Review of the Little-Dot MKII Tube Headphone Amp/Pre-Amp
Feb 21, 2017 at 11:08 AM Post #526 of 658
I have not been using my v2 MKII for long time, something that will change soon since i plan to put it back in the system.
 
I have already changed 2 small WIMA caps with Clarity Cap ESA but i would like to replace the rest of the caps as well. The problem is the space is very limited so i would appreciate suggestions.

 
I also have a question for the preamp tubes. I use CV4010 right now but i wonder if anyone has tried C3G tubes with adapter.
 
Mar 15, 2017 at 4:12 AM Post #527 of 658
On low gain, does the little dot mk2 match well with let's say a grado sr60-325 headphone or is the noise to much? I'm looking in to get a entry level tube amp but im curious about the noise situation since most of my headphones are quite easy to drive. 
 
Mar 21, 2017 at 3:39 PM Post #528 of 658
Hello,
 
Well I've the same type of questions :wink:
What about mkII and low impedance headphones ? is it ok ? or the basse trends to loose some control ?
 
By the way, what's your opinion with thoses headphones :
- fostex th-X00 (25ohms)
- HE-500
- shure srh1540 (46Ohms)
- DT 1770 (250Ohms)
 
Thx in adavance
 
Regards,
 
Mar 23, 2017 at 4:16 PM Post #529 of 658
Hello guys, I am using a LD MK II (6N6P power tubes, Mullard M8100 driver tubes) for vinyl playback. I have a Project Debut Carbon DC with an Ortofon 2M Red cartridge and a Schiit Mani phono preamp. My cans are Audio-Technica ATH-M50x. I am missing the bass a bit in this setup and I wonder how I could fix it. When I hook the LD to my laptop and DAC it sounds good to me so I would rule out that I don't like the MK II's sound signature. However I have the impression that it is a little restricted because I have the volume at about 25% since the output of the preamp is quite loud even on the lowest gain settings. Is it possible that it would sound better (bass becomes more audible) if I could turn it up louder? Would that entail that I would need headphones with a higher impedance? Or should I maybe go for a different phono stage? 

I know this is all a little bit confusing but right now there are many questions in my head and I am trying to figure out how I could improve this situation.
 
Thanks very much in advance for your help guys!
 
Mar 23, 2017 at 7:08 PM Post #530 of 658
  Hello guys, I am using a LD MK II (6N6P power tubes, Mullard M8100 driver tubes) for vinyl playback. I have a Project Debut Carbon DC with an Ortofon 2M Red cartridge and a Schiit Mani phono preamp. My cans are Audio-Technica ATH-M50x. I am missing the bass a bit in this setup and I wonder how I could fix it. When I hook the LD to my laptop and DAC it sounds good to me so I would rule out that I don't like the MK II's sound signature. However I have the impression that it is a little restricted because I have the volume at about 25% since the output of the preamp is quite loud even on the lowest gain settings. Is it possible that it would sound better (bass becomes more audible) if I could turn it up louder? Would that entail that I would need headphones with a higher impedance? Or should I maybe go for a different phono stage? 

I know this is all a little bit confusing but right now there are many questions in my head and I am trying to figure out how I could improve this situation.
 
Thanks very much in advance for your help guys!

In my opinion, you really shouldn't pair a 38ohm M50x with OTL tube amp.
Suggestion from me:
A) Pair your headphone with solid state amp (or hybrid tube amp) if you do like the sound signature of M50x
B) Acquire higher impedance headphone. If you like bass and closed back, DT770Pro 250ohm might worth a try.
 
Edited: If you haven't already, LD MKII also have 4 gain from 3x~10x. Dip switches located inside the bottom cover.
Edited2: M50x don't really need an amp btw.
 
Mar 24, 2017 at 4:42 AM Post #531 of 658
Hello,
 
Well I'm reserching for my self an all aroud tube amp.
 
The Valhalla 2 is good with low impedance headphone : low output impedance because OTL with counter reaction.
But missing a little bit of power for HE 500.
 
Regards,
 
Nov 29, 2017 at 2:30 PM Post #532 of 658
I'd always been a solid state amp guy. I played around with a XDuoo TA-02 a while back, and while it had 2 EF95 family tubes, it still relied on solid state circuitry for power amplification. It sounded nice, but now resides on my desk at work. I also built a nice buffer based on the X10-D and enjoy it quite a bit with my Krell KSA5 Klone. I finally got a full tube amp when I joined the Little Dot MkII drop from Massdrop last month. I had ordered a selection of different tubes off of eBay while waiting for shipment, and got the amp and tubes all at once. The first listen with the stock Chinese tubes, was ok. The bottom end was somewhat muddy, the mids were acceptable, and the highs were somewhat harsh. I didn't give it a chance to burn in. I swapped in a pair of Novosibirsk 6N6P marked 8th week of 1973 and played around with some EF95 tubes. The sound was nice, especially with the Soviet tubes (more below). I opened up the amp with a plan to make a switch for the EF92/95 jumpers and lo and behold, the horrors!



The board was marked version 3. The build quality was dodgy at best. There was flux residue all over the place and while the soldering was solid, it was messy. The WIMA input coupling caps were melted at the bases. They were marked 3.3uF, and being tiny, were likely polyester. The other film caps were nasty generic globs whacked in willy-nilly. The film resistors were marked 1%, and when I measured them later after I cut them out, they were 1%, but barely. The big 5W resistors were 10% jobs. The LED was mounted too low and did not fit into the hole in the front panel. Finally, the bridge rectifier was some yucky no-name job. On the plus side, the electrolytic caps (UCC's, Nichicon's, and Rubycon's) were quite nice. The pot looked chintzy, but it's an Alps and actually measured well and sounded smooth.

An order was placed with Mouser, and after the package arrived, I got busy with the snippers and desoldering iron.



That's some Shenzhen market special!

After some work, much better!



The film resistors are Vishay RN55 (matched to 0.1% between left and right channels for the signal resistors) and CFP series. Yes, I even replaced the resistor to the LED. It was $0.10 so why not? The large 5W resistors are 1% and also Vishay's, but wirewound (don't care about inductance there). The film caps are WIMA 5% polypropylene. The large coupling caps are Kemet 3.3uF polypropylene. I have a pair of them in my Lehmann BCL clone and they sound very nice. There's a proper Vishay bridge rectifier, a Fairchild diode (again, also $0.10), a properly aligned LED, and a DPDT switch for the jumpers. The connecting wires were also switched out. I did not modify the circuit because I wanted to know what this little guy is truly capable of with good components.

The first set of driver tubes were a pair of Voshkod 6ZH1P-EV marked 11th week of 1981. Before the innards swap, they sounded nice. Good bass response and punch. Nice midrange, especially with female vocals, and clear highs. After the new guts, everything holds, but better. The bass extends down deep, but is controlled, tight and well defined. I wonder if the original WIMA's were actually 3.3uF. They were probably of a lower value so that the bass roll-off frequency was higher. The midrange is now front and center. Male and female vocals are lush and full. Mark Knopfler's Strat sounds so sweet. The highs are bright without being fatiguing. High-hats and cymbals are crystal clear with a smooth natural decay. The soundstage is astounding, giving my solid state amps a run for their money. There was a thin veil before, and now it's gone. Needless to say, I haven't got around to the other tubes.

The Little Dot will not replace my solid state amps, as when one gets down to the nitty-gritty, the solid states are technically superior. But boy, is the Little Dot fun, and I am looking forward to playing with the other tubes in my collection.


Is there a guide anywhere on how to do this? I just got one of these and would like to try it, but am not an expert. I'm handy with a soldering iron, and and have put together kits before, but I just want to make sure I'm getting the right parts and replacing them correctly.

Thanks!
 
Jun 18, 2018 at 2:38 AM Post #534 of 658
Would I be able too use this with IMR R1 IEMs(32 ohm's) and would it be an upgrade too the SMSL Idea dac/amp? And if so, would I be able too connect the Idea 3.5 out too the Little Dot rca inputs for dac responsiblity?
Thank you
 
Sep 23, 2018 at 10:39 AM Post #535 of 658
I have the Little Dot Mk. II+ iteration of this amp and replaced the stock tubes with Russian Voskod ( sp ) tubes.
I changed the settings on the switches inside to on for both 1 and 2 for low impedance phones at Gain 3 .
I use 32 ohm phones until I save enough money to get some 250 ohm Beyers .
" people say online " this type of amp works better with higher impedance phones .
To avoid damaging my headphones with the LD's voltage spikes at startup as shown on the Youtube video mentioned in an earlier post of this topic.... can I just plug a raw 8 ohm speaker hooked to a 1/4 in. jack in to the headphone output to present a load and protect the amp for startup ?
 
Nov 7, 2018 at 11:22 AM Post #536 of 658
How do these pair with stock HD-800's? I just bought them and don't really have an amp for them. Thanks!

The little dot 2 is a pretty nice amp paired with the HD 800. I have not listened to a TOTL tube amp mind you. But, I enjoy it over my monoblocks when I want a smoother and laid back presentation. It "warms" up the sound a tad and brings in the soundstage a smidge.
It is a nice change from the more analytical sound the HD 800 are known for. Sure they are still HD 800 "sounding" (very very good IMHO) but it adds a change in sound compared to my other amps that I use and does not disappoint. Makes my fun, "non audipphile" tracks very enjoyable.
I did upgrade the tubes (Voshkod 6ZH1P-EV) which make a difference in sound compared to the stock tubes, adds air between the instruments and provides very nice detail and sound.

You may have already settled on an amp by know but just thought I'd respond if anyone is on the same boat.
 
Nov 7, 2018 at 5:50 PM Post #538 of 658
Is it ok to use ATH R70X with MK II in High Gain mode(sw1,sw2_off)?

I don't see why not...I haven't had any problems with powering the hd800 or hd650 on the Little Dot's default mode.
But if there are benefits, SQ-wise, to up'ing the gain then that would be great. But default might be all you need.
If it comes down to it, you could try it and if it is hissing or causing noise then just flip it back down.
 
Nov 7, 2018 at 6:26 PM Post #539 of 658
I don't see why not...I haven't had any problems with powering the hd800 or hd650 on the Little Dot's default mode.
But if there are benefits, SQ-wise, to up'ing the gain then that would be great. But default might be all you need.
If it comes down to it, you could try it and if it is hissing or causing noise then just flip it back down.

Tried the the Highest Gain mode(sw1,sw2_off) but I get buzzing noise when I increase the volume. Now I went back to 7 Medium Gain Mode(sw1_on,sw2_off).

Is ground loop causing the noise when the amp is in high gain mode?
 
Nov 7, 2018 at 10:40 PM Post #540 of 658
Tried the the Highest Gain mode(sw1,sw2_off) but I get buzzing noise when I increase the volume. Now I went back to 7 Medium Gain Mode(sw1_on,sw2_off).

Is ground loop causing the noise when the amp is in high gain mode?

Very much could be, I think the sensitivity of the headphone might have something to do with it too.
 

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