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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 72

post #1066 of 7488

Tube Pin Numbering 101

 

 

Hold the tube in your hand, upside down, with the pins facing up. Orient the widest gap between the pins to be closest to your body. Now compare the tube in your hand to the basing diagram above. The pin just to the left of the gap is pin 1. Count clockwise ending at the pin just to the right of the gap, pin 7.

 

The 6J4 triode

 

The diagram above is for the 6J4, the triode that AFB and I are currently trialing.

 

The list of terminal connections, to the left of the basing diagram, indicates that the grid is tied to pins 1, 5 and 6. Whatever the reasons for having three pins tied to the grid, for our purposes, only one pin is required, and normally that is pin 1. Therefore the grid connections on pins 5 and 6 are not necessary and can be eliminated. Also note that the plate is tied to pin 7. However, our LDs expect the plate to be connected to pin 5, so we need to get the 6J4s plate on pin 7 connected to pin 5. But it just so happens that the purpose of the EF92 jumper is to connect pins 5 and 7.

 

Therefore, we sever pins 5 and 6 to eliminate the superfluous grid connections, and then we set our LDs up in the EF92 configuration to get the plate connected properly. Once done, everything is good. :)

 

Edit: No little wires connecting pins in the socket are required to use this tube. So it couldn't be simpler. EF92 and sever two pins!


Edited by gibosi - 4/17/13 at 5:44pm
post #1067 of 7488

Tubes and CRT's

EIA co
Amperex (USA)  111
Bendix 125
DuMont 158
Eimac (Eitel-McCullough, Inc) 162
Electronic Tube Corp 169
General Electric Co (USA) 188
Hytron (CBS-Hytron) 210
Machlett 231
RCA (Radio Corp of America) 274
Raytheon 280
Superior Tube Co 310
Sylvania (Hygrade Sylvania Corp) 312
Tung-Sol 322
United Electronics 323
Western Electric 336
Westinghouse 337
Zenith Radio Corp (CRT's) 343
Nortn American Philips Corp 423
Taylor (aka Cetron-Taylor) 713
Lewis & Kaufman 738
National Electronics (also Cetron) 749
Penta Laboratories 771
Vacuum Tube Products 781
Varian Associates 809
Litton Industries 879
Electrons, Inc 935

 

Dear AFB,

 

I was reading about your post about the Motorola 6J4 tubes where you wondered if Motorola made their own tubes or if these were rebranded. As can clearly be seen on the picture of the Motorola tube there is a number 274 printed on the tube, which identifies them as made by RCA - just check the enclosed chart.
 

post #1068 of 7488
Quote:
Originally Posted by mordy View Post

Do these tubes also require the EF95 setting with pins 2&7 strapped?

 

Regarding the Sylvania 1977 tubes: When looking for tubes for my MKIII I came to the conclusion that 1970's Sylvania tubes were still high quality, but GE tubes declined in quality in the 70's and later.
 

 

Actually, some specific GE tubes made in the late 70s still seem to sound good -my GE 6485 made and packed in 1978 definitely do- so for special non-mil-spec but industrial-computer rated tubes, you should still be fine diving into the not-so-old GE tube stocks. On the other hand, for anything consumer-grade or military, I would stay away from 70 and 80s GE tubes, as there is a clear decline (probably from when GE made those last "lifetime supply" batches for the US gov't and army).

 

As gibosi said, the easiest way to use 6J4/8532 tubes is to use the EF92 jumper setting -and to chop off pins 5+6. I'm still not very comfortable using the jumper to actually conduct the output amplified signal from pin 7 to pins 5/6 -and I hate changing jumpers- but I just can't see an easy way to strap pins 5 and 7 at the socket level, not solidly at least.

post #1069 of 7488

As long as staying on the tube side of things, the pin numbering is straight forward I suppose because it is exactly as on the data sheets. Only, when looking at the socket, I was so much tempted by the pin north of the gap to be # 1, lol, although it obviously must be the one south of the larger gap! Hence, for the tube side, I suggest, just use one of the data sheets, Gibosi's on this page for example. Then for the socket side, a simple reminder is "Seven Up" ;)

 

Tubes: Today, I received the 6AH6 type Tung-Sol 6485 tubes. I have just put them in, and they sound really good. One word: Stage! The stage is wide, feels very nice. Slightly wet, as in nice reverb. That enhances the stage feeling too. Transparent, that's what they are, wow. Great open sound. The bass is very punchy. It is almost, you think it's not there, that's how clean they sound, until, when it kicks in - it kicks the shiit out ouf you. I wouldn't mind a little more weight in the bass section but they still seem pretty well balanced across the spectrum, which I find quite important. They sound neutral too, surely in the CV4015 signature direction. More on that later but they could become my go to tubes L3000.gif Good stuff, and so far, (even) more impressive than the GE 8425 (6AU6 type). Tube code is 3227106-3, which I interpret as Tung Sol (thanks Mordy :) ) and 6th week of 1971.

Best

 

PS: Don't want to pester you with pics but I can take one if you are interested. :)


Edited by Acapella11 - 4/18/13 at 12:32pm
post #1070 of 7488

Pictures are always welcome.

 

I must say that I find it a little hard to keep up with you guys and all the new stuff you are trying, and I also find it difficult to keep up with the alphabet soup and numbers of all the different tubes.

 

First, I would like to hear a consensus and ranking about which tubes are the best sounding (as AFB did in the past). Then, after each tube, a line with the settings required. An example would be like this:

 

1)Super Duper 6ABCDEFGWA EF95 setting with pins 2&7 strapped

2)Electron Fabulosi 3995 EF92 setting with pins 5&6 snipped off

3)Unobtanium 4892i EF91 setting with liquid cooling

 

The tube names are all a joke, of course, but it would be nice to have a little chart to go by. I am still working on the mirror image pin numbering....Let's see, if I look down on the empty socket of the LD driver tube, the top left is #7, but if I look at a tube with the pins facing me, and the bigger gap on the left, the bottom left is #7.

Did I get it right?
 

post #1071 of 7488
Quote:
Originally Posted by Acapella11 View Post

As long as staying on the tube side of things, the pin numbering is straight forward I suppose because it is exactly as on the data sheets. Only, when looking at the socket, I was so much tempted by the pin north of the gap to be # 1, lol, although it obviously must be the one south of the larger gap! Hence, for the tube side, I suggest, just use one of the data sheets, Gibosi's on this page for example. Then for the socket side, a simple reminder is "Seven Up" ;)

 

Tubes: Today, I received the 6AH6 type Tung-Sol 6485 tubes. I have just put them in, and they sound really good. One word: Stage! The stage is wide, feels very nice. Slightly wet, as in nice reverb. That enhances the stage feeling too. Transparent, that's what they are, wow. Great open sound. The bass is very punchy. It is almost, you think it's not there, that's how clean they sound, until, when it kicks in - it kicks the shiit out ouf you. I wouldn't mind a little more weight in the bass section but they still seem pretty well balanced across the spectrum, which I find quite important. They sound neutral too, surely in the CV4015 signature direction. More on that later but they could become my go to tubes L3000.gif Good stuff, and so far, (even) more impressive than the GE 8425 (6AU6 type). Tube code is 3227106-3, which I interpret as Tung Sol (thanks Mordy :) ) and 6th week of 1971.

Best

 

PS: Don't want to pester you with pics but I can take one if you are interested. :)

 

Aaah! Glad to see a third person saying the Tung-Sol 6485 are great tubes, and potentially the best they have. One of mine died quickly after burning in, but I should get my -free- replacements by the end of the week or early next week, and be able to report back on these more thoroughly.

 

Right now, in terms of detail their only true rival is the French 6J4S tubes I have, and to a smaller extent the Valvo/Mullard EF94 and GE 6485; definitely a world above the GE 8425A. These have punchier bass that goes down low but I did like how the bass on the 6485 type -its only "default" imo- is unobtrusive and just there and nice behind the details; though I wouldn't mind a bit more punch/power in the low end, which might in turn hide some details.

 

Tradeoffs really... Musical, mellow and a little bassy or ultra-detailed and balanced -read occasionally treble-oriented- with a great stage.

 

Just one question Acapella, your TS 6485 are transparent and have an O-getter right, the latest construction? Just curious if there's an older construction out there too, like for the GE.

post #1072 of 7488
Quote:
Originally Posted by mordy View Post

Pictures are always welcome.

 

I must say that I find it a little hard to keep up with you guys and all the new stuff you are trying, and I also find it difficult to keep up with the alphabet soup and numbers of all the different tubes.

 

First, I would like to hear a consensus and ranking about which tubes are the best sounding (as AFB did in the past). Then, after each tube, a line with the settings required. An example would be like this:

 

1)Super Duper 6ABCDEFGWA EF95 setting with pins 2&7 strapped

2)Electron Fabulosi 3995 EF92 setting with pins 5&6 snipped off

3)Unobtanium 4892i EF91 setting with liquid cooling

 

The tube names are all a joke, of course, but it would be nice to have a little chart to go by. I am still working on the mirror image pin numbering....Let's see, if I look down on the empty socket of the LD driver tube, the top left is #7, but if I look at a tube with the pins facing me, and the bigger gap on the left, the bottom left is #7.

Did I get it right?
 

 

I think I had a picture of the sockets a few pages back (probably 15 by now, but it's on my profile I think) with showed pins 2 & 7 socket strapped. I still use that picture as an absolute reference when I have a doubt, so I don't make a mistake. Once you've strapped a few tubes at the socket level, and snapped some pins of another couple of tubes, you'll start to know pretty instinctively what you're doing. When in doubt, I also often check to see which pins go to the heater (usually pins 3 & 4, at least on all the "compatible" tubes I've tried) in a tube -which you can usually pretty easily see- that way i can know for sure what pins are where from there.

 

I could try to make a quick list, but I just don't have that much time and may not be able to update it often, which in turn could be risky for people using it that haven't been around long enough... But right now, there are only so many new non-native types, it is still easy:

 

- 6CB6 / 6CJ6 / 6676 -> EF92 jumper (or strap pins 2 & 7 at the socket level (wire mod))

- 6DK6 / 8136 -> EF92 jumper (or strap pins 2 & 7 at the socket level (wire mod))

- 6GM6 -> EF92 jumper (or strap pins 2 & 7 at the socket level (wire mod))

- 6EW6 -> EF92 jumper (or strap pins 2 & 7 at the socket level (wire mod))

- 6GY6 / 6GX6 - EF92 jumper (or strap pins 2 & 7 at the socket level (wire mod))

- 6AG5(WA) / 6J3P(-E) / 6BC5 / 6CE5 / EF96 / 6186 -> EF95 jumper

- 6AU6(A/WA/WB/WC) / 6136 / 8425A / EF94 -> EF95 jumper + strap pins 2 & 7 at the socket level (wire mod)

- 6AH6(WA) / 6485 -> EF95 jumper + strap pins 2 & 7 at the socket level (wire mod)

- 6J4 / 8532(W) -> EF92 jumper + snap off pins 5 & 6 (snap & tape (?) mod -do make sure you tape over the leftover stubs so you don't electrocute yourself or make your amp explode, think of the children)

 

Don't hesitate to copy and paste this and improve it, I just threw this together as a temporary list... I still thoroughly recommend to go back 10-30 pages and read over whole sections when in doubt, as everything is written there quite precisely and without that much spam between messages, and it's still the best way to avoid mistakes. Like someone mentioned a while back, we've succeeded in keeping this thread polite and clean, and therefore fairly convenient to read over lol.

 

Edit: With little doubt, my current tube order is (I'll limit myself to the top A+++ tubes): Tung-Sol 6485, GE 6485, Valvo/Mullard EF94, "the brand new 6J4 triodes" (to be confirmed obviously, but my French 6J4S and the Sylvania 8532W gibosi tested are an extremely good start)

 

Quoting and editing myself from page 60 for the rest:

1 (A++) - GE 8425A/6AU6A (check with gibosi for the other best 6AU6 like the Sylvanias which I haven't tested)

2 (A+) - GEC CV4014

3 (A or A+ depending on headphone impedance) - Mullard CV4015

4 (A) - GE 6GM6, 6EW6, 6GX6/6GY6

5 (A- to B+) - GE 8136, 6CB6A, Mullard CV4014/M8083 (Mitcham), Tung Sol 6AJ5, Mullard CV4010/M8100, Voskhod 6J1P-EV (Gold grids), Mullard CV5377 (Mitcham), Mullard CV4014 (Whyteleafe)

6 (B to C+) - Brimar CV4014, Mullard CV138/6AM6, Voskhod 6J1P-EV (Non-gold grids), Brimar CV138, Mullard CV850 (Whyteleafe), Tung Sol 6AK5 (side getter, early shape, 1943), GE JAN 5654W

 

That's about all I can give you at this point, which should sum up quite a bit of information I think. Again, the detailed reviews and pics are all in the last few dozen pages with the right keywords to search for (even I keep getting lost here looking for information we posted like... 3 weeks ago...).

 

Edit 2: use tape with 6J4 pins you snap off

 

Edit 3: all non-LD-compliant (non EF92/91) tubes that work with the EF92 jumpers, also work just as well with the pin 2 & 7 wire mod at the socket level.


Edited by Audiofanboy - 4/18/13 at 1:34pm
post #1073 of 7488

Wow, I am so impressed withe these TS 6485, can't stop listening =).

 

Audiofanboy:

 

And, correctly, I read back in the thread, after, I wrote my first impressions and here was your comment:

 

Quote:
...more of those so-realistic-voices-you-wonder-what-you'd-been-listening-to-all-those-years -seriously- and apparently even better detail extraction -again the finger snaps on Billie Jean but this time they're not just audible but right there above Michael nice and dry and snappy with a realistic reverb in the room, mesmerizing really-...

 

Just what I wrote and thought. ;) They are really good. My number one at the moment.

 

In order to answer the question in the best possible way, Audiofanboy, I made a shot. They surely are worth a good picture, and yes, O-getter and transparent. Big disadvantage of taking the pic was that I had to stop listening, haha ;)

 

 

 

Mordy, OK, that was good for the socket side (seven up), but for the tube side, the left one bordering the long gap is number 1. Just hold your finger onto it whilst inserting the tube ;). You will be getting the hang of it =)


Edited by Acapella11 - 4/18/13 at 1:24pm
post #1074 of 7488
Quote:
Originally Posted by Audiofanboy View Post

Just one question Acapella, your TS 6485 are transparent and have an O-getter right, the latest construction? Just curious if there's an older construction out there too, like for the GE.

 

Just an FYI, at the bottom of page 67 there is a picture of my mid 1960's TS 6485s. These are transparent but have the older square getter. So yes, there is an older construction out there....

post #1075 of 7488

Thanks, very helpful.

 

The page with the picture of the 2-7 strap is on page 59 on the blog, and I have printed it out and used many times.

 

The last entry on your list should definitively also state to tape the snapped off pins:

 

- 6J4 / 8532(W) -> EF92 jumper + cut off pins 5 & 6 and tape stubs (cut & tape mod)

 

Did you get my message that the Motorola 6J4 tubes were made by RCA?
 

post #1076 of 7488
Quote:
Originally Posted by Acapella11 View Post

Wow, I am so impressed withe these TS 6485, can't stop listening =).

 

Audiofanboy:

 

And, correctly, I read back in the thread, after, I wrote my first impressions and here was your comment Audiofanboy:

 

 

Just what I wrote and thought. ;) They are really good. My number one at the moment.

 

In order to answer the question in the best possible way, Audiofanboy, I made a shot. They surely are worth a good picture, and yes, O-getter and transparent. Big disadvantage of taking the pic was that I had to stop listening, haha ;)

 

 

 

Mordy, OK, that was good for the socket side (seven up), but for the tube side, the left one bordering the long gap is number 1. Just hold your finger onto it whilst inserting the tube ;). You will be getting the hang of it =)

 

Haha, at least it's reassuring to see we get similar impressions and wording to describe tubes, and it shows it can't all be placebo effect or random fluffy impressions we've been posting...

 

Reading back a few pages to fill in the gaps in my previous post, I realized that gibosi's TS 6485 actually have a square getter (made in early 60s), so yes there have been different versions made with an change in construction -like most tubes between the 50s and 60s.

 

I'll stop posting for a day or two now to let the thread balance itself a little, if you'll excuse me lol...

post #1077 of 7488

Audiofanboy,

 

Very good idea. Little addition for the 6EW6 and 6CB6 tubes:

 

- 6CB6 / 6CJ6 / 6676 -> EF92 jumper or EF95 jumper with pin 2-7 pin socket bridge / wire mod (please confirm gibosi / audiofanboy)

- 6DK6 / 8136 -> EF92 jumper

- 6GM6 -> EF92 jumper

- 6EW6 -> EF92 jumper or EF95 jumper with pin 2-7 pin socket bridge / wire mod

- 6GY6 / 6GX6 - EF92 jumper

- 6AG5(WA) / 6J3P(-E) / 6BC5 / 6CE5 / EF96 / 6186 -> EF95 jumper

- 6AU6(A/WA/WB/WC) / 6136 / 8425A / EF94 -> EF95 jumper + strap pins 2 & 7 at the socket level (wire mod)

- 6AH6(WA) / 6485 -> EF95 jumper + strap pins 2 & 7 at the socket level (wire mod)

- 6J4 / 8532(W) -> EF92 jumper + snap off pins 5 & 6 (snap & tape (?) mod)

 

Mordy,

 

I have only tried 4 of the new tubes and for me, between those, the ranking is:

1) Tung Sol 6485 (6AH6, year 1971), still burning in

2) GE 8425/6AU6

3) Sylvania 6EW6

 

I have to more thoroughly check out some GE 6GY6/6GX6 but they were a bit too bass light for my liking and not as balanced, so I think, I would put them on place 4.

 

I will later post more notes on the GE 8425 and the developing TS 6485.


Edited by Acapella11 - 4/18/13 at 1:39pm
post #1078 of 7488

Great!

 

When this list has been finalized I think that I am going to frame it and hang it on the wall next to the LD MKIII!beerchug.gif
 

post #1079 of 7488
Quote:
Originally Posted by mordy View Post

Did you get my message that the Motorola 6J4 tubes were made by RCA?

Actually, the Motorola 6J4s were my tubes. :)

 

When I got the Sylvanias and compared them to the Motorolas, they looked to be identical, with the exception of thicker mica, so I just assumed that Sylvania made the Motorolas. After reading your message, it does indeed seem that RCA made them. What I find intriguing is that the RCA tubes and the Sylvania tubes look like they could have been made in the same factory. But usually, there are noticeable construction differences between brands. So it appears that RCA and Sylvania were producing identical tubes? And now I am wondering... Do AudioFanBoy's French 6J4S look different than the American tubes? Or the same?


Edited by gibosi - 4/18/13 at 1:40pm
post #1080 of 7488
Quote:
Originally Posted by mordy View Post

First, I would like to hear a consensus and ranking about which tubes are the best sounding (as AFB did in the past). Then, after each tube, a line with the settings required. An example would be like this:

 

1)Super Duper 6ABCDEFGWA EF95 setting with pins 2&7 strapped

2)Electron Fabulosi 3995 EF92 setting with pins 5&6 snipped off

3)Unobtanium 4892i EF91 setting with liquid cooling

 

Standard disclaimer: "Old ears and cheap gears" :) 

 

But it is worth keeping in mind that we have different electronics, different headphones/speakers and different preferred "sound signatures". So while I think we can agree on the best tubes, we will likely have different rankings among them:

 

1. Sylvania 6J4/8532W EF92 setting, pins 5&6 cut, and stubs either taped or sealed with paint/varnish (I got some nail polish!)

2. Sylvania 6AU6/6136 EF95 setting, pins 2&7 strapped

3. GE 6485 EF95 setting, pins 2&7 strapped

4. TS 6485 EF95 setting, pins 2&7 strapped

 

And I received a pair of Westinghouse 6AU6/8425As today, but haven't had a chance to do more than unpack them....

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