My latest modding enterprise

[Andrea]

In the future I may buy another 0HA-REP to mod, but this time with either an OPA2727 or an AD746 in the gain stage. Obviously the LT1363s would stay

 

[Andrea]

To make it clear -- the 0HA-REP is a very capable amp even without any modding. My only small complaint had to do with the timbre, not quite 'intense', as I'd have liked; this was before it being run in properly. Now I wish I had an unmodded one to compare

 

[mrarroyo]

Quote:

Originally Posted by Andrea To make it clear -- the 0HA-REP is a very capable amp even without any modding. My only small complaint had to do with the timbre, not quite 'intense', as I'd have liked; this was before it being run in properly. Now I wish I had an unmodded one to compare

Are you sure you like it? I mean start in the begining and do not leave anything out.

 

[Andrea]

Quote:

Originally Posted by mrarroyo Are you sure you like it? I mean start in the begining and do not leave anything out.

I'm not sure what you mean

That I'm excited with the performance I got, it's sure.

 

[Andrea]

Plus, if something like the PA2V2 is decent, even good, then this amp is stellar and modding it becomes but a subtlety.

 

[Andrea]

Ouch, I just saw that the OPA2727 in SO8 package will only be "available in Q2 2006".

Not that the AD8620 works any bad, eh...! And the LT1363 somehow tries to compensate for the AD8620's slight lack of midrange body. Actually the midrange sounds great as it is, very fluid.

 

[vorlon1]

would an LM 6172 like is in the go-vibe work in the xenos?

 

[Andrea]

An LM6172 no, two LM6171 as output drivers yes instead. They should be totally fine. But IMO the LT1363 performs better with 12V as is the ideal & max. safe voltage for this amp. That was my alternative to the LT1363, but I happened to only have LM6172s and in DIP8 package at hand.




Having been comparing this amp to my Pioneer A-209R (HD650; PJ Harvey, "To Bring You My Love")

I am proud to declare that this is my first amp to ever give the Pioneer a run for all round sonic ability. The more improbable task was having an op-amp based amplifier sound that 'expressive'. The Portaphile (...the Xenos 3HA, some Shellbrook, and a few others) had miserably failed.

The modded 0HA-REP is, for the first time, just about as musically expressive as the Pioneer; certainly it is more evenly balanced across the spectrum, as is expected of a dedicated headphone amp, yet without severely sacrificing dynamics, and perceivably (even) more accurate, yet without harshness. And in comparison - which put my mind at ease - vocals don't sound recessed at all, just a little different - typically opamp-ish - possibly even more nuanced if not entirely 'better' (that would be too much...).

 

[Andrea]

^^^ Sorry for the contorted language

 

[Andrea]

The two chips that look the same are THS4051's (thanks Fliburt for giving me the impulse

). Their place was previously occupied by the famous LT1363's ...

The Texas Instruments THS4051, for those who don't know it already, is a 100 mA output current (150 mA short circuit), 70 MHz, 240 V/us chip. It is specified for both +/- 5V and +/- 15V. At the lower voltage it still has a hefty 75 mA output current. In the Xenos it is powered with +/- 6V.



First impression -- This is even better! There's the fullness that previously lacked a bit. The bass is fuller and rounder (no more 'bony'), now really visceral. The midrange (playing Tom Waits, Real Gone) finally sounded really full bodied. Resolution & texture is at least on par, perhaps a touch better. The overall feeling is pleasantly darker because of the improved 'body'. The midrange is very smooth. Definitely I'm not planning further experiments. This amp has reached its acme

 

[Andrea]

Note that, though it can't be seen easily in the pics, pin 8 of both THS4051 needs to be lifted in order that it doesn't make contact with the trace beneath, just like with the LT1363.

 

[Andrea]

I couldn't have any listening today. What a pain

 

[Andrea]

The amp let the HD650 sound absolutely gorgeous with Tom Waits, "Blood Money". The midrange and the overall refinement were..... flawless.

 

[Andrea]

It's clear for me that the THS4051 chips are very audio-friendly (as the datasheet let me expect). Part of their exceptionally good sound quality must be related to the highish, 8-9 mA, quiescent current.

 

[Andrea]

I went through a few of my most familiar records and the impression could only crystallize: excellent.

I'm already starting to think of what effect a DIY upgraded power supply would have...