The ALH1 Adjustable Audio Hum Eliminator eliminates hum in computer and audio components

DCI Specialty ALH1

Adjustable Audio Hum Eliminator for
Stereo & Home Theater Systems

Frequently Asked Questions & Technical Info

What does the ALH1 Audio Hum Eliminator do?

What components can be used with the ALH1 Audio Hum Eliminator?

Why is the ALH1 Audio Hum Eliminator "Adjustable" and how do you adjust it?

How do you connect the ALH1 Audio Hum Eliminator?

How does the ALH1 Audio Hum Eliminator work?

What are the Specifications of the ALH1 Audio Hum Eliminator?

How does the ALH1 Audio Hum Eliminator compare with other products?

What does the ALH1 Audio Hum Eliminator do?
The ALH1 Audio Hum Eliminator eliminates hum in Stereo and Home Theater Systems. Components in different locations are most susceptible. Hum results from slightly different ground potentials at the power plugs. Long audio cables exasperate the problem. The ALH1 Hum Eliminator will cancel hum up to 2.5 volts- plenty of capability to handle common ground related hum up to several hundred feet in length in a building (typically up to 20mv). The ALH1 Hum Eliminator cannot correct for defective audio cables or defective AC power wiring or connectors. Also, performance is only assured with modern 3-prong grounded recepticle wiring.

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What components can be used with the ALH1 Audio Hum Eliminator?
You can use the ALH1 to connect TV Line outputs, Cable Box Line outputs, Computer Sound Card outputs, CD Players, Tape Players, Stereo or Home Theater Line outputs, and other sources to the Line Input of Stereos or Home Theaters or other amplifiers. The interconnect cables can be up to several hundred feet long.

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Why is the ALH1 Audio Hum Eliminator "Adjustable" and how do you adjust it?
Because all electrical wiring and audio installations are different, the DCI Specialty ALH1 Adjustable Audio Hum Eliminator has an adjustment for each channel to tune it to your specific installation. Simply turn the adjustment control for minimum hum.

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How do you connect the ALH1 Audio Hum Eliminator?

Connect the RCA audio plugs from your Line Level audio source to the ALH1 Hum Eliminator located at your amplifier. Connect the ALH1 Hum Eliminator to your amplifier with the RCA to RCA cable provided.

Since all audio cables and installations have different electrical characteristics, the ALH1 Hum Eliminator has independent controls for tuning each channel to your specific cable.

Simply turn the control until the Hum goes away. That's it!

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How does the ALH1 Audio Hum Eliminator work?
The ALH1 is an active electronic circuit which cancels hum by processing only the difference between the signal and the shield ground, effectively cancelling hum on the shield ground by injecting an opposite polarity hum signal. The signal remains true and unmodified, and has the same output level as the input. Independent controls are provided for tuning the circuit to the individual type and length of cable. The ALH1 Hum Eliminator is unlike an isolation transformer, which has insertion loss (drop in signal level), poorer frequency response, and greater distortion across the frequency band. Transformers can provide massive quantities of Common Mode Rejection at higher voltages, but that is rarely what is needed in a home audio system. Also, a quality transformer needs complicated winding and is therefore expensive. The ALH1 delivers highest performance audio quality.

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What are the Specifications of the ALH1 Audio Hum Eliminator?

Number of Signals:	2 (Stereo)
Adjustments:	Independent Right & Left Channel
Frequency Response:	DC to 100khz +/-0.2db
Distortion:	<0.01% DC to 100khz
Insertion Loss:	0db @ 1kz
Common Mode Rejection:	40db
Input Voltage Range:	+/-2.5 Vpp
Impedance:	10kohm (consumer-commercial)
Audio Connectors:	Gold Plated RCA
Size:	2-1/2" x 2-1/2" x 1-1/4"
Weight:	6oz.
Power:	U.L Approved 12VDC AC Adaptor Provided
Cable:	1-1' Gold Plated Stereo RCA to RCA Provided

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How does the ALH1 Audio Hum Eliminator compare with other products?
A comparison of other types. Data from their web sites as of 10/18/04:

Model:	DCI Specialty ALH1	Jenson CI-2RR	Radio Shack 270-0054
Type:	Stereo Electronic Circuit	Stereo Isolation Transformer	Stereo Isolation Transformer
Adjustable:	Yes- Independant Channels	No	No
Frequency Response:	DC to 100khz +/-0.2db	20 to 20khz -0.03db/-0.7db 0.25 to 50khz -3db	300-4,000hz +/-3db
Distortion:	<0.01% DC to 100khz	0.04% @ 20hz <0.001% @1khz	Not Stated
Insertion Loss:	0db @ 1khz	0.82db @ 1khz	Not Stated
Common Mode Rejection:	40db	95db @ 60hz 85db @ 3khz	Not Stated
Price:	$43.50	$177.95	$16.99

Comparison Summary:
The DCI Specialty ALH1 has significantly better flat frequency response across the entire audio band. It also has lower distortion, and higher output than both.

The Jenson unit exceeds the ALH1 only in CMR. However, the ALH1 does suppress hum 40db (1/100'th of its original level), which is WAY down there.

The Radio Shack unit has frequency response that is barely better than speech quality, and being a consumer grade transformer circuit, distortion and insertion loss are predictively high.

The DCI Specialty ALH1 provides professional grade audio performance at a reasonable price.

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DCI Technology, LLC 2004- Last Updated 12/1/07

DCI Specialty ALH1

Adjustable Audio Hum Eliminator for Stereo & Home Theater Systems

Adjustable Audio Hum Eliminator for
Stereo & Home Theater Systems