[NelsonVandal]

Hm, maybe a should give it another go. I thougt it was such a big change in tonality to OPA2134 which is exaggerated in the mids/midbass, and AD8620 changed it all back to "normal". Maybe I should try it in the Xtra, because it's a bit too fat-sounding and lacks soundstage and speed. I doubt burning it in will change all this.

Please give some more impressions after further listening. Are you listening with HD650?

 

[Andrea]

I do like a "ripe" midbass and lower midrange... The LM4562 may not have the most bloom in this part of the spectrum, but then again those AD chips don't, as well... If only there was something like a improved OPA2134 from BB... (I don't consider the OPA2107 to be so, at least for a 12V supply)


When I manage I'll say some more about my liking of the all-LM amp. Yes btw, it's with the HD650 I'm listening to it.

 

[NelsonVandal]

I hope the answer to our prayers will be OPA2827. Supply from 8 - 36 V.

 

[NelsonVandal]

Shouldn't it be possible to use DC/DC step up converters in these kind of small amps to boost the voltage?

 

[Andrea]

Some more listening. I think I like the LM4562 more than the AD8620 (that somehow it resembles, to me) with the LMH6654. I delivers a slightly nicer midrange, better bass, perhaps better treble.

In short, it all sounds quite good. Yet...still not perfect. I'm positive that chips like the AD9631 and the AD8397 would pair with the LM4562 better and give out what now is missing... a bit of "3" flavor, especially. I'm not kidding... the 'numbers' are a key to an effective pairing of different op-amps I've realized.

So if I keep the LMH6654's in the new 0HA-REP I'll use the LT1361 for preamp; if I keep the LM4562 instead, one of the two above mentioned chips. I think.

 

[Andrea]

I was just one step away...

So now I've the AD9631's too in the Xenos. Still have to listen, but one thing I can tell for sure: powered with 12V, they don't run cool

The top of the amp gets a bit warmer than even with two AD8397's inside. I think I'll keep the voltage a little lower, i.e. 9V for now, and maybe 10V later.

 

[Andrea]

I'm left absolutely SPEECHLESS.

This is IT. The sound has suddenly turned heavenly, breathtaking, perfect.

And what do I care if it gets a little bit warm, when it sounds this good. I'll keep 12V (previously I was overly cautious, I believe).


The first two songs of Beth Orton's Central Reservation, like all of an usual favorite, Rainy Day Music by Jayhawks, suffice to prove that this is the most perfect sound my HD650 has ever delivered.

edit- forgot to say that I've made the AD9631's to work at unity gain by removing the 1K resistor going to ground. This way the overall gain is perfect for my needs, and perhaps the AD9631 is even more fine tuned(?)

 

[NelsonVandal]

This is weird. The AD8397 went out from my Xenos. I'm never going to get used to the Analog-sound. It's harsh and fatiguing, a nasty colouration. I don't even bother to burn it in. I'm using LM4562 again. But this time with output buffers bypassed. It sounds good. I hope it's just not a honeymoon, because now my PCB is starting to wear out. There's still some treble colouration, like I said before like Kodacolor or Fujichrome, like the sun always shining. Still a bit hollow and larger than life in the mids. But... this is more fun than both Analog and (cheap) Burr-Brown.

In the specs it says "Easily drives 600 ohm loads". I'm not sure if I need output buffers. Maybe i should go for Sijosae's discrete buffers.

 

[NelsonVandal]

PS. Xtra with bypassed input stage sounds just as clear and fun but with less colourations. To my ears that is.

 

[NelsonVandal]

Silly not to think of it before. The Xtra acts as a buffer now since the input stage is bypassed. Xenos with Lm4562 plays better through Xtra than straigt out with bypassed buffers.

 

[Andrea]

If you want to hear how good the LM4562 can be in the Xenos, try it with the AD9631's

 

[NelsonVandal]

OK Andrea, they're quite expensive and I don't have the guts to order more free samples from Analog. Where did you get yours? Are you sure it's not that harsh and fatiguing "Analog-sound"? I don't want the amp to be brighter. I find LM4562 a bit thin and bright. Do you find AD9631 neutral, bright or warm in toanlity? To my ears the LMH's seems to be too bright. Do you think it's sane (and safe) to try sijosae's discrete buffers?

The board is a bit messy because I have nothing appropriate to clean it with.

 

[Andrea]

The AD9631 counterbalances the LM4562 very well, with its full and comparatively warm sound, without apparent treble aggressiveness.

Although the Xtra with the same op-amp sounded still more transparent thanks to the discrete buffers.

I say "sounded" 'cause now I've the AD8620 in the Xtra and it's there to stay.

For the AD9631 I got two samples from AD. Beware that it warms up a little. You may want to try the THS4051. It's another chip that goes very well in the Xenos (wish I could compare them) and it has much of the typical BB sound. Note that the specified minimum supply voltage is +/- 4.5V.

 

[NelsonVandal]

Andrea, now I'm awaiting your review - which amp's the best - your modded Xenos or modded Xtra?

Your comments about LM4562 in Xtra supports Magsy's and mine impressions of the "hollow, not very neutral, LM-sound", I think.

You really should try bypassing those damned things (input opamps), they all seem to colour the sound.

 

[Andrea]

Think of it, I do like the OPA2134

I think I'll leave it in, and buffer it with two AD8057's, in the new amp. If I'm not happy enough, I'll replace it with an LT1361.


At the moment, the Xtra is the better sounding amp. But I'm a bit perplexed about these AD9631. After all, the LMH6654 may have sounded more transparent/clear, without the hotness...