Modification of MHZS CD players

[tonimxp]

I found wrote ecc88 can work fine with V plate 150v or so.
Can ecc88 to be a alternative tube for solve my problema?

 

[McGyver]

ECC88 has different pinout and much more gain than 12AU7.

 

[tonimxp]

Second cathode resistor could be 47k/2W also.
The gain will be about 8.

I need gain =1 becouse input tube stage is already 2.2 Vrms and in out i have 2.7 Vrms

instead input opamp is 1 Vrms so opamp gain=2 or so

 

[McGyver]

You need to omit an opamp and to obtain gain of 2. Wchich is difficult to get with popular small tubes without negative feedback.
You may obtain the gain about 3 with 12B4A tube, but default power supply is insufficient.

 

[tonimxp]

This Is what already happens with the configuration of my post 177, so gain Is ok.
I also saw that at your post 18 you used ecc88 with 120V , what Is the gain in ecc88 your solution of post 18?
Thanks

 

[McGyver]

I also saw that at your post 18 you used ecc88 with 120V , what Is the gain in ecc88 your solution of post 18?
Thanks

It was eleven years ago, I do not remember it clearly enough.
When I look at it after several years, I can see that it could be done much better.

 

[tonimxp]

Aggiornamento spdif..

 

[tomw]

I wonder will this mod restore my MHZS CD88E? I was using mine as a transport only but now it outputs a high pitched sound from the spdif into my external dac. So far it's now confined as a boat anchor collecting dust. In the past, I've used it as a CD player and Lampizatored (bypassed the opamps and wired it to the tubes and output caps directly to the RCA plugs) only for that to fail as well

 

[tonimxp]

Mi chiedo che questa mod ripristinerà il mio MHZS CD88E? Stavo usando il mio solo come trasporto, ma ora emette un suono acuto dallo spdif nel mio dac esterno. Finora ora è confinato come un'ancora di una barca che raccoglie polvere. In passato, l'ho usato come lettore CD e l'ho fatto lampeggiare (ho bypassato gli amplificatori operazionali e l'ho collegato alle valvole e ai tappi di uscita direttamente alle spine RCA) solo per far fallire anche quello

Ciao Tomw, puoi fare il vassoio....

Mi chiedo che questa mod ripristinerà il mio MHZS CD88E? Stavo usando il mio solo come trasporto, ma ora emette un suono acuto dallo spdif nel mio dac esterno. Finora ora è confinato come un'ancora di una barca che raccoglie polvere. In passato, l'ho usato come lettore CD e l'ho fatto lampeggiare (ho bypassato gli amplificatori operazionali e l'ho collegato alle valvole e ai tappi di uscita direttamente alle spine RCA) solo per far fallire anche

YOU can try....It Is simply.

 

[tomw]

Ciao Tomw, puoi fare il vassoio....

YOU can try....It Is simply.

Grazie Mille, the extent of my Italian....

 

[tonimxp]

Grazie Mille, the extent of my Italian....

I meant simple and not simply .... However I suggest you replace that capacitor too (the one you see in red has already been replaced with one of the organic polymer type, excellent for digital).