series attenuator what's the correct way to wire it up

[skal1]

Hi this a 10k series attenuator and its confusing me I don't want it to be off on the step 1 so were would I put the 100 ohm resistor, should I put it in the input leg or put it between step 1 and step 2 or the ground leg

These are the step's

Step 1, Attenuation = 40 dB, Rx = 9900 ohms, Ry = 100 ohms, Resistor = 100 ohms.
Step 2, Attenuation = 38 dB, Rx = 9874 ohms, Ry = 126 ohms, Resistor = 26 ohms.
Step 3, Attenuation = 36 dB, Rx = 9842 ohms, Ry = 158 ohms, Resistor = 32 ohms.
Step 4, Attenuation = 34 dB, Rx = 9800 ohms, Ry = 200 ohms, Resistor = 42 ohms.
Step 5, Attenuation = 32 dB, Rx = 9749 ohms, Ry = 251 ohms, Resistor = 51 ohms.
Step 6, Attenuation = 30 dB, Rx = 9684 ohms, Ry = 316 ohms, Resistor = 65 ohms.
Step 7, Attenuation = 28 dB, Rx = 9602 ohms, Ry = 398 ohms, Resistor = 82 ohms.
Step 8, Attenuation = 26 dB, Rx = 9499 ohms, Ry = 501 ohms, Resistor = 103 ohms.
Step 9, Attenuation = 24 dB, Rx = 9369 ohms, Ry = 631 ohms, Resistor = 130 ohms.
Step 10, Attenuation = 22 dB, Rx = 9206 ohms, Ry = 794 ohms, Resistor = 163 ohms.
Step 11, Attenuation = 20 dB, Rx = 9000 ohms, Ry = 1000 ohms, Resistor = 206 ohms.
Step 12, Attenuation = 18 dB, Rx = 8741 ohms, Ry = 1259 ohms, Resistor = 259 ohms.
Step 13, Attenuation = 16 dB, Rx = 8415 ohms, Ry = 1585 ohms, Resistor = 326 ohms.
Step 14, Attenuation = 14 dB, Rx = 8005 ohms, Ry = 1995 ohms, Resistor = 410 ohms.
Step 15, Attenuation = 12 dB, Rx = 7488 ohms, Ry = 2512 ohms, Resistor = 517 ohms.
Step 16, Attenuation = 10 dB, Rx = 6838 ohms, Ry = 3162 ohms, Resistor = 650 ohms.
Step 17, Attenuation = 8 dB, Rx = 6019 ohms, Ry = 3981 ohms, Resistor = 819 ohms.
Step 18, Attenuation = 6 dB, Rx = 4988 ohms, Ry = 5012 ohms, Resistor = 1031 ohms.
Step 19, Attenuation = 4 dB, Rx = 3690 ohms, Ry = 6310 ohms, Resistor = 1298 ohms.
Step 20, Attenuation = 2 dB, Rx = 2057 ohms, Ry = 7943 ohms, Resistor = 1633 ohms.
Step 21, Attenuation = 0 dB, Rx = 0 ohms, Ry = 10000 ohms, Resistor = 2057 ohms.

Cheers

Denis

 

[ruffrecords]

It should be between step 1 and 0V. Then the 26R goes between step 1 and step 2 and so on.

Cheers

Ian

 

[skal1]

It should be between step 1 and 0V. Then the 26R goes between step 1 and step 2 and so on.

Cheers

Ian

cheers
Ian

 

[skal1]

ok , I have now wired up pole 1 of the attenuator this is the gain pot which goes from low - high .

pole 2 of the attenuator which is the threshold should be at low threshold when the gain pot is at high.


can I just wire the resistor string the same as pole 1, or do have to reverse the string or can I wire it up like pole1 and switch the ground and input wires?

cheers

Denis

 

[ruffrecords]

Difficult to say. Can you post a full schematic showing how the two poles are wired?

Cheers

Ian

 

[skal1]

as you can see from the circuit diagram 1 pole goes clockwise whilst the other goes anti clocwise,
FAO1O62 attenuator

cheers

Denis

 

[ruffrecords]

I would need more detail on FA01062 in order to say anything sensible.

Cheers

Ian

 

[Hubbub]

Interesting use of FA01062 in that the two sections cancel each other out, sort of. They work together to keep the net path gain constant while clockwise adjustment decreases the signal level into the threshold sensing / gain control stage. Has the effect of raising the compression threshold without affecting the overall gain of the system. The two sections need to be pretty well matched so as to track nicely.

 

[ruffrecords]

The big question is over what range do they operate? 10dB,20dB, 40dB?

Cheers

Ian

 

[Hubbub]

Just looking at the Pye 4060 (and a few other vintage Pye and Pye-like compressors) the threshold control is -24 to +16 dB, for a total of 40 dB range.

 

[skal1]

no more details on that part maybe someone could chime in..

cheers
Denis

 

[ruffrecords]

no more details on that part maybe someone could chime in..

cheers
Denis

There are threads on here about Pye PWM compressors. The information ought to be in one of those.

Cheers

Ian

 

[skal1]

Quote from

Spencerleehorto​

Well im starting to get confused again and need some clarity.
I'm not understanding all the controls.
I first had it wired, 10k input pot, 10k output pot, decay lorlin, ratio lorlin.
Now I have dual gang pot wired one way 10k for input and opposite 10k for output.
I have no threshold control?
Is the threshold control the input/output control?
If so what is the gain control?

cheers

Denis

 

[skal1]

It sounds like the to poles are wire inverse to each other...so when input side of the attenuator is at -24db the gain side would be at +16db , is my thinking correct ..

cheers

Denis

 

[Hubbub]

...Now I have dual gang pot wired one way 10k for input and opposite 10k for output.
I have no threshold control?
Is the threshold control the input/output control?
If so what is the gain control?

To me the mistake is thinking the original design used ganged pots. What it uses was complementary attenuators such that no matter the position the combined attenuation is constant. The value of that attenuation is not obvious to me, but when combined with all the other losses and gains of the design the result is a gain of exactly one. That way you don't need a gain control, the path gain is the same whether you use a straight wire or put the compressor in the path. The EFFECT of ganged complementary attenuators is to change the signal level between the attenuators, where the thresholding detector is picked off. Less input attenuation = more detector drive = lower effective threshold.