THAT4301 compressor

[Humner]

Here's mine, working like a charm!

Very awesome. design/colors is spot on.

can you share how you did your Wet/dry control? probably could also implement a bypass along with the wet/dry circuit.

 

[Humner]

Thanks for that. I've ordered a board to play around with. I had an idea to have separate dry and wet control summing into an opamp, similar to crush n blend.

 

[Humner]

what does the gain control do? is that make up gain?



nevermind - I read through the design notes and found that is exactly what it is.  ;D

 

[Diydiy]

Hi again

Earlier (thread page 12) I wrote about a distortion problem. I used mine as an  electric guitar compressor.  The compressor was without the optional input stage and my guitar was directly plugged into the compressor. And that gave distorted audible harmonics in peak mode. Well, later I noticed, that when I used an effects pedal (delay) before the compressor, there was no audible distortion anymore. The reason was not the input level. It seems, that the compressor really needs some sort of buffer or low impedance output stage BEFORE the compressor. At least an electric guitar seems to give a side effect (audible distorted harmonics), if no input stage or buffer is used.

 

[Humner]

Has anyone tried a stereo version?

Does anyone know which controls are linked when in stereo?

 

[Humner]

What is the phase after going through this compressor? The 3rd opamp(OAG$3) on the output is inverting - so is it correcting a phase inversion which is occurring before this opamp? maybe from opamp 1(OAG$1)?

Has anyone attempted to inject a dry signal at pin 13? could this work without a resistor between the VCA output and the 3rd built in opamp as they are directly coupled?

 

[abbey road d enfer]

What is the phase after going through this compressor? The 3rd opamp(OAG$3) on the output is inverting - so is it correcting a phase inversion which is occurring before this opamp? maybe from opamp 1(OAG$1)?

The gain-cell is actually inverting current, so the overall polarity (not phase) is positive.

Has anyone attempted to inject a dry signal at pin 13?

Pin 13 is a current node; it is indeed possible to inject a signal there, but I don't see what you expect. The signal should be a current, not a voltage.

could this work without a resistor between the VCA output and the 3rd built in opamp as they are directly coupled?

I don't know what you are referring to, but the VCA output and the input of OA3 are internally connected; how more directly could that be?

 

[Humner]

Thanks for responding. I should have prefaced my post with "I have some potentially stupid questions"

I'm looking into designing my own circuit to provide a wet/dry control and thought it could be implemented using what was already available from the circuit.

I understand there are several ways to do it, the way I had envisioned was to use a inverting buffer to mix the wet and dry signal, however as there is already one in-place(the 3rd opamp inside the that4301 package) I thought I might be able to utilize it in some way to achieve the same result.

 

[abbey road d enfer]

Thanks for responding. I should have prefaced my post with "I have some potentially stupid questions"

I'm looking into designing my own circuit to provide a wet/dry control and thought it could be implemented using what was already available from the circuit.

I understand there are several ways to do it, the way I had envisioned was to use a inverting buffer to mix the wet and dry signal, however as there is already one in-place(the 3rd opamp inside the that4301 package) I thought I might be able to utilize it in some way to achieve the same result.

That won't be easy. I think the best solution is using a pot between the input and output; because the impedance will be variable and certainly not adequate for proper interfacing, you will need a buffer. Fortunately such a buffer, at unity-gain is easy to add.

 

[Jitter]

I wanna build a stereo compressor link two PCB of 1.6V (New version).
Work fine this option of AR in the new PCB 1.6?
What is the new pinout for stereo link?

 

[Jitter]

UP!!

 

[abbey road d enfer]

UP!!

I hav etried to find the schemo for v. 1.6; couldn't.
In order to create a proper Stereo Link, you would need to insert an analog OR between pin 7 of OAG$2 (control voltage output) and pin 15 of the VCA (Ec+).

There are other strategies possible. The simplest is to join the RMS detectors pins 5 from both sides. Ideally, you should disconnect one set of capacitors C7/C9, in order to have only one at a time. The biggest issue is that the switches must be in the same position (Hard/Soft and Peak/RMS) and all controls, threshold, gain, and ratio must be exactly matched; this is difficult because of the poor tolerance of potentiometers.
Alternatively, you could join the RMS detectors and use only one side chain. Both VAC's would be driven from the same side-chain.

 

[Jitter]

There are the docs of 1.6V Pcb http://diy-tubes.com/image/data/manuals/That4301-v1.6-full.pdf

 

[abbey road d enfer]

There are the docs of 1.6V Pcb http://diy-tubes.com/image/data/manuals/That4301-v1.6-full.pdf

OK. It doesn't change any of my comments.

 

[Jitter]

So, the AR board is correct and will work fine?

 

[ungifted]

Hi Jitter, sorry for late answer. Please note that the AR is NOT tested. I wasn't succeed with AR, no time at all for working it out.

 

[Jitter]

As there are no exist specifications on the link connector of AR pcb... what would be the correct pinout to connect the AR board with PCB 1.6v? Would you be connected to pins of 4301 chip?

Regards

 

[ungifted]

Just take a look at schematics, all info is there.
1.6 is the same pcb with minor changes in layout, some nominals etc.

 

[Jitter]

Ok. Thanks for your responses.

 

[Jitter]

Hi friends.
I decided  implement the mod of the SC RMS.
I have a question. If I put the condenser group for variable RMS  on the PCB Master...
C7 and C9 should be annulled on the master pcb?. Must put a link con the posición of C7&C9?
It's correct this option for the mod of variable RMS?
See the .jpg

Regards