Someone (poor guy) I think is trying to make a business out of selling the reference build as a complete speaker without thinking it through or really testing the speaker before sending it out. Not suprising it's suboptimal.
It's still just a small woofer
Might be awesome in many ways, but it cant cheat physics
Here’s my build, in a 0.7cu ft (19.5L) box.
Ported, 2.5” x 8.5”
Fb: 39Hz
F3: 38Hz. F10:30Hz
The port is on the longer side, but no longer than what’s needed for the SEAS L18RNX/P, which was previously in this cabinet.
Here’s some measurements- port measurement not included; but the dip around 40Hz indicates the minimum woofer motion; where the rear firing port takes over. One fine sunny windless day I’ll take sound ground plane measurements to validate the anechoic response.
There’s a dip and peak at 2.5Khz and 4Khz due the baffle edge diffraction effect on the tweeter, but it’s not audible as it disappears off axis. If I take a 19-25mm rounding over bit to the cabinet, it will be gone, but it looks ugly IMHO.
In-room theres output to the thirties (Hz). Neighbours complains “Turn down your Subwoofers!”
“What subwoofers? I don’t have any”
Neighbors get more irate...
Ported, 2.5” x 8.5”
Fb: 39Hz
F3: 38Hz. F10:30Hz
The port is on the longer side, but no longer than what’s needed for the SEAS L18RNX/P, which was previously in this cabinet.
Here’s some measurements- port measurement not included; but the dip around 40Hz indicates the minimum woofer motion; where the rear firing port takes over. One fine sunny windless day I’ll take sound ground plane measurements to validate the anechoic response.
There’s a dip and peak at 2.5Khz and 4Khz due the baffle edge diffraction effect on the tweeter, but it’s not audible as it disappears off axis. If I take a 19-25mm rounding over bit to the cabinet, it will be gone, but it looks ugly IMHO.
In-room theres output to the thirties (Hz). Neighbours complains “Turn down your Subwoofers!”
“What subwoofers? I don’t have any”
Neighbors get more irate...
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To me the railing on the right suggest a void as if the room is a mezzanine.?
tktran303,
Nice job retrofitting a cabinet from a previous project. And from what you have shared, the LF is not underwhelming in any way.
You plan to keep them as is, or eventually move them over to a new enclosure?
it’s built using an existing cabinet so I could brush up my analog filter design skills, whilst stuck in 2 weeks Covid quarantine, so I couldn’t build my own cabinet.
If I built it again I’d cram it in the smallest cabinet I could get away with, but still ensure big bass, no subwoofer required (for music; my requirements is F10 ~40Hz for music)
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Forgot to add; For those concerned that the port is too long a down firing port is always an option, to fit in into the cabinet. I’ve had success previously:
Statements II - A musical evolution! - Page 2
Statements II - A musical evolution! - Page 2
Router like this is similar in price to a nice set of speakers - $5k USD would get you there, especially at a DIY level where speed isn't important. Go slowly and a low power spindle can cut like this.
Wow! Distortion is about 55 dB down from 100 Hz, maybe more. Was the mic calibrated for absolute SPL? how far was it from the speaker? or what was the drive level?
- 55 dB is about 0.05% distortion. It's curious that it should be like this across the band. Maybe you can turn up the level so we can actually see the components?
Here is the speaker crossover version 3.
As modelled: 0/40/80 degrees
As measured: ~0/40/80 degrees (eye balled)
Conditions:
Drive level: for SPL 90dB @1m using pink noise
Measurement height 2.00m (laser +/- 2mm)
Measurement distance was taken at slight less than 1m (0.80m) to maximise the window length to 9ms, giving accuracy down to 120Hz
Tweeter is the original SEAS Millennium, T25CF002, something I had on hand.
This tweeter has HIGHER distortion between 2-3KHz than the Purifi.
So I will need to change tweeters to something that can cross low AND have equally low distortion as the Purifi.
As modelled: 0/40/80 degrees
As measured: ~0/40/80 degrees (eye balled)
Conditions:
Drive level: for SPL 90dB @1m using pink noise
Measurement height 2.00m (laser +/- 2mm)
Measurement distance was taken at slight less than 1m (0.80m) to maximise the window length to 9ms, giving accuracy down to 120Hz
Tweeter is the original SEAS Millennium, T25CF002, something I had on hand.
This tweeter has HIGHER distortion between 2-3KHz than the Purifi.
So I will need to change tweeters to something that can cross low AND have equally low distortion as the Purifi.
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Hello Capslock,
Sorry I didn’t save the drive level. The measurement distance was 50cm so it’s fairly low stress for the driver (79dB @1m) because it was an indoor measurement and I try not to bother the family.
So i wouldn’t take it as final representative of 1m or 2.5-3m; which is what I design for.
But have you seen this?
Purifi PTT6.5W04-01A | HiFiCompass
At 8V drive level 315mm, that 98dB on a 1650x850 mm baffle.
all distortion components are -55dB and below...
Sorry I didn’t save the drive level. The measurement distance was 50cm so it’s fairly low stress for the driver (79dB @1m) because it was an indoor measurement and I try not to bother the family.
So i wouldn’t take it as final representative of 1m or 2.5-3m; which is what I design for.
But have you seen this?
Purifi PTT6.5W04-01A | HiFiCompass
At 8V drive level 315mm, that 98dB on a 1650x850 mm baffle.
all distortion components are -55dB and below...
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I agree. The PTT6.5 has lower distortion than any other driver I have measured in this range. Those numbers are all real - it can be used as a low distortion midrange up to 5.5kHz.
I have been working on a new floorstanding TL for the Purifi (top driver) with tweeter in a waveguide (lower driver):
I have been working on a new floorstanding TL for the Purifi (top driver) with tweeter in a waveguide (lower driver):
