Ok, so i just did a session at a studio here in town that has the most amazing collection of crazy old outboard stuff - handmade Manley veri-mu's, blue stripes, 1178's, racks of McCurdy tube pre's, Tele tube pre's, a neve 8056, a whole mess of pultec's and mccurdy pultec style eq's…
one of the things i was most shocked by was the pultec HLF's - they are just simple, variable high and low pass filters that just sound amazing…
so i did some digging, and got to thinking - it seems most of what you read now a days, and around here suggest using RC circuits for high and low pass, but in both the Tremaine's Audio Cyclopedia and the RCA Radiotron book they talk almost exclusively of constant K LC circuits…
in perusing thru some old schematics i found that a lot of the older designed utilized LC filters - neve did a variable high pass with a tapped inductor… Helios used some LC filters - AND - these pultecs are LC as well:
http://www.gyraf.dk/schematics/Pultec_HLF3.pdf
so for the channel strips I'm working on I had settled on simple, single stage RC filters for both high and low, but now i am thinking:
is there an advantage to RC circuits other than the low cost and small size?
Is there a reason that LC circuits have kind of fell out of favour?
Or have they?
I'd love to get you guy's insight on this - I did the math and have started sourcing the stuff - figure i'll give em a shot in my prototype box…
thanks guys,
Timothy
one of the things i was most shocked by was the pultec HLF's - they are just simple, variable high and low pass filters that just sound amazing…
so i did some digging, and got to thinking - it seems most of what you read now a days, and around here suggest using RC circuits for high and low pass, but in both the Tremaine's Audio Cyclopedia and the RCA Radiotron book they talk almost exclusively of constant K LC circuits…
in perusing thru some old schematics i found that a lot of the older designed utilized LC filters - neve did a variable high pass with a tapped inductor… Helios used some LC filters - AND - these pultecs are LC as well:
http://www.gyraf.dk/schematics/Pultec_HLF3.pdf
so for the channel strips I'm working on I had settled on simple, single stage RC filters for both high and low, but now i am thinking:
is there an advantage to RC circuits other than the low cost and small size?
Is there a reason that LC circuits have kind of fell out of favour?
Or have they?
I'd love to get you guy's insight on this - I did the math and have started sourcing the stuff - figure i'll give em a shot in my prototype box…
thanks guys,
Timothy