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Analog Squared Paper Discussion Thread. - Page 131

post #1951 of 3712
GG, thanks so much for doing that. The green looks lovely indeed, I am so glad I went for that option.

Also, Shikada san said he will do a video on his youtube channel soon on how to degauss the transformers. He is working on a tool to help with this but apparently this is an important thing to do occasionally so as to maintain performance of the am at peak potential.

Perhaps you know a way GG?
post #1952 of 3712

i know this phenomenon more from power transformers (but spent some minutes searching the web), so


i at the moment do not see why shikada-san sees a problem here, but i am sure he knows why so i wiil follow and do whatever he recommends.


normally power transformers can be magnetized when switched off, because the magnetic field always has a direction depending on the phase of the ac current, so exactly sitched off when the ac voltage is 0 volt, magnetic field has had a direction so magnetizing the transformer core in one direction not reversed by the following inverted phase.


but transformer cores are made of electrical steel




not that easy to permanently magnetize.


to demagnetize a transformer core you have to apply a


- alternating magnetic field with a frequency in the range the core can follow the field changes starting with high field strength getting lower and lower until beeing zero


- a signal with the same properties inducing a field into the core


so for the tu-05 for example:


- in general turn volume to zero before switching off to avoid thus induced magnetization


- (headphone or two resistors connected to the output) playing a similar signal, for example sinus waves of some 100 hertz of decreasing volume, made for example with a software frequency generator


- maybe playing pink noise at high volume (mentioned in a german tube forum)


- playing such a signal with another player or amp connecting the output signal of the player / amp to the output (yes) of the tu-05 (tu-05 power off, no tubes, but then some resistors have to be applied on the other side of the transformers) (hey - this will be the tu-05 impedance switch / demagnetizer mod because the impedance switch is exactly connected to this side of the transformers)




in the second sentence i accidently wrote 'i knows why' and have corrected this in the obviously correct 'he knows why'.


have removed all this typing errors.

Edited by GermanGuy - 9/3/13 at 12:38pm
post #1953 of 3712
The turning the volume to zero is something he has suggested in the past and I have conveyed here on the forum. All very useful information, thank you GG.
post #1954 of 3712

thinking about the wooden side panels i just had a much better idea!


the tu-05 wooden side panel mod has shown, that something can be mounted on both sides of the tu-05.


so why not making two aluminium side panels as extension boxes for the tu-05 resulting in the




and a




i think of two about 2cm thick, mountable side panels


- with a strong power supply with lots of capacitors


- with a battery pack at least five times the capacity of the internal battery.


what do you think?

Edited by GermanGuy - 9/1/13 at 2:21pm
post #1955 of 3712
Originally Posted by GermanGuy View Post

i am not that good using gimp, but what do you think?




Now this is fantastic. I would totally send my amp back to Shikada-san for this mod. And believe me, it is not easy to pry this amp from my hands.

post #1956 of 3712

Currently up to page 62 tongue.gif Shikada san is so talented.

Originally Posted by ianmedium View Post

You can use the amp anywhere though us mad people love to experiment with isolation and such which does make a small difference the amp can be used anywhere. You should see the looks I get when I take it to my local coffee shop to listen, especially when the tubes are exposed!

In my experience you get around 7 hours from the batteries which is for me more than enough for my daily listening needs.


Size and weight does not concern me (any new amp will only be lying on the bed or sofa anyway). Equally I want it to be sensible proportions but the TU-05 is still fine in that respect. Does not seem to be much in the way of 05 vs 06 SQ impressions though apart from Anak. If I do choose to order I will enquire about custom UK power supply needs as I am not resourceful like German Guy (kudos on the cleaning tool also)


What tubes are people using for the TUR-06? 

post #1957 of 3712

just got shikada-san's offer for a large black housing and some additional parts and 2nd battery !!!


so the vu meter mod can de done!



Edited by GermanGuy - 9/3/13 at 4:45am
post #1958 of 3712

today the four radiotechnique DL92 and the four MAZDA DF92 (DF92, no typing error) arrived.


to have the fun to listen to an absolutely new tube combo with no burn-in i plugged them into the tu-05, but before again checking the datasheets of both the df91 and df92 tubes.


as expected or at least hoped, the df92 works (amp not exploding, no funny smell, no hot glowing tubes, nice sound, no distortion or whatever).


i have started to read and learn more about tube biasing, the only risks that may happen


- (but more related to power output tubes) - damaging the tube itself and / or parts of the amp,

- (related to all tubes) - decreased lifetime (but now working at least for ten minutes, so lets wait and see).


it's funny that even now after only ten minutes of listening soundstage, texture and air are clearly improved, improving from minute to minute the first ten minutes, seems everything has reached operating temperature now, so lets wait and not see but listen.


p.s. as both tube types are french production ones, for burn-in at the moment i am listening to jean michelle jarre - equinoxe

Edited by GermanGuy - 9/2/13 at 11:25am
post #1959 of 3712

i have updated my tu-05 tube compatibility list, also added some explanations:



Edited by GermanGuy - 9/3/13 at 12:41pm
post #1960 of 3712

I have a question. What brands and length of m2m cable that you guys use with TU-05 or TUR-06. I'm need to find one for my upcoming TUR-06.

post #1961 of 3712
I have had good success with Cardas and Kimbers GQ-MINI-CU I also was given a Nordost clone cable that I think is copper with silver plate and that sounds lovely as well though I am not sure where that came from.

I am seriously thinking of the GQ-MINI-HB as that has two strands of copper and two of silver and I have a feeling the balance will be good.

In truth though I find the Cardas fairly transparent and also very user friendly as it is very flexible.
post #1962 of 3712

Phew... what a relief.

After being held in several weeks, the local custom decided to release some of my packages.


Here's what arrived today. Yeaaah.... beerchug.gif


GG, now it's confirm your package has been arrived save and sound. Thanks a lot for that.

So, for those who are lived in my region and interested in the tube cleaning kits, you can buzz me now.


Edited by Boringer - 9/3/13 at 7:11am
post #1963 of 3712
Originally Posted by GermanGuy View Post

just got shikada-san's offer for a large black housing and some additional parts and 2nd battery !!!


so the vu meter mod can de done!




Wow... I'm looking forward for the result. It will be fantastic...!

post #1964 of 3712
What Boringer said! Now, this has to be documented every step for our delectation please GG!
post #1965 of 3712

okay, firstly i thought of a big surprise, but for you to whet your appetite, here are the modifications i have planned (but have to ask shikada-san first if he is willing so sell me a second internal power supply board and a second bias battery case and batteries, but assuming he will):


at the moment it is not clear and if i really want to integrate the vu meters:


- because of the space needed for the sound relevant modifications

- because they destroy shikada-san's great and unique design and i think even a modded tu-05 should be recognized as beeing a tu-05

- because with vu meters the amp can only placed horizontally


(okay, if enough space left .... have to think about it)


all switches, inputs, outputs, volume knob will be on the front or rear side of the frame:


- no sidepanel switches

- i have not decided yet if to use the smaller or longer side as front panel side


before assembling the parts in the new housing / case i will make an internal sub-frame:


- everything can be mounted on that sub-frame

- the sub-frame is mounted on the housing's frame

- both sidepanels can be removed

- mounting and recableling is much easier

- power lines can better separated from signal lines


the reassembled amp will be a completely separated double mono design:


- i will completely separate left and right channel 

- cutting and reassembling all electronic parts under the tubes where nessesary so that there is absolutely no connection between left and right channel

- providing a second internal power supply pcb to have completely separated grid and anode and heatern and led power for both left and right channel

- providing a second battery with own charger /power input jack

- providing a 4 pin mini xlr input

- providing a 4 pin xlr output

- providing a switch to select xlr or 6.3 mm headphone out connecting the two output pins of the output transformers normally always both connected to the ground pin of the 6.3 mm headphone jack

- providing a switch to connect ground between left and right channel when using standard 3.5 mm input


as a result:


- headphones can be driven in balanced mode

- balanced sources can be connected

- better channel separation

- less crosstalk

- improved power supply for heavy bass pulses

- battery runtime doubled, up to 24 hours with df96's tubes and dl92 tubes in powersave mode 


another result is that the dl93 tubes can be used:


- 200 mA heater current now possible

- up to 0.6 watt output per channel (but depends also on the grid/ anode voltage, so finally has to be measured)


to use this potential:


- i will provide 4 speaker output jacks to connect high efficient loudspeakers


to add some flexibility i will integrate an (already selected):


- internal  24 bit 96 KHz high quality usb dac

- usb port

- input selector switch (line in, dac)


other mods / switches to be provided:


- power on/off

- charging on/off

- powersave mode on/off

- led lights on/off

- impedance switch (low, med, high) for ALL possible impedance settings, not only two


status led's:


- power save mode

- power on led


any wishes or comments are welcome!

Edited by GermanGuy - 9/3/13 at 3:44pm
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