A-B headphone amp gizmo

[Deleted]

I've finished the A-B test switching gizmo.



If anybody is interested in testing their amps and their different sound signatures in (blind) A-B tests side by side then this might be interesting for you.

If you do not care about this kind of experiments stop reading this and surf to another more interesting thread....

I will send it to you, or if more are interested to the first pesron on the list, so you can play around with it F.O.C.
Keep it as long as you want (not indefinitely) and then send it back to me or the next person who wants to play with it.

It is specifically made/designed for testing headphone amps.

You will need:

1: At least 2 amps, at least one with a volume control and 6.3mm jack out (or 3.5 with a converter, not included).
2: a source with RCA out.
The amps need to have RCA in or you need to have converters so it takes RCA.
a source with a volume control on it (PC audio or DAP with volume control or CD/DVD player with volume control.
If you don't have a source with a volume control you can always use a pre-amp between it.
3: One (or more) pair(s) of headphone(s).
4: revealing music.
5: a good set of ears.
6: time to play with it.

The gizmo has 2 quality headphone wires with goldplated 6.3 mm stereo jack plugs to fit in 2 amps and a gold plated 6.3mm stereo Jack socket for the headphone.

There is the obvious AB switch.

It will come with instructions.

a set of high quality RCA splitter cable wit goldplated RCA's is included which will split the source signal to the 2 amplifiers.

the 'A' section has 3 resistor switches so you can match the impedances of the amps (if known) or play around with it to find your optimal setting.
It can add: 15 - 30 - 45 - 60 - 75 - 90 or 105 Ohm to the already present output resistance of the Amp in the 'A' line.

Anybody interested in some fun experiments ?

Just PM me or post in this thread.

[clausdk]

I would love to borrow it for the next danish meet, could be fun A/Bing some serious costing amps to cheap ones,

We did a test at the meet last month and not a single one could point out the FLAC version when compared to 128, 256, 320 compressed files, it was from a Sansa clip and we all blamed the player

Later we found out that something was messed up in the numbers

So I think 2 or 3 got it right afterall..

[Deleted]

Nov 12, 2010 20:03:19 GMT @solderdude said:

I've finished the A-B test switching gizmo.



If anybody is interested in testing their amps and their different sound signatures in (blind) A-B tests side by side then this might be interesting for you.

If you do not care about this kind of experiments stop reading this and surf to another more interesting thread....

I will send it to you, or if more are interested to the first pesron on the list, so you can play around with it F.O.C.
Keep it as long as you want (not indefinitely) and then send it back to me or the next person who wants to play with it.

It is specifically made/designed for testing headphone amps.

You will need:

1: At least 2 amps, at least one with a volume control and 6.3mm jack out (or 3.5 with a converter, not included).
2: a source with RCA out.
The amps need to have RCA in or you need to have converters so it takes RCA.
a source with a volume control on it (PC audio or DAP with volume control or CD/DVD player with volume control.
If you don't have a source with a volume control you can always use a pre-amp between it.
3: One (or more) pair(s) of headphone(s).
4: revealing music.
5: a good set of ears.
6: time to play with it.

The gizmo has 2 quality headphone wires with goldplated 6.3 mm stereo jack plugs to fit in 2 amps and a gold plated 6.3mm stereo Jack socket for the headphone.

There is the obvious AB switch.

It will come with instructions.

a set of high quality RCA splitter cable wit goldplated RCA's is included which will split the source signal to the 2 amplifiers.

the 'A' section has 3 resistor switches so you can match the impedances of the amps (if known) or play around with it to find your optimal setting.
It can add: 15 - 30 - 45 - 60 - 75 - 90 or 105 Ohm to the already present output resistance of the Amp in the 'A' line.

Anybody interested in some fun experiments ?

Just PM me or post in this thread.

YES PLEASE FRANS.

[Spirit]

Nov 12, 2010 20:58:19 GMT @clausdk said:

We did a test at the meet last month and not a single one could point out the FLAC version when compared to 128, 256, 320 compressed files,
<snip>
So I think 2 or 3 got it right afterall..

I should hope 2 or 3 got it right....
Using my X-Meridian (soundcard) as a source, I could easily pick 128 from 256 in a blind AB test. Treble quality goes out the window.

[Deleted]

Nov 12, 2010 22:21:29 GMT Spirit said:

Nov 12, 2010 20:58:19 GMT @clausdk said:

We did a test at the meet last month and not a single one could point out the FLAC version when compared to 128, 256, 320 compressed files,
<snip>
So I think 2 or 3 got it right afterall..

I should hope 2 or 3 got it right....
Using my X-Meridian (soundcard) as a source, I could easily pick 128 from 256 in a blind AB test. Treble quality goes out the window.

Treble quality even goes out the window with 320, Dolby Digital stereo,DTS stereo (to a lesser extent), and ..FLAC unless properly converted to .flac at a record company such as Linn Records, and then, only if reconverted to .wav on a far better than average commputer . Playing .flac files on "the fly"where they first need to be converted to .wav (or equivalent) during playback also results in "veiled " treble.
Alex

[Deleted]

This thing is not for comparing FLAC etc but for testing headphone amplifiers.

I believe the comments on FLAC belong in the FLAC difference thread ?

If you can start 2 similar players with the same song at the same time with similar amps then it could be used for this too.
But WHAT will you be listening to ? different amps? different players? different files?

The thing will be shipped to Mick.
If more are interested in fooling around with this gizmo let me know (or Mick once he received it) and he can pass it on.
It'll only cost you some time and shipping costs to the next person or me.

By the time Claus's next meet is coming it will be shipped to Claus.

[Deleted]

We did a test at the meet last month and not a single one could point out the FLAC version when compared to 128, 256, 320 compressed files,

I feel the reference to .flac is quite appropiate here , as Claus mentioned it in the comparisons with compressed files.

[clausdk]

Nov 13, 2010 7:13:27 GMT @solderdude said:

This thing is not for comparing FLAC etc but for testing headphone amplifiers.

I believe the comments on FLAC belong in the FLAC difference thread ?

If you can start 2 similar players with the same song at the same time with similar amps then it could be used for this too.
But WHAT will you be listening to ? different amps? different players? different files?

The thing will be shipped to Mick.
If more are interested in fooling around with this gizmo let me know (or Mick once he received it) and he can pass it on.
It'll only cost you some time and shipping costs to the next person or me.

By the time Claus's next meet is coming it will be shipped to Claus.

I know this belongs somewhere else, but just wanted to keep up the off topic thing we have going on this site ;D ;D

[Deleted]

Frans,

I wonder whether it's worth making an external box that offers variable resistance to put in line at the output of all amps?

This sounds a bit finnicky, but I have now tuned in to the Panda big time and there is actually a slight difference with a 38 ohm adapter in line with mine. (Making the output impedance 120 ohms)

At first, I couldn't really hear much but it is there and is not as simple as just the treble region coming down or bass louder. It's a 'balance' type thing that is hard to describe without looking at the frequency response differences. It's very subtle.

That's all well and good with the K701, but then another headphone may require a totally different resistance and having a switcher in line could do that.

However, maybe there are negatives to having yet another thing in the signal path?

Have you tried anything like this with a high quality switcher in line?

[Deleted]

The switches are high quality.
they have a rather high contact pressure and good contact surfaces.

One could use the test box as a simple means to vary the impedance by flipping switches and one can easily find 'sweet spots' for certain headphones.
Mick is the first one to use it.
If you want Mick can send it to you when he is finished with it.
Should you like the opportunity to play with impedances then you could make (or have made) a very HQ impedance selector box.

The biggest changes in sound happen when doubling the impedance.
In between the difference is smaller.
10-22-47-100 will be enough.
anything in between will not have a dramatic effect.
The amp it is used with MUST have a low impedance of 10 Ohm or lower.

For this AB box it was better to approximate as much as possible values.
As you have already noticed the output impedances DO have influence on the sound.
For some cans more then others.
To really listen to the amps and not to output impedances it is important to have the possibility to match the amps.
Otherwise it is unfair.
Ofcoarse you can also compare amps as they are (leaving all switches to '0'.

[Deleted]

As you have already noticed the output impedances DO have influence on the sound.For some cans more then others.To really listen to the amps and not to output impedances it is important to have the possibility to match the amps.Otherwise it is unfair.

Yes, the output impedances do affect the sound of the headphone and I don't think it's just a simple relationship. (ie there's more bass, or there's more/less treble) It's a subtle 'balance' of tones thing.

I noticed this when I had the Meier audio crossfeed in line. (Before it was pinched) That had selectable output impedances and it really helped the HD650 a great deal. I used that a lot.

The Beyer DT770 pro also seems happier at 120 ohms. It kind of evens out and the mids are better. The AKG becomes very slightly less sibilant but there's also something going on (I think) slightly lower in the treble. I'm able to pay them REALLY loud now without pain!! The bass has more prominence but I don't think it's louder - it just seems louder in comparison with the rest of the frequency. It's quite hard to explain - it just feels more 'right'.

With a variable switch in line, even if you didn't want to hear a 120 ohm type response from your headphone, you could tip it up or down to suit what you're listening to. It's subtle, as I said, but it can enhance the music by also being incorrect as well!! At least a switch gives the option and makes your headphone slightly more of an all rounder.

A kind of tone control done through impedance matching.

[Deleted]

It's not meant as a (subtle) tone control.
Most headphones are designed to perform at their best on a standardised 120 Ohm output.
Not all of them though.
Also some may prefer a slightly different sound and some cans benefit from lower impedances.
My DT990 sounds much better (flatter) with low Ohmic outputs.
This is also true when measured or argued.

When I have some time I will make an explanatory about output impedances and why they have a certain effect. (a pdf probably as it will include graphs)

[Deleted]

Beyers and Senns are set up for 120 ohms, it may be useful to know which manufacturers decided to standardise.

AKG is another, but not sure about AT.

To me, it seems like a subtle tone difference i that the balance between the frequencies slightly alter. I can't detect any better resolution. It is quite subtle though and you need to be very familiar with your amp and headphone before trying this. Maybe the A/B device will help to focus on those exact differences.

I can't exactly place where whatever happens to the AKG with extra load is. It's more obvious somewhere in the treble, but I don't think it's the top end it's the bottom end of the treble. - maybe the part that can make headphones sound 'clattery'. I had that problem with the AT 1000 - they clattered around in the lower treble region. A device like this may have helped enormously.

[Deleted]

All will be clarified soon.

I am writing an article on this subject so everyone can understand what, how and why the output resistance makes a difference.
a lenghty article that must be easy to read...

[Deleted]

a lenghty article that must be easy to read...

I can't help it if I'm thick!! I was born this way.

[oohms]

Something like this would make it a truly blind test

www.jaycar.com.au/productView.asp?ID=SP0764&CATID=28&form=CAT&SUBCATID=652

[Deleted]

The impedance thing explanation is here:

www.mediafire.com/file/ms4k8wuqt18x8s3/resistance%20and%20impedance...%20an%20explanation.pdf

and I created another thread for it in the amplifier section where it can be dsicussed and commented (to keep this clean)

[Deleted]

Something like this would make it a truly blind test

I use this for mine:

[Deleted]

It's just hard to breathe in one of those.
or at least I get the impression it is ..

[Deleted]

Nov 14, 2010 19:17:00 GMT @solderdude said:

It's just hard to breathe in one of those.
or at least I get the impression it is ..

Yes, but your last moments are oh .... so musical!!

[PinkFloyd]

CEO of Sennheiser on his way to conduct a blind listening test:

[Deleted]

Nov 14, 2010 20:20:36 GMT PinkFloyd said:

CEO of Sennheiser on his way to conduct a blind listening test:

;D ;D ;D

[PinkFloyd]

Nov 14, 2010 20:34:17 GMT @iancraig10 said:

Nov 14, 2010 20:20:36 GMT PinkFloyd said:

CEO of Sennheiser on his way to conduct a blind listening test:

;D ;D ;D

They take their blind testing very seriously in Germany Ian Don't even "think" about turning up "old school" with a white stick.... it's state of the art testing these days and a well groomed "pedigree" dog is the minimal entry requirement

[Deleted]

I know I shouldn't laugh..... but I just can't help it. I'm so politically incorrect. ;D ;D ;D

[Deleted]

Nov 14, 2010 20:20:36 GMT PinkFloyd said:

CEO of Sennheiser on his way to conduct a blind listening test:

Oh that's sooooo last year sweetie.

This Autumn we simply must have a true German breed.

Walking is also not "now" lovey, a nice Harley is de riguer for your successful city man.

Fashionable "shared senses canines" must also have driving licences.