music111, i can not tell you the effect of your changes because you do not specify with capacitors you want to replace.
Changing the powercapacitors is very useless if you do the passive mod next.
In the link i send before are the 3 most noticeble mods i have heard in the past 3 years.
- Passiv mod( more detail and better staging)
- Change capacitors in audiopath.( less warm with softer hights)
- change anodevoltage of the tubes from 80 to 100Volt( more dynamic )
And there is the never ending story of tuberolling.
But before that you must clear with yourself what you want to change of the sound of the MHZS player. It is useless to do every mod there is if you do not have a goal.
Below the discription:
We do the following mods:
1 – Remove the opamp and filter( it calls the passive mod)
2 – Bridge and replace capacitors in the audio path.
3 – Higher the anode voltage from 80 to 100V and replace the buffercapacitors.
It all takes a hour of work, and give you much more detail, bigger staging and it is like the curtain is falling down.
1- passive mod.
C11 and C12 must be bypassed on the other side of the board and a few other points must be short. See below.
Connect the yellow points with solder tin.
Then remove the 3k9 resistors and the opamp. See below.
These are the light blue parts. And ready is the the passive mod.
It is possible that the output signal is lower then before to correct that you have to replace two resistors a channel see below.
Replace the green 33K for 22k/1/4 Watt and replace the 68K for 82K/1 watt and the output signal is higher. My recent experience is just replace the 33K for 27K and leave the 82K resistor as it is.
2- Brigde and replace the capacitors in the audio path
Replace C7 and C8( see first picture ) for PIO Capacitors of 0,27 uF or 0,33 uF. Good and cheap brands are Sprague Vitamine or Russian pio k40-2. Replace C13 and C14 ( output capacitors ) for PIO Russian 2 uF (2 x parallel 1 uF) or Neutral MKP between 2,2 uF and 10 uF like Clarity Caps APW. See below.
C11 and C12 we already bypassed in the passive mod. So we have just two capacitors a channel.
3 – Higher the anode voltage from 80 to 100V and replace the buffer capacitors.
Replace zenerdiode D1 for a 100V/min. 2 Watt type, Replace C1,C2, C3 for 220uF/160V ( Panasonic or so ). We also replace D2,D3,D4,D5 for scottky diode’s like BYW100/200.
On the other board you have to replace C4 for 220uF/160V.
This mod is only for the MHZS 33 and 66, the MHZS88 already has a higher anode voltage.
I hope this description is useful for you.
Ronny |