1K Notch filter?

Post: # 12477Unread post **opcode66** Sun Jan 30, 2011 6:09 pm

I'm trying to push as much volume as I can on cuts. However, when I do some elements of the program material will clip. Typically this is vocal stabs or piano chord stabs. I've noticed on Frequency Analysis that these stabs tend to be hot in the 1K range.

I know that the resonant frequency of the SX74 head is 1K. I'm wondering if the resonance is what is causing me to have the crunchy sounds. I tried cutting with a conservative notch filter at 1K and that helped. I'm going to try again with a more severe notch at 1K.

Has anyone else had this issue? Not sure if others are catering to clients who want a lot of volume. Anyone I cut for will want this as a standard.

Input is more than appreciated here. Anyone have some insight?

Post: # 12478Unread post **petermontg** Sun Jan 30, 2011 6:17 pm

where about in the chain are you analyzing. pre or post cut?

Post: # 12480Unread post **opcode66** Sun Jan 30, 2011 6:59 pm

Analyzing either the Input or Feedback monitor selection on VG74 amp rack. Pre cut for Input, post cut (technically) for Feedback.

Post: # 12489Unread post **markrob** Mon Jan 31, 2011 9:47 am

Hi,

If its clipping in the signal path prior to head, then you have a gain staging problem. How are you determining that there is actual clipping happening (e.g scope, peak meter)? If the feedback path is clipping, that would indicate you are running open loop during the overload. At system resonance, the required drive to the head is at a minimum and the amount of feedback is at a maximum. I don't see the need for a notch filter unless the source material has major problems.

Mark

Post: # 12658Unread post **opcode66** Sun Feb 06, 2011 7:06 pm

remastered the source material and problem solved... Thanks for the input.

Post: # 12662Unread post **petermontg** Mon Feb 07, 2011 6:45 pm

nice one.

was going to say check valves since you were driving for maxi output (if you had any in pre chain) when the clip they carry a load of gain.

problem solved. what was the problem with master may i ask

Post: # 12663Unread post **opcode66** Mon Feb 07, 2011 8:26 pm

Well, a couple of things. Yes, keys and vocal stabs were the culprit. I had a multi-track master. So, going back and correcting individual elements was a piece of cake.

Also, after speaking with a number of other Trolls I realized I didn't have a severe enough rolloff on the high end for cutting. Didn't cause a problem at low volume (-3). But when cutting at 0 with peaks at +2 it became very apparent.

I changed by rolloff to start at 16K and decrease by 24db/octave. Seeing as though the frequencies in the high end get excited by the RIAA curve, if loud they get cut clipped. But, if you deemphasize a bit and then cut loud with RIAA on you get loud highs with no clipping cut.

Even though playback tables have reverse RIAA (de-emphasis), if you disc was cut with clipping, no amount of de-emphasis will fix the clipped audio. The trick is to de-emphasize a little before committing to disc.

This is all a learning a experience for me for sure. Think I'm doing ok though. I've only had my baby since October. But, in that short time I think I've come a very long way. And, hey, I didn't even smoke my head... a common rookie mistake.