For my QA400 I'm now also experimenting with Windows 8.1 installed on an external hard drive and booted on a USB 3.0 port. It seems to work quite well and isn't as slow as expected. I have it on an ex laptop 2.5" drive and will move it to an ssd next week.
For those interested you can buy an install key on eBay at present for just a few dollars... They say they are from decommissioned machines. Download the isos from Microsoft and you're up and running.
For those interested you can buy an install key on eBay at present for just a few dollars... They say they are from decommissioned machines. Download the isos from Microsoft and you're up and running.
It can work but it's still a mixed bag. I was able to stream 1080p HDTV over a USB CableCard tuner via Windows Media Center in VMWare but had some lip sync issues.
The QA40x is more likely to work precisely because it's not a USB Audio Class device. I find most things that are using bulk or interrupt transfers work well in VMWare because they are common use cases (Mass Storage, HID). Isochronous is always the flakiest.
For those having problems with USB dropouts. Download LatencyMon (free) and run that plus the In-Depth Latency Checker and run the Tight Loop Latency Tests. If you can't stay in the green for these you are going to have problems with timely USB I/O. It should help you pinpoint the driver or service causing the issue, but sometimes it's not easy.
For Windows only I use EasyBCD - NeoSmart Technologies which configured the Windows bootloader which does the work. You don't need it but life is easier with it. Systems with Linux I use Grub.
Hopefully this is the right place in this thread as this is my first DIY Audio post...
I have version 1.615 for my QA401. I've tried to create my own weighting table for ITU-R 468. It tells me that it's not loaded. The included RIAA weighting works fine, even if I modify it. The last time I tried, I got an error that has been logged and I can attach if needed. It seems straight forward. Am I doing something wrong or have I discovered a bug?
I have version 1.615 for my QA401. I've tried to create my own weighting table for ITU-R 468. It tells me that it's not loaded. The included RIAA weighting works fine, even if I modify it. The last time I tried, I got an error that has been logged and I can attach if needed. It seems straight forward. Am I doing something wrong or have I discovered a bug?
We used to be able to do that for our selves before Microsoft hid it with later Windows versions. Now we have to buy it. Oh well. Both QA400 and the 401 work fine for any new computer I have used it with (i7).
THx-RNMarsh
I have found the VMware Player config mentioned above not to be as bulletproof as I first thought. I now run my QA400 by booting a Windows 8.1 machine on a usb ssd. It boots in about 10 seconds and works perfectly. Buy a Windows 8.1 key via ebay and obtain the iso file from Microsoft. That cost me about 10 bucks.
As others here have experienced, my QA400 does not work properly with the latest W10 1803 update. I have not tried the VMware or a dual boot pc options yet. I am thinking of just updating to QA401.
Before I order the QA401 I wanted to see if anyone here is experiencing problems using the latest W10 1803 OS and the QA401.
Before I order the QA401 I wanted to see if anyone here is experiencing problems using the latest W10 1803 OS and the QA401.
Well, as other here have experienced, my QA400 no longer works after the Windows 10-1803 update.
I am thinking of running a dual boot Windows 10 & Windows 7. It is not clear (to me) on the QA website whether or not the latest QA400 software will work with Windows 7.
Anyone have any trouble running the QA400 software with Windows 7 OS?
I am thinking of running a dual boot Windows 10 & Windows 7. It is not clear (to me) on the QA website whether or not the latest QA400 software will work with Windows 7.
Anyone have any trouble running the QA400 software with Windows 7 OS?
I just ordered the QA401, anxiously awaiting the delivery. Curious, I currently run two Dale 8 ohm 250W 1% non-inductive resistors in my bench dummy load. I currently us an HP 8903B that I simply feed via a BNC cable tapped across the 8 ohm load with a switch to vary between L & R channels. I mostly use it on vintage stereo gear I've restored. Time for something new though...
Anyways, how are you guys connecting the QA401 to your dummy load? What are you using for a dummy load? Using any sort of resistor divider network as an attenuator?
Just curious what others may have already figured out worked well. Thanks in advance for your input Mark
Anyways, how are you guys connecting the QA401 to your dummy load? What are you using for a dummy load? Using any sort of resistor divider network as an attenuator?
Just curious what others may have already figured out worked well. Thanks in advance for your input Mark
Hi blueglow,
I use the same resistors that you do. I recently bought an RTX 6001 and it has balanced inputs. This allows me to not worry about ground loops due to connecting wire between the loads.
Before doing this, I would measure one channel at a time using an HP 339A. Connecting the load grounds together is bad news. Having that connection made inside a piece of test equipment is even worse news.
As for attenuators, you can make one from resistors, but you will have to compensate them much like an oscilloscope probe must be.
-Chris
I use the same resistors that you do. I recently bought an RTX 6001 and it has balanced inputs. This allows me to not worry about ground loops due to connecting wire between the loads.
Before doing this, I would measure one channel at a time using an HP 339A. Connecting the load grounds together is bad news. Having that connection made inside a piece of test equipment is even worse news.
As for attenuators, you can make one from resistors, but you will have to compensate them much like an oscilloscope probe must be.
-Chris
Thanks Mark but I got it working.
Well I am happy to report that I did set up a dual boot laptop (Win10 & Win7). The Q400 runs perfectly in Win7. I decided to install all my bench programs in the Win7 partition. ARTA and Pete Millett's HP8903 Analyzer Software. I will continue to use the Win10 partition for web browsing and email.
Input attenuator-
First check the max input for the QA401 @ 56V P-P or 28V peak to confirm that is not enough for the amp you want to test. The input is full differential but the peak with respect to the ground at the input is 28V. if you are using 8 Ohm loads (and I see no reason why they need to be exceptionally non-inductive but that is a separate discussion) you could build an attenuator using a 720 Ohm resistor and an 80 Ohm resistor. You would not need any compensation for this and any frequency this system will operate at. The 20 dB (10X) attenuation will make the arithmetic pretty easy from there.Actually I would use 2 360 Ohm resistors from each end of the load with the 80 Ohm resistor in the middle so BTL or single ended will work fine.
Matt at QA is working on an interesting load box. Since its controlled by the software it may be able to do more.
First check the max input for the QA401 @ 56V P-P or 28V peak to confirm that is not enough for the amp you want to test. The input is full differential but the peak with respect to the ground at the input is 28V. if you are using 8 Ohm loads (and I see no reason why they need to be exceptionally non-inductive but that is a separate discussion) you could build an attenuator using a 720 Ohm resistor and an 80 Ohm resistor. You would not need any compensation for this and any frequency this system will operate at. The 20 dB (10X) attenuation will make the arithmetic pretty easy from there.Actually I would use 2 360 Ohm resistors from each end of the load with the 80 Ohm resistor in the middle so BTL or single ended will work fine.
Matt at QA is working on an interesting load box. Since its controlled by the software it may be able to do more.
Hi Demian,
Good to know. I was working with sound cards whose impedance was (very approximately) 10 K. The network did require compensation due to the higher resistances involved. I was pretty surprised at ow much compensation was needed due to the high input capacitance on some sound cards.
-Chris
Good to know. I was working with sound cards whose impedance was (very approximately) 10 K. The network did require compensation due to the higher resistances involved. I was pretty surprised at ow much compensation was needed due to the high input capacitance on some sound cards.
-Chris
Have you read this blog post on their site about testing a D-amp with a QA401?
First Look: Evaluating Class D Power Amps with the QA401 – QuantAsylum