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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 146

post #2176 of 8461

Hi Mikelap,

 

Re the Siem EH90s, I am one lap ahead of you cause I am nearing the 35 hr mark. In all seriousness, and in the interest of scientific exploration, did you try the 2/7 strap yet? (Did not yet try it myself)
 

post #2177 of 8461

Hi All,

 

Here is a review of the Sylvania 6CS6 (EH90) tube after appr 60 hours of burn in. (Once I was in a shoe store Midwest and saw a sign that said: "Near Pair".  Apparently, somebody had sold someone 2 different sizes, and what was left was a 7 and a 71/2; thus "near pair." )

The Sylvanias are both 6CS6, but the etching of the designation is a little bit different on the two tubes. Likewise, the boxes are slightly different in color. The tubes otherwise look the same, and sound the same. My assumption is that they can be viewed as a pair, but from two different production runs. Take a look:

 

 

 

 

 

It was a challenge to find a pair at a good price, but ended up paying less than $6 for the pair, including shipping. Was not able to decipher the dates, but it is safe to say that the tubes are from the 50's-60's.

 

In my 18 months odyssey to find the perfect 6AK5 tube I learned a lot of things. My conclusion about "house sound" is that there are "house traits" instead. The Sylvanias stood out as the sound stage champions. These 6CS6 tubes have the widest sound stage I've heard so far.

 

I have a recording with a clarinet and banjo solo. Most tubes place the banjo on the right, and the clarinet in the middle, which makes this very nice recording annoying to listen to. It's like half a sound stage. These tubes place the banjo outside the speakers on the right, and the clarinet all the way to the left. Amazing.

 

Now for listening impressions: EF95 1/7 and 2/7 - nothing special; mid range OK, lacking in rhythm and pace. 

 

EF 92 (done on EF95 6/7 setting): Quite good bass, mid range, rhythm and pace, but too skewed towards the treble; too sibilant on many recordings.

 

EF95 NS (no strap-plug and play): This is it! Viva la Heptode! Excitement, musicality, good rhythm, pace and timbre. Very good bass with excellent slam and attack, but not the deepest bass.Brings out the essence of the music without excessive analytical detail. Superb instrument separation and imaging. Mid range very good, treble detailed.

 

Cons: The tubes are very sensitive to the recording quality, and you immediately hear the differences in the recording venue. There is a peculiar and curios ability to overdose on the treble on certain bright recordings, making them unpleasant to listen to. Can't figure out what level of treble or type of recording triggers this response.

 

Summary: Not the ultimate in bass and treble presentation, but very pleasant, warm, musical tubes with a full bodied sound with an enormous sound stage. Recommended.

post #2178 of 8461
Quote:
Originally Posted by mordy View Post

 
A curiosity - did anybody else notice this? After changing jumper settings sometimes the first impression is forget it - does not sound good. If you leave the tubes on an hour or two on that setting and listen again, suddenly they sound much better. It as if the tubes need time to settle in into the new environment to come to their full potential.

I heard that people who grow flowers talk to them. Maybe I should talk to mine to make them sound better after they have been replanted? atsmile.gif

This is interesting. I could swear I've heard a similar thing happen with a number of tubes. Whatever I *might* be hearing, apparent in the bass section. I also seem to think that there's a sweet spot between the tubes not having been on long enough and then having been on for too long.
I've been wondering if I'm insane. Some times it seems like the issue doesn't happen at night, far more toe tapping happens then for me. Maybe it's some sort of electrical interference caused during the day?

Maybe it's time I go see a doctor...
post #2179 of 8461
Quote:
Some times it seems like the issue doesn't happen at night, far more toe tapping happens then for me. Maybe it's some sort of electrical interference caused during the day?

 

That's maybe your power supply: the more people using the grid, the dirtier the domestic power. Late night is definitely better here on whatever equipment.
 

post #2180 of 8461

Hi inphu510n,

 

There is nothing wrong with you. (Don't waste money on a doctor visit!) During the day there is a lot of electrical interference from various lights, appliances, portable phones etc. This produces electrical grunge (RF interference) that has an impact on the sound.

 

As mentioned, these things tend to be happening much less at night, and the sound improves.

 

As also mentioned, an A/C line conditioner from a reputable manufacturer will filter out a lot of these kinds of noises, and you will notice a "blacker" background when listening. (Just don't go overboard and spend more than the amp cost...)

 

Regarding the tubes sounding better after being warmed up - I think that there is universal agreement on this. Some tubes take longer than others, but my guess is that 1/2 to one hour should bring any tube up to maximum performance once they are burnt in. If you change settings, my experience is that some tubes may need about two hours to "settle in."

 

About tubes getting "tired" I am not sure that there is agreement on this. From what I read some people felt that tubes sounded better after being on for prolonged periods.

 

All I know is that after trying to analyze the subtle differences between different heptodes and different settings I am getting tired....
 

post #2181 of 8461
Quote:
Originally Posted by mordy View Post

Hi Mikelap,

 

Re the Siem EH90s, I am one lap ahead of you cause I am nearing the 35 hr mark. In all seriousness, and in the interest of scientific exploration, did you try the 2/7 strap yet? (Did not yet try it myself)
 

Did not try 2-7 so far i think i mentionned EF95 1-7 was the setting for me but will check that out later forgot to try that one thanks mordy 

post #2182 of 8461
Quote:
Originally Posted by mordy View Post

All I know is that after trying to analyze the subtle differences between different heptodes and different settings I am getting tired....
 

 

+1 Sometimes it is easy to discriminate differences, sometimes it is difficult. Depends on daily form as well. Then, once you have got your impressions sorted you try strapping tubes you haven't strapped yet and it starts over on a slightly easier level. :) The next challenge after pinning down differences is prioritization...

 

After making notes to a quite a few tubes, I already listed the Svetlana 6A2P on the lowest rank. Now, after further burn in and strapping (1/7 or 2/7), I have to reconsider it seems. Another underrated tube for me is the Brimar CV4012 (non-strapped). Specifically after 30 h burn in... The Siemens EH90 Foreign didn't come out as high as I expected but I will tire myself a little more to pin it down... ;)

post #2183 of 8461
Quote:
Originally Posted by MIKELAP View Post

Did not try 2-7 so far i think i mentionned EF95 1-7 was the setting for me but will check that out later forgot to try that one thanks mordy 

 

 

Quote:
Originally Posted by mordy View Post

Hi Mikelap,

 

Re the Siem EH90s, I am one lap ahead of you cause I am nearing the 35 hr mark. In all seriousness, and in the interest of scientific exploration, did you try the 2/7 strap yet? (Did not yet try it myself)
 

I tried the EF95 2-7 setting not as clean sounding as EF95 1-7 setting but theres more bass warmer sounding in general i like that setting also . not much to hate all in all  . Buena note signor Mordicci 

post #2184 of 8461

Hi Mikelap and A11,

 

What makes the heptodes so challenging is the enormous amount of time you need for the tubes to burn in and stabilize; then all the different possibilities of no strap or strapping; and THEN, you got to give each setting a couple of hours to show it's true colors.

 

After all that, you have to decide which setting is best for you. So far I have now way of predicting what it will be. Then, for a tired old mind to try to remember which setting is the favorite one. I can't remember, so I write it down on a post-it note that I affix to the tubes or tube boxes with a rubber band.
 

Time for a break: (From reading the posts I know that some members like photography.) Up til now I did not know that frogs can beautiful. Lucked out with this picture. (Note the contended philosophical look - must come from enjoying listening to heptodes, or maybe eating bugs.) Do the double click to get a full size pic.

post #2185 of 8461
Quote:
Originally Posted by mordy View Post


I do hope you meant "heptoads" smily_headphones1.gif
post #2186 of 8461
Quote:
Originally Posted by mordy View Post

Hi Mikelap and A11,

 

What makes the heptodes so challenging is the enormous amount of time you need for the tubes to burn in and stabilize; then all the different possibilities of no strap or strapping; and THEN, you got to give each setting a couple of hours to show it's true colors.

 

After all that, you have to decide which setting is best for you. So far I have now way of predicting what it will be. Then, for a tired old mind to try to remember which setting is the favorite one. I can't remember, so I write it down on a post-it note that I affix to the tubes or tube boxes with a rubber band.
 

Time for a break: (From reading the posts I know that some members like photography.) Up til now I did not know that frogs can beautiful. Lucked out with this picture. (Note the contended philosophical look - must come from enjoying listening to heptodes, or maybe eating bugs.) Do the double click to get a full size pic.

That same day!

post #2187 of 8461

Я вижу, что я в хорошей компании.
 

post #2188 of 8461
أرى أنني في شركة جيدة.
biggrin.gif
post #2189 of 8461

みんな、今日は :)

 

I received an interesting package today. Recently, I came across a listing for some 6HZ6 tubes, and after a little research, decided to order a few. Found 7 tubes for $8 including shipping, two pairs, Sylvania and GE, and three singles, an extra GE, an RCA and a Mullard. However, the Mullard wasn't in the package... :(  I have contacted the vendor, but still, cheap. :)

 

I am inclined to describe these as "heptode wannabe pentodes" lol. They were used as FM sound detectors, and thus have two control grids, 1 and 3, plus a screen grid. So theoretically, we can treat these the same way we are currently treating heptodes: unstrapped EF95, EF91/92, and strapped 1-7 and 2-7. Apparently, there are no premium versions available and there is no European number. Since I don't have the Mullard in hand, it is unclear if it was manufactured by Mullard, or just a rebrand. Other than Mullard, I have seen only American brands on eBay. The Sylvanias are burning in unstrapped EF95, and I can tell you that they light up and play. (....a huge sigh of relief.... :)

 

http://www.radiomuseum.org/tubes/tube_6hz6.html

 

http://www.shinjo.info/frank/sheets/049/6/6HZ6.pdf

 

 

post #2190 of 8461
Quote:
Originally Posted by mordy View Post

Я вижу, что я в хорошей компании.
 

 

Он является одним из с вселенной

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