# What are they? - Rock concert equipment **URL:** \ **Category:** Factual Questions\ **Created:** [April 21, 2010, 4:47pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873 "2010-04-21T16:47:16Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![MikeF](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@MikeF](https://boards.straightdope.com/u/MikeF)\ **Post date:** [April 21, 2010, 4:47pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/1 "2010-04-21T16:47:16Z")
What are those things I’ve seen at rock concerts that sit on top of speakers or something on stage that spin around from time to time? They look like a pair of horns mounted horizontally opposite each other with the bell end facing out. They spin up to a pretty high speed, slow down and then stop. Is this producing some kind of sound effect or is something else going on? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [April 21, 2010, 4:51pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/2 "2010-04-21T16:51:06Z")
a Leslie speaker for treble range ---
**Author:** ![WordMan](https://avatars.discourse-cdn.com/v4/letter/w/e8c25b/32.png) [@WordMan](https://boards.straightdope.com/u/WordMan)\ **Post date:** [April 21, 2010, 4:53pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/3 "2010-04-21T16:53:54Z")
> [@johnpost](#): > > a Leslie speaker for treble range \*\*johnpost \*\*speaks truth - they are[Leslie speakers](http://en.wikipedia.org/wiki/Leslie_speaker) (wiki link). They rotate at high speed, creating a vibrato-like effect due to the Doppler effect of your ears processing the same sound from different locations while the speaker rotates. Infamously paired with a [Hammond B3 Organ](http://en.wikipedia.org/wiki/Hammond_b3) for rock, blues and jazz organ playing - the effect ads a touch of spice, helping the electic organ get a bit more of that air-blown sonority that a real pipe organ has. John Lennon famously sang through a Leslie which had been hacked to accept a vocal mic by engineer Geoff Emerick - for the last verse of Tomorrow Never Knows off Revolver… ---
**Author:** ![MPB\_in\_Salt\_Lake](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MPB\_in\_Salt\_Lake](https://boards.straightdope.com/u/MPB_in_Salt_Lake)\ **Post date:** [April 21, 2010, 4:54pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/4 "2010-04-21T16:54:39Z")
> [@MikeF](#): > > What are those things I’ve seen at rock concerts that sit on top of speakers or something on stage that spin around from time to time? They look like a pair of horns mounted horizontally opposite each other with the bell end facing out. They spin up to a pretty high speed, slow down and then stop. Is this producing some kind of sound effect or is something else going on? They are called Leslie (sp?) speakers, and are often used with Hammond B-3 organs… The sound that comes out of a B-3 with Leslie speakers is one of the warmest, most sublime sounds in all of the entire music world. (Art Neville, Brent Mydland, Gregg Allman) ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [April 21, 2010, 5:04pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/5 "2010-04-21T17:04:32Z")
> [@WordMan](#): > > John Lennon famously sang through a Leslie which had been hacked to accept a vocal mic by engineer Geoff Emerick - for the last verse of Tomorrow Never Knows off Revolver… Your wiki link gives a number of really good examples if someone’s unfamiliar with exactly what sound is being produced. The one that did it for me was Robert Plant in _No Quarter_. ---
**Author:** ![blondebear](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blondebear/32/1022_2.png) [@blondebear](https://boards.straightdope.com/u/blondebear)\ **Post date:** [April 21, 2010, 5:09pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/6 "2010-04-21T17:09:16Z")
Ken Hensley of Uriah Heep used these to great effect. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [April 21, 2010, 5:13pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/7 "2010-04-21T17:13:16Z")
> [@WordMan](#): > > John Lennon famously sang through a Leslie which had been hacked to accept a vocal mic by engineer Geoff Emerick - for the last verse of Tomorrow Never Knows off Revolver… Why would it have to be hacked? ---
**Author:** ![cjepson](https://avatars.discourse-cdn.com/v4/letter/c/a9adbd/32.png) [@cjepson](https://boards.straightdope.com/u/cjepson)\ **Post date:** [April 21, 2010, 5:18pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/8 "2010-04-21T17:18:16Z")
> [@CookingWithGas](#): > > Why would it have to be hacked? It was the speaker for a Hammond organ. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [April 21, 2010, 5:25pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/9 "2010-04-21T17:25:53Z")
> [@blondebear](#): > > Ken Hensley of Uriah Heep used these to great effect. On “Rainbow Demon”, perhaps? Steppenwolf’s “Hodge, Podge, Strained Through A Leslie” is, perhaps not surprisingly, also a nice example of the sound. ---
**Author:** ![WordMan](https://avatars.discourse-cdn.com/v4/letter/w/e8c25b/32.png) [@WordMan](https://boards.straightdope.com/u/WordMan)\ **Post date:** [April 21, 2010, 5:42pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/10 "2010-04-21T17:42:38Z")
> [@CookingWithGas](#): > > Why would it have to be hacked? Great excuse to plug Emerick’s book, [Here, There and Everywhere](http://www.amazon.com/Here-There-Everywhere-Recording-Beatles/dp/1592401791) (Amazon link) - wonderful inside look at making Beatles’ records… \*\*cjepson \*\*is correct - basically the connectors and circuits for musical instruments have a different set of standards vs. microphones, so this instrument speaker needed to be re-config’d to work in a microphone rig… ---
**Author:** ![blondebear](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blondebear/32/1022_2.png) [@blondebear](https://boards.straightdope.com/u/blondebear)\ **Post date:** [April 21, 2010, 5:52pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/11 "2010-04-21T17:52:12Z")
> [@Squink](#): > > On “Rainbow Demon”, perhaps? I was thinking of _Easy Livin’_, actually. I think it’s safe to say that the Hammond/Leslie sound is integral to Heep’s music. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [April 21, 2010, 8:33pm UTC](https://boards.straightdope.com/t/what-are-they-rock-concert-equipment/536873/12 "2010-04-21T20:33:31Z")
> [@cjepson](#): > > It was the speaker for a Hammond organ. I’ve plugged guitars into them, don’t they just have a hi-Z 1/4" phone plug for input? I guess if a lo-Z mike were used you’d have to use an adapter or something.