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ROAR with Helmholtz front resonator
ROAR with Helmholtz front resonator
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Old 18th October 2018, 02:55 PM   #31
Circlomanen is offline Circlomanen  Sweden
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There is no serious acronym for ROAR. We joked around with different names and ROAR just kind of stuck with the project. I used to call it TPQWR for Tapped Pipe Quarter Wave Resonator.
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Old 18th October 2018, 05:50 PM   #32
BP1Fanatic is offline BP1Fanatic  United States
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Quote:
Originally Posted by Circlomanen View Post
Thanks papasteack for the idea to simulate the TPBP10 as TH1 in Hornresp!
It makes it much easier to compare with actual measurements in REW.

Attachment 710022

This is how it compares with in mouth measurement indoors.
Nice car audio curve!
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Old 18th October 2018, 06:32 PM   #33
academia50 is offline academia50  Argentina
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Quote:
Originally Posted by Circlomanen View Post
There is no serious acronym for ROAR. We joked around with different names and ROAR just kind of stuck with the project. I used to call it TPQWR for Tapped Pipe Quarter Wave Resonator.
Ahhh, rightly so, we all have our deductive limitations, but I was beginning to believe that my case was very serious

thank you, it has been a very important clarification for me
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Old 18th October 2018, 06:45 PM   #34
UPitt is offline UPitt
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Originally Posted by Circlomanen View Post
Do you have (reasonable) reliable data on those drivers?
Currently, I don't have any products for measuring the drivers right now other than a mic and I'm away from home at college right now anyways. Some people at AVS forum used this sub and used the TS parameters from this datasheet. https://www.hobbielektronika.hu/foru....php?id=260785

VOICE-COIL DC RESISTANCE: REVC (OHMS) . . . . . . . 3.6
VOICE-COIL INDUCTANCE @ 1 KHZ: LEVC (MH) . . . . . . . 2.57
SD (cm2) . . . . . . . 551.00
MOTOR FORCE FACTOR: BL (TM) . . . . . . . . 14.08
VAS (LITERS) . . . . . . 76.7
SUSPENSION COMPLIANCE: CMS (µM/N) . . . . 177.00
FREE-AIR RESONANCE: FS (HZ) . . . . . . . . 28.00
MECHANICAL Q: QMS . . . . . . . . . . . 8.85
ELECTRICAL Q: QES . . . . . . . . . . . 0.57
TOTAL Q: QTS . . . . . . . . . . . . 0.54
MAXIMUM EXCURSION: XMAX (IN) . . . . . . . . 0.48
XMAX (MM) . . . . . . . 12.1
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Old 19th October 2018, 03:05 PM   #35
Circlomanen is offline Circlomanen  Sweden
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I would not recommend that driver. The JBL CS1214 has a too high Qts and Vas and a way too low Bl for this kind of enclosure. It can be done, but it will sound bland and resonant, lacking a well defined and hard punch.

I would use that driver in an OB or large closed box.
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Old 19th October 2018, 04:05 PM   #36
UPitt is offline UPitt
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Originally Posted by Circlomanen View Post
I would not recommend that driver. The JBL CS1214 has a too high Qts and Vas and a way too low Bl for this kind of enclosure. It can be done, but it will sound bland and resonant, lacking a well defined and hard punch.

I would use that driver in an OB or large closed box.
That makes sense because the simulations I've done with look awful without heavy DSP filters and even then the box issues should still be audible. I bought them anyways to load one into a closed box and the other into a folded horn but I'll still probably build this anyways because I have the two drivers and an excess of scrap wood that won't be good enough to use for other projects. If the design sounds decent enough with the DSP I will just give it to one of my friends in a fraternity because they could always use a "loud sound box" where quality doesn't really matter
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Old 19th October 2018, 04:13 PM   #37
Zwiller is offline Zwiller  United States
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Last time I was bargain hunting the Alpine S series simmed decent in similar designs. That said, I think Freddi nailed it with the Dayton.

No more questions! Give the man time to work on dual driver version!!!
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Old 30th October 2018, 09:57 AM   #38
wonderfulaudio is offline wonderfulaudio
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How is the port tuned? It looks like a big hole with no port length. It would be nice if one can explain how it works at two frequencies
a) At a frequency away from the Helmholtz's tuning frequency and
b) At the tuning frequency.

Thanks
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Old 30th October 2018, 05:41 PM   #39
Circlomanen is offline Circlomanen  Sweden
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endastHH.JPG

This is only the Helmholtz frontchamber simulated in Hornresp.

The Helmholtz frontchamber will act as high Q low pass filter, passing everything below its tuning frequency but adding its own resonant "gain" around the tuning frequency (upper part of the passband). The lower tuning frequency is from the tapped pipe that encircles and ends in the Helmholtz resonant chamber.

This simplified Hornresp simulation is not correct since the tapped pipe and the Helmholtz front chamber couples tightly to each other - which is not shown here.
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Old 30th October 2018, 05:52 PM   #40
Circlomanen is offline Circlomanen  Sweden
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HHTP.JPG

Both curved overlaid. This is not really the correct way to simulate since the tapped pipe and the Helmholtz frontchamber couple to and effect each other.

I made this simplified Hornresp simulation just to try to show the contribution of the two different parts in a more clear and distinguishable way.
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