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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 212

post #3166 of 10504
Quote:
Originally Posted by gibosi View Post
 

 

Up and running in the LD 1+. Except for the fact that they lean - with the bent pins, I can't get them straight - they don't look too bad.... 

 

 

Stupid question : Why dont you just cut them off is it just in case might use them for something else eventually just curious.

post #3167 of 10504

Just got in some new 6AV6 tubes with the rectangular box on top of the top mica. One pair is made by RCA with a peculiar top side getter flash in fashionable dark brown, hereby dubbed the "Sunglass getter flash"  - see picture. The getter looks like a lollipop stick but instead of the top being round it is C shaped (picture 2, 3 and 4). (Lollipop getter)

 

 

 

Got these cheap, and, perhaps because they are sold as used and thus presumably burnt in, they sound great right out of the bubble wrap. Unfortunately, one of the 6AV6 comrades bit the dust due to poor packaging (not the first time) even though I cautioned the seller to pack the tubes carefully in individual pieces of bubble wrap, and then surrounding all the small packages with more bubble wrap or other packaging materials.

 

So what we got? A pair of RCA Sunglass-lollipop tubes that sound fantastic. I have learned to do the 5/6 surgery quickly and painlessly. First I take a 6AV6 tube where the pins have been cut off successfully already and hold it up to the new ones. Then I mark the pins to cut off (#5 and #6) with a black marking pen. After this I take my side cutter and hold the tube over my office (or is it Man Cave) garbage can and snip off the pins. Doesn't matter if there are little stubs left; I just cut off a little V shaped piece of electrical tape and cover the stubs. The extra piece of tape that sticks out is cut off and used as a second layer over the stubs.

 

A second pair of 6AV6 Sylvania was included as well plus one single unknown tube and the GE fatality.Most of the pins were corroded, and I scraped them with my 1949 Colonial pocket knife, and even gave the RCA's the sand bowl treatment.

One of Sylvanias had barely any volume, so I followed my own advice and scraped it again and again. Success! The Syls don't sound as good as the RCAs, but they may need more time to burn in. (Starting to sound better)

 

So many thrills in tube rolling! Bargain hunting, corresponding with the seller about the broken tube, finding new tube designs hitherto not seen in my experience, using high tech and highly advanced pin cleaning techniques, and then rewarded with stupendous sound! Wow!

post #3168 of 10504
I have a pair of the NEC 6AV6's coming on a slow boat from Taiwan...
post #3169 of 10504
Quote:
Originally Posted by MIKELAP View Post

Stupid question : Why dont you just cut them off is it just in case might use them for something else eventually just curious.
This was my thought as well, I think when I scrape up some funds to play dual triode. I'll see about grafting a B9A socket onto a B7G socket saver... biggrin.gif
post #3170 of 10504
Quote:
Originally Posted by gibosi View Post
 

Oh, and make sure there is some slack in the wire as it crosses over the hole for the machine screw. On one adapter, the wire was a bit too tight, and when I tried to insert the machine screw, I broke the wire.... (>_<)

 

 

Yeah... Same exact issue happened to me on my first try: I had soldered the bent pins 6 & 7 to pins 1 & 2 straight across the middle of the adapter and couldn't get the screw to go through the adapter straight -basically couldn't close the adapter back up. I eventually got the screw to go straight through but isolated it from the pins to play it safe.

 

On my second adapter, I bent the pins in a roundabout fashion, but was so focused on that that I soldered the pins the wrong way around... Took me half an hour to get the pins unsoldered...

 

Quote:
Originally Posted by TrollDragon View Post


This was my thought as well, I think when I scrape up some funds to play dual triode. I'll see about grafting a B9A socket onto a B7G socket saver... biggrin.gif

 

My next project, precisely.

 

Will report on how hard/cumbersome/ugly it turns out!

 

I think I'll try and make it "flexible" for my first try. As in, wires soldered to all 9 pins of the B9A socket, but the same wires only tightened onto the adapter and not soldered, so I can play around with different options before settling in on a specific pin layout.

post #3171 of 10504
Excellent AFB, I'll look forward to your findings and creativity. smily_headphones1.gif
post #3172 of 10504
Quote:
Originally Posted by MIKELAP View Post
 

Stupid question : Why dont you just cut them off is it just in case might use them for something else eventually just curious.

 

Not stupid at all! :)

 

Since there is a second triode in these tubes, an "extra" triode, if you will, if I were to cut off the pins, I would no longer be able to gain access to it. Since we are still experimenting to figure out the best ways to use these tubes, I wish to keep my options open.

 

And this is especially true with the "pair" I currently have. The vendor listed these as a pair of Mullards. However, one tube is essentially an Amperex, manufactured in Holland, and the other is a Mullard, manufactred in the UK. So I do not wish to continue using these as a "pair" long term. Therefore, I am interested in using both triodes in each tube per this image originally posted by Oskari:

 

 

I have picked up some parts from a local electronics supply store and intend to make a suitable wiring harness to connect the three bent pins associated with the second triode to a socket adapter installed in the empty socket. Once I get this working (or not), I will post my results with more pictures and info.

post #3173 of 10504
Quote:
Originally Posted by Audiofanboy View Post
 

I might also try and wire a pair for running 6DJ8/ECC88 tubes in parallel; but first I need to figure out how I'm even going to wire the sockets to the adapters... Soldering 9 small wires to each socket just doesn't sound fun...

 

What do you see as the advantages of running these tubes in parallel?

post #3174 of 10504
Quote:
Originally Posted by gibosi View Post
 

 

Not stupid at all! :)

 

Since there is a second triode in these tubes, an "extra" triode, if you will, if I were to cut off the pins, I would no longer be able to gain access to it. Since we are still experimenting to figure out the best ways to use these tubes, I wish to keep my options open.

 

And this is especially true with the "pair" I currently have. The vendor listed these as a pair of Mullards. However, one tube is essentially an Amperex, manufactured in Holland, and the other is a Mullard, manufactred in the UK. So I do not wish to continue using these as a "pair" long term. Therefore, I am interested in using both triodes in each tube per this image originally posted by Oskari:

 

 

I have picked up some parts from a local electronics supply store and intend to make a suitable wiring harness to connect the three bent pins associated with the second triode to a socket adapter installed in the empty socket. Once I get this working (or not), I will post my results with more pictures and info.

 

If i got it right we are only using one of the 2 triodes in the tube.

post #3175 of 10504
Quote:
Originally Posted by MIKELAP View Post
 

If i got it right we are only using one of the 2 triodes in the tube.

 

Yes, you have it exactly right. By bending four pins out of the way (or cutting them off) and then cramming the tube into our 7-pin adapters, we are essentially converting a dual triode into a single triode. But given that these 6FJ8 / ECC88 tubes can be quite expensive, if we could use that second triode, and thus get by with purchasing just one tube, instead of two, our wallets will thank us. :)

post #3176 of 10504
Quote:
Originally Posted by gibosi View Post
 

 

Yes, you have it exactly right. By bending four pins out of the way (or cutting them off) and then cramming the tube into our 7-pin adapters, we are essentially converting a dual triode into a single triode. But given that these 6FJ8 / ECC88 tubes can be quite expensive, if we could use that second triode, and thus get by with purchasing just one tube, instead of two, our wallets will thank us. :)

i also noticed that they were very expensive you mentionned 6BQ7A tubes those are the ones i got by RCA comes out to $5.00 each next up is learning to solder plenty of videos on the tube ill check that out plenty of time to practice .

post #3177 of 10504
Quote:
Originally Posted by MIKELAP View Post
 

...... next up is learning to solder plenty of videos on the tube ill check that out plenty of time to practice .

 

Have fun learning to solder. In my experience, the key to a good electrical solder joint is to make sure you have a good mechanical connection first. Wrap those wires around the adapter pins 2 or 3 times and make sure they are good and tight. If you just touch the wire to the pin and add solder, the joint might end up being pretty bad. Solder on its own is actually a rather poor electrical conductor and its real purpose is to simply ensure that the joint doesn't work loose over time. Good luck! :)

post #3178 of 10504
Also heat the pin / wire with the iron and touch the solder to it, don't just melt the solder with the iron. biggrin.gif
post #3179 of 10504
Quote:
Originally Posted by TrollDragon View Post

I have a pair of the NEC 6AV6's coming on a slow boat from Taiwan...

 

I also ordered pair of those. I think it takes 3 weeks to arrive.

 

6J3P(-E) -84/82 This tube is also what i could recommend. Biggest problem is propably with microphonic. No sound coming through and any touch to amp makes ringing noise, more without -E tube. Ordered two 6J3P and the other one is with -E. Sound seems to be so similar that can't tell any difference with or without -E. Wow-effect is not so strong as with excellent 6J5P, upper range to treble just does not sound so clean. Could microphonic-problem cause some treble-echo...

http://kuvaton.com/k/Y7FI.jpg

 

GE JAN 5654 -69 I have listened these work horses many hours before i got those newer Russian tubes. No, these could not be horses, they are so tiny tubes, that work pony is better. Overall sound is pretty good with little bit of harshness. Bass is somehow little bit quieter and quieten more to sub bass. In comparison with Russian basic military 6J1P -71 IMHO Russia wins hands down.

http://kuvaton.com/k/Y7Fk.jpg

 

Tungsram 6BE6 Manufacturing year is not visible on the tube or on the box. With these soundstage is narrower. Treble has some harshness and bass shares same problems with JAN 5654. Can't describe these better, music just is not so living as with better drivers.

http://kuvaton.com/k/Y7Fi.jpg

 

GE 6AU6A -70 These were used "pulls from equipment". Sound has some cleanliness problems. Singer s sounds very hissing and treble is bit annoying. Only positive thing is pretty good bass.

http://kuvaton.com/k/Y7Fg.jpg

 

Afterall these experiences are made with very analytic slightly modded superlux HD-330 headphones. With smooth and easy sounding, sub bass lacking and dull treble sennheiser HD598 user experience is very different. With senns differences are much more difficult to tell. Comparing with senns GE JAN 5654 and 6J1P could turn that GE sounds better with some sharpness and you can't however hear any sub bass quietness.

post #3180 of 10504
Quote:
Originally Posted by gibosi View Post
 

 

What do you see as the advantages of running these tubes in parallel?

 

Basically, identical gain but higher gm. And theoretically less noise. Of course, it would also solve the unused triode issue...

 

My only worry is that since a 6DJ8/ECC88 has very high gm per triode in the first place, a paralleled one may end up on the high side; and I'm not exactly looking for 20k gm values, I'd rather have higher mu instead. So, if anything, a 12Ax7 tube might be a better candidate for  paralleling (high (12AT7) to very high (12AX7) mu, medium to low gm); but then again, we don't really have that unused triode issue with 12Ax7 tubes since the triodes can be heated separately...

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