Input and output transformers are installed & included in these modules.

 As you can see the build quality is fantastic.

 

These modules are in excellent working condition  and sound great.

The 1541 is a great sounding EQ with a very open top end , solid bottom and extremely quiet.

 

 

I have been asked what is the difference between the 1540 and the 1541 ADM EQs besides the color. They have an identical EQ circuits with most 1540 using metal can ICs and the 1541 using standard 8 pin dip ICs. Same ICs same components, same circuits. The ADM 1541 have sockets for its ICs so it can  be upgraded with Burr Brown , Analog Devices or National parts if so desired. The 1541 is designed to be remote controlled and has a circuit to activate the EQ from outside of the module or from the front panel. The switch on the module is non latching and is push on push off with a LED to indicate that the EQ is engaged .     Other combos, Equalizers , Compressors, and Mic pres are available as well as raw modules.   See my Ebay Store for more   VPA-ADM RACKED AND READY FOR STUDIO USE MIC PRES EQUALIZERS AND COMPRESSORS 

 

 

Up for  auction ADM 1668-4LN  and ADM-2668-4 Four channel racked mic preamps.

 

In my store Dual 2780/1540 ADM Channel Strips .

 

All ADM racked and ready to use ADM Systems are guaranteed for 30days.

All shipping is the customers responsibility.

ALWAYS BUYING

I am always looking for Vintage Electronics lots for sale. Items I buy include -Broadcast Radio and TV equipment- HAM Radios & Accessories - Military Radios & Accessories - Test Equipment (New or Used) - Vacuum Tube Radios (working or nonworking) - Vintage Stereo - Vacuum Tubes & anything else that you may have similar to the above list. I will travel to you anywhere in the Lower 48 States. I always work a fair deal with the seller & I always pay with cash. If you are thinking of downsizing & are afraid of "giving" away your items, please email me with a list including makes/models for a fair price.

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 ADM booster cards ( like API-312 cards) are about 55db of gain except the 668 which is all transistor 40db of gain. ( no discrete opamp)
The 780/2780 input modules have an IC after the discrete opamp to get the extra 20db.

The 668 card all transistor (friends say they are Neve like ?) O-12 input transformer same as 1176
The 1668 card UTC O-8  input transformer>discrete opamp>output transformer.
The 2668 card UTC O-8 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.