[OctavianH]

I mentioned several times that I do not know too much about my Philips PE06/40N with date codes KL/DUF. Well, one way to find more is to investigate also the PE06/40P which is the side contact version. I was lucky to find one piece in a bundle sale and now I am investigating its construction. A very beautiful and special tube, which should normally work on the EL50/51 -> 6V6 adapters because the pinout si similar, but well mine does not light up. It seems it's new, was NOS NIB as many love to buy, but does not work. However, this is not my major problem because I want more to find out about its origin than to listen to it because it looks identical inside with my N version.

This one has no code on the base, but has the J20 which seems to be a date code. Inside, except the base, everything seems identical. Even that "darker" glass I was mentioning at my N pair which is not "clear" glass as many others but not coated either. A very beautiful and noble looking tube about which I hope one day I will know more.

So NOS NIB tubes, all love them, in my case I prefer used ones, cheaper and about those we at least know they worked at a point in time.

 

[OctavianH]

Returning to these metal base tubes, I made a check of 5-code 4654 and 4654K and sound identical. Both types with flat ring getter. My pairs were 51/E42 and 54/P72.

So now I can store my 4654K and free a pair of EL39 adapters for other use. I was also not able to hear any differences between different getter types, so getter remains for me a sign of age more than a relevant component for sound quality, at least for these types of tubes. I have here disc getter, 2/3 disc getter or half-disc getters, then flat ring getters and even double-D getters if I remember correctly. Of course, you are more proud to use older types but in the end I think you cannot go wrong with any of these. Even if you buy singles and pair different types (K or non-K) you might obtain the same sound. The only difference I was able to hear was between 5-code and L-code. L-code were an idea more relaxed and bright, but of course, slight differences which might be in my head only. Anyway, I prefer to use them without mixing factory codes and if possible, with similar date codes. Glass shape is not perfectly identical in these, some have a flat top while others are rounded corners. I never observed sound differences. And of course, look on the base at the codes, never trust what your see printed of them: I have on the amp a pair of 4654 branded EL50 while I also have 4654K branded EL39. I also have ST shaped branded 4654 or EL50. So what's printed on them is just for looks in my view. Codes are stamped on base and that's all that matters.

 

[Isaacc7]

I am hoping I will have an answer to my amp issue this coming week. It’s so frustrating, I just need the amp moved to a table so i can open it up and check the internal fuses. It’ll happen soon.

In the meantime I have been listening to my other amp. It is quite nice but it really doesn’t match up to my Odyssey. On a whim I tried the Visseux 11n7 as the input again and it still doesn’t measure up to a 6sn7. The ecc31 is even more disappointing. My amps just aren’t set up for those to work at their best. Had a mad idea of getting some adapters made that would allow me to use either 6n7 or 6j5 like some of Tomas’s amps were made. I quickly set that idea aside. I have no idea if the paralleled triodes would sound good and I am already swimming with great sounding input tube options. No, it’s best I just put those tubes away. I can get some good money for the ecc31, don’t know who would buy the 11n7 though, except me lol.

 

[OctavianH]

I am hoping I will have an answer to my amp issue this coming week. It’s so frustrating, I just need the amp moved to a table so i can open it up and check the internal fuses. It’ll happen soon.

Sad to hear that, you do not have a family member or even a neighbor to ask for help?

In the meantime I have been listening to my other amp. It is quite nice but it really doesn’t match up to my Odyssey. On a whim I tried the Visseux 11n7 as the input again and it still doesn’t measure up to a 6sn7.

11N7 seems to me a 11V heater 6N7. 6N7 is in general warm but Visseaux are usually more neutral than the most of others. I have here a pair I think of Visseaux 6N7. They look like this:

6N7 is a very nice tube, I have a box of them here and I was not dissapointed by any of them. In Eternity I can use them without adapters in the 6J5 slots but since triodes are in parallel they have to be biased at 2mA and I have a feeling the 6N7 sounds better at 4mA in the 6SN7 slot. So I usually put them in that one with an adapter.

The ecc31 is even more disappointing. My amps just aren’t set up for those to work at their best.

Mine either, ECC31 and ECC32 sound close and honestly under many others. I have no idea in what amp those sound good, maybe those OTL...

Had a mad idea of getting some adapters made that would allow me to use either 6n7 or 6j5 like some of Tomas’s amps were made. I quickly set that idea aside. I have no idea if the paralleled triodes would sound good and I am already swimming with great sounding input tube options. No, it’s best I just put those tubes away. I can get some good money for the ecc31, don’t know who would buy the 11n7 though, except me lol.

6N7 can be found at good prices and you should find easily some RCA clear or grey glass. They sound very good. If you want to go cheaper you can also look at metal body ones. I have here some full metal RCA which is again, nice sounding. Do not ignore these.

Because I was unsure about the feasibility of the Old European Pentode Tribute Amp (wow, what a long name LOL) I thought about another possible one. So in fact I have ideas for 3 different tube amps, all built for different purposes somehow. Each of them is trying to solve some problems I had with Eternity. But since we speak about these let's mention them:
1) a SET amp from Eufonika with variable heaters on both stages. So you set whatever heater voltage in a range of let's say 0->25V and that's it. Wired of course for 6V6 and 6SN7 at least (if not also with single triodes wired as 6J5). This would be a classic design (not parafeed or anything) to have that tube flavour and problems of old designs. But I would like to have it with manual grid bias and I doubt Wieslaw builds something like this.
2) the old pentode tribute which became quite complex on the paper but it is not feasible for rolling because of these tubes which besides the socket do not really like to be rolled (for example EL50 or EL6 do not really like to be turned on/off too often so they have to be left on the amp the whole day to avoid problems).
3) last but not least, this one came after I started to study A1101 Audio thread and also read and discussed with more experience people about CCS and gyrators and so on. It's the most complex one, a kind of derived Solar Flare but with CCS and variable plate voltage. Basically I want to be able to bias at let's say 20mA / 40mA / 60mA and let the circuitry and CCS find an operating point by raising the plate voltage as high as needed for the tube to reach that current. In short, you just need to be sure that the tube can reach safely that current. Then you just set the bias point and put the tube. So I can bias let's say EL38 at 40mA and EL42 at 20mA or where I feel it's ok for these. But on top of this (and I am unsure if it makes sense in CCS context) I would like to also variate plate voltage at let's say 200V / 300V / 400V on output. So basically to move on both directions on the tube graph. And of course triode/ultralinear if possible and also SET/parafeed. And why not 1/2 stages selector and if possible input stage to be able to be used as a single amplifying stage in a kind of OTL mode. Of course, similar to output to have 1mA / 4mA / 8mA on input stage and 100V / 200V or something. So I can bias 6SL7 or 6N7 but also the low current high mu tubes properly. You know, all those 1mA 100 mu tubes like for example 6AT6 and others which failed on Eternity at 3-4mA. There are a lot of tubes like these which should sound phenomenal. As others said, nobody with brains would build this. LOL

So yeap, a lot of ideas. But I am mixing somehow gyrator loaded plates here with CCS tail. This last one is work in progress so I have some ideas but are not final and clear. I guess variable plate voltages are not needed, those work with gyrator loaded plates and it does not make sense to have constant current and also variable plate voltages. Tubes will raise as much as they need. It would be cool to know how this works for unmatched pairs for example. One goes to 180V and other to 220V? Any audible difference? We will see, I'll have to make a serious plan for 3) and then why not think if some of those ideas are not feasible also for 2). And then forget them and use Eternity because it is perfect for me. LOL