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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 33

post #481 of 7565

maybe some corrosion in the tube socket itself?

post #482 of 7565
Quote:
Originally Posted by dxanex View Post

Since we are on the topic of tube hum, does anyone know why my RCA 5 Stars would be dead silent in my MKIII, but have a low frequency hum when in my Darkvoice 3322? Other tubes I've tried also will have a very loud hum (to the point I can't use them) in the DV that is inaudible in the MKIII. I've read some amps are self biasing so matching tubes isnt as important, but I believe the DV3322 is self-biasing...(correct me if I'm wrong)


how does one clean a tube socket? Would compressed air do the trick or is it more involved?

post #483 of 7565

I would try a super thin pipe cleaner with some deoxit spray and give it a few hours to dry upside down when you're done.

post #484 of 7565
Quote:
Originally Posted by dxanex View Post


how does one clean a tube socket? Would compressed air do the trick or is it more involved?

Maybe just take a bad tube put the stuff on it put it in ,take it out repeat that severall times it would be hard to find a better pin size to get in there imo.

post #485 of 7565

Just found a great combo, which I never tried before: CV 4015 (EF92) driver with 6N6P-IR power tubes. The IRs mild, warm, detailed and bassy sound complements the detailed and bright CV4015 very well. Together they sound neutral, natural, very detailed and very balanced. Wow, didn't quite expect that.


Edited by Acapella11 - 11/17/12 at 7:42am
post #486 of 7565

What sounds better to you - 6AJ5 and 6N6P or CV4015 and 6N6P-IR?

 

(For the 6N6P I use 70's gold grid tubes)
 

post #487 of 7565
Quote:
Originally Posted by MIKELAP View Post

Maybe just take a bad tube put the stuff on it put it in ,take it out repeat that severall times it would be hard to find a better pin size to get in there imo.


I just ordered a tube of Deoxit, so I'll give it a shot. I noticed the hum fluctuates in loudness depending on what brand tubes I have in it...could it be something is wrong with the amp or the tube sockets? Could it just be ground looping? My Little Dot MKIII was dead silent, so I'm slightly upset considering this amp is more than double the price...

post #488 of 7565
Quote:
Originally Posted by dxanex View Post


I just ordered a tube of Deoxit, so I'll give it a shot. I noticed the hum fluctuates in loudness depending on what brand tubes I have in it...could it be something is wrong with the amp or the tube sockets? Could it just be ground looping? My Little Dot MKIII was dead silent, so I'm slightly upset considering this amp is more than double the price...

 

Here's some instructions but instead of alcohol, use Deoxit on the tubes.

 

http://www.ehow.com/how_7963572_clean-vacuum-tube-sockets.html

post #489 of 7565

If you remove the inputs does the amp still hums? If so that is not a ground loop issue.

post #490 of 7565

What sounds better to you - 6AJ5 and 6N6P or CV4015 and 6N6P-IR?

 

This is a very good question. I will check this out in the next days, as I haven't combined 6AJ5 and 6N6P yet. But I went through four power tubes (6N6P (gold), 6N6P-I, 6N6P-IR and 6H30-EV) with the CV4015 as I just rediscovered the amazing detail of these tubes and I can share some notes I wrote down:

"Warm sound coloration": 6N6P-IR > 6N6P > 6N6P-I >> 6H30-EV

"Authority": 6H30-EV (mainly mids and treble) > 6N6P-I (balanced) > 6N6P = 6N6P-IR

 

CV4015 and 6N6P-IR give a nice amount of detail and a warm, low fatiguing sound signature. CV4015 and 6N6P-I sound a little "colder" but also "cleaner" with more authority. I suppose it is down to the overall system, which one is preferred. At the moment, I am listening to the second setup and it is very enjoyable. On the other other extreme, 6H30-EV and CV4015 give an amazing amount of detail and SQ but it is quite bright and the bass is, though qualitatively very nice, not quite well present enough for my liking.

I will have another look at the nice 6AJ5s.


Edited by Acapella11 - 11/18/12 at 4:07pm
post #491 of 7565
Quote:
Originally Posted by dxanex View Post


I just ordered a tube of Deoxit, so I'll give it a shot. I noticed the hum fluctuates in loudness depending on what brand tubes I have in it...could it be something is wrong with the amp or the tube sockets? Could it just be ground looping? My Little Dot MKIII was dead silent, so I'm slightly upset considering this amp is more than double the price...

This happened to me lately hum my mk3 was atop my other amp that was not on by the way which is close to my pc tower i just moved the LDOT away from tower and the hum stopped could be that or the tubes i had on a the time but i dont thinks its the tubes.

post #492 of 7565
Quote:
Originally Posted by john57 View Post

If you remove the inputs does the amp still hums? If so that is not a ground loop issue.


Yes it does. So then, it must be an issue with the amp and not the audio chain. I will try using the deoxit on the tube sockets next. Though I realized on my AKG K702 I don't hear the hum at all. I'm very confused, I don't understand electronics so it's frustrating trying to troubleshoot it. The seller is Chinese and his English is not the best...but the humming is not bad enough to return the amp, at least not yet.

post #493 of 7565
Quote:
Originally Posted by mordy View Post

What sounds better to you - 6AJ5 and 6N6P or CV4015 and 6N6P-IR?

 

(For the 6N6P I use 70's gold grid tubes)
 

Firstly, I need to say that this comparison is not under best conditions, as the jumpers need to be changed between comparisons and tubes are differently loud. So, certain inaccuracies are inherently given.

 

Dear Mordy, my gold grid 6N6Ps are from 1998. Using the HE-500, I have more resolution than before with my AKG Q701. Although LD MKIII is not quite the right match for a HE-500, differences between tubes can be nicely analyzed. Using this gear, the clear improvement comes from using the CV4015.

 

The 6N6P with 6AJ5 has a very defined bass, nice treble extension, great mids and builds an extended audio space. The weakness comes with the resolution. It is a little like as if everything is assembled behind a thin almost transparent curtain. The sound signature is very pleasant but the focus and transparency is just second to the CV4015.

Choice of the power tube is a matter of taste, as the 6N6P-IR gives a warm and spatial representation, but not as focused as the 6N6P-I, which extends the room lesser (less reverb e.g.). The 6N6P-I has a very clear "in-the-face" sound. I like both in their ways. The 6N6P is in between, not as warm ('seducing') as the 6N6P-IR, more definition, possibly less space. The 6N6P is a great choice, might even be the best for some. I would say, depending on the liking, resolution and brightness of your headphones and dac you would favour the one best complementing your setup.

 

Overall, for my system at the moment, the CV4015 makes all the difference and the power tube conditions it. If a similarly great to CV4015 resolving but lesser bright and a bit more bassy tube would come along, the game might change as it could complement the 6H30-EV.

 

PS: If your DAC and headphones are fine with a brighter sound (especially to avoid sharp "s"-sounds), the 6H30-EV will give the best performance with the CV4015. I have also checked the CV4014 again, and it has just amazing treble and mids, but in my setup it does lack bass.


Edited by Acapella11 - 11/22/12 at 12:52pm
post #494 of 7565

Thanks for your thoughtful review. I do not have the CV4015, but I have a pair of Mullard EF92 tubes which I think are very similar (or I may be wrong). The EF92 tubes sounded somewhat exaggerated in the treble and the bass in my system.

 

I almost always listen through speakers and to my taste the combination Tungsol 6AJ5/gold grid 6N6P is the best so far. Again, the same tubes may sound different in different systems, and part of the fun of tube rolling is to find what you like the best.
 

post #495 of 7565
Quote:
Originally Posted by mordy View Post

Thanks for your thoughtful review. I do not have the CV4015, but I have a pair of Mullard EF92 tubes which I think are very similar (or I may be wrong).
 

 

Cheers. Reading back to what Dept_of_Alchemy wrote in the beginning, it sounds like one of his preferred setups was 6N6P-I with CV4015, which is what I am listening to as I am typing this. It is a very recommendable combination. However, as you indicated, it is not the single component but the whole system that should sound according to ones liking.

Considering other nice tubes (GE JAN 5654W, Sylvania 5654W, Mullard M8100, Tung-Sol 6AJ5 etc.) - they are still great tubes but at the moment, I am locked in CV4015 mode =). I admit that the lesser power of the 6AJ5 may not be an issue with your stereo setup, but is likely to reduce the dynamics of the HE-500. They go better with a little more efficient headphones. Hence, the SQ is probably not fully reproduced. I just attached a pic of the CV4015 I am using at the moment.

 

Very best

 

700


Edited by Acapella11 - 11/23/12 at 4:50pm
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