[Ferbose]

Despite several users chiming in on this thread, nobody has yet made a head-to-head comparison between two ways of connecting headphone from DAC1's XLR:
method 1: Use an ordinary XLR->RCA adapter (Pin2->Signal, Pin1&3->Ground)
method 2: Float Pin 3 (Pin2->Signal, Pin1->Ground)

My previous post is based on method 1. But DAC1's engineer and manual suggest method 2. In order to see if there is a real difference, I decided to conduct the experiment myself.

I bought altogether four Hosa XLR->RCA adapters from sweetwater.com
http://www.sweetwater.com/store/detail/GXF132/
The adapters are wired as method 1.
Some of these adapters can be loosened by hand, so you can directly look at the soldering inside. Others are hard to open and may require clamps.
Anyway, I opened two of them and used a swiss army officer's knife to saw off the solder between pin 1 and 3 (foutunately the wire is soldered to pin 1 and pin1->pin3 is connected by a thread of solder). The solder material turns out to be harder than I thought, so it took about 10 min to cut through it.
After this modification, I have two adapters connected in method 1 and two in method 2, and a direct comparison can be made.

In a nutshell, I can clearly hear differences between the two connection methods. Not surprsingly, method 2 sounds better. DAC1 manual says not floating pin3 causes " very high levels of distortion," and that is an EXAGGERATION. I did not detect any difference in tonal quality in any frequency range, so basically the both methods sound very similar. However, method 2 has an slight edge in terms of details and resolution. The differences are quite small in absolute terms, but in terms of creating an audio illusion, the improvements are significant. With method 1, the XLR is already a noticeably better headphone amp than the headphone jack. With method 2, another level of refinement is added. If method 2 scores 10 in terms of sound quality, I would say method 1 scores 9 and headphone jack is 7.

In the next follow-up post, I will describe some of the very intriguing sonic results I am able to hear with method 2. Details of associated quipment and comparison method will also be described.

 

[OracleGuy]

Can this same mod. be used to connect HD650s to *any* DAC with balanced XLR outputs?

In particular, the upcoming DAC from PS Audio will also have balance XLR outputs.

 

[Ferbose]

Quote:

Originally Posted by OracleGuy Can this same mod. be used to connect HD650s to *any* DAC with balanced XLR outputs? In particular, the upcoming DAC from PS Audio will also have balance XLR outputs.

If you use this adapter:
http://www.sweetwater.com/store/detail/YMR197/
You can use anyheadphone with a 3.5 mm stereo plug from XLR with the method described in post #61.
For HD580/6xx, you can aldo modify the cable so it will be driven in four conductor mode (balanced headphone connnection), as each channel has its own ground wire.

 

[OracleGuy]

Quote:

Originally Posted by Ferbose If you use this adapter: http://www.sweetwater.com/store/detail/YMR197/ You can use anyheadphone with a 3.5 mm stereo plug from XLR with the method described in post #61. For HD580/6xx, you can aldo modify the cable so it will be driven in four conductor mode (balanced headphone connnection), as each channel has its own ground wire.

Thanks -- let me rephrase my question: is there anything special about the DAC-1 which makes the XLR outputs so good for driving headphones, or would any DAC with balanced outputs be as good?

 

[zool]

Quote:

Originally Posted by OracleGuy Thanks -- let me rephrase my question: is there anything special about the DAC-1 which makes the XLR outputs so good for driving headphones, or would any DAC with balanced outputs be as good?

Well, for one you can regulate the volume on the balanced XLR out's on DAC1. It also seems to have a pretty good synergy with HD650.

 

[OracleGuy]

Quote:

Originally Posted by zool Well, for one you can regulate the volume on the balanced XLR out's on DAC1. It also seems to have a pretty good synergy with HD650.

That's true -- the DAC-1 volume controls are a big plus. I guess the only other option would be to attenuate the signal digitally, e.g., if using a computer as source.

 

[Ferbose]

Quote:

Originally Posted by OracleGuy Thanks -- let me rephrase my question: is there anything special about the DAC-1 which makes the XLR outputs so good for driving headphones, or would any DAC with balanced outputs be as good?

I read that good XLR outputs are not affected by the impedance it sees and some even does not mind a 120 ohm load. DAC1's XLR probably is one of them. The preamp function of DAC1 makes its XLR very suitable for driving headphones.

 

[Iron_Dreamer]

Quote:

Originally Posted by Ferbose I read that good XLR outputs are not affected by the impedance it sees and some even does not mind a 120 ohm load. DAC1's XLR probably is one of them. The preamp function of DAC1 makes its XLR very suitable for driving headphones.

I'm currently using it to drive the 80ohm Beyers, at I even used it with the 32-ohm Grados, using an adapter cable.

 

[Ferbose]

As a follow-up to post #61, I will report the sonic differences I detected between not floating and floating pin 3 of XLR.
Connection method 1: Use an ordinary XLR->RCA adapter (Pin2->Signal, Pin1&3->Ground)
Connection method 2: Float Pin 3 (Pin2->Signal, Pin1->Ground)
First, let me state my setup during the comparison:
Transport: Sony DVP-NS900V SACD/DVD player, linked through inexpensive optical fiber.
Power: $40 Belkin surge protector, connected through DAC1's sotck powercord.
Headphone: AKG K501, with a bit of tweaking with Scotch tape

In terms of tonal quality, the two connection methods appear to be the same. The largest noticeable difference is the increased sense of space around instruments for method 2. In method 2, an instrument portray a more diffuse sound field that extends upward and define a sense of space. This can be called ambience or airiness as well. This sense of space reveals much information about how the performance is miked. In some chamber music recordings, I can clearly tell that instruments are individually miked and not mixed very well. Each instrument has its own sound space that does not intermingle and does not fit together. On the other hand, recordings using only 2 mikes portrait well-integrated soundstage for all instuments. With method 1 these subtle spatial cues are very hard to detect.

Using different instruments, I discovered that methos 2 simply gives better resolution and details. For viola, the friction between the bow and the string is more distinct. For violin, the sound is more resonant, fuller and smoother. Transients from pucking guitar strings and piano hammers are clearer. Bass is tighter and less fat. Triangles have more metallic eady sounds.

Overall, floating pin 3 does sound slightly better. The increased the sense of space takes me closer to the microphone than ever before. For expample, I have three piano recordings that all sound excellent. But the tonality of the three pianos are very different and that used to confuse me. With the added spatial resolution resulting floating pin 3, I can kind of tell one of them places the mike near the lid, another is like living distance from the piano, and the last one is miked in a large concert hall from a dsitance. I can now understand why the tonality of the piano would be quite different in each separate scenario. Amazing resolution!

 

[Hello]

OK, so I have a general question for you guys that I hope you don't mind answering. How does the benchmark XLR drive phones in comparison to the top non-balanced solid state amps that are out there? Is it accurate to say that the benchmark's XLR output is on the same level as amps such as gilmore lite + PSU upgrade, headroom max, etc? I am getting the, possibly false, impression that only balanced amps can really best it's XLR output.

(Say, using Sennheiser HD650's as the headphones...)

 

[wali]

maybe you should checkout this thread: http://www6.head-fi.org/forums/showthread.php?t=109105

 

[ayt999]

Ferbose - did you mod the Sennheiser cable to end in dual XLR plugs, or are you using the 3-conductor plug that's originally on it, but with convertors? have you tried running the drivers between the positive (pin 2) and negative (pin 3) signals?

 

[Ferbose]

Quote:

Originally Posted by ayt999 Ferbose - did you mod the Sennheiser cable to end in dual XLR plugs, or are you using the 3-conductor plug that's originally on it, but with convertors? have you tried running the drivers between the positive (pin 2) and negative (pin 3) signals?

I only have K501, so I only use 3-conductor plug.
XLR is first converted to RCA (pin 2 to hot, pin 1 to ground)
2 RCAs are then converted to one female stereo plug.
This means left XLR pin 1 and right XLR pin 1 are grounded together.
I guess gounding together left and right pin 3's (negative signals) would cause problems (channel crosstalk?).

 

[ayt999]

oh, I was under the impression you were using HD650's or similar for some reason.

K501's would be harder to test that on... and for practical purposes your two testing conditions are all that is possible / needed for your headphone.

grounding together the two negative pins and using that as a ground would probably cause trouble and I was only suggesting that if you had individual cables going from the output pins to the headphone. but if possible, this configuration is best for a headphone IMO.

if I have the time to make another convertor cable that will wire my headphones in your method 2 scheme, I might do the comparison myself. right now I have two pairs of dual mono headphones, both wired for use between pins 2 & 3 of the XLR output.

 

[bubruelz]

How would a Singlepower MPX3 or PPX3 hooked up to the RCA outs of the DAC1 compare to the XLR outs of the DAC1 going straight to the HD-650 as has been discussed here (which was a brilliant idea, by the way)?