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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 111

post #1651 of 8466
Quote:
Originally Posted by siles1991 View Post

alright thanks does it mean I can run it with ef95 settings and just stick it in?

 

The immediate change I notice with the Amperex on 2-7 strap is a much brighter and forward presentation compared to on standard EF95 with a sweet relaxed sound.

post #1652 of 8466
Quote:
Originally Posted by mab1376 View Post

 

The immediate change I notice with the Amperex on 2-7 strap is a much brighter and forward presentation. listening to some Rodrigo y Gabriela it has a very wide soundstage. Compared to it on the standard EF95 settings with a sweet relaxed sound.

 

My Raytheon 6GX6 sound also very nice with the 2-7 strap, much like the EH900S. Previously I was only using them with EF92 settings. Very transparent, like there's nothing between me and the music. Amazing for Jazz.


Edited by mab1376 - 6/25/13 at 6:14am
post #1653 of 8466

Was reading page 77 .DId i understand this correctly . when my jumpers are  in EF95 mode if i strap PIN 6 AND 7  i will be in EF 91/92 mode is that correct if it is im gonna kick myself in the b.... and probably more than once ! 

post #1654 of 8466
Quote:
Originally Posted by MIKELAP View Post

Was reading page 77 .DId i understand this correctly . when my jumpers are  in EF95 mode if i strap PIN 6 AND 7  i will be in EF 91/92 mode is that correct if it is im gonna kick myself in the b.... and probably more than once ! 

 

If that's the case I'm never changing jumpers again!

post #1655 of 8466
Quote:
Originally Posted by MIKELAP View Post

Was reading page 77 .DId i understand this correctly . when my jumpers are  in EF95 mode if i strap PIN 6 AND 7  i will be in EF 91/92 mode is that correct if it is im gonna kick myself in the b.... and probably more than once ! 

The Little Dot straps pins 5 and 6 together on the circuit board regardless of what setting you use. So if you strap 5 and 7, as we have been doing for triodes, this is actually the same as strapping 6 and 7. So, yes if you strap either 5 and 7, or 6 and 7, you can run EF 91/92 tubes in the EF 95 setting.


Edited by gibosi - 6/25/13 at 7:29am
post #1656 of 8466
Quote:
Originally Posted by gibosi View Post

The Little Dot straps pins 5 and 6 together on the circuit board regardless of what setting you use. So if you strap 5 and 7, as we have been doing for triodes, this is actually the same as strapping 6 and 7. So, yes if you strap either 5 and 7, or 6 and 7, you can run EF 91/92 tubes in the EF 95 setting.

OUCH! OUCH!

post #1657 of 8466

 

Quote:

Originally Posted by mab1376 View Post

 

My Raytheon 6GX6 sound also very nice with the 2-7 strap, much like the EH900S. Previously I was only using them with EF92 settings. Very transparent, like there's nothing between me and the music. Amazing for Jazz.

 

Try the 6EW6 with 2/7 strap, I found it cleaner than the 6GX6. Sounds a bit bass weaker but opener and quite nice really. The nice heptodes are still a class up though IMO. Amperex E91H 2/7-strap sounds very nice, yes brighter and not too much ambience but more neutral with better definiton. It feels a bit like in tube wonderland. :)

 

 

     Quote:

Originally Posted by siles1991 View Post

alright thanks does it mean I can run it with ef95 settings and just stick it in?

 

Yes.


Edited by Acapella11 - 6/25/13 at 11:28am
post #1658 of 8466
Quote:
Originally Posted by Acapella11 View Post

 

Try the 6EW6 with 2/7 strap, I found it cleaner than the 6GX6. Sounds a bit bass weaker but opener and quite nice really. The nice heptodes are still a class up though IMO. But it feels a bit like in tube wonderland. :)

I have so many on my desk i've been cycling through, I do very much like the TFK EK90 but i haven't even tried it with the optimal 7-1 strap yet.

 

TS 6BE6

TFK EK90

Lorenz EK90 (on the way)

Amperex E91H

Raytheon 6GX6

TFK EH900S

 

 

I found a pair of Raytheon 6EW6 to compare. I'll see how i like it in comparison once I get them.

post #1659 of 8466

And here comes the next one:

 

1/7-grid strap for 6CB6, 6CJ6, 6DK6, 6EW6, 6GM6, 6AM6, 6GY6/6GX6, lol

 

Tested for 6EW6 and 6GY6/6GX6. Sounds a bit slower and with very round treble. Probably not the optimal setting but works fine and sounds OK.

Could somebody confirm this for the other families, just to be sure?

 

Who said can of worms...? haha


Edited by Acapella11 - 6/25/13 at 11:45am
post #1660 of 8466

Tested Hit Ray 6cb6a with 2-7 strapped pretty good bass with the closed Denons how sweet it his nice and clean right after cant believe i missed this i mean right after with 5-7 wire mod to EF91-92setting with Hit Ray 6av6 5-6 pin cutoff tighter bass wider soundstage cleaner sounding a bit . what nice tubes we are sampling these days .

post #1661 of 8466

Hi A11,

 

Tried my Tung Sol 6CB6 with the E95 1-7 strap. Yep it works, but no, does not sound right. What comes to mind is a transistor radio that is not tuned on the spot. You can hear clearly but the sound is off - sounds sibilant and compressed with details and dynamics missing.

 

Switched back to my RCA 6BY6 tubes with the 1-7 strap. Delicious, everything is there with a glorious super detailed shimmering

high end. However, I am missing the punchy bottom end, sound stage and instrument separation of my Tung Sol 6AH6WA tubes.

 

Which heptode would combine both virtues? The Siemens EH90?

 

Truth is, I ordered a pair of the Siemens EH90 based on Gibosi's recommendation - thanks. Because of my self imposed limit of $8/tube including shipping, I took a chance on the best offer feature and offered 4 instead of 5 euros/tube, which, with shipping, brought it down to under $8/tube. The offer was accepted - will report when the tubes arrive.

 

OK - a confession, since everybody on this blog is self effacing and don't mind admitting mistakes and blunders. Some time back I reported that the RCA heptodes I tried on the EF95 1-7 strap had a very low volume and did not sound right. I finally found out what the problem was: I tried to be too organized! I actually opened the RCA 6BY6 boxes and took out the two tubes and tried them - sounded awful! Why? I had put two unknown 6AU6 tubes in there with the markings worn off - wrong tubes! Please strike my previous post #1671 from record.

 

I have to go back to my shoe box storage with pairs of tubes joined together with rubber bands. That way I have to look at the tubes before I put them in and don't have to rely on the box markings.....

 

Right now I am listening the these wonderful heptodes - all what they are hepped up to be!

post #1662 of 8466

I got a pair of Telefunken EH900S tubes in the mail today. Genuine Ulm factory Tele tubes with golden pins -and "Made in Germany" actually written on the glass- they look like the ones here:

 

http://www.radiomuseum.org/tubes/tube_eh900s.html

 

These are heavy. Like, Russian -DR standard heavy. Thick glass, thick metal poles holding the grids inside the tube, and clean solder points to -did I mention thick?- wires at the tube base. These look great and without any doubt some of most solidly built tubes I've bought -especially for driver tubes! These are supposed to be 10000 hours low-noise tubes, so pretty high spec.

 

They're burning in, haven't listened to them except to confirm sound flows in both channels. Directly 7-1 strapped, as I'm pretty sure that will yield the best results. Impressions later today.

 

Speaking of grids, while on a heptode, considering there are two control grids and different applications, we can consider that a variety of strapping methods make sense, such as the 7-1 strap. On a pentode, strapping grid 3 -not a control grid- to grid 1, with grid 2 -strapped to anode- makes little sense and bound to sound bad... Anyway, I personally would not bother testing all my pentodes in with pins 1 and 7 strapped, as I see no point in doing that.

 

If you really want to try an interesting experiment -one that should sound good- try strapping grid 1 to the cathode on a heptode, and strapping grid 3 to socket hole 1. That way, you neutralize grid 1, and only get one control grid like in a triode. That, I'd want to see someone test, if only to see how to tie a pin to an empty socket hole -of course an adapter would be way easier.

 

Speaking of testing, I found and bought some IBM 1680 tubes today for a petty sum of money in the US. These are basically RCA 6BE6 from 1950 sold to IBM for IBM "computers" as switching tubes, but they are in effect closer to 6BY6 tubes, as they were made so that grid 3 would have a uniform pitch and therefore sharp cutoff. So, I guess, industrial-grade RCA 6BY6 prototypes...? At least that's what I'm hoping for lol!

post #1663 of 8466

Would material used be important for the strapping i guess copper is better than steel right .Update found some copper wire made a few straps seems to help the bass department and everything else  hmm !


Edited by MIKELAP - 6/26/13 at 7:18am
post #1664 of 8466
Quote:
Originally Posted by MIKELAP View Post

Would material used be important for the strapping i guess copper is better than steel right 

 

I would assume so. I personally use some high quality silver stuff that I found scraps of at the electronics factory I work at. Only needed about 2 inches.

post #1665 of 8466
Quote:
Originally Posted by Audiofanboy View Post

- 6BE6: grid 1 = sharp cutoff, grid 3 = remote cutoff (cutoff in triode mode when tied together ? )

- 6BY6: grid 1 = sharp cutoff, grid 3 = sharp cutoff (so we'd expect a sharp cutoff trait when triode strapped, probably...)

- 6CS6: grid 1 = sharp cutoff, grid 3 = sharp cutoff (so same as above...?)

 

 

Quote:
Originally Posted by Audiofanboy View Post

If you really want to try an interesting experiment -one that should sound good- try strapping grid 1 to the cathode on a heptode, and strapping grid 3 to socket hole 1. That way, you neutralize grid 1, and only get one control grid like in a triode. That, I'd want to see someone test, if only to see how to tie a pin to an empty socket hole -of course an adapter would be way easier.

 

 

Given that the 6BE6 grid 3 is remote cutoff, do you see a problem in using it as the control grid?  Maybe it would be better to tie grid 3 to the cathode? But of course, this is what strapping 2-7 accomplishes...

 

Well, the only way to know for sure is to try. :)

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