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2359glenn | studio - Page 768

post #11506 of 11519
Quote:
Originally Posted by whirlwind View Post
 

These beauties just arrived today, from a long journey from Italy

 

 

 

Glenn....make sure you make me an adapter so I can enjoy the goodness  :smile:


They have done allot of traveling.

OK I will make you a 6F8 adapter.

post #11507 of 11519

What about moving to a lower gain driver stage to control noise?  Design the driver stage for 6BL7 or 6BX7 this could bring the noise floor down without having to double the price of the amp from using exotic parts.

 

I thought the 5687 sounded good in the amp too, I think the mu on that tube is only 16.

post #11508 of 11519

Tequila brunch with Clayton...lots of guacamole for vitamins!

AppleMark

post #11509 of 11519
Quote:
Originally Posted by Xcalibur255 View Post
 

What about moving to a lower gain driver stage to control noise?  Design the driver stage for 6BL7 or 6BX7 this could bring the noise floor down without having to double the price of the amp from using exotic parts.

 

I thought the 5687 sounded good in the amp too, I think the mu on that tube is only 16.


The C3g might have to much gain for a OTL. In a amp with a output transformer any noise

from the high gain will be reduced by the ratio of the output transformer.

I a OTL what is there is right to the output.

Another tube is a 6AH7 round plate with a gain of 16. I think I gave you a adapter for these

I don't remember how they sound.

The circuit is not right to stick a 6BL7 in there he can try it the worst it won't sound good.

Parallel 6BL7 sound great as outputs puts all 6AS7 types to shame.  

post #11510 of 11519
Quote:
Originally Posted by parbaked View Post
 

Tequila brunch with Clayton...lots of guacamole for vitamins!

AppleMark

I had guacamole and chips for lunch but no Tequila

I am going to have to go to CA and hang with you guys you have to much fun.

post #11511 of 11519
Quote:
Originally Posted by 2359glenn View Post
 

I am going to have to go to CA and hang with you guys you have to much fun.

Doooiiiitt!!

 

We found a new dive bar after.

Bartender is a big time vinyl collector.

He liked Clayton so much that our tab was only$12...for 4 martinis! 

post #11512 of 11519
Quote:
Originally Posted by 2359glenn View Post
 

The C3g might have to much gain for a OTL....

 

As the Little Dot uses 6SL7s and 6080/6AS7, how is it that a gain of 60 isn't too high in that amp? 

 

Anyway, I can say that most of the 6080s are very quiet with the C3g, especially the slotted Bendix 6080, which is my current favorite. But the primary reason I wanted this amp is to roll lots of tubes, in addition to SN7 and C3g. As I have mentioned before, I am rolling 5687, 6350, 6463, ECC40, E80CC/6085, E182CC/7119, E88CC/6922/6N23P, BL63/VR102 and even some of the sub-miniatures. And as these are all medium-mu double triodes, they all sound great with almost every output tube.

 

Again, I am very pleased with this amp. And it's kind of neat to have a one-of-kind, the only OTL with the original transformer and the C3g, a "prototype" if you will.... I feel very lucky to have it. :)

 

A Sylvania sub-miniature very crudely stuffed into an octal base

 


Edited by gibosi - 4/26/15 at 4:58am
post #11513 of 11519
Quote:
Originally Posted by gibosi View Post
 
Quote:
Originally Posted by 2359glenn View Post
 

The C3g might have to much gain for a OTL....

 

As the Little Dot uses 6SL7s and 6080/6AS7, how is it that a gain of 60 isn't too high in that amp? 

 

Anyway, I can say that most of the 6080s are very quiet with the C3g, especially the slotted Bendix 6080, which is my current favorite. But the primary reason I wanted this amp is to roll lots of tubes, in addition to SN7 and C3g. As I have mentioned before, I am rolling 5687, 6350, 6463, ECC40, E80CC/6085, E182CC/7119, E88CC/6922/6N23P, BL63/VR102 and even some of the sub-miniatures. And as these are all medium-mu double triodes, they all sound great with almost every output tube.

 

Again, I am very pleased with this amp. And it's kind of neat to have a one-of-kind, the only OTL with the original transformer and the C3g, a "prototype" if you will.... I feel very lucky to have it. :)

 

A Sylvania sub-miniature very crudely stuffed into an octal socket

 


You tried all those tubes?

There are lots of them out there with that power transformer. I still have one of those transformers left to go in a amp 

post #11514 of 11519
Quote:
Originally Posted by 2359glenn View Post

 

You tried all those tubes?

 

 

Yep, and I can verify that they all sound very good in your amp. The appropriate pin-adapters are cheap and there are some very nice alternatives to SN7 out there.

post #11515 of 11519
Quote:
Originally Posted by 2359glenn View Post
 


The C3g might have to much gain for a OTL. In a amp with a output transformer any noise

from the high gain will be reduced by the ratio of the output transformer.

I a OTL what is there is right to the output.

Another tube is a 6AH7 round plate with a gain of 16. I think I gave you a adapter for these

I don't remember how they sound.

The circuit is not right to stick a 6BL7 in there he can try it the worst it won't sound good.

Parallel 6BL7 sound great as outputs puts all 6AS7 types to shame.  

 

I mean actually design the circuit specifically for the 6BX7.  This tube or the 5687 might work well in an optimized circuit.  I thought it sounded pretty good running on a 6SN7s values even.  These tubes are cheaper than the "best" 6SN7s too.

 

I've come to believe it's really not wise to judge a tube running in a circuit that wasn't actually designed specifically for it.

 

I recall not liking the sound of the 6AH7 very much.  I can try it again.  Maybe the same feeling as above applies here too.  If the circuit were designed for it maybe it would sound good.  Lots of what ifs, but there might be a very successful combination out there waiting to be discovered still.

post #11516 of 11519
Quote:
Originally Posted by gibosi View Post
 

 

Yep, and I can verify that they all sound very good in your amp. The appropriate pin-adapters are cheap and there are some very nice alternatives to SN7 out there.


7119 is a variant of the 5687 if I recall correctly, and there are a couple of other close variants also.  I like the 5687 the most out of that particular family of tubes because it has the lowest gain.  These are tubes from the Apollo space era, much better distortion and overall performance compared to stuff like the 12AX7.  I'm really confused why they are not used in more designs.

post #11517 of 11519

I have been using the GEC 6080's and one just gave up

the ghost and not even a year old. Anyway just wondering

what to do with the existing tube that is still good? I really

liked the sound of these tubes but I just don't know how to

proceed. Any ideas would be appreciated. Thanks


Edited by rnadell - 4/26/15 at 4:13pm
post #11518 of 11519

Buy a single replacement tube and continue to use the other good one.  If the original pair tested strong than any reasonable strong tube will work fine with it, it won't have lost that much emission in a single year of use.

 

When my 5998 shorted (taking my headphones with it) Glenn got me a new single tube and I just plopped it in and couldn't tell the difference.

post #11519 of 11519
Quote:
Originally Posted by Xcalibur255 View Post
 

7119 is a variant of the 5687 if I recall correctly, and there are a couple of other close variants also.  I like the 5687 the most out of that particular family of tubes because it has the lowest gain.  These are tubes from the Apollo space era, much better distortion and overall performance compared to stuff like the 12AX7.  I'm really confused why they are not used in more designs.

 

The 5687, 6900, 7044 and 7119/E182CC all share the same pin-out and were all developed to meet rather severe operating conditions often found in industrial/military operating environments. As such they were not typically used in the consumer market. But other than this, I am not sure how closely these tubes are related.

 

The 5687 has a gain of about 16, the 6900, a gain of about 18.5, the 7044, a gain of 21, and the 7119, a gain of 24. 

 

Used in the 6.3 volt mode (excepting the 6900, these can also be used in 12.6 volt circuits) the 6900 heaters draw 1.0 amp and the 5687 and 7044, 0.9 amp, so these are hot little guys. On the other hand, the 7119 draws 0.64 amps, similar to a 6SN7.

 

The 6900 was manufactured only by Bendix and given their rarity and supposed durability, these often go for several hundred dollars each, and thus, I do not have one, and likely never will.

 

The 7119/E182CC was manufactured only by Philips, primarily in their Heerlen, Holland, factory. In the early 1970s, production was shifted to the Amperex factory in Hicksville, NY. Based on the nomenclature, some speculate that this tube was conceived and designed to be an ultra premium, 10,000-hour 12AU7/ECC82. For example, the 7308/E188CC is an ultra premium 6DJ8/ECC88. While this seems to makes sense, I do not know if it is true.

 

As best as I have been able to tell, the 7044 was manufactured only by Sylvania, GE and RCA.

 

The 5687 has the most variety, manufactured by Tung-Sol, RCA, Sylvania, GE and Raytheon in the the US, and Thompson CSF in France.

 

In my Little Dot, I didn't much care for the 7044, but can no longer remember exactly why. Of the 5687, I preferred the Sylvania. But of all, I liked the 7119 best, especially the New York tube.

 

To date, I have rolled the 7119 and the Sylvania 5687 in the Glenn OTL for a short time, and my feeling is these tubes sound much, much better than in the LD. But of course, the operating points in the LD are much less optimal. Anyway, it will take some time to roll through all these tubes again to figure out how I might rank them....

 

I hope someone finds this useful and interesting. Even though the Glenn OTL was not specifically designed to use these tubes, they perform quite well, and in my opinion, are very worthy alternatives to the SN7 and the C3g.

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