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Thread: New CarPC - this one for tuning

  1. #11
    Variable Bitrate proph's Avatar
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    Subscribed! Nice find a bit pricey but hey... I posted info yesterday on modding the Silverstone DAC to get 3.5vRMS out of her. You can order samples of that OP AMPs (2134) or the 4 channel version (4134) from TI free of charge but wait a day until I order mine .
    Setup:
    Dynaudio 240GT
    PPI PC4100, PPI PC2350
    Zapco DSP6
    ADS DAC
    Testing new board (Albatron KI690-AM2)

    "I dont know if complaints were filed, or mistakes were made, but feelings were hurt." -Krystal Washington

  2. #12
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    sure, it's a bit pricey, but just check my signiture for my thoughts on that.

    Some people do this for fun and just tinker with it. Some people could care less about car audio, or audiophile sound in general. Everyone has something that they are really into. For some it's comeditive crosswords, for others it's crossstich, some people race cars or motorcycles, others are into gaming on a console or a PC. In every hobby out there you will find people who are very active and want to go above and beyond. Everyone has something that are really into and are willing and want to spend their money on. This is my thing.

    At this point, I want the best possible sound I can get. This is my hobby and we had a decent year, so it's not a big deal. What's pricey to some isn't even a thought to others. It's all about where you place your priorities.
    Jan Bennett
    FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

    Please post on the forums! Chances are, someone else has or will have the same questions as you!

  3. #13
    Variable Bitrate proph's Avatar
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    Shesh.. your jumpy... do your thing. I'll just observe.
    Setup:
    Dynaudio 240GT
    PPI PC4100, PPI PC2350
    Zapco DSP6
    ADS DAC
    Testing new board (Albatron KI690-AM2)

    "I dont know if complaints were filed, or mistakes were made, but feelings were hurt." -Krystal Washington

  4. #14
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    jumpy? I guess....lol

    I'm just explaining....when you tell someone what they bought is 'a bit pricey'....what do you expect?
    Jan Bennett
    FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

    Please post on the forums! Chances are, someone else has or will have the same questions as you!

  5. #15
    Maximum Bitrate TimmyM's Avatar
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    Quote Originally Posted by RedGTiVR6 View Post
    Timmy, what Dennis said is probably the case.

    I do the same thing many times just to let people know that I'm interested in what they are doing.
    Thats cool. I wasn't trying to be an *** even though it comes quite naturally to me, I see it all the time and just thought people didn't know how to subscribe without posting.

  6. #16
    MySQL Error scott_fx's Avatar
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    very cool red..i gotta say i'm a bit jealous about how tech-geeky you're getting.

    where you going to put this beast? i remember from days past taht you couldn't fit a pci card in your rig.
    New System in progress:
    M10k
    Phaze TD1500 ~> Dynaudio MD130
    Phaze TD1500 ~> Seas g18rnx/p
    Zapco Ref 500.1 ~ 12" tc-9
    Behringer DCX2496 ~ Envision Electronics psu
    Transflective Xenarc

    My Car Pc Install
    My Boat Pc worklog

  7. #17
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    that's the fun part...lol

    In the VWs, the back seat is a 60/40 split. Since we're looking at having the interior redone, I'm thinking about remaking the cushion part of the 60 side, to a 40 and placing the case for this pc in the middle...since no one ever sits there. If it's in a case it will also be able to take things being thrown on it, etc.
    Jan Bennett
    FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

    Please post on the forums! Chances are, someone else has or will have the same questions as you!

  8. #18
    Car Audio Moderator durwood's Avatar
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    Quote Originally Posted by RedGTiVR6 View Post
    sure, it's a bit pricey, but just check my signiture for my thoughts on that.
    That's cheap

    The ones I was looking at were ~$12 each from digikey. (I should have reworded my question but you answered it anyway...I meant how did you decide to use the ones you picked? But you said it was linked from the Auzentech site so question answered. Thanks


    Cool idea with the seat. I now have to relocate mine from under the seat to the trunk. I know how much you liked my mounting location before... J/K. I am a little worried about mounting a hard drive near my structrual bracing for the suspension. It's not exactly a cushy ride back there.

  9. #19
    Car Audio Moderator durwood's Avatar
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    Have a look at this list of opamps. It all personal opinion but can give you more options: The OPA627 and AD843 are very close contenders (but only single opamps). The OP134/2134 are not high on his list.

    http://tangentsoft.net/audio/opamps.html

  10. #20
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    Yes, I've seen that list as well.

    I also have this email from a guy on another forum that might be beneficial to some:

    Jan,

    I'll start by telling you, I'm an electronic design engineer
    specializing in audio. I'm also a musician so I have at least some
    idea of what I'm hearing from a musical standpoint.

    I believe the stock amps in the Auzentech X-Meridian are called
    S4580P. Some of the amps on your list may sound better than the 4580.
    It's a derivative design of some earlier amps in the series. The
    letters at the start are often specific to the manufacturer, but the
    model is 4580. The same amp from is made by NJR (New Japan Radio),
    aka JRC (Japan Radio Co.).

    http://www.datasheetcatalog.com/data.../NJM4580.shtml

    Here's the specs for the S4580P:

    http://www.auk.co.kr/file/product/product/S4580P.pdf

    Neither manufacturer specs noise voltage correctly, although it can be
    calculated from the spec they give. A well spec'd amp should give the
    figure in nanovolts per root hertz (nv/√Hz). Their spec is 0.8 μV over
    a 30 KHz bandwidth. Dividing that number by the square root of 30,000
    gives you 4.62 nv/√Hz, which isn't bad.

    The slew rate (the maximum rate at which the amp can go from positive
    to negative or from negative to positive) only 5 volts/μs, which isn't
    bad, as long as you're not running on +/- 15 volt supplies, but other
    amps are much better.

    Two inexpensive amps you could try would be National LF353 and Texas
    Instruments (TI) or Phillips NE5532. Of the two, the LF353 is noiser
    than the NE5532, but I like the overall sound of the LF353 better. The
    noise of the amp, itself may or may not make a difference, depending
    on how much gain it takes and how much noise is present in the signal,
    itself.

    Note that parts with the same numbers from different manufacturers are
    NOT necessarily exactly the same circuits, and even they are, one
    maker's part may not sound or work as good as another's with the same
    number. Many manufacturer's re-label their own product designs having
    closely similar specs as a second source for a popular product. For
    example, TI is the originator of the TL070 series of amps (TL071, 72
    and 74 single dual and quad amps). If you order TL072 from National,
    they will send you a LF353 or LF412 (same as amp as the current LF353)
    marked as LF353, and if you order LF353 from TI, they will send you a
    TL072 marked as an LF353. They are close enough that it doesn't
    matter in many applications, but different enough that they can sound
    or work differently in some critical circuits. You have to test each
    vendors' products individually for your applications.

    Of the new amps on your list, I'm most interested in National
    Semiconductor's new op-amp targeted for audio, LM4562 and
    TI/Burr-Brown's OPA134 family, including the dual amp, OPA2134. The
    LM4562 has great specs all around, including being quieter than the
    4580 but I've never had a chance to listen to it or test it for
    stability, etc. It could be a winner if it is used in the microphone
    preamp section. The OPA2134 is a FET input stage, which could be to
    its advantage. Although not as quiet as the LM4562, it likewise has
    great specs and could be a winner for applications where the noise of
    the circuit is not the dominant consideration.

    What's more important is, since they[re pluggable, these amps should
    just plug and play. If it were me, I'd be go for it and try for
    better sounding amps than the 4580. Setting up a test for more than
    just subjective impressions could be difficult unless you have a good,
    neutral test circuit where you can switch the same signal source
    between two identical circuits with the only the difference being the
    op-amps.

    LM4562

    http://www.national.com/ds/LM/LM4562.pdf

    OPA132, 2132, 4132

    http://www.ti.com/lit/gpn/opa132.pdf

    OPA134, 2134, 4134

    http://www.ti.com/lit/gpn/opa134.pdf

    Both amps have the same key specs:

    Slew rate: 20 volts/μs
    Noise voltage: 8 nv/√Hz at 1 KHz
    Gain bandwidth product: 8 MHz.

    They may or may not be the same amp. The 134 family specs appear to be
    more oriented toward audio, while the 132 family gives more
    conventional engineering specs, but so many of their graphs and scope
    photos are exactly the same that I think they are the same part
    possibly with different guaranteed specs related to the application.

    I e-mailed TI to ask their tech support people for more info about the
    differences. I want to know, as well.

    I haven't had the opportunity to test or listen to the OPA2132 or the
    National LM4562, and the specs for both are great, but some amps with
    great specs still sound bad in actual use for reasons too technical to
    get into at length. Both should work better than the LF353 if the
    gain exceeds 12 dB, or if it's being used in some other critical
    applications, such as a filter (equalizer) circuit, but I can't say
    anything definite without more info.

    After that, there are still more considerations in choosing the right
    amp. For example, a great noise spec is meaningless if, in the actual
    application, the noise from the signal source (the program material
    and all the stages preceding the circuitry) exceeds the noise
    contribution of the stage under evaluation.

    Some of the other amps you mentioned:

    Linear Tech's LT1024 is a SINGLE amp in an 8 pin package. It's an
    excellent, if somewhat pricey, amp but it won't fit in the socket for
    an DUAL amp without an adapter, and that's FAR more work than it's
    worth considering all the good alternatives that will just plug in.
    The same applies to any other single amp on your list.

    The original NE5532 originates from Philips/Signetics, noted above, is
    a dual of their part number NE5534 that is slowed down to maintain
    stability without the optional external compensation needed in some
    applications because there aren't enough pins (2 per channel)
    available on an 8 pin package to connect to the external components
    Other amps with the numbers 5532 and 5534 are second source copies or
    near copies of these parts. Without evaluation, the only other
    manufacturer I trust for them are Texas Instruments and possibly
    Fairchild.

    They are OK, but not great sounding audio amps. The 5534 (single)
    tends to sound brittle. The slower 5532 just sounds... well...
    slower. However, for a jellybean component, they have good noise
    performance, and they could be the best sounding part for an
    inexpensive product design. I would not consider them for a high end
    product where absolute cost was not the first consideration.

    To summarize, I think you can do better than the 4560 that come stock
    in the X-Meridian. I can't say whether the LF353 would sound as good
    as I would hope without knowing the circuit and the component values
    around it. Any op-amp good enough to give excellent performance can
    also be disappointing due to poor circuit design and layout, so it
    also depends on the skill of the designer, and it still gets down to
    listening to it in a specific application.

    I wish I could help you more, but you're still down to listening
    tests. You can measure stuff all day, but it still gets down to
    enjoying what you're hearing.

    If your competition brings you to developing commercial products, I
    would be glad to discuss providing professional design services for
    your products. If you are doing this for the competition without
    commercial goals, I hope the above info is helpful, and I wish you the
    best of luck. I live in the San Fernando Valley area of L.A. Ca.
    I'll be glad to give you more contact info if you're interested.

    Regards,


    Harvey Rubens
    Jan Bennett
    FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

    Please post on the forums! Chances are, someone else has or will have the same questions as you!

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