# That 4301 compressor

#### Arjune

Joined Jan 6, 2018
186
I have attached a file of the THAT 4301 compressor. Will the circuit work as the data sheet schematic. I'm confused about the resistors should I ignore the values following the M or K. For instance R14 is 1K43. Is this 1K.

#### Ian0

Joined Aug 7, 2020
5,857
Resistors specified as 1K43, 383k etc. are E96 series. I wish people wouldn't use values outside the E24 series except were absolutely necessary. The circuit works perfectly well if these are rounded to the nearest E24 (or even E12) values,

so use 1.5k for 1k43, 390k for 383k, 5.1k for 4k99, 560k for 590k and works absolutely fine. I've built one.

#### bertus

Joined Apr 5, 2008
22,007
Hello,

As said, the 1K43 is a E96 or E196 series resistor:

Bertus

#### Ian0

Joined Aug 7, 2020
5,857
THAT is telling customers to use the THAT4305 and three op-amps. Profusion has the THAT4305 for £4.19
https://www.profusionplc.com/parts/that4305q16-u
The signal only goes through one of the op-amps, the other two are on the sidechain, so don't need to move very quickly.
You could use an NE5534 and an LM358, and they would only cost 79p and 38p respectively for one-offs.
Profusions's product is more-than-likely real!

#### Ian0

Joined Aug 7, 2020
5,857
Hello,

As said, the 1K43 is a E96 or E196 series resistor:
View attachment 235057

Bertus
My pet hate - designers using E96 values when they are not needed!
Ever looked at a circuit diagram and wondered "why is this 221 ohms? - it must be doing something that requires real accuracy" only to find it's driving an LED.

#### BobTPH

Joined Jun 5, 2013
5,479
That’s because they got a batch of out of spec 121R resistors real cheap.

Bob

#### Papabravo

Joined Feb 24, 2006
18,980
My pet hate - designers using E96 values when they are not needed!
Ever looked at a circuit diagram and wondered "why is this 221 ohms? - it must be doing something that requires real accuracy" only to find it's driving an LED.
That is manifestly not the reason.
At the dawn of the electronics era resistors were commonly 20% or 10%. Over time as the process got better and the manufacturing economies of scale improved 1% resistors actually became less expensive than their cousins with looser tolerances. This process was accelerated by the arrival of SMT processes in the early 1990's. I don't know if a similar transition is taking place to 0.1% resistors. I have been out of the game for a decade and a half. At some point the looser tolerance parts become pure unobtainium. That's the real reason. You did notice that the E6, and E12 series are not even on the list any more.

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#### Ian0

Joined Aug 7, 2020
5,857
That is manifestly not the reason.
At the dawn of the electronics era resistors were commonly 20% or 10%. Over time as the process got better and the manufacturing economies of scale improved 1% resistors actually became less expensive than their cousins with looser tolerances. This process was accelerated by the arrival of SMT processes in the early 1990's. I don't know if a similar transition is taking place to 0.1% resistors. I have been out of the game for a decade and a half. At some point the looser tolerance parts become pure unobtainium. That's the real reason. You did notice that the E6, and E12 series are not even on the list any more.
You have a point!
(But I still have to pay quite a premium for a 0.1% resistor over a 1%, but 1% and 5% are about the same price)

#### Papabravo

Joined Feb 24, 2006
18,980
You have a point!
(But I still have to pay quite a premium for a 0.1% resistor over a 1%, but 1% and 5% are about the same price)
I assume you mean the small quantity retail price as opposed to the intended for production "industrial quantity" buy.

#### KeepItSimpleStupid

Joined Mar 4, 2014
5,088
With "real blue prints", the decimal point tended to no duplicate well and dissapear into the paper. 1K0 is preferable to 1K;

Another thing, you have designations of 5N and 5N5 pure with thins like gasses. 5N is 5 nines or 0.99999%; 5N5 is 0.999995%

Ratios and temperature coefficients are much easier to do in IC form. The resistors are on the same substrate so the temperature coef. is better. laser trimming occurs after encapsulation. The resistors are trimmed through the encapsulation.

5% might be normal manufacturing. 1% standard trimming Lower tolerances might require cooling and multiple passes to get the value right. That's just a guess.

Some capacitors used to be in uuF or micro-micro-Farad. Non-polarized capacitors did have a marking as to where the outer foil is on a capacitor. Now, it's typically not marked. It is especially important in tube designs. The foil needs to go to the low Z point.

#### Ian0

Joined Aug 7, 2020
5,857
I assume you mean the small quantity retail price as opposed to the intended for production "industrial quantity" buy.
Thousand-off reels of 1206 parts.

#### Papabravo

Joined Feb 24, 2006
18,980

#### MisterBill2

Joined Jan 23, 2018
12,700
I do notice that the circuit diagram gives no pin numbers for the IC, and at \$18 each you certainly need to get the connections right the first time. So I hope that you can get some additional information. And it is not at all clear why such precise values are needed in a single channel audio device. Normally circuits would be designed to work with 5% tolerance parts if they woulf be mass produced.

#### Ian0

Joined Aug 7, 2020
5,857
This is the original, from Precision Monolithics Incorporated, back in the 1990s

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#### Papabravo

Joined Feb 24, 2006
18,980
It is perhaps counter intuitive, but it is far easier to make a repeatable precision resistor than a repeatable precision transistor.