Simple 600 ohm test load

[mutterd]

ahhh…

i get it - its the shunt in the first circuit that makes the pad but maintains the 600R load as seen from the output…

right, I'm a moron - i had it in my head that it was 600R one way and then 600R + a 20dB pad the other way…

but i see what is happening now…

in the up position there is a 600R shunt, in the down position there is 270R series resistors and a 60R shunt - 600R each way.

humbled again - thanks for explaining it…

 

[joaquins]

ahhh…

i get it - its the shunt in the first circuit that makes the pad but maintains the 600R load as seen from the output…

right, I'm a moron - i had it in my head that it was 600R one way and then 600R + a 20dB pad the other way…

but i see what is happening now…

in the up position there is a 600R shunt, in the down position there is 270R series resistors and a 60R shunt - 600R each way.

humbled again - thanks for explaining it…

You are not a moron, this isn't about humbling anyone... We all speak crap once in a while. Good thing is you get it now, and this is what's all about.

Regards,
JS

 

[ruffrecords]

You are not a moron, this isn't about humbling anyone... We all speak crap once in a while. Good thing is you get it now, and this is what's all about.

Regards,
JS

+1

I designed the thing and it took several weeks before PRR pointed out the obvious flaw. You learned something from this, therefore, by definition, you are not a moron.

Cheers

Ian

 

[Gavin Pursinger]

Thx Ian...this does not really look like an H pad...could I use this on my new limiter build INSTEAD of the store bought 20 db pad for any additional benefit ?...thx

 

[user 37518]

Thx Ian...this does not really look like an H pad...could I use this on my new limiter build INSTEAD of the store bought 20 db pad for any additional benefit ?...thx

If the limiter has a typical 10K input impedance (or considerably large, like, say, over 1K), this should work perfectly.

 

[ruffrecords]

Looking back to the start of this thread I see I designed this back in 2006. The error in the circuit seems obvious to me now (pin1 goes to pin 1 and nowhere else) but I still have and use the original design in a tiny die-cast box with an XLR output and with its input XLR on a flying lead.

It definitely is not an H pad, it is a U pad. An H pad can be designed to have identical input and output impedances but if you are connecting to a 10K bridging input this is no longer necessary and the simpler U pad will do exactly what you need.

Cheers

Ian