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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 330

post #4936 of 6966
Quote:
Originally Posted by Artsi View Post
 

http://kuvaton.com/k/yYqo.jpg Needs some paint...

 

Chassis is way too small! And there is inside transformer, 15H choke etc. Do not know is there any benefit to use tube rectifier, but it makes electric field and many 6SL7 tubes are rather sensitive to it. At least with tube rectifier amp does not seem to sound worse than with diodes.

 

Amp uses AC heaters without any problem.

 

I've been looking to upgrade to the LD MK VI+ vs the WA22 and a lot of poeple said you lose some power with a tube rectifier which is a downfall if you're going to orthos like I plan to, but if you're using something high impedance in an OTL topology its up in the air whether its better or worse for SQ.

post #4937 of 6966

Hi Artsi,

 

Is the amp base a cooking pot or a cover for a heating urn?

 

Interesting that I discovered that 6SN7 tubes sounded better than 6SL7 tubes in the Little Dot just by listening.

 

Also interesting that the new Little Dot MK9 uses a Chinese variant of the 6SL7 as driver.

post #4938 of 6966

Rectifier tubes don't suffer from Solid State switching noise.

 

In some amps some people can hear it.

post #4939 of 6966
Quote:
Originally Posted by rosgr63 View Post
 

Rectifier tubes don't suffer from Solid State switching noise.

 

In some amps some people can hear it.

 

Have you seen anything that compared both side by side and measured the noise? I really like the WA22's design since it has all the luxury amenities such as the DACT attenuator and if nothing else the tube rectifier looks cool, but from $775 to $1900 i don't think i can justify it. Other than that the MK VI+ can use the same 6SN7/6SL7 driver tubes with 6080/6as7g/5998 power tubes.

 

sorry if I'm rambling the subject has just always intrigued me.


Edited by mab1376 - 2/7/14 at 12:37pm
post #4940 of 6966

Personally I haven't.

 

But I have two friends who tried it and could hear the switching noise.

They did not carry out any measurements.

 

Some of my amps use SS and others tube rectification and all sound good to me.

post #4941 of 6966

What voltage should i set my external PS for 6SL7/ 6SN7 and can i use 6SN7 as a driver tube?

post #4942 of 6966
Quote:
Originally Posted by i luvmusic 2 View Post
 

What voltage should i set my external PS for 6SL7/ 6SN7 and can i use 6SN7 as a driver tube?

 

Yes, you can use both the 6SL7 and the 6SN7 as driver tubes. In fact, the 6SN7 is a better driver tube in our LDs than the 6SL7. These are 6.3 volt tubes, so set your PS accordingly. 

post #4943 of 6966
Quote:
Originally Posted by gibosi View Post
 

 

Yes, you can use both the 6SL7 and the 6SN7 as driver tubes. In fact, the 6SN7 is a better driver tube in our LDs than the 6SL7. These are 6.3 volt tubes, so set your PS accordingly.

THANK YOU VERY MUCH!!

post #4944 of 6966
Quote:
Originally Posted by mordy View Post
 

Hi Artsi,

 

Is the amp base a cooking pot or a cover for a heating urn?

 

Interesting that I discovered that 6SN7 tubes sounded better than 6SL7 tubes in the Little Dot just by listening.

 

Also interesting that the new Little Dot MK9 uses a Chinese variant of the 6SL7 as driver.

We had spare 180mm diameter aluminium block at work and i lathed it to amp chassis. 250mm would have been much better, this was too small.

 

Those chinese 6SL7 variants are either russian copies or even made with old russian machinery. I'm pretty sure that MK9 should work fine with 6SN7 as driver too.

post #4945 of 6966

I received a gray smoked-glass National Union 6SN7GT yesterday. These were manufactured earlier than the more common black smoked-glass tubes, prior to 1949 I believe. At first glance, one might think this tube is an RCA from the same time period. However, there are two distinguishing characteristics. Both the RCA and the NU have mica spacers attached to the top mica, similar to the those on the TungSol mouse ears. However, in the RCA they are rectangular in shape, whereas in the NU they are square. But the most noticeable difference is the NU has U-shaped structures, used to spring-load the plates, located on the top mica, similar to the TungSol BG/RP.

 

The vendor didn't know anything about this tube and as I didn't know what it was either, I asked rosgr63 if he would be kind enough to take a look. So I got 5 tubes for $99 including a TungSol BG/RP, Sylvania VT231, Raytheon VT231 and a GE 6SN7GTA. For $25 a tube, I am pleased. :)

 

I listened to it for a while last night and found it very enjoyable. (But it seems I find almost all the 6SN7s enjoyable! lol ). As others have written, it has a lush and somewhat forward mid range, with good bass and treble. Comparing this to the black-glass version has now been added to my very, very long to-do list. If you stumble across one of these at a good price, as I did, I think you will find it to be a very nice tube.

 

 

post #4946 of 6966

Which side i need to connect the ground wire from LD chassis  to Voltage Regulator In or out?

post #4947 of 6966

This is a rare tube, a nice and lucky find which you are going to enjoy.

 

Better sounding IMHO than the later NU with the black glass coating.

post #4948 of 6966
Quote:
Originally Posted by i luvmusic 2 View Post
 

Which side i need to connect the ground wire from LD chassis  to Voltage Regulator In or out?

Out, like so:

 

post #4949 of 6966
Quote:
Originally Posted by gibosi View Post
 

Out, like so:

 

THANK YOU! I'am almost done with the adapter again THANK YOU!

post #4950 of 6966
Quote:
Originally Posted by rosgr63 View Post
 

This is a rare tube, a nice and lucky find which you are going to enjoy.

 

Better sounding IMHO than the later NU with the black glass coating.

 

And again, thanks for ID-ing this tube for me before I purchased it! I do indeed feel very fortunate to have stumbled on this tube for such a good price.

 

After doing a very quick A/B comparison between the gray glass and black glass, I think I prefer the gray glass, as well. While I find the black glass to have a very beautiful sound, it is rather dark with a fairly heavy bass presence. The gray tube has a much more balanced tonal balance, from top to bottom. Since I have only one tube in my system, I do not have the luxury of matching two different 6SN7s to adjust tonal balance. For example, I have read that combining the strong bass of the black glass NU with the weaker bass but better mids and highs of the Sylvania VT231 often works very well. But in my system, one tube has to do it all, and the gray glass is the clear winner.

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