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Analog Squared Paper Discussion Thread. - Page 14

post #196 of 3713
An Addendum!
I just had a lovely email from Steve at Mullard Magic, He goes on to explain more about these and says that the highest possibility is that they are RFT manufactured valves from East Germany and certainly not Marconi though what he means by that is I think a bit like generic medication vs brand name, Tylenol is the brand name for Paracetamol or acetaminophen So Marconi is Tylenol as RFT is to Paracetamol.. At least I think that is how it works.

So I did some research on RFT and it seems they are excellent quality valves and often Siemens or Telefunkens are re-badged RFT's I am sending some pictures to Steve of my Siemens tubes as he feels they may be RFT's as well. More to follow..
post #197 of 3713
And one more update!
Steve very kindly checked on the Siemens DF91's as he thought they might be RFT as well, turns out they are in fact made by Siemens themselves!
What a great resource Steve is.. He sells valves as well you know and someone who gives so freely of his time deserves support and business!
post #198 of 3713
Ahh, some sublime music tonight curtesy of Hi Definition Tape Transfers..

Sibelius's Violin Concerto in D played by Ruggiero Ricci and the famous Sir Thomas Beecham, RPO version of Pelléas et Mélisande. (more famous if your British and loved the late Sir Patrick Moore!)

All taken from historic tapes and in 24/96, what an evening ahead with my wonderful amp and this beautiful music!
post #199 of 3713
Telefunkens have arrived and are as I type burning in. Initial thoughts are smooth yet revealing. Great ability to reveal texture. Both are early D getters one has a shiny plate the other matt finish otherwise identical. The writing is a little faded but all the codes are there so I will do some research.

Currently I am running all German tubes, Tele's in the power section, Lorenz's in the voltage gain stage. Some proper listening tonight!

Come on folks with this amp, join in the conversation on what you think of your amp.
post #200 of 3713
Initial thoughts are with almost 2 1/2 hours on the tubes, so bear that in mind as in the past there have been changes with more hours.

The Telefunken's are a much drier sound than the Marconi's but they have no more detail retrieval and listening back to back texture is the same as well. Bass is a lot less than the Marconi's adding to that dryness of sound.

Now, I am not a bass head but I do like realistic portrayal of bass and the Marconi's beat the Telefunken's in to a cocked hat in that respect.

With all the tube rolling I have done these past few months I felt commenting now would be appropriate as what the Tele's are lacking in with the little experience I have will not change with burn in, I think they are a dry tube.

Now, if one had an overly rich amplifier then these would be great tubes for that but the TU-05 is pretty much neutral as far as I can tell, just gets out of the way of the music so tube's make an even greater importance with this amp insofar as tailoring the sound to ones desired type.

I used the time honoured Hell Freezes over Hotel California track as the test today. I know that album backwards and forwards! When the drum beat kicks in it goes deep and it is rich and textured, then the second layer of percussion comes in and with a good set up the bass is deep and yet detailed and both drums can be told apart and the tonal variances easily heard.

With the Telefunken's that really just was not there. It did not go deep, it was not rich and though there was texture it simply was no where near what the Marconi's or to a slightly lesser extent the Mullards bring to the table.

The initial feeling of detail retrieval over the Marconi's is a bluff really, because there is little richness the details stand out more with the Telefunken's but they have no more than the Marconi's or Mullards. The Mullards and Marconi's bring life to the table, they bring a humanity that the Telefunken's could only dream of!

When I ordered the Marconi's and Telefunken's I must admit the Marconi's were just because they looked so damned pretty and in truth I thought they would end up as decorations while the Telefunken's of which I have heard so many good stories would be my go to power tube.

What ever origin the Marconi's are I do not give a jot! I don't care that they were made elsewhere for the Marconi group and labeled Marconi that they just stuck on that pretty shield for it is the sound that matters and I just wish I knew definitively who made the ruddy things so the rest of you could enjoy the sound they make!

I have switched back to the Lorenz's, though there are things about the Siemens I love and they are wonderful tubes it is the Lorenz's that pull the heart strings ever so slightly more as is the case with the Marconi's

But fret not, if those two have the property of unobtanium then there is an answer that will bring you to within a hairs breadth of these to sets of tubes.

Early Mullards in the power section and early Siemens in the voltage gain section. Think of those two as the cake with icing and the Marconi's and Lorenz's as having just the sprinkles on top!

I really , really do not recommend the Telefunken's with this amp, they are simply too dry! In fact, any of the other tubes I have used in this rolling spree would be my choice over them!

Positives about them? Deadly quiet, zero Microphonics.

The Marconi's are absolutely silent as well except for some slight ting tings but that is only if one taps the amp, to all intents and purpose they along with the lorenz's leave an inky black background for which to enjoy the silent passages in music.
post #201 of 3713


Edited by seeteeyou - 11/4/14 at 11:30pm
post #202 of 3713
Oh, this is way beyond my knowledge base, I look forward to someone else who can help here so that I can learn. If it makes a difference there are two types of caps one can have with the TU-05, standard and upgrade. I went for the upgrade which are black and gold Nichicons.
post #203 of 3713
Just been talking with Shikada San about other tubes that may work with the amp. He gave the go ahead for me to try DF96's in place of the DF91's and report back to him. He thinks the only possible issue is that they may not produce enough power. I will get a cheap pair at first and report back. If they work well it gives us a bit more choice!
post #204 of 3713
Just been back to back with the Marconi's and other tubes to see if there are others apart from the mullards that come close to this rare tube so that others can experience a bit of what I am experiencing.

I would say the French (owned by Phillips) La Radiotechniques come a touch closer than the Mullards in comparison to the Marconi's as they have a little more air. The only thing they lose out to the Marconi's is a bit less depth in bass but it is small, really small.

The 3S4 La Radiotechniques are much easier to find as well!
post #205 of 3713
Just ordered some NOS Mil spec Radiotechnique 1T4's made in 1962, should be here next week!
post #206 of 3713
The Radiotechniques have arrived, The seller, DBtubes in Quebec is excellent to deal with. The pair are my first matched pair of tubes so it will be interesting to hear if that makes any difference. Also. I have been running the 3S4 equivalents for the past week and loving the sweet sound these French tubes produce.

For only the second time since getting this amp I will have the same make in both the 3S4 stage and the 1T4 stage, last time was the Mullards. Right, Off to prepare the pins and get some burning in started!

Oh, one last thing. What is really cool is as these were made for the military the boxes contain a great deal of information including the date of manufacture which for both (they are from the same batch run as well as matched) was the 24th September 1962, just over a year before I was born!

PS. A tweek! As some may know I made a wooden cradle for the amp so that it does not topple over. I lined this with sheet cork and it has been a great way of not only securing the amp but also contributes to sound quality.

Of late I have been researching about isolation and damping for audio products and read about brass cones and such. Instead of damping what one does is allow the energy produced by parts such as transformers to dissipate via metal cones.

So, being the cheapskate that I am I thought before spending money on cones I would find a DIY solution! What I have come up with and works fantastically are the brass compression rings one uses to join metal pipes together. I have found for best results two at the back and one in the front in the middle work best. I guess as one of the transformers is at the front and on the bottom it makes sense.

What this has brought sonically is a greater depth to the sound stage. More detail and yet an even greater ease in musicality.. All for $3!
Edited by ianmedium - 5/7/13 at 2:54pm
post #207 of 3713

Have any pix of the NOS Milspc RadioTechnique 1T4's and the cradle box for your amp? You've raised a good point about the amp toppling over actually - something I've wondered myself.

post #208 of 3713
Absolutley! Just took a few quick snaps. I cobbled my stand together out of off cuts and then sprayed it red. Rank Amateur is the best way to describe it but it works!. You can just see the brass compression ring underneath which dissipates energy.


This one is of the tubes. The ones with green printing are the 3S4 Radiotechniques, those ones were NOS/NIB domestic market ones. The ones with the white bulb with "RT" in the middle are the Mil-spec ones.

And these are the boxes, same lot number and David at DB tubes matched them as well though strictly speaking it is not needed with a single ended triode operation.

I have been burned before when I have commented right out of the box but on initial listening this pairing and brand has it all.. More later though!
post #209 of 3713
One of the things I love about these NOS tubes is doing research on the history of them. Sometimes nothing comes from it, other times a lot.

I have started to research the markings on the Radiotechniques and it is hard as the only documents are in French and it is testing my school boy French as I cannot google translate them due to the flies being to big. So far though I have found out that the "STTA" marking refers to the Technical service Telecommunications Air which from what I can gather is the department responsible for communications in the French Airforce but I stand to be corrected on that!

Still cannot find out what the "AIR" in a circle is. I am guessing it is a marking for perhaps tubes used by the airforce, will do some more research to find out.

I am dying to tell you how they sound but must bite my lip until I have a few more hours on them but I will give one clue! The will be very enjoyable hours wink.gif
post #210 of 3713

Thx for the pix. Great job on the stand.


I'm a noob when it comes to tubes (just owned my 1st tube amp a week ago - Zana Deux). I noticed you changed only 2 of the 4 with the 3S4s?

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