Leslie Speakers - Revision history

ST: /* Bass Driver Modification */ formatting

2011-03-23T20:45:49Z

Bass Driver Modification: formatting

← Older revision		Revision as of 20:45, 23 March 2011
Line 109:		Line 109:
	The stock Leslie Bass Driver is a 15-inch O.E.M. speaker capable of handling about 50 watts. Supply it with 40 watts of a 30 Hz pedal tone and it shakes a lot. You may also be getting dangerously close to the driver<nowiki>’</nowiki>s excursion limit, but it seems to be pretty sturdy. I<nowiki>’</nowiki>ve certainly heard of them breaking with "stock" use. If only a keyboard is used through the system - one without a lot of deep bass - and you protect the driver by filtering out the low-end, the unit may handle lots more as you approach its "thermal limit". If you want to avoid running the risk of breaking the bass driver, the easiest solution is to replace it with another unit capable of handling higher loads. Speaker choice is left up to the individual; since it<nowiki>’</nowiki>s a matter of taste I can<nowiki>’</nowiki>t really recommend any. An 18-inch speaker will fit with the following modifications: a spacer ring has to be added between the speaker and the Leslie baffle (so that the cone doesn<nowiki>’</nowiki>t hit it), and part of the back panel may have to be whittled out for certain larger 18-inch speaker frames.		The stock Leslie Bass Driver is a 15-inch O.E.M. speaker capable of handling about 50 watts. Supply it with 40 watts of a 30 Hz pedal tone and it shakes a lot. You may also be getting dangerously close to the driver<nowiki>’</nowiki>s excursion limit, but it seems to be pretty sturdy. I<nowiki>’</nowiki>ve certainly heard of them breaking with "stock" use. If only a keyboard is used through the system - one without a lot of deep bass - and you protect the driver by filtering out the low-end, the unit may handle lots more as you approach its "thermal limit". If you want to avoid running the risk of breaking the bass driver, the easiest solution is to replace it with another unit capable of handling higher loads. Speaker choice is left up to the individual; since it<nowiki>’</nowiki>s a matter of taste I can<nowiki>’</nowiki>t really recommend any. An 18-inch speaker will fit with the following modifications: a spacer ring has to be added between the speaker and the Leslie baffle (so that the cone doesn<nowiki>’</nowiki>t hit it), and part of the back panel may have to be whittled out for certain larger 18-inch speaker frames.

	== Crossover Modification == The stock Leslie crossover is a 12 dB per octave, 800 Hz unit requiring both 16-ohm high- and low-frequency drivers for correct performance. Most "mondo-power" 15-inch woofers have an impedance of 8 ohms, which tends to extend the reponse a bit higher than 800 Hz. Although this shouldn<nowiki>’</nowiki>t cause any difficulties, it will make an 8-ohm high-frequency driver extend a bit lower, which will definitely cause excursion problems. The answer is to either buy a 16-ohm replacement driver, or perform the following modifications.		== Crossover Modification ==
			The stock Leslie crossover is a 12 dB per octave, 800 Hz unit requiring both 16-ohm high- and low-frequency drivers for correct performance. Most "mondo-power" 15-inch woofers have an impedance of 8 ohms, which tends to extend the reponse a bit higher than 800 Hz. Although this shouldn<nowiki>’</nowiki>t cause any difficulties, it will make an 8-ohm high-frequency driver extend a bit lower, which will definitely cause excursion problems. The answer is to either buy a 16-ohm replacement driver, or perform the following modifications.

	If the Leslie is fitted with both 8-ohm high- and low-frequency components, a stock 800 Hz crossover can be obtained from JBL, Altec, and other manufacturers. Community Light & Sound makes a very good crossover, which requires an 8-ohm bass speaker and a 16-ohm treble speaker (if you use it without its attenuation pad). The crossover handles well over 200 watts RMS, and is made from aircore coils and Mylar capacitors. Besides being a true "hi-fi" crossover, it would make an excellent choice for a super-power system. It is also possible to design and build your own crossover network from drawings and circuits published in any of the audio textbooks and cook books.		If the Leslie is fitted with both 8-ohm high- and low-frequency components, a stock 800 Hz crossover can be obtained from JBL, Altec, and other manufacturers. Community Light & Sound makes a very good crossover, which requires an 8-ohm bass speaker and a 16-ohm treble speaker (if you use it without its attenuation pad). The crossover handles well over 200 watts RMS, and is made from aircore coils and Mylar capacitors. Besides being a true "hi-fi" crossover, it would make an excellent choice for a super-power system. It is also possible to design and build your own crossover network from drawings and circuits published in any of the audio textbooks and cook books.
Line 125:		Line 126:
	[[Image:Leslie_Speakers_05.png\|framed\|none]]		[[Image:Leslie_Speakers_05.png\|framed\|none]]
	-->		-->

	== Tandem Rotors ==		== Tandem Rotors ==
	Slower acceleration of the lower rotor is occasionally undesirable - certainly, a matter of personal preference only. To give a more dramatic Leslie sound, the top and bottom rotors can be mechanically linked so that both will turn in sync, and the pair of horns face in the same direction. Silver Sound Systems (337 South Morris Avenue, Crum Lynn, Pennsylvania) built the little screamer with tandem rotors shown in Figure 11, which is an example of a well-prepared custom Leslie unit. It enhances the Leslie action by putting full range sound into the bass unit and only high frequencies to the treble unit. This customized unit was designed for use with electric guitars.		Slower acceleration of the lower rotor is occasionally undesirable - certainly, a matter of personal preference only. To give a more dramatic Leslie sound, the top and bottom rotors can be mechanically linked so that both will turn in sync, and the pair of horns face in the same direction. Silver Sound Systems (337 South Morris Avenue, Crum Lynn, Pennsylvania) built the little screamer with tandem rotors shown in Figure 11, which is an example of a well-prepared custom Leslie unit. It enhances the Leslie action by putting full range sound into the bass unit and only high frequencies to the treble unit. This customized unit was designed for use with electric guitars.

ST: in Clifford Henricksen

2008-12-24T15:39:50Z

in Clifford Henricksen

← Older revision		Revision as of 15:39, 24 December 2008
Line 1:		Line 1:
	{{Editorial		{{Editorial
	\|Author=[[User:Clifford Henricksen\|Clifford Henricksen]]		\|Author=[[User:Clifford Henricksen\|Clifford Henricksen]]
	}}		}}
	[[Image:Leslie_Speakers_06.png\|framed\|none]]		[[Image:Leslie_Speakers_06.png\|framed\|none]]

ST: Author=Clifford Henricksen

2008-12-24T15:39:05Z

Author=Clifford Henricksen

← Older revision		Revision as of 15:39, 24 December 2008
Line 1:		Line 1:
	{{~~editorial~~}}		{{Editorial
			\|Author=[[User:Clifford Henricksen\|Clifford Henricksen]]
			}}
	[[Image:Leslie_Speakers_06.png\|framed\|none]]		[[Image:Leslie_Speakers_06.png\|framed\|none]]

ST: Category:Instrument

2008-12-22T19:37:01Z

Category:Instrument

@@ Line 164: / Line 164: @@
 Acknowledgements<br>Thanks to Ralph Brownlowe, Robert Rankin and Ed Sciaky (WIOQ, Philadelphia) for some priceless and valuable information used in the compilation of this article.
 ----
 <references/>
-[[category:Instruments]]
+----

ST: Category:Clifford Henricksen

2008-12-22T19:17:15Z

Category:Clifford Henricksen

← Older revision		Revision as of 19:17, 22 December 2008
Line 168:		Line 168:

	[[category:Instruments]]		[[category:Instruments]]
			[[Category:Clifford Henricksen]]

ST: editorial

2007-06-27T05:08:40Z

editorial

← Older revision		Revision as of 05:08, 27 June 2007
Line 1:		Line 1:
			{{editorial}}
	[[Image:Leslie_Speakers_06.png\|framed\|none]]		[[Image:Leslie_Speakers_06.png\|framed\|none]]

Line 43:		Line 44:

	The horn<nowiki>’</nowiki>s so-called coverage angle is taken from polar response charts such as these; it is the included angle between -6dB points from the horn<nowiki>’</nowiki>s on-axis level. Figure 4 and 5 show such coverage angles, compiled from a series of third-octave polar response curves. Note how the beamwidth gets smaller and smaller without the deflector. This means that if the deflectors are removed the sound will be much hotter on-axis, but much softer off-axis. Therefore, the AM portion of the Leslie Sound will be much more severe and "choppy", as many a rock and roller will tell you. Many Leslies played in clubs are faced backwards, with the top and bottom rear panels and deflectors removed, because the sound "cuts" better; an effect that translates as, "You can hear it better over the guitar player".		The horn<nowiki>’</nowiki>s so-called coverage angle is taken from polar response charts such as these; it is the included angle between -6dB points from the horn<nowiki>’</nowiki>s on-axis level. Figure 4 and 5 show such coverage angles, compiled from a series of third-octave polar response curves. Note how the beamwidth gets smaller and smaller without the deflector. This means that if the deflectors are removed the sound will be much hotter on-axis, but much softer off-axis. Therefore, the AM portion of the Leslie Sound will be much more severe and "choppy", as many a rock and roller will tell you. Many Leslies played in clubs are faced backwards, with the top and bottom rear panels and deflectors removed, because the sound "cuts" better; an effect that translates as, "You can hear it better over the guitar player".
			<!--
	[[Image:Leslie_Speakers_01.png\|framed\|none]]		[[Image:Leslie_Speakers_01.png\|framed\|none]]
			-->
	This beaming process will actually raise the on-axis sensitivity of any driver, as can be seen from the frequency-response curves of a University ID-40 driver (a respectable, but typical 3/4-inch throat PA unit) mounted on a Leslie horn with and without deflectors (Figures 6 and 7). It is interesting to note the extra sensitivity above 1.5 kHz available without the reflectors in place. (Note also that the low-end - 800 Hz to 1.5 kHz - response isn<nowiki>’</nowiki>t affected by removing the reflector, and that the response is ± 5 dB from 400 Hz to 10 kHz. This latter range could be made even flatter with a real-time analyzer and an third-octave equalizer in the studio.)		This beaming process will actually raise the on-axis sensitivity of any driver, as can be seen from the frequency-response curves of a University ID-40 driver (a respectable, but typical 3/4-inch throat PA unit) mounted on a Leslie horn with and without deflectors (Figures 6 and 7). It is interesting to note the extra sensitivity above 1.5 kHz available without the reflectors in place. (Note also that the low-end - 800 Hz to 1.5 kHz - response isn<nowiki>’</nowiki>t affected by removing the reflector, and that the response is ± 5 dB from 400 Hz to 10 kHz. This latter range could be made even flatter with a real-time analyzer and an third-octave equalizer in the studio.)

ST: formatting

2007-06-26T21:12:47Z

formatting

Show changes

ST: prepared by Cliff Henricksen

2007-06-26T20:53:00Z

prepared by Cliff Henricksen

Show changes

ST: Musical Instruments moved to Leslie Speakers: For Cliff Henricksen

2006-11-04T19:32:24Z

Musical Instruments moved to Leslie Speakers: For Cliff Henricksen

← Older revision	Revision as of 19:32, 4 November 2006
(No difference)

ST: stub notice refined

2006-08-30T21:07:43Z

stub notice refined

← Older revision		Revision as of 21:07, 30 August 2006
Line 1:		Line 1:
	This is a stub awaiting input from people-at-Bose		This is a stub awaiting input from people-at-Bose

			Please DO NOT create Stub pages. If you want one please {{STPM}}.

			[[User:ST\|ST]] 04:07, 31 August 2006 (GMT-7)

	== Leslie Speakers ==		== Leslie Speakers ==