[nanchangbob]

I've been needing a good quality headphone amp to drive my HD-600's.  My Creek OBH-11 has been a bit disappointing.  Trolling through the posts I came upon the Lehman Linear and later the Lovely Cube.  I'm working and living in China so I starting looking at the Chinese Ebay/Taobao.  I found the boards that go with the lovely cube but found a circuit board that was a little bigger and looked to be of higher quality then the lovely cube.
 
I had about half of the parts on hand which included the 50W transformer, Riken resistors, Wima MKP-10 1.0 uf, and the Mills `10 Ohm for the output..  I ordered the case and some misc parts on Taobao and got the transistors, power supply caps, IRC signal path resistors and op-amps from Digikey when I was visiting family this summer in the States. I added the stepped attenuator. "I always prefer them to Alps pots".
 
I started with dual OPA134 op-amp's and then several other op-amps but I am sticking with the LME47920HA.  Will do some experimenting with class A bias soon.
 
So how does it?  I've been sitting with a smile every evening for the last couple weeks.  Sound stage is wide and the information that is coming through is remarkable.  Bass is well controlled.  I bought an Objective 2 pcb in the States and will build that soon for comparisons.  System used includes the Sennheiser HD-600 Mogami W3106 wire and Esound Reference Platinum CD player.
 
I'm not sure how it compares to the original Lehman or the lovely cube? I only have 2mv DC offset and it sounds great. Best of all it was fun to build.

 

[thecourier]

From the op-amps you have tried, was the OPA2604 on the list? 

 

[nanchangbob]

I have the OPA2604 but I haven't tried it yet.  I will try the others I have as well.  I've just been enjoying the amp.  I also will tried the Class A mod in the next couple of days.
 

 

[nanchangbob]

I've been trying out the OPA2604 and I made a couple of bias adapters.  The 2604 is nice and interesting.  Very musical and a nice sense of front to rear placement. The LME 4790HA has a little more extension on top and bottom but not as musical as the 2604.  I found that I prefer the sound with about 4ma on the class A bias best.  When I go higher it on the bias I don't like what it does to the sound.  I also like the LM4562 it has a nice balanced sound to it.  I wish I could put all the best qualities together.  Maybe the OPA627?  $50 * 2 is a little stiff for me to try in Op-amp rolling.  All my chips were bought from Mouser so I expect them to be good.