[bmichels]

Do I have a Problem or NO Problem ? 
 
With my new tubes, one of the 4 tubes (PHILCO on the right ) do not glow !!
 
In fact, I understood that it is rather the LED under the tube that do not glow, but.... I remember reading somewhere that thoses LED are also used by the manufacturer to indicate a problem in the tube  or circuit ? Is it true ? Do this tube has a problem ? 
 

 

[ianmedium]

Yes, you have a problem! The LED's are there for two reasons. One for visual effect as the tubes used in this amp do not generate enough heat to glow but more importantly the second reason is to show if either a tube or the circuit is not working.

I would remove the tube and try one that is officially sanctioned for use in this amp by Shikada San.

I have to say something here as there are new owners coming on board.

Whilst I think GG's efforts are wonderful and I admire his adventurous spirit he has the ability to take apart and put back together this amp so can fix problems that may occur through his experiments.

For the rest of us it is wise to remember that if we use or do anything that varies from stock we will be faced with a lengthy and probably expensive repair bill.

I cannot recommend using any tube other than those endorsed by Shikada San and quite frankly see no point In using anything other than those recommended or approved by him. This is not having a go at GG, I admire your abilities sir but I think we have to have some perspective here that doing anything with the amp that Shikada San does not give the OK for will invalidate the warranty and may cause harm to the amp.

For reference, as far as I am aware these are the only tubes that Shikada San has officially approved for use in the 05..


Voltage gain stage: 1U4/ 1T4(DF91)/ 1T4T

Power stage: 3S4(DL92)

Personally I would not use tubes that require pins removed. I just personlly would not take the risk.

I hope you have not damaged your amp in using incorrect tubes Bmichels, hopefully it is just the tube that is dead, please let us know.

 

[GermanGuy]

   
Dammned, I did not see them on the audiophonics site !  do you have a link to them to order them ? 

 
just goggle 'neutrik xlr 4pin black', then look to the pictures, is the easiest way to find products, as the pivtures are linked to the website they were published.

 

[GermanGuy]

  Do I have a Problem or NO Problem ? 
 
With my new tubes, one of the 4 tubes (PHILCO on the right ) do not glow !!
 
In fact, I understood that it is rather the LED under the tube that do not glow, but.... I remember reading somewhere that thoses LED are also used by the manufacturer to indicate a problem in the tube  or circuit ? Is it true ? Do this tube has a problem ? 
 

i would estimate that the led is the problem, if you want to verify that just put this tube in the opposite socket and vise versa.
 
also the led's are directly connected to power (so not an indicator if the tube is working, you can switch the amp on with NO tubes inserted, the led's are always glowing).
 
but i had the same problem when soldering the pins together one wire of one led was touched by the soldering iron and desoldered accidently having a loose contact!

 

[GermanGuy]

 
- For the XLR cabling I will use the same cooper cable that has been used for re-wiring my TH-900 balanced. And since the 2 (right & left) ground of the transformer output will not be connected together anymore, may be I will experience a better channel separation (if I disconnect the 1/8 jack on the front) ?  What do you think GG ?
 
 
- I may also want to do the recabling of the Input jack up to the board/tube.... ?  But here I don't know if I should also use the same Cooper cable or if another cable will make more sense ? ? ? 

 
channel separation i think would be improved by better separation of the tubes, left / right channel, separation of power supply for left and right, i would expect a slighty better control of the headphone drivers improving precision, fine detail and bass.
 
as headphone cable is often not shielded i will use single wires as twisted pairs for the input path. as silver wires are often mentioned as analytical, precise but not that warm sounding as copper, maybe you can use the same cable as your interconnect is made with.

 

[bmichels]

LED problem solved....

   it was me being SO STUPID ! 

 
Indeed, After cutting pin n°1 from the PHILCO, I did put a piece of black tape under the tube to cover the pin to avoid any risk of short circuit, and...this black tape was positioned just above the LED, blocking the light emitted by the LED !!
 
But there is one good thing coming out of this: Putting back the RCA 1U4 + Raytheron 3S4 tubes that were shipped with the unit in order to check is the problem was still there with other tubes, I was surprised to find how good the original combo was.  
 
So, when I will have tested the RFT DF97 + PHILCO 1S4  and also the mazda 1T4 + philips dl92,  i will go back to the RCA 1U4 + Raytheron 3S4 to test them again, and... it will be very funny if after all those tube rolling exercices, I come back to the original tube as my preferred combo ! 

 

[GermanGuy]

good to hear!
 
i also sometimes read through my postings of my impressions of different tube combos and listen to them, all of them have strong or not so strong points, but for me and my diy grado style headphone the rft df97 - philco 1s4 is a match made in heaven.
 
i have to say that while for the not so experienced ones if it comes to electronics the standard tubes are a natural choice as ianmedium does (and they are mentioned as standard tubes in my compatibility list), but that should not result in inducing fear to use tubes that are compatible and CAN be used without any risk.
 
it is just a matter of fact and electronic design that for example the 1s4 is not an 'incorrect' tube but after cutting pin 1 or modifying the amp with a switch for pin 1 is fully compatible, even if shikada-san had only the df91 and dl92 tubes as primary tubes in mind when designing his amp. the compatibility is independent.
 
a pin compatible tube (dl95) that works, i.e. you can listen to music, but due to too different parameters for bias, grid and anode voltage will distort has not found its way to the tube compatibility list.
 
each tube type in the tube compatibility list was at least tested for 8 hours, so even a wrong bias and so constant current flow through the outout transformers did not happen (could result in overheating up to damaging them).
 
so as i wrote as intro to my twin output mod one should know what he is doing, but there is no risk to cut pin 1 of a 1s4 tube or connecting pin 4 and 5 of a df97 tube or using a df96.

 

[ianmedium]

GG, If you could get Shikada San to sanction the use of these other tubes great, we have more choice but personally I would not do it unless the approval came from the designer of the amp himself as he knows the design inside and out. If you could ask him and he gives the OK then the amp will be covered. If he does not give the OK and a fault develops then the owner faces a large repair bill and having the amp away for an extended period of time.

I think it is great you have done all of this work and i admire it but I think it is very important to make it clear what Shikada San gives approval for in using his amp. I did this with the 1T4T and other tubes, the 1T4T is the only one he sanctioned.

 

[bmichels]

Now...can't wait for the next AK to come to pair it with the TU-05 to improve my setup !  RWAK140-S ?  

 

 

[ianmedium]

Why wait? The 120 is wonderful, just got an A+ review from The Absolute Sound!

 

[GermanGuy]

ianmedium - i think we both have the same opinion that for new owners and readers of this thread it is an important information and it is good to post this here as i also mentioned and marked the standard tubes as being a standard tube in the compatibility list and everybody has the choice to use only standard tubes as you do.
 
but we should also avoid giving the readers the feeling that there would be a risk using the other tubes mentioned here that can be used or be used with modification as there is no risk and at least i and bmichels have tested them.

 

[LFC_SL]

RWA have balanced mod as well: http://redwineaudio.com/mods/rwak120-s
 
Not much use in this thread of course but nice if you have an amp collection

 

[bmichels]

Why wait? The 120 is wonderful, just got an A+ review from The Absolute Sound!

 
I Know that the RWAK-120S is a wonderfull source, but I really feel cramped with the tiny Screen and anowed by the lousy interface. 
 
So, the next AK should at least solve those issues, and for the time being, I am happy enough with my RWAK100 to be able to wait few months.

 

[ianmedium]

The straight 120 is excellent as well, one reason why an excellent such as The Absolute Sound rates it at A+!

 

[bmichels]

Boy, those PHILCO 1S4 are titling !!  

   Just gently touching any part of the Amp, and here they go !!  never heard this before with other tubes....
 
GermanGuy: IS it specific to the PHILCO or does it mean that my set of tubes PHILCO is in bad shape ?