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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 257

post #3841 of 5890

Hi all,

 

Finally caught up slightly  and built two separate spider web style adapters for 12AX7 and 6DJ8. These tubes really are MUCH better than anything we tried before.

 

One adapter was soldered by a friend, and the second I screwed together using the Vectors and a breadboard which turns out to be much easier.

 

The 6AV6 tubes are supposed to be 1/2 of the 12AX7. I noticed that the 6AV6 tubes changed very much in character during burn-in (for the better) and took around 40-50 hours to reach full potential.

 

As regards the 12A7 and 6DJ8 families, does anybody know how the long the burn in period is, and if they change a lot in sound during and after burn in? 

 

Right now I am listening to a Dutch Amperex Tektronix 6DJ8 from 1975 with the A frame getter. Funny, in my 6AK5 odyssey I found the Amperex tubes to have the strongest bass. With the Amperex 6DJ8 the bass is striking and goes lower (sub woofer territory) than any tube I tried. Overall, an excellent tube with nothing to criticize and only to enjoy listening to.

 

Artsi, I am just shaking my head in disbelief over what you accomplished with the octal tubes. To do what you are capable of is way beyond anything I can aspire to. I assume that bigger is better (heat dissipation?), but really, how does the sound of the octals compare to say the 6DJ8?

 

Trolldragon, when you have perfected the flying tube adapter, please let me know so that I can order one. My own adapters are very fragile, and I am afraid to as much as breathe on them lest some little wire will get lose or break....

 

Is less better? On a personal note, my receiver blew up, and I had it repaired for around $200. First I thought that I had crossed two speaker wires by accident when I moved a speaker. After carefully rewiring and going over all connections, I plugged in the receiver. Within a few minutes, poof, poof, and that sickening white acrid smoke again. Turns out that one speaker had shorted out internally and blew, and that is what caused the receiver to short out. Again.

 

So I am stuck with my 1980's Sony receiver and two speakers instead of four. Meanwhile my two subwoofers are disconnected. Still, with the Amperex 6DJ8 the sound is quite nice.

 

Oh well, less is at least livable....

post #3842 of 5890
Hi mordy will do, I'll probably not play in the 6DJ8 game so I'll PM you about sending mine your way when I have it assembled and solid.
post #3843 of 5890
Quote:
Originally Posted by mordy View Post
 

Hi all,

 

Finally caught up slightly  and built two separate spider web style adapters for 12AX7 and 6DJ8. These tubes really are MUCH better than anything we tried before.

 

One adapter was soldered by a friend, and the second I screwed together using the Vectors and a breadboard which turns out to be much easier.

 

The 6AV6 tubes are supposed to be 1/2 of the 12AX7. I noticed that the 6AV6 tubes changed very much in character during burn-in (for the better) and took around 40-50 hours to reach full potential.

 

As regards the 12A7 and 6DJ8 families, does anybody know how the long the burn in period is, and if they change a lot in sound during and after burn in? 

 

Shocking, right? Yeah, I'm definitely not going back to pentodes/heptodes; it would feel like a punishment to do so lol...

 

The 6DJ8 in particular are very very nice on headphones, but the 12AX7 (the Tele ones I have at least) seem to work very well for broader applications too, like through speakers. On headphones though, the OG are just miraculous! I just found two more early 60's USN-CEP Amperex 6922, so I'll have three different tubes to play with and compare to the OG soon.

 

As far as burn-in goes, I wouldn't expect any dramatic change like some extreme tube types we've tried, just some basic bass tightening and de-muddiness by 10-12 hours, and a slightly more mature and focused sound by 20-50 hours. Those tubes are so good out of the box, you don't even think of doing a formal burn-in with them, you just listen to music!

post #3844 of 5890
Quote:
Originally Posted by hypnos1 View Post
 

 

You gonna make 'em even SMALLER? Ye Gods, AFB, you've got much nimbler fingers and better eyes than mine then... GOOD LUCK! Mind you, I was using B9As with gold  'pins' inside rather than terminals on the outer edge - I DEFY you to make a 1/2" one with the latter babies!! Look forward to seeing your final result...

 

Would have loved to test the contraption before gluing, but was afraid of possible wire connection damage when trying to extricate the tiny tube/socket base from the LD before really securely attached to the body...catch 22?

 

OK, lol, I lied... Let's just say my goal is to remain below the inch limit in height, basically. 2.5cm or so should be achievable. Maybe?

post #3845 of 5890

HI AFB,

 

Agree with everything you say. I have a Sylvania 12AX7 that sound wonderful through what is left of my speakers.

 

I did notice a bass tightening as well, but as you say, these tubes sound great just out of the box, and I do not feel the need to wait for the grueling burn in period to finish to enjoy the tubes.

 

TrollDragon: IMHO you should try the 6DJ8 tube - with a little patience you can buy an Amperex for less than $10. The wiring entails only a few changes.

post #3846 of 5890
Quote:
Originally Posted by TrollDragon View Post

Hi mordy will do, I'll probably not play in the 6DJ8 game ......

 

I hope you will give these tubes a chance. Otherwise, you will be missing out on the best tubes I have ever rolled in my LD!

 

Yes, they can be expensive, but if you are patient, you can find some good deals. As Mordy notes, Amperex are plentiful and can often be found for as little as $10/each. The Teslas are also excellent and also can be found for as little as $10/each. And every so often, a great deal pops up. In today's mail I received a Valvo E88CC, with gold pins, manufactured in the Hamburg factory, which cost me only $18. And it sounds great!:)

 

post #3847 of 5890
Quote:
Originally Posted by mordy View Post
 

Is less better? On a personal note, my receiver blew up, and I had it repaired for around $200. First I thought that I had crossed two speaker wires by accident when I moved a speaker. After carefully rewiring and going over all connections, I plugged in the receiver. Within a few minutes, poof, poof, and that sickening white acrid smoke again. Turns out that one speaker had shorted out internally and blew, and that is what caused the receiver to short out. Again.

 

So I am stuck with my 1980's Sony receiver and two speakers instead of four. Meanwhile my two subwoofers are disconnected. Still, with the Amperex 6DJ8 the sound is quite nice.

 

 

Bummer! :(

 

But you might try connecting your one good subwoofer. There is virtually no "stereo" at these very low frequencies, so you won't really be missing anything by having only one subwoofer.

post #3848 of 5890
Quote:
Originally Posted by mordy View Post
 

 

Artsi, I am just shaking my head in disbelief over what you accomplished with the octal tubes. To do what you are capable of is way beyond anything I can aspire to. I assume that bigger is better (heat dissipation?), but really, how does the sound of the octals compare to say the 6DJ8?

Oh well, less is at least livable....

I think that this octals-adapter is so lovely, that i'm not going back to any miniatyre tubes. These tubes do not get very hot and amplifier does not get warm at all. Powertubes have only 0.6A heaters and driver 0.3A. 

 

I have been studying hard about how people have reviewed different octal tubes and how they compare each other. Most say that these cheap russian 6N9S and 6N8S sound crappy. Mine are not even vintage, driver 6N9S is from -88 and from powertubes other 6N8S is Sovtek -80 and the other is normal russian 6N8S -82. I have Sovtek 6SL7GT (same 6N9S still), but it is defective. It starts to keep little weird changing hum in left channel after about 5minutes of use. I have been thinking that if these sound crappy, then how insanely good could better tubes sound. :basshead:

 

So i ordered 2 different 6SU7GTY (premium 6SL7GT with matched triodes and 10000h life), 4 different 6SL7GT, one 5691 (premium 6SL7GT with 0.6A heater), 2 5692 (premium powertube 6SN7GT) and 2 6SN7GT as power. Hope i get these next week and in one piece.

post #3849 of 5890

Eureka! B9 to B7 adapter number 2 is finished...and actually WORKS - phew! The LD doesn't look too bad for it, either, thank goodness.

 

With the second Voskhod 6N2P-ER in place, I have to say I am VERY impressed - my system, at least, is falling in love with them already. Soundstage? - there's just one word sums it up : 5.1 surround! OK, more than one...Another would be EXCITING. Although new-in impressions are not to be trusted (notwithstanding previous posts re less need for burn-in), I decided to pop in the Japanese (Amperex) 6DJ8s - one with 'Holland' on it - and what a difference : laid-back as opposed to WOW-exciting. Nowhere near the same soundstage and 'airiness', nor 'sparkly' treble as the Voskhods. Even if one or both of the RCAs were made by Matsu****a, they are definitely from Amperex machinery and one would assume that they would perform fairly closely to the Holland ones...perhaps I am assuming too much? If they ARE a close second, all I can say is they have a long way to go to outperform the V/hods - I suspect there is more chance of the (at present) weaker mids of the latter developing as the treble tones down, than the RCAs livening up to any great degree...ie somewhat disappointed in this regard. Still, it's early days yet, so I must be patient and see what the other 6DJ8s and 6922s deliver...not to mention the Tesla PCC88s yet to arrive...

 

But back to the Voskhods, perhaps one shouldn't be TOO surprised as JAC Music rank the 6N2P as one of the top 10 'ECC83s' you can get, and as I have been lucky enough to get the special ER version this could well explain the current situation. I do believe Audiofanboy mentioned something about the 12AX7 specs matching our LDs better than the ECC88s, so perhaps this is also helping...I do also like the much higher gain from these babies. Ah well, time will tell. Whatever, these double triodes certainly are the business. And well worth the effort in making those adapters...viz : the finished result...

 

post #3850 of 5890
Quote:
Originally Posted by hypnos1 View Post
 

With the second Voskhod 6N2P-ER in place, I have to say I am VERY impressed - my system, at least, is falling in love with them already. Soundstage? - there's just one word sums it up : 5.1 surround! OK, more than one...Another would be EXCITING. Although new-in impressions are not to be trusted (notwithstanding previous posts re less need for burn-in), I decided to pop in the Japanese (Amperex) 6DJ8s - one with 'Holland' on it - and what a difference : laid-back as opposed to WOW-exciting. Nowhere near the same soundstage and 'airiness', nor 'sparkly' treble as the Voskhods. Even if one or both of the RCAs were made by Matsu****a, they are definitely from Amperex machinery and one would assume that they would perform fairly closely to the Holland ones...perhaps I am assuming too much? If they ARE a close second, all I can say is they have a long way to go to outperform the V/hods - I suspect there is more chance of the (at present) weaker mids of the latter developing as the treble tones down, than the RCAs livening up to any great degree...ie somewhat disappointed in this regard. Still, it's early days yet, so I must be patient and see what the other 6DJ8s and 6922s deliver...not to mention the Tesla PCC88s yet to arrive...

 

Welcome to double triode land! :)

 

I found the Voskhod 6N2P-EV to be less bright than Holland-made Amperex 6DJ8, with a strong, but somewhat loose bass. And this was after 20 hours of use. But you have a pair of -ERs, not -EVs, so yours may well sound different. Further, I haven't heard any of the Japanese-manufactured 6DJ8s, so I have no idea how they might compare to Holland-made Amperex. Looking forward to learning how your Voskhods compare to your future acquisitions. Currently, my favorite Soviet tube is a 1979 Voskhod 6N23P.

 

I had a nice pair of Tesla PCC88 and thought that they were very good sounding tubes. However, their build-quality was lacking. Both of the Teslas broke as a result of bending and then re-straightening the pins. But since you won't be mangling your tubes, you should be good. lol :)

post #3851 of 5890
Quote:
Originally Posted by hypnos1 View Post
 

... I decided to pop in the Japanese (Amperex) 6DJ8s - one with 'Holland' on it ... Even if one or both of the RCAs were made by Matsu****a, they are definitely from Amperex machinery ...

 

Please, let's try to call things by their proper names. It was not Amperex machinery. Even the machinery of the Amperex tube plant in Hicksville, New York was supplied by Philips, of which Amperex was a US subsidiary.

post #3852 of 5890

Hey mordy!
 

You have a MK III Yes?

So I am sure that the pipe adapter will fit can I get you to measure the distance between the two red lines.

Basically it is from the left edge of the case hole to the left edge of the next case hole, not the gold rings.

Or you can measure between the exact center of one tube socket to the center of the other. I am not sure if the MK III is the same width as the MK IV.

----

This will be a one-off "Polished Copper Tube Adapter", there is just way too much labor involved with only a Dremel and no other shop tools.

Also do you want it wired for 12AX7 or 6DJ8? Once finished it cannot be changed.

 

Thanks for all the recommends guys but I am not going to play, I have a difficult time chasing $5 tubes let alone $10-$20 ones, it's just not in the cards right now, possibly down the road I'll get involved with some. ;)

:beerchug:

post #3853 of 5890
Quote:
Originally Posted by TrollDragon View Post
 

Hey mordy!
 

You have a MK III Yes?

So I am sure that the pipe adapter will fit can I get you to measure the distance between the two red lines.

 

Basically it is from the left edge of the case hole to the left edge of the next case hole, not the gold rings.

Or you can measure between the exact center of one tube socket to the center of the other. I am not sure if the MK III is the same width as the MK IV.

 

Also, you will want to make sure the driver tubes are oriented the same way. My assumption is that the orientation on the III and IV is the same, that is both driver tubes "face" the same direction. However, on my 1+, one driver tube "faces" left and the other "faces" right.

post #3854 of 5890
Quote:
Originally Posted by gibosi View Post
 

 

Also, you will want to make sure the driver tubes are oriented the same way. My assumption is that the orientation on the III and IV is the same, that is both driver tubes "face" the same direction. However, on my 1+, one driver tube "faces" left and the other "faces" right.


Great point!

So a top down picture of the sockets without tubes would be good as well.

Both of the adapter bottoms can turn a little in each direction to allow for easy alignment.

:beerchug:

post #3855 of 5890
Quote:
Originally Posted by TrollDragon View Post
 

Hey mordy!
 

You have a MK III Yes?

So I am sure that the pipe adapter will fit can I get you to measure the distance between the two red lines.

Basically it is from the left edge of the case hole to the left edge of the next case hole, not the gold rings.

Or you can measure between the exact center of one tube socket to the center of the other. I am not sure if the MK III is the same width as the MK IV.

----

This will be a one-off "Polished Copper Tube Adapter", there is just way too much labor involved with only a Dremel and no other shop tools.

Also do you want it wired for 12AX7 or 6DJ8? Once finished it cannot be changed.

 

Thanks for all the recommends guys but I am not going to play, I have a difficult time chasing $5 tubes let alone $10-$20 ones, it's just not in the cards right now, possibly down the road I'll get involved with some. ;)

:beerchug:

 

I measured with a vernier and from  center to center it measures 1.570 or 40 m.m.(1.575) i measured this from holes in chassis not the rings so it should be the same as littledot 4 but sockets arent exactly in middle read next post


Edited by MIKELAP - 11/8/13 at 4:56am
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