The Couple Jack
The coupling jack allows you to couple two or more units gain reduction. A diode can be used to "reference couple" two or more units. This is useful to send a midrange reference control signal to a bass compressor in a multiband configuration or for sidechain subsonic enhancement or ducking purposes.
We now build new units standard with a six position recovery selector which allows the Sta-Level to go from the stock slow recovery to medium, fast and very fast in six steps. We also added a three position switch inside that captures three different classic tube compression flavors. Position One is the stock single time constant for attack. Position Two provides very musical dual time constants. Position Three is dual time constant with very fast attack like the famed Fairchild 660 and 670. Let's record!
You can check a new STA-LEVEL circuitry balance without test equipment. Listen to the output while holding the BAL. NULL button, adjust the BALANCE control for minimum 60 Hz. You have just balanced the gain of the push-pull circuitry! If the null is at the edge or end of the control range, you likely have a weak tube or bad component. It's easy to check whenever you like.
Custom 6386 Board
The 6386 Board uses a pair of 6AU6-family tubes. The choice of tubes has a significant effect on the sound of your compressor. We always hand-select a pair that performs closest to the original 6386.
We have several 6386 tubes around the shop. They are all unique. Some are noisy. Some are poorly matched. Many times they will not maintain match with varying bias (gain reduction). Fortunately if you have a 6386 that isn't matched well, they can still sound fine in the STA-LEVEL. A decent 6386 performs well in terms of noise and microphonics. If a STA-LEVEL sounds bad, the original coupling capacitors probably need to be replaced!
The 2C51/5670 is a tube that is pin compatible with a 6386. The transfer curve is radically different and will produce an undesirable compression ratio curve. The 2C51/5670 is also very microphonic in the STA-LEVEL application. Don't use it.
The Retro 6386 Board has a rectifier for the filaments, keeping this circuit hum-free when using the following tubes with varying characteristics. Here are most of the tubes that will work in the board. We only recommend a few of them for use in a STA-LEVEL. It's always best to use a matched pair. We check the bias curve, noise and microphonic performance. Many of these tubes were used in TV sets and radios and are plentiful.
6AU6, 6AK6, 6CG8, 6AH6, 6BA6, 6BH6, 6BJ6, 6CF6, 6265, 6136, 5749, 5725
We have these boards available for retrofitting many 6386-based units. Please contact us for information specific to your model.
Delivered with custom stereo link switch panelGain Reduction Threshold: Continuously adjustable from +24dBm to -20dBmAvailable Gain Reduction: 40dBTotal System Gain: 35dB (with standard input and output pads)Distortion: 1 percent or less from 0-30 dB gain reductionFrequency Response: Â± .25dB from 20-20,000 HzNoise: -70dB or better referenced to gain reduction thresholdOutput Level: Continuously adjustable from -40 dBm to +18 dBmInput Impedance: Accepts low impedance active or transformer balanced 0-600 OhmsOutput Impedance: 600 Ohm transformer balanced, terminated and resistive pad coupledTube Complement: 6386 (or 2-6BJ6), 1-12AT7, 2-6V6GT, 1-6AL5, 1-OB2, 1-5Y3Power Requirements: Three prong IEC 100-125 VAC, 50/60 Hz, 45 WattsMounting Requirements: 3U metal rack 5.25" high, 19" wide, 8" deep