Recommendations for a linux PC-based sound system

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Recommendations for a linux PC-based sound system - on a budget for a

2011-12-13 18:17:44

Hello HydrogenAudio forumers. I need your wisdom to improve my sound system for music and movies from my linux machine. I'm essentially a n00b when it comes to sound quality. I am aware there is a similar thread on this forum, but I think my questions a bit different.

The past several years I've been in uni living in tiny rooms, and I've used my computer (onboard sound card) + logitech Z 4 speakers. Now that I'm a bit more grownup, I'd like a bit more grownup sound system. I don't want to spend more than 300gbp (plus a bit more for a sound card or USB DAC) I mostly just listen to music (occasionally a bit loud - dance parties with myself. I use lossless FLAC as much as possible, but do have a quite a few files stuck in lossy mp3s) but occasionally for films, too.

I gather that it's better to get an amp/receiver and a good set of speakers rather than a PC speaker system, so I'm looking to put together a 2.0 sound system and route my computer audio through the receiver. Any recommendations on equipment in this price range? There's all sorts of specs I don't understand - amplifier power output, amp. frequency response, amp. max. power consumption, speaker sensitivity, speaker freq. response, speaker nominal imedance, tweeters, woofers. What do they all mean? Can you suggest a good guide? What specs should I look for? How much should the amp specs and speaker specs match up?

Perhaps more importantly - what about the source of the audio? My original idea was to upgrade my sound card (I'm currently using the integrated motherboard sound chip and RCA-out) and just do RCA out to the receiver. But a few folks have suggested that using a USB DAC is the way to go. I'm not familiar with such equipment - I've read some people use an external sound card with SPDIF out and send that through the USB DAC and finally to the amp/receiver. I've also read that one would simply plug the USB DAC in and send the output to the receiver from there.

Has anyone used a USB DAC with linux [specifically, fedora] before? How well do they get along? What sort of prices are we talking about for a USB DAC? Will I really notice a difference considering my budget?

Many thanks,

meb.

Recommendations for a linux PC-based sound system - on a budget for a

Reply #1 – 2011-12-19 23:19:24

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Has anyone used a USB DAC with linux [specifically, fedora] before? How well do they get along? What sort of prices are we talking about for a USB DAC? Will I really notice a difference considering my budget?

Hello, I can't tell you "what" exactly is going to work as everyone opinions are different. Here is the setup I am using that works with Fedora 15 (Lovelock) though if you are interested. I have an older high-end external sound card the M-Audio Revolution 5.1 card that works and plays very nicely with ALSA due to the fact that the chipset is ICE1724. I highly recommend whatever card you get you make sure it's an external sound-card (especially with Linux). I am not a hardware guy, but SPDIF is probably the best way to go to answer your question as the Revo has support for it. I think that about sums it up. In terms of guide somebody else who has more "hardware knowledge" can probably answer that for you. Take care.

Recommendations for a linux PC-based sound system - on a budget for a

Reply #2 – 2012-01-10 23:05:51

Isn't it pointless to pay for a soundcard if you're gonna use SPDIF? Just use the on-board sound chip for that.

Recommendations for a linux PC-based sound system - on a budget for a

Reply #3 – 2012-01-11 21:18:21

I suggest you go to a stereo shop and listen to some speakers (and maybe amps & receivers).

Most specs aren't that useful... But, it is good to understand the terminology. On the electronics side, most modern equipment is better than the human ear and you generally won't hear any difference anyway (except for amplifier power).

With speakers it's a different story... All speakers sound different, but different manufacturers use different measurement standards and they often "fudge" the results. You can probably get a better idea of how the speaker sounds by looking at the size & overall design of the speaker than by reading the specs... But, there's no substitute for LISTENING!

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Perhaps more importantly - what about the source of the audio? My original idea was to upgrade my sound card (I'm currently using the integrated motherboard sound chip and RCA-out)

If you have a single RCA connector, that's digital (S/PDIF). A "better" soundcard won't give you "better" digital data. If you have a pair of RCA connections (left & right), that's analog. If you don't hear noise, a better soundcard is unlikely to improve the sound. If you are getting noise from your soundcard's analog outputs, a better soundcard should help to reduce/eliminate the noise.

External DACs can be expensive with little or no sound-quality advantage. If you have a digital connection to your reciever, you are already using the DAC built-into your receiver.

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There's all sorts of specs I don't understand - amplifier power output...

This is a tough one. Under normal listening in an average living room 10 or 20 Watts is usually plenty. For loud parties, you might need 100-200 Watts, or more. Bass requires more power than mid & high frequencies, and it probably takes at least 100W (and big speakers) to "shake the walls". Perceived loudness depends the average power level, but you need "headroom" for the peaks.

Since our hearing is logarithmic, a doubling of power (which is a 3dB increase) doesn't sound much louder and it takes 10 times the power (a 10dB increase) to be perceived "twice as loud". Very loud music requires LOTS of power and big speakers.

A speaker's power rating is the maximum power you can pump into t (without burning it out). But, because of the relationship of peak and average power, JBL says you can safely use an amplifier with twice the power rating of the speaker, assuming you are not driving the amp into distortion. (i.e. You can use a 200W amp with a 100W speaker). That also assumes that you can trust the manufacturer's specs...

The power consumption of an amplifier is the amount of power it takes out of "the wall". Most solid state amps don't require much power when idle, or when running at low volume. Usually this is not a big concern. Tube amps are inefficient... They consume more energy and heat-up even when idle.

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speaker sensitivity...

This is the loudness of the speaker, usually measured at 1 meter with 1 Watt of white noise. A speaker with higher sensitivity will play louder (with the same power from the amp). In theory, you could calculate how much amplifier power you need... In reality, you usually don't know exactly how loud (dBSPL) you will be listening or how your room acoustics will affect the loudness...

Some speaker manufacturers will give a minimum recommended power spec. The sensitivity rating is probably a better spec to use if you are comparing two different speakers.

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fequency response...

Frequency is related to pitch. Bass is low frequency, treble is high-frequency. The normal human hearing range is considered to be 20 - 20,000Hz.* If the equipment has a frequency response that is "flat" from 20-20kHz (or a wider), this is ideal. If you had a piece of equipment with frequency response is 150 - 5kHz, the high and low frequencies would be missing (similar to a telephone).

There should be a decibel range given too. i.e. 20-20kHz +/- 1dB. Decibels are related to loudness and one dB is considered about the minimum difference (in loudness) that you can hear.* So, if you listen to two tones (of the same frequency), and one tone is 1/2dB louder than the other, they will sound equally loud. If you have a spec that says 20-20kHz +/-10dB (or with no dB tolerance given) the spec is useless and the highest & lowest frequencies may be very weak.

20-20kHz +/- 3dB would be excellent for a speaker (very-few very-expensive speakers can achieve this). The same spec for an amplifier is lousy... It's easy to make an amp that's flat 0-100kHz +/- 1dB (far beyond the range of human hearing).

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speaker nominal impedance...

Usually not important, since most home speakers are 8 ohms, and most receivers & amps work with 8-ohm speakers. Impedance & resistance (ohms) are related to current & power. With lower impedance, you generally get more power out of the amp (assuming the amp is capapible).

If you wire two speakers in parallel, the total impedance is cut in half. If you are running a speaker at 10 Watts, and you connect a 2nd speaker (with the same impedance) in parallel, the 2nd speaker gets 10 Watts too, for a total of 20 Watts. Most amplifiers are rated at higher-power (sometimes twice the power) at 4 ohms. If the speaker impedance is too low, you can burn-out the amp. If the speaker's impedance is higher than the amp's rating, you'll get less power but there's no danger of anything bad happening.

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...tweeters, woofers.

A cheap speaker might have a single full-range speaker. But, it's hard for small speakers to put-out bass, and it's hard for big speakers to put-out high-frequencies. A 3-way hi-fi speaker has a woofer for the mass, a midrange for the middle, and a tweeter for the high frequencies. A sub-woofer is for very-deep bass, but in cheap computer speakers the small "subwoofer" is more like a mid-woofer. For "loud party music", I'd say you need 12-inch woofers (or subwoofers) as a minimum.

* These are approximations & generalizations... Some people have better hearing than others...

Recommendations for a linux PC-based sound system - on a budget for a

Reply #4 – 2012-01-12 02:17:34

Quote from: DVDdoug on 2012-01-11 21:18:21

I suggest you go to a stereo shop and listen to some speakers

That is probably the best piece of advice offered. There is one other area that deserves particular attention, and that is resampling. You mention your budget and this pretty much defines that you will be using a soundcard that doesn't support hardware mixing, so your OS will be responsible for resampling the audio. Most very cheap or integrated soundcards can output 44100 and 48000 KHz, and some will also output 88200, 96000, 192000. Vendors, manufacturers and retailers can be remarkably reticent about describing the actual capabilities of their products, regardless of whether those capabilities exceed the marketing claims or not. I found alsacap useful in quickly identifying the actual capabilities of my hardware http://www.volkerschatz.com/noise/alsa.html. Resampling audio with a low quality resampler will often result in audible artefacts. Most cheap/integrated PC soundcards will, by default, resample eveything to 48000 KHz and use a very low quality resampler to do so (because an undemanding but low quality resampler will work on any hardware). This is fine for AC-3/DTS playback which is typically at 48000 so isn't resampled, but less than ideal for other audio such as CD at 44100.

Linux's ALSA, like other OS's audio systems, uses a very crappy but undemanding resampler by default. I'm assuming that as you're posting on HA that your main priority is CD audio, or audio derived from CD i.e. 44100 KHz. If this is the case then you should make sure you have installed libasound2-plugins (Debian and derivatives) or libasound2 (I think this is the equivalent in Red Hat/Fedora....you should check for yourself) and then edit either /etc/asound.conf or ~/.asoundrc to read

Code: [Select]

defaults.pcm.rate_converter "samplerate_best"
defaults.pcm.dmix.rate 44100

This ensures that your CD derived audio is not resampled, and that any audio that is not 44100 gets the best quality resample (resample is very CPU intensive). edit: that was assuming your soundcard is not incapable of 44100 output; I recall that there were some cards such as original Creative Audigy that could only output 48000. end of edit. Of course if your main priority is audio at another sample rate then you should change that figure of 44100 as appropriate.

The ideal situation would be to have a really nice soundcard that handles resampling and mixing multiple sources itself so well that you never need to consult the ALSA docs or care....meanwhile, back in the real world of budget audio...

Someone mentioned external vs. integrated audio. If your integrated audio doesn't make any nasty noises and isn't obviously deficient then you might as well use it. You'd have to have something very old and very cheap to find yourself with a really bad sound card, though it isn't impossible. USB connected cards will have the benefit of not generating noise from memory access or CPU loading, but a cheap USB card can be as crappy as the worst integrated. If your integrated Intel HDA chip (or similar) doesn't do anything nasty then use that.

Recommendations for a linux PC-based sound system - on a budget for a

Reply #5 – 2012-01-12 05:41:13

IMHO you should:

Choose a soundcard well supported by ALSA (please refer to the ALSA Soundcard Matrix). Personally, I would choose an M-Audio card in term of of cost vs quality.
Output to hardware directly by not using Pulseaudio and Dmix or use Jackd to ensure bit perfect output (no resampling). If the soundcard have a hardware mixer, make sure the rate is locked. However, if the card have a high quality resampler, it might not matter to you. Personally I am satisfy with my Revolution 7.1, so I don't bother to lock the rate.
Use a good pair of studio monitors.

Recommendations for a linux PC-based sound system - on a budget for a

Reply #6 – 2012-01-12 07:33:12

Quote from: mebassett on 2011-12-13 18:17:44

Has anyone used a USB DAC with linux [specifically, fedora] before? How well do they get along? What sort of prices are we talking about for a USB DAC? Will I really notice a difference considering my budget?

Hello, I started a topic a few months ago because I wanted to find a good USB DAC for music listening and occasional recording for both linux and windows. I ended up buying a Native Instruments Komplete Audio 6 for 200 EUR on ebay which works great under my Ubuntu Studio 11.10, however it needs linux kernel 3 to work and it is not officially supported. I just needed to add a PulseAudio profile set to map the channels properly (it had an odd mapping of 6 output channels).

However, this card might be an overkill if you just want stereo sound playback.

Recommendations for a linux PC-based sound system - on a budget for a

Reply #7 – 2012-01-12 17:17:56

I'm using M-Audio Mobile Pre Mk II in Ubuntu 8.04 (a vintage distro and it works out of the box. I need to have it connected to the PC prior to booting (otherwise ALSA does not register it, prolly some bug which may fixed in recent distros) and the SW volume control does not work (only the HW knob on the device), however.

It's not an audiophile card (48kHz/16 bit max., unimpressive signal-to-noise/crosstalk) so if I was making a decission like you are, I would probably pick a more serious M-Audio listed in the Alsa matrix mentioned above.

The problem with M-Audio may be that you're getting a lot of stuff that's only for music production (XLRs + mike preamps + phantom + mixer) which increases the price.

Recommendations for a linux PC-based sound system - on a budget for a

Reply #8 – 2012-01-13 04:04:22

Quote from: Martel on 2012-01-12 17:17:56

The problem with M-Audio may be that you're getting a lot of stuff that's only for music production (XLRs + mike preamps + phantom + mixer) which increases the price.

I recommend the M-Audio 2496, it is very reasonably priced these days and is well supported by ALSA:

https://encrypted.google.com/search?q=m-aud...085&bih=485

Recommendations for a linux PC-based sound system - on a budget for a

Reply #9 – 2012-01-14 00:32:54

I'm using an M-Audio Audiophile USB off ebay for 40 pounds. They are old boxes now but still sound excellent, you can probably pick one up on ebay. ALSA requires that anything sent to is it in 48khz but Deadbeef's resampler will do that for you just fine.

I've also used it for movies and gaming on Linux and it works just fine.

As for your budget setup: I bought a pair of Mordaunt Short 902is and a NAD C320BEE off ebay for around 300 GBP. They pair with the Audiophile great and will fill a decent sized living room.

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