To whom it may concern,
I'm trying to biamp my new Leslie Speaker model 122A. My master plan
is to use the stock 40-watt amp to drive only the horn and a Mackie
SR1530 for the low-end duties. The Mackie is a solid-state tri-amped
system. In this scheme, I won't need the services of either the Mackie
mid or upper drivers. In other words I'll be using the Mackie amp to
power only its woofer, which now resides in the Leslie cabinet.

Here is the cut and paste spec sheet for the Mackie SR1530:

SR1530 Specifications
System:
Freq. Range (-10 dB)
40Hz - 20kHz
Freq. Response (-3dB)
45Hz - 18kHz
Horz. Coverage Angle (-6dB)
90°
Vert. Coverage Angle (-6dB)
40°
Directivity Factor; DI(Q)
10.77 (11.95) averaged 2kHz to 10kHz
Rated Maximum SPL (peak)
126dB @ 1m
Crossover Points
700Hz, 3,000Hz

Transducer:
Low-Frequency:
Diameter
15-inch (381mm)
Power Handling
300 watts Dynamic Program Power

Mid-Frequency:
Diameter
6-inch (152mm) diameter
Power Handling
100 watts Dynamic Program Power

High Frequency:
Exit Throat
1-inch (25.4mm)
Power handling
100 watts Dynamic Program Power

Amplifiers:
Low-Frequency Power Amplifier:
Rated Power
300 watts @ Low-Frequency Driver Impedance
Rated THD
0.05%
Cooling
Class AB Convection Extrusion

Mid-frequency amplifier:
Rated Power
100 watts @ Mid-Frequency Driver Impedance
Rated THD
0.01%
Cooling
Class AB Convection Extrusion

High-frequency amplifier:
Rated Power
100 watts @ High-Frequency Driver Impedance
Rated THD
0.01%
Cooling
Class AB Convection Extrusion





Being more musician than electrician results in the following
Shortcomings of knowledge;

Do I need a load of any kind where the mid and upper drivers were so
the Mackie amp doesn't suffer any ill effects from only being
connected to the woofer? (e.g. make amp run to hot, not at peak
efficiency, shorten its life, etc…)

If I need to have a dummy load where the mid and upper drivers were,
what is the best way to go about this. Just wire in the appropriate
resistor? If so what is the appropriate resistor?

The Leslie 122A is a 40 watt tube amp. I plan to put a load (16 ohm
10 watt resistor) on it where the original woofer was after the
crossover. Is that the best way to do it? The way I understand it
the woofer, driver and crossover all are 16ohm in the Leslie 122.

I would like to optimize the power going to the driver w/o alteration
of the driver's sound. Will running the amp into the crossover then
into the upper driver with a dummy load where the woofer was complete
the task? Or am I missing something here?
The driver is the new Leslie Ferro-fluid 100 watt driver.

I would be much obliged for any help I can get on this project.
Thanks.
Sincerely,
Trevor

(Trevor) wrote in message . com...
To whom it may concern,
I'm trying to biamp my new Leslie Speaker model 122A. My master plan
is to use the stock 40-watt amp to drive only the horn and a Mackie
SR1530 for the low-end duties. The Mackie is a solid-state tri-amped
system. In this scheme, I won't need the services of either the Mackie
mid or upper drivers. In other words I'll be using the Mackie amp to
power only its woofer, which now resides in the Leslie cabinet.

This newsgroup is mostly about home audio systems, so I don't think
you'll find much help here.

Two suggestions:

1. Search groups and web via Google.com to find places more relevant
for your query. I'm pretty sure there are newsgroups devoted to
musical audio gear.

2. An audio newsgroup that might provide technical info:
rec.audio.tech

3. When you find a good place to post your query, explain why you want
to modify the Leslie speaker and what you hope to achieve. Also
explain what you dislike like about the Leslie speaker and what you
want to improve.

Good hunting!

(snip)

I would like to optimize the power going to the driver w/o alteration
of the driver's sound.

In terms of sound, you need to do a better job of explaining what you
want to achieve by modifying the Leslie.

If you're already happy with the sound of the Leslie speaker, my
advice is that you don't modify it in any way. If you need greater
volume, maybe you could add a second Leslie speaker?

Anyway, good luck!

(snip)

Hi Neil,
Here is my cut and paste respone to another guy who suggested getting
another Leslie. Hopfully this will shed additional light on my
problem Thanks.
Trevor


I guess I want to biamp it because it's never loud enough on stage
once the drummer begins to play. I don't want the drummer to have to
play like a sissy because I can't come up to his level. Also, with
both a chopped Hammond A102 and a Leslie 122 cabinet to drag around
from gig to gig life is hard enough w/o adding a second Leslie to my
burden, not to mention the expense, $2000+ for the new ones. I'm not
like I was when I was 22 when I could just put a Leslie under each arm
and head up a flight of stairs (kidding.) Also, adding a second Leslie
doesn't give you that much more and certainly not enough to warrant
the trouble of adding it to the arsenal. Check out Clifford
Henricksen's page at
http://theatreorgans.com/hammond/faq...y/mystery.html for the 411
on that one.

I'm not playing with Neil Young and Crazy Horse, just small time
blues clubs. I though if I kept the tube amp driving the horns then
most of my crunch i.e. characteristic Leslie sound, would be
maintained. I've seen several Internet sites where this is the exact
approach they use as well: Drive the horn with the stock amp and the
lows with some solid-state amp with appropriate crossover. I thought
if I could rig my Leslie 122A up like this with what I already have
then I could reach my goal w/o to much compromise in sound and w/o a
huge cash outlay. I'm trying to make money as a musician not spend
it. Considering that I've already forked out $4500 for the Hammond
and Leslie it's kind of a shame that once the band starts playing I'm
lost in the mix with no headroom for solo's and it's not even a metal
band just classic rock and blues.
Yes, I've tried miking it but what a royal pain in the ass not to
mention the feedback problems that causes. When I mike it I can get it
loud enough through the mains but pulling it back up through the
monitors always causes problem and on stage is exactly where I need
the added dB's not out front.
I realize that some compromise would be made simply from the fact
that I'm introducing a solid-state amp into the mix. But overall I
think I would still have a better sounding Leslie than the new ones
simply from the fact that I was driving the horns with the tube amp.
If money were no object then I would just go out and buy the new
Motion Soun Pro-145 to the tune of $1800. But such is not the case.
You should know that the new Leslie 122's have a 100watt driver.
Trevor











(Neil) wrote in message . com...
(Trevor) wrote in message . com...
To whom it may concern,
I'm trying to biamp my new Leslie Speaker model 122A. My master plan
is to use the stock 40-watt amp to drive only the horn and a Mackie
SR1530 for the low-end duties. The Mackie is a solid-state tri-amped
system. In this scheme, I won't need the services of either the Mackie
mid or upper drivers. In other words I'll be using the Mackie amp to
power only its woofer, which now resides in the Leslie cabinet.

This newsgroup is mostly about home audio systems, so I don't think
you'll find much help here.

Two suggestions:

1. Search groups and web via Google.com to find places more relevant
for your query. I'm pretty sure there are newsgroups devoted to
musical audio gear.

2. An audio newsgroup that might provide technical info:
rec.audio.tech

3. When you find a good place to post your query, explain why you want
to modify the Leslie speaker and what you hope to achieve. Also
explain what you dislike like about the Leslie speaker and what you
want to improve.

Good hunting!

(snip)

I would like to optimize the power going to the driver w/o alteration
of the driver's sound.

In terms of sound, you need to do a better job of explaining what you
want to achieve by modifying the Leslie.

If you're already happy with the sound of the Leslie speaker, my
advice is that you don't modify it in any way. If you need greater
volume, maybe you could add a second Leslie speaker?

Anyway, good luck!

(snip)