Here is what I came up with for a TL design for the PTT6.5. Achieves nominal 84.8dB at 2.83v and 1m with -3dB at 36Hz to 42Hz depending on stuffing/damping.
Simple Passive Harsch XO Using PTT6.5 and RS28F in a Waveguide
Simple Passive Harsch XO Using PTT6.5 and RS28F in a Waveguide
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I thought mainframe99 made a passing remark in this thread, the sort of thing where Claus doesnt want to start making promises nor have you wander off and buy something elses 😉
Cheers
all hail our new Danish audio kings Didn't finish. Hot day so started late and the router jig slipped while making the front baffle so took longer to correct the error. And front still needs flush trim and chamfer. Might have to redo the baffle. Luckily it was designed to be removable for experimentation.
I swear my next speakers will be CNCed!
Put everything together to pose for the picture. Purifi 6.5, SB passive radiators, and B&W tweeters with 3D printed housing/ front plate.
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Nice work, Jmpmarsh. Looking forward to your measurements and XO details.
I finalized my XO in a PCB with better components and it made a difference. A flat copper foil inductor and Mills resistor, seems to have smoother response in the mid bass.
Now that the performance above 100Hz is sorted out in the test box with passive radiators, I am moving onto the TL cabinet to handle the below 100Hz frequencies. Hopefully extend to 36Hz smoothly and efficiently.
I finalized my XO in a PCB with better components and it made a difference. A flat copper foil inductor and Mills resistor, seems to have smoother response in the mid bass.
Now that the performance above 100Hz is sorted out in the test box with passive radiators, I am moving onto the TL cabinet to handle the below 100Hz frequencies. Hopefully extend to 36Hz smoothly and efficiently.
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The Purifi woofer's performance has been so good that I've gone a bit mental and am stepping the tweeter game up, and attempting to get rid of the bass reflex ports. Today that package arrived;
Jmpsmash's progress got me excited and modelling the 5x8 PR's works quite well so I grabbed some, not to mention the odd shape goes with the odd woofer. 'March Audio' (@another forum) has teased a new speaker that got me hyped about the tweeter. So this weekend I should have this lot running. I've been using XRK971's harsch time aligned crossover with great success - see his thread - I really recommend you give it a go if you have a DSP XO.
Jmpsmash's progress got me excited and modelling the 5x8 PR's works quite well so I grabbed some, not to mention the odd shape goes with the odd woofer. 'March Audio' (@another forum) has teased a new speaker that got me hyped about the tweeter. So this weekend I should have this lot running. I've been using XRK971's harsch time aligned crossover with great success - see his thread - I really recommend you give it a go if you have a DSP XO.
Here are some raw measurements before any box tuning.
Here is the impedance plot. Box resonance is a bit higher than driver. Will have to tune the PRs.
Here is the near field FR plot of the Purifi and one of the 2 SB PR.
My guess is that I can add a few grams to low the resonance a bit more?
There are also 2 dips at 460/890Hz. Those corresponds to the depth and the width of the box. Need to add some dampening.
Here is the impedance plot. Box resonance is a bit higher than driver. Will have to tune the PRs.
Here is the near field FR plot of the Purifi and one of the 2 SB PR.
My guess is that I can add a few grams to low the resonance a bit more?
There are also 2 dips at 460/890Hz. Those corresponds to the depth and the width of the box. Need to add some dampening.
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2 PR's per woofer. I think the Vd of the purifi (max) is about 193 cm3 and the vd max of this PR is 195cm3 so it works out on paper
well I can confirm that it will work. I just hooked it up and blasted some organ and the 2 PRs held up fine even when the Purifi was pumping hard, at parts the Purifi even went beyond xmax, scared the crap out of me.
not much in terms of listening nor impressions as this is before fine tuning.
Is that the Bliesma? You really did splurge!
I am deciding between either the T25 or the Transducer Lab N26CR2. I heard the Be version of the Transducer Lab and really liked it. In either case, they are all sold out. I cannot find the Bliesma in stock anywhere at the moment. And only the Ceramic version of the Transducer Lab is in stock.
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Thanks! I did not notice the Bliesma! Wow - nice stuff mainfrme!
Great measurements Jmpsmash! Are you doing passive or active XO? Try the Harsch if you are DSP'ing it.
That SBA PR looks ideally suited for this build.
I have wondered about that too - my test box has them on the back so not as much a problem. But can definitely hear some mids radiating out. Some stuffing will help but not eliminate and will dampen the bass too much. A TL would be better in the respect. Btw, complete CAD drawn plans for the TL design are now available here, including the STL file for the WG300 to RS28F adapter.
In Jmpsmash's graph, you can see the peaks at 210Hz, 270Hz, 470Hz, 1400Hz and 1700Hz maybe -15dB to -25dB below the main output (assuming scale is the same).
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good point about the mid-frequency leak. a -15dB leak will certainly be audible and unpleasant at those frequencies. Both the hificompass and the Purifi official build (despite being a ported, they probably had the same design for their PR testing) have a internal barrier that doubles as internal framing. I plan to add that to my box and compare the measurements. Along with some absorption for the box dimension resonance should control those leak better.
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Yes. I will definitely try, it looks very interesting! I have active DSP crossover. I also plan to build a passive one at some point. But before that I need to sort out the tweeter and refine the cabinet.