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| Just how bad is it? Audio mixer with headphone amp. |
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| BrianHG:
--- Quote from: paulca on February 25, 2018, 05:19:25 pm ---I'm borrowing from the design of pro-audio mixing desks. I found it a little odd that I was hearing two different things from two different places. Yes the original might have worked fine and no I probably wouldn't notice the difference, but I have at least a small part of my background and family working in pro-audio. Things are done differently. An example was pre-amp gain. Everything audio I know prior to electronics told me to add gain at the input. But all the amatuer audio stuff in EE forums use pots on the input to attenuate then boost which is a pointless noise generator circuit. A the same time I still need you guys to help me as borrowing blocks from a book can lead to trouble until I learn the details of how to calculate my way out of a pickle. Out of interest, if you put all the blocks together from the book and built a 24 channel desk with full inserts, parametric EQ, sends, returns, channel groups, PFLs, AFLs etc. etc. it would probably have in the order of 500-1000 op amps. Do your CDs sound distorted or noisy? --- End quote --- No longer, everything today is all digital. But, back to older analog. You need to count the op-amps through 1 source to the central mixing point. Then that mixing point point to the output jacks. And yes, after all that, there is some loss and change in sound & the EQs had bypass buttons on the better units consoles for true flat. Remember, they take all the sources & they only want to go through that mixing console once. Take that output and pass it through another mixing console, and the sound will be affected. I'm not saying these consoles were junk, far from it, but, there is a reason we have gone all digital today. Pass a digital out from 1 digital mixing console into the next digital mixing console and remix with flat EQ settings and I bet the sound will go through perfectly clean if the code was written properly. |
| paulca:
I think we agree, however do not be fooled into thinking that "everything is digital today". In the past few years I have probably seen about 20 mixing desks in person, I have yet to see a digital one (that wasn't a PC or Mac based thing). Small 8 to 16 channel mixing desks you would use as an audio semi-pro running a few gigs and recording a few demo tapes would be like buying a higher grade oscilloscope. Priced, today, around £1000. A fully digital mixer would cost about ten times that. PC and Mac based solutions are plagued with problems, not least the thing rebooting or installing updates live on stage, but they are used. Very often you would have multiple programs producing audio on a single laptop, these would be mixed digitally with an external remote pyhsical control unit, but the sum output of those will end up going through an analogue mixing desk. If you are going to a pro-audio studio and want a fully digital desk, expect to pay £500 a hour+. |
| BrianHG:
--- Quote from: paulca on February 25, 2018, 05:36:15 pm ---As someone on here said, if an audiophool spends £400 on a set of speaker cables it WILL sound better to him. --- End quote --- I spent 300$ CDN (around 250$us) on my 10 feet speaker cables 100% pure silver and measured them to copper with my scope. Mixing a 40hz sine wave with a smaller 10Khz square wave. With the thick solid core copper, the peaks on the 40hz squished the squareness and amplitude of the smaller 10Khz signal inside. The silver cable were almost perfect, though, I could not head the difference. I still prefer that the signal out of my amp is reaching the speaker where a high current low frequency isn't mushing the fidelity above 10Khz. |
| BrianHG:
--- Quote from: paulca on February 25, 2018, 05:29:33 pm --- --- Quote from: BrianHG on February 25, 2018, 05:13:46 pm ---As for driving headphones, I stand by my earlier suggestion of using 1 op-amp, driving a 2N3904/6 emitter-follower setup. Too many op-amps will kill sound fidelity. --- End quote --- This is the books suggestion for a cheap, simple headphone amp: --- End quote --- Yes, that's the basic design and you will get a whole lot more mileage out of that circuit instead of parallel op-amps.... In fact, that circuit will ROAST the parallel opamps... Just double C1 (if you keep the 10k load) and C2. Make C2 a low ESR cap. Only take it that far if you have 20hz headphones or are using my Subwoff... |
| paulca:
--- Quote from: BrianHG on February 25, 2018, 05:48:30 pm ---Yes, that's the basic design and you will get a whole lot more mileage out of that circuit instead of parallel op-amps.... In fact, that circuit will ROAST the parallel opamps... --- End quote --- I do hate safety nanny limiting and ... the 5532 has a current limiter. I know I like my headphones and they are the most expensive I have owned, but they have too easy a life. I haven't heard them clip or distort very often. Too soft. So... adding in the real point of all this is to learn and to play with electronics.... maybe I should do a transistor output stage for the experience. It can't been anywhere near as frustrating as debugging opamp circuits.... oh wait. It probably can. |
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