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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 220

post #3286 of 10486
Quote:
Originally Posted by MIKELAP View Post
 

Got my socket today looks like its not going to be easy to solder the wires because you cannot remove the top part from the housing completely whithout the pins coming out of the housing plus my wire is 22 gauge will see if its small enough .Thats all the space i have to work with 5/16 wide 

 

 

You can just pull the pins out of the housing; it'll be virtually impossible to do anything otherwise. The pins are annoying to put back in their holes afterwards, especially if you try to force them in holding the top part, but they end up going back in fairly easily if you just put them back in their housing and "wiggle" the whole adapter until they go in. The pins eventually go back in their holes that way, or so I've found.

 

If anything, I find that the screw that holds the whole assembly together is problematic. Every time I take the adapter apart, the screw never goes straight in its hole, and gets stuck sideways...

 

On a lighter note, I made a better adapter to use a single 12Ax7 tube as a driver, using two of these brown socket savers/testers and some wire (too short this time, unlike my original "flying" tube experiment). It worked like a charm until I started loosing sound in one channel for half a second every five minutes, and the also in the other channel eventually... I thought the wiring was bad, but I triple checked it, so I have to assume that the tube might be a bit dodgy (I salvaged it from a stack of random tubes I paid 99 pence for, and the only other valuable tube in that stash turned out to be a dud as well, so hardly surprising).

 

Guess I need to find more 12AT7/ECC81 & 12AX7/ECC83 now huh?

post #3287 of 10486

Sorry these totally slipped by...

 

Quote:

Originally Posted by mab1376 View Post
 

 

Nice job! I was looking for something like that, didn't have any hum with my HFI-780's or Pro900's though.

Thanks mab1376!

I didn't have a hum in the beginning with the 5654's, I'll have to put them back in and see. 

Quote:
Originally Posted by Acapella11 View Post
 

 

Great DIY stuff Trolldragon. If you open up an online store, we might get more in touch. ;)

Thanks A11!

My stuff is strictly amateur, I made a free novelty interconnect for a young Head-Fi'er in another thread and it stopped working within a week, told him to be careful with it as it lacked strain relief.

I'm not by any means saying he was rough on it, but that made me realize in order to sell a product, the product has to be a lot sturdier than the ones i make for myself... :D 

People seem to have this burning desire to yank things out by the cord and and even carry them by the cord.

 

But If I do, I'll be sure to let you all know! :wink_face:

post #3288 of 10486

Hi AFB,

 

Can you explain to me what you gain by using one tube 12AT7 in the LD MKIII compared to using one pair of 6AV6 that are said to be one half of the 12AT7?

post #3289 of 10486
Quote:
Originally Posted by MIKELAP View Post
 

Got my socket today looks like its not going to be easy to solder the wires because you cannot remove the top part from the housing completely whithout the pins coming out of the housing plus my wire is 22 gauge will see if its small enough .Thats all the space i have to work with 5/16 wide 

 

There is absolutely nothing more entertaining and invigorating than a chummy that requires 12 fingers to put it back together after you take the screw out. :D

post #3290 of 10486
Quote:
Originally Posted by TrollDragon View Post
 

There is absolutely nothing more entertaining and invigorating than a chummy that requires 12 fingers to put it back together after you take the screw out. :D

screwActually i was really lucky putting the pins back in took me less than 5 minutes using a tooth pick but i was lucky afterwards putting the srcew i dropped the d....m screw took me 15 minutes to find it .Not starting out good and  i didnt even start soldering yet lol

post #3291 of 10486

HI mab 1376,

 

 

Re the 6AV6, it appears that the only good ones are the ones with the box on top of the top mica. Are your tubes made in this way? (Would not worry if the plate has a pointy notch or not - does not seem to matter.)

 

Just finished burning in a pair of Sylvania box top side getter 6AV6. These tubes sound absolutely fantastic in my system, maybe even better than the RCAs I have (lollipop getter, sunglasses look).

 

Specifically, the Syls have a meaty, juicy detailed bass, great mid range and excellent treble. In addition they are very engaging with a TT index of 5.

 

Here are a few pictures of these tubes.

Picture showing the logo (stylized oak leaf) and construction of the tube. Notice the little disc on top.

I have three of these tubes. When I burned them in I did not realize that the little disc on top was bigger on one tube. However, they sound the same, and the third tube matches the one with the smaller disc.

Notice the box on the mica. It has notches in it, but the the third tube with the small disc does not have those notches.

Here you can see the difference in size of the dish antenna on top.

 

Bottom line: These are my favorites now.

post #3292 of 10486
Quote:
Originally Posted by mordy View Post

Hi AFB,

Can you explain to me what you gain by using one tube 12AT7 in the LD MKIII compared to using one pair of 6AV6 that are said to be one half of the 12AT7?

Simple. There evidently is more variety and latent sound quality to be found in the 12Ax7 tubes than in the 6AV6 family, where we've been kind of finding out that there's only half a dozen tube constructions -like those "box" getter tubes- and basically not that much to select from, even though the tubes are cheap.

Also, there is 1000 times more information out there on 12Ax7 and 6DJ8 tubes -hence the crazy prices- which makes it so much more easy to find good tubes for those types; even though we may not be able to actually afford them lol...
post #3293 of 10486

Hi AFB,

 

Thanks for your answer. I am awaiting a comparison of the sound of a favored 12AT7 with the best of the 6AV6 tubes.

 

The other thing that I would like is a detailed step by step guide with pictures how to connect these tubes, which adapters to use, which wires to solder where etc. Perhaps this information can be gleaned from various posts, but it is not very clear to me. It also seems that the simplest and best ways of doing this is still a project in the making.

 

And thanks for all your pioneering work in enhancing the listening experience using the LD MKIII!

post #3294 of 10486

 

Westinghouse 6AV6 -91 made in japan. Shortly: Great sound, with excellent analytics, and/but dryness.

 

Especially with bass you do just what you told to do just like in army. Headphone speaker does not do any more movements than music says. Some people like this and some like more softened sound.

 

 

Edit: did not mean this "dryness" straight as negative thing. It just made me smiling to hear such preciseness in every bass impact and vibration.


Edited by Artsi - 10/4/13 at 12:35pm
post #3295 of 10486

Hi Artsi,

 

Don't know how long you have used your Westinghouse 6AV6 tubes, but I have not come across a tube that changes more after 40-50 hours burn in, all for the positive. I have a feeling that if you give them a chance, they will improve in all aspects. With the ones I have tried, all the things that I did not like "burned" away....

post #3296 of 10486
Quote:
Originally Posted by mordy View Post
 

Hi AFB,

 

Thanks for your answer. I am awaiting a comparison of the sound of a favored 12AT7 with the best of the 6AV6 tubes.

 

The other thing that I would like is a detailed step by step guide with pictures how to connect these tubes, which adapters to use, which wires to solder where etc. Perhaps this information can be gleaned from various posts, but it is not very clear to me. It also seems that the simplest and best ways of doing this is still a project in the making.

 

And thanks for all your pioneering work in enhancing the listening experience using the LD MKIII!

Looks like theres 2 mods  one is this by AFB :

Yes, basically you are trying to use only the first triode in the tube, so all the leftover pins need to be neutralized or at least out of the way. So, pins 1, 2, 3 & 9 of the 6BQ7A need to be bent or cut, while pins 4, 5, 6, 7 & 8 can be inserted in a sequence into the socket hole 3, 4, 5, 6 & 7 of your adapter. Next, you just have to link/solder pin 6 to pin 1, and pin 7 to pin 2 on the adapter (with pins 6 & 7 disconnected at the base), and voila! You get a single 7-pin triode!

 

Gibosi actually summed it up better than I can in his post:

 

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/3145

And on post #3145 at the bottom gibosi speaks of a wiring harness that is linked to another socket with no tube this mod using the 2 triodes of the tube instead of one if i am not mistaken in the first mod. One thing thats not clear in 2nd mod  is the ground part is that settled ? Thats what i think i know am i correct ? A complete procedure would be great in time when everything is settled and clear.


Edited by MIKELAP - 10/4/13 at 12:43pm
post #3297 of 10486

MORDY'S QUICK CHANGE JUMPERS

 

And, now for all of us with fumbly fingers like me, here is another idea of how to make it easy to change those pesky jumpers underneath the LD MKIII amp from EF95 to EF92 and back and forth.

 

First, I raised my amp about an inch by sticking on my 1980s hi fi cones on the bottom of the amp with blue tack (well actually yellow tack from the 99c store).

Raising the amp allows for more heat dissipation through convection, and the pointy cones dissipate unwanted vibrations from wherever. I have no problems with microphonics at all. In truth, anything  to raise it will work - pieces of wood, plastic, whatever.

Next to the front cone you can see a black and white piece of plastic sticking out. Those are the handles to the jumpers.

Here are the jumpers with extensions attached. The extensions were taken from the click mechanism of Uniball gel pens. The jumpers have long handles but I don't know where to get these with a round tail - these came with a solar powered house number set. The long handle jumpers that you can buy probably can be cut to fit inside the hole on the plastic piece.

Here is the jumper with handle detached. It is just a pressure fit to make it stay on.

To change jumpers I tilt the amp left on it's side. EF95 means that the jumper gets pushed into the upper part of the oval hole, EF92 into the bottom of the oval hole. In order to make it easier to see where the jumper goes I use a little LED flashlight.

 

This makes it much easier. Maybe an upgraded MKIII will come with simple switches on the back plate and array of adapters for all kinds of tube types...

post #3298 of 10486
Quote:
Originally Posted by mordy View Post
 

HI mab 1376,

 

Re the 6AV6, it appears that the only good ones are the ones with the box on top of the top mica. Are your tubes made in this way? (Would not worry if the plate has a pointy notch or not - does not seem to matter.)

 

To clarify, so far, all the 6AV6 I have tried with the pointy notched diode plates sound the same. Therefore, the GE, FIVRE, Toshiba and Tung-Sol, all sound like the GE 6AV6. Your experience confirms that RCAs and Sylvanias, with the box, but different style diode plates, also sound very good, but different than the GE.

post #3299 of 10486
Quote:
Originally Posted by MIKELAP View Post
 

Looks like theres 2 mods  one is this by AFB :

Yes, basically you are trying to use only the first triode in the tube, so all the leftover pins need to be neutralized or at least out of the way. So, pins 1, 2, 3 & 9 of the 6BQ7A need to be bent or cut, while pins 4, 5, 6, 7 & 8 can be inserted in a sequence into the socket hole 3, 4, 5, 6 & 7 of your adapter. Next, you just have to link/solder pin 6 to pin 1, and pin 7 to pin 2 on the adapter (with pins 6 & 7 disconnected at the base), and voila! You get a single 7-pin triode!

 

Gibosi actually summed it up better than I can in his post:

 

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/3145

And on post #3145 at the bottom gibosi speaks of a wiring harness that is linked to another socket with no tube this mod using the 2 triodes of the tube instead of one if i am not mistaken in the first mod. One thing thats not clear in 2nd mod  is the ground part is that settled ? Thats what i think i know am i correct ? A complete procedure would be great in time when everything is settled and clear.

 

What does disconnect pins 6 and 7 at the base mean exactly remove them ?And is that at base of socket those are the pins that will go in LD that are cut Thanks.


Edited by MIKELAP - 10/4/13 at 1:28pm
post #3300 of 10486
Quote:
Originally Posted by MIKELAP View Post
 

 

What does disconnect pins 6 and 7 at the base mean exactly .Thanks.

 

Easy, just chop them off! Take your adapters apart, bend pins 6 & 7 at a 90° angle (going towards pins 1 & 2 but not through the center part of the adapter, so you don't block the screw), chop off the part of pins 6 & 7 that goes too far (just leave enough of the pins to make good contact and solder onto pins 1 & 2), and solder bent pins 6 & 7 to pins 1 & 2! Then put the adapter back together.

 

I should have taken pictures of one the adapted adapters, but alas, I never think about doing that when I'm actually making stuff, too much excitement as it is -and I don't like to show my crappy solder work too lol...

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