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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 125

post #1861 of 7513
Quote:
Originally Posted by bruce108 View Post

On the Telefunken EK90s. At first, mine were not so much treble-forward as bass-light and overall a bit thin-sounding, if refined and musical (EF95). But after 40-50 hrs they became a dramatically different tube, excellent bass in quantity and quality and well-balanced through the FR. Here's the thing: they warm up more slowly than any of my other tubes, taking an hour or so to reach their optimum. Any technical reason for this?

 

I probably don't have more than 30 hours on mine, but even so, I don't find the bass to be light on these at all. Out of curiosity, I also compared them to the Telefunken EH900S (I have about 25 hours on these). Both of these tubes share the same house sound and have a very similar tonality. And most noticeably, unlike AFB, I do not find the EH900S to be any more forward than the EK90. I wonder why? My EH900S do not have gold pins... Maybe those with gold pins are actually different?

post #1862 of 7513
Quote:
Originally Posted by bruce108 View Post

On the Telefunken EK90s. At first, mine were not so much treble-forward as bass-light and overall a bit thin-sounding, if refined and musical (EF95). But after 40-50 hrs they became a dramatically different tube, excellent bass in quantity and quality and well-balanced through the FR. Here's the thing: they warm up more slowly than any of my other tubes, taking an hour or so to reach their optimum. Any technical reason for this?
 


So, I'm good for yet another 50 hour burn-in huh...? The things we do for music...

 

While I definitely noticed that they improve after a bit of warm-up time -most tubes do to some extent- I have haven't noticed anything as dramatic as a whole hour. I guess it's possible though, I remember thinking that even my old stock M8100 needed 15-20 minutes to sound their best.

 

Again, I find it pretty difficult to directly compare these heptodes together, and find myself forced to compare "lasting impressions" instead, which I usually do fairly well, but isn't exactly a fail-safe method. The fact that everyone here has different impressions of the Telefunken EH900S (regardless of gold pins, as I just saw that A11's have them and gibosi's don't, yet same comments) does strike me as odd -as in my impressions being off.

 

I had tested and burnt-in the Tele EH900S with the 1-7 strap until the very end, when I tried them unstrapped and concluded that was best; so, that probably influenced my impressions in and of itself (the tubes really were quite "in your face" when strapped, and I'm now pretty sure that needed way more than the 20 hours of burn-in I gave them anyway; most premium tubes do apparently). The fact that everyone says the EH900S (6BY6) and EK90 (6BE6) Telefunken are similar makes me think that they, indeed, are -which would make perfect sense as they look similar anyway- and that I just need to eventually throw the EH900S back in the sockets to confirm that. I will, at some point, after the 40h burn-in...

 

I do like that hard-hitting bass (not strong, just intense and punchy) on the Tele EK90 though. I still have some serious comparing to do with all those other German heptodes. Another German shootout?

post #1863 of 7513
Quote:
Originally Posted by Acapella11 View Post

Elektronenroehre

Siemens AG Muenchen 80

 

The fact that there is no German "ö" but "oe" instead points further to not one of the regular German productions.

 

I think this rather points to limited character sets of early computers.

post #1864 of 7513
Quote:
Originally Posted by MIKELAP View Post

Processed By eBay with ImageMagick, R1.1.1.M2b

 

I haven't seen the name Svetlana mentioned. That's what we have here. Note the =C= logo.

post #1865 of 7513
Quote:
Originally Posted by Audiofanboy View Post


So, I'm good for yet another 50 hour burn-in huh...? The things we do for music...

 

While I definitely noticed that they improve after a bit of warm-up time -most tubes do to some extent- I have haven't noticed anything as dramatic as a whole hour. I guess it's possible though, I remember thinking that even my old stock M8100 needed 15-20 minutes to sound their best.

 

Again, I find it pretty difficult to directly compare these heptodes together, and find myself forced to compare "lasting impressions" instead, which I usually do fairly well, but isn't exactly a fail-safe method. The fact that everyone here has different impressions of the Telefunken EH900S (regardless of gold pins, as I just saw that A11's have them and gibosi's don't, yet same comments) does strike me as odd -as in my impressions being off.

 

I had tested and burnt-in the Tele EH900S with the 1-7 strap until the very end, when I tried them unstrapped and concluded that was best; so, that probably influenced my impressions in and of itself (the tubes really were quite "in your face" when strapped, and I'm now pretty sure that needed way more than the 20 hours of burn-in I gave them anyway; most premium tubes do apparently). The fact that everyone says the EH900S (6BY6) and EK90 (6BE6) Telefunken are similar makes me think that they, indeed, are -which would make perfect sense as they look similar anyway- and that I just need to eventually throw the EH900S back in the sockets to confirm that. I will, at some point, after the 40h burn-in...

 

I do like that hard-hitting bass (not strong, just intense and punchy) on the Tele EK90 though. I still have some serious comparing to do with all those other German heptodes. Another German shootout?

 

I think I like the EK90 with the 7-1 strap since it adds some brightness to my HD650's which are relatively dark. I know you've said before the 7-1 on the EK90 for you was too fatiguing for you, which headphones are you using?

 

I also ordered a pair of the 1680's curious to see how earlier variants sounded.


Edited by mab1376 - 7/11/13 at 4:45am
post #1866 of 7513
Quote:
Originally Posted by mab1376 View Post

 

I think I like the EK90 with the 7-1 strap since it adds some brightness to my HD650's which are relatively dark. I know you've said before the 7-1 on the EK90 for you was too fatiguing for you, which headphones are you using?

 

I also ordered a pair of the 1680's curious to see how earlier variants sounded.


Nope, never tried the 1-7 strap on a 6BE6 type, only on 6BY6 types, where I do find the setting often a bit too treble-centric.

 

I'm using HifiMAN HE-500 headphones, which is quite silly with an OTL tube amp, but works great, oddly enough. Some would say these are neutral, but they do have a hump or two in the upper mids and treble; so, while it's hard to make them "fatiguing", it is easy to make them a bit too treble oriented, or too detailed essentially.

 

I'm sure you'll like the 1680, they're interesting tubes; and as gibosi pointed out, it is quite amusing to know you're using almost "historical" tubes, that were basically made for "vacuum tube computers". Makes for great small talk when have people over lol (that, and the USSR power tubes)!

post #1867 of 7513
Quote:
Originally Posted by Audiofanboy View Post


Nope, never tried the 1-7 strap on a 6BE6 type, only on 6BY6 types, where I do find the setting often a bit too treble-centric.

 

I'm using HifiMAN HE-500 headphones, which is quite silly with an OTL tube amp, but works great, oddly enough. Some would say these are neutral, but they do have a hump or two in the upper mids and treble; so, while it's hard to make them "fatiguing", it is easy to make them a bit too treble oriented, or too detailed essentially.

 

I'm sure you'll like the 1680, they're interesting tubes; and as gibosi pointed out, it is quite amusing to know you're using almost "historical" tubes, that were basically made for "vacuum tube computers". Makes for great small talk when have people over lol (that, and the USSR power tubes)!

 

BTW The ones I ordered are: 1680 IBM 6BE6 Vacuum Tube marked 1680, 6B3001, 303613 code dated 0-04 or 0-13 , 274 meaning 1950 the 13th week.

post #1868 of 7513

Hi MAB 1376,

 

The ones I got have the same information as yours, but date codes 0-09 and 3-22 which I think means 9th week 1950 and 22nd week 1953.

 

274 stands for Radio Corporation of America - RCA

 

Look, for $3 each + $1.69 shipping you cannot go wrong.
 

post #1869 of 7513
Quote:
Originally Posted by Acapella11 View Post

Siemens EK90 (6BE6): black bottom, no logo, saucer getter, 4 extended square holes at bottom and top front at back of tube, 02/78

These should be the of the same type as hypnos1 has. They were from here but are not listed anymore.

 

Those could be Svetlanas, too. I see plenty of similarities. Certainly of USSR origin.

 

Siemens EH90 (6CS6): halo getter, 4 extended square holes at bottom and top front at back of tube, 06/78

 

The octagonal box around the type code is not typical for Siemens and, I wonder, foreign to which market.

 

I'd expect a Siemens-made tube to have an etched code like Philips-made tubes, or later on a piece of metal embossed with 4 characters inside the tube.

 

Siemens made tubes in Munich but obviously also labeled tubes made by others, especially towards the later tube era.

post #1870 of 7513

Is it possible that these tubes are the "FOREIGN" manufacturer of the Siemens EH90 678 tubes? Take a look at the various pictures in this ad:

 

http://www.ebay.com/itm/TESTED-Russian-6A2P-GEPTODE-tube-6BE6-EK90-6H31-X77-NOS-10-pcs-/310700109772?pt=LH_DefaultDomain_0&hash=item48572b6fcc

post #1871 of 7513
Quote:
Originally Posted by mordy View Post

Is it possible that these tubes are the "FOREIGN" manufacturer of the Siemens EH90 678 tubes? Take a look at the various pictures in this ad:

 

http://www.ebay.com/itm/TESTED-Russian-6A2P-GEPTODE-tube-6BE6-EK90-6H31-X77-NOS-10-pcs-/310700109772?pt=LH_DefaultDomain_0&hash=item48572b6fcc

 

I believe that Russian EH90s typically had saucer getters, whereas A11's tubes have halo getters. However, I can't quite make out from the photos whether these Russian tubes have saucer or halo getters?

 

I should also note that I seriously doubt that the three digit number is the date of manufacture. One of my Siemens EH90 has the three-digit code 201. Manufactured in February '01? lol It is my understanding that these codes are some sort of "batch" code that had some meaning within the factory, perhaps something similar to the "change" code within Philips factories.

 

It is known that Siemens closed their Munich Halske factory in 1971 and transferred all production to somewhere in Eastern Europe. So my best guess is saucer getters indicates Easter Europe. Halo getters? If not Munich, then where? If Philips, I think we should see a standard Philips tube code, but none are visible on A11's tubes.... 

post #1872 of 7513
Quote:
Originally Posted by Oskari View Post

I'd expect a Siemens-made tube to have an etched code like Philips-made tubes, or later on a piece of metal embossed with 4 characters inside the tube.

 

Siemens made tubes in Munich but obviously also labeled tubes made by others, especially towards the later tube era.

 

These etched codes are apparently standard on their dual triodes, but not on all their tubes. I have used a magnifying glass to scrutinize my Siemens EK90 and EH90, two different pairs each, all with the Siemens/Halske logo, and can find no codes of any kind, on the glass or inside.

post #1873 of 7513

Let's try this:

 

Go to the Ebay ad again, and look at the pictures. On the left is a slider; pull it down, and there is one more picture there. Using the CTRL button and the scroll wheel on the mouse, blow up the picture. Then use the Mouse Here To Zoom In feature and look carefully at the getter. IMHO it is a circular getter. (The third picture blown up also supports this.) The ribbing of the plate looks like the Siemens tube.

 

If this indeed is it, we have a cheap supply of ersatz Siemens tubes....
 

post #1874 of 7513

About the date code: Perhaps it is logical that 678 refers to August 1967 or 8th week 1967?

 

About the 201: Somewhere on this blog I saw a post that the box AND the tube had a unique number, such as 201.

post #1875 of 7513
Quote:
Originally Posted by mordy View Post

About the date code: Perhaps it is logical that 678 refers to August 1967 or 8th week 1967?

 

About the 201: Somewhere on this blog I saw a post that the box AND the tube had a unique number, such as 201.

 

I have two different pairs of Siemens EH90, one with a three-digit code of 201, and the other, 271. And yes, in each case, this number is also printed on the corresponding box. So if 271 implies 1971, what does 201 imply?

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