Related Manuals for QuantAsylum QA451
Summary of Contents for QuantAsylum QA451
- Page 1 QuantAsylum QA451 User’s Manual QuantAsylum QA451(B) User’s Manual Programmable 4/8 Ohm Load SW Release 1.4 October 2023 Page 1...
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Page 2: Safety Notice
Product Notice The QA451 and QA451B are the same product, using the same software. There is a difference in current sensing accuracy between the two products used on the DC Switch + Sense port. This port is for use in measuring the current consumption of an amplifier board. -
Page 3: Table Of Contents
Important Things to Understand ........................5 Ground Reference ............................. 5 Current Sense Inputs ..........................5 Load Inputs ..............................5 QA451 Programmable Load Features ......................6 QA451 Front Panel ............................6 Front Panel Summary..........................6 LEDs ................................6 Current Sense Inputs ..........................7 DUT Power Soft Start .......................... - Page 4 QuantAsylum QA451 User’s Manual Tractor ..............................19 Page 4...
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Page 5: Legal
You should measure, and from time to time confirm, that the BNC grounds are electrically isolated from the USB grounds. This isolation is limited to 50V. Do not connect the QA451 to a product that has its ground reference more than +/-50V from the PC ground. -
Page 6: Qa451 Programmable Load Features
When open, 4 or 8 ohm loads are selected, attenuated (by 12 dB) versions of the speaker signals will appear at the BNC outputs of the QA451. For example, the L- speaker input will appear at the L- BNC output, attenuated by 6 dB. -
Page 7: Current Sense Inputs
If both the 8 and 4 ohm LEDs are flashing, then it means the QA451 has reached a thermal limit. This is not harmful to the QA451. When this happens, the QA451 will open the relays automatically and ensure the load inputs are removed from the internal load resistors. -
Page 8: Load Inputs
QA451. Given the QA451 maximum ratings, the voltage on the load inputs must not exceed 50VAC RMS The maximum currents at the QA451 maximum ratings occur when the load is set to 4 ohms at 300W. This corresponds to an 8.66A RMS current. -
Page 9: Qa451 Software
If you press the “8 Ohms” button, you will hear a “click” from the QA451 relays and the application will report the 8 ohm load is active as shown below. At this point, you can use a DVM to measure across the L+ and L- Load Input pins and confirm that 8 ohms is being presented. -
Page 10: Application Temperature Sensing
DUT Power The DUT POWER button is used to the turn on the high-side PMOS in the QA451. When enabled, the S+ and S- will be connected by a low impedance of 25 mOhms or so. This is Rds(on) of the high-side PMOS pass device. - Page 11 You can see the REST API published by the QA451 by going to your browser and opening the url (the same URL is used for the QA450 and...
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Page 12: Qa451 Load Resistors
15% as the backplate temperature reaches 50C. If the resistors are near room temperature and the QA451 is configured for 4 ohms (8 resistors), then you can hit the load with 8 * 25 = 200W for several seconds until the thermal protection kicks in. The temperature will quickly rise over several seconds and further de-rating will be necessary as it increases. -
Page 13: Audio Bursts
4 ohms provides a reasonable reliability margin. This is an 8K FFT. The temp sensing on the QA451 has a lag. If the load resistors are hit with 800W for 100 mS, then the temperature of the resistor active area will climb very quickly while the temp sensor located 2-3 mm away from the resistor body will remain unchanged. -
Page 14: Thermal Considerations
The power levels of these tests may be anywhere from milliwatts to hundreds of watts. The average power you subject the QA451 to must be around 5-10W or so. That is, if you compute the watt*second product of your tests, and then divide that by your total test time (including operator change over to the next amplifier), then the average should be around 5-10W to ensure continuous operation. -
Page 15: Impact Of Switchover
1.5W. In summary, you need to plan your thermal budget ahead of time to ensure the QA451 can meet your needs. Hitting the thermal targets above will ensure continuous operation without having to wait for cooldowns. -
Page 16: Appendix I: Typical Connection Diagram
QuantAsylum QA451 User’s Manual Appendix I: Typical Connection Diagram Page 16... -
Page 17: Appendix Ii: Qa451 Specifications
When “open” the QA451 will present a ~10K load to the DUT on the Load Inputs. Some Class D amplifiers that are powered from a single rail will “idle” at a DC voltage that is half of the supply rail. For example, a Class D amp running at 50V will have outputs that idle at 25V DC. - Page 18 QuantAsylum QA451 User’s Manual Page 18...
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Page 19: Appendix Iii: Interfacing With Other Applications
Tractor treats the QA450 and the QA451 as the same hardware. When you specify “Pre-analyzer Input Gain” in Tractor (example below), you will want to specify -12 dB if you are using the QA451, and -6 dB if you are using the QA450. - Page 20 QuantAsylum QA451 User’s Manual Page 20...
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