[spendorspain]

Hi

I have a doubt about the virtues of the "balanced" connection for headphones (separate ground for each channel and not the usual tip-ring-sleeve jack). If the amplifier is only "semi-dual mono", with the power tranformer shared between both channels (all the rest is dual: there are two independent power supplies and amplifier sections for L & R) is the use of a 4-pin connector preferable? What are the expected sonic improvements?

If I use any kind of crossfeed, which by definition mixes one channel with the other, is it worthwhile to maintain both grounds separated at output connector?

What is your opinion about the use of the Neutrik SpeakOn 4-pole connectors for that use? On the paper, they are even better than the 4-pin XLR line level plugs (multifinger silver plated brass contacts, latching, completely short-proof, easy to connect/disconnect, different types of accessories and adaptors...), but it seems everybody uses XLR (one 4-pin or 2 x 3-pin) or 2 x 1/4inch plugs

Regards
Jose

 

[GregVDS]

why not. I think the minus pins are connecting before the lives, so maybe it's a supplementary advantage. No shortings between ground and channels as with a simple jack. I use it to conduct my regulated voltage between my PSU and my amp.

Cosmetically, there is always a blue detail in the connector, so not the taste of everybody.

I don't know if there is a real plus to have grounds separated. But one ground could be used for sheilding, the other for normal ground.

What kind of crossfeed do you use?

All the best,

GregVDS

 

[nikongod]

MOST balanced amps dont use sperate ground chanels.

HOWEVER!!! since the ground chanel is only used a a reference, the fact that it is chared is typpically of little concequence with regards to chanel crosstalk.

something VERY nice about the use of xlr plugs (as opposed to the "copmon consumer standard" 1/4" plugs...) is that they can be unplugged and plugged into amps that will short and explode if given the chance. a "standard 1/4" plug" gives that chance every time its plugged in. there are few other advantages of a xlr plug over other "more comon" plugs, but that has all been discussed in old threads.

edit: on re-reading the op, it seems that this is more of a q comparing the value of a 4-pin xlr to dual 3's and 1/4" plugs...
go for the 4-pin xlr! for sure. some will say 5-pin, but if you build all of your amps for 4-pin xlr's, people who have not yet upgraded the abysmal stock k-1000 cable can buy them and use them without an adapter... lots of people have k-1000's, how many have 5-pin'd headphones?

 

[Daroid]

The speakon plugs are intended for speakers, and can be seen in "action" at concerts, because it is available as a weatherproof solution, and supports a great amount of power. The connector is rather large though (and blue

)

Reason why not to use it: Standards. If you were to sell an amp you would never sell any with speakon sockets for balanced connection, because it wouldn't comply with standards. The standard is XLR (afaik).
Speakon will work, as well as if headphones came with a three-prong plug that fits in the wall sockets instead of the jack, would also work.

 

[flecom]

most companies selling balanced headphone amps use two 3 pin xlr's... which i think is the stupidest thing, especially since they are only using 2 pins per plug...

using the 4 pin XLR (ala K1000) would make the most sence imho and i use it on all my amps... plus the body is a 5th pin (aka shield, if your using a shielded cable)

 

[Garbz]

Daroid is half right. Selling the amp will certainly give a What The? to the the buyer when he sees it. But unfortunately there is no standard. AKG put 4pin XLRs on, Headroom put 2x 3pin XLRs, some put 2x TRS plugs on so standards isn't an issue.

What the connectors boil down to is practical purposes. SpekOn connectors are HUGE! I certainly wouldn't use them for a small headphone connection but each to his own. What's important is that a device can't be mistakenly plugged in and blown up, and that the connector serves it's purpose. 2x 3pin XLRs out allow you to use the headphone amp as a balanced preamp but then you need 2 cables. If you use a 4 pin xlr you loose that function but get a single connection.

What would be ideal then is a 5 pin XLR connector. Now there's a connector which has a pin for ever output. You can float the GND when using balanced headphones, you can build an adapter to 2x 3pinXLRs for using it as a balanced preamp. You can build an adapter for TSR that floats the -ve channels for standard headphones.

Finally the merrits of balanced are somewhat reduced with a crossfeed, and that's the channel separation. But remember the final amp will still have twice the voltage, twice the slew rate, each channel sees half the impedance, and the final mess puts out 4 times the power.

 

[nikongod]

i still disagree with the 5-pin.

a front panel with the following would accomidate EVERY "mass produced" aftermarket headphone.

2 "dual" 1/4" TRS&3-pin xlr plugs. wired so that all conections were used. wire in necessary resisotrs so that the amp wont short when you unplug a 1/4" plug with the amp on. this only efects the 1/4" plug with the neutrik combo jacks.
1 4-pin xlr.

3 jacks, and your done. the only thing that is left out is a headphone that is aftermarket wired with the 5-pin conector. it is easier to build 1 dongle (or reterminate) to meet one of the 3 (or 4) above accomidated systems.

to accomidate heeadphones with a single 5-pin face jack, you would need at least 3 dongles.

1: 5-pin to 4-pin so the k1000 camp would be happy.
2: 5-pin to dual 3-pin xlr, so the more comon aftermarket balanced will be happy.
3: 3-pin to dual 1/4" trs, to accomidate the single ended drive headphones, and ones made balanced with this plug...

i would personally prefer wiring everything up inside the amp with wire of your choice (includes the mildly absurdly epensive sterling silver, and cardas wires) than building however many dongles... the parts count & price for the "many dongles" would be significant, where the 3 panel mounted jacks AND silver wire would probably come out less.

FWIW, poeple dont think highly of dongles. even if the "dongle" is simply insiude of the case as is comon on MNAY computer parts, people prefer that one to the visible dongle. the dongle is not a sexxy piece of gear. but there is something hot about sticking a plug straight into a jack.

 

[spendorspain]

Thank you for your suggestions.

I think I'm going to use a 5-pin XLR male plug in the headphone cable and a matching latching female panel socket in the amp frontplate.

Why 5-pin? Because perhaps I'll use a shielded cable and thus pin1=L signal out, pin2= L ground, pin3=shield, for connecting only at the "amp out" end a possible overall copper braid over the 4-conductor headphone cable (if there is not such shield, pin3 won't be used), pin4=R ground and pin5=R signal out.
I prefer only one 5-pin connector and not two 3-pin XLRs, because it is neater, specially at the headphone cord end.

Why XLR? Because of the multiple-pin capability and not-so-big size of the standard XLR connectors (the lovely Switchcraft "Tiny QG" mini xlr mentioned in other threads are too small). You're right the SpeakOn are bulky and too unorthodox for this use.

And why a latching female panel socket? Because it is safer not to have the live output contact pins directly exposed to touching, as it occurs in a male socket, and because the latch prevents any accidental disconnection.

To allow the use of my "XLRd" HP-2 cans with other standard amps, I'm also going to build an adapter with a 1/4 inch stereo male plug (the same Cardas connector I already use) in one end and a latching 5-pin XLR female cord plug in the other, with the ground contacts joined (so the combination HP-2 plus adapter is a standard L, R and common G headphone cable and plug).

I've searching a little in the Mouser catalogue and I've found the Deltron XLR plugs that seem even better (according their specs) that the almost universally used Neutrik. What I think it matters most, they have brass contacts directly gold plated (0.5um Au) without the intermediate nickel layer of Neutriks (2um Ni + 0.2um Au). Nickel plating is avoided by some very good manufacturers, like WBT or Cardas, for sonic reasons (as they explain in their websites).
Have you any info or experience about these Deltron connectors? Are they actually direct-gold plated?

Best regards
Jose

 

[Garbz]

Quote:

Originally Posted by spendorspain And why a latching female panel socket? Because it is safer not to have the live output contact pins directly exposed to touching, as it occurs in a male socket, and because the latch prevents any accidental disconnection.

Lol do you know anyone who's been killed from a line level output

So far even my 140watt amp has failed to exite me while connecting speakers when the music was playing loud.

I'd be tempted to use the male plugs because a) I think they look better, and b) male plugs are used for line outputs typically. But in the end this is designers perogative.

Also comming from someone who's headphone cable is shielded because the only thing lying around was 4m of starquad, don't. Shields are stiff, they make the cable inflexible, and the are not needed at all for headphone outputs. Firstly headphones have a low impedance <300ohm typically, secondly the signal no longer gets amplified, and thirdly any signal you get will be common to both connectors and thus you'll hear just as much noise from your headphones connected using a non-shielded cable as headphones not connected to anything at all

While I don't have experience with the connectors you mentioned I have experience with other XLRs. So far the Neutrik ones are by far the best I've used. Amphenol come in close behind but only for astetic reasons. Gold plating is not what you're after in XLRs. They are great for RCAs to prevent corrosion but XLRs have self cleaning contacts so the pretty much industry standard of silver is as good as it gets for these connectors. Also much of the "bad sound" attributable to RCAs is because of the mechanical designs and interactions of the socket itself. XLRs and DIN connectors from my experience all sound identical provided they are mechanically and electrically sound.