Henry Engineering Matchbox HD RCA/XLR Converter

[pseudoid]

@amirm, Thank you for the review... and the enlightenment.
Holiday season makes people more kind and giving; your grading of this 'transformer-less' SE-to-Bal audio device must be an example.
So, the best solution to the channel imbalance would have to be to purchase two and only use Ch.1 of each for channels' balance.

 

[restorer-john]

Go tell Neumann, Genelec and the rest of the crowd.

The only reason they don't hardwire is saving money. They can throw whatever IEC three pin plug-lead in the box for the country and ship it out the door.

 

[amirm]

As requested, I added reverse conversion of XLR to RCA in the review.

 

[amirm]

@amirm, has this been boxed up and shipped back yet? If not, can you get permission to pop the top and take a few quick inside pix?

You are lucky it is the weekend so no, it is still here. Picture added to review with some text:

 

[restorer-john]

Whilst I love IC sockets from a repair perspective, they attract that subset of our species we all love to hate: The Opamp Rollers.

 

[pseudoid]

Whilst I love IC sockets from a repair perspective, they attract that subset of our species we all love to hate: The Opamp Rollers.

Even FOSI suggests OpAmp rolling with this statement for their ZA3 (@$100):

"The ZA3 also supports rolling op-amps.
You can replace the stock NE5532 op-amps with your preferred ones, such as the popular Sparkos SS3602 dual discrete op-amps [@$85].
We believe this customization will enhance your enjoyment even further."

But, like that lipstick on the pig, it will only double the price of the amp with minimal/incremental audio improvements.

...Picture added to review with some text:

There are some PTH which seem to be lacking full (wave) solder-coverage from the top of your view: I wonder what the bottom side of the PCB tells. Could it be one of the capacitors (poor solder joint) that's causing the imbalance?

 

[poopy]

The only reason they don't hardwire is saving money. They can throw whatever IEC three pin plug-lead in the box for the country and ship it out the door.

Not only. They also thought about a very common problem: wall socket away from your gear. At least with an iec c13 connector, you can choose the length you want. I don’t even speak about people who use power conditioners that require iec c14 connectors…. Hardwire, clearly unwanted.

 

[sam_adams]

You are lucky it is the weekend so no, it is still here. Picture added to review with some text:

Excellent!

So they have the same basic, minimalist power supply design from their DAC product. Which probably explains the noise issue.:

It won't win any awards from a design perspective. The components are all bottom shelf. No bypassing on the regulators—probably LM78/79L15. The LF353 has no bypassing—sad. Pennys scrimped . . .

The hardwired AC cord is probably there because these are professional products. They are meant to be rack mounted. Nobody has time to be fooling around behind a rack pushing in power cords.

 

[restorer-john]

Not only. They also thought about a very common problem: wall socket away from your gear. At least with an iec c13 connector, you can choose the length you want. I don’t even speak about people who use power conditioners that require iec c14 connectors…. Hardwire, clearly unwanted.

Nobody denies they are convenient. I like them for that purpose. All (well, most) of my test gear has IECs fitted.

But on large power amplifiers? No way. Especially in the US where the currents are double. C13 is 10A max, but in the US you can push 15A through it. Safe? No way. Plenty of bad, arcing IECs on PCs and HiFi gear over the years and in many cases, hot pins (=resistance). Lost count of the number of melted chassis IECs I've replaced due to arcing/hot pin issues.

Of particular concern is the huge number of IEC cables where the internal gauge is inadequate for the printed current rating of the cable (thanks to the Chinese cutting costs). They also do not stay put in their sockets when horizontal, letalone with the weight of the cable sitting for years. An attempt was made to market locking IECs - not sure where that went, but hopefully the entire safety side will be revisited soon. They are seriously not fit for purpose IMO.

Basically, a 1970 electric kettle plug that was designed to be pulled out if tugged became the defacto connector for everything. Not clever.

 

[Lambda]

You are lucky it is the weekend so no, it is still here. Picture added to review with some text:

Wow this looks like a kids hobby project from 10-15 Years ago.
Hilariously bad Layout and component choice i’m surprised it performs as good as it dose

 

[pseudoid]

Wow this looks like a kids hobby project from 10-15 Years ago.

What exactly is the problem with discrete component lay-out of the PCB?
Excluding the need for board-level ACpower rectification and all that jazz... which could have been easily accomplished externally, and w/o the low-level 60Hz Mains hump and harmonics.

 

[poopy]

But on large power amplifiers? No way. Especially in the US where the currents are double. C13 is 10A max, but in the US you can push 15A through it. Safe? No way. Plenty of bad, arcing IECs on PCs and HiFi gear over the years and in many cases, hot pins (=resistance). Lost count of the number of melted chassis IECs I've replaced due to arcing/hot pin issues.

Anything reted more than 10A requires iec C20 in Europe - Not much a concern.

Of particular concern is the huge number of IEC cables where the internal gauge is inadequate for the printed current rating of the cable (thanks to the Chinese cutting costs). They also do not stay put in their sockets when horizontal, letalone with the weight of the cable sitting for years. An attempt was made to market locking IECs - not sure where that went, but hopefully the entire safety side will be revisited soon. They are seriously not fit for purpose IMO.

I do agree though that the cables do not stay put in their sockets. This for me is a real drawback.
For that reason, I use dual locking iecs power cords: https://zonit.com/z-lock/
Did improve significantly, but could do with even more grip on the iec c13 side (female)

 

[poopy]

Nobody has time to be fooling around behind a rack pushing in power cords.

So you wear nappies because no time for the loo? What a joke…

 

[Lambda]

What exactly is the problem with discrete component lay-out of the PCB?

Thats not by itself a problem.
But the Layout Is in general unnecessarily wide spread out.
is not optimizing Loop sitze.
uses unnecessary big component's.
No ground fill, randomly chosen trace with. no polygons

 

[3125b]

The indicator LED position and tracing is a bit hilarious.
The board is the size that fits the case, it‘s dated 2003, they just didn‘t have the amount of options one would today.
Revising that PCB might be a good idea though if they sell this in serious numbers.

 

[pLudio]

They also do not stay put in their sockets when horizontal, letalone with the weight of the cable sitting for years. An attempt was made to market locking IECs - not sure where that went, but hopefully the entire safety side will be revisited soon. They are seriously not fit for purpose IMO.

I bought some https://www.ieclock.com/ C13 cables. I've noticed that Eaton has switched to C14 sockets with partly thicker prongs that the C13 connector grabs better but standard cables don't fit on the other hand.

V-Lock seems to be the standardized IEC locking system.

 

[restorer-john]

For that reason, I use dual locking iecs power cords: https://zonit.com/z-lock/
Did improve significantly, but could do with even more grip on the iec c13 side (female)

They look really good. A great option.

I'm trying to remember the locking IECs from several years back. Even some that had a foldover/spring latch around the cable like a mousetrap arm IIRC. There are also the 'deep' chassis mount males used on some PC gear (NAS/Servers etc)- they are excellent, although you really need to have strong fingers to pull them out.

 

[Mnyb]

Whilst I love IC sockets from a repair perspective, they attract that subset of our species we all love to hate: The Opamp Rollers.

"The Opamp Rollers" my new band name for a surf rock retro & nerd crossover

 

[HarmonicTHD]

Thats not by itself a problem.
But the Layout Is in general unnecessarily wide spread out.
is not optimizing Loop sitze.
uses unnecessary big component's.
No ground fill, randomly chosen trace with. no polygons

... more susceptible to noise (usually worse SINAD) - just to add to your list.

Only advantage: easier to repair and to DIY (but if you practice a bit, SMD (de)soldering is not that difficult).

(one of those audiophool myths that discrete is better in particular with uber expensive snake oil components)

 

[frabor]

I was thinking the same when I looked to the power supply, about the most basic implantation of a 78xx, 79xx ( I assume) with minimal filtering and protection. It is amazing that they are getting sinad within -100dB. Layout, oh well, funny part is that in order to go commercial you need a case as much as the board inside. The kit is functional but with a little effort (SMD, better layout, quieter regulator, better filtering) and with a minimal cost increase on the BOM they could have a stellar product.

I am designing an audio power supply for line level and this is a very nice example of non optimal design choices. It is nice to see potential design pitfalls so they can be avoided.