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Analog Squared Paper Discussion Thread.
Mar 11, 2014 at 6:39 PM Post #3,226 of 3,813
i am such a dummy - wanted to get this impedance switch correctly working so replacing it, had additional switches from shikada san, tested the new switches and saw, that i had used the power on/off switch as impedance switch and the impedance switch (the black one) as power on switch, BUT the black impedance switch is a real toggle switch while the power on switch (the red one) is only a on/off switch, so the third pair of contacts is not connected.
 
had to unsolder all the wires, mount the new switches in the correct positions and then solder all the wires again, but now the impedance switch is working.
 
so now i only have to make the third front hole somewhat wider to add a lumberg 3.5mm output jack and maybe change the impedance (at the moment low/middle) to middle/high to have the amp ready.
 
Mar 12, 2014 at 6:22 PM Post #3,227 of 3,813
nice...isn't it ?  but unfortunately not for TU-05...
 

 
Mar 12, 2014 at 9:47 PM Post #3,228 of 3,813
I'd like to get assistance from you chaps with tech skills in amp design about my TUR-06 noise issue.
 
According to Shikada-san he mentioned there was no issue in the power circuit. The issue he found was in the use of the SF tubes. Since the current consumption of the SF is 1/2 of the regular 1T4, the DD power supply (?? What's DD?) is "unstable".
 
I have 2 options :-
 
1) he mods my TUR-06 to make it suitable for SF (but for SF only, meaning I can't switch back to 1T4's)
or
2) Put in an advanced LC filter to reduce noise
 
Naturally I'm more interested in (2) since it doesn't limit what tubes I can use but I'm interested in more info about (2). The questions I have for this option are :-

1) What's LC filter?
2) What's the impact of LC filter?
3) Will I be able to have a versatile amp that can be used for both low impedance IEMs and mid/high impedance headphones with thie LC filter in place?
4) Can I use any 1T4 & 1T4SF tubes with this LC filter in place?
 
Can someone with tube amp knowledge please assist me in answering these questions?
 
Mar 13, 2014 at 1:33 AM Post #3,229 of 3,813
If Shikada ask me those questions, I will go for a solution that will be best for 1t4, df 96 tubes. I find them to be easier to find and sound beautiful too. I don't know anything about sf tube though. But If sf tubes sounds best for you maybe you should go for it. Or maybe can ask Shikada to supply you 1t4 tube that not make any noise and sound good too on your tur06.
 
Last couple of days my tur06 also starting to make noisier background noise even it was paired with the radiotechnique 1t4 tube. I had to make a gentle tap on the amp to make it more silent.. and funny it works but then it start to get noisy again after a minute or two.. Ok these annoying noise enough to make me open the tur06 case and see what that can be the problem. Everything seems to be fine. What i did just turn the battery over upside down trying to keep out the battery cable to touch any component on the tur06. I also try to clean the tube pin connectors using my airbrush.Then i tried tube rolling on the amp. And guess what my df96 phillip tube suddenly has the blackest background of all. there still a very tiny noise but i can live with it.
 
sidenote:  Before this i have tried my grinder and dremel to clean my tube. And this is not a good idea at all..
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Mar 13, 2014 at 2:01 AM Post #3,230 of 3,813
Funnily Shikada-san replied to my questions 2 hrs ago. It seems the LC filter is the way to go as it gives me flexibility to whatever tube I wanna use - 1T4 or 1T4SF (I've never tried DF96, they're compatible?). It also has no impact to gain which is great news 'cos it means I can use with both my FitEar CIEMs and with my Alpha Dogs orthos (but I probably have to open up the TUR-06 to change the gain).
 
The 1T4SF is the same as the 1T4 but has 1/2 the heater coil length of the 1T4 so apparently it consumes less current & power. I heard about the Fujitsu Ten 1T4SFs here from Ianmedium as it was recommended to him by Shikada-san. However I think that was meant to be for the TU-05b - I just assumed that it'll be just as beneficial for the TUR-06 too (and my 1T4SF's aren't Fujitsu but NEC). They're cheap anyway so not no harm in trying - just finding them were hard.
 
Mar 13, 2014 at 2:28 AM Post #3,231 of 3,813
Mar 13, 2014 at 4:57 AM Post #3,232 of 3,813
@Anakchan:
 
an LC-FIlter is the combination of an inductance and a capacitor, the (C)LC-filter stages can be seen on the internal power supply board (this two electrolyte capacitors with added small capacitors together with the inductance inbetween (this black .104 and .221. parts). they work as low pass filters to kill hum/noise and remove the switching frequencies of the dc/dc converters from the power lines.
 
i think the easiest solution for you could be to just add a small resistor consuming 25 mAmpere directly connected to the filament / heater pins (pin1 and pin7) of your SF tubes, so when inserting the SF tubes the internal power supply will "see" normal 50mA tubes and has to deliver 50mA per tube so may be more stable then:
 

 
 
i have nice and small 7pin tube adaptors that also could be used to connect a resistors and a tube socket to so only two adaptors with resistor and socket instead of soldering something to the tube pins (just 75 european cent per piece + resistor + socket):
 

 
 
resistor should be 1.4 volt / 0.025 Ampere = 56 Ohm.
 
this should work if the unstability of the DD power supply is related to the too low current (in fact the filament power is provided by an integrated circuit DC/DC Step Down Converter).
 
if this works it should also be possible to add the resistors and a switch to switch the connection of the resistors on / off internally.
 
if the unstability is related to the smaller inductance of the smaller SF filament this may not work.
 
for my modded amp i in fact have added additional LC and RC filter stages on two boards to be connected between internal power supply and tube amp internal power connector, should be very easy to make a small additional board with an additional LC filter stage for the tu-06 as there is enough space, so connecting the five pin out of the internal power supply board to such a board and then providing the same connector to connect the added filter board to the tu-06 amp (as i have done for my modded tu-05).
 
maybe also shikada san can provide you with such a small filter PCB board just adding the needed LC filters so you could just connect the board between internal power supply board and amp, so your Option 2 can be prepared by shikada san without sending the amp to him!
 
okay, i will modify two df96 tubes with a resistor to test and post a picture here for you to see how this could be done.
 
you could ask shikada san to test if a 56 ohm resistor in parallel to the filament pins of the tube(s) is enough to solve the problem.
 
this modification can be done by directly soldering the resistor to the tube pins.
 
i will check the JRC2392 step down converter data sheet if there is any recommendation for LC filter for low current use.
 
btw, just for clarification:
 
Tube: DF91, 1T4, 1U4, DF904 - 50mA filament current (no problem)
Tube: DF96, 1T4T, 1T4SF (DF97, pin 4 and 5 connected) - 25mA filament current (problem)
 
Mar 13, 2014 at 5:44 AM Post #3,233 of 3,813
germanguy said:
  @Anakchan:
 
an LC-FIlter is the combination of an inductance and a capacitor, the (C)LC-filter stages can be seen on the internal power supply board (this two electrolyte capacitors with added small capacitors together with the inductance inbetween (this black .104 and .221. parts). they work as low pass filters to kill hum/noise and remove the switching frequencies of the dc/dc converters from the power lines.
 
i think the easiest solution for you could be to just add a small resistor consuming 25 mAmpere directly connected to the filament / heater pins (pin1 and pin7) of your SF tubes, so when inserting the SF tubes the internal power supply will "see" normal 50mA tubes and has to deliver 50mA per tube so may be more stable then:
 

 
 
i have nice and small 7pin tube adaptors that also could be used to connect a resistors and a tube socket to so only two adaptors with resistor and socket instead of soldering something to the tube pins (just 75 european cent per piece + resistor + socket):
 

 
 
resistor should be 1.4 volt / 0.025 Ampere = 56 Ohm.
 
this should work if the unstability of the DD power supply is related to the too low current (in fact the filament power is provided by an integrated circuit DC/DC Step Down Converter).
 
if the unstability is related to the smaller inductance of the smaller SF filament this may not work.
 
for my modded amp i in fact have added additional LC and RC filter stages on two boards to be connected between internal power supply and tube amp internal power connector, should be very easy to make a small additional board with an additional LC filter stage for the tu-06 as there is enough space, so connecting the five pin out of the internal power supply board to such a board and then providing the same connector to connect the added filter board to the tu-06 amp (as i have done for my modded tu-05).
 
maybe also shikada san can provide you with such a small filter PCB board just adding the needed LC filters so you could just connect the board between internal power supply board and amp, so your Option 2 can be prepared by shikada san without sending the amp to him!
 
okay, i will modify two df96 tubes with a resistor to test and post a picture here for you to see how this could be done.
 
you could ask shikada san to test if a 56 ohm resistor in parallel to the filament pins of the tube(s) is enough to solve the problem.
 
this modification can be done by directly soldering the resistor to the tube pins.
 
i will check the JRC2392 step down converter data sheet if there is any recommendation for LC filter for low current use.
 
btw, just for clarification:
 
Tube: DF91, 1T4, 1U4, DF904 - 50mA filament current (no problem)
Tube: DF96, 1T4T, 1T4SF (DF97, pin 4 and 5 connected) - 25mA filament current (problem)
Click to expand...

 
Thanks for the information GG. I'm gonna need to digest all this :D. Actually Shikada-san already has my TUR-06 which I left with him after the Fujiya show back last month. He said that the TUR-06 has room to put in this LC filter so maybe he is already thinking of a little board?
 
Mar 13, 2014 at 5:52 AM Post #3,234 of 3,813
Okay, just saw your second post so the problem is solved. hope you get your amp back as soon as possible to enjoy listening again!
 
P.S. you could ask shikada san to connect pin4 and pin5 of the tube sockets internally because then you also can use the excellent sounding DF97 tubes !!!
 
in the case of the other tubes mentioned here g3 (g3 = pin4 in the case of the DF97 tube)  and pin5 are connected internally, for the DF97 this connection is not provided internally so has to be provided connecting the pin4 and pin 5 of the tube socket, but then they work and sound excellent. this modification is fully compatible with all other compatible tubes, where pin4 is not used and g3 is directly tube internally connected to pin5.
 
Mar 13, 2014 at 6:39 AM Post #3,236 of 3,813
Mar 14, 2014 at 1:27 AM Post #3,237 of 3,813

Heads up. 14th March 2014 2 p.m. JST

 
It seems the Analog Squared Paper web online ordering system had a glitch.
 
 

Notice:

 
If anyone made an order in March but didn't receive any answer from Shikada-san, please mail him on analog2p@gmail.com as per his Facebook. Further information can be found there.
 
Mar 14, 2014 at 6:43 AM Post #3,238 of 3,813
Ok guys today i am a very happy man because I just received my telefunken diamond base tubes. For this tube i just clean it with alcohol and tissue, the pins are not sparkling clean but they are clean enough i hope.
 
Okay as for sound.. Oh my.. just right the moment i turn the music on. It is the same feeling when I listen to my tur06 for the first time.
I listen to Ingram Washington album which is only 16 bit. The vocal is so soft but powerful (i always feel that df96 tubes have better power than the it4), lushfull with very good timbre and singer character voice are shown.. all the instruments including the cymbal sound so intimate, weighty, full dynamics and real. and the bass are the best i have heard from the tur06 so far. just right amount of everything.. detail retrieval also the best among my other tubes. Sorry for my limited language but they are really what i feel.
I kinda get the same feeling as when listening to a home speakers.. they really soft but full of detail and so intimate with unlimited three dimensional space of sound. I wonder are all tube amp can sound this good? even my df96 philips sound much less lively. I can't believe i said that because they were my best tube so far.
 
There is a little buzzing noise at the background. but i am pretty sure they just need a little more time to settling in because sometimes the buzzing are completely gone.
 
And my setup was hippo biscuit and fad heaven 2 with copper m2m.
 
I will post more impression when my ak240 come. hopefully in two weeks time.
Will post some pictures tonight!
Special thank to GG for helping me in getting this incredible tubes. owe you one GG.
beerchug.gif

 
Mar 14, 2014 at 7:58 AM Post #3,239 of 3,813
Friday flash-mob of Beethoven's `Ode to Joy' played by an "impromptu" orchestra. Lovely inspiring piece, so turn up the volume and enjoy. 
 
 
 
Mar 14, 2014 at 10:00 AM Post #3,240 of 3,813

 

 

 
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