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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 104

post #1546 of 7350
Quote:
Originally Posted by MIKELAP View Post

Thanks gibosi for the great picture dont have those cutters dough . do you think a dremel has to much vibrations while cutting and yes they are japanese tubes . i heard somebody was working on having other sockets made they wouldnt be to go from ef 95 to ef 92 if that possible at all maybe you talked to me about this i dont remember who did. Thanks again .

 

If you have a very steady hand, I am sure a Dremel will work fine. However, I found it difficult to keep the cutting wheel away from neighboring pins, as you can see in this picture. Also, if you try to cut the pins off very close to the glass, and the cutting wheel touches the glass, the tube will likely be destroyed. If you can find a pair of flush cutters, it is much easier (and safer for the tube). :)

 

 

I too remember that someone mentioned working with the Chinese socket converter vendor to obtain a 5 to 7 converter to allow the use of EF92 tubes without having to change jumpers, but I don't know anymore than that.....

post #1547 of 7350
Quote:
Originally Posted by MIKELAP View Post

Got those yesterday not the greatest sounding compared to the 6au6 but  still decent looks like  they are english with  broad arrow ,collecting ww2 stuff thats why i figure they are english could that be 1969 anybody have more infos on these . Thanks

 

 

These appear to be the British military version of the 6AK5W / 5654:

 

http://www.radiomuseum.org/tubes/tube_cv850.html

 

The M8100 / CV4010 is the newer version of this tube.

 

And yes, it appears that they were manufactured in 1969, the 10th week.

post #1548 of 7350

Hi Mikelap,

 

Instead of the Dremel, just use a small cutting pliers - does not have to be the flush cutting kind. If you end up with a little piece sticking out, try to trim it with the cutting pliers. You will be left with a very small piece sticking out. Just take a little electric tape and cover it, or two layers if the piece is still sticking out too much.Works just fine.
 

post #1549 of 7350

my sylvania GB6136 (6AU6) with gold pins arrived today, using the "a" type converted I plugged them into my amp, and they sound fantastic!!!! no noise at all, though they do look a bit wired in the amp

.


Edited by zedmeco - 6/17/13 at 5:13am
post #1550 of 7350

Great news! I was pretty sure your amp could easily handle these new tubes. You just needed to get a good pair.

 

Interestingly, my pair of Sylvania GB6136 with gold pins were pretty noisy when I first plugged them in.  Very disappointing.... But after being burned in, they are now completely quiet.

 

Enjoy! :)

post #1551 of 7350

I am absolutely in love with my Telefunken 6BE6 using with standard EF95 settings.

I emailed NOSTUBESTORE about getting some Siemens 6BE6 to compare... but SOMEONE bought all of them recently according to the owner... confused_face(1).gif

 

I'm sure I could find a pair somewhere else, just haven't looked yet.

 

Eventually I'll try out my EH900S with gold pins.

post #1552 of 7350
Quote:
Originally Posted by mordy View Post

Hi Mikelap,

 

Instead of the Dremel, just use a small cutting pliers - does not have to be the flush cutting kind. If you end up with a little piece sticking out, try to trim it with the cutting pliers. You will be left with a very small piece sticking out. Just take a little electric tape and cover it, or two layers if the piece is still sticking out too much.Works just fine.
 

Thanks mordy thats whats i did finally took the smallest cutters i had and i was left with about 1/16 which i filed off with a small square file i had 

post #1553 of 7350

Sonic bliss?
 

post #1554 of 7350

A couple days ago saw my guy at flea market at guess what i bought some tubes some G.E. 6136  ,C.V. 850, and a pair of Hit Ray clear tops Japanese 6AV6  tubes which i am listening to right now my first impressions are that the soundstage is wide theres a good tight bass i find  the treble to be very present i find to be borderline but still very good younger guys might say a bit hot .sound in general is transparent maybe i would be curious to see what those of you who tried the 6av6 tubes  think . 

 

post #1555 of 7350
Quote:
Originally Posted by MIKELAP View Post

..... a pair of Hit Ray clear tops Japanese 6AV6  tubes which i am listening to right now my first impressions are that the soundstage is wide theres a good tight bass i find  the treble to be very present i find to be borderline but still very good younger guys might say a bit hot .sound in general is transparent maybe i would be curious to see what those of you who tried the 6av6 tubes  think . 

 

 

Welcome to Triode Land! You might be the first to try the Hit Ray 6AV6. I have seen speculation that Hit Ray = Hitachi + Raytheon, but even so, I do not know if anyone here has tried the Raytheon 6AV6 either. It has been my experience that 6AV6 often have a good tight bass and, compared to pentodes, a rather pronounced treble, so I suspect that what you are hearing is pretty typical for this family of tubes. Are you impressed enough to try some more? 

post #1556 of 7350

I've been running 6AV6 tubes for about a month and can vouch for their qualities, especially in the treble department but not only (realism, soundstage, and bass for at least on pair I own). Treble will most likely get "nicer" after 10-20 hours, like on the "hotter" ones I tested though, so I wouldn't worry.

 

OK, it's been bugging me to not know why 6BE6 and 6BY6 heptode -or more precisely pentagrid converters- work better with pin 7 -grid 3- left unplugged or open; not that I've tested it myself yet, but it's the theory behind this that bugs me.

 

Those pentagrid converters have, well, five grids, grid 5 is very simply the same as grid 3 in a pentode, it is just there to catch stray electrons -and send them back to the cathode, to which it is internally connected in this case- so that's easy.

 

Grid 1 is the oscillator grid, and you've all been using it like the typical signal grid in both pentodes (grid 1) and triode (grid.), and it happens to be made to receive one signal anyway, so that makes sense. Grid 3 is the mixer grid and is apparently made to also receive a signal. Grids 2 and 4, internally connected, act both as the screen grid in a pentode (grid 2) and anode for the oscillator grid (grid 1 in a pentagrid converter/heptode).

 

I assume the usual purpose of these tubes is to amplify a signal on grid 1, received and "screened" by grid 2 (and 4), "mixed" to the signal on grid 3, and eventually caught by the anode to be useful to some other electronic section. Not that any of this matters for our purposes.

 

Now, it appears that these tubes don't give their best when you tie grids 2+3+4 to the anode, and yet they seem to work the same way as triode-strapped pentodes when you just ignore grid 3 and strap grid 2+4 to the anode -grid 5 being hardwired to the cathode regardless- an use grid 1 to send the audio signal.

 

Thinking from different sources I've just read, things I'd read about the use of 6AU6 pentodes in microphones -more on that below- and the using the coincidencial discovery above, I'm pretty sure there are alternative ways to plug these tubes, that could work just as well and perhaps better -which would be the obvious goal here.

 

Apparently, people have been using 6AU6 tubes triode-strapped in funny ways in for microphone buffer/amplification purposes for years. In order to get the lowest noise possible -pretty important when you're recording, say, a voice- they often grounded the anode, and used the grid 2 as the de facto anode; I assume grid 3 was still strapped to the cathode.

 

On these pentagrid converters, we have a total of five grids -but only three pins- and one anode to play with. So, here are a few ideas that I'd like to test or at least brainstorm, most of which have little reason to explode lol:

 

- Using grid 2 and 4 as the anode, with both grid 3 and anode left "open" (in theory they should be grounded in this case scenario). So, chopping pin 5 (anode) and running the tube in the EF95 setting basically. Should produce sound, may be good or bad, should not explode.

 

- Using both grid 1 and grid 3 as for the audio signal. I have no idea is this can work properly since you have grid 2 sandwhiched between them. Basically, it would imply wire-modding pins 1 and 7 together and running the tube on the EF95 setting.

 

- Using grid 3 instead of grid 1 for the audio signal. Again, may be difficult since grid 2 would be in the way between the cathode and the audio signal. Would mean chopping pin 1 and wire-modding pin 7 to socket hole 1, which in and of itself is complicated. EF95 setting.

 

- Using grids 2+3+4 as the audio signal grid and leaving grid 1 disconnected. Same issue as above, no idea if it would work well, and same pin mod but EF92 setting.

 

- Using grids 1 and 3 as the audio signal grid and using grids 2 and 4 as the de facto anode, with official anode disconnected. Again, maybe it would work, maybe not, hard to say. Would mean chopping pin 5 off, and wire-modding pins 1 and 7 together.

 

Anyway, I need to investigate this some more, but you get the idea, there may be more possibilities to plug heptodes -and I'm starting to understand why they're not meant to have grid 3 connected to grids 2 and 4 and not running a signal (the tube is meant to run two signals).

 

Some resources, half of which is beyond me:

https://en.wikipedia.org/wiki/Pentagrid_converter

http://www.diyaudio.com/forums/tubes-valves/163842-possible-use-pentagrid-tubes.html

post #1557 of 7350
Quote:
Originally Posted by gibosi View Post

 

Welcome to Triode Land! You might be the first to try the Hit Ray 6AV6. I have seen speculation that Hit Ray = Hitachi + Raytheon, but even so, I do not know if anyone here has tried the Raytheon 6AV6 either. It has been my experience that 6AV6 often have a good tight bass and, compared to pentodes, a rather pronounced treble, so I suspect that what you are hearing is pretty typical for this family of tubes. Are you impressed enough to try some more? 

The impressions i gave you before with regards to the Hit Ray 6AV6,  i was using my Denons d-5000 with my go to track which is Duke Robillard Albie Aint Here now i went with the senns hd800's and man detail i definetily like those tube clean sounding bass very good dont know how they will sound in 20 hours but i like em after 4 or 5 hours i would try other tubes why not

post #1558 of 7350
Quote:
Originally Posted by hypnos1 View Post

 

Hi mab.

 

My Siemens EK90s just keep getting better - I'm sure your Telefunkens will blow you away!..Hope so...

Will have to give them a try and see how they compare Can't see how anything can better these EK90s - certainly on a simple ef 95 setting. But I'm forgetting the amazing Audiofanboy!!...

I fear you will now be disappointed with the EH900Ss, though...

Happy listening!

 

These Telefunkens are absolutely amazing! Using them with my MK IV SE, PS Audio Digital Link III with some upgraded parts, 6N6P-IR power tubes, and of course my beloved HD650's.

 

 

 

Someone would have to make a really convincing argument to make me want to try anything else... can this get better?

 

...anyway I'm using with a standard EF95 settings, are there any better recommended settings? I see some people recommend snipping some pins? Or is that only for the 6AV6?

 

Has anyone directly compared them to the EK90/6BE6?

post #1559 of 7350

Gave a listen to the Tung-Sol 6BE6 on EF92 setting and the Hit Ray 6AV6 and to me the 6AV6 are the clear winner  very wide soundstage with the hd800 starting to like these very much tomorrow might try to compare  them to the 6136 or 6AH6 anybody try this combo yet youll save me a  jumper change for a while. My lack of patience thanks you. 

post #1560 of 7350
Quote:
Originally Posted by MIKELAP View Post

Gave a listen to the Tung-Sol 6BE6 on EF92 setting and the Hit Ray 6AV6 and to me the 6AV6 are the clear winner  very wide soundstage with the hd800 starting to like these very much tomorrow might try to compare  them to the 6136 or 6AH6 anybody try this combo yet youll save me a  jumper change for a while. My lack of patience thanks you. 

 

Do you prefer the 6BE6 on the EF92 setting as opposed to the EF95 setting?

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