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LD Micro Tube, ah tubes at last. . Buff634 bypassed - Page 2

post #16 of 173
Thread Starter 
Quote:
Originally Posted by Andrea View Post
Thanks...

And how about midrange & treble transparency? Is it better than the XTRA? (keep in mind that I don't believe much myself in long burn-ins of amps/sources/etc.)
Well we can agree to disagree on this one. I have the blue XTRA that was at the same point as the black and I stopped using it for comparison reasons, and Andrea, there is a difference and it is not in my head.

The treble and midrange of the XTRA black is very nice. Highs are extended and mids are not in your face but smooth and natural. For the money this is a tremendous amp. I have the LD M+ and they are nothing at all alike. The XTRA has some real circuitry and about 20 times the parts. You can even change the battery because it plugs in but on the LD it is soldered into place. The bass on the XTRA is much stronger and integrated than on the LD. The XTRA could sell for much more. You need to let it burn in, oh sorry, get used to you and like you to give its all. :^)

The Micro Tube is separating the vocals and instruments more and not congesting as it ages and learns what to do. I can hear more separation with the Micro tube over the XTRA but I could easily live with the XTRA and not worry. I will have the Xin IV shortly and will give the XTRA a real run for the money on the comparison.
post #17 of 173
Thank you very much. The Little Dot Micro Tube sounds like another amp to have.


I believe that the XTRA can easily enough be further improved by replacing the (pretty good, nonetheless) OPA2134 with an AD8620 (quite sonically compatible with the HD650), an AD823 (great op-amp also, perfect for the Senns) or, if it goes well without DC offset (likely but not guaranteed), the fresh new LM4562 that seems to be a breakthrough in audio op-amps in a few people's words (one being head-fi's PinkFloyd).
post #18 of 173
Oh and regarding burn in we don't need to agree to disagree - I could also make a small exception in order to trust your hearing
post #19 of 173
Thread Starter 
Yes the LM4562 is what the Micro Tube has.

Around 50 hours now and the soundstage is realllly opening up. Almost spooky on some recordings. It is going way beyond my head and opening into a very nice soundfield. I did notice on mine that it does have the good Vishay/Dale resistors. I have liked these for years and I normally do not like metal film resistors. The parts in the amp are very good. You can roll opamps and even with a special board the buffers using the ha5002.

I wonder what this will sound like at 100 hours. oh I forgot about the burn-in issue. Caps form, chemical changes occur, the dialectric properties of the circuit board change due to curing and capacitance of the trace interactions with said board alter, inductance properties change, micro crystalization in conductive material alters the diode effect, or maybe nothing happens. :^)
post #20 of 173
Quote:
Originally Posted by jamato8 View Post
oh I forgot about the burn-in issue. Caps form, chemical changes occur, the dialectric properties of the circuit board change due to curing and capacitance of the trace interactions with said board alter, inductance properties change, micro crystalization in conductive material alters the diode effect, or maybe nothing happens. :^)
On this I most definitely agree. It's just that I wouldn't know how long it actually takes.
post #21 of 173
Thread Starter 
Yes, that is the unkown. Too many variables. I have had Black Gate caps take hundreds of hours to settle/form with the sound going through open and airy to dull and lackluster and poor bass as the electron flow was messed with.
post #22 of 173
Have you tried your porta-pros with this? They have similar sensitivity to the Grados, I think. I'd like to know whether or not this amp will sound good with my SR-225.
post #23 of 173
Thread Starter 
I will give that a go. I have an adapter with me so I can use the mini plug as the Micro Tube uses a standard plug, which is nice.

I have about 75 hours on it and it is opening up very, very nicely now. The details are coming through more clearly and the bass impact is well placed and does not muddy the sound.
post #24 of 173
Thread Starter 
About 80 hours and the bass is really kicking in. The soundstage has stepped back and is more realistic. The bass is solid and kicks a%$. The detail has increased and transient response is excellent. I am getting a little bit of microphonics in one tube, such is the life of tubes. Andrea tubes are hot and sometimes talk to you but you can always get another one.

The sound moves you with the music. A very involving soundstage at this point.
post #25 of 173
Thread Starter 
I am using the PortaPros with the amp and the sound is open and airy. I have noticed with the passing of time that the amp is developing a more open and dynamic character. It is driving my HD650's with ease and the sound is sweet and musical without a lush and over the top tube sound that can dominate some amps. At this point it reminds me of the good aspects of the vaccuum tube's ability to render music without the sterile effect of some solid-state devices. Reverb and decay are natural and add dimension to the musical enjoyment.
post #26 of 173
Thread Starter 
200 hours and this amp is becoming very airy and open. It is presenting a very natural soundstage. On Eric Clapton's "Unplugged", the feeling that you are at a live even is very present. There is body and weight to the music and voice and an organic realism. I find IC's are important and that the Pivot with a mini at one end and the RCA's at the other works very well. I am finding the amp quite neutral and dynamic with good control and authority when driving the HD650's. I am very happy to have purchased this amp. At 200 dollars it is a true bargain.
post #27 of 173
I'm glad to hear that it controls the HD650's well, but I wonder how it would do with K701's considering everyone says the AGK's are harder on an amp than Senn's.
post #28 of 173
Quote:
Originally Posted by Chops View Post
I'm glad to hear that it controls the HD650's well, but I wonder how it would do with K701's considering everyone says the AGK's are harder on an amp than Senn's.
It does it extremely well. My Micro Tube has about 72 hours of burn in and it is driving the K701 very well. The sound is indeed airy and the bass has a very nice presence w/o becoming bloated or too much. Very happy with this amp.
post #29 of 173
Quote:
Originally Posted by mrarroyo View Post
It does it extremely well. My Micro Tube has about 72 hours of burn in and it is driving the K701 very well. The sound is indeed airy and the bass has a very nice presence w/o becoming bloated or too much. Very happy with this amp.

Hmm... Very very interesting. That makes this little tube amp very temping for me. See, I have been figuring on either the MF XCAN V3, LD II++, or Darkvoice 336i. Eventhough it's $400 and I'd have to save for a while longer, I've been leaning towards the XCAN due to my limited desk space. However, I now wonder how this new Micro Tube would fair against the rest of them, especailly against the XCAN. The price is much better, that's for sure, and the size would be super-easy to work into my desk area. Any thoughts?

BTW, sorry OP. I didn't mean to hijack the thread or anything.
post #30 of 173
Thread Starter 
Yes, with the dual buf634 per channel you get a .5 watt output. That should leave plenty of headroom and you could always stack one of the 634's or both of them and get even more output power and slightly lower, though i doubt noticable, distortion. They run the 634 with no resistor in the high C mode which give the widest bandwidth. I haven't felt the 634 running with no resistor between pin 1 and 4 but it should get warm to hot with regard to thermal dynamics and I hope this is not a problem. Normally a 200 or 100 ohm resistor ties the two pins together for the high C mode.

I am listening to the M tube now with my OVC 25's, which are sorta like the Vibes and it sound very good with these IEM's. Solid bass and nice air.

I am anxious to try out some 6111 tubes. I have some waiting for me back in the states. The pinout is different but that is no big deal as I will solder them in the correct orientation in 8 pin sockets. The 6111 dates back to 1945 and has many US makers.
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