Any updates on QA403 replacement?

Are there any updates on the replacement for the QA403 if this is still planned? Or is EVERYTHING still uncertain because of the semiconductor shortages? Thanks.

Hi @djsb, there are no updates at this point for the QA403, unfortunately.

I think at this point the QA404 will be out before the next batch of QA403. The QA404 doesn’t have isolation, which is the blocker for the QA403 at this point. I wish the news were better on the QA403.

Will the QA404 PCB have pads so that isolators can be retrofitted if/when they become available?

Hi @aaa, no it will not. It’s not just the digital isolators that are unavailable, it’s the push-pull transformer drivers.

I know component procurement is (still) hard these days, but is the replacement of a digital isolator really that complicated?The DC/DC converter could have been replaced by a simple external power supply. Is it really worth the risk of totally new design?

I do this component replacement task for many years in medical electronics. Most of the time due to obsolences and the last two years because of shortages. Yes, it is annoying but feasible.

A few months back Ford had 45K trucks sitting in lots waiting for parts. GM has 95K cars sitting in lots waiting for parts. Of course QuantAsylum is miniscule compared to the Ford, but the problem is even harder because strategically we’re nothing compared to a Ford. We get whatever Ford et al doesn’t need. The last in line.

The issue isn’t that we just need to find a substitute. It’s that there are NO substitutes available. And so, that means a sizable re-design. Now, the reason the parts nobody can get are unavailable is because they performed a unique task. If that functionality could be easily replaced it would be.

An external supply still requires the digital isolation, and even then external supplies (such as USB 5V) are really bad from a noise standpoint (mostly powerline hum).

I really do wish the situation was better. Sorry it’s not. It’s frustrating all the way around.

Matt, what does the outlook for the QA404 look like at this point in time, and is the QA451 going to be available any time soon??

Are you waiting for parts for ALL your systems???

Is anything for sale???

Hi @bonzoro, yes, nothing is being sold right now, but the QA451 replacements have been built and the QA461 (the follow-on to the QA460) has all the parts and is ready to go. The QA460 had an output current sense port that was a differential output across a 0.02ohm resistor in the output path. The QA461 moves that to a single-ended output with a gain of 50 difference amp, so you still have 0.02 ohms of output Z, but it’s 1 ohm effective, which helps with measuring impedance of higher-z components. The differential 0.02 ohm combined with the CMRR of the QA40x let you measure component impedances up to about 1K or so. The effective 1 ohm output Z will extend that considerably.

I think the QA404 will be ready in Feb or March next year.

So, the QA-451 replacement (QA-451X???) have been built but it’s not for sale???

Hi @Bonzoro, Yes, it’s a QA451B I think, because it has less resolution in the DC current sensing (in case you are testing amp efficiency). This was compromise because the dual current sensors used on the QA451 wasn’t available and had to be replaced with a single current sensor. I think the QA451 DC current sense path is something like 8 mA of resolution, and the QA451B has 16 mA of resolution, or something similar. If you aren’t interested in the higher resolution measurement of the amp DC supply, then the difference between the QA451 and QA451B is nothing–they are the same. And if you are interested in the efficiency of higher-power amps (>20W or so) then the lesser resolution isn’t that big a deal because the difference between 2.000A or 2.008A current sense isn’t that big of a deal when talking about 20W. However, if you are interested in the efficiency of a 5V 1W amp, then the QA451 vs QA451B starts to matter.

In any case, I think the aim is to have these 3 products ready to go all at once.

So, let me get this straight. You are not selling anything until you have other items for sale???

With the 403 out till… never
the 404 out till maybe next spring

you aint selling ANYTHING till some other things, which may or may not come to fruition any time soon are READY


That really IS about the dumbest thing I EVER heard.

That’s like Walmart not opening the doors for Christmas shopping because there is still more 18 wheelers waiting to be unloaded.

Your business model stinks.

Hi Bonzoro, thanks for your vote of confidence :wink: If we had 6 of 7 (or even 3 of 7) products in stock, of course we’d be selling. But 1 out of 7, I’m not sure. If Walmart had 28 aisles and 4 were open and the rest were empty, do you think they’d be open? I’ll bet not.

Anyway, I guess it’s debatable whether we sell QA451B now, or offer them when we have the QA404. I’d prefer the latter since they are often bought together.

Hello Matt, above you have mentioned the QA461. Will it have the same spec as the QA460 with a different power supply? Or are the specs different? I hope the new product line up will be less depending on specialized components so your business is more resilient to shortage of products from certain suppliers. I’m looking forward to your new products.

Since I had to buy an old Analyzer, and there are no Programmable Loads on the market, it puts me in a dilemma that I’m sure concerns you in the least but when you said you had QA-451B’s ready but sitting on them, it makes me scratch my head. I just think your choice of saying they are ready but you won’t sell me one is BS. But, it is YOUR company and the choice is yours to make and I have to live with it. All I can do is HOPE Santa has heard me and brings me one for Christmas whether it be this one or the next one. That wasn’t meant to sting, the last I read about the situation on the QA-451 was:

June 2021: The QA451 is on backorder, with new order arrival TBD. The issue, as with our other products, is the silicon shortage discussed here.

It’s hard to give a "Vote of Confidence :wink: " with an update from a year and a half ago. How about just sending me an invoice for a 451B and I won’t tell a soul. Sorry Matt, just frustration talking. :slight_smile:

Yes, same specs as QA460 (and same brick power supply). The only change is the output current sense circuit.

I hope the new product line up will be less depending on specialized components so your business is more resilient to shortage of products from certain suppliers

Yes, agree, but it’s very, very hard to avoid these days. LDOs, sure. But processors, DCDC converters, ADC/DAC, and even opamps (for certain performance needs) are all single sourced. A big liability in tight times, for sure.


Just stopping by to see how the parts situation with the QA403 and QA404 is coming along! Definitely a challenging time for electronics builds and parts acquisition. T.I. is doing well on the stock market (TXN), hopefully they will add some fab capacity. Looking forward to the QA403 when the time comes!

Hi, Matt.

FWIW, I would be very happy with a distortion analyzer that had inputs for an external analog supply. SMPS supplies are convenient and necessary if you are trying to run off of a single supply, but they sure do muck up the measurement environment. My 401A adds a -90dBV series of 60 Hz harmonics and then insults me with about the same level of hash above 50k Hz when I plug the laptop into its power supply. I’m going to wear out that plug.

I’m not blaming the 401 for this issue, as it obviously comes from the laptop charging circuits, and I look forward to a chance to upgrade to a successor product. It’s just that SMPS supplies create a lot of noise over a fairly broad spectrum. There are several in my lab powering different instruments. Trying to kill off the noise is a very frustrating case of Wacamole. Even the LCD display screens radiate noise. Almost makes me long for the old days of analog meters and CRT scopes. At least then you couldn’t see all the noise. :slightly_smiling_face: