Rangemaster clone starts gradually hissig after a while

[yeeshkul]

I have a strange day today - 2 noise issues. After that one with Memory Man i noticed that my Rangemaster clone starts gradually hissing as am using it.
When i turn it off for about 5 min, it becomes almost silent again(just the common, slight, almost unaudible hiss) but once turned on again the hiss is back in about a minute - slowly, gradually, up the level when it is really awfull. Can it be the transistor?
Unlike in case of the Memory Man, here the hiss turns off completely when i unplug the input jack...

[blanik]

change the battery?

[yeeshkul]

it has still 9.15V. Can battery cause the hiss?

[mac]

I have some AC128s that never seem to reach a steady state when performing RG test. If you socketed your transistor you could try using another.


mac

[yeeshkul]

I am affraid i will have to. I used Matsushita and it seemed to be perfect - very little leaking. 
But because the hiss kicks in gradually i guess it has to have something to do with temperature...

[yeeshkul]

It's really strange. I just take out the input jack (turn off battery) for a few seconds and back and hiss is gone for a few seconds and then it slowly comes back.

[mac]

I have hundreds of Matsushitas and I had trashed only one or two.
I should test it with RG method to see if it stabilizes after a while, and if there is a change if you turn it off and on again.

[petemoore]

  Different transistor will tell a story I bet.
  Hard to say if thermal runaway from current being fed through the tranny is causing the hiss, which is often enough associated with Ge tranny's and RM's.

[yeeshkul]

I have hundreds of Matsushitas and I had trashed only one or two.

Oh yes, the one of mine seems to be great quallity but - as i say - the hiss comes after 5-20(!)minutes when it's permanently turned on. It's sneaky as hell. 
I'm gonna buy a couple more today and refer on results.

By the way Ge diode stabilising didn't bring any results 

Thanks guys!

[yeeshkul]

I have hundreds of Matsushitas and I had trashed only one or two.

Oh yes, the one of mine seemed to be great quallity but - as i say - the hiss comes after 5-20(!)minutes when it's permanently turned on. It's sneaky as hell. 
I'm gonna buy a couple more today and refer on results.

By the way Ge diode stabilising didn't bring any results 

Thanks guys!

[yeeshkul]

i changed transistor and the hiss is gone  . you were right ..

[mac]

BTW, what matsushita are you using?
The best sounding transistors in my can are the 2SA101/102 [C] or [D]. Even better than 2SB172/175/176.

[R.G.]

I'll say it again.

Germanium transistors are so inconsistent that saying that one type number is better than another type number is much like saying that only blonde girls are good looking. None of us, including me, has access to enough germanium devices of any type number to profile them for which type number is good or bad. We are all grubbing around in the weeds looking for leftover 30+ year old transistors that didn't get used or dumped in a landfill. In many cases, what we find are what was left over when all of the good devices were tested out of a batch of transistors and not used. The type number on a germanium is a hint, a whisper of a promise, nothing more.

[aron]

BTW: R.G. Thanks again for the Rangemaster article. I'm building another one in a small round can that I got from one of the members.

Should be fun to use!

[yeeshkul]

In the end the sweetest sound i found (in my collection) comes from an old Czech Tesla GC510 device (hfe ~ 65). I don't wanna reccomend them that much though since most of them are leaky and hyper unstable, hehehe.

[mac]

RG,
I bought matsushitas, ie 2sb176, or toshibas, ie 2sb56, from different sources here in Arg and in Brazil & Uruguay and they seem to be consistent in average gain, leakage, reliability, look and sound. This is why I advice others to try them, but only of these two brands!. I also posted photos because of this facts. I was looking for them in other countries but it seems that there was a fever for japs ge in mine. Also, as there is nothing here like mouser or radioshack, the small electronic stores, old catholic schools tech labs and  old technicians still have lots of sealed bags of japs ge and vintage tubes.

On the other hand my Texas Instrument 2n388s are out of specs, lower gain than expected,  but very good sounding. Once I bought 2sb175 non-matsushitas and they suxs. ACxxx, generic stuff, well...

This a lottery... In general terms I agree with you: two different brand but same type ge will be a lot different.

Or maybe it's me that love blonde girls of any kind... except XL type jeje