How safe is tuning with a carpc?

Excellrec · 07-08-2008, 01:40 AM

On my next install I'd like to implement a pc for all my processing functions but I have some concerns. I come from a pro-audio background and am very familiar with all the plug-ins, programs and etc. I also know from this background that you can have failures or crashes that if implemented the way I'm thinking could be catastrophic to a system.

For instance, in some situations I've seen/had blue screens come up on windows machines and induce audio errors such as... full blast square wave as the system froze midway through audio output and sort.. skips there. Now if I were running software based crossovers and they failed while this happened, that would mean that full level square wave at 400hz might get sent to my $300 set of tweeters and destroy them pretty much instantly. Now it's a rare occurence but if it happens just once it's gonna be costly.

So I'm wondering if people have considered solutions, dealt with such failures or anything in a carpc with such a setup. I can't imagine a carpc could be any more stable and probably a lot less stable than a home pc with regulated ac input. Say.. if the battery dies abruptly or falls below working voltage for the pc, now that usually causes an abrupt pop from the sound card and there again.. will destroy tweeters and other speakers instantly. So do people just pray for it not to happen? How is this addressed?

colin · 07-08-2008, 02:33 AM

The pops are all controlled by shutdown controllers now. If your battery drops too low, the controller will kill the remote line for your amp, then softly shut down your computer.
As far as the square wave... highly suggest hardware crossovers. Even cheap crappy ones are better than risking your speakers! It's not like you lose sound quality with crappy crossovers from what I've seen...

RamonM · 07-08-2008, 09:54 AM

Let me know how this goes cause a buddy of mine has the same problem

durwood · 07-08-2008, 12:05 PM

I've not had any issues over the last year and a half running the VST/ASIO method other than turn off pop. I fixed that with a PAC TR-7. Now this is not to say something else might not go horribly wrong. If I shutdown Console, then there is no software route for the sound to get to the hardware. This might purely depend on hardware and how stable the soundcard drivers or 3rd party audio stream routing is done.

Ways to protect your speakers (and maybe your hearing):

1) Kill switch on amp remote turn on wires for instant off in case of "problems"
2) Analog volume control inserted between computer and amp(s)
3) Capacitors inline on tweeters to protect them (6dB high pass filter). Pick a high frequency below your filter frequency as to not affect it but still offer protection from frequencies that could damage tweeters from overexcursion.

As for square waves: this can affect any speakers. The only way to possibly protect against that is probably a properly sized light bulb that acts as a protection fuse. I have never seen a computer output square waves if they freeze-stutter yes (but that is not a square wave), does this mean it can't happen? I don't have an answer for that, but I would sure hope GOOD soundcard manufactureres worry about such problems for you.

There is a huge long thread over on DIYA on using the PC as a home based XO. I'm quite sure this topic had to have been brought up considering some of those guys could be running speakers costing well into the thousands upon thousands of dollars.

Excellrec · 07-08-2008, 03:57 PM

Thank you for your thoughts Durwood.

I had considered the passive crossover failsafe on the tweets but with it in mind to keep things as simple as possible I was trying not to put any more components in the path than necessary. Though I think I might just bite the bullet on that one.

It has proven true in my experience that a good soundcard will not produce errors near ever. Though it has also proven true in my experience that a lot of the relatively cheaper soundcards such as the soundblasters and etc will cause a ton of problems particularly if you're trying to process audio in real-time. So I figured somebody around here has run into problems with those. I might just have to drop about $500 on a soundcard just to get the piece of mind. But even with that said most of the problems I have seen come from the os having problems with driver problems, hdd failures and computer power supply failures. I've had $150 dollar antec power supply's go out on me on my home system and cause the freezing and audio stuttering I reffered to, so in other words.. it's hard to be 100% sure something won't fail because even robust components do and have failed on me.

I do like the idea of a kill switch on the amp remotes. I plan to control all the turn ons and temps as well with a plc so I might just rig that to auto cut all the amps if the system drops to a certain voltage above the computer cutoff voltage and hopefully that will be reliable. I will probably also install a hardware switch for the remotes just to be extra sure I can turn those things off in an emergency. I also plan to set the plc to delay amp turn-ons and turn-offs to after and before computer boot and shutdown so that should solve any turn on pops.

If there are any other precautions I can take please let me know. I plan on running about $2000 worth in just raw drivers alone so a catastrophic failure is out of the question for me.