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LD Micro Tube, ah tubes at last. . Buff634 bypassed

post #1 of 173
Thread Starter 
It finally arrived today. Nice looking and the sweet glow of tubes. Soooo smooth and warm. No real listening impressions as of yet since it has only been plugged in for 1/2 hour.

update: 5 14 07

I bypassed the LM4562 by using jumpers from pin one to pin three and pin 5 to pin 7. This eleminates an opamp in the signal path and using the tube as an SRPP to dual 634 buffers in high c configuration. The sound is organic, more flowing and to my ear has more of the qualities of a tube design that is fairly well implemented.

Update 5 19 07

I put the 4562 back in and bypassed the buffers. You bypass from pin 3 to pin 6 on the buffer. The buffers on one side are for both channels so you only have to do this on one side of the amp.

The sound is different. The bass is not as strong or solid as I would like but very interesting. The stage is huge and there is great separation of everything. It is an interesting listen. I will have to give it more time. The detail is greater and the micro and macro dynamics are pretty good but again I am not sure at this point about the bass. I am using my HD650's.

5 07

The buffers are back in. The amp needs these to drive with authority. The power supply needs to be left on all the time for the amp to sound full. I find that a couple of days is best before the sound is at its best so I never turn it off. The amp sounds best after it has been on for a half an hour or so.

For the asking price this is a nice little amp that gives a good performance. I do think other things could be done with the tube in the way it is used but I don't have the time to mod.
post #2 of 173









na, just kidding
post your impressions as they come
post #3 of 173
Thread Starter 
Funny guy! that is what I got on my review of the Woo3.

The sound is already changing.
post #4 of 173
More eagerness for impressions here
post #5 of 173
Thread Starter 
Listening to Vivaldi's Opus 9 is sweet. It is hard, in my opinion, to get the silky sweet sound of good violins, cellos and organ with anything but tubes. Oh, it can be done but tubes, when done right, just have it. The bass is firming up already with that nice control that you feel like a taut string being plucked. The sound is reminding me of my all tube system in storage. There is a certain quality that elludes other amplifying devices.

The power supply gets mildy warm and the amp about the same. The amplifier is light and the power supply though small is were the weight is, as to be expected with the transformer encased in said ps. Both the ps and amp are well ventilated. It appears that unless something crops up, they did their homework.
post #6 of 173
Evil question: with the HD650, do you feel it's better on all accounts than the XTRA ?
post #7 of 173
Thread Starter 
I can't say right now as I have no idea where the Micro Tube will end up. The XTRA is really a nice little amp and performs way past its price and what I ever thought it would. I need many more hours on the Micro Tube. I did notice that there appears to be blocking caps on the input to the tubes and with most all modern devices having little to know DC offset, I would prefer these out of the signal path. I know that I eliminate these from everthing I own if there. The Woo 3 came with them and I got them out of there real fast. Back to your equestion the XTRA does very well with the 650's.
post #8 of 173
The XTRA also has those DC blocking caps (Wima again). Thanks for answering, anyway.
post #9 of 173
Thread Starter 
I was wondering what those were doing. I have never taken the board and really looked it over and it is so small I need my magnifier with the light that I use (table model) but it is in storage in the states. Well I am not going to bother with the caps on the XTRA, I don't think. Although I have two and I could compare the sound. I probably can't hear the difference and frankly I want to listen to music and not A B all day. Huumm, blocking caps, what to do. . .
post #10 of 173
Quote:
Originally Posted by jamato8 View Post
I was wondering what those were doing. I have never taken the board and really looked it over and it is so small I need my magnifier with the light that I use (table model) but it is in storage in the states. Well I am not going to bother with the caps on the XTRA, I don't think. Although I have two and I could compare the sound. I probably can't hear the difference and frankly I want to listen to music and not A B all day. Huumm, blocking caps, what to do. . .

Hi John - If the blocking caps are in series with the input sockets then they are a precaution in valve gear to save the input device (iPod, CD whatever) in case the grid of the input stage valve develops an internal short to another high voltage electrode within the valve (usually the screen grid).
post #11 of 173
Thread Starter 
Quote:
Originally Posted by jirams View Post
Hi John - If the blocking caps are in series with the input sockets then they are a precaution in valve gear to save the input device (iPod, CD whatever) in case the grid of the input stage valve develops an internal short to another high voltage electrode within the valve (usually the screen grid).
Thank you for your comment. I never thought about it in reverse. I can't believe that having worked with tubes all this time I hadn't reflected on that but I must add that some tube manufactures I know fairly well do not use them because they do not feel there is a problem and prefer them out of the circuit. I know Cary Audio, who produces a large number of components have not used them for a very long time. Having said this I understand what you are saying.
post #12 of 173
Sweet looking little amp! I saw the claiming that they sound better than LD2++ on little-tube.com, any confirmation on that?
post #13 of 173
Thread Starter 
I have never heard any of the other tube offering from LD and I doubt that anyone else has received one of these at this time but who knows.

I can say that as it breaks in the sound is pretty fine. Last night it was getting a little closed in and lacked transparency but today, after having it on during the night and running through it, the sound is opening back up. It is going through changes so I am waiting for it to settle in but I think for the money it has no rivals.
post #14 of 173
Thread Starter 
Approaching 45 hours, not very much time but I am hearing changes. There is more focus and complex music is portrayed with aplomb. Voices can quite easily be discerned from surrounding instruments. The bass has taken on more authority and is going deeper without loosing control. I have never had a hybrid tube/solid state amp before as I prefer one or the other or to be honest, I am a tube guy. I think that 100 to 200 hours will give better impressions. I am comparing this to the XRTA X-1, which is an excellent little portable at any price but it appears the Micro Tube is pulling away. I would be happy though with the XTRA, it is that good. On bass the Micro Tube shakes most of the body, the XTRA, the upper part of the body.
post #15 of 173
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.)
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