[mrs1986]

  im sure it will be a fine DAC just be aware of the ground loop issue introducing noise into the signal since the LD has a transformer built into the chassis grounded to the wall which was fully present in my USB DAC or soundcard or anything out of my desktop. I have the LD with upgraded tubes and upgraded op amp. It pairs extremely well, tames the highs and gives texture to the sometimes unnatural decay and clarity that the 400i have at times. I dont think you will find alot of users here that have everything stock on the LD since the first thing they do is tube rolling and op amp rolling.  Your options for the ground loop noise which i can almost guarantee will be present as as follows:
 
Humx eliminator (expensive and may not work)
Cheap RCA ground loop isolators (Alters Sound)
3 prong to 2 prong cheater plug (dangerous)
 
or do what i did with an isolation transformer with a $20 transformer from digikey and some spare parts for the housing and plugs. That way you can ensure clean constant power to your LD and get rid of any noise that may be present.   

Wow, super fast response!
 
I'm sorry, but what is the ground loop issue? It will happen If I pair it with my AK Jr?? It won't happen if I use a desktop DAC?
 
I'm not an electronic guy, I just code so I have no idea how to do what you suggest me to do... :/

 

[CHxJC]

  Wow, super fast response!
 
I'm sorry, but what is the ground loop issue? It will happen If I pair it with my AK Jr?? It won't happen if I use a desktop DAC?
 
I'm not an electronic guy, I just code so I have no idea how to do what you suggest me to do... :/

If you're planning on just listening directly from those AK jr, and not using it as an USB DAC (connected to a PC) you'll be fine. The issue is the little dot 1+ seems to not like being paired with USB DACs with internal batteries (No problem with my ODAC, but creates a I suspect a ground loop effect with my FiiO Q1 creating a humming sound). Disabling charging worked for me, and for trivium911 it worked by building an isolation transformer. 
 
With that said, this doesn't mean that it'll happen to you. 
 
The ground loop affect is basically the third "ground" pin on the plug interfering with other electronics that share this ground. A cheater plug is the easiest solution (basically makes it so that the third pin doesn't plug into the wall). The down side that it is dangerous. (Although I would argue if you live in a humid country cheater plugs aren't "that" dangerous. My parents used cheater plugs on heaters, hair dryers for decades and nothing happened...yet.)
 
EDIT: Read your original post. To answer your question:
1. The AK jr has USB DAC support (according to product page) and could be used as a DAC. It should be way better than any budget DAC judging from its price.
 
2. For starters, leave the Opamp as it is and see if you want to upgrade it later down the road. The tube makes a way bigger difference to the sound. I definitely recommend upgrading the stock tubes, as they are pretty bad (especially the bass, absolutely no extension at all). I recommend reading this thread http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide, and start with a neutral-ish tube to begin with to get a taste how a good tube sounds like. After that, have fun finding the tube you like most! (Personal favourites are the Mullard M8161/CV4015). Keep in mind depending on the tube family, you might need to open up the case and plug in the 2 J1 jumper caps.

 

[mrs1986]

If you're planning on just listening directly from those AK jr, and not using it as an USB DAC (connected to a PC) you'll be fine. The issue is the little dot 1+ seems to not like being paired with USB DACs with internal batteries (No problem with my ODAC, but creates a I suspect a ground loop effect with my FiiO Q1 creating a humming sound). Disabling charging worked for me, and for trivium911 it worked by building an isolation transformer. 

With that said, this doesn't mean that it'll happen to you. 

The ground loop affect is basically the third "ground" pin on the plug interfering with other electronics that share this ground. A cheater plug is the easiest solution (basically makes it so that the third pin doesn't plug into the wall). The down side that it is dangerous. (Although I would argue if you live in a humid country cheater plugs aren't "that" dangerous. My parents used cheater plugs on heaters, hair dryers for decades and nothing happened...yet.)

EDIT: Read your original post. To answer your question:
1. The AK jr has USB DAC support (according to product page) and could be used as a DAC. It should be way better than any budget DAC judging from its price.

2. For starters, leave the Opamp as it is and see if you want to upgrade it later down the road. The tube makes a way bigger difference to the sound. I definitely recommend upgrading the stock tubes, as they are pretty bad (especially the bass, absolutely no extension at all). I recommend reading this thread http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide, and start with a neutral-ish tube to begin with to get a taste how a good tube sounds like. After that, have fun finding the tube you like most! (Personal favourites are the Mullard M8161/CV4015). Keep in mind depending on the tube family, you might need to open up the case and plug in the 2 J1 jumper caps.

I see, how I'm supposed to plug the jr to pc and to the LD?? I guess it will be the same as using it as a source?? As I would need to use the headphone/line out of it...

I'm not from US, tube rolling would get pretry expensive fast :/ Is there any pair of tubes that are pretty "universal" and good enough for everyone??

 

[CHxJC]

I see, how I'm supposed to plug the jr to pc and to the LD?? I guess it will be the same as using it as a source?? As I would need to use the headphone/line out of it...

I'm not from US, tube rolling would get pretry expensive fast :/ Is there any pair of tubes that are pretty "universal" and good enough for everyone??

It might be in your best interest to refer to the manual. I would guess connecting the USB port to the PC, and then switch some setting within the device. Since it only has 1 jack, I assume it will output from the headphone jack as usual. Simply use a 3.5mm to RCA line to connect the AK jr to the amps RCA inputs.
 
Tube rolling is expensive even if your are in the US 

. Generally the most recommended starters are the voshkod 6zh1p-ev, although I found them to be very EMI sensitive (They buzz from any electronic imaginable when coming near them, especially from my Apple pencil when I'm just trying to do my assignments). I bought mine from ebay shipped from Russia. They do take quite some time to ship though. Also make sure you buy a matched pair to ensure matched volume levels on both channels. Still, I highly recommend reading the tube rolling thread for impressions on different tubes as I don't know what type of sound signature you prefer.

 

[mrs1986]

It might be in your best interest to refer to the manual. I would guess connecting the USB port to the PC, and then switch some setting within the device. Since it only has 1 jack, I assume it will output from the headphone jack as usual. Simply use a 3.5mm to RCA line to connect the AK jr to the amps RCA inputs.

Tube rolling is expensive even if your are in the US  . Generally the most recommended starters are the voshkod 6zh1p-ev, although I found them to be very EMI sensitive (They buzz from any electronic imaginable when coming near them, especially from my Apple pencil when I'm just trying to do my assignments). I bought mine from ebay shipped from Russia. They do take quite some time to ship though. Also make sure you buy a matched pair to ensure matched volume levels on both channels. Still, I highly recommend reading the tube rolling thread for impressions on different tubes as I don't know what type of sound signature you prefer.

Thanks a lot for the advice!

I will give a look at the thread and see what I can get, probably something available on amazon (i can buy here from outside us and use a forwarder to my country).

Thanks again!!

 

[CHxJC]

Thanks a lot for the advice!

I will give a look at the thread and see what I can get, probably something available on amazon (i can buy here from outside us and use a forwarder to my country).

Thanks again!!

NP!
 
I wouldn't recommend Amazon, as they don't have much of a selection (mostly American brands). I do know that the JAN 5654W are available on Amazon for an acceptable price for a matched pair. I'd recommend finding a reputable tube seller for rare tubes, or wandering around ebay for more common NOS tubes. Many of them ship a tad bit slow, but are great value (especially the ones with lower price but free shipping). Just beware of scammers!

 

[trivium911]

Thanks a lot for the advice!

I will give a look at the thread and see what I can get, probably something available on amazon (i can buy here from outside us and use a forwarder to my country).

Thanks again!!

There is another option of buying one used, im in Canada and shipping on tubes and opamps can be expensive aswell. I bought my used on ebay who also happens to be a member here, i just put in his address and created the waybill on my fedex online account and emailed it over. If you do happen to get one used you get the benefit of it being broken in hopefully with a handful of tubes and upgraded op amps to get you started. Also the nice thing is the tubes are broken is aswell. You will need dual RCA male to 3.5mm male y cable to connect the LD to your device....preferably a sheilded cable assembly.

 

[mrs1986]

There is another option of buying one used, im in Canada and shipping on tubes and opamps can be expensive aswell. I bought my used on ebay who also happens to be a member here, i just put in his address and created the waybill on my fedex online account and emailed it over. If you do happen to get one used you get the benefit of it being broken in hopefully with a handful of tubes and upgraded op amps to get you started. Also the nice thing is the tubes are broken is aswell. You will need dual RCA male to 3.5mm male y cable to connect the LD to your device....preferably a sheilded cable assembly.

Getting one used is a really nice idea, I guess I will start to look around in the sale forum and see if I can get a used one in good shape and hopefully with some tubes!

 

[trivium911]

@jleewachter
was selling one, you might want to check with him. I almost bought from him but he took to long to reply lol and thought it was sold.

 

[ls13coco]

Anyone have issues with gain?

I almost immediately changed the stock tubes for the mullards, and later on as I turned it up I notice a constant hum that increased with volume. So, I then swapped out RCA cables, opened her up and put in a dual op-amp from my Creative X7 (using that as dac with Sparkos upgrades) and foud the gain switch was "on" according to the manual. Turned them off, tested and it got loud quick. Opened it up again, to switch back. Still gets very loud, and the hum starts at about 4 o'clock on both "gain" settings.

I'm assuming the hum either is because these tubes have about an hour at most on them, or possibly I'm just in high gain all the time??

Oh, and love the sound none the less! First tube experience and so glad I got the warm smooth mullards..

 

[trivium911]

Anyone have issues with gain?


I almost immediately changed the stock tubes for the mullards, and later on as I turned it up I notice a constant hum that increased with volume. So, I then swapped out RCA cables, opened her up and put in a dual op-amp from my Creative X7 (using that as dac with Sparkos upgrades) and foud the gain switch was "on" according to the manual. Turned them off, tested and it got loud quick. Opened it up again, to switch back. Still gets very loud, and the hum starts at about 4 o'clock on both "gain" settings.


I'm assuming the hum either is because these tubes have about an hour at most on them, or possibly I'm just in high gain all the time??


Oh, and love the sound none the less! First tube experience and so glad I got the warm smooth mullards..

What is your source?

 

[ls13coco]

What is your source?

Whoops, missed this.

The Creative X7 with 4x Sparkos op-amps is my source.
The hum/buzz seems to be getting better slowly, I notice I can continually turn the volume up higher without audio playing until I can start hearing it.

I am still confused about my gain though.. really wish after all this time that LD did a slight revision, and put a gain switch on the outside.

 

[trivium911]

Whoops, missed this.


The Creative X7 with 4x Sparkos op-amps is my source.

The hum/buzz seems to be getting better slowly, I notice I can continually turn the volume up higher without audio playing until I can start hearing it.


I am still confused about my gain though.. really wish after all this time that LD did a slight revision, and put a gain switch on the outside.

Unplug the rcas from the liddle dot but leaving the power on. If it goes away you have a ground loop with your creative x7

 

[ls13coco]

Unplug the rcas from the liddle dot but leaving the power on. If it goes away you have a ground loop with your creative x7

No RCA, volume can be maxed with no buzz. Thanks! Now to figure how to fix this.. The devices are several feet apart so I guess it won't be that easy.

 

[trivium911]

No RCA, volume can be maxed with no buzz. Thanks! Now to figure how to fix this.. The devices are several feet apart so I guess it won't be that easy.

You can try a few things such as a sheilded power cable for your computer and a sheilded usb cable with the round magnet on the end that plugs into the creative x7 dac. If you can safely eliminate the need for grounding the little dot chassis than it will eliminate the problem, they make a device called a humx which is supposed to get rid of ground loops but it is pretty expensive. Do not use the cheater adapters which eliminate the ground to the wall as they are dangerous. You could also go the route i did and build a minature isolation transformer, which cost me around $20 cad and some spare parts i had lying around at work, you have to be comfortable working with 120v though and if you hook it up qrong you can get elctrocuted so something to be aware of. You can also purchase and isolation transformer but they are expensive and i was not able to find one that was small and compact which is why i built my own.

I was reading before i built my isolation transformer how a capacitor and a resistor can be soldering between the ground plug from the little dot and the chassis, so instead of ground going straight to the chassis it goes through the resitor and the capacitor first. I am not sure how safe that is and the guy who posted it never reaponded to my PM ( the post was very old).

Laat but not least tou can buy inline ground loop isolators that just folter the noise out through the RCA connections. After spending alot of money on my amp, source and headphone i did not want to plug some cheap filter ground loop isolator in and potentially ruin the sound. I cannot say whether or not a difference can be noticed but i prefer to just have peace of mind and have nothing alter or filter the sound.