Dynamic EQ?

Ive been thinking about trying to combine a VCA compressor with a parametric EQ circuit. not a multiband compressor, rather a dynamic EQ. there is a plugin I really like that does this, the sonalksis DQ-1. I like it for de-essing and also for low freq upward expansion. Has anyone done this already? Im thinking the best candidate for the EQ would be the s+o#n*tec/G*M&L circuit. ideally you would have flat response with no GR then as compression increases the filter gain gradually becomes whatever the boost/cut pot is set at. this is roughly acheivable by putting a VCA+inverter in parallel with the signal coming back to the summing node (the signal that goes thru the vactrol in an M.E.P.2.5.0). Im thinking an FMR RNC would make an ok comp for this purpose. any ideas?

mike

Search.

BSS DPR

Keef

PRE harmon DPR's sound best IMO. In the DPR manual it explains exactly how it works and has a block diagram... free download too.

Just a quickie thought I once archived in my head..

What if you had an LDR shunted to ground via series LC filter? That could work well for de-essing purposes. The Q would be nothing constant, but might sound cool..

RCA had a custom dynamic eq (I don't think it was ever marketed as a commercial product) used for their Living Stereo system. I think it was a two band, with varying bass/treble response at different dynamic levels. There was an AES paper (by Olsen) about it, though no schematics (only block diagrams) if I recall.

James

Always good to see a person trying to recreate their favourite plugin with real parts. Many people have that backwards!

What if you had an LDR shunted to ground via series LC filter?

Click to expand...

How about many series LC networks in parallel to ground? Probably ring like a telephone, lol.

The "Dynamic Spectrum Equalizer" was part of the RCA Dynagroove system.

http://www.aes.org/e-lib/browse.cfm?elib=754

thanks for the ideas
The DPR901 documentation was kindof helpful. Does anyone know for sure how they implement the "inverting VCA"? I bet it is a conventional monlithic VCA in parallel with a unity gain inverting stage. if not, why would they run a VCA at neraly full cuttoff all the time? They are usually optimized around the unity gain point.

The BSS unit looks useful, but I don't think it would be transparent enough for what I would want it for, mastering. maybe it would be worthwhile getting one and modding it, but that wouldn't be as much fun.

optos are appealing because you have more freedom choosing an EQ topoly. The opto auto-release might be useful in some applications, but I was thinking of a more general purpose, analytical type device. I sometimes use a very fast attack on a low frequency expander to add punch to badly recorded or overlimited music. an opto would never be fast enough for that.

Hmm, i Just remembered a simple PWM VCA I designed for a synth building friend a while back. it sure would be cool if you could use the EQ filter to help smooth the post-PWMed signal. I got some more thinking to do.

mike

the 901 is good. It's clearmountains secret to a good vocal. Not so much a secret now :twisted: but anyway I would imagine it would be good out of the box for mastering but then again wait no it wouldn't as IIRC non stepped pots.... would be a good mod then it could be a mastering version.

[quote author="pucho812"]no it wouldn't as IIRC non stepped pots.... would be a good mod then it could be a mastering version. [/quote]

stepped pots are overated. it is a nice feature but IMO not totally necesary,not for me. If I have to do a recall Id rather just do it over from scratch. I'm more concerned with the fidelity.

mike

You're right Dave, my mistake. Dynagroove not Living Stereo.


[quote author="NewYorkDave"]The "Dynamic Spectrum Equalizer" was part of the RCA Dynagroove system.

http://www.aes.org/e-lib/browse.cfm?elib=754[/quote]

[quote author="mikep"]why would they run a VCA at neraly full cuttoff all the time? They are usually optimized around the unity gain point.[/quote]
Yep. It's subtractive, so even an awful 5% distortion at -60dB is reduced to an equivalent 0.005%... At full-on, where the VCA is optimised and hopefully doing much better, the effect is more critical, which works out very neatly!

Don't dismiss the DPR because you don;t think it looks like it could be good on paper... That's a terrible way to make decisions! :wink: The 901 is a mighty mighty bit of gear, and -if you only want to make sublt changes, you can probably do a 3:1 recombination using a simple mixer circuit and divide any negative side effects by a factor of 4...

Think about it. -Rent one. Do whatever, but to think you might easily build a better mousetrap might well be folly.

My $.02

Keith

[quote author="SSLtech"]
Don't dismiss the DPR because you don;t think it looks like it could be good on paper... That's a terrible way to make decisions! :wink: The 901 is a mighty mighty bit of gear[/quote]

well that is good to hear! I didnt mean to imply that.. I was thinking about the sound of other BSS gear Ive used, namely the MIDI gate. very good, solid sound. perhaps better than the more commonplace drawmer 201s. but how is it going to fare in a mastering context across a whole mix? frankly I don't know. but I have a feeling that in a similar, straight boost setting the BSS is going to dissapoint compared to something like a GML eq.

so where can I find an affordable used pair of Pre-harm*n DPR901s?

mike

ebay
where else?

yeah but most people on ebay will not advertise pre or post harmon on those things. I been looking for a deal on a couple of units for a while as they work well and sound good. No deal to my liking yet.

I just bought an old used 901 for 700? and I like it a lot. I use it in my live rack for the lead vocalist in a band I'm touring with. I have only used it twice but I'm deeply in love with it already.

/Anders