Introduction about HS2 headphone signal switcher.

[mrmagoo]

I've received today the “PSB2-1” switch box that I've ordered a few days ago from this website http://mfspdesigns.files.wordpress.com/.
 

You can see my other (bad) pictures and comments, and future comparison tests on my other thread here: http://www.head-fi.org/t/705169/how-do-you-compare-2-headphone-amps/30#post_10306002
Of course, you're welcome to make comments too...

 

 

[jjmai]

How does that thing work? 4 IN and 4 OUT, but only one knob.  Are the inputs all tied together?
 
Quote:

  The Fiio HS2 is no longer available for reasonable prices. Online prices range from $50 to $150!
 
Here's a possible alternative...
 
Go to:
 
dx <dot> com
 

Copy and Paste into the web site search window:  LINE5 A985 3.5mm Headphone Output Switcher

 
This is very similar to FiiO HS2 and has 4 IN and 4 OUT jacks. I bought 4 for $22 each with free shipping. Buy 1 for $25 and free shipping. Buy 3 or more for $22 with discount code:  BULKRATE
 
Line5 A985 comes with four 3.5 to 3.5 mm cables.
You will need 6.3 to 3.5  mm adapters to use 6.3 mm headphone plugs.
You will need a 3.5 to 6.3 mm cable to connect to 6.3 mm TRS source.
These are available at Amazon and other vendors.
 
I make no claims about the seller's reputation and customer service. If I receive 4 as ordered, I will post about their performance.
 
Cheers,
 
BMF
 
 

 

[bluemonkeyflyer]

 

I received an email message from the seller that said the devices are on back order. I cancelled the order and requested an email notification when they are in stock.

 

[askjeebs]

 

I managed to grab one of these from eBay and thought I'd share the internals for anyone interested:
 

 

 
 
I can't hear any added noise when all my gear is connected to it. The selector knob chooses one of the rear inputs and outputs to all four front outputs at the same time. I have no idea what those little chips on the board are though - I looked inside my HS2 and there are no chips whatsoever, only the printed circuit board and the jacks/switch.
 
The FiiO:
 

 

 
 
The interior looks a lot neater than the FiiO, but that's probably because the FiiO case is much smaller. I can't say anything about the quality of jack used in the A985 though, but the soldering looks quite good. The FiiO has multiple solder joints sanded down so that the board fits in the case without shorting it. There was a ridiculous amount of flux gunk all over the FiiO board. I think those little spring things on the FiiO board are for grounding the case, but I didn't check conductivity or anything like that.
 
My main gripe with the A985 is that the knob has grooves running along its surface in the direction that the knob is turned, so it can be hard to grip while turning it. Otherwise the A985 does its job pretty well.
 
Anyone know what those enigmatic chip-thingies could be?

 

[blasjw]

I ordered an HS2 from aliexpress.com.  The first vendor I ordered it from there came back and said discontinued/out of stock.  My 2nd attempt currently shows this status:
"The supplier is processing your order"
Keeping my fingers crossed.  

 

 

[ClassicalViola]

.

 

[miceblue]

So I opened up my HS2 and there was a lot of solder flux on the PCB; it was pretty gross and sticky.









I decided to clean it up with 91% isopropyl alcohol and now it's looking really pretty and clean-looking (relatively speaking).







Those screws were a pain in the butt to take out though. I probably gave myself a blister with the screwdriver. : (

 

[Kamakahah]

That's pretty nasty. I might check mine out as well. If the solder joints on mine look like that, I'll probably reflow them as well. Hopefully add some longevity to it.

 

[miceblue]

That's pretty nasty. I might check mine out as well. If the solder joints on mine look like that, I'll probably reflow them as well. Hopefully add some longevity to it.

Yeah, my grounding solder joints don't look too healthy, so I might go back and fix them up too.

 

[dagordon]

Can someone tell me if the grounds on the HS2 are isolated? I.e., if an input is selected are the others totally isolated? Thanks!

 

[zilch0md]

Just looking at the photos above, we can see only two traces leaving each of the three-conductor TRS jacks at the rear. There has to be a common ground - the case itself, via the springs, but I'm too lazy at the moment to get mine out and test it with a multimeter.

 

[FlyingKiwi]

Two thoughts about this interesting product.
 
1.  Noting the great deal of interest and the presence of competing products also available, is it possible for Fiio to consider doing another production run, but perhaps selling at $40 instead of $20 so they get some financial incentive for doing so?
 
2.  When doing A/B comparisons of headphones, it is essential to balance the sound level in the two sets of headphones.  There are reasonably simple workarounds for balancing outputs when comparing two different players, but it is non-trivial to balance the sound into (out of) two sets of headphones.
 
Does anyone know of a comparator type device with trim pots on it so as to be able to balance the sound outputs?
 
I'm hesitant to simply put some sort of variable resistor pad for fear of introducing new variables.  Obviously, with the inductance varying over frequency, the impacts of additional resistances in the circuit would vary with frequency too, making for a non-linear attenuation.
 
How can one achieve this balancing of headsets without adding additional variables?
 
Tks

 

[FlyingKiwi]

I ended up getting one of these units for only $25 on Amazon.  It solves the headphone balancing challenge, and for only $5 more than the no-longer-available Fiio unit, seems like the best game in town now
 
 
http://www.amazon.com/gp/product/B000KIPT30/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B000KIPT30&linkCode=as2&tag=drti-20&linkId=XQ6HCVFMRVSB4NRE 
 

 

[miceblue]

I ended up getting one of these units for only $25 on Amazon.  It solves the headphone balancing challenge, and for only $5 more than the no-longer-available Fiio unit, seems like the best game in town now


http://www.amazon.com/gp/product/B000KIPT30/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B000KIPT30&linkCode=as2&tag=drti-20&linkId=XQ6HCVFMRVSB4NRE 

The user manual for it says it has an 80-ohm output impedance. I'm pretty sure that's not a good thing to have if you want to make accurate headphone comparisons between lower-impedance headphones.

 

[FlyingKiwi]

I had a look inside the unit.  It is, unsurprisingly, a very simple circuit, with each channel having its own potentiometer (as we can see) and IC to modify the sound level.
 
I didn't see anything that would immediately/obviously indicate a high output impedance, so wouldn't mind guessing that something got lost in the translation between German (or maybe originally Chinese!) and English.  I've been pleased with it as a test rig.