Racked Pair ADM  668 Discrete Transistor  Mic Preamps,  Transformers in and out. Internal PS 110V or 220 Volt Option. Discrete Transistor   Based Mic preamp Plug and Play ADM-668 console booster cards from a 1960's era 700 Series Console.
Racked and refurbished ready to use.
Transformer balanced in and out. Internal Power Supply 110 or 220 Volt 220 Volt option requires additional shipping time. Fixed Gain 55db  gain of the amplifier, with a 20db input pad
 Output attenuator to keep from overloading your convertors, Drive the input hot and attenuate  the output going to your A/D convertors.
48V Phantom, Pad , Polarity switch , and Impedance switching 250/50 ohms. We are laying out the faceplates to one side of the front panel to accommodate  the ability to up date your 2 channel mic pre to a 4 channel mic pre in the future . Send back your 2 channel 668 and we will add 2 more channels $450 plus shipping both ways .
Four channels versions are available to order.These modules are excellent mic preamps.
They  are extremely musical. The ADM 668 booster cards are racked side by side in a 1 space chassis with power supply and internal Toroidal transformer. The chassis is a one unit 19" rack mount with the power supply installed and input voltage switchable for 110V or 220V.
ADM custom discrete 5 Transistor preamp with a design very similar to that of a AM16.  All 6  electrolytic caps have been replaced , this is a very high quality build .
Single ended 24V power supply is included in the enclosure with an internal toroidal 30V transformer .
 ADM  668 have  both Input and Output Transformers by UTC  O-12 (1176 input transformer)  and ADM custom OPT.
 
These booster  cards are like a AM16 with more character,  they  come from a late  1960's ADM 700 series Console ,
  See my Ebay Store for more VPA-ADM RACKED AND READY FOR STUDIO USE MIC PRES/  EQUALIZERS/ HI-PASS LOW PASS FILTERS/NOISE GATES  AND COMPRESSORS.
Coming soon empty racks to put your ADM modules in .
 Up for auction ADM-2 channel 1668.
 
ADM 1668-4LN and ADM-2668   2 and 4 Four channel 1 and 2 space racks .
 In my store Dual 2780/1540 ADM Channel Strips . ADM-1541/1540 EQs.
 ADM 320/1320 Compressors. ADM 310/1310 Noise Gates .
ADM 1551 Low Pass High Pass filters.The ADM 1540 EQs , 320/1320 Compressors, 310/1310 Noise Gates and 1541 Filters all use the same pin outs
and can be combined in any combination in our 1 space Racks . All ADM racked and ready to use ADM Systems are guaranteed for 30days.
All return shipping is the customers responsibility.I have been getting a lot of questions about the ADM booster cards and the 320/1320 Compressors
so here is a little more info on the above products.

The 2668 is part of the 780/2780 series console booster cards. from late 1970's through the Mid 80's The 1668 is part of the 770 series consoles booster cards.from early 70's to late 70's.
The discrete opamp in the 1668 is very much like a 2520 API ( I had a ADM TV 32 that had all 2520's replacing ADM opamps) the input transformer is the same on both cards . The output transformers are different.To add more confusion the ADM 668 cards are all discrete (5 transistors) a UTC O-12 ( same as an 1176) and a custom output transformer.
These were in late 1960's to very early 1970's consoles the 700 series console..All of these booster cards ( like API-312 cards) are about 55db of gain.
The 2780 input modules have an IC after the discrete opamp to get the extra 20db.
Unfortunately it requires a ton of labor to get them into a real usable state.
Lots of rewiring and mods , lots of time. and I can't get what they are worth so I am not building( modifying) them any more.The 668 card all transistor (friends say they are Neve like ?)
The 1668 card UTC input transformer>discrete opamp>output transformer.
The 2668 card UTC input> later discrete opamp> different output transformer.
The 2780 has the same input Xfrm same discrete opamp ( as 2668) from here it differs as it goes into a 4 transistor class a output driver to the same output transformer as the 2668..
The 1922 Card has the same output transformer driven by the same 4 transistor output circuit but it has a 5534 IC instead of the discrete opamp.
with the same input transformer as the 2668.
This card is a candidate to put a dip socket to discrete opamp adapter in and make it the discrete section of the 2780 ( or at least make it the way we mod the 2780 to be all discrete ( eliminates the additional +20db IC gain.)
The Compressors and the Noise Gates were designed to be on the buss . So they are rare buss compressors as most ADM consoles were only 4 buss plus the stereo buss. Not all boards had them installed, very rare option on the ADM consoles.