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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 376

post #5626 of 8778
Quote:
Originally Posted by henree View Post
 

This is my first pair of these types of tubes. I would not have the d7000 if they always sounded this crisp. There was no info on ebay about these tubes. It could be NOS. Is it normal for certain tubes to be harsh when 1st listenig to them? Hopefully the 6hm5 smooth out over time.

Let them simmer for a while . For my part it depends on the track they are not sibilant usually.  Some tubes like the Voskhod 6ZHIP-EV its been reported that they need up to 100hours to simmer down .so i would say yes 

post #5627 of 8778
Quote:
Originally Posted by henree View Post
 

This is my first pair of these types of tubes. I would not have the d7000 if they always sounded this crisp. There was no info on ebay about these tubes. It could be NOS. Is it normal for certain tubes to be harsh when 1st listenig to them? Hopefully the 6hm5 smooth out over time.

 

It is likely that your tubes are NOS, and therefore, it is likely that they will change for the better after 20 hours, or more. Typically, after burning in, bass tightens up and highs smooth out. My experience was with the GE 6HM5, but other posters always spoke very highly of the Sylvania. 

post #5628 of 8778
Quote:
Originally Posted by mordy View Post

 

Continuing my exploit of possible octal driver tubes for the the LD MKIII. Found a 12SN7GT Westinghouse tube and bought it mainly because it was inexpensive - less than $4 shipped. This tube has a side getter and the code 5R13, (maybe April 1955?).

 

Was just going to see if it lights up and makes sound and check out other tubes in this lot, but I can't get myself to pull it out of the socket; it is that good

 

I have yet to purchase a Westinghouse 6SN7. My thinking is that Westinghouse never manufactured this tube, but simply sourced from others and relabeled. But I am not sure.....

 

But of course, a good tube is a good tube, regardless of label. :)

post #5629 of 8778

Found this great case very good condition on Ebay                                                                                                                                                                                                                                                             

                                                                                  

                                                                                    

post #5630 of 8778

Nice Case!

post #5631 of 8778

Thanks ,had the tubes out of the boxes took a while to put them back in but now there in one place .

post #5632 of 8778
Quote:
Originally Posted by gibosi View Post
 

 

Yes, the pin-out of 6SN7-type Octal tubes is completely different than the 9-pin 6DJ8s and 12AU7-type tubes. And it gets more complicated. The 7N7, the 8-pin Loctal version of the 6SN7GT, has a pin-out completely different from the Octal form. And the ECC40, the European 8-pin Rimlock version of the 6SN7GT, has a pin-out completely different from both the Octal and the Loctal forms.

 

In the 9 pin socket, if you are running 6DJ8-type tubes, pin 9 is the electrostatic shield and should be tied to pin 8. If you are running 12AU7-type tubes, pin 9 is part of the heater circuit when running these tubes in the 6 volt mode.

 

Yes indeed gibosi, all these different pin-outs make for very fiddly adapter-construction!

Actually - as perhaps I didn't word it properly - I was wondering if, due to the different triode# attribution (as always shown by a 'from below' view of tube base), it is OK to basically link the 6SN7's a1, g1, k1, h1 to LD's a2, g2,k2,h2, and vice-versa....the pin routing being much easier this way?...

 

Cheers!


Edited by hypnos1 - 3/27/14 at 1:46pm
post #5633 of 8778
Quote:
Originally Posted by hypnos1 View Post
 

 

Yes indeed gibosi, all these different pin-outs make for very fiddly adapter-construction!

Actually - as perhaps I didn't word it properly - I was wondering if, due to the different triode# attribution (as always shown by a 'from below' view of tube base), it is OK to basically link the 6SN7's a1, g1, k1, h1 to LD's a2, g2,k2,h2, and vice-versa....the pin routing being much easier this way?...

 

In the special case of power tubes, I suspect this would be OK. It is my understanding that the LD parallels the 6H30's two triodes, essentially transforming the 6H30 from a double triode to a single triode, so maintaining the correct internal left and right orientation would no longer matter. And therefore, it would be the same when you plug a 6SN7 into the LD. The two triodes are paralleled into one and the internal orientation no longer matters. So it should be fine... :)

post #5634 of 8778
Quote:
Originally Posted by mordy View Post
 

Hi I luvmusic 2,

 

Wishing you good luck in making the adapters. If possible, could you please take some pictures when you make them so that I can better understand how to wire in the power supply?

 

I wonder if I could run the the LD MKIII with 6080 tubes as power tubes if I wired in an external power supply to supply each tube with 2.5A.

 

Don't know what the amplification factor of 2 means in regard to using these tubes as power tubes.

Sure i will post a picture as soon as it's done.For 6AS7 i should asked before i bought them will it's too late now it's been shipped and i'am willing to try it as a Power tube and driver tube as will.Someone has to try it and that would be me.

post #5635 of 8778
Quote:
Originally Posted by gibosi View Post
 

 

In the special case of power tubes, I suspect this would be OK. It is my understanding that the LD parallels the 6H30's two triodes, essentially transforming the 6H30 from a double triode to a single triode, so maintaining the correct internal left and right orientation would no longer matter. And therefore, it would be the same when you plug a 6SN7 into the LD. The two triodes are paralleled into one and the internal orientation no longer matters. So it should be fine... :)

 

Thanks gibosi...suspected as much. Just have to get ordering my silver wire now, and can proceed with more confidence! Will be interesting to see how my adapters compare to the bought ones (will be rather miffed if there is no difference after all!!).

 

Cheers once more.

post #5636 of 8778

Hi G,

 

Seems to me that Westinghouse did manufacture their own vacuum tubes. Here is a snippet from an interview:

 

"The war ended and then came a time when things were going very slowly and progress was not to my liking. I got an invitation then from Westinghouse. Westinghouse by the consent decree after at about 1930 had to stay out of the receiving tube business. But by 1950, they could make receiving tubes again. Westinghouse wanted to make not only receiving tubes but more power tubes, cathode tubes, pick-up tubes and what have you — the whole shebang! So I accepted the job and became chief engineer of the newly created Westinghouse tube division. I had a marvelous time because I always wanted to build something from scratch. I hand-picked the engineers, I built up a patent department for the tube division and so forth. It was wonderful. We started to work first in Bloomfield and then the location was changed in 1952 to Elmira in New York State, where they built a new factory. After several years the aims of the company changed. The management in East Pittsburgh had different ideas. There was a slump of business, and I thought of leaving the company. I got an early retirement that was accepted, and I was free. Then I looked around. I had a few offers, but RCA invited me and discussed things with me and I felt inasmuch as I knew RCA and most of the personnel very well I would be more effective there than if I would go somewhere else and start from scratch. So I became a consultant for RCA, worked on semiconductors on germanium, silicon, on methods of making transistors. I had a grand glorious time."

 

Here is the link to a lengthy interview with a tube pioneer:

 

http://www.ieeeghn.org/wiki/index.php/Oral-History:Ernst_Lederer

post #5637 of 8778
Quote:
Originally Posted by mordy View Post

 

Seems to me that Westinghouse did manufacture their own vacuum tubes. 

 

Yes, this strongly suggests that Westinghouse made tubes in the 1950s. And this also explains why we don't see any Westinghouse tubes in the 1940's, during the war.  So I guess I will have to get myself a nice Westinghouse tube. :)

post #5638 of 8778

Mordy,

 

As you search for interesting tubes to roll as drivers, I would suggest you take another look at your current holdings. If I am not mistaken you have a couple different 6H30-type power tubes that have recently been displaced by 6SN7s? :)

post #5639 of 8778

Hi Gibosi,

 

Are you suggesting that I try the 6N6P, 6N6P-i, 6N6P gold grid and 6N6P-IR as driver tubes? Didn't think of that. I seem to remember that AFB tried his 6H30-DR tube as a driver with good results.

 

Sounds interesting - I'll give it a shot when I finish burning in the 12V Westinghouse tube. Thanks,

post #5640 of 8778
Quote:
Originally Posted by mordy View Post
 

Hi Gibosi,

 

Are you suggesting that I try the 6N6P, 6N6P-i, 6N6P gold grid and 6N6P-IR as driver tubes? Didn't think of that. I seem to remember that AFB tried his 6H30-DR tube as a driver with good results.

 

Sounds interesting - I'll give it a shot when I finish burning in the 12V Westinghouse tube. Thanks,

 

Exactly! :)

 

As the 6H30-DR requires an external heater PS to be used as a driver, AFB was not able to try his... But I know he wanted to....

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