"Brickwall" limiter

Hi there...

I've been searching around for a hardware "brickwall" limiter. I'd only want it to start limiting near 0,
Really, I'm thinking of something to substitute real tape saturation. I know there's nothing like it blah, blah. yeah, but I don't want to invest in a nice 24-track and commit to it's maintenance.
So would there be anything to get me to the same ballpark. Especially when tracking drums.

I thought that kind of "brickwall" limiter would do the trick. No controls, no nothing, Just a thing that limits everything over treshold. So i could control the effect with my console outs....

well, is there anything that i could use in this situation...

are you wanting to build one from scratch, or buy one?

have you seen this?
http://rupertneve.com/products/portico-5042/

I have one suggestion:



Got that from here. I used something like this in an INA217 mic preamp going into my computer. It's strictly home-studio quality but not terrible. Here's the way I did it:



I haven't revisited this preamp in a while but I still use it frequently. I think I removed R4 from the circuit, or reduced it substantially. Can't remember. In retrospect I would probably add a pair of diodes, maybe?

Tape does start compressing/saturating far below 0dBWhatever and then softly and gently goes more and more into saturation. A brickwall limiter is the wrong approach to replace a tape machine.

Click to expand...

Yes, I know. I was just trying to get opinions on getting to the same ballpark with something...eh...rackable=)

I'm looking for both routes, buying or making one myself.

That INA34A circuit looks interesting but I'm definitely in for a little bit more..

Neve's stuff is generally great and this "tape saturator" seems like the ticket. But my budget doesn't like it. I'd be wanting at least 4 channels...

how about this:
http://www.tegeler-audio-manufaktur.com/magnetismus2.php

Tape saturaton is non linear. The high frequencies go first. Maybe build a dirty sounding compressor with sloppy time constants and a side chain that is heavily high pass filtered. Might be close enough.

[quote author="Gold"]The high frequencies go first.[/quote]
Note that the diode-circuit given above does address that, there's pre- & de-emphasis.

How well it does that can be another discussion of course.

[quote author="jensenmann"]how about this:
http://www.tegeler-audio-manufaktur.com/magnetismus2.php[/quote]

The Magnetismus 2 was designed with electronic beats in mind. It is supposed to bring back personality and life to Hip-Hop, House, Drum and Bass, Techno, and all the likes.

Click to expand...

Must admit it still feels a bit strange that such a retro-looking box is meant for non-retro styles as mentioned :roll:
It happens more than often with 'promising boxes' like that;
one gets curious how they sound but instead that they're put to the test to some happening human-played tracks,
they're fed some '808'909'-pattern :evil:
... which doesn't tell me much about that specific processor-box then....

I'm not saying that real or simulated bakelite knobs on one hand and 'beats' on the other shouldn't ever meet,
but you'll have guessed by now that I'm more into 'real & organic' stuff myself :wink:

[quote author="clintrubber"]How well it does that can be another discussion of course.[/quote]

What does the pre emphisis? R2/C2 looks like it would remove high end to me. Of course I can't really read a schematic to save my life.

[quote author="jensenmann"]how about this:
http://www.tegeler-audio-manufaktur.com/magnetismus2.php[/quote]

Cool! Michael really stepped his game up from his beginnings on this forum, that looks like a great piece.

-T

[quote author="Gold"]

What does the pre emphisis? R2/C2 looks like it would remove high end to me. Of course I can't really read a schematic to save my life.[/quote]

I agree. Looks like filter->compress->gain->buffer...with the filtering removing the highs to me, but I'm probably wrong

[quote author="Gold"][quote author="clintrubber"]How well it does that can be another discussion of course.[/quote]

What does the pre emphisis? R2/C2 looks like it would remove high end to me. Of course I can't really read a schematic to save my life.[/quote]
R2, R3, C2 do pre-emphasis stuff that is 'undone' by R7, R8, C3 (de-emphasis).

But let's link'n'quote to the source instead of rephrasing:

This circuit is a waveform compressor that compresses more at higher frequencies. It consists of a 70 microsecond (2.25 KHz) pre-emphasis, followed by a diode type waveform compressor, followed by a 70 microsecond de-emphasis.

Click to expand...

http://home3.netcarrier.com/~lxh2/tapesat.html

Bye,

Peter

[quote author="clintrubber"]R2, R3, C2 do pre-emphasis stuff that is 'undone' by R7, R8, C3 (de-emphasis).
[/quote]

So R2,R3,C2 roll off high end but because it's in the negative feedback loop the high frequencies aren't attenuated as much through the op amp?

[quote author="Gold"][quote author="clintrubber"]R2, R3, C2 do pre-emphasis stuff that is 'undone' by R7, R8, C3 (de-emphasis).
[/quote]

So R2,R3,C2 roll off high end but because it's in the negative feedback loop the high frequencies aren't attenuated as much through the op amp?[/quote]

The first stage (the first opamp & stuff) actually boosts the highs: opamp configured as a non-inverting amplifier, so gain (within the frequency limits of the opamp) always 1 or more (so 0dB or more).

But if you attenuate frequencies in the feedbackloop, the opamp 'puts things upside down': it amplifies them.
Lots of stuff to be found about basic amplifiers & filters using opamps, but for now let's try without too much transfer functions.

Look at gain of the first stage for DC & low frequencies: it's 1, since C2 is huge ('high-ohmic') there. For the highest frequencies the cap is a short, so gain is (R3 + R2)/R2, which is more than 1, hence a pre-emphasis as we know it.

Same for the de-emphasis (which isn't in a feedbackloop, hence 'direct' action):
attenuation for DC & low frequencies is nothing, since C3 is 'huge'. For the highest frequencies C3 is a short, so attenuation is R9/(R8+R9).

If all is well, for small signals the diodes don't come into action and the pre- & de-emph. 'undo' each other, so the circuit is not altering the frequency response.

The Mancini-opamp-book (a free pdf) from a certain competitor comes to mind as a nice starting point for opamp-reading.

Enjoy,

Peter

[quote author="clintrubber"]But if you attenuate frequencies in the feedbackloop, the opamp 'puts things upside down': it amplifies them.
[/quote]

That's what I was getting at. Thanks for the detailed explanation.