High Efficiency Speaker Asylum

Need speakers that can rock with just one watt? You found da place.

Return to High Efficiency Speaker Asylum


Message Sort: Post Order or Asylum Reverse Threaded

8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?

45.233.66.30

Posted on December 24, 2020 at 15:51:56
Nicoro
Audiophile

Posts: 4
Joined: August 14, 2019
Returning to an old abandoned project of years ago.....a 1/2 wavelength 35 Hz horn sub. These would be for live sound. Ideally the driver should have maximal excursion with an Fs of around 45 to 50 Hz as the Fs would drop into the 30Hz range once in the horn. These Fs frequencies are usually for midbass drivers but these usually have limited Xmax. Subwoof drivers with Fs around 30Hz would drop the Fs to high teens in the horn and would have an inefficient power response in a 35Hz horn. Another possibility two six inch bass drivers with similar Sd (surface area) as an 8 inch with Fs in high 30s Xmax 7mm? As to the question of why a 1/2 wavelength horn as opposed to a 1/4 WL? A 1/2 wl horn will have 5dB more in output than the 1/4 WL. This is equivalent to carrying 3 to 4 one quarter WL horn sized cabs around and amps etc. Any suggestions appreciated

 

Hide full thread outline!
    ...
RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 24, 2020 at 19:32:26
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
I use the Dayton DCS 205-4 in a number of my folded horn subs. Fs is lower than needed, but that's easily compensated for with a small rear chamber. Eights with Fs higher than 35Hz and xmax longer than 5mm are rare.

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 25, 2020 at 23:19:51
Nicoro
Audiophile

Posts: 4
Joined: August 14, 2019
As per your suggestion a smaller rear chamber would be useful considering the lack of an ideal driver. Will keep that in mind and play with the numbers. The other thing is in sub freqs below 100 Hz most studies show that people can not detect distorsion of up to 10%. Will then likely push throat distortion up to maximize output in this live sound design.

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 26, 2020 at 06:19:44
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
For the most part you can't detect distortion below 100Hz. That's because distortion occurs in the harmonics, so 60Hz distortion, for instance, is heard at 120,180,240,300Hz etc. That doesn't mean you can ignore distortion in subs, though. because driven past xmax the driver itself creates those harmonics. Even below xmax long excursion will create Doppler distortion, as was well documented by Paul Klipsch. Getting the highest possible SPL from the shortest possible excursion is the reason why horn loaded subs have low distortion figures that direct radiators can't approach. Add in the low pass function of folded horns that filters out above pass band harmonics and one can understand why they give unrivaled results.

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 26, 2020 at 10:39:51
Nicoro
Audiophile

Posts: 4
Joined: August 14, 2019
"Getting the highest possible SPL from the shortest excursion" is easier said than done especially in Sub freqs. Horns help as do larger drivers but that defeats the purpose. The holy grail remains the highest Xmax and hopefully Doppler distortion will remain unnoticed in the sub freqs. Most patents trying to increase Xmax require a completely new speaker chassis redesign not very practical. A while back I came up with a design that using a traditional speaker chassis along with more than 1 magnetic gaps could provide much greater Xmax. But since power requirements rapidly go up as Xmax increases using multiple smaller drivers remained an alternative.

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 26, 2020 at 13:19:49
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
>"Getting the highest possible SPL from the shortest excursion" is easier said than done especially in Sub freqs

It's not all that difficult. My Table Tuba, loaded with an eight, will deliver 125dB at 28Hz with 80 watts input and 5mm excursion. Needless to say I seldom run it that hot. One watt is usually sufficient.

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 26, 2020 at 13:50:11
Bill,

have you ever experimented with 'auto' sub drivers, like those from Lanzar or Kicker etc.? some are very well constructed, with pretty high sensitivity and excursion. many have really impressive magnet / VC specs

regards,

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 26, 2020 at 14:01:49
Nicoro
Audiophile

Posts: 4
Joined: August 14, 2019
Bill your designs are great I been recommending them for many a year but as you can tell I like experimenting and pushing the bounderies. Will see what happens with this one. Thanks for the input

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 26, 2020 at 14:51:08
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
Most auto sound woofers have specs best suited to small sealed boxes, so Q is usually too high and EBP too low for good results in a horn.

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on December 26, 2020 at 14:54:00
ah ... thanks

regards,

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on January 5, 2021 at 06:13:17
morricab
Distributor or Rep

Posts: 9160
Location: switzerland
Joined: April 1, 2005
Supravox 215-2000 should work. Doesn't have a large Xmax but in the horn it shouldn't be moving visibly (in my TQWT setup you can't see them move even with large bass hits)

 

Supravox 215-2000, posted on January 5, 2021 at 08:20:40
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
The specs aren't suitable for a 35Hz horn, and the price is ten times what one needs to spend. The OP is building a sub woofer, not a full range speaker.

 

RE: Supravox 215-2000, posted on January 8, 2021 at 06:12:59
morricab
Distributor or Rep

Posts: 9160
Location: switzerland
Joined: April 1, 2005
All I can tell you is that in my room I am measuring flat to 30Hz in a TQWT cabinet. The length of the horn is around 2.1, 2.2 meters. It is not the same as an exponential horn as there is some mass loading at the mouth but I can tell you it works shockingly well.

 

RE: 8 inch driver recommendation for 1/2 wavelength 35 Hz horn subwoofer?, posted on January 24, 2021 at 13:24:42
EduardG
Audiophile

Posts: 284
Location: So. Cal
Joined: May 30, 2002
just out of curiosity - why an 8" driver for a 35Hz sub? I built a 35Hz sub using an 18" driver (EVM18B) and with 100 inch throat the wave was 10 feet long. With an 8" driver this would be a huge sub. Just wondering...

 

why an 8" driver for a 35Hz sub, posted on January 24, 2021 at 16:55:29
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
Why? Because that's all you need. A smaller driver allows a longer horn in a smaller box.

 

RE: why an 8" driver for a 35Hz sub, posted on January 24, 2021 at 17:59:25
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
Friend build a pair of speakers from the RADIO SHACK book probably 20 years or more ago.

8" woofer worked into a ported enclosure in which the port went to another enclosed space and THAT had an external port.

They'd go to 35 to 40 with ease.

Didn't sound half-bad, either. But a LOT of wood working than the crossover!

Riceball? If you're out there? Get in touch......
Too much is never enough

 

RE: why an 8" driver for a 35Hz sub, posted on January 24, 2021 at 20:16:22
EduardG
Audiophile

Posts: 284
Location: So. Cal
Joined: May 30, 2002
Yes, that's my point - MUCH longer horn...

 

RE: why an 8" driver for a 35Hz sub, posted on January 25, 2021 at 06:14:24
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
That's my point too. The low frequency corner of a horn is determined by its length. The longer the horn the lower it goes. A smaller driver allows a horn to go lower from a given overall box size. That's why I never use 18 inch drivers in horns, not even in pro-touring subs with 28Hz Fc.

 

Page processed in 0.024 seconds.