[phergus_25]

humm, well there goes my theory about it being the 02 tubes that are blowin up.

 

[Dept_of_Alchemy]

Quote:

Originally Posted by phergus_25 humm, well there goes my theory about it being the 02 tubes that are blowin up.

And to put the final nail in the coffin... one of my 01 tube started flashing as well.

How long does it take for replacement tubes to arrive?

 

[Dept_of_Alchemy]

Did everybody noticed an obvious improvement in sound quality when they used the LDII versus their sound card? I only noticed a slight improvement over my Creative SB2 when I connected the LDII+ to the headphone out on the SB2. I was also using a pair of PX-100...

DAC and HD650 are both being modded...

 

[nichifanlema]

Does this "Arcing" thing also happen to the Little Dot II?

or just Little Dot II+ ?

 

[izquierdaste]

I never had a problem with my ld2, nor did I read of this problem until the ld2+. THis is strange since they use the same power tubes. Maybe some mistake was made in the p2p wiring, although I have no basis for that statement. It just seems strange that so many people with the ld2+ are having problems with power tubes and that this problem didn't occur with ld2. By the way, I think the ld2 is a great amp, but overpowering for most current-production headphones. I wonder if anyone has compared the ld2 to ld2+ for easy to drive headphones.

 

[hYdrociTy]

Quote:

Originally Posted by Dept_of_Alchemy Did everybody noticed an obvious improvement in sound quality when they used the LDII versus their sound card? I only noticed a slight improvement over my Creative SB2 when I connected the LDII+ to the headphone out on the SB2. I was also using a pair of PX-100... DAC and HD650 are both being modded...

Soundstage is a definate improvement. It was the easiest thing to discern for me. It is even more apparent on smaller cans like ksc75 and maybe your px100 also.

 

[penguindude]

Quote:

Originally Posted by Dept_of_Alchemy Did everybody noticed an obvious improvement in sound quality when they used the LDII versus their sound card? I only noticed a slight improvement over my Creative SB2 when I connected the LDII+ to the headphone out on the SB2. I was also using a pair of PX-100... DAC and HD650 are both being modded...

Have you tried it on a pair of full-size headphones?

 

[m8o]

Quote:

Originally Posted by phergus_25 I would suggest getting them replaced if you saw ANY arching. I would hate to see exensive equiptment on the sourece end and output end get fryed.

I understand the caution. I feel I should share my experience on this topic however.

I -did- notice a flash a few times and a louder then usual pop in the headphones a few times on start-up early in the life of my LD II+. I wondered if I was a 'victim' too of what had been reported; especially the serious failure that had been reported that blew out those phones and other devices was causing an arch between the pads (yikes I say!). But as I observed the amp on subsequent restarts -- the 2nd one after I first observed a 'flash' being very, ahem, tentative

-- always after the amp had been off over night for 15 hours or more, the 'pop' quickly subsided and the 'flash' was soon not visible (no, my headphones are not blown or even damaged). I recall I may have seen it flash 2 or 3 times.

So I'm saying, it -did- go away. After not using the LD II+ for about 3 weeks recently for a few reasons (either was using the LD III+, or was home sick, or when I was in @ work the amp was @ home) , I've been dilligently observing the tubes on start-up this past week with the headphones on my head, and all I get now is the subtle and normal sound of the capacitors charging up; definitely no 'flash'.

So I think what we really need is a scientific response from the manufacturer of the Little Tube, if he is able, hopefully one that he gets from the tube manufacturer themselves, on what that flash is exactly. It may be the tip of a lead that was left too long in manufacturing and is close enough to an oppositly charged lead that it archs until it carbonizes to the point that is can't arch any more. ...maybe. I don't know.

But I do know that if the 'flash' isn't persistent past a hanful of startups, the tubes can get past that and operate perfectly. I do believe Sword Yang or David had said something similar ...Hey, how do you guys know that the tubes you are getting that don't experience a flash haven't gone through a few dozen on/off cycles being one that was a QA sample, and passed through any 'flashing' stage it might normally have? Just playing devil's advocate.

 

[golgi]

I wish mine had stopped doing it after the first few weeks. But I've had my LDII+ since they first came out which was a little over 3 months ago I think. It's always popped and had the blue flash in the power tubes on my LDII+.

Still, I have to say I do really like the sound quality of this amp. Now if I could just get rid of that blue flash and pop then I'd be set. The only reason being that I don't want any of my gear to get damaged from this. If this wouldn't harm any of the other gear that I have connected to it then I have no big issue with this.

 

[Dept_of_Alchemy]

Has anyone tried to use the pre-amp out and the headphone out at the same time? I'm curious to try hooking up a subwoofer to the pre-amp out on the LDII+ while listening to headphones... will this reduce the sound quality in the headphone out?

 

[m8o]

Quote:

Originally Posted by Dept_of_Alchemy Has anyone tried to use the pre-amp out and the headphone out at the same time? I'm curious to try hooking up a subwoofer to the pre-amp out on the LDII+ while listening to headphones... will this reduce the sound quality in the headphone out?

When you do it with the LD II+ , there's a slight (3dB-ish?) reduction in level in the headphones. It's almost as if the 'attack' seems subtly 'softer' to me too, but that might just be my head incorrectly interpretting the reduction in volume. When you do that with the LD III+, the headphone out is unaffected.

 

[sword_yang]

Hey guys, we've received a lot of questions regarding the 4P1S power tubes used in our Little Dot tube amplifiers in the past few weeks, most of which point us back here to the Head-Fi forums. We definitely recognize the issue and we have taken some steps to remedy the current tube situation.

First of all it's important to put this issue in perspective. As with almost all merchandise, whether it is tube amplifiers or a headphone, the customers who receive the "lemons" will always tend to be the most vocal, and thus may actually seem like the majority. In reality, the percentage of Little Dots shipped with faulty tubes is not large – not 25%, not 10%, and not even 5%. Out of the hundreds of Little Dots we've shipped, there have been less than 10 instances of customers reporting faulty tubes. Again ideally this number would be zero, but if we cannot guarantee a 0% defect rate, we can most assuredly guarantee prompt rectification of the problem and final customer satisfaction.

Secondly, all new Little Dot tube amplifiers produced in the past few weeks now have a suppression diode to isolate the vacuum tubes. If a tube is faulty, it will not adversely affect any other components within the amplifier or connected to it.

Lastly, all Little Dot tube amplifiers purchased through official channels from now until an indeterminate time in the future will ship with an extra set of 4P1S power tubes. This will ensure that on the off-chance that a power tube is bad, the customer immediately has a replacement on hand. For the majority of customers who do not have any issues, hey, free spares!

Again we apologize for the inconvenience to some of our customers, if you've experienced faulty tubes, please contact us and we will send out replacements immediately.

 

[Duc]

Is there anything we can do to install the updated diode into the older build. Or does the PCB differ?

 

[golgi]

Sword_yang, I have to commend on your effort to maintain good customer relations. Also I'd like to let you know that regardless of this issue, I've been very happy with the sound quality of my LDII+ and don't have any regrets about buying it. I'll continue to recommend it to others as it's a great value.

 

[DRSpeed85]

I agree. It definitely has fantastic value. A proper "beginners" tube amp.