8 channels headphone amplifier

[mata_haze]

Hello everybody,
I have been doing some research but I cant seem to find anything like this around.
Is there any DIY version of the hearback system or the Aviom system but in an analogue way.
I have seen one in a studio in London which was fully analogue with EDACs connnectors and honestly it sounded REALLY good. I think it was an english brand too.

I am surprised nobody from the forum have come up with a PCB or something...

Mattia.

[12afael]

I started a kind of clone of the rane, I don´t remember if it have 6 or 8 outputs. If I remember the pcb design is complete (eagle). I will take a look at home.

if someone is interested in turn this in a project, I would be happy to help.

best regards.

[mata_haze]

yes I would be.
I am also in to help you if you need anything. but apart from having multiple outputs, can it also act as a headphone mixer with lets say 8 separate inputs?

Mattia.

[Rochey]

MAta,

this is a project I've considered many times with Expat Audio. (using ADAT as a backbone to transmit channels over cat5 cable, then a standard 8ch DAC in each pod).

I already have partial schematics - but never got 'round to productizing it. I'll happily do so if there's interest from more than just you

Cheers

/R

[mata_haze]

to be honest I was looking for something completely analogue ...
but this could be interesting too!

perhaps someone else will join the conversation and show some interest?!

Mattia.

[Rochey]

Mata - the joy of Cat5 is that it's incredibly cheap, connectors and cheap etc.

Making an analog source for it is quite simple. A bunch of PCM1808's, running into an ADAT generator, then into an RS485 transmitter would do the trick nicely.

Hi-Fi isn't the challenge here. Giving musicians a custom mix is what's tough

[mata_haze]

I see your point!
well I can only say let's see what you have got and people chime in to show interest!

Mattia.

[12afael]

Rochey, that sound interesting maybe we could add it as an alternative in the PCB.

I will post what I have and we can work over that.

[analag]

to be honest I was looking for something completely analogue ...
but this could be interesting too!

perhaps someone else will join the conversation and show some interest?!

Mattia.

Single channel shown.
JFet input opamp recommended, depending on opamp voltage rails can be increased...should be tweaked.

[mata_haze]

thank you analag,
it might be interesting to use the front end of the opamp for multiple inputs like a summing mixer.

Do you think that connecting multiple of this amp in parallel will be ok?

MAttia.

[okgb]

It's something you can use whenever recording a band or more than one person at a time
I have been using cheap little mixers + mix & individual aux sends , but digital sounds fine
for the purpose

[Brian Roth]

While I've never personally used this system, Furman sells a package which supports four mono channels and one stereo channel at each of the headphone boxes.  I'm almost certain it's totally analog, although each headphone box is connected via two Ethernet cables (RJ-45 connectors).

http://www.furmansound.com/pdf/manuals/HDS-6_HR-6_manual.pdf

Best,

Bri

[12afael]

this is what I have, the project is from 2005, it need some work I think the pcb is 30x10 cm. It should be posible to reduce the size.



here is the schematic. I think rane have also the schematic at their web.

http://www.twin-x.com/groupdiy/albums/userpics/headphone_amp_sch.png

I can`t upload the eagle files at twin-x, It need some work so I`m not sure if I want to send it to the groupdiy email. let me know if someone want the files.

[mata_haze]

Hello 12afael,
thank you very much this is great.
I must say that my idea was for a so called "personal mixer" like the aviom or the hearback and what Rochey is saying is that it's easier to implemente it with ADAT on (which carries 8 channels per line).
please have a look at this:
http://www.aviom.com/AviomApplications/Monitor-Mixing.cfm

http://www.heartechnologies.com/hb/hearbackintro.htm

so there is a bit more to it than just headphone amplifier per se.
having sayd this both Rochey and analag suggestions sound (and look great)...I suppose in the chase of analag circuit we could add 8 potentiometers before the Fet op amp and create therefore a summing mixer (which is indeed what I am looking for) so that you could use your Aux sends from desk to feed the personal mixers and have each musician to tweak it at their own personal taste.
the trouble I see with this is that when the personal mixer is (let's say) 25 meters from the control room the signal that will get to the pots will probably be so degraded that will make it unusuable.
Also connecting multiple of these personal mixing desks in parallel (for when you have 10 musicians,because,in my view, there is no point of implementing such a system for a vocal booth) will cause the resistance seen by the control room mixing desk to be very low with all the problems that this implies.
after these considerations (I am mainly thinking loud here, so people please do join and correct me) I think Rochey solution (or even OKGB one !) are possibly the best!
If I could only remember this brand I saw in the studio in London...I shall call the owner! (any londoner have been to the fish factory in Willesden lately?!)

Best,
Mattia.

[12afael]

I remember Frank at the rehearsal room of his studio have something like that with small 8 channels mixers.

this company have some cool stuff for rehearsal.
http://www.aviom.com/

let me know if I can help with something.

best regards
Rafael

[analag]

http://www.groupdiy.com/index.php?topic=47121.0

This is how I did my summing box. When it comes to the headphone amp, using a nice discrete output to drive the cans just sounds better to me especially when pushed. Personal preference I suppose.

[pucho812]

if you want to go all analog, buy  some mackie, behringer or other small mixers. Then wire them up. You can try passive audio splits, so far I have passively split 20 mixers before without sound loss but the the cable lengths was not real long long. If needed be add in some distribution amps before you send out your channels. It can get expensive to do but it would be all analog. Or you purchase things like the mytek headphone system which is all analog, or the more expensive more me system by manley.

[sodderboy]

I remember someone did the Mackie/Behringer route here and used ribbon cable under carpet to run the audio.  It worked for the run lengths involved.  I was skeptical regarding noise and longevity.  Ribbon cable wired to TRS would not last a week in a heavily used studio.
mcminone.com has some killer prices for Behringer and Xenyx these days.  I saw a 5 or 6 input 2 bus mixer for $50.  With prices like that you will spend more for the wiring than the equipment.

I have installed most of the analog and digital personal mixers and can nitpick specs, sonics and performance.  HEAR, AVIOM, and Furman all last well in heavily used studios.  Mytek suffers from abuse because it connects with 16 pair and DL's and no one pays attention to bent pins and loose connector housings.  I only saw Nemesis, the UK system?, at Power Station and it was always perfect given the tech staff all over it.

The client is the star, but I have never seen more than eight individual channels used on any of these systems with rock, classical, jazz, advertising, etc.  It is usually stereo mix, multiple more ME's, and sometimes talkback.  It totally beats distributed stereo cue systems, but the fewer choices the better.

DIY is cool, but there are huge diminishing marginal returns when it comes to something like a cue system.
Mike

[pucho812]

I saw these guys at winter Namm, it's similar to musikmesse. Anyway the mixer is not inexpensive as it runs around 650.00 dollars per mixer but it is built with solid metal and is not plastic like an aviom and the like.

check out the elite core  audio pm-16 (mixer) and the distribution.

http://elitecoreaudio.com/node/1425

[guy_4]

Hi Mattia,

"I have seen one in a studio in London which was fully analogue with EDACs connnectors and honestly it sounded REALLY good. I think it was an english brand too."
It was probably a NEMESIS Cue system.
Every station was 8 stereo channels, with a master volume for two headphones, and a 3 band EQ.  Also an integrated talkback system.
An interesting concept, with a nice look, but a terrible design.
Plagued by hums and oscillations everywhere, totally unreliable.
We had bought an 8 stations system in a studio in the 90's.
I had to fully rebuilt the power supplies units and make a lot of modifications in the electronics to get a functional system.
Better to start with a new design !
Best,
Guy