Dual La2a - [silent:arts] version

[waldorfcave]

maybe this is an idea?

i use jj ECC803 and 12bh7 from electroharmonix all brand new

[[silent:arts]]

Lars, I think we are on the right way

I checked different Tubes in the place of V101, and there were significant differences in overall noise, noise and hum spectrum.
sadly I can't do any FFT at home, but I used a Neutrik Minilyzer and my ears.

the Tubes I found and have tested are:

- Telefunken ECC803S (my "Stock" Tube in there)
- Valvo ECC83
- Siemens ECC83
- Sovtek 12AX7LPS
- JJ ECC83S
- JJ ECC83
- Japan 12AX7A

with the JJ ECC83S I had significant Hum and a Noise Floor of only -50 dBu. will be fun to do some real measuring at work with different tubes.
(but this will take some time ...)

do you have any other ECC83 to check ?

[waldorfcave]

no ihave no different tubes

is - 50 dbu good or worse ?

ok. then i need new tubes, which should i prefer?

great volker

[[silent:arts]]

is - 50 dbu good or worse ?

it is 17dB worse than -67dBu

ok. then i need new tubes, which should i prefer?

interesting thing is the JJ ECC83 was better than the JJ ECC83S in my little test. should be the other way in my understanding.
I have only used old tubes yet, don't know what I should recommend.

it is always handy to have some spare tubes ...

[waldorfcave]

ok.

but what should i do now

[[silent:arts]]

I will send you the V101 and V201 from my unit (but I want them back )
this way we can make sure if the hum goes away with other tubes.

[waldorfcave]

you make my day

[[silent:arts]]

I have 4 older Mallory Caps (silver cans) that someone gave to me for free. Send me you address and I will mail you 2 of them! I will use the other two on mine. I measured them with my Fluke MM and 2 came out as ~13uF and the other 2 came out as ~12uF so I will pair them up that way.

Not sure if they are good. They are new old stock but they were free ... so.

I will throw them in the post for you.

-ChuckD

received them today, thanks very much.

[waldorfcave]

Hi Volker,

received your tubes....and i´m totally shocked

now i have some hum behind -98dbfs, this far enough for me.

changed my tubes yesterday also to electro harmonix, with result of -80dbfs hum. nearly ok.

But i need this telefunken tubes

maybe somebody know where i can buy them



- oh man this thing is really crazy for me. i´ve been looking for hours for some faults.

now i know what differences are in tube

[[silent:arts]]

now i have some hum behind -98dbfs, this far enough for me.

good to hear - so it is not the PCB or your build

if you are looking for those Telefunken tubes:
ebay

ich sollte meine Altersvorsorge mal aus dem Sidechain entfernen, da tut es auch was anderes ...

[waldorfcave]

...Dann schick ich die doch lieber als versichertes Paket zu dir zurück

[bernbrue]

Lars,
just a thought. Could it be that you´ve damaged your tubes powering them up without heater voltage? Just try another set of tubes. There is a difference between Telefunken, JJ, Valvo etc. but I would give it a try. Anyway, you found a solution to your problem, that´s what counts
Bernd

[waldorfcave]

Tatta Finally

MY PHOTOLOVE STORY

[bernbrue]

Boooooooooooaaaaaaaaaaaaah,
das ist ein schickes Teil. Der könnte glatt so im Laden stehen. Glückwunsch, Lars. Die Bauzeit ist auch kaum zu unterbieten. Kabelbinder gibts ja auch ganz günstig im Baumarkt ..
Gruß
Bernd

[hugoderwolf]

Die Bilder hier sind ja viel größer als bei Logicuser.de. ;)

The wiring could indeed use some improvements. ;)