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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 239

post #3571 of 7352
6V tube types
 
ECC88 6DJ8 6N23P CV5358 M3624        0.35A 33x
E88CC 6922 CCa CV2492 CV2493 9622  0.30A 33x
E188CC 7308 CV4108                         0.35A 33x
E288CC 8223                                    0.47A 25X
ECC85 6AQ8 B719 6L12                      0.44A 57X
ECC86 6GM8 6N27P                           0.30A 14X
ECC189 6ES8                                   0.36A 31X
ECC804 6GA8 6/30L2                         0.30A 18X
ECC812                                          0.44A 50X
ECC865                                          0.44A 58X
ECC180 6BZ7 6BQ7 6BS8 6T27           0.40A 36X
6N2P 6CC41                                    0.34A 100X
6BK7                                              0.45A 40X
6BC8 6BZ8                                      0.40A 35X
 
12V tube types
 
ECC83 12AX7 B339 95-127-01 6L13 CM1        0.30A 100X
ECC82 12AU7 B329 95-126-01 CC82E CV491  0.30A 17X
ECC81 12AT7 B152 CC81E CV455                 0.30A 60X
E81CC 12AT7WA CV6091 6201                     0.30A 60X
E82CC 6189 M8136 6189W                         0.30A 17X
E83CC 12AX7WA 6057                              0.30A 100X
E180CC CV8431 7062                               0.40A 50X
E181CC                                                  0.40A 32X
ECC186 12AU7WA 7316                              0.30A 17X
ECC802S                                                 0.30A 17X
5751 GL5751 CK5751 CV4017                      0.35A 70X
5814A CK5814-A                                      0.35A 17X
5963 CV3900                                           0.30A 21X
5965 6829                                               0.45A 47X
6679                                                      0.30A 60x
7025                                                      0.30A 100X
12AD7                                                   0.45A 100X
12DF7                                                   0.30A 100X
6680                                                     0.30A 20X
6211                                                     0.30A 27X
 
And you can add 12AZ7 as well - thanks for your list
post #3572 of 7352

About 12v tube mod, sockets that go in littledot left and right channel ,do pins 6and 7 have to be cut like in the 6v tube mod.Thanks 

post #3573 of 7352
Quote:
Originally Posted by Artsi View Post
 

I added some paint to my "little box". It does not look so much prototype anymore.

700

 

Using an adapter box such as this is the way all of us should be rolling double triodes in our Little Dots. However, exactly how one goes about making such a box is a mystery to most of us. Speaking for myself, I understand very well what needs to be done and it seems simple enough. However, I have no experience in designing and building something like this. I am hopeful that before too long, we will have available to everyone on this forum a parts list and detailed instructions to enable each of us to build a suitable adapter.

 

Yes, we could keep on mangling pins and cramming 6DJ8 tubes into 7-pin adapters, but this is not optimal (and it won't work at all for the 12-volt double triodes). On several occasions, I have had glass chips break off at the base as a result of bending the pins. And in one case, a crack developed rendering the tube useless. If I could be content to stay with the 6-volt double triodes, and continue to be a "bottom feeder", buying only the cheapest tubes, this is perhaps tolerable. However, I cannot be so content... lol I would really like to try some premium 6DJ8s, but the risk of breaking a tube is too great. And in order to try the 12-volt double triodes, I need a different adapter altogether.

 

So I am hoping that someone who possesses the necessary knowledge and experience will step forward and provide a detailed step-by-step process to enable us to build such an adapter. In the meantime, I have decided to get something like this:

 

9-pin breadboard / prototype tube socket for DIY experimenting

 

$(KGrHqFHJBkE8f)45CEcBPObYIJ3+!~~60_35.JPG

 

This will allow me to make solderless connections to the tube, using the screw / compression terminal blocks. All I have to do is stick the wires in and tighten the screw. And then, I can connect the other ends of the wires to the proper pins in my 7-pin test sockets. I figure it will buy me some time until I can figure out how to make something a bit more functional and elegant like Artsi's "magic" box. :)

post #3574 of 7352
Quote:
Originally Posted by MIKELAP View Post
 

About 12v tube mod, sockets that go in littledot left and right channel ,do pins 6and 7 have to be cut like in the 6v tube mod.Thanks 

 

My understanding is that we cannot run 12-volt double triodes in our current 6-volt adapters. We need something different that will split the 12-volt supply into two 6-volt supplies, one for each triode.... (>_<)

post #3575 of 7352

With my "little box" i used 2 broken tube bottoms as a connection to amp. Those bottoms are glued tightly with epoxy to box. I do not suggest doing this way. Those little wires inside the tubes are pain in the ass to solder with any good connection. I left all pins there, but only needed ones are connected. Box is more steady with more pins. I earlier wrote the list how to connect each pin to B9A socket and heater pins from left channel B7G 3 and 4 go through the switch to B9A pins 4, 5 and 9.

 

12v heater works the way, that you connect B7G pin 3 to B9A pin 9 and B7G pin 4 to both B9A pin 4 and 5.

post #3576 of 7352

Well, at least one thing is for sure now: the bandwagon is on fire!

 

I'm surprised at all the brand new innovative solutions to use double triodes that just popped up here over a few days! Then again, anyone who's tried a few of the tubes recommended here a few weeks ago and then some nice double triodes might feel like he just heard god, so I do understand the sudden passion lol.

 

Still, I'm left wondering which strategy I should adopt as far as adapting those tubes goes...

 

12V center tappable tubes would be good candidates for using a -double- tube for each channel, but after doing a bit (actually a lot) of ebay browsing, I've decided that I'd rather get the best even it means both channels have to share one tube because the best is just that expensive. Besides, the tubes, while easy adaptable to a single channel use, do require some major work to do so (moreso than a 6DJ8 tube).

 

"Regular" 6V double triodes, on the other hand, just aren't meant to be used partially; and as gibosi so clearly worded it, those tubes are just too precious (read expensive) to be mangled and slowly poisoned that way. My own "ram that son of a tube in a B7G socket, bend his arms and strap its legs" idea was just meant as a temporary solution to get people on the bandwagon lol. So single tubes would be the way to go for these types. Btw, have we reached any kind of conclusion on not grounding the shield (pin 9) on the 6DJ8? While it seems like good practice to ground it to get less crosstalk/noise/issues, the internet tells many a story of people not caring at all, which leaves me wondering...

 

I haven't actually tested (or bought) a single 6DJ8 tube yet, just my EI Yugo pairs, so I don't know how they behave with nothing to "isolate" both triodes from each other. 12Ax7 tubes behave perfectly fine used for both sockets; then again, they don't even have a separating shield anyway...

post #3577 of 7352
Quote:
Originally Posted by Artsi View Post
 

With my "little box" i used 2 broken tube bottoms as a connection to amp. Those bottoms are glued tightly with epoxy to box. I do not suggest doing this way. Those little wires inside the tubes are pain in the ass to solder with any good connection. I left all pins there, but only needed ones are connected. Box is more steady with more pins. I earlier wrote the list how to connect each pin to B9A socket and heater pins from left channel B7G 3 and 4 go through the switch to B9A pins 4, 5 and 9.

 

12v heater works the way, that you connect B7G pin 3 to B9A pin 9 and B7G pin 4 to both B9A pin 4 and 5.

 

I believe your explanations have been excellent for those who are comfortable constructing electrical projects. :)

 

But for many of the rest of us, we need a process that is simple enough that our "grandmothers" could do it. lol.  

 

For example, how to we build the box? Is is possible or practical to use a pre-made aluminum or plastic electrical instrument case? But if so, how do we cut the holes? Or perhaps a simple wood box might be the easiest?

 

And then, since using broken tube bases might not be optimal, it seems to me that we need to figure out how to securely connect two un-modified 7-pin socket adapters (I am thinking of the 7-pin Vector socket adapters with test points) to the bottom of the case. Again, I have no experience with projects like this. I can kind of imagine how it might be done, but I don't know how practical or safe my ideas might be.....

post #3578 of 7352
Quote:
Originally Posted by gibosi View Post
 

 

I believe your explanations have been excellent for those who are comfortable constructing electrical projects. :)

 

But for many of the rest of us, we need a process that is simple enough that our "grandmothers" could do it. lol.  

 

For example, how to we build the box? Is is possible or practical to use a pre-made aluminum or plastic electrical instrument case? But if so, how do we cut the holes? Or perhaps a simple wood box might be the easiest?

 

And then, since using broken tube bases might not be optimal, it seems to me that we need to figure out how to securely connect two un-modified 7-pin socket adapters (I am thinking of the 7-pin Vector socket adapters with test points) to the bottom of the case. Again, I have no experience with projects like this. I can kind of imagine how it might be done, but I don't know how practical or safe my ideas might be.....

 

Silly late night (where I live anyway) idea, but instead of using ugly and hard-to-solder-on B7G broken tube bases (which has been my main future hypothesis to make an adapter for a while now; I've actually have two random tubes sitting on my desk for 6 months just because they have thick inner wires that I thought I could eventually solder on to make B7G adapters), you could just dismantle two Vector socket testers (yes, a waste, I know). Let me explain:

 

Take your Vectors apart, find two 7-pin pin savers (like the ones that come with NOS UK tubes), put the pins of your dismantled Vector in one of the pin savers with enough length to make the underside (pin length sticking out of the pin saver) look like a regular B7G tube base. Following me? Well, you're luckier than I am; I'm kind of lost and just throwing this out there lol.

 

Solidify your "pseudo B7G bases) with epoxy or hot glue, and then chop off the length of pin metal you'll need to solder on the upper side of the pseudo-bases. You should get something that looks like a broken B7G tube base but that isn't: it's a clean looking, solid, B7G base with thick metal posts sticking upwards that you should be able to solder on.

 

I haven't figured the rest out yet; like I said, I'm just throwing some nightly ideas here...

 

Of course, one could imagine not killing a hard-to-find B7G socket saver, and scavenging pins from elsewhere, but that's an other adventure altogether.

 

Edit: Extra thought. Vectors may not be completely lost in the process; you could always use the remaining top part and pin length just like before, but without the bottom part... So you'd have a half height socket saver with visible pins, basically (an other pair of pin savers could be used just to make sure the pins actually go straight into a B7G socket and not all over the place. Sorry if I've confused anyone, I'll probably clarify this this weekend after further daytime thinking.


Edited by Audiofanboy - 10/18/13 at 4:49pm
post #3579 of 7352
Quote:
Originally Posted by Audiofanboy View Post
 

.......Btw, have we reached any kind of conclusion on not grounding the shield (pin 9) on the 6DJ8? While it seems like good practice to ground it to get less crosstalk/noise/issues, the internet tells many a story of people not caring at all, which leaves me wondering...

 

 

Using one tube crammed into a 7-pin socket adapter with wires connected to another adapter in the adjacent socket, ground hum is a major problem for me. However, it does not always occur. Perhaps 90% of the time, I get ground hum, but on a few occasions, it has worked perfectly. On the other hand, Artsi reports that grounding pin 9 has not been necessary with his magic box. So perhaps the ground hum problem I am having is related to using a 7-pin adapter with flying pins. Once I get the 9-pin socket mounted on a breadboard I have ordered, I should be able to test this further....

 

Also, I think your idea of using modified Vector adapters with pin savers would work quite nicely. However, I am still stuck at step number one, trying to figure out how to make an enclosure. I plan to go to a hobby shop today to look around....

post #3580 of 7352

I made new THE PRO BOX adapter. I bought made in Canada electric box for it. I took some photos how to make such a thing. This box could be opened afterwards since it is assembled together with 4 screws.

700

Here are the most of things you need to make it. 1mm (18gauge) thick copperwire for the pins is covered with lacquer, so it need to be removed first by grinding.

700

Here are the parts for the pins. B7G socket is just to keep pins more straight when gel super glueing pins through pin protector/straightener. I grind wire head more round.

400

Here it is waiting drying.

700

I made holes to bottom of the box. Paper is there protecting little dot from getting any epoxy. You just push pins through paper. I glued parts together with epoxy.

700

This show the extra wires for the switch.

700

And how the switch is connected to the B9A socket.

700

Soldered all rest wires. Cutted those additional copper wires shorter after taking photo.

700

And here is ready to use product.

 

Sharp-eyed can see that i connected heating from both channels. I measured that they are connected anyway inside little dot. So i think with double wiring i can use up to 0.9A heater current.

 

First wooden box with crappy tube bottoms had very little humming in the right channel with ecc83 tube. It was so little that needed completely silence to notice. Now all humming is gone. I think that there is no need for any kind grounding to pin9 for 6V tubes. Stereo imaging and channel separation is excellent for my hearing.

 

Enjoy! :-)

 

Edit: Box type is 1591MSBK from hammond manufacturing.


Edited by Artsi - 10/19/13 at 7:27am
post #3581 of 7352
Quote:
Originally Posted by Artsi View Post
 

First wooden box with crappy tube bottoms had very little humming in the right channel with ecc83 tube. It was so little that needed completely silence to notice. Now all humming is gone. I think that there is no need for any kind grounding to pin9 for 6V tubes. Stereo imaging and channel separation is excellent for my hearing.

 

Enjoy! :-)

 

Great stuff Artsi! Of course, I can't really make a converter box on my amp (MK IV SE) since I have those brass tube protectors... So, I might have to keep using some hybrid strategy in my case. I could probably hide the wires at least though.

 

So wait, you got hum using a single 12AX7/ECC83? That's odd, since I have had no problem whatsoever with those tube types yet, even connected in very temporary and dangerous ways...!

 

I really can't see why there would be a "ground" problem with these tubes though, they don't even have a shield ...

 

Even for ECC88/6DJ8 tubes, I agree that grounding pin 9 or not shouldn't make a difference as far as a "ground hum" is concerned. It should only isolate the two triodes from each others' effects basically. Why only one side of these tubes would hum seems odd to me... Unless the wiring is bad or picking up somekind of intereference or signal or something? Gibosi, when you tried using a single 6DJ8 tubes rammed in one socket and with wires flying to a socket adapter in the other socket, do you get a hum on the other channel when you invert the whole structure? Do you get a hum using a 6DJ8 tube "in the middle", as in with wires connected it to each side? I'm about to buy a premium single 6DJ8 tube, so I'm obviously very interested in the latest developments on this matter lol.

 

And yes, surprisingly, I find that channel separation and imaging is much better on these "double" tubes than using any single tube I've tested!

post #3582 of 7352
Quote:
Originally Posted by Audiofanboy View Post
 

 

So wait, you got hum using a single 12AX7/ECC83? That's odd, since I have had no problem whatsoever with those tube types yet, even connected in very temporary and dangerous ways...!

 

I really can't see why there would be a "ground" problem with these tubes though, they don't even have a shield ...

 

Even for ECC88/6DJ8 tubes, I agree that grounding pin 9 or not shouldn't make a difference as far as a "ground hum" is concerned. It should only isolate the two triodes from each others' effects basically. Why only one side of these tubes would hum seems odd to me... Unless the wiring is bad or picking up somekind of intereference or signal or something?

 

There was this little humming with that prototype-box. It could be some interference from somewhere and/or bad connection. And i could not repair it as it was filled with epoxy.

post #3583 of 7352
Most excellent work Artsi, a job well done for sure!
beerchug.gif
post #3584 of 7352

1000

Now this is something. Using 3x 6N6P-IR tubes at once! Works with no problems.

 

btw 6N6P-IR as a driver seems to be my first even little microphonic double triode tube... I can hear some noise if i touch tube or knock it with finger nail.


Edited by Artsi - 10/19/13 at 8:29am
post #3585 of 7352
Quote:
Originally Posted by Artsi View Post
 

Now this is something. Using 3x 6N6P-IR tubes at once! Works with no problems.

 

btw 6N6P-IR as a driver seems to be my first even little microphonic double triode tube... I can hear some noise if i touch tube or knock it with finger nail.

 

Funny, I thought about trying the same trick with 6N30P-DR tubes, but ended up not because mu would be a little on the low side for driver tubes, and gm would be over the roof (it's already quite high with 6DJ8 tubes)!

 

How does it sound though, good?

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