EQ setting recommendations?

[cymbalism]

picked up a behringer ultra graph pro GEQ3102 today and started equing some cuts but i'm running into an issue with flutter on silent passages kinda like the bass is WAY overdriven. i've already cut the low at 40 and the high at 16 and my test cuts sound good on the high and mid range end after a little tweaking here and there but my bass is causing me grief. i'm cutting some rock right now and will eventually move onto more electronic based tunes once i can get this issue resolved.

i've equed the low end not getting any higher on 100 and 125 than -4db and the remainder rolled off to -6db and my input level to the grampian magnetic type c is hitting just at +3db.

any advice for me? i'm getting frustrated so i'm taking a break

[markrob]

Hi,

How are you dealing with the RIAA curve? The Gramian is flat vs. velocity, so the RIAA curve applied during reecording is the mirror of the published curve for playback with a magnetic pickup. Are you intending to aproximate this using the EQ? This might be doable by aproximation using the graphic EQ, but, I'd look into doing this ahead of the EQ with a proper filter. Then just use the EQ sparingly to season to taste. Flo provided a nice simple circuit for a passive IRIAA filter. You will need about 20db of makeup gain in your signal path if you go this route. He also provided the schematic for the Jamaika pre, which is acitve. You'll need some skills with building electronics to make this. If you are pre-mastering digitally, I developed a VST plugin the performs the filter in software and would be glad to send it your way if you PM me with your email info. Simon had problems getting this to work with Audacity, but I've had no problem with it using with any program that can support the VST plugin standard.

Mark

[cuttercollector]

Hi,

the RIAA curve applied during reecording is the mirror of the published curve for playback with a magnetic pickup.

Mark

Did we not have a big discussion with CD4 somewhere on this forum before that this is not actually the case? Something to do with the additional constant amplitude vs. constant velocity curve of the magnetic playback cartridge.

It is possible to use an outboard record eq and an RTA to achieve more or less flat playback response using your favorite cartridge and phono preamp as a reference. Set an approximate eq with bass cut and treble boost, cut pink noise at a moderate level - NOT at your "zero", then playback into the RTA and see how you did. You might have an issue with some heads having enough eq adjustment range. And I am only talking about trying to get it reasonably flat through perhaps 60-10K. Don try to eq flat from 20-20K - you can't and something (typically the head) will give up if you push it to higher levels with that much eq.

[markrob]

Yes and no. CD4 indicated that the RIAA curve to be applied would be quite different than the often published curve if the cutter head or pickup was a constant amplitude device. In the case of pickups, we talked about ceramic devices, which are constant amplitude by nature. He indicated that many of the pro feedback style cutter heads are inherently constant amplitude as well (at least up to the primary system mechanical resonance point). In the case of the Grampian, it is a constant velocity device, so the curve to use is the velocity based one. If you look at Flo's circuits and the Grampian RA7 amp designed for this cutter, you'll see it has the typical HF boost, LF cut of the curve. I'd guess most of the open loop moving iron designs also work this way. The Presto 1C/1D does, but it turns out to be constant amplitude below 500 hz. due to the electical L/R time constant. So the RIAA curve only needs to deal with the boost starting at 2122 hz. I have a seperate plugin to handle this. Hope that clears some things up.

Mark

Mark

[motorino]

Hey Mark, do you have the active correct curve for the grampian? Do you calculated?

Cheers

[markrob]

Hey Mark, do you have the active correct curve for the grampian? Do you calculated?

Cheers

Hi,

I don't know if a fixed filter would work for all Grampian heads due to tolerance variations. That's where cutercollector's approach comes into play. I've used Har-Bal for this and it works well. As to level, as long as the RMS current fed to the head does not cause it to exceed it's power limits, you are good to go. You want to get as much level as possible on the disk to make sure you are well above the noise floor or you could end up EQ'ing wrong. As he said, don't try to push the upper/lower end of the response too far. If you are asking about the standard RIAA turnover points, they are easy to find on the net. (50, 500, 2122Hz).

BTW, very cool to see you cutting at a live event!

Regards,

Mark