floobydust wrote:

I do agree that the internal structure makes a big difference... but, if the tube specs properly and has adequate immunity to mechanical induced interference, then you should not be able to discern any major difference in sound quality, at least not in well made NOS tubes as the industry had the same technology, materials and processes.

floobydust wrote:

Finally, here's the Sylvania 2A3 with the coil spring supports

Very good, floobydust. They are exactly my thoughts about the “period tubes” as well. In addition to that I think that factor that call “Holly Ignorance” did take place with some vintage tubes. They might not have too high demands for the quality of the tubes 60 years back but they have not yet developed bad technological habits back them. It is very similar to making speakers drivers – in past they did not have high demands to quality but they did not have back then the nowadays idiotic ideas how sound might be taken out of loudspeaker by barbaric methods.

Saying that I have to note that that idea of contemporary production by sensible and knowledgeable people of some vintage tubes do look attractive and the Chechslovakians are a good illustration. The concern that I have is that they might replicate and I am sure improve the contraction. However, I do not think that the today tubes makers might do anything with materials. It is highly possible that all materials sources by all manufactures from the same “generic” suppliers – considering the quality of today tubes production no one would cook metals and coatings specifically for tubes. Well, how different would it be from many other fields?

floobydust wrote:

I don't really know anything about the YO185 but would like to see some info if available.

http://www.romythecat.com/GetPost.aspx?PostID=9344

http://www.romythecat.com/GetPost.aspx?PostID=9407

floobydust wrote:

The 10Y was obsolete long ago and the preferred replacement was the 801. While they are similar they are not identical. There are two significant factors that differentiate these from the 45/2A3 variants: 1- They use a thoriated filament/cathode which requires 7.5V. 2- They require a fairly high load impedance (around 7K) and higher plate voltage (around 600V). The down side is also two-fold, higher impedance OPTs are more difficult to make and keep an extended high-frequency response. The filament/cathode design will require a DC supply to keep the hum out. You won't gain any additional output power over the 2A3... about 4-watts max. It will cost more to implement and it's doubtful if you'll get any (audible) improvement over a 2A3.

Hm…  I do not know. I have some sources that I respect who in fact very much encouraged me to go for those thoriated tungsten cathode tubes with very high impedance in plate just because strictly considerations. I less care about the high-frequency response as in my care it will be DSET for 1kHz and up (3200Hz electrically) and therefore the transformer shell not care any inductance. If I go for LF cut off let say 400Hz then it will be possible to use reasonably-minimum amount of widening and HF would not be a big deal. The only thing that holds me is that many of 10Y/VT-25 out there are dead or “wrong version”. I did explore the subject. With 2A3/45 it is more attractive as there are so much more options…….

floobydust wrote:

Finally, I'm not sure where your preceived need of four transformers comes from. I have 45 and 2A3 designs which are flat out to 45KHz at full power with low distortion and the only transformer in the signal path is the OPT.

When I said four transformers I meant that I can see 4 type of the tubes. The 2A3 with 700-80R on plate, YO186 with 1200R on plate, the 45 with 1800R on plate and 10Y with 5K on plate. Hey are requires different transformers.  I do not like taps. I like to have transformer with remapable sections. The 2A3, 45 and YO186 still might be possible to care with one transformer; the 10Y would need a very different beast. Also, I have a filing this time to try something different. I might go with DHT for a slower core OPT but to load anodes more idle – I have a feeling that it might bring me where I would like to be. I am thinking about 4.5K-5K for 2A3 – I mean a lot of impedance, as much as my S2 will be able to handle. I even will to give up a bit speed of my code for trying it…. In my single-stage IDHT amp I have no gain to afore this luxury.

floobydust wrote:

What is/was your thoughts on circuitry?

I invasion absolutely nothing fancy. It might be the very same Milq’s driver stage:

http://www.romythecat.com/PDF/Melquiades_SET.pdf

with only differences that as the output tube will be cathode-based DHT. I still debate if to couple it with good quality cap of transformer of 1H inductance. Bothe ways have attractive sides. Anyhow, I begin to sound like Lynn Olson with his inexhaustible BS-talk about his bogus loudspeaker project…

floobydust wrote:

Okay, I think I understand.... and thanks for the link on the YO-186... if I can ever locate some of these I'll be sure to grab some (hmmm, a trip to Russia perhaps). As tubes get very hot internally, there were some procedures for trying to eliminate the possibility of "out gasing" from the tube elements, if they were exposed to internal heat levels beyond their ratings. Transmitting tubes were a good example as many of these had cherry red to orange anodes for CCS operation. Even the high powered VR pass tubes (6336 and 6528) had anode materials and processes to ensure "out gasing" would not be a problem when deployed in high-current applications. It's not very clear how much of this exists today with some of the new manufactured tubes.

This is one of many subjects that so much attracted by in YO186. It reported that tungsten cathodes have no such a problem (or less) but the oxide cathodes with their higher efficiency have a tendency to gas the tube. When the electrons are boiling on the cathodes it reportedly some kind of gas get created that in a long run screw the tube and the can’t be properly be absorbed by other gas-handling methods. To minimize this effect the pre-fabricated cathodes before they placed into the tubes exposed to overburning. The over burning  reportedly is some kind of sophisticated  ceremony where cathode is heated to very high temperature, much-much higher then it even will see in regular life and then submerges in some kind of cold chemical broth.  It is reportedly a sophisticated and expensive ceremony that was done in past and allegedly discarded by today makers of the tubes. So, according to my Russian sources the YO-186 was exposed for overburning three times (!!!) before the cathode was accepted for this tube. I do not want to create a myth about it but if it was true them it very much goes along with the vision that in past people did not try to save on the things that that are important.  I do not know if all of it true but allegedly the YO186 was one of the very few tubes that was exposed to triple overburning.  Perhaps the facts like this explains why some of the older tubes run for 50 years and still “measured as new” (even I personally do not support this notion)

Floobydust,

I have a question to ask. Those dam Ruskies when they did the YO186 then made it to have an absolutely idiotic pin layout. The layout is very simile to 2A3 but one of the pins a few mm away, far enough for me to consider that it would  not be save to bend the pins. So, what I heard is that in 30-40 Germans made the similar pins and I wonder if any tubes sockets for them are available? I told that there is a Germany aftermarket company that make those add sockets very recently. So, since you are in Germany, or any other Germans – did anybody see the “faulty” not-fitting 2A3 tube sockets? It is not imposable to accommodate some other solution to YO186 but I would prefer to buy off the shelf socket and do not be bothered with it.

The basically the same tubes. The 6E5P has own unit pins layout with heaters connected across the tube – very moronic in my view and it does not allow twisting the AC filament wires to the very end. The 6E6P has a common pins layout that most of western tubes of the same type use (D3a/7721and etc). The 6E5P is a bit larger and can dissipate heat better when you drive anode closer to 7W-8W.  They have different data in datasheet but it only because the 6E6P has more strict parameters and therefore on paper it provisioned for lower voltage, voltage power and shorter life. In reality is just because 6E6P the residual requirements for 6E6P were higher. The 6E5P considered consumer tube but 6E6P had a military version – the 6E6P-DR. Those tubes had ever more stringent requirements and the data on them was QA after the tube was burned out. Some of them had gold pit and so on. BTW, if you buy the DR tube then you will see that they even new look like they were used with darken glass – this is the result of pre-burring on factory.

Both the 6E6P and 6E5P need to be use in the same way – 200V on plate and no less then 15K on anode. Do not forget the grid sopped – they are very fast tubes.  Stonily they are very similar in my view with a very slight advantage of 6E6P in delicacy and softness. But it is VERY minor, near negligible. Among all 6E6P and 6E5P that I had I have seen only one that was microphonic.  Be advised that those tubes tine pick up some HF nose as they age and become worn. Also be advised that both 6E6P and 6E5P are noise what they cold. As the heat up they shall become calm and silent, usually it takes 5 minutes. I do not know what you mean “respond differently regarding vibration” are you heating them with baseball bat and mount them on a top of  the Vibratex Rabbit Habit Vibrator?

Romy the Cat wrote:

Stonily they are very similar in my view with a very slight advantage of 6E6P in delicacy and softness. I do not know what you mean “respond differently regarding vibration.”

Romy the Cat wrote:

Floobydust, I have a question to ask. Those dam Ruskies when they did the YO186 then made it to have an absolutely idiotic pin layout. The layout is very simile to 2A3 but one of the pins a few mm away, far enough for me to consider that it would  not be save to bend the pins. So, what I heard is that in 30-40 Germans made the similar pins and I wonder if any tubes sockets for them are available? I told that there is a Germany aftermarket company that make those add sockets very recently. So, since you are in Germany, or any other Germans – did anybody see the “faulty” not-fitting 2A3 tube sockets? It is not imposable to accommodate some other solution to YO186 but I would prefer to buy off the shelf socket and do not be bothered with it. Ich bin Katze

drdna wrote:

As I had been looking at all these tubes I began to also inspect their interior construction. This will amuse you: one thing I would do is to hold the tube right up to my ear so the glass would be touching and thus mostly damped. Then tapping the tube slightly would cause the internal cathode and anode to vibrate a bit, making a noise. There was a correlation between the type of noise and the sound the tubes in the stereo would make when music was played.

Years back what I used Lamm LP2 phonostage with notoriously microphonic 417A tubes I was doing something similar by maxing out volume, sticking the head into the horn and hitting the tubes with a little hammer with rubber coating. I was under impression that the character of noise and the decay of the nose would symbolize how good the tube was. Well, it did and did not. It helps to filter out the obviously bad tube but if does not helped to predicts how it might sound. Pay attention BTW that my methods was using hot tubes, not the cold tubes. If you feel that you are able to get the correlation between the type of noise and the sound then it is fine but I feel that it is more contrived self-convincing. I do clear remember the I had some tubes that did not have the lower noise (they were passable though) but they sounded the best. I think this method is OK to filter out the tubes of the same make (brand, type, vintage) but I think it is worthies if you try to compare the resonating noise of the tubes that have even slight construction differences.

drdna wrote:

I don't have a circuit built now for the 6E5P, but I have a bunch of 6E5P & 6E6P tubes. Based on my examining them I was guessing that the 6E6P should have slightly more "clean & neutral" sound than the 6E5P. I was curious if this was the case, so I thought to ask you, since you have a familiarity with both tubes.

You can make what I did. I made a small adapter that cross wires and convert 6E5P into 6E6P. Then you can plug in your tube socket whatever tube you wish. BTW, the 6E5P and 6E6P have in a way a unique construction that has a lot of to do with the way how Russians shaped in this tube the profile of electron cloud. The 6E5P and 6E6P were reportedly made to completely eliminate the Dynatron effect. I do not know or they did or not but the spaces in there are atypically huge, it is a fact. I have no idea how all this affect sound but I like how it sounds. Plug it in and you will hear it yourself.

Romy the Cat wrote:

drdna wrote: As I had been looking at all these tubes I began to also inspect their interior construction. This will amuse you: one thing I would do is to hold the tube right up to my ear so the glass would be touching and thus mostly damped. Then tapping the tube slightly would cause the internal cathode and anode to vibrate a bit, making a noise. There was a correlation between the type of noise and the sound the tubes in the stereo would make when music was played. If you feel that you are able to get the correlation between the type of noise and the sound then it is fine but I feel that it is more contrived self-convincing.

Romy the Cat wrote:

When I said four transformers I meant that I can see 4 type of the tubes. The 2A3 with 700-80R on plate, YO186 with 1200R on plate, the 45 with 1800R on plate and 10Y with 5K on plate. Hey are requires different transformers.  I do not like taps. I like to have transformer with remapable sections. The 2A3, 45 and YO186 still might be possible to care with one transformer; the 10Y would need a very different beast. Also, I have a filing this time to try something different. I might go with DHT for a slower core OPT but to load anodes more idle – I have a feeling that it might bring me where I would like to be. I am thinking about 4.5K-5K for 2A3 – I mean a lot of impedance, as much as my S2 will be able to handle. I even will to give up a bit speed of my code for trying it…. In my single-stage IDHT amp I have no gain to afore this luxury.

Studying YO186 I concluded that that it was not AD1-type tube as it was mistakably considered but it rather was an equivalent for RE604, LK460 , E406 , KL71403, K435/10, P460, P4, O15/400, RE614, U4H

They all 4V with near 1A on filament. They all from one to two kohm on plates (with exception of U4H that has 4K), basically 1.3-1.4K in average. The YO186 with it 1.2K would feet the bit but the plate impedance would greatly vary with operational current anyhow.  They all have gain of 2-3-4. And the YO186 is right there. The all have 30-40 on grid and semi-identical size with YO186 with YO186 being a bit larger. The all 10-12W on plate with YO186 15W but I think here is where the YO186’s larger balloon is in advantage. So, I think the YO186 with RE604/KL71403 have found its family.

Looking at the externals construction of Telefunken RE604 and Klangfilm KL71403 I kind of surpassed that YO186 is made better or I would say more refined. It would serially say nothing about sound or about the quality of materials were used. I was not able to found anybody who used RE604 and YO186 or KL71403 and YO186, so I have no idea how one stand against other. As one guys said to me: “Romy do not search anyone - you are the person to answer this question.” Perhaps I am, as there are very few YO186 users out there. I would be very interested to see how the RE604/KL71403/YO186 class tube would push against the 2A3/45/6A3 class and the 300B class.  Of course there is a great variety of differences between the different between of the same DHT tube, but still it is interesting to know if any common tendencies are there. it is very much might be that there is no important differences in any of it and it will all depends from how good the given tube was made. I plan in future to buy one RE604 and one KL71403 to see were the YO186 stands (as I have life supply of YO186) but first I need to found out the answer for the main question: how much S2 driver in context of Macondo will b e able to endure the YO186’s loading.

People out there usually load RE604/KL71403 to 3.5-4K getting from RE604/KL71403 1.5-1.8W. That might be a good start for YO186 if I run it at 57mA but sine I will be running my YO186 with no bass then something suggests me that I might end up with lover currant, higher plate impedance and might load YO186 to 7-12K. The “sucks” part in all of it that it is difficult to found out what I need without actually falling in something and recognizing of with what I do not need…

Each new idea is an opportunity or a pain to be involved into a new round of custom work. With all my considerations regarding engaging the DHT I more and more biased to have YO186 as the leading candidate, in fact I almost decided to do it.  From a certain perspective the YO186 is Russian-made RE604 that is good itself, considering the mythical quality of sound from RE604 but there is a twist in it. If the YO186 was mane in 1947 then I would say “Yes”, Russians copy the RE604. BUT, first the YO186 looks like none of the Telefunken or Klangfilm tube of the period and second the YO186 came to production in 1932 and this make the story VERY interesting.

The Russia of very beginning of 1930s is an interesting time. The generation old empire engineers among those who do not escape to west or was not killed still were around and it is very possible that Telefunken stolen RE604 from Russians, or at least that they were independent developments.  A commercial public radio was introduced in Germany in 1923 and in Russia in 1926. So, Russian in beginning of 1930s had people and recourses to do the interesting things and they did.  So, the YO186 might be an interesting tube on it’s own.

Anyhow, returning back to the pain of new round of custom works. It looks like I would need another low inductance output transformer 20:1 or even perhaps 5 more.  This sucker needs to be ordered but I kind of debating what I want this time. I have two options: to go for fasters core (amorphous) as I did before and load the tube a bit harder or to go for more mellow core (cobalt, nickel, Mu-Metal, chicken, wood etc) but to let the plate to idea a bit more. With 350V and 30mA I will get around 3W from YO186 – much more then I need, so I can but some power on damping, thankful the gain won’t be an issue with two stages anymore.  The question is how much S2 driver will be able to handle – I have no idea until I try…

Since I kind of targeted with my YoYo tube to the RE604-class then I am considering to pay once a lot of money and to buy one of those RE604 to see how much YO186 better or worse. (BTW, do not be under impression that YO186 is cheap – it is not still it is not $1500 per NOS RE604). Standing the park of small oxide power tubes from 30 it look like there is a great variety of the tubes that that I might be using in the amp above if I go for YO186.

Besides the mentioned Telefunken RE604 and Klangfilm/Siemens KL71403 it also might be Philips RE-614, Valvo LK460,  Triotron k435/10, Mazda 601 or DW302, Mullard AC084, Ferranti P4, Tungsram P460 or O15/400 ( the last has slightly higher plate impedance) and Marconi PX4.

The similarly of YO186 with PX4 opens a whole new chapter in exploration of YO186. I think I did heard an amp once with some kind of yellow driver but I did not paid attention to it’s sound.  During that times all of those DIY amps I considered as people soldered instead of sniffing bangs. I was too far from truth as the owner of the amps was “dead”, still it would listed that amp now just for sake if my curiosity in PX4.

Interesting that Prague-based company KR Electronics that Adrian pitched above makes today production of PX4

http://www.kraudio.cz/pic/px4.jpg

That kind if make my idea of going for RE604-YO186-class tubes kind of expendable and not so dead-end bookish if the YO186 heat the wall sonically. I was trying to found out how much KRs’ PX4 cost but it looks like no dealers have them. Are any visitors on my site from Czechoslovakia who can quote the KRs’ PX4 price? As anyone around Boston who run PX4 and would be interested in temp PX4/YO186 swapping for few days?

Romy the Cat wrote:

Those dam Ruskies when they did the YO186 then made it to have an absolutely idiotic pin layout. The layout is very simile to 2A3 but one of the pins a few mm away, far enough for me to consider that it would  not be save to bend the pins. So, what I heard is that in 30-40 Germans made the similar pins and I wonder if any tubes sockets for them are available? I told that there is a Germany aftermarket company that make those add sockets very recently. So, since you are in Germany, or any other Germans – did anybody see the “faulty” not-fitting 2A3 tube sockets? It is not imposable to accommodate some other solution to YO186 but I would prefer to buy off the shelf socket and do not be bothered with it.

I never used any of them but it is not a big deal to found them, even Chinese nowadays make a tone of them, the “gold” plated.