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18" speaker in a Leslie 122?


Gods element

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http://theatreorgans.com/hammond/dutchhammondsite/pictures/models/Leslie_122_RV_-_back.jpg

 

I'm guessing, but I would think that the size and mass of the 18" woofer would slow it (transients) down. I'm not exactly sure how the sound would change, but I feel certain that it would.

 

It's a two-way system, right? The tweeter is handling a lot of the midrange and so is the woofer. If you (could) put a larger woofer in the cabinet that was tuned and spec'd to sound good with a 15" woofer, you may end up not getting the results you expected - namely less midrange since you're using a bigger speaker.

 

I don't know if the 18" woofer would extend the low frequency response much since the cabinet hasn't been tuned for it, plus the rotor may not (efficiently) handle frequencies that low. I dunno. :rolleyes:

 

Is there a chance that you could borrow a 18" woofer and try it? If you could, I think it would be worth the experience to hear it for yourself.

 

Good luck.

 

Tom

"Music expresses that which cannot be put into words and that which cannot remain silent." - Victor Hugo
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I have read of people putting 18"ers in their leslies but i never personally witnessed the sound. I think the eminence MAGNUM PRO-18HO would do just fine but i may have to get a 500watt amp for that.(can you imagine the wopper lowers that would have?) I am going to try to get pics of my Leslie amp mod on here soon so you can see what i have. I have an amp like this on the back of my Leslie. http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-794

 

 

http://editweb.iglou.com/eminence/eminence/pages/products02/speakpro/mag18ho.htm

A-102/Leslie 122...can't live without it.
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A substantial amount of speaker mass would not be covered by the baffle. So you would get a lot of low frequencies to which the doppler effect was not being applied. I would think this would delete the low end rotor effect rather than enhabce it. A 15'' is pretty tight in there to begin with. Is there even room to go up to an 18''?

Additionally. I have 15''s in my subs and they are thunderous. Why the need for an 18?

Steve

A Lifetime of Peace, Love and Protest Music

www.rock-xtreme.com

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I just have this need to step on the pedals and feel the earth shake. Don't get me wrong, my Leslie rattles windows now, and I am very pleased with the Evm 15B, but i just wanted to know if anyone on these fourms has personly heard an 18" in a Leslie. I actually prefer my vintage SRO 15" in the Leslie but it's getting a recone ATM.
A-102/Leslie 122...can't live without it.
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I've heard a few people say they like their vintage woofers better. The last time I had a real leslie I wound up replacing the woofer since it would distort at high volumes. Not the nice growly warm distortion, but rather a horrid overdriven speaker fuzz. The JBL I replaced it with gave a much warmer sound and held up better when driven at high volumes. Might have just been that the original speaker had run its course. But even back in the 70s I replaced the stock speakers with JBLs in my 122s and loved the results.

Steve

A Lifetime of Peace, Love and Protest Music

www.rock-xtreme.com

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Remember, the crossover on a Leslie is 800hz. How much of the actual signal is therefore enhanced by a larger woofer? More of the significant overtones that make a Hammond special are probably at the high end of the frequency spectrum. If you are concerned about low frequency distribution, make sure you don't have your Leslie up on wheels. It makes about a 6db difference if you are not on the floor directly with the cabinet (even on the little metal feet).

 

Al Goff (from GoffProf) has tried enhancing the tweeter sides of things to the point that a percussive note would force the horn assembly up into the top of the cabinet! Since the horn is free-floating, the volume of air moved by more sound pressure (due to increased wattage) could not fit thru the hole all at one time (about 1" driver goes into a 1/4" hole in the horn assembly).

 

Bottom line: mic the Leslie and eq top and bottom mics per your taste.

 

Brian.

Hammond T-582A, Casio WK6600, Behringer D
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I don't recommend shoehorning an 18" speaker in a 122. You can't enlarge the 15" cutout because the frame for the rotor fits only that size. And if the excursion of the 18" impacts the edge of the 15" cutout, the cone will rip itself to shreds.

 

Plus you'd need an 18" speaker with a 16 ohm impedance, good luck finding one.

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Back when I worked regularly with a B3, I always owned an extra speaker since the 15" EV SRO would only last about one year before the cone would start flapping. It had a lifetime warranty and I sent it back several times to EV for reconing. (Is the SRO series from EV still being made?)

 

If you could fit an 18" speaker in a Leslie, you'd have to enlarge the opening ... or what would the point be, right? I remember from that time (1970's) that EV also made a 30" woofer.

No guitarists were harmed during the making of this message.

 

In general, harmonic complexity is inversely proportional to the ratio between chording and non-chording instruments.

 

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EV Stopped making the SRO in the early 70's when they came out with the EVM series. I think the EVM 15L is very simular to the original SRO. Many believe the SRO is the best sounding 15" ever made which I agree. The harmonics are outstanding. The cone takes a beating because of it though, but I do all the repairs myself so i dont mind reconing every so often. From what i have read, there needs to be spacers to elivate the 18" woofer off the baffle to compensate for the Xmax of the speaker. As Hammondel AV explained in his post above, the right speaker with the the right fequences has to be used to preseve the Hammond sound. Not any Subwoofer can be used. The max fqs. should go up to at least 5khz before rolloff, that way all the hammonics of the mid range can be heard. Now about that 30" woofer :)
A-102/Leslie 122...can't live without it.
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Hey, you sound like a traditional organist, not a rock organist! Traditional organist like to hear the rafters and walls of the building vibrate to the 16' or 32' stops of pipe organs. 18" woofers I think are common in 'pipe' organ systems to be able to reproduce that foot length. Some of the Hammond tone cabinets had to be re-engineered to reproduce the lower tones because the RT series that had a special pedal tone generator that had 32' stops.

 

Unfortunately, the Hammond series that we are used to doesn't produce the best pedal bass sounds anyway! The original model A has sinewave bass versus the later complex tonewheel bass. The Leslie 21H/31H probably produces the best bass tones in conjuction with sinewave bass or add-on pedal bass options from various vendors (like Trek II). Part of the reason was the use of field coil speakers (only thing available at the time cheaply!) versus PM speakers, which are treasured by audiophiles today because of bass response.

 

Brian

Hammond T-582A, Casio WK6600, Behringer D
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Just another thing to consider:

A woofer needs an enclosure with a certain amount of internal volume to give optimum results. I'm not exactly sure, and someone else might comment about this, but I believe that an 18" speaker would need more space than what's available in the middle section of a Leslie 122. Here's a little chart that I found: (I don't know what it's worth)

FIGURE 1 - Box Volumes for Common Driver Sizes

Driver Diameter (in) Enclosure Volume (ft^3)

6 --------------------- 0.3 - 0.4

8 --------------------- 0.6 - 0.8

10 -------------------- 1.0 - 1.5

12 -------------------- 2.0 - 3.0

15 -------------------- 5.0 - 9.0

 

The chart stops there, but I figure that an 18" would want something like 10 cubic feet at least, while a Leslie 122 has about 6,38 cubic feet (woofer section only)...

 

martin

"Show me all the blueprints. I'm serious now, show me all the blueprints."

My homemade instruments

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