[Lil' Knight]

You mean the volmeter? I think it depends on the tubes. When I changed the stock 6080 to TungSol 5998, the volmetter decreased a lot. And, I'm plugging the MKVI to my Belkin power splitter. Maybe that's the reason.

 

[pgruebele]

That's interesting. Changing to 6H13S power tubes made no change in the bias. According to David the VI auto-biases, so the meter should always read around 60 no matter what output tubes are used...

I believe that if your bias is too low, your amp will operate in class A/B instead of pure class A, which will cause higher distortion on larger signals. On the other hand, this will cause your tubes to generate considerably less heat.

At any rate, David told me he would send me updates to the manual which explain how to adjust the VI's bias. When I hear back from him I will post the info here... This might be worth looking into.

 

[Lil' Knight]

That's great. I may ask him about this too.

 

[pgruebele]

On another note, you switched from using the DacMagic to Dac1, right? Can you summarize the change in sound you got from this upgrade? Is it worth the cost? Which Dac1 model do you have?

Thanks

 

[Lil' Knight]

Yes, I upgraded from the DacMagic to DAC1. Mine is USB version.
The biggest change was in details and soundstage. The details of the DAC1 are just awesome, I can hear more sound that I couldn't hear from the DM. The DAC1 is more forward and bright while the DM is a little bit laid-back and warm. IMO, it's a worthy upgrade.

 

[Maxvla]

Got a 6080 tube that's developed a static problem in the last 2 days. I've isolated it as the cause with help from David. By the way, David does a great job with his service. We've exchanged half a dozen emails since yesterday trying to track this down.

First question is how long should tubes last? 2 weeks is all the time I have on these and I already have one dying. I was under the impression these lasted for much longer.

Second question is since I have to replace them I might as well at least try something different as long as it doesn't cost too much. I've isolated that it is one of the 2 6080s I've moved from left to right. If I stay with 6080s do I just need the pair replaced or should I replace all 4? If I don't stay with the 6080s what would you guys suggest? I see the 6080s on eBay for around $5-10 each. If I'm buying 4 I'd rather not exceed $20 per tube.

 

[Maxvla]

Here's a pic of the offending 6080, not the greatest quality, sorry.

Does that look like rust on the edges there? Or is that some kind of gap filler?

 

[Maxvla]

Well I didn't want to wait much longer so I ordered a quad of 6AS7G to give them a try.

 

[auee]

Sorry to hear of your tube troubles. Keep us informed of the reliability of the amp and how the new tubes sound and hold up.

 

[cafe zeenuts]

Cleans those tube pins with deoxit.

 

[Maxvla]

Quote:

Originally Posted by cafe zeenuts /img/forum/go_quote.gif Cleans those tube pins with deoxit.

See the red tint? That's deoxit.

 

[cafe zeenuts]

Oh I c, well if the deoxit didn't work then it's a bad tube. Nothing you can do about it except get a replacement!

 

[cafe zeenuts]

According to the LD there is a warranty on tubes that are DOA or fail within 3 months of purchasing the amp. Did David send you some replacements?

I just had a close look of your pics and it seems that the pins and base is still damp with deoxit, you might want to dry them more before putting it back into the amp.


Cheers

 

[El_Doug]

too bad I just told my tung-sol's, i woulda offered them to you as a fellow head-fi'er

in the end, I felt the driver tube upgrade to ecc35's made a world of difference. however, I couldnt justify the $150+ for the 5998's - the difference was really extremely small

 

[Maxvla]

Quote:

Originally Posted by cafe zeenuts /img/forum/go_quote.gif According to the LD there is a warranty on tubes that are DOA or fail within 3 months of purchasing the amp. Did David send you some replacements? I just had a close look of your pics and it seems that the pins and base is still damp with deoxit, you might want to dry them more before putting it back into the amp. Cheers

He did offer to replace them with only a shipping charge, but for such inexpensive items the shipping charge is pretty hefty from China. I bought a quad of 6AS7Gs for about $35 shipped from here in the states that will arrive sooner and it's different so I can try this mysterious tube rolling you guys talk about.

When I first got the amp I used deoxit on the pins before installation because it said so in the manual, but in the interest of trying 'everything' I repeated it. The pins were a little moist but nothing dripping, nothing would have happened to damage the amp.

If I don't like these new tubes I'll pay for a new quad + 1 from David. Would be good to have a full spare set. I'll have to think about the driver tubes and what to get as backups for those. I'll reread this thread and see what's affordable as well as good sound for driver tubes, but if you have any quick suggestions that works too.