THAT4316 Battery-Powered One Knob Squeezer Guitar Compressor

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mediatechnology
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THAT4316 Battery-Powered One Knob Squeezer Guitar Compressor

Post by mediatechnology » Thu Nov 21, 2013 5:59 pm

This is a preview of a Battery-Powered One Knob Squeezer Guitar Compressor using the new THAT4316 low-voltage, low current Analog Engine®.

The whole gizmo is powered from a single 9V battery and pulls about 5 mA.
The Design Note with circuit description is here: http://www.waynekirkwood.com/images/pdf ... ressor.pdf

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Battery-Powered One Knob Squeezer Guitar Compressor Using the THAT4316 Analog Engine

The prototype

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THAT4316-based One Knob Squeezer Prototype

The THAT4316 has excellent VCA THD performance as seen from this FFT:

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THAT4316 One Knob Squeezer -20dBu 1kHz VCA Distortion

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mediatechnology
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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by mediatechnology » Sat Nov 23, 2013 9:57 am

Thanks Roger.

To my ear the NLC was better particularly on Bass.
I did some LF FFTs with 1u and 2u2 in the NLC and the 2u2 seemed better all-around.
I'm not a guitar player though but several people at THAT are and they seemed to like the NLC's tuning.
The NLC/No NLC area is ripe for experimentation.

BTW I found the 4316 incredibly easy to use.
It doesn't get much simpler and I was surprised at the level of performance for a 5V (or less) single-supply part.

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mediatechnology
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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by mediatechnology » Fri Nov 29, 2013 9:21 am

Yep SMT only.
The SMT-DIP adapters THAT sell for these and their other SMT parts make prototyping easy.
http://www.thatcorp.com/Adapter_Boards.shtml

I have to say that the THAT4316 is an extremely easy part to apply. The VCA is amazing for such a low-voltage part.

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JR.
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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by JR. » Thu Dec 05, 2013 8:53 pm

Nice job... a "clean" guitar compressor may be moving a little in the wrong direction for lead guitar, but clean compression should be appreciated by bass players. That part would be sweet to make a compander for say a battery powered wireless microphone where the good battery life would be nice, or in an analog chorus/delay guitar pedal, also battery powered.

SMD is inevitable....resistance is futile (and very tiny).

JR

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mediatechnology
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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by mediatechnology » Thu Dec 05, 2013 9:56 pm

Thanks JR.

I have a dirty compressor but it's top secret.

THAT have some pretty good Compander designs for wireless apps in the datasheet.
Even with a fully DSP-based mic it would seem to have a niche to prevent mic A/D overload as a protection limiter.

Another potential configuration is a analog encode/DSP decode wireless compander that would reduce MIPS, latency and power on the encode side.
On the decode side you've got power to burn but on encode low power is still critical.

In ear monitoring is another good battery-powered decode application.
In ear requires very low latency.

I too had thought about it for BBD delay/chorus to replace NE570 designs.

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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by mediatechnology » Sat Dec 07, 2013 11:13 am

One thing I should point out to anyone contemplating the use of the 4316 is that, with the exception of the RMS detector output it is current in/current out.

I write this due to to a thread I found here: http://www.madbeanpedals.com/forum/inde ... ic=12634.0
A bit concerned that it's a 5V chip.
and
Probably because 5v is more than sufficient for its stated purposes, none of which are guitar pickups.
Let me clear up this bit of confusion...

The supply voltage of 5V (max) of the 4316 doesn't limit it's overload capability to <5V because the VCA inputs/outputs and RMS detector input are currents, not voltages.
The resistors which convert the input and output currents to voltages can be scaled for use at elevated levels which exceed the 5V supply of the part.
The RMS detector output is not constrained by supply voltage since it scales at ~6mV/dB or ~120mV/20dB around a mid-supply value of +2.5V.
With input/output resistors scaled properly and a supply voltage to support the final output stage I-V converter's signal swing, the part can be used at pro levels of +21 dBu or more.

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JR.
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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by JR. » Sat Dec 07, 2013 3:24 pm

Doh... :lol:

Yup their (current ratioing) VCAs are current-in current-out devices too, as long as they don't support voltage output with built in opamps.

I have run into process/voltage limitations with some modern analog or mixed technology ICs. A sweet (TI) class D chip I use to drive the speakers in my battery powered drum tuner, that sips current, can not tolerate the full unloaded voltage from 4x AA cells when fresh (1.65V ea). I had to add a little pre-regulator.

Perhaps in a future generation I will just use rechargeable AA cells that are only 1.3V or so when charged, or only 3x AA cells.

JR

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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by pascal.verdet » Mon Jan 20, 2014 9:44 am

Hi Wayne,
Nice work. How do you get FFT ?

Cheers,
Pascal

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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compre

Post by mediatechnology » Mon Jan 20, 2014 9:56 am

Thanks Pascal.

Those screen captures are Visual Analyzer: http://www.sillanumsoft.org

I also use Audio Tester http://www.audiotester.de

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Re: THAT4316 Battery-Powered One Knob Squeezer Guitar Compressor

Post by hazmo » Wed Jul 18, 2018 10:51 am

Image Image


I designed and ordered the pcbs already quite a while ago, but only recently got around to building it. It's a great and neutral sounding compressor! It works really well for me in almost any setting. With clean sounds for non-invasive dynamic reduction as well as distorted sounds for long and standing tones. So thanks!

But I have a couple of questions if you don't mind. What was your reasoning behind choosing the 4316 over the 4315? The website states +-60dB gain range for the 4315 vs. +-50dB for the 4316. In the datasheet for the 4315 it says +-50dB though. Do you know which is right? I'm asking because I'm wondering which part to use for a gating circuit. Would you consider 50/60dB "off enough" or would you rather recommend the 4320 with -100dB range? Since noise already should be a fair bit lower in level compared to the signal I would think it should suffice. The datasheet advises to keep the EC pins within 0,5V of VCC/2, 60dB would be 0,36V of control voltage. Could it possibly be driven further for higher attenuation? Rising distortion or non-linear gain law wouldn't be an issue for my application.


Thanks, Volker

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