Input and output attenuators

[johnheath]

Hi all…

I am looking for a input and output attenuator like the ones in the UA176.

It is for a vary-mu clone that I am fiddling with and since I am using a 10k:10k input transformer I guess that the input attenuator should be 10k as well?

The output is 600R so a 600R attenuator should be fine.

Or… Is there a way to create these from lets say a dual potentiometer and couple of resistors?

If possible it would be best if they could be ordered from somewhere within the EU.

Low cost is also preferable


Thanks in advance

/John

 

[lassoharp]

It is for a vary-mu clone that I am fiddling with and since I am using a 10k:10k input transformer I guess that the input attenuator should be 10k as well?

  10K is just providing a bridging impedance for any typical low Z source.  Most constant impedance attenuators are 500/600 ohm.  The one Hairball Audio sells for the 1176 will work great for input and output.

You can make them on a rotary switch.  NY Dave had a couple schematics on file for a Ladder and Bridged T type at one point.  I'm not sure if they're still up but someone may have them downloaded, or have their own version.

The alternative for the output is to use either a 600 ohm or 1K pot.  This may or may not create issues with response and distortion due to the slight variations in impedance.  Many times you can't even tell

 

[johnheath]

Thank you sir and sorry for the late answer but I was fiddling to create a attenuator based on the tutorial below… it turned out to create  distortion.

http://www.electronics-tutorials.ws/attenuators/bridged-t-attenuator.html

I can see in the "Gates Sta-Level" schematic that they use a balanced H-pad but I would like it to be adjustable in a wider range.


I could calculate a stepped attenuator but I would like it to be a pot and being able to have "input" and a "output" pots…

Best regards

/John

 

[johnheath]

Forgot this one:

 

[PRR]

> fiddling to create a attenuator … it turned out to create  distortion.

A resistor attenuator won't distort.

Large loss or an unfortunate impedance WILL cause the thing which drives it to distort.

 

[johnheath]

Thank you sir

In this case I plugged an acoustic guitar into a transformer based DI-box to a tube mic preamp to the limiter and the attenuator was coupled at the output of the limiter… and the final step was an active monitor.

According to the tutorial with the bridged T-pad…. based on the calculations I used a 5k dual pot with two 560R resistors what I had in hand)… maybe I missed something  but I was doing it 2:00 am so I was a bit too tired too focus.

I'll do further tests on this matter


Best regards

/John