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Post by tonycamphd on Nov 19, 2013 20:15:24 GMT -6
I'm wondering how much you fella's do hi/low pass filtering(really interested in lo pass applications?), i've read some guys use it on every single track, what kind of tracks do you find it to be most useful, how far might you take it, and what filters are your favs for vibe or transparency?
thanx for any input
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Post by svart on Nov 19, 2013 21:04:32 GMT -6
I almost always do a low pass or at least a high shelf turned down on the guitars and bass, unless it's acoustic stuff. Nothing but fizz and hiss above 8k-ish on those things. Never to high passing on overheads, might do some on toms and kick and snare depending on the bleed.
Sometimes on vocals too if the highs are too much.
That's about all.
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Post by cenafria on Nov 20, 2013 3:19:21 GMT -6
I'm wondering how much you fella's do hi/low pass filtering(really interested in lo pass applications?), i've read some guys use it on every single track, what kind of tracks do you find it to be most useful, how far might you take it, and what filters are your favs for vibe or transparency? thanx for any input I use the HPFs on our modded 32 series quite often (the filters are stock). From memory, on the last session they were used on the kick drum beater mic, on the snare down mic, both batter side tom mics, the ride spot mic, the drum room mics and the condenser on the bass cab. Generally, when recording I'm going for transparency, trying to hear things as close as possible to how I hear them in the room (but always keeping in mind the band's aesthetic criteria). The LPFs I use only occasionally. Last time was a mix session of mostly electronic music brought to me by a musician from his home studio. I ended up using them on a surprising amount of tracks, mostly to try to make virtual synths sound heftier. The filters on the Harrison are far from subtle. I do find them very useful though. |
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Post by svart on Nov 20, 2013 8:13:20 GMT -6
That brings up a good point. I also find myself using a lot of LPF on tracks that others bring to me due to the unusual amount of hiss that is usually present on these tracks due to poor mic placement, poor gain staging or the cheap guitar-center-special preamps/recorders. A lot of these seem to be synth tracks and stuff like that. It also helps the noise from poor D/A conversion on most keyboards sound more natural.
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Post by jazznoise on Nov 20, 2013 8:51:07 GMT -6
I'll use HPF's on source mics where I know any low end is not central to source and may cause phase issues - for instance I'll probably cut below 100Hz on a snare top mic (and the bottom if I didn't record it, but I usually set up my bottom mic to also be the kick beater mic). I might cut some low end out of guitars from time to time. Hi hats sometimes need it. That's sort of it - if I didn't want much bass on something I pick a bass light microphone.
Sometimes on overheads or on room mics if I'm getting "Night club bass".
LPF? Not unless it's for effect. Even for parallel processing unless I won't NO high end, I'd use a shelf over a LPF. If I wanted a dark sound, I'd hope I used my ribbons and a bit of desk EQ first.
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Post by tonycamphd on Nov 20, 2013 10:18:26 GMT -6
good stuff fella's, thanx a lot
i'm pining to build the "harrison ford filters" diy project, based off the harrison console, cenafria's got the real deal! awesome, the general consensus from the guys at groupdiy who've built them are the same as his, they are NOT subtle or really transparent, but have a great vibe to them? cant wait to find out.
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Post by jcoutu1 on Nov 20, 2013 10:25:57 GMT -6
good stuff fella's, thanx a lot i'm pining to build the "harrison ford filters" diy project, based off the harrison console, cenafria's got the real deal! awesome, the general consensus from the guys at groupdiy who've built them are the same as his, they are NOT subtle or really transparent, but have a great vibe to them? cant wait to find out. I use hi pass filters all the time. Guitars, vox, horns, overheads, harp, keys, all kinds of stuff. Clean up the lows where you don't want a buildup.This vibes stuff is such a strange concept to me. Using filters for vibe? I think of them more as a utilitarian tool than something to add vibe. Give me comps or even some unique eq curves to add some vibe, not filters. |
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Post by tonycamphd on Nov 20, 2013 10:45:05 GMT -6
good stuff fella's, thanx a lot i'm pining to build the "harrison ford filters" diy project, based off the harrison console, cenafria's got the real deal! awesome, the general consensus from the guys at groupdiy who've built them are the same as his, they are NOT subtle or really transparent, but have a great vibe to them? cant wait to find out. I use hi pass filters all the time. Guitars, vox, horns, overheads, harp, keys, all kinds of stuff. Clean up the lows where you don't want a buildup.This vibes stuff is such a strange concept to me. Using filters for vibe? I think of them more as a utilitarian tool than something to add vibe. Give me comps or even some unique eq curves to add some vibe, not filters. you know i was/am right there with you on that, i'm a linear phase hp/lp guy, but the general idea with the harrison filters is they throw a curve at the cutoff points(not unlike that pultec thing?) that do "something" thats supposed to be very pleasing to the ear, supposedly one of the reasons people love the harrison consoles is because of the great "sounding" filtering. Maybe cenafria can speak more to this? Danderloo also, but coming from me, it's only what i've read. |
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Post by jazznoise on Nov 20, 2013 10:48:08 GMT -6
good stuff fella's, thanx a lot i'm pining to build the "harrison ford filters" diy project, based off the harrison console, cenafria's got the real deal! awesome, the general consensus from the guys at groupdiy who've built them are the same as his, they are NOT subtle or really transparent, but have a great vibe to them? cant wait to find out. What order filter are they? It's quite possible the "Vibe" comes from some resonance. The same way you can use the HPF in the MS-20 to cool effect. If the schematic is this:  Then I could certainly see those TL072's adding some "Vibe". IC1A could see as low as 300ohms impedance with both Hipass knobs turned to 0K. When ever I breadboarded buffer stages with TL07X series I found the distortion shot up if loaded with less than 2k. Or am I reading this schematic like a crazy person? |
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Post by tonycamphd on Nov 20, 2013 10:52:03 GMT -6
good stuff fella's, thanx a lot i'm pining to build the "harrison ford filters" diy project, based off the harrison console, cenafria's got the real deal! awesome, the general consensus from the guys at groupdiy who've built them are the same as his, they are NOT subtle or really transparent, but have a great vibe to them? cant wait to find out. What order filter are they? It's quite possible the "Vibe" comes from some resonance. The same way you can use the HPF in the MS-20 to cool effect. Then I could certainly see those TL072's adding some "Vibe". IC1A could see as low as 300ohms impedance with both Hipass knobs turned to 0K. When ever I breadboarded buffer stages with TL07X series I found the distortion shot up if loaded with less than 2k. Or am I reading this schematic like a crazy person? jazz, I don't know the answer to your Q's, but i pm'd danderloo on this, and asked him to chime in, he has quite a bit of knowledge on this i believe, he provides the pcb's and cases for the "harrison ford filters" diy kits. |
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Post by jazznoise on Nov 20, 2013 11:10:43 GMT -6
What order filter are they? It's quite possible the "Vibe" comes from some resonance. The same way you can use the HPF in the MS-20 to cool effect. Then I could certainly see those TL072's adding some "Vibe". IC1A could see as low as 300ohms impedance with both Hipass knobs turned to 0K. When ever I breadboarded buffer stages with TL07X series I found the distortion shot up if loaded with less than 2k. Or am I reading this schematic like a crazy person? jazz, I don't know the answer to your Q's, but i pm'd danderloo on this, and asked him to chime in, he has quite a bit of knowledge on this i believe, he provides the pcb's and cases for the "harrison ford filters" diy kits. Cool! I'm excited to see how wrong I am, if that makes any sense. I'm no filter guy, though I'm guessing that the 50K is a duel gang wired so that when one gang is at 50K the other is at 0 and vica versa. Curious to see someone explain the M.O at any rate, it might enlighten us on the mojo. |
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Post by Ward on Nov 20, 2013 11:25:37 GMT -6
I thought this was going to be a thread about cigarettes...
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Post by cenafria on Nov 21, 2013 5:52:34 GMT -6
I use hi pass filters all the time. Guitars, vox, horns, overheads, harp, keys, all kinds of stuff. Clean up the lows where you don't want a buildup.This vibes stuff is such a strange concept to me. Using filters for vibe? I think of them more as a utilitarian tool than something to add vibe. Give me comps or even some unique eq curves to add some vibe, not filters. you know i was/am right there with you on that, i'm a linear phase hp/lp guy, but the general idea with the harrison filters is they throw a curve at the cutoff points(not unlike that pultec thing?) that do "something" thats supposed to be very pleasing to the ear, supposedly one of the reasons people love the harrison consoles is because of the great "sounding" filtering. Maybe cenafria can speak more to this? Danderloo also, but coming from me, it's only what i've read. I can't really help interpreting the schematic, but I can clarify what I mean when I say they are not subtle. When you sweep the low pass you hear a peak sweeping through the frequencies that reminds you of a "polite version" of an analog synth filter sweep. You can find a position for the filter pots where the signal will disappear. The eq, on the other hand, is hardly extreme, specially when compared to many 80's mixers. My experience is that it is hard to make sound artificial or weird. The truth is that I have been working with this eq/filters for twelve years (since I've had the console) and it is my "go to" eq. I can't say if this is a testament to the quality/versatility of the circuit or proof that I have worked with the console for a long time. It is the one I use the most when tracking or mixing. For reference I'll state that I also have api 550a and b (both current versions), two electrodyne 511, two Avedis e27, two racked Siemens Sitral modules (the "newer" ones, with the colourful knobs), two Eckmiller w86a and two Valley People MaxiQ modules. I use plugin eq once in a blue moon. Perhaps filtering a reverb send on a very complex mix on protools or on a backing vocal submix on something I didn't track that shows up at the studio with 77tracks for a four piece band. I mention this so you can get an idea of what my MO is. I'll try to post the original schematic, it looks prettier than the one posted above ; ) |
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Post by tonycamphd on Nov 21, 2013 10:03:33 GMT -6
Awesome! i would love to see that schemo, I've never had the pleasure of working on a harrison, but the few i've talked to who use them, (paraphrase) say they ease in to the music, just like another instrument in the band. Bruce Swedien uses one to this day i think? I look forward to the day i get to play with one of these bad boys 8) |
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Post by svart on Nov 21, 2013 10:23:07 GMT -6
good stuff fella's, thanx a lot i'm pining to build the "harrison ford filters" diy project, based off the harrison console, cenafria's got the real deal! awesome, the general consensus from the guys at groupdiy who've built them are the same as his, they are NOT subtle or really transparent, but have a great vibe to them? cant wait to find out. What order filter are they? It's quite possible the "Vibe" comes from some resonance. The same way you can use the HPF in the MS-20 to cool effect. If the schematic is this: Then I could certainly see those TL072's adding some "Vibe". IC1A could see as low as 300ohms impedance with both Hipass knobs turned to 0K. When ever I breadboarded buffer stages with TL07X series I found the distortion shot up if loaded with less than 2k. Or am I reading this schematic like a crazy person? Looks like 2pole filters. TL074 in unity buffer mode like 1A and 1C won't add any "vibe". The TL0xx series is pretty neutral when used as unity buffering. The only issues/problems arise when they are used in high gain situations. And yes, various opamps have ranges of input/output/feedback impedance that they like, which is usually listed in the datasheet. Just one of the many reasons you can't just go swapping out opamps in things and expecting better performance. |
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Post by svart on Nov 21, 2013 10:27:27 GMT -6
jazz, I don't know the answer to your Q's, but i pm'd danderloo on this, and asked him to chime in, he has quite a bit of knowledge on this i believe, he provides the pcb's and cases for the "harrison ford filters" diy kits. Cool! I'm excited to see how wrong I am, if that makes any sense. I'm no filter guy, though I'm guessing that the 50K is a duel gang wired so that when one gang is at 50K the other is at 0 and vica versa. Curious to see someone explain the M.O at any rate, it might enlighten us on the mojo. You can see that the pin numbers are 123 on one instance and 456 on the other, meaning that they are probably ganged, although the drawer of the schematic generally would add a line to the wipers of each to show the ganging. |
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Post by svart on Nov 21, 2013 10:41:59 GMT -6
good stuff fella's, thanx a lot i'm pining to build the "harrison ford filters" diy project, based off the harrison console, cenafria's got the real deal! awesome, the general consensus from the guys at groupdiy who've built them are the same as his, they are NOT subtle or really transparent, but have a great vibe to them? cant wait to find out. What order filter are they? It's quite possible the "Vibe" comes from some resonance. The same way you can use the HPF in the MS-20 to cool effect. If the schematic is this: Then I could certainly see those TL072's adding some "Vibe". IC1A could see as low as 300ohms impedance with both Hipass knobs turned to 0K. When ever I breadboarded buffer stages with TL07X series I found the distortion shot up if loaded with less than 2k. Or am I reading this schematic like a crazy person? So this looks like a couple of VCVS(voltage controlled voltage source) filtes. The variable positive feedback and ganged shunting resistance will cause some peaking or negative peaking around the cutoff points. Possible source of the *vibe*. |
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Post by jazznoise on Nov 21, 2013 15:14:37 GMT -6
What order filter are they? It's quite possible the "Vibe" comes from some resonance. The same way you can use the HPF in the MS-20 to cool effect. If the schematic is this: Then I could certainly see those TL072's adding some "Vibe". IC1A could see as low as 300ohms impedance with both Hipass knobs turned to 0K. When ever I breadboarded buffer stages with TL07X series I found the distortion shot up if loaded with less than 2k. Or am I reading this schematic like a crazy person? So this looks like a couple of VCVS(voltage controlled voltage source) filtes. The variable positive feedback and ganged shunting resistance will cause some peaking or negative peaking around the cutoff points. Possible source of the *vibe*. Vibe was a joke reference to the idea of a TL07X driving anything below 2K with low distortion. They just don't do it. I might be reading the circuit wrong, but I can't see where the power is coming from to drive that load. I'm glad someone else thought it was a 2 pole. So I'm guessing VCVS filters are a higher Q than your standard Butterworth? |
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Post by svart on Nov 21, 2013 15:52:15 GMT -6
They can still be Butterworth which only defines the response of the frequency of the passband being as flat as possible. typically most simple filters are going to be Butterworth or Bessel unless you have multiple poles affecting the other poles in overlapping ranges, or other things that affect Q of the filter elements.
The input impedance of the DRV134pa is listed as 10K ohms.. The DRV134 is the part that is driving the output load of this setup.
I also see that the TL074 doesn't actually list a specified output impedance, however all of their specs reference a load of 2K when testing, so I suspect you aren't far off from the lowest impedance this part can drive.
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Post by jazznoise on Nov 21, 2013 17:50:52 GMT -6
If you wan't to hear what an IC shitting itself sounds like, stick a 1K load across a TL074. I'm surprised they're being used here, a 5532 could probably replace them. But now I'm sounding like one of THOSE guys.
Svart, you don't have any good literature on filter design you'd recommend? It really is where I fall down on things. I mean, amongst all the other things I fall down on this is the worst.
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Post by cenafria on Nov 22, 2013 2:10:18 GMT -6
Here are some scans of the schematic.   |
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Post by svart on Nov 22, 2013 8:45:26 GMT -6
If you wan't to hear what an IC shitting itself sounds like, stick a 1K load across a TL074. I'm surprised they're being used here, a 5532 could probably replace them. But now I'm sounding like one of THOSE guys. Svart, you don't have any good literature on filter design you'd recommend? It really is where I fall down on things. I mean, amongst all the other things I fall down on this is the worst. NE5532 probably wouldn't care much about being used in this circuit so scaling the feedback networks is probably not necessary to use it. If you paralleled up a couple of them, you could drive 600R loads pretty easily and do away with the DRV134, unless you wanted differential outputs. As for filters, I typically use multipole LC filters since I do RF design and I use programs like Spice, Matlab, Genesys/Eagleware, etc to do simulation, but I generally find most of my information on the internet if I don't already know what I want to do. There are plenty of whitepapers and application notes from most OpAmp manufacturers that show you neat filters and tricks with their parts, which also have the secondary benefit of showing you the proper feedback values and things for good noise performance. There are also some freeware programs that can help you design these filters. |
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Post by tonycamphd on Nov 23, 2013 23:27:46 GMT -6
Mr Bruce talks about the harrison here, what i found most interesting is when he mentioned the filters on the board, he seemed to be most excited...? i gotta try me some of these filters.
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Post by tonycamphd on Feb 6, 2014 9:51:17 GMT -6
Bumping this thread because of littlesicily's thread, I still haven't built these, unit7 ... Paul, u use a Harrison don't u? Would love to hear some of ur thoughts on those filters? |
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Post by unit7 on Feb 6, 2014 11:07:01 GMT -6
Bumping this thread because of littlesicily's thread, I still haven't built these, unit7 ... Paul, u use a Harrison don't u? Would love to hear some of ur thoughts on those filters? Hey Tony! I'm afraid I'm not an experienced enough engineer to say much. I wouldn't dare even say if there is a typical Harrison sound. My guess is that my Series 12, which was the last large format analog they manufactured, probably sounds different than the old 24- and 32 series. But perhaps there are some similarities anyway. Sound is so crazy subjective I find it hard to discuss, even if that's what people try to do all the time  Anyway, I look for the thing people call 'musical eq'. To me that's the kind that when adding a bit of treble to a voice or an acoustic guitar you start to smile, because it adds some sparkling or fairy dust that is more than just 'more or less treble frequencies' or mid or bass or whatever. To my taste that's generally more Neve than SSL. I had some experience with the Series 12 working at Rainbow studios in Oslo but never had the time to really listen to the eq, much because we only tracked and I use to be very moderate with eq while doing that. So prior to buying my console I took a flight over to Oslo with two projects that I had produced and had an hour to play with the console and the eq in particular (btw, early morning before The Man Jan-Erik Kongshaug started his working day). I tried to keep the cool and be unbiased knowing that I'd probably have to stick with this decision for the rest of my career. But there it was again, the smile on my face, defences down  . Now after more than 5 yrs with it, i still feel it's more towards Neve than SSL. 'Musical'  style eq, a tad bit cleaner and more grabby than Neve IMO. Ok, that was my Harrison Eq Story! |
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. Now after more than 5 yrs with it, i still feel it's more towards Neve than SSL. 'Musical' 
style eq, a tad bit cleaner and more grabby than Neve IMO. Ok, that was my Harrison Eq Story!