Review and Measurements of Little Dot MK III Tube Headphone Amplifier

[jdjung]

Oh one more point. I have my Qudelix 5K charging full time while it's plugged into the Little Dot Mk3 and no noise, no hum, nothing, just clean music. Love this guy.

 

[DonR]

It is extremely susceptible to ground loops but once that is conquered it is very quiet.

 

[jsrtheta]

Oh one more point. I have my Qudelix 5K charging full time while it's plugged into the Little Dot Mk3 and no noise, no hum, nothing, just clean music. Love this guy.

I have the Mk.ii, and I've never had any noise issues at all.

 

[milosz]

I've never had noise issues on my Mk iii. I haven't listened using the Little Dot for quite a while ( I have too many headphone amps...) I'll have to dust it off, I've acquired a few headphones that I've never tried with the Little Dot.

I have done a little tube - rolling some time ago, which was kind of fun.

 

[jdjung]

I've never had noise issues on my Mk iii. I haven't listened using the Little Dot for quite a while ( I have too many headphone amps...) I'll have to dust it off, I've acquired a few headphones that I've never tried with the Little Dot.

I have done a little tube - rolling some time ago, which was kind of fun.

I did some tube rolling back in the day and it was a lot of fun. I'm wondering if there is a cool tube rack display case you can buy which you can keep next to your tube amp to easily swap out tubes.

 

[milosz]

I did some tube rolling back in the day and it was a lot of fun. I'm wondering if there is a cool tube rack display case you can buy which you can keep next to your tube amp to easily swap out tubes.

Interesting idea. Sounds like something you might see on Etsy or sold on US Audio Mart. Several versions could be possible for different size tubes headphone amp / preamp / power amp sizes.

 

[jdjung]

You know, I've had this amp for about ten years and bought it for $110 on Craigslist and it was the best investment I've made as a proclaimed audiophile. The person sold it to me because he kept getting noise from the RCA no matter what he was plugging it into. It was a ground loop noise. I currently have it setup with NO NOISE from a Qudelix 5k and stream my phone or computer directly by LDAC. I also have it hooked up this way to my Drop THX 789 as a preamp using the RCA's out the back. Given that noise on these tube amps can be different for different volume levels, this gives me more control to find the sweet spot by having the 789 raise the level of the tube amp. I have the balanced inputs on my 789 attached to my Antelope Audio Zen Q if I don't want to use the Little Dot Mk 3 as a tube preamp.

PSA - I saw some people were stating that the RCA inputs on the Drop THX 789 were prone to stop working if the levels were to high. I have noticed a pop sound even when I turn my Little Dot Mk 3 amp on before my THX AA 789. Just in case, I've put a mixer (Mackie 402VLZ4) between the Little Dot Mk 3 and the Drop THX 789 and the pop sound has disappeared when I turn on my THX 789. So far very happy with this setup as it can also be used to adjust any channel imbalance on the Little Dot Mk 3 and see no difference in sound quality.

 

[dolph99]

PSA - I saw some people were stating that the RCA inputs on the Drop THX 789 were prone to stop working if the levels were to high. I have noticed a pop sound even when I turn my Little Dot Mk 3 amp on before my THX AA 789. Just in case, I've put a mixer (Mackie 402VLZ4) between the Little Dot Mk 3 and the Drop THX 789 and the pop sound has disappeared when I turn on my THX 789. So far very happy with this setup as it can also be used to adjust any channel imbalance on the Little Dot Mk 3 and see no difference in sound quality.

I may be wrong on this, but wouldn't the feed forward "correcting" amplification circuit in a thx amp cancel any distoration introduced by a tube preamp? In which case, you don't add anything from the tube preamp. It may be adding gain or not. It may be doing nothing at all.

I have searched and searched but can't find a satisfactory answer to this. I did find a very long thread elsewhere in which various different tube preamps were tried by lots of people and most of them noticed no difference in sound.

This makes sense if either the most difference is to be found in the tube output stage, which you can only get with a proper tube amp, or if any effects of the tube preamp are being nullified.

 

[jsrtheta]

PSA - I saw some people were stating that the RCA inputs on the Drop THX 789 were prone to stop working if the levels were to high. I have noticed a pop sound even when I turn my Little Dot Mk 3 amp on before my THX AA 789. Just in case, I've put a mixer (Mackie 402VLZ4) between the Little Dot Mk 3 and the Drop THX 789 and the pop sound has disappeared when I turn on my THX 789. So far very happy with this setup as it can also be used to adjust any channel imbalance on the Little Dot Mk 3 and see no difference in sound quality.

In my quite amateur opinion, that sounds like a lot of extraneous crap in the signal path.

 

[DonR]

I may be wrong on this, but wouldn't the feed forward "correcting" amplification circuit in a thx amp cancel any distoration introduced by a tube preamp? In which case, you don't add anything from the tube preamp. It may be adding gain or not. It may be doing nothing at all.

I have searched and searched but can't find a satisfactory answer to this. I did find a very long thread elsewhere in which various different tube preamps were tried by lots of people and most of them noticed no difference in sound.

This makes sense if either the most difference is to be found in the tube output stage, which you can only get with a proper tube amp, or if any effects of the tube preamp are being nullified.

No. The THX amp will see the output of the tube amp as a "source" signal. Any error correction, whether via feed-forward or back, will simply correct the error introduced by the THX amp itself or due to the loading of the source output or the headphones.

 

[Veri]

I may be wrong on this, but wouldn't the feed forward "correcting" amplification circuit in a thx amp cancel any distoration introduced by a tube preamp?

No. It amplifies/boosts for example a -90dB signal with (just about) no further pollution: the amp itself is transparent so won't "add" more distortion but it cannot make something unclean clean.