[OctavianH]

I paired the RCA 9002 with Tesla 4654. Good sound but these cannot match the sound of the Philips ones. More sterile (or less rich) and brighter. But very dynamic and transparent. A good tube, Tesla never ceases to impress me. Also the EL34 they made were very good. Same for EL81.

 

[triod750]

They look good too...

 

[OctavianH]

They look good too...

They look nice and sound nice, but still cannot compare with Philips. I have several getter types and also different construction. These are from 60s, I have a pair from 50s which look even better. But the older pair does not have the same glass size, so I am again like with EL11, it's hard to find 2 identical ones.

I will show, here is a ring getter one:

This one has a different getter:

The ones I call older (50s) are a little bit more beautiful and different on top:

But the pair I have, even if they look identical, one has bigger glass than other. These can be easily recognized by the top connection which has a different shape than for the others.

Now, regarding date codes, if these Tesla tables are right:
CU= Jun 1961
RS= Nov 1959
BU= Feb 1951
BT= Jan 1951
So you drag your own conclusions. Nevertheless, very nice tubes. Too bad are really hard to find and some sellers are asking wrong prices.

While I consider these inferior to the Philips ones, which are also much older, I like a lot how dynamic and clean they sound. A lot of slam, like on all EL50/51 (ST shaped). Tesla has a better extension on highs, so it sounds sharper and very detailed. Philips is more rich but also polite, sometimes blunt. It all depends on the whole chain synergy.

 

[OctavianH]

This newer construction of Tesla 4654 glows nice, for example:

On older ones, which have darker coating, and on a bigger surface of the glass, and the heater does not reach so high as on this one it's not so spectacular. But I have to admit that I tried those only on the tester.

The RCA 9002 is also looking nice for such a small tube:

This one will be appreciated by the Tube Inquisition, triple mica and so on. Everyone thinks it sounds better. In my case when I see this I remember 5691 and 5692 which are some of my worst tubes from my collection. I appreciated them only when I wanted to mask something. It was perfect, they masked harshness, detail, everything. LOL

 

[triod750]

With some tubes masking is a blessing. Then you go on and find better tubes...

 

[Isaacc7]

I am on a vacation visiting my parents. Predictably, I miss my system. Going cold turkey has apparently been too much for me because I have fallen off the wagon and ordered some more tubes and adapters. Sigh.

I finally ordered the 2x triode 6v6 to 6sn7 adapter. I have been having so much fun with other pentodes in triode mode as drivers I want to try this out. I won't actually be using 6v6 in them directly. I will be using 6f6 and 6k6 in them. And by adding other adapters I will also be able to use 6aq5, kt81, and 7c5. I actually already have all of those tubes. Just what I need, 5 more driver tubes... If I get bored I guess I can also try el95 but that would mean breaking my no new tubes rule again lol.

I also finally broke down and ordered some n78 tubes. I have heard that these are essentially a slightly de-rated el84 made by GEC. They are cheap enough but of course I needed another adapter for them. The only other tube I think I can use with these adapters is the el91/6am5. Don't think I could use those as an output tube but I could put them in the first adapter I mentioned and use them as drivers.

 

[OctavianH]

Going cold turkey has apparently been too much for me because I have fallen off the wagon and ordered some more tubes and adapters. Sigh.

Ah, do not worry, it was predictable. Double 6V6 to 6J5 are useful, I also have single 6V6->6J5 and use them from time to time with pentodes on input, but only with something with at least 20 gain. Because of the 6V6/6J5 almost similar pinout except G2 I also plan to use in the 6V6 slots some adapters towards 6J5. Have to work, I think. I do not see a reason to have a problem with a "triode" or "triode strapped" tube to 6J5 put in the 6V6 slot.

I stopped buying tubes, I have all I need and also a few interesting types I will try soon. I'll make a preview for you:

But not only these ones. I found a gold mine analysing loctal sockets. EBL/ECL families or even EF are very interesting. More about this later.

If I'll tell what I am doing now I'll summon the Cable Inquisition. Since source is the weakest part in my chain, using the PC via JCAT USB XE and a 3m USB cable to M Scaler, I have decided to investigate possible improvements. So at the moment I increased a lot the bass and changed the whole presentation of the headphone line by exchanging the Kimber Kable USB-Ag with QED Reference USB. And the difference is not marginal. Of course this one comes with less extension on the highs but sounds an idea less dry on the midrange. I plan to check how will sound this one with EL50. Maybe I will fix some downsides of some tubes I love by tuning a little bit the rest of the chain. I have not done this in the last 4 years.

I also tried a trial of HQ Player, software upscaler, to check if indeed M Scaler can be replaced. After a few hours of different filters and settings and so on, my resolution is that M Scaler is better, sounds more natural and organic. But HQ Player in a line with copper cables might be closer. I have here silver interconnects and changed only the USB cable and HQ Player sounds an idea less sterile. But still cannot touch M Scaler. I'll keep it here for 30 days but at the moment I do not plan to buy a license. I will spend some time to investigate how I can improve my source, then return to tubes and our normal activities. Anyway it's incredible what is happening on other threads, it's a war out there. Cable inquisition explains how an Aliexpress cable is the same as a much more expensive one, headphone inquisition makes graphs to determine why a headphone is wrong. There is also the Topping inquisition, explaining why Topping are the best DACs in the world. I had to run in trenches and I will never return there. I will make my own experiments and hide. This is the problem of this hobby, everyone has an opinion, most probably wrong. And we know the gauss curve of IQ. LOL

 

[Isaacc7]

The 5b/254m tubes are great. Some of my favorite drivers are triode strapped pentodes. The ktz41, c3m, and 5a/152m keep rotating through my amp. The Fivre 12j7 also get used from time to time. Just got in a bunch of Russian 6j7 and will try them out soon.

There are multiple threads over on DIYaudio that use 6v6/6aq5 as preamp tubes to great effect. The 6f6 data sheets specifically mention using them as triodes as a driver tube. I'm looking forward to trying them out along with the kt81. If the kt81 sounds good I might be "forced" to get an adapter to use the n34 and n43 tubes as drivers as well.

It never ends does it?

 

[Whazzzup]

tube wise we 5842 driver ta 274b rectifier and kr 2a3 power tubes and wow bloomed real good. concerning this hobby, its all cognitive dissonance, intra company cults, and marketing one up man ship. if because i followed and didn't follow the mantra of fan boys to engineers saying do this don't do that, put another box here an is2 there a power conditioner there and a master switch there, a b/c cable etc...use each company as you wish, use your ears if one can, and the hype may be hype until you like what you like. I could have made many wrong turns paying too much attention

 

[OctavianH]

The 5b/254m tubes are great. Some of my favorite drivers are triode strapped pentodes.

They look cool but I've observed on mine that the date code was applied later and has another size. For example:

All are KB/F but codes are KE, missing, MJ or LH. Three have black plates and one is grey.
F=STC, Paignton
KE= May '54
MJ=September '56
LH= August '55.
I hope I remember right that it's YM according to that GEC table. Grey plate seems an idea older than the rest.

I've just observed that the one without date code has dual ring getters on top, the rest have a kind of double rectangles.

It never ends does it?

Well, it never ends but might decrease in intesity once you've got what you need. However, from time to time you'll see something nice and try. This is my case.

 

[Isaacc7]

They look cool but I've observed on mine that the date code was applied later and has another size. For example:



All are KB/F but codes are KE, missing, MJ or LH. Three have black plates and one is grey.
F=STC, Paignton
KE= May '54
MJ=September '56
LH= August '55.
I hope I remember right that it's YM according to that GEC table. Grey plate seems an idea older than the rest.

Well, it never ends but might decrease in intesity once you've got what you need. However, from time to time you'll see something nice and try. This is my case.

I'm sure they'll sound good regardless of if they match or not. They're bound to be more alike than different I'd think.

 

[triod750]

I have received a recommendation; keep it simple stupid, just shut up and listen!

 

[Isaacc7]

I have received a recommendation; keep it simple stupid, just shut up and listen!

Was meant to be reassuring! Lol

 

[triod750]

Before I ever heard it I had told myself the same thing to no avail.

 

[OctavianH]

I had some unpleasant surprises lately, this time related to D8000 Pro. After returning the HEDDphone TWO and receiving the full refund (by the way, HEDD are a top class company and maybe my best experience until now in terms of communication and support, they paid even for the shipping back to them which normally was my duty and refunded me in 2 days time) I decided to remain on the D8000 Pro which is the most "complete" headphone I ever had the chance to listen.

But life does not listen to your plans all the way. Two days ago my left earcup of D8000 Pro stopped functioning. I said it is "the driver" but it was the 3.5mm mother jack inside that metal body which is not very easy to reach since, well, you need to disassemble the complete earcup to be able to touch it. Not fun.

The jack is somewhere after that stupid "locking" mechanism so you do not realy have a chance of reaching it. The metal body is made from one piece. In my case the locking mechanism is not used at all because I use a custom cable which is, for me, much better than the stock one. The problem is not permanent if you keep the cable into a specific position but in time it will be come permanent, so it demands fixing and my first try would be Final, in Japan, and later to do it by myself and take some risks. Of course if they will service it out of normal warranty time and the costs will not exceed what I consider decent.

Regarding usage and how this problem has appeared, I listen to it around 12 hours / day but removing cables was done only around 40-50 times. In my view, it should not be a problem for a headphone jack with this price point. If that is a problem, what to think about the teflon sockets of my tube amplifier? But well, even one of the best built headphones in the world might develop a problem.

In the meantime, since the process will take a while, I decided to make another try in adding a back-up headphone to my collection. So here we are, in the point where I bought a pair of Hifiman HE1000se. Not because it is better, more because it was cheaper, different and I had 36 months warranty at a local dealer if I'll ever decide to keep it. I use headphones heavily so you know, 3 years for me are more than average usage.

I also "fixed" the D8000 Pro temporarily but of course, not a solution. So after I see what the manufacturers tells me I'll have to obtain a final solution. But in the meantime I have some time to play with the wonder of "chi-fi" world called HE1000se.

I put directly the Forza AudioWorks Noir Hybrid cable to be sure that I am not loosing time with other cables. On every headphone I liked this was, after several tries, my last choice so I think it would be ok also for this one. If not, I have a few another options here since both D8000 Pro and HE1000se have the same 3.5mm connectors. So cables are not a problem for me.

Being a very different headphone in terms of signature, I do not want to form an opinion before a few days of usage, but I will say one thing: gone are the days of natural and organic sound with lifelike bass reproduction. This one sounds metallic for me compared to D8000 Pro and build quality is also much below, but this was not a surprise for me.

This change of headphones will affect my activities because I doubt this one reacts so good to tube rolling like the D8000 Pro. Neither of my previous headphones was so good in showing you nuances of different tubes, so in my view this one will not match that unique quality of D8000 Pro as being a "chameleon". But it's resolving, fast and decently comfy.

PS. Another strange result I had these days is related to the Tung-Sol 6SL7 I had problems on Eternity a few weeks back. On tube tester works fine and measures the same. So, I cannot understand what happened. I'll investigate more.