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 Post subject: PC selection
PostPosted: Thu Aug 15, 2013 2:05 pm 
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I had several discussions yesterday with people who want to buy a few dozen PC's to run Stereo Tool. The information that I gave them is probably interesting for others as well, and beside that, other users may have more tips. So I decided to create a new forum section and post the info here.

Note: The text below is aimed at FM stations, that use all the settings in Stereo Tool (including declipper, natural dynamics and FM composite clipping).


Sound card
If possible, go for the Marian Trace Alpha. (Marian Trace Pro if you need AES/EBU digital input). Both are PCI-based, if you want a PCIe-version, you'll need the more expensive Zeraph AD2.
They may be hard to obtain though - don't wait too long with ordering. Alternatively you could go for the ESI Juli@, which is slightly less 'tight' (you'll probably loose a few % in loudness, 0.5 dB or so).

CPU speed
This is the single most important thing to run Stereo Tool.

I haven't checked prices recently, but I would go for an i5 or i7 (from the viewpoint of Stereo Tool there's no real difference between the two, i7 has Hyperthreading but Stereo Tool does not benefit from that).

For a CPU benchmark see: http://www.cpubenchmark.net/cpu_list.php
Click on a CPU, and in the details page you'll find the single thread rating.

Example: My now 4.5 year old development laptop:
Intel Core i7-2630QM@2.00GHz 5564
On the details page http://cpubenchmark.net/cpu.php?cpu=Int ... GHz&id=873 you can find that the single thread rating is 1313.

I can run a complete preset, including Declipper, Natural Dynamics and FM composite clipping on this system with a bit of headroom. If I enable the Stokkemask (ITU-R.1268) mode of the composite clipper, I need to lower the Quality slider to 85% to be able to run it - with very little headroom.
Edit: This was the case with version 7.30. With 7.40, I can easily run the whole preset including Stokkemask with sufficient headroom.
Edit 2: With version 7.71 the CPU load on the highest used core for a complete preset including Stokkemask is about 45%.

Quality slider effect on the CPU load: At Quality 0% the CPU load would be exactly 50% of that at Quality 100%. So with the Quality slider set at 85%, I need (50 + 50 * 85%) 92.5% of the CPU load when running at 100%, which means that to run at 100% I would have needed 1081 / .925 = 1168. So for version 7.30 of Stereo Tool with all these options enabled, the result of the above calculation for a CPU should be at least 1200.
Due to the update above, a value somewhere between 900 and 1100 should be sufficient. Note however that future changes might increase this value again.
In version 7.70, the used CPU load is 45%, with single thread rating 1313 (however, I ran the Passmark software on it, and found 1441, so I should use that value instead). This means that the amount of CPU used is 1441 * .45 = 648. So, you would need at least 700.

Take one of the new Haswells you get:
Intel Core i7-4790K @ 4.00GHz - Single thread rating is 2532. So the expected CPU load on the highest used core is about 700/2532 = 28%.

Single thread ratings are usually roughly the same for the same models of i3, i5 and i7, so unless you're planning to run a large number of Stereo Tool's on a single pc, you can often buy a much cheaper CPU. Stereo Tool currently (!) uses 2 cores, so there's little benefit in having more than 2 cores. Except for one thing: If you want to achieve low latency, you need to have 2 cores that are dedicated to running Stereo Tool, and core 0 is usually used for drivers. So, you want to avoid using core 0 for processing, which means that having 2 cores isn't sufficient. If the cores are fast enough you can run Stereo Tool on a single core, but then the latency will also be slightly higher.

Note: These values are estimates, system speed is also determined by other things such as the motherboard, memory, etc. But it gives a good indication.

Harddisk
For stability, get an SSD harddisk or a memory card. I heard from someone in the military that they use memory cards instead of SSD harddisks because - according to him - SSD harddisks tend to fail more often than those (simpler) memory cards. You need a cardreader, and I don't know how reliable Windows is with this.

Size isn't important, as long as you can store the OS and Stereo Tool (approx. 1 MB) on it. You can get a 60 GB SSD harddisk for about 45 euro / $60.

Memory
There are multiple sizes of memory chips; the bigger ones get less hot so get those. There's no difference in speed or price.

In most motherboards, if you place memory in multiple banks, the CPU can access them in parallel, effectively doubling memory speed. So, it's better to get 2 1 GB cards than 1 2 GB card. See your motherboard manual.

The amount of memory is not really relevant, it needs to be enough to run the OS, and have a few hundred MB left to run Stereo Tool. Depending on the OS, even 1 GB suffices in most cases.

CPU temperature
Try to get a CPU that doesn't get insanely hot. What I heard (but I have to look into it, I basically only read a post from someone on my forums), is that the new Haswell chips use less power and hence get less hot. They are also insanely fast. Haswell chips are the i5/i7 4xxx numbers.

Power supply
You might want to go for a redundant power supply. I have never experienced a failing power supply, but I know that many hardware processor boxes have redundency.

Fans
Make sure that you use good quality fans. If anything breaks in a pc, in my experience, it's usually the fans. The fans are the only moving parts in the pc.

Operating system
Stereo Tool runs on:
- Windows 95/98 (no 192 kHz FM output)
- Windows XP (SP2 needed for 192 kHz FM output)
- Windows Vista
- Windows 7
- Windows 8
- Linux (tested several flavors)
- Mac OS X

Turn off everything you don't need (especially automatic software updates that cause reboots).

If you're going for Windows, audio is easiest to setup under XP and the performance with the GUI open appears to be slightly better. But it's not officially supported anymore.

Many people have already reported running Stereo Tool on Windows without a single glitch in multiple years. The Linux and Mac versions are new and have not yet been tested this thoroughly, although I don't expect any issues. Once Stereo Tool runs, when you don't touch it it only repeats the exact same action over and over again; it doesn't allocate or release memory, it doesn't use the harddisk, so there isn't much that can go wrong - this is very different from how most software works.

Other notes
Don't put in things that you don't need that will increase the temperature. Especially avoid video cards etc, they tend to get hot and there's no need at all to put one in - since nearly all motherboards have a built-in video output.

Budget
These pc's aren't exactly the cheapest, and many stations run with much cheaper E8xxx and E9xxx series without any issues. Lowering the Composite clipping strictness a few steps won't really cause any issues, and if you're running at latency 4096 you can also reduce the Quality slider a bit. But if you want to use everything and have headroom for potential future enhancements then I would go for something faster.


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 Post subject: Re: PC selection
PostPosted: Thu Aug 15, 2013 9:39 pm 

Joined: Mon Feb 04, 2013 11:25 pm
Posts: 143
Good post.As far as media I would prefer the SSD over a memory card.Not sure what the military uses them for, but i wouldn't trust a medium who concept was for storing pictures , I might consider it as a secondary drive but definitely not for primary. imho


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 Post subject: Re: PC selection
PostPosted: Thu Aug 22, 2013 4:32 pm 

Joined: Mon Feb 04, 2013 11:49 pm
Posts: 182
Excellent post Hans--thank you!


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 Post subject: Re: PC selection
PostPosted: Tue Sep 24, 2013 2:20 pm 

Joined: Sat Oct 10, 2009 11:00 am
Posts: 106
Quote:
CPU temperature
Try to get a CPU that doesn't get insanely hot. What I heard (but I have to look into it, I basically only read a post from someone on my forums), is that the new Haswell chips use less power and hence get less hot. They are also insanely fast. Haswell chips are the i5/i7 4xxx numbers.
Indeed, Haswell chips are cold - go for i5-4440 (I currently use that in production) - at ambient air temp of 25 Degrees Celsius the CPU is at ~30-32. This is with the stock (box) cooler.

On the other hand, the i7-4770 @ 3.9 GHz can run almost twice more instances of Stereo Tool, compared to the k5-4440 @ 3.1 Ghz but it gets quite hot - ~50 Degrees at the same conditions.


And ... you must avoid AMD processors - they do not work that well with Stereo tool.
Quote:
Power supply
You might want to go for a redundant power supply. I have never experienced a failing power supply, but I know that many hardware processor boxes have redundency.
Around here in my area cheap (weighting approx 300 grams) PSU''s are very common (they are put in almost all sold configurations by default), and believe me, they fail a lot!
That's why go for GOOD PSU (Enermax, Corsair,... etc.) Also it's not a bad idea to consider an UPS. Here good quality UPS costs as much as good PSU.
This is *very* important, because this way you can ensure hardware stability and safe 24/7 operation.
Quote:
Fans
Make sure that you use good quality fans. If anything breaks in a pc, in my experience, it's usually the fans. The fans are the only moving parts in the pc.
Go for high-quality ball bearing FAN's - for me Zalman are very quiet and reliable for years to come and are quite cheap, around 5-10 euro.
Quote:
Budget
These pc's aren't exactly the cheapest, and many stations run with much cheaper E8xxx and E9xxx series without any issues. Lowering the Composite clipping strictness a few steps won't really cause any issues, and if you're running at latency 4096 you can also reduce the Quality slider a bit. But if you want to use everything and have headroom for potential future enhancements then I would go for something faster.
In time of writing this - you can get a perfectly fine parts for around 250 euro generally (almost) everywhere in Europe. Or get an used PC for 100 euro or less that will do just fine in most cases.


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 Post subject: Re: PC selection
PostPosted: Fri Nov 15, 2013 3:49 am 
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Joined: Mon Mar 17, 2008 1:40 am
Posts: 9471
Some interesting things about capacitor quality on motherboards are being posted here:
http://radiodiscussions.com/showthread. ... oder/page4


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 Post subject: Re: PC selection
PostPosted: Thu Dec 19, 2013 4:50 pm 

Joined: Thu Dec 19, 2013 4:44 pm
Posts: 6
hello all,

all above posts are really interesting, stereo tool also, but i have a question...
whats the delay added with stereo tool ?
in a fm radio station using orban as a compressor/limiter/xxx/xxx only musicians can listen to a small delay, between the actual sound and the sound which is coming from the air.
in most cases, radio producers cannot find a delay, while speaking..

so, using a "heavy" pc with stereo tool, could we replace an orban or an omnia processor ?


regards,

George


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 Post subject: Re: PC selection
PostPosted: Thu Dec 19, 2013 5:15 pm 
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Joined: Mon Mar 17, 2008 1:40 am
Posts: 9471
Hello George,

This is more something for a different forum section, but I'll give you a brief answer.

Latency is related to quality. As in: Less latency also means less quality. Because of that, with Stereo Tool you can also send audio to a monitor output with low latency (typically about 11 ms) - for this to work you need to have a sound card with multiple outputs (if you use multiple sound cards, there will be timing issues between them, and fixing those requires adding extra latency).

For FM, the lowest latency that gives a 'reasonable' quality is about 28 ms (the speed of the pc has a small impact on this number, but we also need to have some audio available to 'work with' and that's about 23 ms, so only 5 ms is caused by the pc). 28 ms is acceptable for some people but not for others. At the best quality setting, the latency is over 100 ms, which is really too much for monitoring. So if you want to have the best possible quality, use that setting and the monitoring output. Some stations also use a different compressor (an old Optimod for example) for studio monitoring while creating the actual FM signal with Stereo Tool.

By the way, most of the newer hardware processors also have a bigger latency - upto over 1 second!


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 Post subject: Re: PC selection
PostPosted: Sat Dec 21, 2013 6:08 pm 

Joined: Mon Feb 04, 2013 11:49 pm
Posts: 182
Is there any benefit to Pro vs Home versions of an OS? And is Windows 7 as reliable as XP for ST use? I read a post something like "it's Windows 7, what did you expect?" when someone was having a problem.


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 Post subject: Re: PC selection
PostPosted: Sat Dec 21, 2013 8:32 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 3312
Ofcourse XP 32bit pro for dedicated FM PC. Period.
Never tried, but "home" should also do the job.


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 Post subject: Re: PC selection
PostPosted: Sat Dec 21, 2013 9:43 pm 

Joined: Mon Feb 04, 2013 11:25 pm
Posts: 143
Ditto!!! If you have to use 7 just use 32 bit.


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