Neurochrome HP-LOAD Review (Headphone Dummy Load)

[tomchr]

Here are 589 IEMs measured by ReferenceAudioAnalyzer:

Is there any way to get access to the raw data. I see the tables on RAA, but don't see a download option. I guess there are other lists as well, but this one seems pretty darn comprehensive.

Tom

 

[JohnYang1997]

Okay a little perspective.

Looking back through the HPA reviews here at ASR I do see sequence automation steps for HPA input voltage and output power measurements, The AP APx500 software and APx555 hardware “sequence mode” increments through each step of the test sequence except the switching of the test loads.

I also see two typical test loads; 300 Ohms and 32 Ohms. I do not see any complex impendence loads in the ASR reviews. I do not see any evidence of automated switching between the test loads.

So what we do have is a $1500 solution looking for a problem to solve.

How is that for relevance?

Thanks

Did you read the review?

Anytime you see a graph like this:

It is produced using HP-LOAD box.

More measurements done on these:

 

[tomchr]

can you make a reactive speaker load box, able to handle up to 1kW (or more) up to 8-Channels of amplification? This would handle stereo and all MCH amp types out there.

I have no doubt it will be a bit more expensive

"A bit more". 8 x 1 kW (or more). That'll be vastly more than "a bit more". If that's your requirement, I think you should throw some money at the Swedes and buy their Power Cube.

8 kW is a lot of heat to have to get rid of. Then you add the electrical challenges and the challenges of switching those types of power levels.

Tom

 

[tomchr]

There is a baggie with several R values of 12 watt precision Wire-wound Mills Vishay resistors in the bin near my bench that does just fine testing HPA's.

If that works for you, that's great. More power to you! I went down that road to start with as well. As did Amir (as you can read in Post #1). Both of us found that solution frustrating and wanted something better. So I made a load box, added it to my website, and put a price tag on it. I don't understand why that's so outrageous. Businesses do this all the time.

Don't like the product? Find it too expensive? Don't buy it! It's pretty simple when you think about it. Yes. I said the T-word there. My bad.

Tom

 

[tomchr]

Here is mine [...] No cables to reduce residual rig impedance i.e. you can measure 50mOhm output and see .05ohm.

Mine does that too thanks to the use of Kelvin sensing of the voltage right at the headphone jack.

$20 retail ))

Great! Take it to market. Compete with me.

Those 0805 resistors can handle 125 mW, by the way. The 1206 size might get you to 250 mW. Many are clamouring for 5 W at 50 Ω.

Tom

 

[wwenze]

There is one use case for this kind of things: The industrial / scientific / commercial.

While for a random guy making a random measurement of a random headphone then the random performance of the random load probably does not matter.

However if you're an R&D who is trying to optimize your equipment, you cannot have a load that varies in behavior. That includes noise. We all hate doing experiments and seeing results only to find out oh it's because something else happened like the temperature changed.

You want repeatability, be it your own experiments or when others are doing the same experiment following your instructions. Maybe he uses a different load and sees a different result. Maybe something fails at 32.0 ohms but not at 32.7 ohms (contact resistance). Maybe you're trying to characterize your parts to sell - You want to sell them as 0.1% precision, but your measuring equipment is 1% precision. How do you prove it? (Possible with some statistical tricks, but not nice.)

Yes, for somebody like me who makes negative money measuring audio stuff, the $20 board might be a godsend as opposed to DIYing. However for multiple engineers each paid $150 per day in a lab, the cost of building a good one and the time saved from convenience and incorrect conclusions becomes high.

 

[Doodski]

However for multiple engineers each paid $150 per day in a lab

Some engineers make multiple hundreds of thousands per year or more. I met a petroleum chemical engineer and he said he won't get out of bed for less than ~$250,000.00 a year and he said he knows a couple of guys like him make over $450,000.00 a year. $150.00 a day is not even close to what a pipefitter or heavy duty mechanic make.

 

[wwenze]

Some engineers make multiple hundreds of thousands per year or more. I met a petroleum chemical engineer and he said he won't get out of bed for less than ~$250,000.00 a year and he said he knows a couple of guys like him make over $450,000.00 a year. $150.00 a day is not even close to what a pipefitter or heavy duty mechanic make.

Yea but I'm from Asia. We would pay $50 a day for a mechanic.

 

[IVX]

Great! Take it to market. Compete with me.
Tom

Oh no, I'm not such a technical expert to go seriously with so ambitious project like a dummy load. I'll probably gift my load PCBA to Cosmos ADC users as a free rig for my DACs(<600mW) calibration. Let's see..

 

[IVX]

Yea but I'm from Asia. We would pay $50 a day for a mechanic.

I think US mechanics vs mainland Chinese is hard to compare. The same thing with EE, a different level of understanding the profession. Education..

 

[staticV3]

Is there any way to get access to the raw data. I see the tables on RAA, but don't see a download option. I guess there are other lists as well, but this one seems pretty darn comprehensive.

Tom

I don't think there is. I just copy pasted the data from this page:
https://reference-audio-analyzer.pro/en/param1.php#gsc.tab=0
I then cleaned it up a bit to remove duplicates and active Bluetooth headsets, since those will show their ADC Zin instead of the driver impedance.

 

[DualTriode]

If that works for you, that's great. More power to you! I went down that road to start with as well. As did Amir (as you can read in Post #1). Both of us found that solution frustrating and wanted something better. So I made a load box, added it to my website, and put a price tag on it. I don't understand why that's so outrageous. Businesses do this all the time.

Don't like the product? Find it too expensive? Don't buy it! It's pretty simple when you think about it. Yes. I said the T-word there. My bad.

Tom

Hello Tom,

It is not the expense that concerns me.

You have made no attempt to sell your product.

You have not told us how the “automation” functions. Come to think of it @amirm did not how tell us in the review how the automation functions either.

This is a lot like trying to sort a conversation with my wife when she starts a story with the word “they”.

Tell us about this “automation”. Does the software start at the top of an APx500 programed sequence and automatically loop back through with each different load. Is it VB Express, LabVIEW or is it MATLAB controlled. How is it programed?

Short version:

If you want to sell your product you need to tell us what your product does, how it can save me time and money and how I can apply it in my lab.

Thanks DT

 

[jtwrace]

Short version:

If you want to sell your product you need to tell us what your product does, how it can save me time and money and how I can apply it in my lab.

Thanks DT

What lab do you have? Do you own an AP? Manufacturer? Extreme Hobby? Please elaborate.

 

[DualTriode]

What lab do you have? Do you own an AP? Manufacturer? Extreme Hobby? Please elaborate.

I play in Sparky’s Lab. Sparky is my cat. There is no intention to make a profit

I have a pretty complete set National Instruments PXI instruments centered around noise and vibration.

For the audio measurement sort of stuff we do here at ASR. I have an APx555, APx1701 (speaker measurement amplifier tool), GRAS 45CA headphone measurement fixture plus an assortment of GRAS measurement microphones.

Thanks DT

 

[tomchr]

Cat picture, please! Love cats.

Copied directly from the HP-LOAD product page. Emphasis added.

The HP-LOAD features:

• Caddock MP900-series power resistors with ±1 % tolerance
• Wima MKP2 polypropylene capacitors
• Sensing of the DUT output voltage by a differential Kelvin connection
• Balanced output for easy interfacing to audio analyzers
• Audio Precision APx-500 compatible 5 V remote control input
• Minimum power handling: 8 W per channel
• Maximum operating voltage: 63 V RMS (100 V DC)

[...]
The load impedance can be selected manually or by applying a 5 V logic signal to the control port on the rear panel of the instrument. The control port is compatible with the Audio Precision APx500 audio analyzers. The remote control allows you to perform fully automated testing across a wide range of load impedances.

You can find the HP-LOAD User's Guide in the Resources tab on the product page. Here's the link: HP-LOAD_R1p0_UsersGuide.pdf
The timing diagram for the control interface is shown on the last page of the PDF. I have also provided an AP project script that cycles through all the impedances to get you started. You can find that on the resources page as well.

Basically you toggle a bit on the control port to select REMOTE mode. Then present a bit pattern corresponding to the load impedance you'd like. That's all there is to it. I use it with the APx500 software's Sequence Mode. I'm sure you could use it through the APx500 API as well.

I assumed that those who have an APx500-series audio analyzer would be aware that it has an Auxiliary Control Output (DE9 connector) on its rear panel. You can find a brief description of it on page 14 of the APx500 User Manual and a more detailed description of it on pages 729-730. The page numbers refer to the latest revision of the manual as of today available for download on AP's website.

I'm not sure how much more information I can provide. To me it's pretty self-explanatory, but if I'm not providing enough information on how the HP-LOAD is intended to be used I'm open to constructive criticism. Just don't expect me to communicate by interpretive dance or something.

Tom

 

[DualTriode]

Did you read the review?



More measurements done on these:
View attachment 144738View attachment 144739View attachment 144740View attachment 144741View attachment 144742

Yes I read the review.

@amirm tells us that the load switching is not automatic yet.

Thanks DT

"Audio Precision has an AUX bus that you can control through automation. This port is compatible with that so you automate testing of the amplifier across the full set of loads with just one click of the mouse! I am not yet using this but should do to save some work. "

 

[tomchr]

@amirm tells us that the load switching is not automatic yet.

No. He's telling us that he did not use the automation feature for the reviews mentioned in Post #1 but that using that feature would save time. That is not the same as saying that the HP-LOAD does not support automation, which is what you seem to believe. Do you see the difference?

The HP-LOAD does support automation. As I mentioned in Post #30 I used the automation in my production testing of the TCA HPA-10 headphone amps. It cut the test time roughly in half as the script didn't have to wait for me to swap clip leads around.

Whether Amir chooses to use the automation feature is his choice. Nothing prevents him from selecting the impedances one by one using the front-panel switches and reporting the measurements. The automation feature just makes this process easier and more repeatable as it eliminates a source of (user) error.

On my website, I describe that the HP-LOAD features a control port that allows you to control it with an APx500-series analyzer (or anything else capable of generating 5 V logic signals). I describe how to use the feature in the User's Guide. I provide an APx500 Sequence Mode project file that cycles through all the impedances one by one, which you can use as a starting point for your own scripts. Seriously?! What more do you want? Please be specific.

Tom

 

[scott wurcer]

Here is mine Please note, 32 steps from 10 to 300ohm L/R independent and balanced/unbalanced 3.5/2.5mm supported. No cables to reduce residual rig impedance i.e. you can measure 50mOhm output and see .05ohm. Also possible to off all resistive load to use real headphones instead. $20 retail ))
View attachment 144615View attachment 144616

Folks here need to remember that this is not much of a DIY site,

 

[tomchr]

Thanks Scott.

Tom

 

[DualTriode]

Hello Tom,

I am sure that the HP Load does everything that you say that it does.

On the other hand if I had one on my bench it would take me a long time around before I sorted the cords and programing to make the TTL load switching work. I don’t think that that I am much different than most bench builders. There is always one more thing to do before I sort the automatic testing sequence.

Scott, come on now!

We all know that you have a soldering station on your bench and 6 bins of parts in your garage just like 90% of the folks here at ASR. That is the stuff of DIY.



Thanks DT