[ORDER] 4hp, the 4-ear headphone amplifier in ... 4hp

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[ORDER] 4hp, the 4-ear headphone amplifier in ... 4hp

Post by av500 » Sat Jun 11, 2016 10:17 am

UPDATE: see ordering information and BOM below...

Introducing "4hp", the 2+2 headphone amplifier module in ... 4hp!

Compact and skiff friendly, only 35mm deep.

I made this because I needed something to drive headphones for the Happy Knobbing 2016 modular meeting. two separate channels each with their own volume knob, so you can share your bleep bloops with a friend!

The input jacks can be either wired as "through" so that you don't need a mult to pass a signal to the headphones - or you can wire them for two separate headphone channels. Also, jacks should be normalled left to right so that a mono signal shows up on both ears.

The amp is designed to "blow your ears away", the (dirt cheap) NJM4556 opamps used can deliver up to 200mA per ear. The amp has unity gain because your typical modular levels of 10Vpp are enough to drive all kinds of cans. If needed one can add gain by cutting some PCB traces and adding SMT resistors. In the standard BOM, the internal 68R balancing resistors limit the current to about 150mA per ear at 5V, but they can be reduced down to 1R if needed. See more about the NJM4556 here: http://nwavguy.blogspot.de/2011/07/o2-d ... ocess.html

You can even drive small ~8Ohm loudspeakers at normal "room" level

If you want to reduce the gain you can wire a resistor from the jacks to the PCB, effectively limiting the potentiometer range. Depending on your headphones, you might want to do that in order to get a bit more range on the knob. Potentiometers are 9mm dual type, they are not as common but available from some sources like Smallbear:

http://smallbear-electronics.mybigcomme ... -pc-mount/

If you cannot get audio taper pots you can also use linear taper and install a resistor across to change the taper as explained here:

http://sound.westhost.com/project01.htm

The output is DC coupled so that there is no need for huge coupling capacitors, but the input is AC coupled to prevent frying your headphones with DC biased signals. You can also short/omit the coupling caps if you want to use this as a DC coupled CV driver for whatever you want to connect.

ImageImageImageImage

full kit:

Image
Last edited by av500 on Sun Sep 10, 2017 5:22 am, edited 5 times in total.

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Post by av500 » Sat Jun 11, 2016 10:18 am

bill of material, build guide, schematics and panel drill template

Mouser cart: https://www.mouser.com/ProjectManager/P ... d2480b63ca

Mouser does not have 9mm dual potentiometers, here are some sources:

http://smallbear-electronics.mybigcomme ... -pc-mount/

http://www.ebay.com/itm/280877943574

http://www.ebay.com/itm/181177919204

http://www.ebay.com/itm//371729007802

http://www.ebay.com/itm/181177919836

http://www.ebay.com/itm/131906155606 (needs desoldering)

these might also work if you cut away the tabs and drill out the mounting holes to 9mm:

Alps RK09L12B-LOG100K from e.g. http://www.reichelt.de/6mm-Pots-stereo/ ... &OFFSET=16&

(NOTE: in order to see the attached documents, you need to be logged in to muffwiggler.com)
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Last edited by av500 on Fri Oct 05, 2018 7:34 am, edited 10 times in total.

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Post by av500 » Sat Jun 11, 2016 10:19 am

ORDERING INFORMATION:

PCB + panel: €23 + €5 shipping worldwide

full kit: this has been discontinued for the time being, (was €55 + €7 shipping worldwide)

worldwide shipping as a tracked and registered letter

to order, send me an email to vp (at) vpme (dot) de with your full shipping address, then I will reply with Paypal details.
Last edited by av500 on Mon May 25, 2020 3:12 am, edited 5 times in total.

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FetidEye
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Post by FetidEye » Sat Jun 11, 2016 10:25 am

here be interest

euromorcego
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Post by euromorcego » Sat Jun 11, 2016 11:51 am

here also interest!

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Post by puzo » Sat Jun 11, 2016 1:35 pm

yes please

vinylvandal
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Post by vinylvandal » Sat Jun 11, 2016 2:48 pm

i would be interested in this!

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Post by Suf-fuD » Sat Jun 11, 2016 5:32 pm

interest here too...

basicbasic
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Post by basicbasic » Sat Jun 11, 2016 6:37 pm

Me too me too! :hyper:

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adnauseam
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Post by adnauseam » Sat Jun 11, 2016 6:55 pm

Awesome! I'd buy one or two

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antf4rm
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Post by antf4rm » Sat Jun 11, 2016 7:42 pm

Looks great! Nice work.

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BananaPlug
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Post by BananaPlug » Sun Jun 12, 2016 11:10 am

:tu:

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Post by peloazul » Sun Jun 12, 2016 8:01 pm

:tu:

hsimonis
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Post by hsimonis » Mon Jun 13, 2016 2:43 am

interest here as well

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av500
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Post by av500 » Mon Jun 13, 2016 3:34 am

one PCB sent off to a trusty beta-builder today. panels will be ordered. heads will phone (or ring?)

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infovore
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Post by infovore » Mon Jun 13, 2016 7:17 am

very nice, very interested. will it be possible to re-implement the schematic for our own use?

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av500
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Post by av500 » Mon Jun 13, 2016 7:20 am

infovore wrote:very nice, very interested. will it be possible to re-implement the schematic for our own use?
I don't think I did anything too clever with the schematics, so sure :)

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infovore
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Post by infovore » Mon Jun 13, 2016 10:27 am

av500 wrote:
infovore wrote:very nice, very interested. will it be possible to re-implement the schematic for our own use?
I don't think I did anything too clever with the schematics, so sure :)
Ah, cool - might see if I can make a little 1U SMD version...

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oberkorn
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Post by oberkorn » Sat Jul 09, 2016 7:46 am

looking good :tu:
will take one PCB/panel set when you are ready

vinylvandal
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Post by vinylvandal » Sat Jul 09, 2016 9:29 am

looks really cool. what is the depth of the moduie?

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janost
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Post by janost » Sat Jul 09, 2016 9:39 am

vinylvandal wrote:looks really cool. what is the depth of the moduie?
35mm?
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av500
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Post by av500 » Sat Jul 09, 2016 9:44 am

janost wrote:
vinylvandal wrote:looks really cool. what is the depth of the moduie?
35mm?
35mm! :banana:

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masterofstuff124
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Post by masterofstuff124 » Sat Jul 09, 2016 11:41 am

Ooooo yah im into this!

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Post by av500 » Wed Aug 03, 2016 7:19 am

panels finally arrived - but now I'm away for two weeks, so bear with me for just a little but longer...

Image
Image

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EATyourGUITAR
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Post by EATyourGUITAR » Wed Aug 03, 2016 8:52 am

this is a really nice project. we needed this in DIY.
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