Using a HTPC as a crossover/EQ?

Discussion in 'Archived Threads 2001-2004' started by James Mudler, Feb 6, 2002.

  1. James Mudler

    James Mudler Stunt Coordinator

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    Does anyone know of any hardware or software that I can use as a crossover and/or eq in conjuction with a PC?

    I am interested in features like the new QSC DSP 30 or Cinema line? I am currently bi/triamping my LCR's and would like higher quaility crossovers (currently using some crate xo's).TIA
     
  2. Ken Woodrow

    Ken Woodrow Stunt Coordinator

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    There have been a few threads in AVS Forum about the related topic of using a HTPC as a preamp, with bass management, room correction, and software surround decoding, but the general consensus is that the software is not there yet. For reference, check out this advanced thread.
    Your best bet might be to go to a high-quality analog solution, like the Marchand line of active crossovers.
    The concept of using a programmable PC to experiment with different crossovers and filters, and then to see the results using RTA software, is certainly sound. AFAIK, however, the software to do the former is just not available yet, certainly not for the HT market. It could be that some of the recording software suites designed for MIDI and home recording could do it, but I don't know much about that world.
    Anything your research turns up, however, please share with us.
    - Ken
     
  3. James Mudler

    James Mudler Stunt Coordinator

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    Thanks Ken,
    I have that thread bookmarked and been keeping a eye on it. To be honest, it is kinda over my head [​IMG] Seems they are looking for a digital solution where analog, for now, would be fine. Thanks again.
     
  4. ThomasW

    ThomasW Cinematographer

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    James

    John Gorden of QSC says the DSP-30 and soon to be released DSP-40 have good sound quality. I am leary of low buck digital devices. But am going to get a DSP-40 for audition when they become available.
     
  5. John A. Gordon

    John A. Gordon Stunt Coordinator

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    Yes, the DSP-30, and the DSP-4 (not 40), have good sound quality. As for the "low buck" concern, not an issue. When you do enough volume, costs are lower, which means we can translate lower costs to the end users.

    James, what specifics are you looking for? Types of crossovers? Filters, etc?
     
  6. Brian Bunge

    Brian Bunge Producer

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    John,

    Any chance the DSP-30/DSP-4 can act as a stereo 3-way, 4th order crossover as well as a parametric EQ? If so I'd get rid of my Behringer unit and go with an all in one solution. How many bands of EQ can it do? I eagerly await Thomas' audition!

    Brian
     
  7. James Mudler

    James Mudler Stunt Coordinator

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    Thanks guys.

    Brian pretty much hit it on the head. I currently have Biamped my front L&R and Triamped the Center. My speakers are the Audax HT design. My processor is a Lexicon DC-1 and I currently have 2 Crate X-O's (2 way stero 3 way mono). Ampilifers are two Kenwood KM-Z1's (130 x6ea). 24bd slopes Linkwitz-Riley X-O and 2-3 eq bands would be all I need. I have Purbits /Sample Champion software and have a few trouble spots 3-4 db cuts would take care of it. I can't remember off hand at what freq.

    My knowledge is under par here, but the unbalanced to balanced conversion concerns me. I have a hard time reaching reference levels at the moment. I also have a low hiss in my front stage (it drives me up a wall. I am thinking the 4 v to 10v "thing" may be the cause.

    The Dsp-3 or 30 looks like a perfect solution. Crossovers, eq, and signal voltage adjustments all in one. From reading the manual, I think I would need 4 of them. I also noticed street price of $360 for the Dsp 30 or the dsp 3. Is that right? I would think the rack mount would be higher. Is a 3 or 4 channel version comming? Thanks for the help.
     
  8. John A. Gordon

    John A. Gordon Stunt Coordinator

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    The DSP-3 and DSP-30 (as well as the upcoming DSP-4) are 2-in, 2-out. To do tri-amp, you would need two units.
    As for crossovers, its your choice:
    - Butterworth 6, 12, 18, or 24dB per octave slopes
    - Bessel 6, 12, 18, or 24dB per octave slopes
    - Linkwitz-Riley 6, 12, 18, or 24dB per octave slopes
    The total number of parametric bands you can add is not a specific quantity. Total number of EQs (filters, delays, etc.) is dependent on memory. But it is safe to say that if all your are doing is EQ, you can easily drop in 10 parametrics per channel--not that you would want that many--and still have some memory left over.
    The DSP-3 and DSP-30 starts with a blank screen. You configure to your needs or desires. If you want to play with the software, you can download it from our website. QSC Audio
     
  9. James Mudler

    James Mudler Stunt Coordinator

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    John,
    Looks like you have a real cool product on your hands. I guess I could use the extra memory as subsonic filters, etc. What is the difference between the 30 and 40? Is the lower freq adjustments the only difference? As for the extra channel (2 units) for a triamp application, I'll just use the extra channel for LFE. I just can't let a channel go unused [​IMG].
     
  10. Brian Bunge

    Brian Bunge Producer

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    James and John,

    Well hell! It looks like I'd need two units! What I want to do is place a L/R 4th order crossover around 200Hz between my bookshelf speakers and my dual 12" subs that will be working in stereo. Then I wanted a crossover point around 60Hz between the dual 12's and my Blueprint 1803. At the same time I wanted to be able to use the parametric EQ up to around 100Hz.

    Looks like I'll just need an outboard crossover and then keep my BFD for EQ duty!

    Brian
     
  11. Jack Gilvey

    Jack Gilvey Producer

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    I'm looking into modding my Dreamcast to perform all of these functions plus decode SACD, I'll let you know how it goes.
     
  12. ThomasW

    ThomasW Cinematographer

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  13. Ken Woodrow

    Ken Woodrow Stunt Coordinator

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    I checked out the PC software control for the QSC DSP-30 -- very impressive. It essentially lets you build a signal chain and modify it to your heart's content -- different types of crossovers, plus EQ, plus delay, plus variable gain -- kind of like playing with blocks. I did not know that it was possible for the software to have such control over the DSP chip. I frankly don't see why it would not be possible to put several DSP chips on a PCI card and implement the same type of control in a PC.

    The biggest limitation of an all QSC system, IMO, is that each DSP-30 is capable of outputting only two channels, so you would need to daisy chain several to crossover and EQ an entire 5.1 system. Even at the relatively bargain price of the QSC gear, buying several could put you into TACT and AudioControl DiVa territory.

    But the QSC is a great alternative to a Behringer Feedback Destroyer, particularly given the quality of the software control.

    The QSC also would be great for speaker builders, in that you could experiment with different types of crossovers until you found one that worked with your drivers and cabinets. Then you could wire a passive crossover to match or use an active one like those from Marchand.

    - Ken
     
  14. James Mudler

    James Mudler Stunt Coordinator

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    Agree Ken, 4 units at $360 = $1440. There are some options at that price point. But still a value at the single unit price. I which they would make a 4 input/output unit with assignable inputs. Meaning you can use 1,2,3 or all 4 inputs and assign the inputs to various 1-4 outputs. Doesn't seem that difficult, it would eat memory, change the software. I think it would be a neat unit. You can do a wild 2way with filters from hell, or a basic 4way - the choice is yours...and all with 1 one or several inputs.
     

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