Audio Input and
Monitoring Center
"The Model 4010 Companion"
Model 4011
5 August 2010
This unit was designed as a companion to our Model 4010, “The Restoration Preamp”TM.
The 4011 adds features to the 4010 but it also does a few other things as described in this specification sheet and in the User Guide.
INPUTS: Three stereo phono inputs using six RCA connectors plus three binding posts (case common) on the rear panel. The cartridge load resistance for each input can be set using an on-board DIP switch to 20, 100, 200, 470 or 47 kohms. The gain of Channels 1 and 3 can be set using an on-board DIP switch to 0, 5, 10, 15 or 20 dB. The Channel 2 input can be set to 0, 6, 12, 18 or 24 dB gain. These selections will match virtually all MM and MC cartridges. A switch setting diagram is in the User Guide and on the underside of the top cover plate.
A front panel rotary switch selects the active channel by activating a (one-of-three) on-board DC operated relay. Each channel has an independent gain control on the front panel to set the gain from the selected maximum to 4 dB below maximum. Having constant volume makes it easier to compare cartridges. These three controls are labeled INPUT LEVEL MATCH.
A front-panel toggle switch directs the Channel 1 input to either the Channel 1 or Channel 2 pre-amplifier as an additional means of comparing cartridges or playback systems.
The selected stereo channel output goes to the Channel Balance circuit board.
CHANNEL BALANCE: The channel balance control (single-turn, front panel) allows you to equalizes the left and right output voltages from the pickup cartridge. Balance is indicated on a zero-center, front panel meter. Balance range is zero to about +5 dB with an accuracy of ±0.5 dB over the frequency range of 500 to 1500 Hz as set by and on-board bandpass filter. True RMS detectors are used to provide maximum balance accuracy.
The importance of matching the left and right cartridge output voltages before listening to or recording mono records is discussed in an upcoming audioXpress article. The balance meter can also be used to optimize the cartridge alignment as described in the User Guide.
The buffered (unity-gain amplifier) stereo output from the balance circuit board goes to three stereo outputs on the rear panel (RCA connectors). These are labeled L-R BALANCED STEREO OUTPUTS and they can be used to drive other preamps or test instruments as needed. Each output is isolated with a 100 ohm series resistor. (One of these outputs goes to the Model 4010 input.)
HEADPHONE AMPLIFIER: The mono output (duplicated on the left and right channels) from the 4010, the L-R balanced stereo input or an external stereo input (rear panel RCA connectors) can be selected by a front panel switch to drive the headphone amplifier. It has a balance control, a loudness on/off switch and a volume control – all on the front panel. It has two stereo, front panel, output connectors: a 1/4 inch jack and a 2.5 mm jack (in parallel).
POWER: The unit is powered from a 24 VDC (500 mA or higher, furnished) wall power supply. For customers in the United Kingdom, Europe, Asia and Australia, a “universal” wall supply is furnished with an appropriate mains plug. Input: 100 to 240 VAC, 47 to 63 Hz. Output: 24 VDC, 600 mA.
PHYSICAL: The unit is housed in a 2RU rack-mount enclosure, 10 inches deep. Weight is 6.5 pounds. The unit is furnished with four rack-mount screws and four stick-on rubber feet for shelf or desk-top use.
PRICE: See price list
Model 4011 Rear View
Typical model 4011 noise “floor” – 20 dB gain, 47 kohm input impedance, input open.
