it sounds when closed, I know there is no such thing as a 'fast' speaker but that is what I hear, it sounds 'faster' and the transients got a whole lot better + I no longer hear the sound of the port (I guess that is the air velocity)
I have decided to keep them and continue the journey of experimentation with them:
- next week I will improve the damping and the bracing of the cabinets since they are pretty lively - I want them to become more inert. I believe that shall have an impact on midrange clarity and sound stage too (again, happy to stand corrected). I will post pictures and measurements before/after. I will appy vibrodamping sheets, felt, melamine foam and the so-called wire strainers for bracing (that I used in my last sub project with great success)
- in December on in January (or whenever I will have the time) I will actually remove the whole amp board and all electronics from the cabinets and will drive the speakers with a pair of Sabaj A30A amps and apply crossover with my PC based DSP in Jriver using linear phase technology. Will post measurements before/after too.
That will be a really exciting next step
That's all for now, any comments/questions are welcome
Attachments
Last edited:
AnalogSteph
Major Contributor
Looks like a slight difference in detected t=0 (reflex seems more accurate), resulting in a time offset between the measurements. You should be able to correct that manually.
terryforsythe
Major Contributor
I have not seen that before, but I wasn't paying attention to the tweeter group delay when tuning my woofer/subwoofer transition. The TD+N curves may provide a clue. It seems like the tweeter is being affected by the port. I wonder whether the back of the tweeter is open to the inside of the cabinet rather than having a sealed back. That might explain what is happening.
On another note, here is a video that came out yesterday, which includes discussion of the topic of a sealed vs. vented speaker enclosure when using subwoofers.
- Thread Starter
- #35
I will confirm that tonight (will share pictures too)
But how could that be? I mean technically.
I was under the impression that cabinet type has no impact on the tweeter
terryforsythe
Major Contributor
Generally speaking, what is happening inside the cabinet should not affect a closed back tweeter. Resonances of the baffle may impact it, though, but what is shown in your charts does not look like a resonance to me.
Typically, open back tweeters are used in open baffle designs, and vented tweeters usually have their own sub-enclosure which should do a pretty good job isolating the tweeter from what is going on in the cabinet. It would seem strange to me if your tweeters are open back or vented into the enclosure. But, I don't know what else would cause the TH+N and phase changes you measured by merely plugging the port. Perhaps it could be measurement errors? You could try measuring it again with the port plugged and unplugged to see if you get the same results.
- Thread Starter
- #37
Today afternoon I started enhancing the boxes from an acoustic perspective (damping and bracing)
I have run out of vibrodamping sheets so today I could only finish one of the cabinets, I will probably finish the other on Wednesday
Let's see the pictures before:
Tweeter seems to be totally closed @terryforsythe so I guess it must have been a measurement anomaly as stated by @AnalogSteph
Now let's see the process
First I removed the polyfill - that revealed some additional bracings
Then I applied the 4mm thick vibrodamping sheets
Reflex tube fully removed
10mm thick felt applied with some additional bracing
And finally the melamine foam with the port closed
Let's see a knock test video:
photos.app.goo.gl
Not sure how much can be heard through the video but the difference is day and night
I will post some before/after measurements in my next post, stay tuned!
I have run out of vibrodamping sheets so today I could only finish one of the cabinets, I will probably finish the other on Wednesday
Let's see the pictures before:
Tweeter seems to be totally closed @terryforsythe so I guess it must have been a measurement anomaly as stated by @AnalogSteph
Now let's see the process
First I removed the polyfill - that revealed some additional bracings
Then I applied the 4mm thick vibrodamping sheets
Reflex tube fully removed
10mm thick felt applied with some additional bracing
And finally the melamine foam with the port closed
Let's see a knock test video:
New video by Peter Pataki
photos.app.goo.gl
Not sure how much can be heard through the video but the difference is day and night
I will post some before/after measurements in my next post, stay tuned!
Last edited:
- Thread Starter
- #38
Now let's see the measurements before/after the acoustic treatment!
FR: not much change
Phase: 360° less rotation in the lows with the treated one
Distortion: ignoring the <30Hz range there are no huge differences (maybe that peak around 5kHz that disappeared)
The T60M curve looks significantly better with the treated one:
Very interesting is the Wavelet curve but this time not so much in the lows but in the 20kHz-1kHz range:
Non-treated:
Treated: this one looks cleaner to me
Please see the mdat attached (only with the before/after treatment measurements)
Subjectively I cannot say anything yet, since only one of the speakers are done
On Wednesday hopefully I will be able to comment more on that
FR: not much change
Phase: 360° less rotation in the lows with the treated one
Distortion: ignoring the <30Hz range there are no huge differences (maybe that peak around 5kHz that disappeared)
The T60M curve looks significantly better with the treated one:
Very interesting is the Wavelet curve but this time not so much in the lows but in the 20kHz-1kHz range:
Non-treated:
Treated: this one looks cleaner to me
Please see the mdat attached (only with the before/after treatment measurements)
Subjectively I cannot say anything yet, since only one of the speakers are done
On Wednesday hopefully I will be able to comment more on that
terryforsythe
Major Contributor
Where did you buy the 10mm felt? I want to replace the fiberglass inside my speakers with felt.
- Thread Starter
- #40
Not sure it will help but I get them from here: https://zajcsillapitas.net/webshop/product/ovf-soft-1000x1500mm_12
