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Basshorn driver specs [message #17017] Sun, 03 October 2004 09:57 Go to next message
Kevin Jordan is currently offline  Kevin Jordan
Messages: 20
Registered: May 2009
Chancellor
On the subject of basshorns, there seems to be two schools of thought. The traditional
"old school" method is to use large, stiff, high fs, low xmax woofers. The reasons
stated for this choice are that the horn makes the bass and excursion isn't required because
the horn transforms high pressure low excursion at the cone into low pressure high volume
at the mouth. Then there is a new school of though that uses small, compliant, low fs,
high xmax woofers. The reasons stated for this choice are that even though excursion is
reduced, the deepest bass requires excursion anyway, more than is possible with the
old school stiff drivers. They say the use of high fs, low xmax drivers is largely due to
folklore and should be avoided. With drivers like the LAB12 (fs=22, xmax=13mm)
and the HL10 (fs=32, xmax=11mm), it would seem the common trend is towards
low fs, high xmax drivers for basshorns, just like for other bass speaker designs.
What are your thoughts here?
Rgs,
Kevin

Re: Basshorn driver specs [message #17018 is a reply to message #17017] Sun, 03 October 2004 18:36 Go to previous messageGo to next message
Mike.e is currently offline  Mike.e
Messages: 471
Registered: May 2009
Illuminati (1st Degree)
Hi Kevin

Your right there is new and old school.

Xmax is easier to get these days- and smaller drivers can be used.

My opinion-use the best driver for the task!

A linear 12" of lab12 specs will perform very well on a horn of limited bandwidth and high efficiency.

ML util program asks for this driver with given 30hz horn!
Hornresp models it up well!

The high BL drivers do the high end more effectively but require a long horn to achieve the same lows as the lower Bl drivers like lab12

All that remains is -is there any sound difference between these 2 drivers? i would say in theory no.

high/low Qms,BL,Moving mass, some say you can hear a difference,i dont see any AES articles on it..

with a lab12 driver you can have a small rear chamber which provides some linearity to prevent relying on the driver spider linearity alone!

Also reactance annulling can happen.

Cheers!
Mike.e


Re: Basshorn driver specs [message #17020 is a reply to message #17018] Mon, 04 October 2004 06:36 Go to previous messageGo to next message
Bill Fitzmaurice is currently offline  Bill Fitzmaurice
Messages: 335
Registered: May 2009
Grand Master
The 'old school' didn't do what they did because they wanted to, it was because they had to. Designers of those grand old horns of the RCA/Altec/Western Electric era used 15s in everything because they were the only drivers with enough displacement to deliver adequate power for the intended usage, which was primarily movie theatres. I'm sure that Harry Olsen would have used eights and tens if any had existed suitable for the purpose.

Re: Basshorn driver specs [message #17022 is a reply to message #17020] Mon, 04 October 2004 10:23 Go to previous messageGo to next message
Kevin Jordan is currently offline  Kevin Jordan
Messages: 20
Registered: May 2009
Chancellor
So you would rather use a small driver with high excursion to a large driver with low excursion?
Mechanical limits are mostly important at low frequency, right?
You like long throw woofers with low fs?
Rgs,
Kevin

Re: Basshorn driver specs [message #17024 is a reply to message #17020] Mon, 04 October 2004 10:49 Go to previous messageGo to next message
Kevin Jordan is currently offline  Kevin Jordan
Messages: 20
Registered: May 2009
Chancellor
Something is bothering me. Your statement implies that RCA, Altec and Western Electric were
somehow limited to the drivers of the day, but they *designed* the drivers of the day. They could
have made 10" drivers with the same linear travel as the 15's they built, but they chose not to.
Care to speculate why that was?
Rgs, Kevin

Re: Basshorn driver specs [message #17029 is a reply to message #17022] Mon, 04 October 2004 11:30 Go to previous messageGo to next message
Julenk is currently offline  Julenk
Messages: 4
Registered: May 2009
Esquire
Xmax limits bottm bass, power limits everthing above.
The voice coil melts from heat in the mids.
It hits the pole piece or rips the spider from overeaching the bass.

Re: Basshorn driver specs [message #17030 is a reply to message #17024] Mon, 04 October 2004 11:49 Go to previous messageGo to next message
Julenk is currently offline  Julenk
Messages: 4
Registered: May 2009
Esquire
No brainer. If ur power is limted, heat and xmax aint no big deal.
Swept volume is king and if u aint got xmax, u gotta have surface area.
Dat simpl.

--I dont disagree -nt-- [message #17031 is a reply to message #17020] Mon, 04 October 2004 20:20 Go to previous messageGo to next message
Mike.e is currently offline  Mike.e
Messages: 471
Registered: May 2009
Illuminati (1st Degree)
nt

Re: Basshorn driver specs [message #17038 is a reply to message #17024] Tue, 05 October 2004 07:14 Go to previous messageGo to next message
Bill Fitzmaurice is currently offline  Bill Fitzmaurice
Messages: 335
Registered: May 2009
Grand Master
I'm not so sure that they 'chose' not to; the first permanent magnet drivers appeared on the scene in the mid 1920s; the Altec A7 dates from only twenty odd years later. It's kind of like asking why Boeing didn't come out with the 747 in 1949.

Re: Basshorn driver specs [message #17041 is a reply to message #17038] Tue, 05 October 2004 09:26 Go to previous messageGo to previous message
Kevin Jordan is currently offline  Kevin Jordan
Messages: 20
Registered: May 2009
Chancellor
You missed my point, so let me rephrase it. If RCA, Altec and WE wanted 10" or 12" drivers
instead of 15", it would have been easy for them to make. They *chose* to use larger speakers.
I think they weren't worried about small size since they were designed for theaters.
Rgs,
Kevin

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