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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 296

post #4426 of 10502
Hi, I skimped through but interesting thread. I was interested in the Little Dot MKII. Would it be possible to roll 2x GE JAN 5814A tubes in those?
post #4427 of 10502
Quote:
Originally Posted by Sumor View Post

Hi, I skimped through but interesting thread. I was interested in the Little Dot MKII. Would it be possible to roll 2x GE JAN 5814A tubes in those?

 

5814A appears to be an industrial version of the 12AU7. Therefore, if you set up your LDII to run 9-pin dual triodes, you can use these tubes. All you have to do is configure the heaters on your 9-pin socket so that you can run the 12AU7 tubes on 6.3 volts like so:

 

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/3630#post_9911760

 

Cheers

post #4428 of 10502
Quote:
Originally Posted by mordy View Post

 

Can anybody suggest inexpensive driver tubes that may work well with the higher current external power source for the heaters. The only thing that comes to mind is the 6SN7GT octal, but I remember seeing others being mentioned.

 

Has anyone suggested 6CG7 / 6FQ7? These are electrically equivalent to the 6SN7GT, but in a miniature 9-pin form, and therefore, like the 6SN7, they require 600ma. Further, they appear to be pin-compatible with the 6DJ8, so easy. There is also an 8 volt version, 8CG7

post #4429 of 10502

There has been some speculation that when running tubes with an internal shield, such as the 6DJ8, it might be preferable to tie the shield directly to ground. This evening, I did just that. I tied the shield to the same chassis screw grounding the external heater circuit. But unfortunately, the ground hum persisted..... So until we learn better, it appears that we should continue to tie the shield to the cathode of the right triode. That is, tie pin 9 to pin 8 for 6DJ8-type tubes.

post #4430 of 10502
Looks complicated gibosi, I'm totally lost. Got ebay links to the adapters and anything that is required to begin? Cheers
post #4431 of 10502
Quote:
Originally Posted by Sumor View Post

Looks complicated gibosi, I'm totally lost. Got ebay links to the adapters and anything that is required to begin? Cheers

 

Yes, it is a little complicated. Little Dots were never intended to run double triodes, so you will have to cobble together an adapter of some sort. My best advice is to start reading on page 220 of this thread. This is the point where we begin to experiment with different ways to use these tubes.

 

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/2985#post_9817399

 

In this way, you can understand what is necessary to run double triodes, and you can see a number of adapters, from shiny copper steampunk to my flying spaghetti contraption. Yes, it will take some time to read through the last 96 pages, but again, it is a little complicated. Once you had done that and have decided how you wish to proceed, we are here to help. :)

 

Cheers

post #4432 of 10502
Quote:
Originally Posted by gibosi View Post
 

 

Yes, it is a little complicated. Little Dots were never intended to run double triodes, so you will have to cobble together an adapter of some sort. My best advice is to start reading on page 220 of this thread. This is the point where we begin to experiment with different ways to use these tubes.

 

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/2985#post_9817399

 

In this way, you can understand what is necessary to run double triodes, and you can see a number of adapters, from shiny copper steampunk to my flying spaghetti contraption. Yes, it will take some time to read through the last 96 pages, but again, it is a little complicated. Once you had done that and have decided how you wish to proceed, we are here to help. :)

 

Cheers

 

Good Lord... Has it really almost been 100 pages since the "Flying 12AT7" experiment? Time flies... Not that I have any regrets about switching over to double triodes, as it's been by far the largest improvement on my amp!

 

I'm hoping to be able to give impressions of the three different Amperex (Philips) tubes I ordered by the end of month - either before or after the usual new year's eve craziness.

 

Even though my current 1960 E188CC are outrageous, the wait is kind of killing me, considering I'm also expecting a mains filter (same one Acapella presented 6 months back), a new silver-plated OCC interconnect and headphone cable, new pads for my HE-500, and that none of these seem to be getting to me very fast... I usually like to make changes one by one, so it easier to analyze the differences; but this time around I might kind of get everything at once, so I'm hoping I'll still be able to pick out the improvements brought by each separate element.

post #4433 of 10502

Hi Gibosi,

 

" 6CG7 / 6FQ7  - These are electrically equivalent to the 6SN7GT, but in a miniature 9-pin form, and therefore, like the 6SN7, they require 600ma. Further, they appear to be pin-compatible with the 6DJ8,"

 

So, if I understand you correctly, I could plug in the 6CG7/6FQ7 tubes directly into my 6DJ8 adapter, and then use a separate external power supply with a voltage regulator to power the heaters and this would work with the MKIII without any other modifications?

 

Could I use an 8V tube in the LD MKIII if I had the voltage regulator with external power supply and set the heater voltage at 8V?

 

If this is correct, could I also use 7DJ8 tubes in the LD?

post #4434 of 10502
Mordy,

I briefly looked into the same thing and it looks like that would work. I had been trying to research the next step in our tube journey while I catch up on 6dj8's lol
post #4435 of 10502
Quote:
Originally Posted by mordy View Post
 

So, if I understand you correctly, I could plug in the 6CG7/6FQ7 tubes directly into my 6DJ8 adapter, and then use a separate external power supply with a voltage regulator to power the heaters and this would work with the MKIII without any other modifications?

 

Could I use an 8V tube in the LD MKIII if I had the voltage regulator with external power supply and set the heater voltage at 8V?

 

If this is correct, could I also use 7DJ8 tubes in the LD?

 

Yes, Yes and Yes. :)

 

Yes, since the 6CG7/6FQ7 draws 600ma, more than we think the LD can safely provide, it is recommended that you use an external ps.

 

Yes, if you have an external ps, you can easily "dial in" 8 volts and you are good to go. Since this is a bit of an oddball voltage, these tubes tend to be pretty cheap.

 

And yes, although, actually you can safely use 7DJ8 tubes with 6.3 volt heaters, no problem. This is common practice among the Schiit Lyr crowd, and I have used a number of 7DJ8/PCC88s (Tesla, Valvo and Siemens) in my amp and they work fine. But if you want to be "datasheet perfect", you can dial in 7 volts. :)

post #4436 of 10502
Quote:
Originally Posted by Audiofanboy View Post
 

Even though my current 1960 E188CC are outrageous, the wait is kind of killing me, considering I'm also expecting a mains filter (same one Acapella presented 6 months back), a new silver-plated OCC interconnect and headphone cable, new pads for my HE-500, and that none of these seem to be getting to me very fast... I usually like to make changes one by one, so it easier to analyze the differences; but this time around I might kind of get everything at once, so I'm hoping I'll still be able to pick out the improvements brought by each separate element.

 

Santa is coming early to your place! I sure hope he will have at least a trinket or two left for me! lol :)

 

Currently, my (probably identical to yours) 1960 Heerlen E188CC and 1975 (October) Voskhod are my two top tubes. They are both very quiet, with great detail, and superb flow and liquidity. The Voskhod seems to have a bit more bass presence, with a bit more punch, and the mids are just a bit less forward, but otherwise, they have a very similar sonic signature. I find myself preferring the Voskhod by a hair. However, I don't think the Voskhod is "better". I think it is the synergy between the Voskhod and the rest of my system that is just a little better....

 

Next, I want to spend some serious time with the Western Electric 396A/2C51. But first, I think I will take a short break and try to simply enjoy my amazing LD 1+... :)

post #4437 of 10502
Quote:
Originally Posted by gibosi View Post
 

 

Santa is coming early to your place! I sure hope he will have at least a trinket or two left for me! lol :)

 

Currently, my (probably identical to yours) 1960 Heerlen E188CC and 1975 (October) Voskhod are my two top tubes. They are both very quiet, with great detail, and superb flow and liquidity. The Voskhod seems to have a bit more bass presence, with a bit more punch, and the mids are just a bit less forward, but otherwise, they have a very similar sonic signature. I find myself preferring the Voskhod by a hair. However, I don't think the Voskhod is "better". I think it is the synergy between the Voskhod and the rest of my system that is just a little better....

 

Next, I want to spend some serious time with the Western Electric 396A/2C51. But first, I think I will take a short break and try to simply enjoy my amazing LD 1+... :)

 

Really?! So you basically rate the - actually difficult to get a hand on - 1975 Voskhod above the early US Amperex 6922, if I understand correctly? Interesting. Of course the best Voskhod tubes are almost as hard to find as some crazy Philips tubes now, albeit less expensive, so that doesn't even help that much lol...

 

Again, I'm waiting on those three Philips-group tubes I ordered mainly for the pleasure of listening to them, but also to essentially get a feel for what "ceiling" or "limit" exists in that tube family.

 

For all I know, I might discover that, contrary to common folklore, the 7L4 non-pinched-waist Holland E88CC is better or as good as the 7L3 PW E88CC, or that the earliest US 7308 are better or whatnot. Who knows...

 

At this point where many here on this thread would rather ramp things down, I find myself kind of looking for a "standard meter" of sorts, against which I could basically gauge other tubes, even if it meant paying a little extra for it. Hopefully, at least one of those three tubes should give me a good idea of wherein the "small signal tube" limit lies.

 

Or not... Seeing as there's always been something better up to here...

 

Looking forward to your review of the 396A! Again, I just hope it will either show us the way of new and better tubes, or just help us narrow tube types down. Anything in between will just be complicated to manage and take a toll on my wallet again lol...

post #4438 of 10502
Quote:
Originally Posted by Audiofanboy View Post
 

 

Really?! So you basically rate the - actually difficult to get a hand on - 1975 Voskhod above the early US Amperex 6922, if I understand correctly? Interesting. Of course the best Voskhod tubes are almost as hard to find as some crazy Philips tubes now, albeit less expensive, so that doesn't even help that much lol...

 

Looking forward to your review of the 396A! Again, I just hope it will either show us the way of new and better tubes, or just help us narrow tube types down. Anything in between will just be complicated to manage and take a toll on my wallet again lol...

 

Yes, given my ears and gear, I rate the 1975 Voskhod better than the 1960 Heerlen E188CC and the 1961 US-Amperex 6922, but again, only by a very slim margin.

 

There appear to be four different versions of the Voskhod 6N23P manufactured in 1975. My favorite has grey plates with the getter supported by what appears to be a sheet-metal extension of the shield. I also have another 1975 Voskhod, with grey plates and a wire getter support rod, but I have not spent any time with it. Ahh....  Something else I need to do!  lol  Further, I am searching for the other two 1975 versions, both with silver shields.....

 

And yes, I am very curious to discover if the 396A can present a real challenge to the 6DJ8....  But all in good time... :)

post #4439 of 10502
Quote:
Originally Posted by gibosi View Post
 

 

Has anyone suggested 6CG7 / 6FQ7? These are electrically equivalent to the 6SN7GT, but in a miniature 9-pin form, and therefore, like the 6SN7, they require 600ma. Further, they appear to be pin-compatible with the 6DJ8, so easy. There is also an 8 volt version, 8CG7

 

This is my collection of 6CG7/6FQ7.

From the left we have 2 Super Radiotron 6CG7 made in Australia, then what I think is an RCA with side getter, labelled 6CG7/6FQ7, and lastly, and probably the best, an Amperex labelled 6CG7/6FG7 , made in USA with what looks like the GE pattern of dots.

I have only tried the Amperex so far and it sounds similar to the 6SN7 with the same wonderful soundstage.

The tubes labelled 6FQ7 don't have an internal shield and I believe this is the only difference compared to the 6CG7. Supposedly the shield eliminates any crosstalk so they are more sought-after but for us they are easier to use as there is no problem of where to ground the shield.

post #4440 of 10502
Is 20$a tube a good deal for 1975 Voskhod's?
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