Good class A headphone amp to build?

Status
Not open for further replies.
Jump to Latest
#21
Steve Eddy said:
The cheap consumer plugs do. Not the real deal. Unfortunately the real deal doesn't work with the cheap consumer jacks.

se
Click to expand...

nice to know - but practically useless given that the several $300-$500 dynamic headphones I have came with the straight body, recessed insulating spacer version
(and one actually was a screw-on 1/4" adapter over the 1/8" TRS that the cable was actually terminated with)

I do agree that the B22 is a bit over the top for 300 Ohm headphones

I listen to my HD600 straight from the PC soundcard, my Sansa Clip+, my universal player headphone out (NRC4556 running from +/- 10 Vsupply)

more often than I fire up my Class A paralleled push-pull TPA6120 monster

I do have the more sensitive SA5000 if I were worried about clipping with the lower V sources
 
#22
jcx said:
nice to know - but practically useless given that the several $300-$500 dynamic headphones I have came with the straight body, recessed insulating spacer version
(and one actually was a screw-on 1/4" adapter over the 1/8" TRS that the cable was actually terminated with)
Click to expand...

Yeah. Because virtually everything else out there will survive having their left and right outs shorted. 😀

I do agree that the B22 is a bit over the top for 300 Ohm headphones
Click to expand...

I think it's a bit over the top, period. I simply don't see 100+ parts and components for just one amplifier channel being necessary short of a cynical numbers-playing game. Instrumentation, sure. But not an audio amplifier.

I listen to my HD600 straight from the PC soundcard, my Sansa Clip+, my universal player headphone out (NRC4556 running from +/- 10 Vsupply)

more often than I fire up my Class A paralleled push-pull TPA6120 monster

I do have the more sensitive SA5000 if I were worried about clipping with the lower V sources
Click to expand...

Yeah. It doesn't take much to light up the 600s. But then you've got the power pigs out there like the HE-6. Though it seems HiFiMAN has finally got on board with some higher sensitivity offerings like the 1000 and Edition X.

se
 
#23
I managed to fit both a dac and an ebay headphone amp into one chassis, all fits in my desk drawer. The amp I used was from Weiliang model E5, is a variation on a JC2 but with some tweaks.
There is an isolation transformer and a power conditioner that supplies it. The sound is delicately detailed with plenty of bass slam as well. I have also replaced the capacitors that came with it.
The amp has a protection circuit, and even though I always turn it off before unplugging the phones, it's nice to know that there is some defense against a shorted output.
It's been running for a few years now.
 
#26
I recently finished this JLH headphone amplifier from bay.

JLH 1969 style headphone amp

It's 1969 style with single power supply, and output capacitor. Another surprise! It comes with SMD resistors! It was PITA at first to deal with SMD, but after a couple, I kinda enjoy soldering them.

I just chose this for no reason, but the outcome is very surprising. I have Benchmark DAC 1 as a DAC and headphone amp, and this beats its headphone section with all the parts supplied by the seller.
I wonder how good it can be if I replace the parts with better ones, so I am going to order another. Or is the complementary versions mentioned here earlier might be even better? But I heard those have DC offset issue.
 
#28

Attachments

  • HA-Class-A.png
    HA-Class-A.png
    97.2 KB · Views: 1,488
#30
I have a Sennheiser HD598 headphone currently used with the headphone amp section of a Tianyun Zero DAC with very good results. Just for the fun of it, I decide to build a solid state separate headphone amp. I found the YuanJing assembled board at a very good price.

https://www.yuan-jing.com/e19-class-...hone-amplifier

I was attracted to its all descrete, fully symmetrical, MOSFET output section design. It has uPC1237 Speaker Protection Chip. The producer indicated high quality parts are used. But I cannot find any schematics or circuit information.

I picked it over the Lehmann or Beyerdynamic clone. I already ordered one and it should be here in 2-3 weeks. Anyone has tried it before?
 
#36
phase said:
This is the one I have been using;

New Assembled Board E5 Class A Headphone Amplifier Alps RK27 HiFi Weiliang | eBay

Schematic is here, as supplied by the producer;

http://www.diyaudio.com/forums/headphone-systems/221480-my-e5-class-hifi-headphone-amp.html

I replaced every capacitor on the board, not sure if that wasn't a bit overkill, but I definitely like the way it sounds.
Click to expand...

Thank you for the links. They are very helpful. Do you have any instruction on bias adjustment or DC offset?

It seems to me that WeiLiang had not come back to this forum for a long time. I wonder if the E19 board has any link to his earlier work on E3/E4/E5?
 
#38
I have left the pots alone, since the dc offset wasn't much, and the thing runs about as warm as I would want, keep a slow running fan on it anyways.
I swapped the Panasonic FC 220uf out for some 100uf Silmic ARS, doubled up on each side of the board, got rid of the film caps that were provided for some Wima FKP1, and finally the main filter caps were replaced with Mundorf AG. It is mounted in a steel case along with a dac, which was also upgraded.
I liked the idea that it had been developed, and offered a decent protection circuit, was direct coupled.
I dont recall the E19 having been around when I bought mine a few years back, don't know anything about that one, but it looks similar...
 
Last edited:
#40
savinalexandru said:
Hi,

Recommend you a O2 headphone amp. Finish it a couple of days ago for my HD600. Sounds really nice and clear, didn't tired me for 2h of continuously listening.
I'll throw in 2 SSLV1.1 for power supply... batteries don't come cheap.

If still want a mosfet class A, you will find a nice project on Class A headphone amplifier by Kevin Gilmore

Rgs,
Alex.
Click to expand...

Alex, the Kevin Gilmore design you linked does not have a MOSFET output stage.

Output stage is a symmetric quartet of parallelly connected emitter followers Q7-Q10 and Q13-Q16. It has gain 0.9 and idle current about 15mA per transistor with power supply +/- 16V. It makes transistors relatively hot but not too much for need of heatsink.
Click to expand...

It uses small signal bipolar transistors in quadruple parallel to support a 60 mA total idle current. It may not be in Class A except with high impedance headphone. It does have a JFET input stage.

The use of small signal bi-polar is unique. The author did not explain its advantage other than they don't need a heatsink.
 
Status
Not open for further replies.
Top Bottom