THAT4301 compressor

[hazel]

I think it´s a misunderstanding. I´m talking about the other drawings D1 sorry : that is connected to the 2nd switch pole of the knee switch...the rest looks fine to me.

Haha don't worry!

This is the kind of things that happens when using different schematics

You are referring to this part of the Hard/Soft Knee switch, i already connected, tested and worked

 

[druu]

Anybody know how to alter the threshold and gain range?

 

[hazel]

Anybody know how to alter the threshold and gain range?

What do you want to alter on threshold and ratio?

If you want to "limit" ratio or threshold you can alter pot value. 10k lin pot ratio goes from 1:1 to inf:1 and half rotation measures 4:1 = 5k ohm. Same applies for threshold pot.

You can customize it by building a rotary switch.

 

[druu]

I just wanted to bump this thread in the hopes to keep things alive..

 

[hazel]

Hi Druu,

I've just finished front panel design and i'll start assembly ASAP.

THAT4301 works like a charm, very versatile, from dirt to clean with DRY/WET control.

HPF sidechain is also a very useful feature. LPF too, very subtle but useful.

I must say i didn't used ungifted PCB but a THAT Demo Board.

Stay tuned for pics!

 

[druu]

Nice! Can you tell us where you inserted the HPF sidechain filter? I'd like to add this to my build, possibly with adjustable frequency selection.

Also can someone suggest ideal value pots for a mastering build? I think 5K ratio would be fine but threshold and gain I'm unsure if 50K or 100K would be better. Obviously I'll be making these three controls stepped rotaries.

 

[hazel]

I inserted sidechain filters just before the RMS detector.

Opamp buffer and a batch of resistors and caps with 2 rotary switches, 6 poles for HPF and LPF.

Don't know about pots, i used 10k, same as THAT 4301 Demo Board i got

 

[abbey road d enfer]

Nice! Can you tell us where you inserted the HPF sidechain filter? I'd like to add this to my build, possibly with adjustable frequency selection.

Also can someone suggest ideal value pots for a mastering build? I think 5K ratio would be fine but threshold and gain I'm unsure if 50K or 100K would be better. Obviously I'll be making these three controls stepped rotaries.

There is no difference between 50k and 100k there, because they drive a very high load; they could be anything between 20 and 250k. Less than 20 and the dissipation would be excessive, more than 250k and the influence of the load could change the control law. In between, there is not a "better" choice, just a matter of convenience.
In fact the 5k could also be changed for e.g. 10k, but that would imply modifying some surreounding values (R19, 20 & 27). That would not be a better or worse choice, just a different one.

 

[Nescafe]

I just found THAT dn115 is updated, now using J113 instead of obsolete 2SK170.

 

[druu]

Thanks abbey, is was more trying to get guidance on what the different values would do for the range of each control, how it would affect the control and which value would be more suitable for a smaller range for mastering.

 

[abbey road d enfer]

Thanks abbey, is was more trying to get guidance on what the different values would do for the range of each control, how it would affect the control and which value would be more suitable for a smaller range for mastering.

Smaller range comes by altering other components. R22 for Threshold, R19 for Ratio and R25 for Gain. Pot value doesn't do much within certain limits.

 

[hazel]

is was more trying to get guidance on what the different values would do for the range of each control, how it would affect the control and which value would be more suitable for a smaller range for mastering.

This is a very versatile compressor, i'm using stock values and behaviour changes from clean to very noticeable effect. Can be used as mastering-glue compressor and 2buss insertion.

If you are concerned about values i'd calculate ratio pot rotation resistance and make a rotary switch with ratios 1,1:1 1,5:1 1,8:1....any value you want using resistors...same applies on threshold and gain.

 

[shot]

Is there a way to modify attack & release ranges in the schematic provided in DN115 note?

I've built very similar circuit based on the Pic* comp AR and it's range is very limited. Is there a way to have shorter/longer attack or release by changing some values (R72,R73...C18... maybe)?



Luka

 

[beatnik]

nice thread

i am looking to build a limiter for mastering

anyone tried the 4301 circuit in this application ?

i need something at the end of the chain to grab 1 or 2 db before the converters

most people suggest to use plugins but i would really like something analog

 

[abbey road d enfer]

nice thread

i am looking to build a limiter for mastering

anyone tried the 4301 circuit in this application ?

4301 offers a level of performance that is roughly comparable to a 2252/2180 combo. If the 3dB noise and slightly higher THD are acceptable for you, why not? But if you want the best performance without exotic arrangements, you may use the 4301's RMS detector in conjunction with a 2180B. Many limiter designers have considered that that level of performance is not adequate and have used very sophisticated attack/release circuits (A/R circuits are the main cause of THD in a compressor) and paralleled multiple VCA's in order to improve noise performance.

i need something at the end of the chain to grab 1 or 2 db before the converters

most people suggest to use plugins but i would really like something analog

I don't know how you could make a plug-in limiter to operate before conversion...

 

[hazel]

nice thread

i am looking to build a limiter for mastering

anyone tried the 4301 circuit in this application ?

i need something at the end of the chain to grab 1 or 2 db before the converters

most people suggest to use plugins but i would really like something analog

As abbey said 4301 IC is not the most useful limiter, it's a wonderful RMS compressor and can act as a fast compressor but not a limiter...

You can build a GSSL and use very fast attack, auto release and 10:1 ratio. Easy build and plenty of info and mods.

I use SSL comp plugin as limiter and works pretty well

 

[abbey road d enfer]

I use SSL comp plugin as limiter and works pretty well

But you use it AFTER conversion, don't you? That means you have to manage strategically the peaks, probably by recording at about -12dBfs peak, which is a commonly accepted method. That may be in conjunction with some hardware compressor.
I think beatnick wants to use some kind of brickwall limiter before conversion, in order to...what? probably with the elusive goal to use all the 24 bits in his converters...I don't know, just guessing here.
There have been attempts at that type of limiters, when converters had a much lower resolution; the EMT266, which had been designed as a transmitter-protection broadcast limiter, has been used in this capacity.
All that became obsolete when converters became capable of giving valid 16-bit conversion with 20+ dB headroom.

 

[hazel]

I use SSL comp plugin as limiter and works pretty well

But you use it AFTER conversion, don't you? That means you have to manage strategically the peaks, probably by recording at about -12dBfs peak, which is a commonly accepted method. That may be in conjunction with some hardware compressor.
I think beatnick wants to use some kind of brickwall limiter before conversion, in order to...what? probably with the elusive goal to use all the 24 bits in his converters...I don't know, just guessing here.
There have been attempts at that type of limiters, when converters had a much lower resolution; the EMT266, which had been designed as a transmitter-protection broadcast limiter, has been used in this capacity.
All that became obsolete when converters became capable of giving valid 16-bit conversion with 20+ dB headroom.

obviously know that a plugin is after conversion, I was just trying to point that GSSL is very good at catching fast transients

 

[darkus]

hazel

Did you ever finish this build?

I just purchased two pcbs and gonna start working on this soon. Im hoping this simple comp will give me that dbx160xt sound. Ive listened to your clips and i hear this compressor is distorting pretty fast?

 

[hazel]

hazel

Did you ever finish this build?

I just purchased two pcbs and gonna start working on this soon. Im hoping this simple comp will give me that dbx160xt sound. Ive listened to your clips and i hear this compressor is distorting pretty fast?

Hi Darkus!

Compressor is finished and working but i'm designing front panel.

Samples in my Soundcloud are an example of Time Constant Capacitor values at THAT4301 pin 5.

10uF cap for RMS behavior and change them to taste for some distorted sound, i personally use crushed sound with blend control for parallel compression and RMS with SOFT KNEE for insert use.

This compressor doesn't only distorts, this compressor doesn't only sounds smooth and transparent...it does both things!

You can just build it using stock values or mod it to your taste, there's plenty of info in this thread (HPF SC, manual Attack and Release, HARD/SOFT knee, etc)

Regards,

Joan