My latest modding enterprise

[Andrea]

Quote:

Originally Posted by Andrea Stimulated by episiarch's effort, I've been briefly comparing my three best portables (modified Xenos 0HA-REP, Go-Vibe v5, upgraded Portaphile X^3). For laziness, I'll just paste here a part of a post I just wrote in the DIY section. You know what? I've been comparing the Go-Vibe v5 to my modified Xenos (with the AD8620 & the THS4051s), and, not differently from my earlier impressions, I like the Xenos better. Better than my Portaphile, either. It strikes the 'right' combination of midrange mellowness and texture for me, whereas the Go-Vibe errs towards an almost 'innatural' texture, and the Portaphile towards 'butteriness' ( ). It also has the warmest tonality, & some very correct bass & treble. The record I used for comparing was Tom Waits, Rain Dogs -- which contains what are my two-three favorite Tom Waits songs ever, and which I've listened to so many times over the years, through speakers & headphones, that I know I can judge which is the more truthful interpretation of it. uff! (headphones= HD650 ; power supply= Go-Vibe & Portaphile @ 24V DC , Xenos @ 12V DC)

Quote:

Originally Posted by Andrea & also with Lisa Germano, Lullaby For Liquid Pig, the naturalness & the beauty were astonishing. It just enraptures you with the soul of the music. The other two amps can't stand the comparison.

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[MASantos]

Andrea, what is that SOIC chip near the input/output jacks? Which chip is it and what does it do?

 

[Andrea]

Quote:

Originally Posted by MASantos Andrea, what is that SOIC chip near the input/output jacks? Which chip is it and what does it do?

Just go back to page 1, post #8 !

& finally, (promised!!)

the bass is the firmest of the three amps, and feels perfectly balanced.

the mid-treble has some exceptional resolution and harmonic definition -- the guitars in Mark Langan, I'll Take Care Of You were an obvious instance.

 

[Andrea]

I couldn't resist trying a last change.

I don't know... this must have been the most amazingly successful op-amp rolling attempt I've done to date.

The OPA551 has brought the amp's overall refinement, atmosphere (blackness of background and variety of sonic colors), and dynamic headroom 'up a level or five'. It puts in the shade even my AD8397 modded Go-Vibe v5 (although I must concede that for sound signature they're almost like apples and oranges - and I'm more for the BB sound).

 

[Andrea]

Note that pins 5 and 8 of the two OPA551's must be lifted

Another note -- I've seen that the amplifier stage is without global feedback, i.e. the op-amps that do the output buffers are not in the feedback loop of the first op-amp. Rather fancy, I think, and most probably the reason why the OPA551 fits in so well. Maybe also one of the reasons why this amp sounds so good...

 

[Andrea]

Some have said that the OPA551 used as a buffer sounds better than the BUF634.

Although without direct comparisons in the same design, I'm certainly inclined to agree. I've never heard a BUF634 amp deliver all this richness (variety) of acoustic timbres...

 

[Andrea]

The first instance that comes to my mind being my Portaphile, which also has AD8610 op-amps. It sounds much 'duller'; and definitely doesn't sound 'faster' or clearer (maybe the opposite).


One sweet thing about the OPA551, on paper, is that 0.0005% THD+N at 1 KHz while outputting 15V RMS on a 300 ohm load

 

[Andrea]

I did it again.

I had a sparkle of genius... and I removed all three chips to put an AD8397ARDZ in the place previously occupied by the AD8620. Then I removed a few SMD resistors, added a pair of jumpers and... my Hornet clone was ready

The design has all that the AD8397 wants -- balanced currents on the op-amp's inputs, bypass caps, limited bandwidth, & ground plane on the lower side of the pcb.


So far I've only tried if it works, and it does.

Later I'll listen to it in its current environment, that is, my PCDP and the HD485.

 

[Andrea]

P.S. This is definitive.

 

[Andrea]

It works perfectly.

DC offset is between 3 and 4 mV on both channels.


I'm glad I did it, since it has allowed me to understand the 'sonic nature' of the AD8397 better. The sound is very interesting. Fast, powerful & deep bass, extended and subtle treble, clear midrange.

But it lacks that last bit of magic. I preferred the AD8620 + 2x OPA551 combination, for its richer, more emotional tonality; and probably a little more airy sounding.


Btw -- the AD45048 is NOT the AD8397

It's very similar in most ways, but different enough in an important way for me. It's a warmer tonality; perhaps a little smoother too. Tonality wise it's much like the AD8620 + OPA551 ...

 

[IEATTEFLON]

What is your favorite chip of all time?

 

[Andrea]

Quote:

Originally Posted by IEATTEFLON What is your favorite chip of all time?

I'll give it a try...


single chip amp -> AD45048


buffers -> OPA551 & HA-5002


op-amp -> AD8610/20 is one favorite

 

[Andrea]

Forgot to say I also definitely like the THS4051.


Also the AD8397 is really good. Btw, I'm happy to have it in my Xenos - it makes an excellent solution for battery use. So the nice integrated battery charger would be put to work

...and I've had one brand new 9V 280mA NiMh battery for a while now

 

[IEATTEFLON]

You seem to have a lot of success with the ad8397 where the pint/mini3 project met many problems with that chip. The xenos must be well designed to just accept the chip like that.

 

[Andrea]

Quote:

Originally Posted by IEATTEFLON You seem to have a lot of success with the ad8397 where the pint/mini3 project met many problems with that chip. The xenos must be well designed to just accept the chip like that.

afaik&u (as far as I know & understand) the problem with the Pint & such is all in the voltage divider & ground channel op-amps which must work at unity gain... And, I might add, in the obstination not to use a small series resistor on the output

And yep, the Xenos is very well designed for itself

(btw, note that it's designed for either the OPA2134 or the NE5532, the latter being a bipolar input op-amp, hence the balanced input currents).