[GermanGuy]

after having modified my amp something remarkable happened. i started to listen to the amp with the RFT DF97 - Philips DL92 combo and really was blown away because of the unbelievable precision, detail and micro detail, texture and a clearly increased soundstage width and especially depth.
 
at first i thought it must have been a result of the modification itself using the dl92 in power safe mode so resulting in a better separation between the df91 and the dl92 stage heating power lines.
 
after having spent two days of listening the amazing result was, that the RFT DF97 was responsible for this changes:
 

 
 
The RFT DF97 has an amazing level of detail and fine detail and a soundstage width and especially depth to dream of.
 
i then tried different dl92 or compatible tubes with the following results:
 
The RFT DF97 - Philips DL92 combo is the absolute dream set when it comes to soundstage, detail, bass and bass texture. i never heard something like that.
 
this combo has a level of resolving the music that is unbelievable. each single instrument, voice, string has its own dimension, soundstage ,attack, decay, space around up to a level you could measure the size and distance. the only problem of this combo and this is the only problem of the RFT DF97 that at high level the sound and the highs can get slightly harsh, but layering, imaging, bass, bass depth and texture are exceptional.
 
This combo is wonderfull for voices, strings, classical music, but also listening to pink floyd, the wall (i never heard this recording so 3D like and real) is pure fun. the presentation is so full of details that it really forces you a little bit to listen to, activ listening is needed, not relaxed sounding due to the attention needed, but in any other aspect a real step up on the ladder of sound quality.
 
i tested my usual dl92 standard tubes and while bass texture is best of best with the Philils DL92 one could classify the tubes as follows in combination with the RFT DF97:
 
Philips DL92 - great bass texture, slightly warmer sounding than the others, but not warm like the Mullard-Phillips Combo
 
Tung-Sol mil-spec DL92 - Just in the middle, neutral to slightly bright, slightly less soundstage especially width, exceptional detail and high resolving
 
Tesla 1L33 - more on the bright side of sound, moving all the properties more to the midrange and highs - higly analytical - depending on the music slightly harsh at high volume, less bass and bass texture
 
a very fine and detailed sounding combo is also the RFT DF97 - Siemens DL92 combo.
 
i testes also some 1s4 tubes with rather average results, but today i got two PHILCO 1S4:
 

 
The RFT DF97 - PHILCO 1S4 combo is a real dream set, because it has all the properties of the Mullard DF91 - Philips DL92 combo (slightly less bass texture) but is a warm sounding combo and at the same time the first warm, beautiful and relaxing sounding combo with nevertheless no missing detail, fine detail, bite, attack and sparkle / highs and this great soundstage width and especially depth.
 
to be on the safe side i bought in total now eight RFT DF97 and one additional PHILCO, now having three of them with this special cardbox with the old fashioned font used.
 
can't wait to listen to the RFT DF97 - Mullard DL92 combo!

 

[GermanGuy]

Quote:

I was wondering about the general consensus among users?
 
Do you guys have the headphones/IEMs plugged in on powering up, or plugged in after powering? And on powering off, do you unplug the Headphones/IEMs first?
 
Many thanks................

before plugging in or unplugging the headphone i just turn the volume to zero / minimum.
 
if you switch the amp off before unplugging a heaphone and then again switch the amp on there is firstly the risk to generate a burst signal on the headphone out, and secondly the decrease of lifetime of electronic parts, especially tubes and integrated circuits is correlated with the number of power on / power off cycles.
 
and as the amp has output transformers between tubes and headphone, the voltage without signal must be (and is) 0 volt , it's just physics, a tranformer can only transform ac signals into ac output voltage, not dc or nothing.
 
but normally when i stop listening i just switch the amp off, and on when i want to listen to music, no need to always unplug the headphone first, my standard headphone or the headphone i want to listen to is always plugged in until i have decided to listen to another one (i have i think sixteen or seventeen, something like that, different headphones and iem's).

 

[woodcans]

Dedicated to Ian and his green and orange Tu-05:
 
 

 

[ianmedium]

Oh Man, that is wonderful, cheers WC!

GG, that sounds like one heck of a combination of tubes!

 

[GermanGuy]

Just received 7 x Orion 3S4T - after 2 months of searching for this type of tube.
 
i hope they sound exceptional, because the 3S4T needs only half the power of a dl92 / 3S4 standard tube, and using the 3S4T in powersave mode it needs only one quarter of the power normally needed for the heater:
 
Standard Tube Set:
 
2x DF91 + 2x DL92 = 2 x 50 mA + 2 x 100 mA = 300 mA for tube heating
 
"Lowest Power Needed" - Tube Set:
2x DF96 + 2x 3S4T (in powersave mode) = 2 x 25 mA + 2 x 25 mA = 100 mA for tube heating
 
This means you need just one third of the power for heating compared to a standard TU-05 with the standard tubes and without the powersave mod (or pin 1 of the 3s4(t) cutted) !!!!!!

 

[ianmedium]

I am really looking forward to hearing your thoughts on these ones!

Just a question for those who purchased the "stamp" Brimars, how quickly did they get to you? He shipped mine on Monday so hopefully they will be here around the same time as the amp!

 

[bmichels]

Quote:

after having modified my amp something remarkable happened. i started to listen to the amp with the RFT DF97 - Philips DL92 combo and really was blown away because of the unbelievable precision, detail and micro detail, texture and a clearly increased soundstage width and especially depth.
 
at first i thought it must have been a result of the modification itself using the dl92 in power safe mode so resulting in a better separation between the df91 and the dl92 stage heating power lines.
 
after having spent two days of listening the amazing result was, that the RFT DF97 was responsible for this changes:
 

 
 
The RFT DF97 has an amazing level of detail and fine detail and a soundstage width and especially depth to dream of.
 
i then tried different dl92 or compatible tubes with the following results:
 
The RFT DF97 - Philips DL92 combo is the absolute dream set when it comes to soundstage, detail, bass and bass texture. i never heard something like that....
 
The RFT DF97 - PHILCO 1S4 combo is a real dream set, ....
 
can't wait to listen to the RFT DF97 - Mullard DL92 combo!

 
Very interesting for me because, for some reasons, every Combo that I prefer always includes some Philips DL92 !  I Don't know why ?
 
Telefunken DF904 / Philips DL92, being my prefered combo so far ...except that I find the Telefunken very sensible to "titling" !   does someone experience the same ? 
 
So, RFT DF97 - Philips DL92 combo might be "my" dream set ? 
 
 
--> GemanGuy, tell me : are the Lorenz df96 <-> Tung-sol ken rad dl92 combo  and  Mullards DF91/1T4 <-> Tung-sol ken rad dl92 combo still your "best sets", or... have they be replaced by the valvo df91 red label - tung-sol mil-spec dl92 combo  or .... more recently by this new RFT DF97 - Philips DL92 combo  or.... the even more recent  RFT DF97 - PHILCO 1S4 ?  

 
You really have a lot of "dream sets".... ! 

  or, during your research, does each new "dream set" replace the old "dream set"  ?  could you classify those "dream set" for me ... I get lost ! 

 
 
--> which one would you keept if you could only keept one ? 
 
 
 
 

 

[ianmedium]

For me too the Phillips DL92 is my go to DL92, it has the depth and weight of the Mullards but with a little more detail and dynamics. I am finding my favorite combination so far in terms of sheer musical enjoyment is the Phillips/Mazda combo.

I too have found like GG I have favorites, I find it a moveable feast though as it depends on the mood I am in when listening. Sometimes I am in the mood for slightly darker tonal textures so the Mullards come to the for, sometimes light and airy and my German tubes enter the picture but for overall it has to be so far the Phillips/ Mazda that treads the fine line between extremes.

 

[bmichels]

Quote:

For me too the Phillips DL92 is my go to DL92, it has the depth and weight of the Mullards but with a little more detail and dynamics. I am finding my favorite combination so far in terms of sheer musical enjoyment is the Phillips/Mazda combo.

I too have found like GG I have favorites, I find it a moveable feast though as it depends on the mood I am in when listening. Sometimes I am in the mood for slightly darker tonal textures so the Mullards come to the for, sometimes light and airy and my German tubes enter the picture but for overall it has to be so far the Phillips/ Mazda that treads the fine line between extremes.

 
Phillips/Mazda combo your prefered combo ?  I thought that it was Philips/Mullard DF91 !
 
I Am looking forward testing my Philips DL92 with those "very special" Mullard DF91 that I have on order.  Indeed I found a set of 2 "Mullard WITH tiny holes" : 
 

 
 
 
 
 
PS : Are the Mazda hard to find ? 

 

[bmichels]

Quote:

They do both DL92 and DF91. Mullards go really well with these tubes as do Phillips in either stage but I think my favorites are Mullard or Phillips DL92/Radiotechnique DF91

 
Ian, are those " RT  1T4 "  the same as the Radiotechnique DF91 that you recommend ? 
 

 

[ianmedium]

As I said the sound preference depends on the mood I am in, I really like the Mullards in the DF91 stage, they are to my ears a bit more solid sounding where as the Mazda's to my ears have more air and sweetness but I would recommend the Mullards any day, lovely tubes and remember something I said way back and will repeat here again.

The ultimate best is the one you like the most rather than what I like. Seeing as these are all pretty cheap I think it fun to experiment and find your sound, that is why I always try to say "for my tastes" when I mention tubes

Those are the Radiotechniques. I really like the sound of French tubes, they have a sweetness to them balanced with air and depth which make them a great all round tube. If you cannot find the Mazda then the Ciftie is identical in sound.

I keep seeing that Mullard with the holes in Andy said his friend who owns Mullard magic said there is no sound difference between them and the non holed variety but I do love the look, if he had two I would have pounced on them!

Lastly, there are sound differences between tubes but I want to emphasize that for me it is more about the different icing colour on the cake rather than the cake itself.

All of the tubes including the stock tubes.. Especially the stock tubes Shikada San now ships with the amp, are lovely sounding tubes, changing them is just the ability to tailor the last ounce of sound to your personal requirements. For me it's like equalization without buggering up the frequencies!

 

[GermanGuy]

bmichels - i can not answer your question, but i always have mentioned excellent combos as dream set (most neutral, for rock, ...) and this time .. because of the  sound stage or the rft df97 - philco 1s4 because it's a  warm and relaxing sound without missing bite, highs, detail.
 
i never have listened to a fostex th900, so if you like the mullard philips combo as ianmedium does, you may like the rft df97 - philco 1s4 combo. the best thing is if you compare my impressions of a tube combo with your impression of the same combo, so finding the general difference between my and your sound preferences. i think i prefer a slightly less warm sound, so when describing a tube combo as to warm sounding for me it may just beeing the right one for you.
 
and ianmedium is absolutely right, it's also a question of your mood, i often change tubes depending on that.

 

[GermanGuy]

btw, there is a seller always selling 8 or 16 radiotechnique dl92 but you have to bid for, but after i sent this seller an email, now on ebay he also sells sets of four rt dl92 for about 12 euro. i already have ordered four tubes.

 

[GermanGuy]

Quote:

I am really looking forward to hearing your thoughts on these ones!

Just a question for those who purchased the "stamp" Brimars, how quickly did they get to you? He shipped mine on Monday so hopefully they will be here around the same time as the amp!

i think the brimars needed two weeks until arrived.
 
the rft df97 - orion 3s4t (in powersave mode) combo is really nice sounding, unspectacular, detailed, spacious, bass is slightly less powerfull, the combo may be not that recommended for a bass orgy when in powersave mode, but a great allrounder, you will miss nothing, no harshness, relaxing, you can listen for hours, sounds great and is excellent for low volume listening.
 
in general all dl92 i tested in power save mode have slightly more soundstage and cleaner sound but then at the same time slightly less bass and bass power and impact. switching between normal and powersave mode is like switching between a good 3 way loudspeaker and a more audiophile british 2 way monitor / loudspeaker like my proac tablette.
 
but not to forget, at the moment i listen to dire straits, love over gold, and while the combo is great sounding (3s4t in powersave mode, only one heater part on) it needs just one third of the power for heating than a standard tube set, only 100mA in total for all four tubes instead of 300mA, so highly recommended for portable use, i think the runtime could at least be doubled, will measure this next weekend.
 
edit:
 
after now more than four hours of burn-in the orion 3s4t and so the combo has nicely settled. i am at the moment listening to jennifer warnes - famous blue raincoat - this time in normal mode, no powersave, and this really makes a big difference for the bass.
 
bass impact, depth and texture is greatly improved (at the cost of 50mA), but even now only half the power needed for heating in comparison to a standard tube set while playing in at least in the same leaque as other top combos but outstanding soundstage, imaging, texture, detail!
 
highly recommended tube combo and i think this combo herewith will be declared as my standard / universal 'to go' tube combo with superior sound AND great power saving potential.

 

[GermanGuy]

okay, to have a real estimation of the runtime of the amp with different tube combos i opened the amp, desoldered the plus pole of the battery to connect a multimeter to measure the real current needed while music was playing at medium level and calculated the runtime based on shikada-san's information of about seven hours with a standard tube set:
 
df91 - dl92 - 240 mA - 7 hours
df96 - dl92 - 220mA - 8 hours
df97 - 3s4t - 215 mA - 8 hours
 
dl92 / 3s4t in powersave mode:
 
df97 - dl92 - 140 mA - 12 hours
df97 - 3s4t - 140 mA - 12 hours
 
- the power consumption measured is nearly independent of the volume of the music
- a significant part of the power consumption is needed for grid and anode voltage and current
 
at the moment i wonder if the orion 3s4t are really 3s4t types, but i seems so as the results and differences with the 1l33 are similar small.
 
so if you want a runtime of about 12 hours (nevertheless a significant improvement) you can achieve this using df96 and dl92 tubes cutting pin 1 of the dl92 tubes (good to own at least four of the same type and manufacturer when doing that).