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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 83

post #1231 of 6812
Quote:
Originally Posted by Johnnysound View Post

Thanks gibosi. In the end the most practical solution for swapping tubes are the custom adaptors you are looking for.  The chinese can make them for sure...it they see a market.    Please let me know about previous posts, some kind of "guide" regarding tubes requiring 2-7 or 5-7 strapping.  I understand it is a way of using the LDMKIII  default   EF95 setting with many different tubes.     

Acapella11 has put together a chart with exactly the information you are looking for. Please see post 1154 on page 77.

post #1232 of 6812

Recently, I have been listening exclusively to mutilated triodes, namely Sylvania 6AV6 and Sylvania 8532W/6J4. Both of these are very fine tubes, but the 8532 is a bit darker than the 6AV6.

 

Hey, it feels rather lonely here in mutilated triode land!! Is anyone else listening to triodes????

 

In the meantime, several more triodes have shown up in my mailbox:

 

The CV5311, Mullards version of the 8532W/6J4.

 

 

 

Mullard 6VA6. It is interesting that there is no Mullard shield printed on this tube. Moreover, the European designation, EBC91 is not printed on the tube. I wonder if these might have been manufactured exclusively for the American market?

 

 

GE 6AV6 rebranded as EICO

 

 

And I often see mentioned that RCA black plate 12AX7s are some of the best. So I thought why not get some RCA black plate 6AV6?

 

 

And finally, a bit of a teaser... Audiofanboy thinks the 6AQ4/EC91 triode is worth checking out.....

 

post #1233 of 6812
Quote:
Originally Posted by Johnnysound View Post

HI Hypnos1,  and many thanks for the tip, the TS 6485 are on its way (5 units for 15.99) looks like a really good price.  I do not live in the U.S., (Lima, Peru)  but a friend is coming in a few days.   You just do not find tubes here so easily, but looking really hard around old electronics stores you can find really nice NOS tubes at bargain prices ¡¡  What I will do with the tubes is to bring them to a veteran technician who happens to (still) have a tube tester, and ask him to select a "matched pair" from the five units.  Second, I will ask the man to test the tubes at full operational temperature for microphonics.  Then, I will have a "selected" pair of TS 6485.  Next step should be to solder a tiny, 30 awg solid wire between pins 2-7.  I agree with others in this forum that this is the best solution.  I know how to solder  and believe me, "clean" pins is not enough. You have to work very carefully the surface of the pins for a good solder joint, and it means completely removing the plating metal in that area. Second, the tips of the wire should be lightly "tinned" of course. Third, you have to apply just a tiny quantity of solder for a good joint, without compromising the pins connection.  All that in a very small space. It will not be easy, but I think I can do it.  Sorry about my ignorance, but I understand the 6485 is an EF95 tube, so I do not need to change any jumper settings, right ? 

 

BTW, the Voshkods are near full burn in now, and I am  really impressed.  The sound is way better now.  Gone are my feelings about a problem in the mids.  The bass was excellent but now is just outstanding, deep, tight, precise.  The highs are super extended,  but perhaps the top advantage  of this tube is not in some particular areas but in its big, dynamic, transparent sound.  It is kind of ruthless.  With some kind of music,  or better said, with some not-so-good recordings (compressed or over equalised) the Voshkods may hit too hard,  but with good material they can sound positively heavenly  If you know what I mean. However, the pair I have become  kind of mildly microphonic at full temperature, and that bothers me a lot at very low volumes. Curiously, the effect  is not that significant  with headphones, but my recent testing was done with the LD MKIII as a preamp directly into two mono, 250 W SS NAD amps, with my big DCM bi amped towers and I can tell you this is a hard  test for tubes.  Of course headphones are much more revealing and transparent,  but in terms of soundstage, bass and dynamics  here you have  a room to fill, and in this "real world" situation the Voshkods simply sounded superior to the other two or three tubes I have.  As you can see, this will be a nice test for the 6485's.  I´ll let you know...kind regards,                        

Hi J,

 

Glad you were able to source the 6485s at such a good price - and to have someone match a pair is even better!

I cannot wait until you try them, given your findings re the Voskhods...mine have done about 50 hours now, and combined with about 40 hours on a pair of early 6N30P-DRs I cannot believe what my ears  - and brain - are experiencing. I can only hope your setup (and you!) are  treated to something similar...

 

Thanks to Gibosi for the info re EF95 setting.

 

Your comments re soldering were interesting - just might have a go sometime. Methinks the complex alloys used in the pins - possibly manganese/zinc/nickel/copper/cobalt - would contribute to the very careful preparation needed before getting anywhere near with the iron. I, and others on this forum I am sure, look forward to your outcomes in this feat!

 

Regards, CJ


Edited by hypnos1 - 5/13/13 at 12:02pm
post #1234 of 6812

Hi Gibosi,

 

Yes, I have also been investigating the modified triode tubes 6AV6 and 8532. (Let's stick to calling them modified tubes rather than mutilated tubes; sounds much better, doesn't it?)

 

Finally got four different 6AV6 tubes: Two sidegetter Sylvania and RCA, a 50's-60's Tung Sol and a late 70's-80's Sylvania/Phillips. I assume that the side getter tubes are the oldest. Not one tube is identical to the other as far as the internals go. In addition one Sylvania 8532 tube that has a completely different construction.

From right to left: RCA with side getter with silver plate; 50's- 60's Tung Sol, late model Sylvania-Phillips with curious small ring attached to the Gray plate {don't forget to double click picture to get a full view}, older Sylvania side getter, and the 1970 Sylvania 8532.

"Band-aid" view. Agree with Inphu510n that it feels strange to render the tubes unusable for others. This will explain why I only got one of each - they were all less than $2.50 including shipping. I figured I'll try them out, A/B them on a good mono recording, and I would find out what I like the best.

 

 

First I printed out pictures of post surgery tubes from the blog, as well as the pin charts. Then I marked the pins to cut off with a black marking pen. Used a small jeweler's cutter, took a deep breath and squeezed. I heard the cut off pin land somewhere on my cluttered desk - wasn't too hard to cut the pin. Little stumps were left (think beaver) and I was able to take off a little more with the cutter. (My retired engineer friend had told me not to file the excess down because I might damage the vacuum seal.) Then I took electric tape and cut a tapered piece so that it is smaller between the pins and bigger outside the pin perimeter for better adhesion.

Success!

Heavily perspiring I grabbed my tweezers and pulled out the pesky jumpers, using a flashlight to see inside. Managed to get them back in the E92 position without bending the pins inside the LD.

 

Also got a pair of RCA 6BY6 heptodes from Oct 1966. (I anybody is interested, I could post a RCA code chart from 1956-1976.) Convenient to listen to these as well, as they use the EF92 setting.

 

With all this sensory overload it will take a little time to sort out the winners and losers. Truth is, most of the new tubes have been very nice, heads and shoulders over the traditional tubes.

 

Then, when I have picket a winner (or several), I am going to do a shoot out with the EF95 strap 2&7 setting on one channel and the EF92 setting on the other channel to compare the 6AH6/6AU6/4825 to the triode-heptode families. -Better get a good night's sleep before so that I don't make any mistakes in rigging it up!

post #1235 of 6812

I got response from the guy regarding the socket adaptor he says they can do the adaptor but before i order i want to make shure that the o.d. of the socket fis in th mk3 hole anyway heres his message                                           Hello,


Sorry, yesterday we were on holiday, we can made the 7 pins to 7 pins adapters for you, price is: 16.5 dollars, shipping cost for 1-4 pcs is: 5 dollars,

How many pcs would you like to buy?

Thanks&Best Regards,
Vanessa
 

- happydiy998
post #1236 of 6812
Quote:
Originally Posted by mordy View Post

..........I only got one of each - they were all less than $2.50 including shipping. I figured I'll try them out, A/B them on a good mono recording, and I would find out what I like the best.

 

Then, when I have picket a winner (or several), I am going to do a shoot out with the EF95 strap 2&7 setting on one channel and the EF92 setting on the other channel to compare the 6AH6/6AU6/4825 to the triode-heptode families. -Better get a good night's sleep before so that I don't make any mistakes in rigging it up!

 

It's nice to know that someone else is finally listening to triodes. And I must say you have a very efficient and cost-effective way to evaluating tubes!

 

As we have three in common, Sylvania 8532, and Sylvania and RCA 6AV6 with side-getters, I will be very interested in your impressions of these three. I tried to find a nice pair of Tung-Sol 6AV6 with no luck, and will also be very interested in what you think of it.

 

Good luck to you as you embark on your tube marathon! :) 

post #1237 of 6812
Quote:
Originally Posted by hypnos1 View Post

Your comments re soldering were interesting - just might have a go sometime. Methinks the complex alloys used in the pins - possibly manganese/zinc/copper/cobalt - would contribute to the very careful preparation needed before getting anywhere near with the iron. I, and others on this forum I am sure, look forward to your outcomes in this feat!

 

 

Inphu510n has successfully soldered pins 2 and 7 together (post #1026 page 69). If you encounter any problems, you might want to contact him for his advice.

post #1238 of 6812
Quote:
Originally Posted by gibosi View Post

 

It's nice to know that someone else is finally listening to triodes. And I must say you have a very efficient and cost-effective way to evaluating tubes!

 

As we have three in common, Sylvania 8532, and Sylvania and RCA 6AV6 with side-getters, I will be very interested in your impressions of these three. I tried to find a nice pair of Tung-Sol 6AV6 with no luck, and will also be very interested in what you think of it.

 

Good luck to you as you embark on your tube marathon! :) 

www.tubebazar.com         I checked my guy site these are the 6av6 he has.  Tun-sol i dont know youll have to check.                           

6AV6 REF: EBC91 Yes / Oui
6AV6 / EBC91 Yes / Oui
6AV6 - F4A Yes / Oui
6AV6 - F8 Yes / Oui
6AV6 - H5 Yes / Oui
post #1239 of 6812

Thanks for the pointer. However, I think I will hold off on the Tung-Sols until we have Mordy's impressions. Besides, I have the 5 pairs of triodes above to butcher and burnin, plus I have a few more triodes coming, so buying more tubes is the very last thing I should be doing. lol

 

This morning I butchered the RCA 6AV6 and they have been burning in for about 10 hours now. First impressions, these are good sounding tubes....

post #1240 of 6812

Hi Gibosi,

 

LOL, firstly, let's keep up the high ethical standards of this forum dt880smile.png and not amputate or butcher tubes, just modify them for our needs.

 

To evaluate 5 new tubes takes a lot of mental energy, so I temporarily put aside this project in favor of evaluating a pair of RCA 6BY6 heptodes, which is an easier mental challenge. (Paid $5.25 total incl. shipping from a nice seller.) These only require the EF92 setting and nothing else (Plug and Play?).

 

At first I was not impressed by them. Nothing objectionable in the sound, but the treble was too bright and a little sibilant, and the bass was not very deep and a little weak. The mid range was pretty good but I thought that these tubes are not any better than a good 6AK5 tube.

 

However, you have to take your own advice and be patient. Tubes need to burn in, usually a minimum of 20 hours and some 50 hours (Voskhods need 120 hours). So I stuck in the 6BY6 tubes and left my system on, on low volume. These tubes do not get very hot, and I can easily touch them without worry.

 

{About my own advice: If you have trouble with a tube quitting on you suddenly, scrape the pins gently to get off the oxidation. I was going to practice cutting off the pins for the triodes, but could not think of a defective tube to cut. Then I remembered that one of the original LD 6N6P-i power tubes had stopped working. For some reason I had saved it around two years. Well, before doing the surgery I looked it over, looking at the pins. One pin looked greenish. Out came the pocket knife. Plugged in the tube. What??? It is working!! Couldn't believe it....}

 

Well, after supper I couldn't believe this either! The 6BY6 tubes had suddenly come to life after about 25 hours of use! The sound stage suddenly became huge with sound emanating from outside of the speakers on some recordings. The bass became much stronger. The mid range is sweet. The treble is still too bright, but can easily be adjusted with my tone control. I am hearing the same type of magic as from the 6AH6/6AU6 tubes. Not as detailed, not the same pin point imaging and clarity, but nevertheless a sweet, warm and engaging (tubey?) sound.

 

I feel that these still need more time - will keep you posted.

post #1241 of 6812

So its a go for the sockets there suppose to fit the littledot mk3 the price is $16.50 each plus $5.00 shipping for up to 4 pieces . I ordered 2 so we will see what happens they will ship in a couple of days and i hope its faster from China that it was from Russia if you recall (1month).in the meantime im expecting my 6AU6 AND 6BE6 tubes in a few days ,seller infos :                         happydiy998     

post #1242 of 6812

Mikelap,

 

This is great news! And I sure hope that they don't take too long, but from their website, it could take up to 40 days....  On the other hand, some small stranded wire will suffice until they finally arrive.

 

I have decided to take my socket testers to a jeweler to see if he would be willing to solder some connections for me. As cheap as these were, $7 each, I ended up purchasing 6 of these, one pair for pins 2 and 7, a second pair for pins 5 and 7, and the third pair will remain stock in case I need something different later. I figure jewelers are very proficient doing intricate work with small pieces of wire, so this should be very easy for them. I hope...

 

In the meantime, I "modified" a pair of Mullard 6AV6 (I still think "butchered" and "mutilated" convey a more honest and accurate description of what we are actually doing to these tubes! :) and they are currently burning in. These too sound very promising. If it turns out that you end up having to wait some 40 days for theses adapters, I would encourage you to pick up a few triodes. I think you will be very pleased with what you hear.... and besides butchering and mutilating tubes is fun! 

post #1243 of 6812

My dremel is itching to cut something and besides my wife calls me Mr. Mod because being an ex machinist i cant leave anything alone gotta mod it i have to read up on the thread to see which tubes you guys MODIFIED or maybe you can give these tired eyes a break and give me the tube numbers you guys are OPERATING  on . Thanks guys.

post #1244 of 6812

We are "operating" on 6AQ6, 6AT6 and 6AV6 (from the same manufacturer these three are typically very similar) and the 6J4/8532W/CV5311. You could try a cheap pair of 6J4 first and then pick up a pair of 8532W and/or CV5311, if you like them.

 

Just cut off pins 5 and 6 (check out my post #1066 on page 72) and use the EF92 jumpers. I initially used my dremel to do this, but using flush cutters (post #1021 page 69) is much, much easier and safer (for the tube).

post #1245 of 6812
Quote:
Originally Posted by gibosi View Post

We are "operating" on 6AQ6, 6AT6 and 6AV6 (from the same manufacturer these three are typically very similar) and the 6J4/8532W/CV5311. You could try a cheap pair of 6J4 first and then pick up a pair of 8532W and/or CV5311, if you like them.

 

Just cut off pins 5 and 6 (check out my post #1066 on page 72) and use the EF92 jumpers. I initially used my dremel to do this, but using flush cutters (post #1021 page 69) is much, much easier and safer (for the tube).

Your so kind thanks a bunch.

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