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Multi-Way Conventional loudspeakers with crossovers

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Old 16th July 2006, 10:44 AM   #491
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In general even a "decent" soundcard is more than good enough not to be the weakest link in the chain. Don't go mad at this stage worrying about the "quality" of the soundcard - this is NOT the hardest part of the project...


"Noise" from the PC normally means that loud annoying whirs from the damn thing which are hard to remove without subsequently cooking the darn thing
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Old 16th July 2006, 10:52 AM   #492
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Actually, I am looking at this for a car installation, so reducing inducted noise throughout the entire chain is my main goal, as well as providing 16 channels with as little components required on the PC as possible, so if I can remove the soundcard entirely, and reduce noise in the process, it will suit the requirements I need perfectly. I thought it might be beneficial in this instance beacuse it provides 16 channels in a fairly simple form, for a comparable cost to a good soundcard.
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Old 16th July 2006, 04:19 PM   #493
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Stop using the word noise because you are being ambiguous. I honestly doubt that if both devices are powered from the same "noisy" powersource that it makes "much difference" if you use an internal card powered by the PC PSU, or an external DAC powered by it's own PSU. Do you see the logic?

For sure a high end external powersupply is likely to beat a PC powersupply, but measurements of decent soundcards suggest that they already add decent decoupling and hence are "fairly" well immune to external inducted noise.

Do ensure that you get a PSU designed for wide ranging DC inputs - my limited testing so far suggests that a simple 12V input computer PSU is NOT designed for vehicle input and instead it needs a regulated 12V supply. It will work, but it's not too resiliant and doesn't regulate the computer internals very well

Most high end soundcards have SNR around the >105/110 level. This is up there with a decent hifi CD player. So induced "noise" is certainly NOT your main worry.

(After all lets assume 40dB ambient noise levels, this would mean that you would have the audio at 150dB before the induced noise was even at ambient levels... You would be deaf inside a few minutes at those levels so I don't think induced noise is really an issue?)
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Old 16th July 2006, 05:09 PM   #494
Thunau is offline Thunau  United States
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There are a few manufacturers that make external firewire sound cards. I have a Presonus Firebox, which is a 6 input/8 output (that includes stereo digital in and out) interface, but they make other, bigger configurations as well.
There are the RME (expensive), Mark of the Unicorn, M-audio, Focusrite, Echo offerings you might want to look at. They all are made for the recording market, but work just fine for PC crossover duties.

As a bynote, just because a sound card is external doesn't mean that it is immune to electrical noise from the computer. After all there is a wire connection between the motherboard and the interface. A bad design will let the power supply noise into the converters. I had a USB sound card that was really noisy that way. It would not only have a constant hiss/buzz at -75dB to -80dB, but it would also have short spikes in audio.

A nice and quiet solution for me was the RME Hammerfall card connected with an optical cable to an Alesis AI-3 interface.
No electrical connection between the computer and audio interface- just a piece of fiberoptic cable. That interface sits idle with a -96dB noise floor and sounds like a nice CD player.
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Old 16th July 2006, 05:56 PM   #495
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Aetherion,

For car use, I wouldnt be too concerned about the sound card. And I would think the compactness of all the equipment would be good in the small confines of a car.

I'd rule out USB soundcards because I dont think you can synch enough channels of USB to be worthwhile for crossover use.

I havent had good luck with my MAudio Firewire Solo card. It definitely introduces audible glitches of it's own. About once a minute while listening to music there will be a slight dropout of sound.

SPDIF toslink out of the sound card to multiple battery powered DAC's might work. I'd like to find a good 4 toslink out sound card for cheap. I know RME and Lynx make some good stuff but I hate spending over $500 for a pro sound card.

Thuneau's suggestion of RME card ADAT optical out to Alesis-AI3 gets you multiple outs and decouples the PC from the sound. I have the Alesis AI-4 and use my own DAC's or Digital input receivers. I kind of wish I would have heard something positive about the AI-3 before getting a set of Benchmark Media DAC1's.

In a car setup I'd be more concerned about the PC's power supply. Some of the real low power Via PC's take 12-volt DC input and some have built in regulators for car use. But those PC's aren't powerful enough to be doing PC crossover.

Even small form factor PC's like Shuttle makes are pretty big to find a place to stick them in a car. Where would you be mounting the PC in the car? I guess I'm skeptical that you can fit a PC, extra wires, inverter, AI-3/DAC in a car.

I see the biggest value of PC digital crossover for speaker building and prototyping.

Have you considered a digital crossover from Rane, DBX, or Behringer? That sounds way easier (and cheaper to implement) and I've heard of people using a Behringer DCX2496 in the car successfully. (Although the DCX2496 is impossible to find nowadays)

I've heard that when you buy aftermarket driver upgrades for car stereo you typically get a matched passive crossover to go with it. I'd probably be more inclined to selectively upgrade the passive crossover that came with the drivers. If noise pickup is your main concern, well, those arent going to be a problem. And you dont have mounting issues of a full blown PC solution.
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Old 16th July 2006, 06:22 PM   #496
Thunau is offline Thunau  United States
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Quote:
Originally posted by Daveis

Thuneau's suggestion of RME card ADAT optical out to Alesis-AI3 gets you multiple outs and decouples the PC from the sound. I have the Alesis AI-4 and use my own DAC's or Digital input receivers. I kind of wish I would have heard something positive about the AI-3 before getting a set of Benchmark Media DAC1's.
I have no doubt that the Benchmark DAC-1 outperforms the Alesis box hands down. The one equalizing factor is that you are splitting the frequency bands between DACs and therefore eliminating some of the factors that make one DAC audibly better than other.
The AI-3 is OK as a converter. But, once you start only reproducing frequencies from let's say 3kHz up, the audible differences between it and better converters start to really blurr.
The low end on its own could conceivably be better from a high end converter due to better power supply design for example.
All in all I'm happier with the Alesis than the Firebox- purely on subjective listening impressions. Firebox seems to sound a bit harder with somewhat artificial detail.
Again, it's purely subjective, I have not measured and calibrated the levels etc.
It could be that the HF DAC in Firebox is louder than the others by half a dB and it throws off the overall sound.
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Old 17th July 2006, 08:31 AM   #497
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For a Sound Quality competition vehicle (which this will be), 'noise', be it interference, distortion, or anything else which reduces or interferes with quality is a huge issue. A lot of guys heavily modify soundcards and put better circutry on the boards to help eliminate these problems. As far as the noise floor goes, for sure, when the engine is running it helps to mask some problems, and when going down the highway this is more than doubly true, but when listening with the engine off any little bit of 'noise' that is present that shouldn't be is a problem. The current approach to this problem is to reduce the number of fans on the computer, and use larger, slower fans when they are unavoidable. DC-DC powersupplies are the most common form used in cars for the simple fact that inverters make heaps more 'noise'. The obvious drawback on using less fans is the limit that puts on processing power. From the sounds of this thread, Crossovers and other Processing done on the computer requires a much better computer than is the current 'norm' in carPC's. My thought to tackle this problem of power, allow the ability to run in digital signal as far as possible, and output 16 channels of analogue signal from a PC as cheap as possible, was the idea of running from Firewire ports on the PC to a DAC, and then to the Amplifiers. This would (I believe at least) help reduce induced interference, as long as the signal out from the Firewire ports had not already been affected by the PC itself. That is really my main worry at the moment - whether the PC will cause interference to an audio signal if it is output via Firewire. Getting back to the problem of power, Opus, a company that is highly regarded in carPC cirlces for making high quality DC-DC powersupplies, is going to be releasing a 250w powersupply in the near future. If I use 2 of them, I should have enough power capablities to run a PC powerful enough to do onboard Crossovers, EQing, Time Alignment, etc, and playback DVD video at the same time (At least that is the hope, like I said, I'm still reading the earlier posts on this thread - it's huge ). The issue of space is a large one for most car installs, however I am using a Wagon, so space, while something of an issue, is not as critical as most cars. I sincerely appreciate all your comments and suggestions, and if anyone has anything else to add I would love to hear what you think. As an aside, I have had a lot of people say I am just being stupid, or that what I am trying to do isn't possible. I realise that it isn't going to be easy, but that is part of the attraction, and like the original purpose of this thread, it is pushing the boundries of what is done with computers in regard to high end audio. That in itself makes me want to keep pursuing the project. So by all means, tell me (if you feel the need) that I am wasting my time, but please don't expect me to quit just because you do. Cheers everyone
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Old 17th July 2006, 09:06 AM   #498
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Why don't you just post your requirements instead of leaking out your needs, step by step. I personally find this approach extremely annoying

State your budget, state your goals and then people here might be able to help you achieve it

First off though be clear about what kind of noise you are talking about. Adding a fan to a PC is NOT going to affect a decent quality soundcard in terms of the audio out of the back of it. It will affect ambient "noise" though. So be clear about what kind of noise you are talking about.

External soundcards are not likely to be any more resistant to PC induced noise than inbound ones, simply because they are powered from the same powersource and have an electrical connection between them and the PC... You can't worry about chassis bourne noise and then connect your DAC and PC together using an electrical cable and say that you have isolated the chassis bourne noise!!

How many DACs do you need - this a major constraint if you need more than around 8. Give up immediately on using multiple USB/Firewire soundcards - it's very, very hard to synchronise them all. Instead stick with solutions which are designed for the pro industry and have the ability to sync each other.

Requirements on component quality goes down considerably when going active. You are putting in band limited signals into your amps and DACs and so they tend to perform better anyway.

Epia boards actually have enough horsepower for around 4x DACs + crossovers. They are usually too weak for 8x crossovers though.

You can easily get fanless Pentium-M processors which have oodles of horsepower for your needs. I don't think you need 500W of power either - consider that my AMD-64 laptop used to write this to you has a high end AMD 64 bit processor in, plus disk, 1GB ram and a flat panel screen and it's driven from a psu rated at max 120W. (it does get hot though)

Basically state your problems and I am sure that you are overspecing on the wrong items. This is such a tricky thing you are building that actually I suggest that you get it working with the cheap builtin soundcard on your computer first before you worry about the quality of the DACs - even nasty inbuilt DACs are NOT the weakest link in your chain while you get started!
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Old 17th July 2006, 09:31 AM   #499
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How many channels do you need? And how are these channels related to each other? Sometimes, it is actually better to use passive crossover (say for the super tweeters) instead of going through an active crossover.

I think you need a PCI soundcard that has the number of channels that you need. I am not sure how you get 16. Maybe you are planning on 5.1, with 3 speakers for each channels plus one subwoofer. If so, do you really need so many separate channels for rear fills?

Having said that, you can get 32 channels with these guys (as suggested by others here).

http://www.rme-audio.com/english/madi/hdspaes32.htm

http://www.rme-audio.com/english/hdsp/hdsp9632.htm

These cards will destroy anything from Alpine and Pioneer (two popular processor choices for car audio)
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Old 17th July 2006, 12:20 PM   #500
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My apologies if I am annoying anyone, I assure you it isn't intentional. If I seem lacking on knowledge in certain areas it is because I am. I have a bit of knowledge when it comes to home PC's, and bit when it comes to car stereos. This install however, will be my first attempt at a carPC, so I am still learning the ins and outs in that respect. I also know next to nothing about professional studio audio and the associated products, so if I seem ignorant about some aspects of this install it is because I am in uncharted territory for me. That said, I am very interested in all of this, and willing to learn. My requirements (and please let me know if you need more detail on any aspects - I will do my best to provide them) are as follows:
A computer to use as a source unit for audio (as higher quality audio is possible with a PC than with a car CD player), a sound processor and active crossover unit, for playing DVD movies, for use as a GPS unit, and possibly other functions I haven't thought of (expandability and system flexibility are relatively important features, but if I can get the features listed working, then honestly, I'm happy). I need a minimum of 11 channels of sound (more than that would be even better), so that I can individually control each speaker/subwoofer in the car. For this I need each channel as an Analogue RCA output, so that amplifiers with digital input aren't required (they are too rare and expensive to make a viable option). The reason I was looking at the CreamWare A16 Ultra is the fact that it only requires 2 Firewire ports and provides 16 Analogue outputs which are easily adapted to RCA, and shouldn't need a soundcard to do it. To be honest though, as long as I can get 11 or more RCA outputs from the PC, and do all the Equalizing, Time Alignment, Crossovers, and other sound processing on the PC, then thats all I want. If you need any more information from me then please ask. Thanks everyone.
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