rlaury
Well-known member
Hi group:
I thought I might offer these to the group before adding them on my web site.
In racking up all types of modules that don't have there own 20dB Pad, Phantom on/off, and phase switch, we're faced with the problem of adding these features. The most common way of adding theses features is to route the signals up to the front panel through toggle switches, and then back to the XLR in's and outs. This is labor intensive due to the care required in routing the in's and out's and handling of the shields. The switch required for the Pad must be of very high quality designed to handle uA currents at Millivolt levels. (regular miniture 2 amp toggle switches ADD DISTORTION!) and are unreliable. The best way is to use relays located directly at the I/O's to do the job. This also has it's challanges in that most low level qualified relays require PCB mount and have no way to neatly chassis mount. In new designs that include designing a PCB for a pre-amp we can add these features to the PCB. But this solution has it's problems too with switching relays within a high gain can cause pops reguardless of
how much snubber circuitry you add.
Several years ago after racking up 4 Collins mic-pre's and 6 RCA pre's for a client in one sitting, I decided I might could make some money doing these custom jobs if I didn't have to spend all my time doing this repetitive and time consuming wiring. I decided to solve this problem by developing the XLR interface PCB's. The XLR female has a relay switchable pad using a high quality AROMAT SX relay with a guarnteed minimum switching level of 10uA @ 1 Mv signal. It also uses Vishay, ultra low noise RN55 1% resistors for the 20Db pad, and RN60 6.8K 1% resistors for the phantom feed. The XLR connector is the NEUTRIK D type, 2 part PCB connector. This allows you to mount the metal shell to the outside of your chassis and then attach the connector and PCB assembly from the rear as one unit. A small screw driver slot locks them together.
The XLR Male connector uses the same mounting technique and flips the phase when the relay is activated.
Both PCB's have the snubber circuits. The phantom feed point is bypassed with 2ea .22uF 100V film caps.
The relays are 12VDC but I can offer 5V, 12V, and 24V also. The pad is 20 dB +/- 1 Db designed for 150 ohm microphones feeding a 1500 ohm typical input.
If these can be of use to you guy's, email me at:
[email protected].
I thought I might offer these to the group before adding them on my web site.
In racking up all types of modules that don't have there own 20dB Pad, Phantom on/off, and phase switch, we're faced with the problem of adding these features. The most common way of adding theses features is to route the signals up to the front panel through toggle switches, and then back to the XLR in's and outs. This is labor intensive due to the care required in routing the in's and out's and handling of the shields. The switch required for the Pad must be of very high quality designed to handle uA currents at Millivolt levels. (regular miniture 2 amp toggle switches ADD DISTORTION!) and are unreliable. The best way is to use relays located directly at the I/O's to do the job. This also has it's challanges in that most low level qualified relays require PCB mount and have no way to neatly chassis mount. In new designs that include designing a PCB for a pre-amp we can add these features to the PCB. But this solution has it's problems too with switching relays within a high gain can cause pops reguardless of
how much snubber circuitry you add.
Several years ago after racking up 4 Collins mic-pre's and 6 RCA pre's for a client in one sitting, I decided I might could make some money doing these custom jobs if I didn't have to spend all my time doing this repetitive and time consuming wiring. I decided to solve this problem by developing the XLR interface PCB's. The XLR female has a relay switchable pad using a high quality AROMAT SX relay with a guarnteed minimum switching level of 10uA @ 1 Mv signal. It also uses Vishay, ultra low noise RN55 1% resistors for the 20Db pad, and RN60 6.8K 1% resistors for the phantom feed. The XLR connector is the NEUTRIK D type, 2 part PCB connector. This allows you to mount the metal shell to the outside of your chassis and then attach the connector and PCB assembly from the rear as one unit. A small screw driver slot locks them together.
The XLR Male connector uses the same mounting technique and flips the phase when the relay is activated.
Both PCB's have the snubber circuits. The phantom feed point is bypassed with 2ea .22uF 100V film caps.
The relays are 12VDC but I can offer 5V, 12V, and 24V also. The pad is 20 dB +/- 1 Db designed for 150 ohm microphones feeding a 1500 ohm typical input.
If these can be of use to you guy's, email me at:
[email protected].
