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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 311

post #4651 of 10559

In today's mail I received two 6NS7 I have been eagerly anticipating: Tung Sol VT-231/6SN7GT and a Sylvania 6SN7GT "Bad Boy."

 

The 1948 Tung-Sol with round black plates and black smoked glass is labeled Emerson. The vendor seemed not to realize it was a Tung Sol and I was able to get it for around $50.00. While $50 is certainly not cheap, this tube is considered one of the best 6SN7 and usually goes for $100 and up.

 

The Sylvania Bad Boy with 3-hole black T-plates, bottom getter, manufactured in 1952 is another highly ranked tube. I managed to get this tube for around $20.00. As it usually goes for $60 and up, a pretty good deal I think.

 

post #4652 of 10559
Quote:
Originally Posted by mordy View Post

Hi TD,

Any update on the power protection circuit so that you can use the LD amp with DC coupled amps?
Hi mordy!
I just emailed him for a status update. smily_headphones1.gif
post #4653 of 10559

Hey all, I'm new to this forum and to tube amps as well but since you guys have experience poking around inside these amps I figured here would be a good place to start. I got a little dot mkII for Christmas and it has been working for the past month but now it has a strange buzzing sound in the left channel. Even with I unplug all my other components I can still hear the noise. I tried moving around the power tubes and headphone tubes but the sound still stays in the left channel. I was wondering if you guys had any other suggestions on how to make the noise go away so I can enjoy my amp again.

post #4654 of 10559

Well folks, I think I may just have found my endgame tube(s) at long last, and I'm afraid it's ciao to the 6DJ8s - never thought that would happen! Even my beloved Tesla E88ccs (gold pins and grids) have been blown out of the water...by the Siemens C3gs I have finally managed to complete the adapters for - they are an 8-pin pentode (can be triode connected) with different pin-out, of course, to the 6AK5.

 

Apparently they were conceived by some VERY demanding engineers, wanting uber low distortion, microphonics, noise etc etc but with high gain, linearity and very long life. All I can say is they worked miracles, because they have not only filled the slight gaps in the otherwise excellent Teslas, but also surpass them in ALL areas - given my equipment and ears, of course.

 

Bass is phenomenal, in detail and extension (slam is too crude a word to apply to these beauties).

Treble ditto, without the occasional sibilance of the Teslas.

Mids have returned nicely, with no loss in the other frequencies - in fact no range dominates to the detriment of others.

Soundstage is truly remarkable - a magic trick that manages to achieve the 3-dimensionality of the Teslas with even more detail...a rare ability I would suspect.

Imaging is precise, along with instrument and voice positioning/separation. Vocals are slightly more forward than the T's, giving a slightly more intimate musical experience while retaining a fine overall balance.

The tonal range is immense, along with dynamic range - from attack thru decay, instruments are taking on a whole new (magical) persona.

 

And the low noise/high linearity pre-requisites are manifested by the dead silence in a 'black' background, and a deliciously 'clean' sound of wonderful clarity.

 

In other words, I am totally blown away, in case you hadn't guessed!

 

Perhaps my (obsessive) desire to keep to a minimum the number of in-line connections and mix of metals may have also helped somewhat...in line with my previous mods, I decided to use pure silver wire for fitting tube to LD socket - in fact I bit the bullet and did away with an adapter as such and connected (scarily!) 1mm wire direct to the tube pins, said wire also acting as the B7 pins, instead of a cut-away tube base. Sealing things in resin to (hopefully) prevent connections becoming DISconnected meant I only really had one chance to get things right...a bit of a nightmare, to say the least!

Anyway, thankfully all was well (so far) and the final result has proved to be worth every ounce of sweat and nervous exhaustion.

This 'pentode' certainly seems like no other, and would explain Yamamoto's choice of the C3 family for some of his lovely amps...

 

:

 

 

The above, of course, is NOT the right photo -  (don't know how to remove it!). Hopefully second time lucky...

 

That's more like it!!

post #4655 of 10559
Quote:

Originally Posted by hypnos1 

 

 

I'm a little behind on this thread, whats going on with your headphone jack there?

 

also congrats on getting those tubes working! I'm no too handy, but hopefully I can get a change to try them somehow down the road if i can find a pair and build adapters which I'm hoping is in the thread somewhere. I'm still using 6AV6 tubes a pretty pleased with them overall.

 

Also a quick google on that tube shows an "S" versions with tighter specs, is that the on you're using?

 

Again congrats, and happy listening!


Edited by mab1376 - 1/14/14 at 12:17pm
post #4656 of 10559
Hi!
Where did you get those siemens C3gs from?
They seem to be very rare...
post #4657 of 10559
Quote:
Originally Posted by mab1376 View Post
 

 

I'm a little behind on this thread, whats going on with your headphone jack there?

 

also congrats on getting those tubes working! I'm no too handy, but hopefully I can get a change to try them somehow down the road if i can find a pair and build adapters which I'm hoping is in the thread somewhere. I'm still using 6AV6 tubes a pretty pleased with them overall.

 

Also a quick google on that tube shows an "S" versions with tighter specs, is that the on you're using?

 

Again congrats, and happy listening!

 

Welcome back mab. Boy have you got some catching up to do! And thanks for your encouraging comments...

 

Things have moved on at a frantic pace since 6AV6 land. First we found 6HM5s (TALL bottle type, mine being from Ei Yugoslavia, at 5$ with free shipping) which are simply plug & play on EF95 setting, and which were very good indeed.

Then came double triode land - the 6DJ8 (and variations) land - with a leap in results.

Then came octal land, also with some really good results...you really must burn the midnight oil and go back over the work of such as Audiofanboy and Gibosi et al.

 

As for myself, my foray into 8-pin land has just been with the C3g pentode/come triode - mine being the 'ordinary', but still with the dual getters (1 barium and 1 zirconium). The "S" versions are out of my price range, and to be honest these 'ordinary' ones are so well made and sound so fantastic that I doubt very much whether the (much) greater cost of the Ss is warranted.

 

You will find posts showing different adapters, going back a while, but for the C3g I had to do my own mod from 8 to 7-pin, with different layout .

 

As for the headphone jack...it's gone!! After getting amazing results from wiring my (pure silver) speaker wire direct to the speaker's crossover (I HATE too many connections in the signal/power path), I thought I would do away with the "upgraded" Neutrik jack socket - which I was not at all impressed with - and solder the headphone cable (again pure silver wire) direct to the PCB. And I was VERY pleased with the results. Mind you, it is not so convenient of course for trying different headphones! And I still haven't checked to see whether that prevents the LD from outputting as a preamp...but as neither of these things bothers me (at present) I am enjoying the added sonic benefits.

 

Good luck with your catching up, and hope to see your own findings appearing here very soon. The guys here (as you know) will be only too glad to help you with any queries/problems you may encounter...

 

So, happy rolling mab!

post #4658 of 10559
Quote:
Originally Posted by CollectoR13 View Post

Hi!
Where did you get those siemens C3gs from?
They seem to be very rare...


Hi Collecto.

 

Got them from ebayer emsstrom in Germany - but can't see them listed now (he didn't have very many). Yep, there ain't many about, to be sure! JAC Music has them listed, but they're not cheap (mind you, premier 6DJ8s can be a lot dearer lol!)

post #4659 of 10559

Hi Hypnos 1,

 

Congratulations to your C3g amp mod! If I were to use an adapter, what would I use? I have two setups - one for 12AX7 and one 6DJ8.

 

What are you using for power tubes?

 

 

Hi Collecto13,

 

Could only find one offering on Ebay - bidding is up to $69 for the pair. Selling prices for the past month on Ebay have been between $50 - 70/pair.

 

Here is a link to a source that has a lot of these tubes - prices range from Euro 26 to 175, with over ten varieties (don't know how much shipping is):

 

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC0QFjAA&url=http%3A%2F%2Fjacmusic.com%2Fhtml%2Forder%2Fjacmusic-pricelist.pdf&ei=fafVUueTJpfNsQT-qoKQDg&usg=AFQjCNGj-lDYSfbgmLr6l8a8-rgaK9sCzw&sig2=UYz7_5nSDdipqfHkdlIxCA&bvm=bv.59378465,d.cWc

 

These tubes were used by the German government for long distance intercontinental phone calls and were produced without any compromises; hence the ultra high quality.

post #4660 of 10559
Quote:
Originally Posted by hypnos1 View Post
 

Well folks, I think I may just have found my endgame tube(s) at long last, and I'm afraid it's ciao to the 6DJ8s - never thought that would happen! Even my beloved Tesla E88ccs (gold pins and grids) have been blown out of the water...by the Siemens C3gs I have finally managed to complete the adapters for - they are an 8-pin pentode (can be triode connected) with different pin-out, of course, to the 6AK5.

 

Apparently they were conceived by some VERY demanding engineers, wanting uber low distortion, microphonics, noise etc etc but with high gain, linearity and very long life. All I can say is they worked miracles, because they have not only filled the slight gaps in the otherwise excellent Teslas, but also surpass them in ALL areas - given my equipment and ears, of course.

 

Bass is phenomenal, in detail and extension (slam is too crude a word to apply to these beauties).

Treble ditto, without the occasional sibilance of the Teslas.

Mids have returned nicely, with no loss in the other frequencies - in fact no range dominates to the detriment of others.

Soundstage is truly remarkable - a magic trick that manages to achieve the 3-dimensionality of the Teslas with even more detail...a rare ability I would suspect.

Imaging is precise, along with instrument and voice positioning/separation. Vocals are slightly more forward than the T's, giving a slightly more intimate musical experience while retaining a fine overall balance.

The tonal range is immense, along with dynamic range - from attack thru decay, instruments are taking on a whole new (magical) persona.

 

And the low noise/high linearity pre-requisites are manifested by the dead silence in a 'black' background, and a deliciously 'clean' sound of wonderful clarity.

 

In other words, I am totally blown away, in case you hadn't guessed!

 

Perhaps my (obsessive) desire to keep to a minimum the number of in-line connections and mix of metals may have also helped somewhat...in line with my previous mods, I decided to use pure silver wire for fitting tube to LD socket - in fact I bit the bullet and did away with an adapter as such and connected (scarily!) 1mm wire direct to the tube pins, said wire also acting as the B7 pins, instead of a cut-away tube base. Sealing things in resin to (hopefully) prevent connections becoming DISconnected meant I only really had one chance to get things right...a bit of a nightmare, to say the least!

Anyway, thankfully all was well (so far) and the final result has proved to be worth every ounce of sweat and nervous exhaustion.

This 'pentode' certainly seems like no other, and would explain Yamamoto's choice of the C3 family for some of his lovely amps...

 

The above, of course, is NOT the right photo -  (don't know how to remove it!). Hopefully second time lucky...

 

That's more like it!!

Great stuff man! I knew these C3g were worth trying!

 

As usual, how I would love to be able to directly compare the best 6DJ8 to the best 6SN7 to the best C3g to the best... But, alas, I can't... More like, no one has yet really; except maybe gibosi who's been pretty thorough in comparing the 6DJ8 and 6SN7 types (and other exotic suggestions like the 2C51...).

 

Too many tubes to test, too many adapters to make, so little time and money lol...

 

Anyway, great work! I'm sure you'll be copied and that more people will jump the boat!

post #4661 of 10559

Well now have a totally hum free octal adapter for the 6DJ8 platform.

 

Took an incompatible B9A and cut the bottom off of it with the Dremel and a cutting disc. I wrapped painters tape around the top and bottom, leaving a gap between the two tape pieces as a guide for the disc. If you take your time and go slowly the bottom of the tubes should come off cleanly. Pull the tube innards out and cut off the pin wires long enough to solder to. The pin wires will need to be scrapped and cleaned up a bit so they will take solder. I like to use a just little plumbers flux as it is more corrosive and cleans the pin wires better.

 

Soldered some short pieces of wire to the pins and put heat shrink over the solder joints. Then fill the tube base with hot glue so nothing moves, when that cools enough place the octal socket over top of the assembly pulling the wires out to the side of the pins in the correct spots. Since it would be too hard to tin and strip the wire before hand i just left them all 2" long. The octal sockets I have are machined ceramic and have straight pins for mounting to a PCB. So I pushed the octal pins down into the hot glue and proceeded to cut off strip and solder the wires to the pins. (It's a little tedious but doable.)

 

After all the wires were attached I filled the rest of the space with hot glue and molded it smooth and round with the flat part of the nozzle on the glue gun. Let it cool, plug in an octal and see if the filaments light up. If they do then test with disposable headphones in case you made a mistake in the wiring. ;)

 

I plugged in the 6H9C as they are the only octals I have and proceeded to check out some OM.

 

"Hayya ala salah. From the minaret see.
Toward solidaric ground. Weeps - walk on sadhak."

 

The bass on this song is great and listening with the GMP 8.300's was total enjoyment from the 6H9C.

Enjoy!

:beerchug: 

post #4662 of 10559

Hypnos1,

 

Did you try and other C3g brands with negative results? or did your research just point you to the Siemens?


Edited by mab1376 - 1/15/14 at 12:39pm
post #4663 of 10559
Quote:
Originally Posted by mordy View Post
 

Hi Hypnos 1,

 

Congratulations to your C3g amp mod! If I were to use an adapter, what would I use? I have two setups - one for 12AX7 and one 6DJ8.

 

What are you using for power tubes?

 

 

 

 

 

 

 

Hi mordy.

 

Thanks for your kind words. As for adapter, since the pin layout is different to anything else we have been using, you may as well do what I did and make your own. Unlike me, however, you might prefer to use octal sockets in a way similar to TrollDragon, but direct to a B7 base - either using a cut away base from an old tube, or as I did, using solid core wire through a circle of strong plastic (or similar), letting the wire act as the B7 pins. Of course, the innards need sealing in resin/hot glue/whatever, and GREAT care is needed to ensure correct pin to pin placement - mirror images are a bane, to say the least! (Sorry if I'm "telling Grandma how to suck eggs", but I still get a bit confused sometimes, no matter how careful I am!!..). Because of limited space, I used bare wire for bending hither and thither, and of course had to be EXTREMELY careful to ensure nice gaps between them. So all in all, not too difficult, but it needs careful planning, a fairly steady hand, patience and careful checking and double checking. And as TD mentioned, it's a good idea to test with an old pair of 'phones first, just in case...

Anyway, good luck if you do decide to go ahead...

 

As for power tubes, I have the (extremely) expensive 6N30P-DRs, which do seem to have the edge over others - and Audiofanboy loves 'em, which is good enough for me!

 

Oops, time has slipped away, so I'll post the C3g pin layout tomorrow...

post #4664 of 10559
Quote:
Originally Posted by mab1376 View Post
 

Hypnos1,

 

Did you try and other C3g brands with negative results? or did your research just point you to the Siemens?

 

Hi mab.

 

Actually, the Siemens were the only ones I could find at a reasonable cost - the other brands only seeming to be available from JAC Music at FAR higher prices. And as Yamamoto uses Siemens tubes, I thought they would be more than good enough for me! And they have certainly proved themselves to be so...

 

Ah well, time for supper once more...

 

Cheers!

post #4665 of 10559

i have 2 questions for you "tech" guys:

 

1. what would actually be the worst to happen to my headphones if i did something wrong in using a selfmade adapter?

2. whats a "surge" and how can that affect my amp? Especially concerning a 12AX7 to 6SL7 and an octal tube?

 

thx for replys:)

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