Manuals+

W2IHY 8 BAND AUDIO EQUALIZER AND NOISE GATE

OPERATING MANUAL

Introduction

Analog and digital technology have for many years been used in the audio industry to do audio equalization and noise reduction. Many amateurs have purchased audio equalizers and other equipment with the hope of improving their transmitted audio signal. The amateurs who have succeeded have in many cases had to pay premium prices for audio equipment that not only required modifying, to properly interface with their amateur stations, but also had to be hardened to tolerate R.F.

The W2IHY 8 Band Audio Equalizer and Noise Gate solves two basic problems many hams experience. The Audio Equalizer allows the user to change the transmitted audio frequency response without changing microphones or microphone cartridges. Transmitted audio, with substantial high frequency content, can be used to work DX or communicate in band conditions where there is a significant amount of noise. A balanced frequency response may be more desirable in strong signal, full noise quieting environments. Many amateur operators transmit audio in high ambient noise environments. Typical high noise sources include linear amplifier fans, dehumidifiers, room air conditioners, road and wind noise during mobile operation, etc..

The Noise Gate eliminates the aforementioned noise from being transmitted. On the air tests in high ambient noise conditions have shown the Noise Gate to be very effective. The removal of moderate to very high levels of ambient noise, from the transmitted audio signal, results in audio with increased clarity and presence.

Extensive testing was done of the Noise Gate and Equalizer. The unit has been designed to work in high RF environments. W2IHY offers a 30 day money back, no questions asked, guarantee. The W2IHY Audio Equalizer and Noise Gate represents affordable audio technology designed for amateur radio use.

Front Panel Controls

1. Power On/Off Switch (S1) / Phones (monitor) Volume Control (R29): This switch and potentiometer (Pot.) turns the unit's power on and off and is also used to adjust the audio level into the Phone jack.

2. Power on LED (LED3): This LED goes on when power is on in the unit.

3. Equalizer On/Off Switch (S3): This switch turns the equalizer on and off. When the equalizer is off, adjusting the equalizer's controls has no effect on the output audio.

4. Equalizer Controls (R11-R18): These slide potentiometers work only when the Equalizer On/Off Switch S3 is in the on position. The potentiometers control the output of 8 bandpass filters. The center frequencies of these filters are 50 Hz, 100 Hz, 200 Hz, 400 Hz, 800 Hz, 1600 Hz, 2400 Hz and 3200 HZ. The scale, for setting these potentiometers, is calibrated between -16 db. to +16 dB. Pushing a potentiometer forward (up) will increase the output of the equalizer within the bandpass of the filter whose slide potentiometer is changed. Pushing a potentiometer backward (down) will decrease the output of the equalizer within the bandpass of the filter whose slide potentiometer is changed. Setting all 8 potentiometers at the zero marking will produce audio at about the same output level as when the Equalizer On/Off Switch S3 (3) is in the off position. Adjusting the equalizer 50 Hz, 100 Hz and 200 Hz slide pots affects the heaviness / weight of the audio. Adjusting the equalizer 400 Hz and 800 Hz slide pots affects the warmth of the audio. Adjusting the equalizer 1600 Hz, 2400 Hz and 3200 Hz slide pots affects the clarity and presence of the audio.

5. Noise Gate On / Off Switch (S2): This switch turns the noise gate on and off. When the noise gate is off, changing the gate delay or level controls has no effect on the audio. When the noise gate is off, audio is always being passed (gated) through the noise gate to the output.

6. Noise Gate LED (LED1): This LED is used to help properly adjust the noise gate level control and to indicate when audio is being sent (gated) to the output. The LED being on (green) indicates that audio is being gated through the unit to the output. The LED being off indicates that audio is not being passed (gated) through to the output. When the Noise Gate On / Off Switch (5) is in the off position, the noise gate LED is on.

7. Noise Gate Level (R19): This slide pot. works only when the noise gate is on. This pot. sets the level at which background noise will be not gated to the audio output. Pushing this control up will make the unit less sensitive to higher background ambient noise. Pushing this control down will make the unit more sensitive to background noise.

8. Noise Gate Delay (R20): This control adjusts the length of time audio will be gated to the output after the noise gate has automatically turned off (Noise gate LED off). Pushing the delay slide pot. up increases the delay (decay) time. Pushing the pot. down decreases the delay time.

9. Mic Gain LED (LED2): This LED is used to help adjust the MIC In Gain pot. When the LED goes on, this indicates that the EQ is being overdriven. This LED should never go on.

Rear Panel Controls

10. Mic Select (S4): This three position switch selects the ICOM, KENWOOD or YAESU microphone plugged into the 8 pin Mic Input J8.

11. Mic Input (J8): 8 Pin microphone male connector. Do not use this connector when Mic in J6 (13) or Mic In J9 (12) are being used.

12. MIC Input (J9): This 3 pin XLR female connector works independent of the mic select switch and may be used as another mic source. Do not use this connector when Mic In J6 or J8 is being used.

13. Mic Input (J6): This RCA female connector is used as an auxiliary microphone input. This connector works independent of the mic select switch and may be used for another audio source or microphone. This input is also low impedance. Do not use if mic is connected to J8 (11) or J9 (12).

14. PTT INPUT (J7): RCA female connector for auxiliary push to talk control. A foot switch or other control may be connected to this connector. Grounding the center jack of the connector grounds the push to talk line on the Mic Out.

15. MIC Out Select A/B (S4): This two position slide switch directs audio to the 5 Pin DIN Mic Out A (16) or the 5 Pin DIN Mic Out B (17).

16. Mic Output A (J5): 5 Pin female DIN connector that has noise gate / equalizer audio plus push to talk outputted. This connector is active only when the Mic Out Slide Switch S4 (15) is in the Mic Out Select A position.

17. Mic Output B (J4): 5 Pin female DIN connector that has noise gate / equalizer audio plus push to talk outputted. This connector is active only when the Mic Out Slide Switch S4 (15) is in the Mic Out select B position.

18. Phones (J3): 1/4" Stereo headphone connector used to monitor audio from the equalizer. The output level of this connector is controlled by phone volume control R29 (1). Headphones using other than 1/4“ stereo connectors may not operate properly when plugged into stereo phones connector J3. (An inline adapter should be used with headsets that do not use 1/4" stereo connectors. Stores like Radio Shack have audio plug adapters available.)

19. Power: 5 Pin Din connector. 7 - 14 VDC input at 100 ma.

Bottom Panel Controls

20. Mic Jumper: Plugging the jumper (shorting block) puts +5V on the Mic In line of the microphone's cartridge (11, 12 & 13). Required for mic's such as ICOM's Hm12, HM36 and Sm6 and the Heil Hmi and MH2 (made for the Elecraft radio's) and other electret microphones.

21. Mic In Gain (R12): This pot., when turned clockwise, increases the microphone amplifier's gain. The gain should be changed while speaking into microphone until Mic LED (10) just barely goes on. Now turn the pot counterclockwise, while speaking into the mic till the LED NEVER goes on. (The LED going on indicates that the EQ is being overdriven.) Microphone cartridges with very low output (Like a Heil HC4 or Heil HC5) may require the Mic In Gain Control to be adjusted to maximum gain.

22. Mic Output Level (R13): Changes the unit's audio output. (Clockwise rotation increases output.)

23. Mic Input Impedance: Insertion of one of these jumpers (shorting blocks) selects 200 or 600 ohm input impedance. No jumpers connected selects high impedance.

Mic Out & Power Cable Wiring

This section provides wiring diagrams for connecting the Equalizer/Noise Gate's Mic Out to various transceiver models.

DRAKE T4XB, COLLINS 32S 1, 32S3, COLLINS KWM2A: Use a 2 Pin Mic Connector Pin 1 for Mic Out, and connect the shield to Pin 2.

COLLINS 32V2, 32V3, KWS-1, Hallicrafters, E.F. Johnson: Use a 2 Pin Mic Connector Pin 2 for Mic Out, and connect the shield to the Spring/Case.

DRAKE TR7: Use a 4 Pin Mic Connector Pin 1 for Mic Out, Pin 2 for PTT, and Pin 3 for the shield.

TEN TEC: Use a 4 Pin Mic Connector Pin 1 for Mic Out, Pin 3 for PTT, and Pin 2 for the shield.

Kenwood TS520/TS530, TS820/TS830: Use a 4 Pin Mic Connector Pin 1 for Mic Out, Pin 2 for PTT, Pin 3 for the shield, and Pin 4 for Mic Out.

Note: DIN connectors shown are for soldering. Do not solder to the shield of the DIN connector.

Mic Out Wiring Options

5 PIN DIN MIC OUTPUT CONNECTION: Provides connections for + Mic Balanced, - Mic Balanced Output, Hi-Z Output, PTT, and Gnd.

Low Impedance Balanced Output to Low Impedance Radio: Uses a 5 Pin Male DIN connector with connections for + Mic Balanced, Mic Output, PTT, and Gnd (Mic cable shield).

Low Impedance Unbalanced Output to Low Impedance Radio: Uses a 5 Pin Male DIN connector with connections for + Mic, Unbalanced Output, PTT, and Gnd (Mic cable shield).

Low Impedance Unbalanced Output to High Impedance Radio: Uses a 5 Pin Male DIN connector with connections for + Mic, 1K Ohm, PTT, and Gnd (Mic cable shield).

High Impedance Unbalanced Output to High Impedance Radio: Uses a 5 Pin Male DIN connector with connections for HI-Z, PTT, and Gnd (Mic cable shield).

Important: DO NOT CONNECT MIC WIRE SHIELD TO SHIELD OF DIN CONNECTOR. CONNECT ONLY AS SHOWN.

Changing EQ Bandpass Filter Center Frequencies

Each EQ bandpass filter is very similar. The center frequencies, of each bandpass filter is determined by the values of the capacitors and resistors used. The equations below define what capacitor values are required for a given center frequency. Below is a schematic of a bandpass filter with a center frequency of 100 Hz.

The equations are valid for only the resistor values shown in the schematic. The bandpass filter in the schematic has a center frequency at 100 hz. Example: The capacitor values required to obtain a bandpass filter center frequency of 4800hz is calculated as follows:

C1 = 0.9046 / FREQ = 0.9046 / 4800 = 0.0001885 uF = 188.5 PF

C2 = C1 x 10 = 0.0018858 uF

The closest real value capacitors that can be purchased are as follows:

Getting Started Tutorial

Before plugging the power transformer into the wall, preset the following controls as indicated:

Adjusting the Mic Levels

While talking into the microphone, using a screwdriver, turn the Mic In Level Control (located at the bottom of the unit) clockwise until the Mic LED just goes on. Now turn the Mic in Level control counterclockwise such that the LED never goes on when you speak into the mic.

While talking into the microphone, using a screwdriver, turn the Mic Out Level control clockwise until the audio level, as shown by your transceiver's/transmitters metering is at the proper level. If you are using push to talk on your transceiver, you will have to push the PTT switch on your microphone while making this adjustment.

Noise Gate Adjustments

Turn the Noise Gate Switch on. (Please note that when the Noise Gate Switch is off, the Noise Gate LED should always go on indicating audio is being sent / gated to the Mic Out. When the Noise Gate Switch is turned on, the Noise Gate LED may be on or off depending on the position of the Noise Gate Level control and the Mic In audio level.) Adjust the Noise Gate Level control until the Noise Gate LED just goes off. This adjustment should be made with the level of ambient noise that will be present when you will be talking into the microphone. (If audio is coming from your transceiver's/ receiver's speaker, you should turn off the audio.) When you now talk into your microphone, the Noise Gate LED should go on indicating audio is being sent to the Mic Out. When you stop talking, the Mic Out LED should turn off indicating that audio is not being sent and background noise is not being sent / gated to the Mic Out.

Adjusting The Audio Equalizer

Turn the Equalizer Switch on. Set all 8 equalizer slide potentiometers to the 0 db point (marked on the case). Refer to the Preliminary Equalizer Setting table on page 20. Use this table as a guide to determine initial starting points for equalizer settings. It is suggested that the phones monitor be utilized to assist in adjusting the equalizer. As you modify your equalizer settings (to determine what the optimal setting is for you), it is recommended that you make changes starting at the highest audio frequency (3200 Hz) first and change the next lowest frequency (band) next until the lowest frequency (50 hz) is adjusted. On the air experimentation will be required to find the optimal settings based upon the user's voice characteristics and band conditions.

Preliminary Equalizer Settings

This table provides suggested equalizer settings for various microphones and radios.

Voice Qual Radio Setting 50 Hz. 100 Hz. 200 Hz. 400 Hz. 800 Hz. 1600 Hz. 2400 Hz. 3200 Hz.
EV 757B FT990 200 ohms DX +12 +8 +4 0 +4 +4 +8 +14
MD1 FT990 600 ohms DX +16 +12 +8 +4 +4 +8 +12 +16
Eletrovoice 660 FT1000D 600 ohms Rag Chew +12 +8 +4 0 0 +4 +12 +12
Eletrovoice 660 FT1000D 600 ohms DX +4 +4 +4 0 0 +4 +12 +12
Electrovoice RE27 FT1000D 200 ohms wide band +12 3- 3- -4 -4 3- 3- 0
Heil Goldline FT1000D 600 ohms wide band +12 0 0 +4 +8 0 0 +4 +8
D104 (100K ohms) FT1000D Hi-Z Rag Chew +12 +12 9+ 0 0 +4 +10 +10
D104 (100K ohms) FT1000D Hi-Z DX +4 +4 +4 0 0 +4 +10 +10
Heil HM-10 FT1000D 600 ohms Rag Chew +12 +12 9+ 0 0 0 +6 9+
Heil HM-10 FT1000D 600 ohms DX +4 +4 +4 0 0 0 +6 +6
Yaesu MH-1BB FT1000D 600 ohms Rag Chew +16 +16 +8 0 0 +4 +12 +12
Yaesu MH-1BB FT1000D 600 ohms DX +4 +4 +4 0 0 +4 +8 +8
Kenwood MC50 FT1000D 600 ohms Rag Chew +16 +16 +8 0 0 0 +4 +12 +12
Kenwood MC50 FT1000D 600 ohms DX +4 +4 +4 0 0 +4 +8 +8
ATM41a FT1000MP 600 ohms EDSP fil 300-3000 SSB Fil off (100-3100) Rag chew TxEDSP = 3, Txfil = 6.0 +12 +10 +8 +6 +4 +4 +8 +12
AKG C3000 FT1000MP 600 ohms SSB fil 100-3100, TLSB car = 50, Proc LSB +10, TUSB Car= -50, Proc USB=+10 Rag Chew +12 +12 +4 0 0 +8 +12 +12
AKG C5900 FT1000MP 600 ohms Rag Chew +4 -4 -4 +2 0 +8 +4
AKG C5900 Kachina 600 ohms Rag Chew +4 -4 -4 +2 0 +8 +4
Heil HC5 Kachina 600 ohms Rag Chew 0 +8 +4 +4 9+ +8
Heil Goldline Kachina 600 ohms Rag Chew 0 0 0 +4 +8 +8 +8 +12
Heil Goldline Kachina 600 ohms Rag Chew 0 +8 +4 +4 +8 +12 +14 +16
Electrovoice RE 20 TS870 200 ohms TX EQ on High Rag Chew +16 +2 0 0 0 +2 9+ +12
Menu 29 3000 Menu 30= 100 Gold Line Full Range TS870 600 ohms Menu 31= H rag Chev 0 +4 -16 -12 O 0 0
Menu 29 = 3000 Menu 30= 100 HC5 TS870 600 ohms Menu 31= B Rag Chew +12 +8 3- +3 b +2 +7
Lab Tech C-324 IC746 600 ohms Menue: TX Tone +12 Rag Chew +2 +2 +16 + +4 +10 +10
Lab Tech C-324 IC746 600 ohms Menue: TX Tone +12 DX -4 -4 0 +4 9+ +12 +12 +8
HM36 IC746 600 ohms Menue: TX Tone +12 Rag Chew 0 0 0 0 +4 +12 +12 +14
HM36 IC746 600 ohms Menue: TX Tone +12 DX +8 0 +4 +12 +12 +14 +8
Shure Dynamic 554SA IC746 HI-Z General +16 +4 +4 -6 +4 +3 -4
JRC NVT-56 TS870 HI-Z 3000 BW/100 Off Rag Chew +16 0 0 0 0 0 +4
Electrovoice 676 TenTec 705 OMNI V 600 ohms 2.8 Khz filters RAG Chew +16 +16 +16 +12 +4 +4 +4 +8

Internal Wiring

Diagrams illustrating the internal wiring of the unit are provided, showing component placement and connections.

PC Boards and Parts

Detailed layouts and parts lists for the Mother Board, 8 Band EQ Board, and Rear Connector Board are included.

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W2IHY 8 band audio equalizer user 2006

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