HeadPhones amp project

[isak]

Hi Guys

i want to build the attached scheme amp for the next headphones..
http://www.pioneerelectronics.com/PUSA/DJ/Headphones/HDJ-2000
do you think it will be compatible?
how can i tell the drive load range impedance of this scheme?
what do you think will be the mW output?
do i need to match (VDE/HFE) of the 2SC945 and the 2SA733 on each stage for the output to be equal for LEFT & RIGHT?

i found another shceme over ebay, it seems fare.
http://www.ebay.com/itm/P7SE-Preamp-Kit-Vorverstarker-Headphone-Kopfhorer-Amplifier-Board-DIY-Kit-/291685272834?hash=item43e9cc0d02:g:~0MAAOSwBahVFtVM

i really want the attached scheme will be ok for my needs cause i have all the mention components

thanks in advance.
Isak E.

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[elektrouwe]

[isak]

hi elektrouwe

your probably right, but i was hoping.
thanks for the input!

cheers,
Isak.

[LFLab]

+1

Don't build this without biasing diodes.

the kit you saw on eBay is not bad, Douglas Self himself has a schematic in his book using parallel 5532's to drive headphones, I've built one with a quad OPA4134 per channel, sounds good, but the opamps do get warm, not sure about the longevity.

the other option is using LME49600, a high speed buffer (equivalent to BUF634), expensive, very few parts needed, layout is critical (because high speed), sounds superb.

Cheaper options are using an opamp with follower transistors, but then properly done
You can use BC547-BC557 as a follower, BC327-BC337 (moar power!), or BD139-BD140 (even moar power!).
I'd go for the last option for 30-ish ohm cans.
I have a PCB for it if you are interested (and for the BC327-BC337, but that's untested).
Yves Usson (BC327-BC337):


Gyraf.dk (BD139-BD140):
Here

And then there is this kit from JLM audio, uses either 3 or 4 NE5532 opamp stages (no schematic) per channel: JLM Audio AMP HEAD

[isak]

Hi LFLab

thank you so much for replying, you give me hope
did you manage to build the headphones part only of the Mixout-VC Panner?
its fare easy to build.
if so do you recommend me to use ...
http://www.taydaelectronics.com/bd140-transistor-pnp-80v-1-5a-to-126-bd140.html
and..
http://www.taydaelectronics.com/bd139-transistor-npn-80v-1-5a-to-126-bd13910stu.html
instead of BC327-BC337?
do i need to modify some parts if i change the BC327-BC337 to BD139-BD140?

few more Q's about Yves shceme...
1. what would be the output mW with BC327-BC337 and what would be the output mW BD139-BD140?
2. what would be the drive load range impedance, will it be like the Ebay scheme, say from 16ohm to 600ohm more or less?
3. what would be the Frequency response?
4. your design is based on the Yves scheme? i'm asking cause it dose look similar.

sorry for the noobi questions, hope you can answer my Q's.

thanks again!

[LFLab]

Hi Isak, good!

I haven't tried the BC327-BC337 variant yet, I have boards for it (which require at least one fix ), output of that board will be a few hundred milliwatts, probably.

The BD139-BD140 board works fine, it also has a "single AC to bipolarDC" PSU (MFOS wallwart PSU), so you can use it as a standalone headphone amp.
It has a mistake on the polarity of a few electrolytics, nothing major, output of that board is a few watts (it'll drive a speaker).

Both of these will drive your 36ohm cans fine, I haven't heard the BC327-BC337 version yet, so I can't comment on the sound, but the other one is pretty good.
Frequency response is more than you can hear

I don't think I used Yves' schematic for the BC327-BC337 amp, but it will probably be similar (I actually thought his had the BC547-BC557 pair).

This picture has the BD139-BD140 board for your reference (left top):


And this one the bc327-bc337 (also left top):