suggestion for a 200$ headamp

[murphythecat8]

hi everyone.
I dont want tube necessarely as my budget might not allow.
I use some cheap ath m50 and will eventually get hd-650.

I have 200$ for the whole project.
which project would fit my needs?

Is this fred cmoy jrc4556 ra-1 good enough?

[jcx]

NwAvGuy: O2 Details

or just buy it:
JDS Labs - Objective2 Headphone Amplifier

many more hobby project amps have been presented in the past:

Originally Posted by jcx

how can these threads get to over a dozen posts without a pointer to the Headwize archive?

HeadWize Library - Projects

site is dead, but the archives are required reading for aspiring headphone amp diyers


head-fi.org has a diy forum - beware the relative lack of engineering knowledge/discussion, excess fanboyism compared to here - but some info

List of DIY headphone amplifiers

[Telstar]

If you go cheap on the casework, you can build most DISCRETE designs, such as Marsh, CK2III, etc.

[murphythecat8]

Originally Posted by Telstar

If you go cheap on the casework, you can build most DISCRETE designs, such as Marsh, CK2III, etc.

okay, the o2 is not a discrete design, so will be less good right?

what is the cheaper to build, the CK2III or Marsh?

[jcx]

while "discrete is superior" is an entrenched Audiophile meme - they never placed a "expires by date" on it

O2 is likely indistinguishable in DBT against any other objectively good, flat frequency response, low output Z, low distortion design regardless of technology, within its I,V output capability

but similar chip count composite/multiloop amplifiers, using "better" speced op amps released in the past decade or so are really untouchable at line level audio today - if accuracy is any part of your hifi amplifier definition

isolated bipolar, SiGe, GHz semi processes, advanced internal circuit designs by big companies competing for modern telcom, imaging market applications have taken a big step forward from the era of 4556, 5534

even $5-10 for op amps shouldn't blow a $200 budget



I quite understand as a circuit designer the greater enjoyment I derive from discrete circuit design - I just don't confuse that with being able to reach the performance specs of properly applied best in class modern monolithic op amps anywhere their input noise, output I,V capabilities meet the application's demands

[Telstar]

The main issue of opamp based headamps is the lack of current, which makes them not very suited for low Z 'phones.
Now, the hd650 is NOT low impedance and the o2 would drive it fine.

About how it sounds, I don't really know. I don't have any friend with one to do an AB test.

My suggestion to go discrete was dictated by the budget of the OP and by the fact that this is a DIY forum.
Btw he can also buy a shiit M-something (forgot the name) for 99$.

[jcx]

the O2 choice of 4556 is driven by the +/- 70 mA output spec, and that is doubled by paralleling the 2 op amps in each chip, per channel - so +/- 140 mA peak should be available

M50 38 Ohms absorbs >300 mWrms @ 140 mA peak drive

unfortunately their site doesn't qualify their 99 dB sensitivity with the reference level, the old standard of 1 mW or 1 Vrms as is becoming more common

99 dB +25 dB re 1 mW is ridiculous @ 124 dB SPL

but even if we go with +17 dB re 1V, for 116 dB SPL clipping level with O2 driving the "low impedance" - thats not so shabby loudness wise either


but my default choice of a modern output drive op amp is the TPA6120 (rebadged THS6012 DSL driver chip) 100 MHz CFA op amp with 400 mA output current and ppm distortion, designed to drive DSL transformer's 25 Ohm impedance - and I have paralleled 2 of them...

[dry joint]

CMOY not very good, and if the rA-1 is the Grado one its stupidly costly. I've had a dozenish headphone amps and messed about with mods, psus, valves, kits, off the shelf, essentially I've tried most sensible approaches except high voltage tubes, and my conclusion from 14 years of this is: if you have a stepped attenuator and a PSU per channel, any decent solid state amp will sound very good and blow away affordable shop stuff. People that are invested in one design or other will claim superiority or that practical perfection has been reached, they aren't right but aren't that wrong either.

If you want to build a kit look for one that lends itself to seperating the left and right channel power. If you want a ready built amp see if the case can accomodate a stepped attenuator or other fancy volume control, the latest version of the Neco MOSFET has a psu per channel but could do with modding for a stepped attenuator.

The Panda kit on ebay is very good with HD600, so should go well with HD650. Best budget for a box for the transformers and one for the amp, will come in at under a bit $200 unless you go for boutique upgrade parts in which case it your own fault.

The O2 is highly rated but is smd and if pre-made may be difficult to change to a larger volume control. An alternative would be Low distortion ( 0.0001%!) preamplifier headphone amp ! | eBay
Get free sample chips from TI and the thing could easily come in for a $100.

[Telstar]

Originally Posted by jcx

but my default choice of a modern output drive op amp is the TPA6120 (rebadged THS6012 DSL driver chip) 100 MHz CFA op amp with 400 mA output current and ppm distortion, designed to drive DSL transformer's 25 Ohm impedance - and I have paralleled 2 of them...

Now this is interesting
My HP peaks about 440mA

[dry joint]

The tpa6120 is surface mounted with 20+ legs, there are lots of designs for headphone amps using it here and around the net.