Since the code is for a PIC12C509 I had no choice but to use assembly.xplod1236 said:
I think that if you're able to design/find a circuit with 1 unbalanced channel, it should be perfectly possible and quite easy to add as many more as you like. Of course the complexity will be higher, but as long as you look at it like serveral "building blocks" put together, I don't think it will be that much of a problem.paradigm said:I think I'm capable of compreheding many different things, but I strongly feel that programming and putting together the schematics of a balanced multi-channel preamp, unfortunately isn't one of them.
Till agrees with me
.till said:
-UrSv
I've been there, but I'm not sure I found the right attenuator. Lot's of gadgets there, but very little info and specs.
-till
So, if I've got it right I would need 4 pcs of PGA4311 (Four channel version) to make 16 separate channels, in order to get 8 different attenuators for 8 separate amp channels, driving two Quadra-amped loudspeakers?
Could this all be driven and controlled with one set of DRV and INA chips, or does this also have to be doubled?
And on top of all that, comes the icing on the cake,... the task of connecting all these tiny wires and soldering all these tiny little legs on the SOIC's on some adaptors from Brown dog, was it not!?. Pheeeew.
BR
Roland
I've been there, but I'm not sure I found the right attenuator. Lot's of gadgets there, but very little info and specs.
-till
So, if I've got it right I would need 4 pcs of PGA4311 (Four channel version) to make 16 separate channels, in order to get 8 different attenuators for 8 separate amp channels, driving two Quadra-amped loudspeakers?
Could this all be driven and controlled with one set of DRV and INA chips, or does this also have to be doubled?
And on top of all that, comes the icing on the cake,... the task of connecting all these tiny wires and soldering all these tiny little legs on the SOIC's on some adaptors from Brown dog, was it not!?. Pheeeew.
BR
Roland
-Devil_H@ck
Are these "building blocks" then simply daisy chained, like in series or parallelled and does then the output signal of each "building block go to either a "Hot" pin2, or "Cold" pin3 on the xlr's?
Are there some standardized interface and connectors, to make it easier to hook them up to the DRV and INA and what have you not, to make it work?
BR
Roland
Are these "building blocks" then simply daisy chained, like in series or parallelled and does then the output signal of each "building block go to either a "Hot" pin2, or "Cold" pin3 on the xlr's?
Are there some standardized interface and connectors, to make it easier to hook them up to the DRV and INA and what have you not, to make it work?
BR
Roland
you can daisychain them, what provides the possbility to implement individual volume settings for each channel, or parallel them for same setting for all.
The SMD issue is why i would use 2311 or 2310, i can handle them much better. Adapters will provide no advantage here.
Also, as RAP tells, DIP is not that sensitive against microphonics, vibraions, and bending of PCB.
The SMD issue is why i would use 2311 or 2310, i can handle them much better. Adapters will provide no advantage here.
Also, as RAP tells, DIP is not that sensitive against microphonics, vibraions, and bending of PCB.
Oh btw, if you're going to use INA & DRV you won't have a "true" balanced amplifier. It will be: balanced in -> INA -> unbalanced -> volume control -> DRV -> balanced out.
But I don't think that means that it is bad, actually I believe it's pretty difficult to get prefectly equal "hot" & "cold" out with seperate channels for the "hot" & "cold" channel (meaning that the "hot" is identical to the negative of "cold", or the other way around, as you wish). The INA & DRV have very precisely trimmed resistors embeded into them and it would be very hard (if not impossible) to get the important resistors in an unbalanced -> balanced circuit to match up so closely. Also the parts in the circuit part for the "hot" signal and the "cold" signal would have to be exactly the same or they won't be each other's inverted signal anymore.
At least that's what I think, I can always be wrong.
But I don't think that means that it is bad, actually I believe it's pretty difficult to get prefectly equal "hot" & "cold" out with seperate channels for the "hot" & "cold" channel (meaning that the "hot" is identical to the negative of "cold", or the other way around, as you wish). The INA & DRV have very precisely trimmed resistors embeded into them and it would be very hard (if not impossible) to get the important resistors in an unbalanced -> balanced circuit to match up so closely. Also the parts in the circuit part for the "hot" signal and the "cold" signal would have to be exactly the same or they won't be each other's inverted signal anymore.
At least that's what I think, I can always be wrong.
I really don't know what you are trying to do here but I guess you are trying to do a "balanced" design using 2 PGA2310:s with no additional line drivers. Well that is NOT a balanced design.
If you want to know why, have a look at the links I provided at the start of this thread. I explained it briefly in another thread and included some links to articles from Jensen Transfomers.
Same issue here. Just taking the signal, flipping the polarity of it and feed both signals to the cable has NOTHING to do with a differential ("balanced") interconnection.
Well true, but apart from the very simplest circuits with a few active devices you would be hardly pressed to find ANY "true all differential" amplifier. And that includes applications a million times more demanding than audio, MEG or MRI instrumentation for example.
Sorry guys if my tone had a slight bit of edge to it here, but I see this confusion of differential vs single-ended all the time...
Cheers
/Magnus
Arrgh, what am I going to do, what am I going to do
Just as I thought I was on the right track, when I got a few of the the 4311 chips as samples and slowly was beginning to fathm some of the most basic principles on this micro chip thing, I was knocked right back to square one again.
No seriosly, there seems to be much more to this than meets the eyes and there seems to be quite a few different approaches to this balancing act.
Perhaps I should give it up trying to go balanced all the way through the entire system.
It's a pity though, because it appeals to me in many ways.
BR
Roland
Just as I thought I was on the right track, when I got a few of the the 4311 chips as samples and slowly was beginning to fathm some of the most basic principles on this micro chip thing, I was knocked right back to square one again.
No seriosly, there seems to be much more to this than meets the eyes and there seems to be quite a few different approaches to this balancing act.
Perhaps I should give it up trying to go balanced all the way through the entire system.
It's a pity though, because it appeals to me in many ways.
BR
Roland
Roland,
it all isn't that bad! I do also have a pile of the PGA:s and sometime in the future I am going to use them...
I really should spend some time studying for my upcoming exams but...
I'll drop you an e-mail. I really would like to audition your system again, and I am also eager to hear how my new class A amplifier would sound with your 2445:s!
/Magnus
it all isn't that bad! I do also have a pile of the PGA:s and sometime in the future I am going to use them...
I really should spend some time studying for my upcoming exams but...
I'll drop you an e-mail. I really would like to audition your system again, and I am also eager to hear how my new class A amplifier would sound with your 2445:s!
/Magnus
Paradigm, There are a couple of other options, but they are expensive.
You can use two 8 deck attenuators, half the signal goes to each attenuator
Or you could use something like the Goldpt.com shunt attenuator, but ask them not to connect the shunt resistor. Then externally you would have two shunts, each half the size of the original, one on each leg. In retrospect I wish I had bought one of those...
Send goldpoint an email and they will help you design it.
To get the feel of things though I think you could start out doing what I did with a couple of stacked pots and play with some passive designs. It only costs a few pounds/dollars each for those things so you can try a few different designs. The problems and solutions become a lot more obvious as you start to play around a bit
Oh, and I only built a one channel volume control while I was playing! Just enough to get a quick feel for things without spending serious time
You can use two 8 deck attenuators, half the signal goes to each attenuator
Or you could use something like the Goldpt.com shunt attenuator, but ask them not to connect the shunt resistor. Then externally you would have two shunts, each half the size of the original, one on each leg. In retrospect I wish I had bought one of those...
Send goldpoint an email and they will help you design it.
To get the feel of things though I think you could start out doing what I did with a couple of stacked pots and play with some passive designs. It only costs a few pounds/dollars each for those things so you can try a few different designs. The problems and solutions become a lot more obvious as you start to play around a bit
Oh, and I only built a one channel volume control while I was playing! Just enough to get a quick feel for things without spending serious time
Just make the boards yourself, it's quite easy. Really, I can't understand why some people pay $50 (or more, I don't know) for some PCBs when they could make them theirselves for a fraction of that price. Of course self-made PCBs don't have a soldermask and component outlines and they will not be as professional as a factory made one, but I don't think that is a problem for amplifiers, etc.
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