4 Way Headphone Box [Need help with circuit design]

[Megabunny]

Let me open with, I know that I can buy one of these super cheap online.  I want the pleasure of making mine.

I Have a Balanced Audio Source in the form of two 1/4" Jacks.
But only 1 headphone port. I need more headphone sockets.

so I have a rough idea of what to do, but I can't think of a way to include volume control.

see Attachment for my base idea. it has 4 ports now but 6 or more would be ace. I'm not against using power, i just dont know how to implement it.

any help would be greatly appreciated.

THANKYOU THANKYOU THANKYOU.

Mike.

 

[ruffrecords]

The big question is can your balanced source drive headphones. What device  is it coming from?

Cheers

Ian

 

[MHanson]

Need more info .... 


What's driving what, where and how?


My first guess is to setup a power amp .... 

Michael

 

[pucho812]

u need a power amp to drive headphones properly especially multiple sets of headphones.

 

[Megabunny]

okay,
I'm using the PRESONUS FIRESTUDIO PROJECT. out puts are TRS Balanced 51 Ω or i have a single head phone out [which i'll add a line in for] which has MAXIMUM OUTPUT 150 mW/CH @ 60 Ω Load


help at all
.

 

[Megabunny]

my first worry was the resistors. to much or to little?

its been YEARS since I did a course on this and I'm only just getting back into it.

 

[Megabunny]

ive got some TDA2030's. are these any good.

 

[Brian Roth]

Decades ago (early 1970's) when I first began working in the pro recording biz, the standard method for driving studio headphone cue systems used a power amplifier driving multiple passive headphone boxes.  Back Then, the power amplifier was typically like a Crown D-60 or D-150....and NOT because you needed the wattage output, but rather the voltage swing to drive medium impedance phones to a (stupidly?) loud level.  My LONG-time friend Rick Chinn explains some of the issues in this article he wrote nearly 15 (!) years ago:

http://www.uneeda-audio.com/phones.htm

The rules were the same in 1972, 1998, and still the same today.

Using a passive headphone distro system, you do require a signal "driver" with a high voltage swing....such as a medium powered power amp.  From there, it's just a matter of distribution, and often times local volume pots at each headphone location. Companies such as Rolls and Furman sell the passive headphone boxes, but the innards are quite simple to DIY.

Of course, nowadays, many newer studios use fancy distros with headphone boxes allowing the musician to dial in his/her own mix (called the "More Me!" concept).  Examples for that would be the Hearback system, higher-end Furman, and even more elaborate systems.  I thought the latter was made by a company called Axiom, but after Googling, that wasn't quite the correct name.....ahhhh...the joys of getting older....lol.  I've seen that higher-end system in only a few studios, but all of the new active systems power/distribute the signals via CAT-5 cables and connectors.

EDIT:  I missed the spelling for the high-end system by only a few letters.  It is made by Aviom. <g>

FWIW, I've installed a few of the 'middle ground' Hearback systems, which seem to work well.  However, the (simple) user boxes are sometimes beyond the understanding of the musicians. 

Best,

Bri

 

[Jarno]

I built a headphone amp using lme49600, simple build (no servo), oodles of drive current. Expensive silicon though. An alternative would be to use several opamp stages with output mix resistors.  those would be the easiest options, imho, very few parts.

 

[bruce0]

I bought a used Rane HC6 for like 50 bucks... It works great... But if you want to make your own, the Rane folks publish the schematic, which should give you some ideas.

The current one is here http://www.rane.com/pdf/hc6ssch.pdf but that includes a switched power supply, the older ones were pretty much the same but with simpler external wall wart supply (AC as I remember but take a look)...

If you want the previous version, Go to discontinued items and look at the older version of the HC-6 series. (you will find manuals and specs there too, which are all pretty good ( when I bought mine used, I check to make sure the specs were up to the specs for the new box, and they are pretty much).  Rane is a really great company... old style... (they publish schematics for stuff they no longer sell!  (Roland take a lesson)))..

They also make an HC-4 (which is for 4 sets of headphones.)... As I remember it is all opamp based....  I could be wrong, havent looked lately.


http://www.rane.com/oldman.html is a deep link to the discontinued manuals list.

bb

 

[RuudNL]

I once needed headphone amplifiers too.
I used (per channel) a NE5534 followed by a BD137/138 pair.
And they are LOUD!

They looked roughly like this: http://www.gyraf.dk/gy_pd/hpamp/HP-Amp.pdf