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5.25" Internal 5.1 Surround Sound Amplifier

2K views 31 replies 7 participants last post by  schmidtbag 
#1 ·
I am considering giving my home server some extra responsibilities, mostly related to media. I currently have a late 90s 5.1 channel audio system, which is bulky and power-hungry. I generally don't need all of the inputs it has to offer anymore, so I'm beginning to question how much I really still need it. Note that I do not play my audio all that loud, so wattage shouldn't be a big deal. Anyway since my server is always on and in the same room as the speakers, I figured why not have that act as the amplifier. I was thinking of using the 5.25" bay(s) as the place to slot the amplifier.

I've found this to be very difficult to research, possibly because I don't really know the right way to look it up. I know Scythe makes products similar to what I'm looking for, but they usually include a bunch of random crap I don't care about, and they don't support what I do want (like 6 channels).

I would be perfectly ok with buying one that isn't meant to be put in a PC and modify it so it will. Though, I'm not really sure where to look when it comes to finding hardware that will fit inside 3.25x5.75" or 6.5x5.75", and, uses a 12v input.

Any thoughts or suggestions? And yes - if I go through with this, I will upgrade my PSU.
 
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#2 ·
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#4 ·
Right now budget isn't a major factor, but I guess I'd like it to be below $200. I'm not expecting anything very high-power, and SPDIF support is more of a "that would be nice" kind of thing rather than a necessity; I could just have the server process digital signals if I really needed it to (though currently I'm not exactly sure how to get Linux to convert a DD/DTS input signal to be 5.1 analog surround). In other words, I don't expect my needs to be very expensive.

Since I am pretty much just working with analog signals, I could probably get away with 3 separate stereo amplifiers, but I'd rather avoid that if possible.

I'd like to see various options. I've thought about car amps, but as you pointed out, working with 6 channels could be a problem.
 
#5 ·
This is closer. Still too big and overpowered, but getting there:

https://www.amazon.com/gp/aw/d/B01DQYMDBU/

And you could just get a separate external soundcard and hook it up to the internal SPIDF header on your mobo.

Still... You need to ask yourself, is the space really that important? Because an average home-theatre receiver is going to work and sound much better for less money
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#7 ·
Damn that thing is powerful, and like you said, too big to fit. That's otherwise pretty much what I'd expect, though I prefer the dials in the front and all I/O connections in the back.

I'm not an audiophile, and like I said before, I'm not expecting some serious output. My subwoofer, for example, uses some small cheap $20 amp and it still sounds good enough for my needs. I'm well aware this idea will not yield the best results, and arguably worse than what I use now. But consider what my current sound system does now:
* It has several various input sources
* It has a built-in dedicated power source to deliver "clean" electricity
* It has a digital processor for DD/DTS signals
* Can be operated remotely
* It has high-quality amplifiers for a clean audio signal

My PC can be all of those things except the last one. The way I see it, all I need is a better PSU and a well-shielded 6-channel amplifier that fits within the specified dimensions, and then my current surround system is pretty much obsolete. Since I don't intend to play audio loud enough to shake the floors, I shouldn't need any amplifiers that involve beefy transistors and a few pounds worth of heatsinks, so I should be able to use something small enough and not really sacrifice quality.

I'm not sure I understand what you suggest the external sound card is for. The problem is getting the OS to decode a DD/DTS signal. I'm sure it's possible but I haven't really looked into it much yet.

EDIT:
I'll take a closer look at that list a little later. Seems like it might come in handy.
 
#8 ·
The soundcard was just for surround encoding over SPIDF, as they usually come with a license for it. And that's just for cramming 6 channel audio over an SPIDF connection (which only supports 2.0).

Ideally, you'd use something that uses HDMI or USB instead of SPIDF so A: you wouldn't have to encode on Linux (which might be tricky) and B: you don't lose quality from compressing everything to 2 channel DTS.

As for decoding (not encoding) a video file to analog surround, MPV can do that just fine. And if you're using anything other than an MPV based video player on Linux (or one of the front-ends like MPC-QT), I will beat you with a stick
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#9 ·
I think there's a little bit of confusion in terminology here. When I say de/encoding, I'm referring to the way the audio signal is processed over the cable, not from the source file. In order words if I'm watching a 5.1 channel movie, the procedure goes as follow:
1. Decode the movie for the computer to interpret the audio source (which I can currently do just fine). This seems to be what you are referring to.
2. The sound card then has to encode the audio in a compressed signal format that is compliant with DD/DTS (that too I have no problems with).
3. The sound receiver then decodes that signal.

That being said, in the event I get an amplifier that doesn't support SPDIF, the server will have to assume the role of step 3. I am currently not aware of Linux being able to decode a DD/DTS signal from the SPDIF input source, though I don't see why it can't either (since it does support SPDIF input).

Does that make sense? Regardless - this is a separate problem that I'll have to deal with later. Right now my main objective is figuring out what amplifiers to use.
 
#10 ·
#1 depends on the source. All the blu-rays I ripped myself are already DTS encoded, meaning that (ideally) the media player just passes the pure, unadulterated signal to your receiver over SPIDF without encoding/decoding anything. However, if you're playing a game, that's uncompressed 6 channel audio. That's when your soundcard has to encode it for the signal to fit over SPIDF, and again, this is a lossy process.

If you don't have a receiver with spidf, a good linux media player can decode surround audio just fine. You don't have to worry about that.
https://github.com/mpv-player/mpv/issues/1986
 
#11 ·
Yeah, I figured you'd bring up that some movies already have DD/DTS encoding. I realized after I posted my comment that it wasn't the best example. Regardless, it's decoding the inbound signal that I'm concerned about, nothing else. Anyway it's possible I'm the one here who is confused. I got the impression you were bringing up MPV for interpreting the actual media (which I already knew it could do), but are you saying MPV can also be used to read and decode a SPDIF-in source and then output it through the analog output? I figured that's something that Pulseaudio or JACK would be used for.
 
#12 ·
Quote:
Originally Posted by schmidtbag View Post

Yeah, I figured you'd bring up that some movies already have DD/DTS encoding. I realized after I posted my comment that it wasn't the best example. Regardless, it's decoding the inbound signal that I'm concerned about, nothing else. Anyway it's possible I'm the one here who is confused. I got the impression you were bringing up MPV for interpreting the actual media (which I already knew it could do), but are you saying MPV can also be used to read and decode a SPDIF-in source and then output it through the analog output? I figured that's something that Pulseaudio or JACK would be used for.
Yeah I misread the last post too, was about to ninja edit, sorry
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I wasn't even thinking about spidf in. Yeah, theoretically mpv could take a streaming input and decode it, but that seems kinda hacky.

My guess is that something in Linux can use that dcadec library linked above to decode incoming surround, but I don't know anything about that.
 
#13 ·
So after doing my research, I found this:
https://www.amazon.com/6x100W-TDA7498-Class-D-Amplifier-Board/dp/B0073NVLBY/ref=sr_1_41?ie=UTF8&qid=1493214627&sr=8-41&keywords=5.1+channel+amplifier
which ought to fit just fine and seems to suit my needs pretty well. The big problem with it is the minimum voltage is 14v, and it has under-volt protection. I'm not sure I'd want to use a voltage booster.

I haven't found anything else that would either fit inside a PC, supports 6 channels, or doesn't have questionable quality.
 
#14 ·
well.. you couldn't use the PC's 12V rail for amplifier.. believe me, it will sounds awful if not triggering the OCP.

that kit doesn't have digital input. you should wire the analog output to them.
 
#15 ·
Why would it sound awful? A computer PSU is meant to produce a clean voltage for the sake of stability of the rest of the system. Since the board I linked to has a maximum total output of 600W, I certainly don't think I'll be getting anywhere near that in regular use.

I know it doesn't have a digital input but I've come to accept that I'm going to have to deal with that separately.
 
#16 ·
Quote:
Originally Posted by schmidtbag View Post

Why would it sound awful? A computer PSU is meant to produce a clean voltage for the sake of stability of the rest of the system. Since the board I linked to has a maximum total output of 600W, I certainly don't think I'll be getting anywhere near that in regular use.

I know it doesn't have a digital input but I've come to accept that I'm going to have to deal with that separately.
lots of interferences there. I tried once with ATX PSU, they sounds awfully dry and harsh. but if you could live with that, go on. yes, it's only 600W peak. but loading dynamic load to the PC might cause instability.
 
#17 ·
Quote:
Originally Posted by schmidtbag View Post

Why would it sound awful? A computer PSU is meant to produce a clean voltage for the sake of stability of the rest of the system. Since the board I linked to has a maximum total output of 600W, I certainly don't think I'll be getting anywhere near that in regular use.

I know it doesn't have a digital input but I've come to accept that I'm going to have to deal with that separately.
It also shares that 12V rail with some very noisy components. However, like many soundcards, the output could still be acceptable. We've already established that you aren't trying to out-do your old system.

Anyway, ATX PSUs also have a -12V rail on the motherboard header. Wire that as the negative terminal, and you get 24V! However, I have no idea what kind of load they can handle... You should definitely look that up before wiring it that way.
 
#18 ·
Quote:
Originally Posted by brucethemoose View Post

It also shares that 12V rail with some very noisy components. However, like many soundcards, the output could still be acceptable. We've already established that you aren't trying to out-do your old system.

Anyway, ATX PSUs also have a -12V rail on the motherboard header. Wire that as the negative terminal, and you get 24V! However, I have no idea what kind of load they can handle... You should definitely look that up before wiring it that way.
not all ATX PSU has -12v nowadays.. even if they did have, it's not sufficient for an amplifier. worst case, the OCP tripped and shut the system down
 
#19 ·
Quote:
Originally Posted by sakae48 View Post

Quote:
Originally Posted by brucethemoose View Post

It also shares that 12V rail with some very noisy components. However, like many soundcards, the output could still be acceptable. We've already established that you aren't trying to out-do your old system.

Anyway, ATX PSUs also have a -12V rail on the motherboard header. Wire that as the negative terminal, and you get 24V! However, I have no idea what kind of load they can handle... You should definitely look that up before wiring it that way.
not all ATX PSU has -12v nowadays.. even if they did have, it's not sufficient for an amplifier. worst case, the OCP tripped and shut the system down
Yeah, they all seem to be rated for less than 1A. Not nearly enough.

Someone here suggested that you could use 2 PSUs in series:

https://electronics.stackexchange.com/questions/7657/24v-3a-from-atx-power-supply

Meaning that, if you're getting a new PSU anyway, you could re-use your old one (assuming it also fits somewhere inside).
 
#20 ·
Quote:
Originally Posted by brucethemoose View Post

Yeah, they all seem to be rated for less than 1A. Not nearly enough.

Someone here suggested that you could use 2 PSUs in series:

https://electronics.stackexchange.com/questions/7657/24v-3a-from-atx-power-supply

Meaning that, if you're getting a new PSU anyway, you could re-use your old one (assuming it also fits somewhere inside).
yes you could. but the negative side should be lifted from the ground. either way, the PSU won't turn on as it sees a short circuit
 
#21 ·
The -12v (from what I recall, the blue wire) is really only there for legacy purposes, and I think some PSUs actually exclude it entirely. It is otherwise completely useless in modern systems. I think it was meant for ISA slots and such. I personally wouldn't trust utilizing it to reach 24v; I'd be better off using a voltage step-up circuit, and I don't want to do that.
 
#24 ·
I am interested to see what you come up with.

You can get cheap Class D(PWM) amplifiers(high efficiency with decent output wattage when bridged) on the internet, but that lacks any digital inputs, switching and remote capability.

It may be a basis for you DIY box, but powering off the same power supply as the PC can cause noise issues.
 
#26 ·
Well you can pickup cheap 19v PS Bricks designed for laptops for pretty damn cheap.... Cut the end off and wire it into the amp.

Now despite what others have said, you can use the internal PSU just fine if you needed 12v. Any Decent amp will have filters on board, as even the power in your house isn't 100% clean, and no power brick is going to filter it all out. The ability for a PC PSU to handle the load isn't even something to consider, even the weakest PSU's will handle it. Video cards use WAY more amperage. Using the correct gauge of wire will be important though. But again your PSU isn't cut for it, unless you use another device to boost voltage (which really wouldn't be a bad idea. Hell you could even toss in a DC breaker in the loop if you wanted.

Honestly this entire idea of an internal AMP that is 6 channel with no real controller is not a good way to do this. To Balance speaker output in a surround sound environment, you want a preamp designed for this. One that can take DD or DTS and can control output of each speaker to create balance. Plus using old crappy speakers are the last thing you want to do. Best to have a nice set of speakers before looking into a 6 channel amp packed into a 5x5" board. As that isn't going to give you much.

I would atleast get a creative z card to control everything with, atleast that card has some basic speaker balancing options.

I would look into a mini 5.1 receiver.
 
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