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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 253

post #3781 of 10486
Quote:
Originally Posted by Artsi View Post
 

I rolled to my lil dot mk2 some bigger tubes. All tubes are in use. 6SN7GT is a secret ingredient! Switches are for noval base doubletriode to switch between 6.3 and 12.6v heaters etc. Sound seems to be just like it should be.

 

It looks amazing! :)

 

I wonder.... Why did you use a 6SN7 instead of a 6SL7?

post #3782 of 10486
Quote:
Originally Posted by gibosi View Post
 

 

It looks amazing! :)

 

I wonder.... Why did you use a 6SN7 instead of a 6SL7?

6SN7 works as a "power first stage". Drives both channels and 6A6s are working in parallel. I have 6SL7 too, but it won't work as good.

post #3783 of 10486
Quote:
Originally Posted by Artsi View Post
 

6SN7 works as a "power first stage". Drives both channels and 6A6s are working in parallel. I have 6SL7 too, but it won't work as good.

 

I have ordered a Tung-Sold 6SL7 and a 12AX7 to 6SL7 adapter. But while you take GIANT steps, I take baby steps! lol :)

post #3784 of 10486
post #3785 of 10486

Does anyone know which company manufactured these "Spezial" E88CC tubes?  (Oskari???)

 

From the getter structure, I assume a Philips / German company.... but which one?

 

$T2eC16V,!ykFIdtDUtPuBSY6bPVQF!~~60_12.JPG 

 

503d27892a5e9ac51657b48878d49f44a.jpg 

post #3786 of 10486

gibosi is this connection schematic on page 243 still ok. Thanks

post #3787 of 10486
Quote:
Originally Posted by MIKELAP View Post
 

gibosi is this connection schematic on page 243 still ok. Thanks

 

 

Yes, for 12AX7 tubes, this is correct. :)

 

And if you have the heaters and shield (pin 9) connected to the right LD adapter for 6DJ8 tubes, it might make things a little easier to keep the heaters on the right LD adapter, like so:

 

12AX7
 
9-pin socket           left LD socket        right LD socket
 
1 plate triode 1                5                        
2 grid triode 1                  1
3 cathode triode 1            2
4 heater                                                    3                         
5 heater                                                    3                         
6 plate triode 2                                           5
7 grid triode 2                                             1
8 cathode triode 2                                       2
9                                                              4


Edited by gibosi - 11/2/13 at 7:43pm
post #3788 of 10486
Quote:
Originally Posted by gibosi View Post
 

Does anyone know which company manufactured these "Spezial" E88CC tubes?  (Oskari???)

 

From the getter structure, I assume a Philips / German company.... but which one?

 

I'm hardly a getter specialist, and whoever took those photos is not much of a photographer. I'm sorry, but I need better clues, hopefully in focus. Even so, those are not the same tube, perhaps even different manufacturers.

post #3789 of 10486
Quote:
Originally Posted by Oskari View Post
 

 

I'm hardly a getter specialist, and whoever took those photos is not much of a photographer. I'm sorry, but I need better clues, hopefully in focus. Even so, those are not the same tube, perhaps even different manufacturers.

 

These pictures are from two different auctions, two different eBay vendors, so yes, two different Spezial tubes.

 

I have learned a little more. After contacting the vendor about the first tube, I was told Hoges made it. But we know that Hoges was not a manufacturer, but a German rebrander. So, like Halston and Zaerix, there is no way to easily know who manufactured that Hoges "Spezial" E88CC tube. From what I can see in the blurry photo, it does not resemble any European E88CC I have seen. In the tube in the second photo, a Philips-style getter is evident, but even so, this tube could have been made in GB, Holland or anywhere else Philips had a factory.

post #3790 of 10486

A couple pictures:

 

First, GE 5751. This is a premium industrial/military version of the 12AX7. Note the double layers of mica, plus a third mica just below the getter. Also note the steel rods connecting the middle and lower mica. Unfortunately, I haven't been able to spend any time with this tube.....

 

 

And second, Voskhod 6N23P, 1978, with silver shield. I would rate this tube right up there with my USA-Amperex 6922. The Amperex is just a bit brighter, but both have great detail and transparency, and are toe-tappingly musical to boot.

 

post #3791 of 10486

I have headphone measuring head that looks like this:

So here is frequency response curves for two different sounding sets of tubes with bassport modded akg K701.

1000

Lines go pretty much same, so you see clearly red line only little from start. EF93 no brand tubes sounds like s***. But it is not measurable this way.

post #3792 of 10486

Nice endeavors as usual around here, especially the Crazy Box (tm) with an extra tube stage, which the manufacturing of is way above my league lol -and to think people used to think I was doing some crazy stuff... The times, they change...

 

Anyway, meanwhile in calmer waters, I found a single - I was looking for a pair but pairs were way out of my budget- Amperex USN-CEP 6922 tube for 40 some UK pounds shipped, which isn't so bad if you look on the bright side.

 

What's interesting is that it has the exact - and I mean exact - same factory codes and date codes as gibosi's Beckman 6922 tubes. These have been getting very good (as in top tier) reviews on the Lyr thread and elsewhere, and are supposed to be somewhat selected Amperex "white label PQ" 6922 for the US Navy. It's probably the exact same tube, which was intended for premium use anyway.

 

Looking forward to comparing it with the OG tube; hopefully that'll round out the Amperex/Philips family for me (no, I won't spend $1K on pinched waist Amp'ex tubes lol). If there is a next tube, it will either be a pair (as in an end-game pair) to use in a prettier way on my IV SE, or something new and European. But the way things are looking now, I may just wind it down a little, since my last tube is already tremendously satisfying and since I expect the USN-CEP to give me the same satisfaction. A step up would immediately be something like a CCa, and I'm not using tubes that expensive on a rigged amplifier lol.

post #3793 of 10486
Quote:
Originally Posted by Artsi View Post
 

The BOXZILLA! Got finally this son of a b**** work. And i can say that the box is pretty full of stuff. 

 

1000

 

I rolled to my lil dot mk2 some bigger tubes. All tubes are in use. 6SN7GT is a secret ingredient! Switches are for noval base doubletriode to switch between 6.3 and 12.6v heaters etc. Sound seems to be just like it should be.

 

This is freaking awesome!

 

I've been lurking this thread since I bought a LDK MK III and began my tuberolling journey with the recommended tubes mentioned in the first post. After getting some old 1960's Novosibirks I thought the journey was over, then I stumbled upon posts about heptodes and pentodes and bought some of them too... then after a while after I finished reading this thread some of you rolled in double triodes and Artsi made his little box I was eager to build it myself. And now that big ass monster O_O 

 

Can you post a guide like you did with your little adapter box? 

 

And thanks to mordy, Audiofanboy, Gibosi etc.. for your constant input and new ideas. It was a blast reading everything posted in here. I made an account just because of this thread ^^

post #3794 of 10486

i'm about to buy a spare power tubes(that two big tubes in back of unit i think they are called power tubes) any suggestion on which type/brand? i saw some ECC99 are those compatible with Little Dot MK III?

post #3795 of 10486

Hi I love music 2,

 

There is much less of a selection of power tubes than driver tubes. The best are the 6H30Pi-DR/6N30-DR  tubes that today run in the $200-$250 range/pair. An excellent and much less expensive alternative is the 6N6P-IR that cost under $35/pair. Don't bother to look for anything else.

 

All these tubes are made in Russia. With the fall of communism the quality went down. It is best to look for older tubes made before 1990 and preferably from the 70's and 80's. Count on a month to receive them (sometimes faster).

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