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Connecting Dynaudio BM5A Active Speakers to MBP

Discussion in 'Digital Audio' started by raviba, Jun 14, 2013.

  1. macrumors newbie

    I now connect Audioengine A2 speakers to my MBP using the single pin TRS audio output. Alternatively this system also works when the output from an Airport Express is connected to the A2 speakers .

    When I bought a pair of Dynaudio BM5A active speakers, the manufacturer said that I have to use a "bump box" to raise the level and impedance to connect the speakers to the MBP.

    I am trying to avoid a rat's nest of wiring. Will the BM5A speakers not work if connected without a bump box or will the sound be of inferior fidelity? In other words, is a bump box a must?
  2. macrumors G4

    Try using the input sensitivity setting first. Then if you don't like the sound get an external preamplifier.

    But for best sound quality you MUST have some kind of analog volume control. Never use the digital control with the mouse if the goal is the best sound. It ALWAYS deduces the dynamic range of the sound, always. It is a law is physics the engineers can't get around
    Reason is that the step size of the DAC remains fixed but the maximum amplitude changes. So you loose "bits". Keep the sliders are max and adjust with an analog knob.

    Of maybe you don't care? The compromise is some setting were the slider as high as it can be.

    All that said, in terms for sond quality per $$ spent, speaker placement (using a stack of bricks for stands and room treatments will give yu thebest return on investment. Cost can be very low if you don't care about looks and style.
  3. macrumors newbie

    Input Level

    Thanks; you are on the button. The speakers provide for input level from -1- dB to +4 dB to accommodate high and low output levels f the source. I am pleased with the sound at +4 dB. I feel the sound could be louder, but as you say, I'll have to use a preamp or a bum box, which will lead to wire clutter. Your comment is much appreciated.
  4. macrumors newbie

    Connecting Dynaudio BM5A speakers to computer - use of Audioengine DAC D1

    ChrisA or others, please comment:

    Instead of a bump box, what if I use a Digital Audio Converter (DAC)? Audioengine makes a medium price DAC called D1, which is USB-powered. Would such a DAC adjust for level and impedance? The D1 has a knob for adjusting volume.

    Am I right in thinking that an MBP and Airport Express (AX) have some kind of a DAC in them? Connecting the external DAC will bypass the DAC in the computer or AX, right? Thanks.
  5. macrumors regular

    I can vouch for the Audio Engine D1, I have a 2011 Mac Mini and use the optical out (Mini volume at max) into the D1, then to a Vincent SV-400 integrated amp paired with passive PSB Image B6 bookshelf speakers.
    The D1 also doubles as a headphone amp, although this brings into play where to set volume on the D1 before the integrated amp, I kept playing with that.
    24/96 files from HD Tracks sound fantastic!
    Hope that helps.
  6. ChrisA, Jun 16, 2013
    Last edited: Jun 16, 2013

    macrumors G4

    Of course the Mac and AP has a built in DAC. How else could they work? The problem with it is that it lacks an analog gain control. There is no volume knob.

    If you want an USB audio interface the best place to shop is any of the stores that sell to musicians and recording engineers. I have This little box's big brother, the output sections are the same.
    It is more than you need for HiFi listening. But maybe some day you might want to record something? Or use a measurement microphone to measure your systems audio performance.

    Be sure and watch the fist video all the way, read the captions. It is well built.

    The little audio box has separate volume controls for headphone and monitor speakers and balance outputs. not bad for the price.

    The D1 looks to be about the same thing but with less functions and I bet you can't run a truck over it. That is kind of the difference between gear sold to engineers and to "audiophiles". The engineers get better stuff for less money.

    For is a fire wire version of this for another $100. Ithas a stronger headphone amp because USB is power limited. The FW version has the option to run off mains or be bus powered.
  7. macrumors newbie

    Connecting Dynaudio BM5A Active Speakers to MBP

    ChrisA, Thanks for the generous and expert advice. Have always admired engineers for their attention to good design and performance.

    Geez, they truly run a truck over this item! Remarkable. Just ordered one for my computer and will order one more for the stereo system in my living room which is connected to an Airport Express.
  8. macrumors 6502a

    I've read that the volume control in iTunes works at 32 bits, giving you 96dB of attenuation before you start eating into the dynamic range of 16-bit audio...
  9. macrumors newbie

    Connecting Dynaudio BM5A Active Speakers to MBP

    All: Just an update - the Audiobox USB is really cat's whiskers!

    Set up: from the MBP to the Audiobox using the USB output; Dynaudio BM5A speakers connected to Audiobox USB with TRS-XLR cables from B&H audiovisual. Set the Mixer on the Audiobox to full Playback. Sound from the speakers is significantly better with the Audiobox. Really great clarity and volume of sound from the speakers!

    By the way, Sweetwater is a great outfit, with good customer support.


    I also wanted to connect an Audiobox USB to to an Airport Express which is connected to a Cary SL98 preamp/ McIntosh MC501 amps/Legacy Audio speakers in my living room. I could not find a way of doing such a connection. So, I will be using an Audioengine D1 for this purpose. My Airport Express dates to 2006 or so, but it has an audio out port which is both optical and analog. I am connecting it to the D1 by using a minitoslink/toslink cable, and then by RCA cables to the preamp.

    How to test if the Airport Express optical out is working : send signal from computer to Airport Express. If optical is working, you will see a red light in the audio out port.
  10. ChrisA, Jun 28, 2013
    Last edited: Jun 28, 2013

    macrumors G4

    How can that possibly be? Think of the numbers that the DAC must be outputting for a full volume sine wave. OK, they must range from 0 to 64,536.

    Not lets turn the volume down by 6dB (to 1/4 of the volume) we now have number that range from 0 to 16,384

    There is not way out of it if there is no attenuation AFTER the sac you will loose dynamic range. If those digital sliders controlled a switchable attenuator then there would be no issue. But I don't think it works like that

    If internal processing is done in 32 bits what that address is to processing loss or "round off" noise. That is a different issue. And yes to go have lots of of extra bits in tern ally. That is a good reason to always record with 24 bits But the fink volume control is just a divider
  11. macrumors newbie

    Connecting the Audiobox USB to the Dynaudio BM5A speakers has been a success. Fantastic sound.

    Now, for my living room stereo: I am trying connect the optical output on the Airport Express to the Audiobox USB. Is there any kind of cable that has an optical input on one end and a USB connection on the other end? Thanks.
  12. macrumors newbie

    Toslink to USB connection

    Does anybody know of a cable that would enable me to connect the optical out of an Airport Express to an Audiobox USB , which has only a USB input?Thanks.
  13. macrumors 6502a

    The 32-bit volume control thing is just something I've heard on a few occasions, so I can't vouch for it, but I'd imagine what happens is iTunes converts the audio to 32 bits, before dithering to 24 bits to hand off to the DAC (assuming most modern DACs to be 24-bit). This way you'd be able to knock the volume down by 48dB and still be left with 65,536 un-truncated (albeit dithered) values.
  14. macrumors newbie

    Audiobox USB

    ChrisA's suggestion of using a Presonus Audiobox USB to connect my MBP to Dynaudio powered speakers has served me well.

    The AB appears to be well known to music-makers. Obviously, I am using only a small part of its capabilities in using the DAC. Not often mentioned is that the DAC chip in the AB is a Cirrus Logic CS4270. Tech details are in this link:


    I wanted to use the AB to connect to Airport Express . I have reasonably established that it is not possible to connect it to the Toslink optical output of an Airport Express. I have informed Presonus that they would add value to the AB if they could provide an optical input. However, it seems they are not really into elementary DAC equipment for use by beginners like me.

    ChrisA comments below about the difference between equipment pros use and the prosumer world. AB's sturdy build quality and technical excellence have demonstrated those well. I stand usefully educated.

    I tried using the Audioengine D1 instead of the AB to connect to the Airport Express, but even though both are USB-powered, the D1 had weaker audio gain. I am therefore considering a Cambridge Audio Dacmagic Plus or an Oppo BDP-105. The 105 may be an overkill, but might give me greater utility.

    Thanks to all for the comments and suggestions.

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