or Connect
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Little Dot Tube Amps: Vacuum Tube Rolling Guide
New Posts  All Forums:Forum Nav:

Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 223

post #3331 of 10498
Quote:
Originally Posted by TrollDragon View Post
 

Well the clear top NEC 6AV6's are working very nicely in the LD despite my pin mishap...

 

1000

 

Here is better picture of what's inside -91 westinghouse tubes. As you can see they look identical with NEC 6AV6. I think that this dryness and sharpness in sound makes them sound more forwarding. I personally prefer just a little smoother sound. With box on the top etc types of 6AV6 could be older models and they can have smoother tube sound.

 

This tube rolling is like wine tasting. You have many excellent tubes and try to tell and explain tiny differences to the others.

post #3332 of 10498

6BE6 Status Report--

 

After a few hundred hours of burn-in, my Soviet 6BE6 tubes are running at an average temperature of 135F (after two hours of run time) with an ambient air temperature of 62F. LDIII Case near the front tubes is ~88F. The rear tubes run much hotter-near 280F at top.

 

Given my tastes in music (vocals, jazz, folk) I am not sure it makes sense to look further. Sound is crisp, good separation, excellent tone, very full but not booming. Probably not a good choice for Metallica or Queen, but otherwise worth a go. I experience lower listening fatigue than with the stock tubes. Using the Turtle Beach DSS2 as an audio source is working very well. Surround Sound is smoother through the LDIII than listening directly from the DSS2.

 

My main concern with using the heptodes was that they might pick up the signal from the AM station transmitter that resides a few hundred yards from my house. This does not happen, so these will continue to remain in use until they go bad and another pair of 6BE6 fill that space.

post #3333 of 10498
Quote:
Originally Posted by Artsi View Post
 

1000

 

Here is better picture of what's inside -91 westinghouse tubes. As you can see they look identical with NEC 6AV6. I think that this dryness and sharpness in sound makes them sound more forwarding. I personally prefer just a little smoother sound. With box on the top etc types of 6AV6 could be older models and they can have smoother tube sound.

 

This tube rolling is like wine tasting. You have many excellent tubes and try to tell and explain tiny differences to the others.

 

 

For comparison, a pair of RCA 6AV6. The NEC and Westinghouse would seem to be identical. :)

post #3334 of 10498

I have my MK III with M8100, and they sound excellent, but does anyone tube roll on the Old Little Dot II?  EF92 family, wonder if it would even be worth it.

post #3335 of 10498
Quote:
Originally Posted by KimChee View Post
 

I have my MK III with M8100, and they sound excellent, but does anyone tube roll on the Old Little Dot II?  EF92 family, wonder if it would even be worth it.

 

 

Hi Kim.

 

If you're interested, before I fell in love with the (tall-tubed) 6HM5s - which need EF95 setting - I was in love with the RCA 6DT6As which were then, and still are, excellent tubes on EF91/2 setting...

 

Cheers

post #3336 of 10498

In addition to the 6DT6A, the 6AV6 (and sister tubes, 6AT6 and 6AQ6) can also be used in the EF92 setting. However, to use these tubes, it is necessary to cut off pins 5 and 6. So yes, there are a number of very fine tubes that can be used in your LD II.

 

And in fact, these tubes would also sound great in your LD III, maybe even better than your M8100. And I would also encourage you to try the tall-tubed 6HM5 in your LD III as well.

post #3337 of 10498

While on the subject of 6AV6 (and sister tubes 6AT6 and 6AQ6), this appears to be a pair of early made-in-Holland Philips/Amperex 6AT6 (EBC90):

 

http://www.ebay.com/itm/2-Rogers-by-Philips-6AT6-EBC90-Vacuum-Tube-Tested-NOS-NIB-Holland-/121188957031?pt=Vintage_Electronics_R2&hash=item1c376cbb67

post #3338 of 10498
hi guys been really busy at work. been working almost 12-14 hours a day I'm so exhausted. thank you so much to everyone who replied me I really appreciate it. ATM I'm looking at Sylvania 6HM5 but the cheapest postage I can find is 12usd to Malaysia for a single tube...really really expensive
post #3339 of 10498
Quote:
Originally Posted by TrollDragon View Post
 

I don't see no jumpers in Red Square... :D

 

Funny man ,.you dont see him because he already jumped !:L3000:


Edited by MIKELAP - 10/6/13 at 9:56am
post #3340 of 10498
Quote:
Originally Posted by mordy View Post
 

Relevance: 0

However, this picture of a tired red square cyclist on the Red Square is good for a laugh. Perhaps the red nose indicates the reason for sleeping.....

 

http://moscow.travel/wiki/images/e/ee/Red_Square.jpg

 

Thats the kind of explanation i would like to get with pictures related to the socket mod for the double triode mod because there still things that are not clear related to soldering pins and deactivating the same pins at the base dont know what that means exactly . When somebody has the full picture and pictures it will be great meanwhile stocking up on equipement to do this thing.and practicing my soldering

:popcorn:

post #3341 of 10498
Quote:
Originally Posted by KimChee View Post
 

I have my MK III with M8100, and they sound excellent, but does anyone tube roll on the Old Little Dot II?  EF92 family, wonder if it would even be worth it.

 

Did you mean the original MK II from 2005? After that have came II+, II++ and now again II. Mine have v2.0 circuitboard and it has built-in support for the 6H30 powertubes. 


Edited by Artsi - 10/6/13 at 9:57am
post #3342 of 10498

Hi Oskari,

 

I tried to take pictures of the Siemens EH90 Foreign, Haltron 6CS6 and the Raytheon 6DT6A. All these tubes are made in Japan. It seems very clear that the Siemens EH90 and Haltron 6CS6 are identical. The Raytheon looks to have similar construction, but a little different.

Note: The Siemens box says EH90/6CS5. The 6CS5 is an error, since that is an octal tube - it should read 6CS6.

 

First a picture of the boxes and the tubes. The markings have worn off the Siemens tube from use.

The boxes are all different sizes and probably made in the countries where they were sold. Note error on Siemens box.

Closeup of the bottom mica and wires coming from the pins

Ditto

The rectangular holes in the plate are identical in the first two tubes; the Raytheon hole has a drop more height.

Top mica Haltron

Ditto

Top mica Siemens

Raytheon 6DT6A tube. Markings are P14 and underneath 3K. Anybody knows what it means?

Could not get a good shot of the top mica on the Raytheon.

Ditto

 

The Raytheon is my best sounding 6DT6 tube. The other two are also very nice sounding tubes. I believe that there were three major Japanese tube manufacturers: Toshiba, Matsushiita and Hitachi.  Oskari thinks that the first two are made by Toshiba. Regarding the Raytheon I will rely on Oskari's opinion because he has much better eyesight than me (screen resolution?) and he has the ability to identify the different clues. (If you want more pictures or different views let me know).

 

Amazing how the Phillips ghost is evident in all the Japanese, Yugoslavian and Australian tubes.....

post #3343 of 10498
Quote:
Originally Posted by MIKELAP View Post
 

Thats the kind of explanation i would like to get with pictures related to the socket mod for the double triode mod because there still things that are not clear related to soldering pins and deactivating the same pins at the base dont know what that means exactly . When somebody has the full picture and pictures it will be great meanwhile stocking up on equipement to do this thing.and practicing my soldering.

 

Hope this explanation will help a bit....

 

When we insert a 9-pin 6DJ8 or 6BQ7A into a 7-pin adaptor, we have the following:

 

Tube pin assignment  -> unmodified adapter  -> Little Dot pin-hole assignment

 

Tube pin 8 (cathode) -> pin-hole 7 (screen/suppressor grid)
Tube pin 7 (grid)  -> pin-hole 6 (screen/suppressor grid)
Tube pin 6 (plate) -> pin-hole 5 (plate)
Tube pin 5 (heater) -> pin-hole 4 (heater)
Tube pin 4 (heater) -> pin-hole 3 (heater)

 

We are fortunate that tube pins 4, 5 and 6 line up perfectly. However, we are not so lucky with tube pins 8 and 7. The Little Dot assigns the grid to pin-hole 1, not pin-hole 6; and the cathode to pin-hole 2, not pin-hole 7.

 

So we modify the adapter. We connect tube pin 8 (adapter pin 7) to adapter pin 2 to reroute the cathode to pin-hole 2, and tube pin 7 (adapter pin 6) to adapter pin 1 to reroute the grid to pin-hole 1.

 

Now that adapter pins 2 and 7 are connected and pins 6 and 1 are connected, we do not want pins 6 and 7 to extend out of the bottom of the adapter and into pin-holes 6 and 7 in the Little Dot socket. So we cut them a bit short. When you look at the bottom of the adapter, you will see only 5 pins, as the other two have been shortened.

 

Hope this helps. :)

 

PS: Very frankly, it was quite a struggle to put my adapters back to together after modification, but everything is working perfect. Therefore, I am very reluctant to take them apart in order to take pictures as I don't want to risk breaking them somehow. (>_<)

post #3344 of 10498
Quote:
Originally Posted by mordy View Post
 

I tried to take pictures of the Siemens EH90 Foreign, Haltron 6CS6 and the Raytheon 6DT6A. All these tubes are made in Japan. It seems very clear that the Siemens EH90 and Haltron 6CS6 are identical. The Raytheon looks to have similar construction, but a little different.

...

Oskari thinks that the first two are made by Toshiba. Regarding the Raytheon I will rely on Oskari's opinion because he has much better eyesight than me (screen resolution?) and he has the ability to identify the different clues.

 

Thanks for the photos! I think that they were all made by Toshiba. That they probably were.

 

You are right that the Raytheon-branded tube is a bit different but it is still quite similar.

 

You can see a Hitachi-branded 6DT6A here:

 

 

The differences between these two seem more pronounced to me.

post #3345 of 10498

Hi Oskari,

 

Thanks for your comments.Yes, it does look quite different. So Toshiba it is.

 

BTW: Is that price of $50 in USD?

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › Little Dot Tube Amps: Vacuum Tube Rolling Guide