Sound quality problems with xDax, Loopback and a MacBook Air

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  • Updated 1 year ago
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TIme to look for some help from the community. I'm a long-time Mac user, and was thrilled to find out it would be possible to use xDax on a Mac for digital programs with my new 6600M (part of the reason I decided to go with the Flex instead of the new Icom).

A few days after receiving my 6600M, I loaded all the appropriate software (dogparkSDR, xDax, xCat, Loopback, Fldigi and WSJT-X) on my MacBook Air. First try was using Fldigi for my favorite digital chat mode, FSQ.

I found that decoding was not particularly effective. The individual tones appeared to be slightly horizontally stretched or elongated, not so bad that strong signals were not decoded, but signals that I was easily decoding with my K3 / SignaLink / Linux setup were not decoded. Thinking the problem was the fact I was running too much on the MacBook, I connected the 6600M front panel instead of dogparkSDR, and only ran xDax and xCat with Fldigi on the MacBook. Still no joy - the tones making up the signal were still distorted.

So I loaded up a Windows 10 laptop with Dax, Cat and Fldigi to try that in exactly the way I set up the MacBook - perfect decode, great signal quality, no distortion. So the problem is the Mac environment, not the radio.

Now the questions about my Mac setup:

I am using the Rogue Amoeba's Loopback software to create two pass-through devices, one for input, one for output. One I connect to Dax Rx, the other to Dax Tx, then I connect the corresponding devices to Fldigi's input and output respectively.

Am I doing this right? Anyone experience problems with Loopback and xDax on MacOS 10.13? (Other than the annoying lack of rig control support for the 6600, forcing use of COM port emulation in Cat.)

Thanks for any input. By the way, I love the 6600M, but have discovered if I'm going to use a Windows laptop as a remote, it needs a lot more horsepower than the one I have :-) It appears dogparkSDR and xDax are less load on the Mac hardware.

Ted VE3TRQ .
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Ted VE3TRQ

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Posted 1 year ago

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George Molnar, KF2T, Elmer

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Hi, Ted. Have run that setup on a Macbook Air and a Mac mini, both very successfully. Check to see if your Loopback-created audio devices are running at 48,000 Hz sampling, and that only your rig application (Dogpark SDR) and digimodes applications are assigned to the devices. Make sure the levels are okay, too -- the slider in xDAX is pretty useful.

For rig control, recent versions of Hamlib should work using 127.0.0.1:xxxx as the device, with the port being what you've defined in xCAT RigCtl setting. You may need to check "mask 6300" in the xCAT settings; it reports the rig as a 6500 to Hamlib.

Good luck!
(Edited)
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Burch - K4QXX

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I know this won't help but I have the same problem running my FT-991 and Icom-7300 on my Mac (via USB cable).  I can decode fine but when I transmit, it sounds garbled and people can't decode my signal.

I also run the loopback software with Dogpark on my Macbook Pro and mini-mac.  I did have to play with the loopback software a bit to get it to work correctly.  I will look at the settings when I get home from work.

Burch
K4QXX
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Michael Walker, Employee

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Hi Ted

 You don't need much Windows HorsePower.  Just about any computer that was purchased in the last 3-4 years is plenty fast enough.  I recommend what ever is on sale at Cosctco.  :)

If you are seeing slowdowns. I would start with turning on your AntiVirus just as a test.  Some AV's can consume up to 50% of all your available resources.  

Also, hard drives that are starting to fail look a lot like a slow computer but what happens is the hard drive is in a constant state of repair.  And, to make it more complicated, you can't tell this is going on without some special tools like Spinrite.

Mike
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Ted VE3TRQ

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Thanks for your comments, Michael. You are exactly right about the source of most of the extra overhead. Windows defender was the worst culprit, and that plus a couple of system processes were pushing the CPU usage to 100%. Without those processes, the Flex s/w was using about 50%, plus or minus.

Unfortunately, the system processes I have no (or little) control over, and I refuse to run a Windows machine without at least _some_ protection. Leaves me in the position of buying a more expensive Windows laptop if I pursue using Windows. My preference is to use the Windows laptop only to do radio updates, and performance is not an issue there. The MacBook Air appears to handle the load of the digital apps plus dogparksdr and xDax just fine.

Just need to work through the sound quality issues (and finally update my iMac to Sierra or High Sierra, thereby losing access to my venerable PhotoShop CS5 :-)

Ted
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Michael Walker, Employee

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I run my remote computers without any AV as it just wasted needed.  Windows Defender shouldn't take up that much resource, so there is something else going on.  Don't forget that any file you touch on your computer must first be handled by AV to make sure it is clean.   Computer available memory and hard disk speed are direct impact of computer speed.  Having at least 8G is a requirement.  
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Bob- W5TX

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Ted, not sure why you have to give up Photoshop CS5? Run on both Sierra and High Sierra.
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Ted VE3TRQ

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Oh? I'm really happy to hear that. I had been told that CS5 would not run under High Sierra. That means I can update the iMac to run Loopback and xDax/xCat! MacBook Air for remote, iMac with two monitors for local.
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K3SF

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one thought demo vs paid version loopback

although you can download and use loopback, the unpaid/demo version injects garbled sound every few seconds after 20 second on initial use.  i have seen that with the demo version.  

i used the demo version to convince myself i could easily build virtual audio cables and experienced the garble sound.

i now run the paid version and have had no issues with  my flex 6600M running dpsdr (b46) with 4 slices with xcat and xdax, 4 instances of wsjtx as well as jtbridge and mldx. The most cpu intense process is jtbridge which does a lotta db hits against mldx and at time has hit 100% cpu utilization just by jtbridge.

bottomline, if using demo version expect garble audio, if using paid then should  beno problem.

another thing to check is the setup making sure to do passthru

i have run this on macbookpro (2011 w 8gb ram and 1 TB SSD)
AND
i7 mac mini and i5 mac mini

hope this might help



 













(Edited)
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Ted VE3TRQ

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Official Response
Thank you all, especially Paul and George. Bob also for the tip on High Sierra and PhotoShop CS5.

I reinstalled everything all over again (I do have the paid version of Loopback :-), reconfigured everything several times over and still had bad noise in the output and slightly distorted input. Rebooted the MacBook Air one more time, AND ALL IS GOOD! Paul's (K3SF) posting confirmed that I had it set up correctly.

Superb low signal level performance with FSQ - the Flex digital audio really outperforms the SignaLink USB and analog audio from the K3.

This community is one of the better features of owning a Flex.

Ted
(Edited)