Taming an amplified signal/bypassing an amp??

manthe · 28th February 2008, 05:46 PM

This might sound strange, but it stems from relative ignorance...

I have recently acquired a Leslie amp. It is a 330 that has been upgraded to a 900 amp. Basically there is a 2-channel 'preamp' box with volume controls and foot switches for on/off and speed.

Here's the deal...

For direct guitar, this is fine, for the most part. It is a solid state amp and, aside from a potential issue with the horn, it sounds pretty good.

My Hammond organ, on the other hand, has been modified with a 1/4" output that carries an amplified signal (from the built-in tube amp). It is obviously meant to drive a speaker cab/'passive' Leslie.

My question is this:

If I turn the amp on the organ all the way down AND use the attenuation switch, is it OK to use that signal into the Leslie's preamp? If not (apart from a complete mod), is there a device I can put between the organ and the Leslie (or any other amp, for that matter) to somehow 'tame' that signal?

Also, does any one here have any experience with that particular Leslie model? Would it be feasible to modify the Leslie so that 1 channel is actually UN-amplified? In other words, I'd like to have 1 of the 1/4" inputs on the Leslie act like it is just a passive Leslie speaker cab.

ONE LAST QUESTION - Sorry - Re: the amped signal coming from my organ - will this damage a stomp box?

THANKS!

Antonio_4346 · 20th August 2008, 09:50 AM

Did you ever get an answer to this? I have a similar situation and an answer to yours may very well help my own.

squeegybug · 20th August 2008, 02:48 PM

You can send speaker-level output to another amplifier's input, but you need to reduce the voltage to get it back to line level first. One way is as mentioned, just lower the volume of the output amp. But that can often be noisy in my experience, and you run the risk of the volume being turned up accidentally and overloading the 2nd amp.

There are passive impedance-matching devices that do this, such as the discontinued Carver Z-5. I have a couple of these that I have used often, they work great and include builtin individual attenuators. It actually has 5 channels, was designed to fit between Carver's old HT products.

There are other similar devices for $40-60 that are used in car stereo applications, to connect a head unit to a separate outboard power amp. Most of those I have used can be very noisy.

Or, you can search for 'voltage divider' and easily make your own network with a couple of resistors. This is basically how many subwoofer speaker level inputs are made. Depending on your amp's power output, here is one that should work ok:

Speaker Level to Line Level

Steve

Fishmed · 20th August 2008, 03:48 PM

Behringer Ultra-G GI100 DI

Just don't use the Speaker Sim Button.

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28th February 2008, 05:46 PM	#1
manthe Lives for gear Join Date: Jan 2006 Location: Florida Posts: 1,751	Taming an amplified signal/bypassing an amp?? This might sound strange, but it stems from relative ignorance... I have recently acquired a Leslie amp. It is a 330 that has been upgraded to a 900 amp. Basically there is a 2-channel 'preamp' box with volume controls and foot switches for on/off and speed. Here's the deal... For direct guitar, this is fine, for the most part. It is a solid state amp and, aside from a potential issue with the horn, it sounds pretty good. My Hammond organ, on the other hand, has been modified with a 1/4" output that carries an amplified signal (from the built-in tube amp). It is obviously meant to drive a speaker cab/'passive' Leslie. My question is this: If I turn the amp on the organ all the way down AND use the attenuation switch, is it OK to use that signal into the Leslie's preamp? If not (apart from a complete mod), is there a device I can put between the organ and the Leslie (or any other amp, for that matter) to somehow 'tame' that signal? Also, does any one here have any experience with that particular Leslie model? Would it be feasible to modify the Leslie so that 1 channel is actually UN-amplified? In other words, I'd like to have 1 of the 1/4" inputs on the Leslie act like it is just a passive Leslie speaker cab. ONE LAST QUESTION - Sorry - Re: the amped signal coming from my organ - will this damage a stomp box? THANKS! __________________ -Mike Manthe Moonface, LLC ------------------------- Moonface Records \| Studio \| Publishing \| My Web Site \| \| My Equipment List \|

20th August 2008, 03:48 PM	#4
Fishmed Gear addict Join Date: Jun 2007 Location: Alabama Posts: 408	Behringer Ultra-G GI100 DI Just don't use the Speaker Sim Button. __________________ -Fishmed

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20th August 2008, 09:50 AM	#2
Antonio_4346 Gear interested Join Date: Aug 2008 Location: Denver, CO Posts: 23	Did you ever get an answer to this? I have a similar situation and an answer to yours may very well help my own.

20th August 2008, 02:48 PM	#3
squeegybug Lives for gear Join Date: Feb 2004 Location: Missouri USA Posts: 2,012	You can send speaker-level output to another amplifier's input, but you need to reduce the voltage to get it back to line level first. One way is as mentioned, just lower the volume of the output amp. But that can often be noisy in my experience, and you run the risk of the volume being turned up accidentally and overloading the 2nd amp. There are passive impedance-matching devices that do this, such as the discontinued Carver Z-5. I have a couple of these that I have used often, they work great and include builtin individual attenuators. It actually has 5 channels, was designed to fit between Carver's old HT products. There are other similar devices for $40-60 that are used in car stereo applications, to connect a head unit to a separate outboard power amp. Most of those I have used can be very noisy. Or, you can search for 'voltage divider' and easily make your own network with a couple of resistors. This is basically how many subwoofer speaker level inputs are made. Depending on your amp's power output, here is one that should work ok: Speaker Level to Line Level Steve