Search found 3705 matches

by JR.
Sun Oct 02, 2011 10:14 am
Forum: Pro Audio Design
Topic: Balanced Inputs
Replies: 89
Views: 155060

Re: Evolution and Origin of the SuperBal Variable Gain Input

OK, if you are asking about sum buses, this I have spent some time thinking about. First there is a critical distinction between I/O and sum buses... I/O generally, (not always on the "O" side) only interface between two local grounds. Summing a multiplicity of signals requires dealing wit...
by JR.
Sat Oct 01, 2011 11:19 am
Forum: Pro Audio Design
Topic: Balanced Inputs
Replies: 89
Views: 155060

Re: Evolution and Origin of the SuperBal Variable Gain Input

Would this basic topology make a good current-domain mix amp? Looks like too many spare parts for a mix amp, but interesting. The topology makes the + input look like virtual earth for common mode currents coming into both inputs, while + input is high impedance for normal inputs. it will also canc...
by JR.
Sat Oct 01, 2011 10:40 am
Forum: The Peabody Lounge
Topic: Jim Williams and Bob Pease, RIP
Replies: 5
Views: 10592

Re: Jim Williams and Bob Pease, RIP

I've got a note from Jim in a file somewhere, that he sent in response to my complaint about one of his "ideas" published where he was using CMOS gates as linear amplifier stages. This technique mostly works as long as all you want is a modest loop gain inverter, but I pointed out the nast...
by JR.
Fri Sep 30, 2011 6:03 pm
Forum: Pro Audio Design
Topic: Balanced Inputs
Replies: 89
Views: 155060

Re: Evolution and Origin of the SuperBal Variable Gain Input

It's not a crazy design target to desire zero net current between chassis (like transformers), so it's of interest....... but as you know there are so many flavors of quasi pro interfaces that you always have to be careful of what you might encounter that could trip up the best laid plans. On thing ...
by JR.
Fri Sep 30, 2011 4:39 pm
Forum: Pro Audio Design
Topic: Balanced Inputs
Replies: 89
Views: 155060

Re: Evolution and Origin of the SuperBal Variable Gain Input

maybe you can find somebody you can send that stuff to... :D

JR
by JR.
Fri Sep 30, 2011 2:26 pm
Forum: Pro Audio Design
Topic: Balanced Inputs
Replies: 89
Views: 155060

Re: Evolution and Origin of the SuperBal Variable Gain Input

I guess I'm a little cranky today (every day?). Yes an instrumentation amp has a differential input, so cross connected instrumentation amps are literally cross connected differentials, but there is no practical benefit to this topology other than selling more ICs for the app writer's employer. Nobo...
by JR.
Fri Sep 30, 2011 10:26 am
Forum: Pro Audio Design
Topic: Balanced Inputs
Replies: 89
Views: 155060

Re: Evolution and Origin of the SuperBal Variable Gain Input

lets see a 3 opamp inst amp inside each package... 9 opamps total... pass....

Paralleling two actual "instrumentation" amps seems horribly redundant.

I started out reading ideas for design to absorb input, but after a while I became more critical.

JR
by JR.
Thu Sep 29, 2011 10:33 am
Forum: The Peabody Lounge
Topic: have you hugged your computer today?
Replies: 3
Views: 7330

Re: have you hugged your computer today?

Express PCB comes pretty close. I've never had to contact a human there. Have you downloaded a Chinese character set? Glad everything fit. I don't plan to learn Chinese or japanese, but I have long been worried that the operating systems for newer generation microprocessors might be in other than e...
by JR.
Wed Sep 28, 2011 3:17 pm
Forum: The Peabody Lounge
Topic: have you hugged your computer today?
Replies: 3
Views: 7330

have you hugged your computer today?

I can't help reflecting upon how good we have it compared to the bad old (pre cheap computer power) days. I just got in a shipment of bottom metal (made in TX) for my new generation product design and it fits perfectly into my injection molded plastic clamshell (made in TX but tooled in China, that ...
by JR.
Tue Sep 27, 2011 5:16 pm
Forum: Pro Audio Design
Topic: Balanced Inputs
Replies: 89
Views: 155060

Re: Evolution and Origin of the SuperBal Variable Gain Input

That looks pretty good, I recall back in the '70s when a simple opamp couldn't pass a clean square wave... times change for the better.

JR