• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Considerations for designing a speaker cabinet with sim software (4 ohm Purifi 6.5 woofer target)

DDF

Addicted to Fun and Learning
Joined
Dec 31, 2018
Messages
565
Likes
1,042
#1
Taking full advantage of the Purifi's main benefits requires some unsavory trade offs:
- TS parameters aim for extreme bass reach to take advantage of the very linear design. This requires very expensive passive radiators
- As Purifi claim in this and this paper, its the IM distortion to watch out for, not harmonic distortion. The main benefit of its very low IM design is fully milked trying to operate the driver higher in frequency, but its off axis radiation is nothing special and directivity matching isn't great enough to take full advantage.

The Purifi tech would work better in a 5" designed for mid/woofer duties. Imagine the modern LS35A that Purifi's tech could achieve?

To me, a truly modern system with the fewest trade offs is one that uses separate sub woofer(s) to allow the mains best placement for imaging, and the subs best placement to control room modes. Toss in as small a box size as possible for better visual integration into the room.

The Purifi 6.5's drawbacks can still be avoided and the modern benefits attained by instead designing it in a small sealed box. Running a quick simulation in Unibox shows a very doable small sealed design:
1606325223924.png


Being sealed also allows heavy fill to clean up box modes, which was included in the simulation. No "port leakage" or mid range ripples.

Being a small box puts some limits on the tweeter faceplate size that will fit. Luckily, a a quick look shows the Seas DXT tweeter used in the Kii Three provides a nice fit, off axis directivity control with its modest waveguide faceplate, and ability to cross low and hard to give great directivity match.

A quick sim in boxycad (subtracting volume of driver and crossover components) with standard 3/4" MDF at 6L effective volume gives (just add some 1" roundovers) a nice pleasingly small box:
1606325416421.png

A 150W amp will deliver ~ 102 dB SPL in the mid range (subtract BDC and crossover EQ from the curve below), and a nice 70Hz F3 to cross to subs.
1606325761165.png


Given its linear design, there's no need for a high pass to protect the woofer, further simplifying integration with a sub. Here's is the displacement required at 150W. It stays within its linear xmax over its intended operating range and just stays below its maximum available throw (14.7mm) at all frequencies.

1606325891293.png


Running a proper second order high pass for integrating with the sub would take this all pretty much below 10mm, but given the purifi's low IM, I don't think is necessary.

Compare this to a typical vented design 3 times the size (if you could even fit a vent...). Not so pretty
1606325949613.png


The sealed design takes advantage of the Purifi's real benefits over other drivers, long clean linear throw and very low IM distortion, and does it in a nice small box.

Caveat: I still want to calculate the distortion created by the compression of the air itself in such a small box, but I whipped this off in a quick available lunch hour
 
Last edited:

Dennis Murphy

Addicted to Fun and Learning
Technical Expert
Joined
Mar 17, 2020
Messages
543
Likes
2,282
#2
Taking full advantage of the Purifi's main benefits requires some unsavory trade offs:
- TS parameters aim for extreme bass reach to take advantage of the very linear design. This requires very expensive passive radiators
- As Purifi claim in this and this paper, its the IM distortion to watch out for, not harmonic distortion. The main benefit of its very low IM design is fully milked trying to operate the driver higher in frequency, but its off axis radiation is nothing special and directivity matching isn't great enough to take full advantage.

The Purifi tech would work better in a 5" designed for mid/woofer duties. Imagine the modern LS35A that Purifi's tech could achieve?

To me, a truly modern system with the fewest trade offs is one that uses separate sub woofer(s) to allow the mains best placement for imaging, and the subs best placement to control room modes. Toss in as small a box size as possible for better visual integration into the room.

The Purifi 6.5's drawbacks can still be avoided and the modern benefits attained by instead designing it in a small sealed box. Running a quick simulation in Unibox shows a very doable small sealed design:
View attachment 95799

Being sealed also allows heavy fill to clean up box modes, which was included in the simulation. No "port leakage" or mid range ripples.

Being a small box puts some limits on the tweeter faceplate size that will fit. Luckily, a a quick look shows the Seas DXT tweeter used in the Kii Three provides a nice fit, off axis directivity control with its modest waveguide faceplate, and ability to cross low and hard to give great directivity match.

A quick sim in boxycad (subtracting volume of driver and crossover components) with standard 3/4" MDF at 6L effective volume gives (just add some 1" roundovers) gives a nice pleasingly small box:
View attachment 95800
A 150W amp will deliver ~ 102 dB SPL in the mid range (subtract BDC and crossover EQ from the curve below), and a nice 70Hz F3 to cross to subs.
View attachment 95801

Given its linear design, there's no need for a high pass to protect the woofer, further simplifying integration with a sub. Here's is the displacement required at 150W. It stays within its linear xmax over its intended operating range and just stays below its maximum available throw (14.7mm) at all frequencies.

View attachment 95802

Running a proper second order high pass for integrating with the sub would take this all pretty much below 10mm, but given the purifi's low IM, I don't think is necessary.

Compare this to a typical vented design 3 times the size (if you could even fit a vent...). Not so pretty
View attachment 95803

The sealed design takes advantage of the Purifi's real benefits over other drivers, long clean linear throw and very low IM distortion, and does it in a nice small box.

Caveat: I still want to calculate the distortion created by the compression of the air itself in such a small box, but I whipped this off in a quick available lunch hour
Very interesting. I wouldn't want to be constrained in my choice of tweeters, but that's easily solved by using a slightly taller box with extra thick bracing, or a thick mdf block on the bottom, shallower depth, or whatever to use up the added volume.
 

617

Major Contributor
Forum Donor
Joined
Mar 18, 2019
Messages
1,260
Likes
2,702
Location
Somerville, MA
#3
Very interesting. I wouldn't want to be constrained in my choice of tweeters, but that's easily solved by using a slightly taller box with extra thick bracing, or a thick mdf block on the bottom, shallower depth, or whatever to use up the added volume.
Dennis any intuition as to use in a transmission line? Not small at that point of course. The more I think about it, the more I think this is a very esoteric driver with limited utility.
 

digitalfrost

Addicted to Fun and Learning
Forum Donor
Joined
Jul 22, 2018
Messages
671
Likes
1,054
Location
Palatinate, Germany
#5
To me, a truly modern system with the fewest trade offs is one that uses separate sub woofer(s) to allow the mains best placement for imaging, and the subs best placement to control room modes. Toss in as small a box size as possible for better visual integration into the room.

The Purifi 6.5's drawbacks can still be avoided and the modern benefits attained by instead designing it in a small sealed box. Running a quick simulation in Unibox shows a very doable small sealed design:
View attachment 95799

Being sealed also allows heavy fill to clean up box modes, which was included in the simulation. No "port leakage" or mid range ripples.

Being a small box puts some limits on the tweeter faceplate size that will fit. Luckily, a a quick look shows the Seas DXT tweeter used in the Kii Three provides a nice fit, off axis directivity control with its modest waveguide faceplate, and ability to cross low and hard to give great directivity match.
That's funny. I use ER18DXT with the DXT tweeter and a Seas ER18 7" woofer (which also has low IMD). Contratry to the original, I built them closed with gives an f3 of ~ 80hz because I use separate subwoofers. Seems I was on the right track :D
 
Last edited:
OP
DDF

DDF

Addicted to Fun and Learning
Joined
Dec 31, 2018
Messages
565
Likes
1,042
Thread Starter #6
Familiar company, nice to see you both, Dave and Dennis...
Hope you're doing well Wolf

Very interesting. I wouldn't want to be constrained in my choice of tweeters, but that's easily solved by using a slightly taller box with extra thick bracing, or a thick mdf block on the bottom, shallower depth, or whatever to use up the added volume.
No major constraints. I just checked the first good tweeter I thought would work, I'm sure there are several options. Additionally, less stuffing could be used for the same alignment and a slightly taller box to accomodate more tweeters. I wouldnt drop Q much lower.
 

ctrl

Addicted to Fun and Learning
Joined
Jan 24, 2020
Messages
807
Likes
2,584
Location
.de, DE, DEU
#7
A quick sim in boxycad (subtracting volume of driver and crossover components) with standard 3/4" MDF at 6L effective volume gives (just add some 1" roundovers) gives a nice pleasingly small box:
No major constraints. I just checked the first good tweeter I thought would work, I'm sure there are several options. Additionally, less stuffing could be used for the same alignment and a slightly taller box to accomodate more tweeters. I wouldnt drop Q much lower.
Would suggest to separate the tweeter from the woofer with a separate internal enclosure - because of the high internal pressure from the woofer and there are tweeters that are not (reliably) sealed. This internal chamber should be large enough to accommodate the most common tweeters.

Probably a design proposal with symmetrically arranged drivers will be more appealing. To improve the horizontal radiation, lateral bevels should be used.

If it is requested, I can also simulate the loudspeaker for one or the other tweeter - this will save a lot of prototypes.
 

tktran303

Active Member
Joined
Mar 27, 2019
Messages
282
Likes
401
#8
There are a lot of solutions for this midwoofer.

Engineering design is a balance of tradeoffs. I agree with Dave; a small sealed 1/4 cu ft if you want a big woofer stuffed in a tiny box (or if you plan to use subwoofers)

My own prototype design is a 3/4 cu ft vented;
A single straight 2.5” ID x 8.5” circular port tunes it to 40Hz. This port easily fits in the cabinet without bends requiring a 3 piece construction like the Purifi SPK5 example. The downside is that my cabinet must be deeper or taller to accomodate said port.

When tuned to 40Hz in this larger cabinet, when compared to a lower tuning frequency (like 28-34Hz), is that gives higher output in the 50Hz region ( punchier bass ) and higher power handling in this region where there’s still a lot of musical content, but then lower power handling below 40Hz. Again, trade offs.

With a straightforward cabinet I can focus my energies on the crossover. I haven’t finalised or fixed the crossover point, but it’s doing ok around 2.1Khz. The final point may be around it will be around 1.5-2.5Khz; balancing out factors like smooth off axis response, listening window response, phase response near crossover region, tweeter power handling, number of components in the passive crossover.

And we don’t need waveguides or ribbons or AMT. Thats just a choice that Purifi made for their example. I think people are confusing the SPK5 example as some kind of reference or golden sample. It was not designed or intended as such.

I’m using an off the shelf SEAS Millenium tweeter, which can go down below 2KHz. Like the Revelator D2905-9900 or Dynaudio Esotar, still one of the finest tweeters, although cost has crept up over the years.

There may be better values out there eg. SB29SDAC or more fancy or fashionable materials in 2020 (Beryllium, Ceramic, Carbon fiber, Diamond)

smooth frequency response
Low harmonic and IM distortion
High Xmax and power handling
Low sensitivity.

You can’t have it all.

tradeoffs...
 
Last edited:
Joined
Nov 20, 2018
Messages
63
Likes
77
Location
Perth Ontario
#10
Taking full advantage of the Purifi's main benefits requires some unsavory trade offs:
- TS parameters aim for extreme bass reach to take advantage of the very linear design. This requires very expensive passive radiators
- As Purifi claim in this and this paper, its the IM distortion to watch out for, not harmonic distortion. The main benefit of its very low IM design is fully milked trying to operate the driver higher in frequency, but its off axis radiation is nothing special and directivity matching isn't great enough to take full advantage.

The Purifi tech would work better in a 5" designed for mid/woofer duties. Imagine the modern LS35A that Purifi's tech could achieve?

To me, a truly modern system with the fewest trade offs is one that uses separate sub woofer(s) to allow the mains best placement for imaging, and the subs best placement to control room modes. Toss in as small a box size as possible for better visual integration into the room.

The Purifi 6.5's drawbacks can still be avoided and the modern benefits attained by instead designing it in a small sealed box. Running a quick simulation in Unibox shows a very doable small sealed design:
View attachment 95799

Being sealed also allows heavy fill to clean up box modes, which was included in the simulation. No "port leakage" or mid range ripples.

Being a small box puts some limits on the tweeter faceplate size that will fit. Luckily, a a quick look shows the Seas DXT tweeter used in the Kii Three provides a nice fit, off axis directivity control with its modest waveguide faceplate, and ability to cross low and hard to give great directivity match.

A quick sim in boxycad (subtracting volume of driver and crossover components) with standard 3/4" MDF at 6L effective volume gives (just add some 1" roundovers) gives a nice pleasingly small box:
View attachment 95800
A 150W amp will deliver ~ 102 dB SPL in the mid range (subtract BDC and crossover EQ from the curve below), and a nice 70Hz F3 to cross to subs.
View attachment 95801

Given its linear design, there's no need for a high pass to protect the woofer, further simplifying integration with a sub. Here's is the displacement required at 150W. It stays within its linear xmax over its intended operating range and just stays below its maximum available throw (14.7mm) at all frequencies.

View attachment 95802

Running a proper second order high pass for integrating with the sub would take this all pretty much below 10mm, but given the purifi's low IM, I don't think is necessary.

Compare this to a typical vented design 3 times the size (if you could even fit a vent...). Not so pretty
View attachment 95803

The sealed design takes advantage of the Purifi's real benefits over other drivers, long clean linear throw and very low IM distortion, and does it in a nice small box.

Caveat: I still want to calculate the distortion created by the compression of the air itself in such a small box, but I whipped this off in a quick available lunch hour
Nice bunch of thinking Dave.

I have worked with a few clients on sealed enclosures using a similar sized driver. A fully dampened enclosure can have really revealing effects on the sound, or should I say lack of sound of an enclosure.
 

Lorenzo74

Senior Member
Joined
Nov 17, 2019
Messages
300
Likes
234
Location
Italy, Rome
#11
Ah, thanks. So the general phenomenon is just port resonance. Wonder why they didn't go with their own PR unit then, instead of a vent.
when the spk5 came out, the PR was not yet released. Pls Consider the spk4 (previous design has even shorter (but straight) port and different crossover freq.
they choose AMT mainly for the capability to sustain high SPL, the overall purpose was to demostrate a 2 way can play very low, very loud and clean.
maybe this is the reason later design (marchaudio), leveraging on PR will show better graphs and ASR score.
and as just said, imagine kii three just with ET amp and Purifi drivers...
We’ll see.
best
L.
 
Last edited:

GimeDsp

Active Member
Joined
Oct 30, 2020
Messages
101
Likes
89
Location
Earth
#12
The crossover is the SPK5 Crossover Kit ordered from Purifi and assembled by me.
Building 3 pairs is awsome!
I have done many "multiples" projects in the past and it was never "fun". Results are great but by the last one I am burnt out!
Great Job!
 
Joined
Nov 13, 2020
Messages
23
Likes
10
#13
I would have to agree with Amirm - the Purifi has low distortion BUT lacks impact - you just don't feel it.
And it does need EQing (30 band) to push the lower frequencies. and fix the crossover/ vocal range.
I am crossing it at 1300Hz with a 800w [peak] Pro-Ribbon, so I am cutting the Purifi before the problem region starts.
It does make the ribbon sound fantastic compared with using the stock 18 Sound woofer.

With Master Audio playing it sounds breathtaking and the sound stage is huge - though that's mainly due to the Pro-Ribbon.
My criticism of the Purifi used in this way is the lack of punch/ impact, it just seems to drop off at 3m and its poor on vocals.
 
Last edited:

tktran303

Active Member
Joined
Mar 27, 2019
Messages
282
Likes
401
#14
I wonder where you felt the lack punch or impact came from? I mean, at what frequency.

My design is somewhere in the realm of 81.5-82dB / 2.83V. That is very low for a 6.5" woofer in 3/4 cu foot box.
 
Joined
Nov 13, 2020
Messages
23
Likes
10
#15
I wonder where you felt the lack punch or impact came from? I mean, at what frequency.

My design is somewhere in the realm of 81.5-82dB / 2.83V. That is very low for a 6.5" woofer in 3/4 cu foot box.
It seems to be across the board in the lower ranges - you hear it but don't feel it.
 

Rick Sykora

Major Contributor
Forum Donor
Joined
Jan 14, 2020
Messages
1,232
Likes
1,848
Location
Stow, Ohio USA
#16
Taking full advantage of the Purifi's main benefits requires some unsavory trade offs:
- TS parameters aim for extreme bass reach to take advantage of the very linear design. This requires very expensive passive radiators
- As Purifi claim in this and this paper, its the IM distortion to watch out for, not harmonic distortion. The main benefit of its very low IM design is fully milked trying to operate the driver higher in frequency, but its off axis radiation is nothing special and directivity matching isn't great enough to take full advantage.

The Purifi tech would work better in a 5" designed for mid/woofer duties. Imagine the modern LS35A that Purifi's tech could achieve?

To me, a truly modern system with the fewest trade offs is one that uses separate sub woofer(s) to allow the mains best placement for imaging, and the subs best placement to control room modes. Toss in as small a box size as possible for better visual integration into the room.

The Purifi 6.5's drawbacks can still be avoided and the modern benefits attained by instead designing it in a small sealed box. Running a quick simulation in Unibox shows a very doable small sealed design:
View attachment 95799

Being sealed also allows heavy fill to clean up box modes, which was included in the simulation. No "port leakage" or mid range ripples.

Being a small box puts some limits on the tweeter faceplate size that will fit. Luckily, a a quick look shows the Seas DXT tweeter used in the Kii Three provides a nice fit, off axis directivity control with its modest waveguide faceplate, and ability to cross low and hard to give great directivity match.

A quick sim in boxycad (subtracting volume of driver and crossover components) with standard 3/4" MDF at 6L effective volume gives (just add some 1" roundovers) a nice pleasingly small box:
View attachment 95800
A 150W amp will deliver ~ 102 dB SPL in the mid range (subtract BDC and crossover EQ from the curve below), and a nice 70Hz F3 to cross to subs.
View attachment 95801

Given its linear design, there's no need for a high pass to protect the woofer, further simplifying integration with a sub. Here's is the displacement required at 150W. It stays within its linear xmax over its intended operating range and just stays below its maximum available throw (14.7mm) at all frequencies.

View attachment 95802

Running a proper second order high pass for integrating with the sub would take this all pretty much below 10mm, but given the purifi's low IM, I don't think is necessary.

Compare this to a typical vented design 3 times the size (if you could even fit a vent...). Not so pretty
View attachment 95803

The sealed design takes advantage of the Purifi's real benefits over other drivers, long clean linear throw and very low IM distortion, and does it in a nice small box.

Caveat: I still want to calculate the distortion created by the compression of the air itself in such a small box, but I whipped this off in a quick available lunch hour
Am pondering a build for Amir to test. As we live pretty much cross country, keeping the box small helps shipping cost on both ends. So was contemplating a sealed design as you posted and so ran the sim in Bassbox Pro.

Using the published T/S parameters and matching your posted box info, the f3 from Bassbox is more like 94 Hz. This aligns with my expectation for a low Qts driver like this. Since this is quite different than your Unibox sim, before I consider building, can you explain how you are getting an f3 of 68 Hz? Thanks!
 
Last edited:
Joined
Jun 16, 2020
Messages
38
Likes
17
#17
Am pondering a build for Amir to test. As we live pretty much cross country, keeping the box small helps shipping cost on both ends. So was contemplating a sealed design as you posted and so ran the sim in Bassbox Pro.

Using the published T/S parameters and matching your posted box info, the f3 from Bassbox is more like 94 Hz. This aligns with my expectation for a low Qts driver like this. Since this is quite different than your Unibox sim, before I consider building, can you explain how you are getting an f3 of 68 Hz? Thanks!
It's very obvious it's an broken speaker.Should never been reviewed.
 
OP
DDF

DDF

Addicted to Fun and Learning
Joined
Dec 31, 2018
Messages
565
Likes
1,042
Thread Starter #18
Am pondering a build for Amir to test. As we live pretty much cross country, keeping the box small helps shipping cost on both ends. So was contemplating a sealed design as you posted and so ran the sim in Bassbox Pro.

Using the published T/S parameters and matching your posted box info, the f3 from Bassbox is more like 94 Hz. This aligns with my expectation for a low Qts driver like this. Since this is quite different than your Unibox sim, before I consider building, can you explain how you are getting an f3 of 68 Hz? Thanks!
Thanks for posting your bassbox results. That'll be an interesting build, good luck and please keep us posted. If you do the build, you'll need to make changes to the crossover for best results.

I know my sim was correct, so I looked into the difference. I used the Purifi datasheet published at Hificompass (v0.95) here. The Purifi site here has an updated spec sheet (v.1.10)

Purifi changed the TS parameters. It looks like the spider's production values differed from early prototypes (not uncommon).

v0.95 at Hificompass:
1606505320830.png

V1.10 at Purifi:
1606505294982.png


This does change the outcome, calling for a few small adjustments. The result is still great for sub integration:
1606508300396.png
1606509000107.png


Changes needed due to updated TS parameters:
  • Reduce effective box size from 6L effective to 5.7L effective. This requires shortening the depth by only a quarter inch, to:
1606508378126.png


By "effective" I mean add volume to the real box for driver, braces etc.
  • The other was a slight decrease in low pass inductor gauge so that total amplifier o/p impedance (damping factor), speaker wire resistance and inductor resistance is 0.7 ohms. I'd previously assumed 0.5 ohms. Like a lot of "tweaks", large low gauge "audiophile" inductors can often make things worse and this is an application where thinner gauge, cheaper inductors give better performance. The cost was a 0.3 dB reduction in sensitivity, but the trade off is well worth it. When using low impedance drivers and very small box sizes, its critical to properly account for the source impedance or the box size won't give the results you think.
Lining the box instead of heavy fill can further reduce the F3 a bit, to:
1606508785216.png


but IME testing different stuffing types and density, the benefit of heavy box stuffing in cleaning up the mid range far outweighs the slight increase in bass available near Fb when just lining walls, especially when you factor in the huge differences in bass response shown with even minor changes in speaker or listening position.

The reason bassbox gave an F3 of 94 Hz might be because the resistance wasn't factored in, or its box stuffing assumptions might differ from Unibox.

I once looked into the math Unibox uses and confirmed its accurate to the Benson and Bullock models (that evolved from Thiele Small) while some other popular box model software available back in those old days weren't (don't know about bassbox though). I also confirmed through builds and near field measurements that Unibox assumes pretty realistic values for the effects of box stuffing (Qa), if using quality fill.

I'm confident in Unibox's predictions and that these sims are good, but thanks for pointing out the difference! It led to the realization TS params had changed.
 

Attachments

Rick Sykora

Major Contributor
Forum Donor
Joined
Jan 14, 2020
Messages
1,232
Likes
1,848
Location
Stow, Ohio USA
#19
Thanks for posting your bassbox results. That'll be an interesting build, good luck and please keep us posted. If you do the build, you'll need to make changes to the crossover for best results.

I know my sim was correct, so I looked into the difference. I used the Purifi datasheet published at Hificompass (v0.95) here. The Purifi site here has an updated spec sheet (v.1.10)

Purifi changed the TS parameters. It looks like the spider's production values differed from early prototypes (not uncommon).

v0.95 at Hificompass:
View attachment 96160
V1.10 at Purifi:
View attachment 96159

This does change the outcome, calling for a few small adjustments. The result is still great for sub integration:
View attachment 96171 View attachment 96174

Changes needed due to updated TS parameters:
  • Reduce effective box size from 6L effective to 5.7L effective. This requires shortening the depth by only a quarter inch, to:
View attachment 96172

By "effective" I mean add volume to the real box for driver, braces etc.
  • The other was a slight decrease in low pass inductor gauge so that total amplifier o/p impedance (damping factor), speaker wire resistance and inductor resistance is 0.7 ohms. I'd previously assumed 0.5 ohms. Like a lot of "tweaks", large low gauge "audiophile" inductors can often make things worse and this is an application where thinner gauge, cheaper inductors give better performance. The cost was a 0.3 dB reduction in sensitivity, but the trade off is well worth it. When using low impedance drivers and very small box sizes, its critical to properly account for the source impedance or the box size won't give the results you think.
Lining the box instead of heavy fill can further reduce the F3 a bit, to:
View attachment 96173

but IME testing different stuffing types and density, the benefit of heavy box stuffing in cleaning up the mid range far outweighs the slight increase in bass available near Fb when just lining walls, especially when you factor in the huge differences in bass response shown with even minor changes in speaker or listening position.

The reason bassbox gave an F3 of 94 Hz might be because the resistance wasn't factored in, or its box stuffing assumptions might differ from Unibox.

I once looked into the math Unibox uses and confirmed its accurate to the Benson and Bullock models (that evolved from Thiele Small) while some other popular box model software available back in those old days weren't (don't know about bassbox though). I also confirmed through builds and near field measurements that Unibox assumes pretty realistic values for the effects of box stuffing (Qa), if using quality fill.

I'm confident in Unibox's predictions and that these sims are good, but thanks for pointing out the difference! It led to the realization TS params had changed.
Thanks for the update.

Even with the T/S params matched, was not getting much better results. Bassbox Pro does not let you tweak every aspect of the design, though I could set Ql to 50 (default is 20). Afterwards, I simply asked it to calculate an optimal box to achieve a f3 of 70 Hz. It responded that it could not meet that target. I have lots of experience with Bassbox in creating vented designs and generally the sim is pretty good. I decided to turn off the box fill aspect of the sim and did get down to f3 of 80 Hz. As Madisound distributes the driver domestically and I do not have a driver in hand, I checked their website. They have yet another set of T/S pararms and are claiming f3 of 87 Hz for a comparably sized box.

Just to be clear, not claiming any particular sim is more accurate, but the premise of ASR is science and so results are expected to be repeatable. We have lessened the gap, but in this case, 10 Hz of f3 is not within the margin of error I think is acceptable. If you have other suggestions, let me know. I will post the some more of the Bassbox screens and results later. Have to go get some dinner. :cool:
 
Last edited:
OP
DDF

DDF

Addicted to Fun and Learning
Joined
Dec 31, 2018
Messages
565
Likes
1,042
Thread Starter #20
Thanks for the update.

Even with the T/S params matched, was not getting much better results. Bassbox Pro does not let you tweak every aspect of the design, though I could set Ql to 50 (default is 20). Afterwards, I simple as it to calculating an optimal box to achieve a f3 of 70 Hz. It responded that it could not meet that target. I have lots of experience with Bassbox in creating vented designs and generally the sim is pretty good. I decided to turn off the box fill aspect of the sim and did get down to f3 of 80 Hz. As Madisound distributes the driver domestically and I do not have a driver in hand, I checked their website. They have yet another set of T/S pararms and are claiming f3 of 87 Hz for a comparably sized box.

Just to be clear, not claiming any particular sim is more accurate, but the premise of ASR is science and so results are expected to be repeatable. We have lessened the gap, but in this case, 10 Hz of f3 is not within the margin of error I think is acceptable. If you have other suggestions, let me know. I will post the some more of the Bassbox screens and results later. Have to go get some dinner. :cool:
What did you assume for in line resistance and which TS params did you assume? No way either program is this far apart unless the driver or design assumptions differ. I listed mine in my previous post. How did your assumptions differ?
 
Top Bottom