[Isaacc7]

TR/UL is something interesting I would like to try.

By the way you said you buy some headphones to try on your Odyssey? What have you chosen?

Headphones have been put on hold for the moment. The only reason I was thinking about getting some was so I could monitor my sound experiments with a synth setup. I would mostly be using them with an audio interface not my main system. I would of course try them with odyssey but I can’t imagine that I would ever prefer using headphones for music.

 

[Isaacc7]

TR/UL is something interesting I would like to try.

By the way you said you buy some headphones to try on your Odyssey? What have you chosen?

UL really does change the sound as compared to triode. One of the highlight features is extra power compared to triode and I’m not sure how important that is with headphones.

I’m also not sure if it’s a good idea to do tube rolling with different types of tubes between triode and ultra linear if you can’t also adjust voltage and or bias. Both pentode and ultralinear modes have lots of possibilities for fireworks if the screen grid is overloaded.

The more I think about it the more I think Tomas was crazy to build my amp lol. No sane builder would give his customer so many ways to blow things up. Luckily for me he was as crazy as I am

 

[triod750]

That he built it anyway shows his respect for you.

 

[Isaacc7]

That he built it anyway shows his respect for you.

I think he relished making a really different amp. The circuit design is actually much simpler than the others he made but the features are unique. Dunno if respect is the right word, I think he was relieved to be finished with it lol. Pretty sure mine was the last amp he delivered

 

[OctavianH]

He built a lot of very different amps, but as far as I know he made only 2 with adjustabile manual grid bias: the two Eternity. Well, except yours which is unique from many ways. I was lucky to get one of these. There was also an Infinity with tube rolling add-on but I guess that the output stage was adapted to Odyssey and manual bias remained on input stage. He was a lot ahead of its time with these amps, I still discover and learn about them.

For me one feature I am really unsure about is the gain switch. Powerwise it has to be 3x, but whenever I listen to a headphone on high gain for me sounds more or less the same, an idea louder and smoother. So 99% I keep my headphones on low gain.

 

[Isaacc7]

He built a lot of very different amps, but as far as I know he made only 2 with adjustabile manual grid bias: the two Eternity. Well, except yours which is unique from many ways. I was lucky to get one of these. There was also an Infinity with tube rolling add-on but I guess that the output stage was adapted to Odyssey and manual bias remained on input stage. He was a lot ahead of its time with these amps, I still discover and learn about them.

For me one feature I am really unsure about is the gain switch. Powerwise it has to be 3x, but whenever I listen to a headphone on high gain for me sounds more or less the same, an idea louder and smoother. So 99% I keep my headphones on low gain.

I had asked about adjustable bias for the input tubes and he basically said that there was enough adjustments already lol. I think we had run out of space. I’m actually gfateful for the plug and play aspect. I go plenty crazy with the moving parts I have, adding another would send me right over the edge of insanity!

 

[OctavianH]

I had asked about adjustable bias for the input tubes and he basically said that there was enough adjustments already lol. I think we had run out of space. I’m actually gfateful for the plug and play aspect. I go plenty crazy with the moving parts I have, adding another would send me right over the edge of insanity!

I think in my case when I'll try the 6AT6 at 2.5mA, to have some direct control there is useful. That would be only an experiment, I want to get the full Oblivion experience (6AT6 + EL81). I'll also try some other interesting stuff soon, I was bored and bought some tubes, of course in 3-7 EUR/ piece range, so those will definitely be some audiophile grade ones.

 

[OctavianH]

What we have here? The infamous EL85, follower of EL42 and in theory electrically similar (I am afraid to say the same). Look at these beauties.

Even that blue "foot" on them with Mullard logo, pristine condition. Nobody cares about these so I found them NOS NIB.
Date codes:
- for Philips branded ones: rW2/B5J3 (the other one J4)
- for Mullard branded ones: 660/R5E

More details:

I am really excited to measure these, so more will follow soon.

 

[OctavianH]

Now, R=Mullard Mitcham and B=Mullard Blackburn. But why rW and 66? My Philips manual tells me:

and

What means EL85 min compared to EL85 I have no idea. What I can say is that these bias in the same way and for me around -10V for 200V/20mA.
About how these sound or if these can be compared to EL42, we will see in some weeks. At first listen of the Mitcham pair, definitely not at the point of having a coherent opinion, I can say that these are not so analogue and relaxed as EL42, but they have exceptional bass and very good sound. I like a lot what I hear but it is not for me what I was expecting on EL42. No problem, actually this is an advantage, I have enough EL42 and needed something different. A noval pentode with lower gain than EL83/84 and this sound is always a good part of my collection. So, welcome EL85 among my EL81, EL83 and EL84. And yeap, we miss EL82? Right, so stay tuned. EL82 will come soon in our attention. For now let's take some care about EL85.

Measurements for 200V/20mA:

As measurements were showing the Mitcham ones are an idea not matched but well enough in my usable range (3mA between):

 

[TLO]

Now, R=Mullard Mitcham and B=Mullard Blackburn. But why rW and 66? My Philips manual tells me:

and

What means EL85 min compared to EL85 I have no idea. What I can say is that these bias in the same way and for me around -10V for 200V/20mA.
About how these sound or if these can be compared to EL42, we will see in some weeks. At first listen of the Mitcham pair, definitely not at the point of having a coherent opinion, I can say that these are not so analogue and relaxed as EL42, but they have exceptional bass and very good sound. I like a lot what I hear but it is not for me what I was expecting on EL42. No problem, actually this is an advantage, I have enough EL42 and needed something different. A noval pentode with lower gain than EL83/84 and this sound is always a good part of my collection. So, welcome EL85 among my EL81, EL83 and EL84. And yeap, we miss EL82? Right, so stay tuned. EL82 will come soon in our attention. For now let's take some care about EL85.

Measurements for 200V/20mA:



As measurements were showing the Mitcham ones are an idea not matched but well enough in my usable range (3mA between):

Hmmm...I thought R is Ferranti n D is Mitcham.

 

[Wes S]

Hmmm...I thought R is Ferranti n D is Mitcham.

You are right during the 40's, and then it changed in the 50's.

 

[OctavianH]

Hmmm...I thought R is Ferranti n D is Mitcham.

I look here:

 

[Wes S]

I look here:

Look here https://mullard.org/blogs/news/83886851-cv-numbers-and-uk-military-date-and-factory-codes

 

[OctavianH]

Look here https://mullard.org/blogs/news/83886851-cv-numbers-and-uk-military-date-and-factory-codes

Yeap I know it too. I'll look on both.

By the way both pairs of EL85 have "Import" on it. Philips branded ones with B-code have it, but also Mullard with R-code have it. Why? From where was importing Mullard this tube? Mullard ones have those blue boxes while Philips ones have yellow boxes.

 

[OctavianH]

And a photo of them in action with the new aluminium adapters from Deyan.

I avoid to say something, but these do not sound to me as Mullards, tight bass, quite fast, less euphonic. I'll have to dig on these more to find out what's happening. I'll put later the Blackburn pair just to see if those remind me of EL42 Blackburn or are in the same way as these.

Later edit: I find these that type of "modern" tube sound. But with mu around 10 are between EL83/84 and EL81 as energy. I like this kind of moderated energetic sound and this goes well with 6SL7. EL82 should be in the same mu range so I have quite big expectation from those. EL83/84 are an idea too much for me, sounding quite on steroids and while I liked a lot Telefunken EL803 (that clean speedy sound goes well with Telefunken signature) I always felt they are an idea to much. It seems the middle ground of EL85 sounds good and more energetic than EL81. But still, the modern sound, not EL41/42 analogue retro feeling. Those remain unique. We'll see more when putting the B-code pair.