*Nerd Alert* When I first acquired a Pultec LCS-2, which is a two channel passive low cut filter, I noticed that when I inserted the filter at any frequency there was actually a sizable boost in the the frequency just above the one that was selected. Perplexed by all this I took to the internet. A thread on GS told the story of an engineer that had a “modified” version of this very unit, and would use it on kick to fatten up the sound. So I took a peek inside of my unit, and it didn’t look like anything was tampered with. So I did more research, and while looking at buying some cables to connect the terminal strip of the unit to my patchbay I noticed that sellers were adding in a 600ohm resistor. The sellers, knowing that if a piece of gear has a terminal strip on it it had to be old, and the standard for older gear was to have 600ohm load at output. With this insight I searched my tool box for a 600ohm resistor, found a 640ohm one, and strapped it across the + and - terminals of the output, and viola, the filter worked as it was supposed to. I started looking up manuals for vintage equipment and noticed that most say “Output Impedance 600 ohms” So today I took to seeing if my Pultec EQP-1A needed the same. In the manual it states that the output impedance can be 600, 250 or 150 ohms. I then played some music through the unit and would put the resistor across the terminals to see if I could hear a difference. After hearing no real change in the sound I figured that it wasn’t necessary. I then took to the internet again as I was puzzled by this. After reading an eBay auction for the above mentioned cables to connect this unit I noticed that it said it was due to a resonance that can occur in higher frequencies. So I ran pink noise through the unit and alas, I could hear a slight boost in the high frequencies without the 600ohm resistor. In conclusion, if you have vintage audio equipment, check the manual for the output impedance, if it states that the ohmage of the output transformer is 600ohm, throw a resistor on! Super nerd shit huh?! #pultec #pulteceq #eqp1a #vintageaudio #recordingstudio #tubeequipment #music #musicproduction @pulsetechniques (at Brick By Brick Studios) https://www.instagram.com/p/B5GwKGgFjIG/?igshid=1nsaug5bqczel
