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Little Dot Mk. III GTI........

post #1 of 8
6/19/11 at 4:08am
Thread Starter 

Having recently acquired an LD Mk.III, I am extremely impressed by the sound quality available for the outlay (through HD600s). However, I am a little dissatisfied with a few minor quality issues. The microphonic driver tubes are due to be replaced by NOS mil-spec Mullards any day now. That leaves the volume control, which not only feels cheap, but fails to mute the left channel entirely when set to "0". Does anyone know if an ALPS blue will fit (I want to keep the casework stock). If so, what value should I order? I want to have all the parts here before I open her up.....

Incidentally, is it worth replacing the coupling caps with Jensen PIOs, will they fit physically, and what values should I order?

 

Thanks in advance!

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post #2 of 8
6/19/11 at 7:04am

The Little Dot Mk3 already comes with an ALPS-16 potentiometer. The mk4 has the ALPS-27 which you may be able to exchange. I have the Mk2 which uses the 100k plain standard potentiometer mounted on the circuit board. I believe that the Mk3 has the potentiometer mounted on the front panel and attached to the circuit board by small wires. I can not confirm the exact value of the potentiometer that the Mk3 uses. 


Edited by john57 - 6/19/11 at 7:11am
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post #3 of 8
6/19/11 at 9:24am

as my MK III should be at home within a week, i will watch this with great interest as it will come with stock chinese tubes.

which tubes do you advise for it?

is there something like overview, which tubes fit MK III and which sound characteristics do they have?

As i am total new to the tube stuff.

Also, can someone explain to me  how logically OTL design works? I mean, how come that with high impedance headphones power output is increasing.

Like 200mW at 250 Ohms headphones, but 300 mW at 600 Ohm Headphones.

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post #4 of 8
6/19/11 at 9:35am
Thread Starter 

I've ordered NOS Mullard CV4010s (UK military spec, late 1970s). These should be more robust and manufactured to tighter tolerances than the stock drivers. The sound is, apparently (they haven't arrived yet) slightly "warm" but detailed and controlled.

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post #5 of 8
6/19/11 at 12:56pm

For Little Dot Mk3 tube rolling, you can go to the thread here:

http://www.head-fi.org/forum/thread/276757/little-dot-mkiii-tube-rolling 

 

OTL means no Output Transformer(less) for the tubes. Tubes operate with higher voltages and impedance's but lower current signal than solid state which makes tubes more suitable to drive higher impedance devices.

 

http://www.audiodesignguide.com/otl/otl.html 


Edited by john57 - 6/19/11 at 1:35pm
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post #6 of 8
6/19/11 at 1:45pm

i checked that thread but going through 160 pages is overkill.

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post #7 of 8
6/19/11 at 2:07pm

What I normally do with any thread that long is to read the first 5 pages and the last 5 pages.  I did allot of tube rolling with my Little Dot 1+ and the op-amp rolling as well. I just received my Little Dot mk2 similar to the mk3 in tubes. I send about 15 minutes reading that thread on the Mk3 to get a better idea on what tubes I could get with my mk2. For me I desided on the CV4010 and the super tube 6H30PI but I am no hurry to try them. I just wanted to enjoy the magic of the stock tubes for a bit longer. I also took the advise on post #14 of 2390  of the mk3 tube rolling thread. Take care!


Edited by john57 - 6/19/11 at 2:12pm
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post #8 of 8
6/19/11 at 11:41pm

nice advise :-)

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