An other mod of MHZS player:
http://www.lampizator.eu/LAMPIZATOR/REFERENCES/MHZS/MHZS_CD66F.html
According to the link, the tales on new chip design is marketing bull*hit. Pitty for otherwise probably good players...
http://www.lampizator.eu/LAMPIZATOR/REFERENCES/MHZS/MHZS_CD66F.html
According to the link, the tales on new chip design is marketing bull*hit. Pitty for otherwise probably good players...
PetrL said:
you are right, forget all the marketing. For over a year we know already inside the MHZS players is a lot of fake components but al of this *hit sounds great.
The mods i have done are results of the discussions on hififever.
http://www.hififever.com/forum/viewtopic.php?t=952
http://www.hififever.com/forum/viewtopic.php?t=1573
I'm planning to start with cd66E soon. Or later. I'm a newbie with cd mods, but rather handy with soldering iron, and I think this unit is a good starting point to study modding a cd. The referred Hififever threads were a bit too much for me to follow, so I post here. 
I'm planning to take three steps to evaluate the effect of each separetely, but to take them in different order than what Koifarm showed. I'm in no hurry, and I'm especially interested in output capacitors' effect, since replacing or bypassing them seems like a common mod for many CDPs.
1st:
Replace output capacitors (C13 and C14 in pic). I'm considering Mundorf. You refer to values 2...10uF. More details or experience to share about the value?
2nd:
Up the voltage to 100V. D2...D5 replacement is just to have better diodes, but the originals would do ok as well, right?
3rd:
Getting rid of the op-amp as in 'passive mod'. Change C7 and C8.
All comments welcome.
I'm planning to take three steps to evaluate the effect of each separetely, but to take them in different order than what Koifarm showed. I'm in no hurry, and I'm especially interested in output capacitors' effect, since replacing or bypassing them seems like a common mod for many CDPs.
1st:
Replace output capacitors (C13 and C14 in pic). I'm considering Mundorf. You refer to values 2...10uF. More details or experience to share about the value?
2nd:
Up the voltage to 100V. D2...D5 replacement is just to have better diodes, but the originals would do ok as well, right?
3rd:
Getting rid of the op-amp as in 'passive mod'. Change C7 and C8.
All comments welcome.
Juuso said:I'm planning to start with cd66E soon. Or later. I'm a newbie with cd mods, but rather handy with soldering iron, and I think this unit is a good starting point to study modding a cd. The referred Hififever threads were a bit too much for me to follow, so I post here.
I'm planning to take three steps to evaluate the effect of each separetely, but to take them in different order than what Koifarm showed. I'm in no hurry, and I'm especially interested in output capacitors' effect, since replacing or bypassing them seems like a common mod for many CDPs.
1st:
Replace output capacitors (C13 and C14 in pic). I'm considering Mundorf. You refer to values 2...10uF. More details or experience to share about the value?
2nd:
Up the voltage to 100V. D2...D5 replacement is just to have better diodes, but the originals would do ok as well, right?
3rd:
Getting rid of the op-amp as in 'passive mod'. Change C7 and C8.
All comments welcome.
The value of the output capacitor needs to be 1uf or higher because together with the inputimpedance of the amp it becomes a highpass filter with cut off the subbass. 10uf is standard in the MHZS players.
Kooka said:
These prices we paid a year ago. Today the prices are almost 2 times higher. Succes has it price.
Thanks for the reply, Koifarm!
The thing is that I don't have the CDP in hand yet: I shall get it from a friend at some point soon.
a bit faster transient response.
You suggested using 0.33uF caps for C7 and C8 instead of apparently (haven't checked, since no player in hand) original 0.22uF. Why is that?
The thing is that I don't have the CDP in hand yet: I shall get it from a friend at some point soon.
I get the basic idea, but I was mere wondering about getting the value to be on the safe side, i.e. resulting in no filtering independent on the pre-amp input impedance. 10uF is probably a safe choice, since originally designed to have that, but less capacitance might bring in more caps to choose from, and maybeKoifarm said:
a bit faster transient response.You suggested using 0.33uF caps for C7 and C8 instead of apparently (haven't checked, since no player in hand) original 0.22uF. Why is that?
Juuso said:Thanks for the reply, Koifarm!
You suggested using 0.33uF caps for C7 and C8 instead of apparently (haven't checked, since no player in hand) original 0.22uF. Why is that?
The MHZS 33 has 0.22uf capacitors and the 66 or 88 has 0.47 uf on that position. Every thing higher then 0,22 uf is good. I like to use PIO capacitors in this position. I used Sprague Vitamine Q PIO's with where 0.33 uf.
Oh! I had thought that cd33 and cd66 have identical boards; that the only difference is the cd loading mechanism. Well, for C7 and C8 I shall stick with 0,47uF.Koifarm said:
Is the schematics, found on HifiFever page, valid for cd66e?
How about other (than C7 and C8) component values; are the resistor values you suggest as replacement, when doing the passive mod, suited for cd66e?
The schematic and board are the same as the 33 but the 66 has after the tubestage a extra symmetrical outputs. If you use them you can change also the opamps and capacitors in the symmetrical output. If you use the RCA output just leave the symmetrical output as it is.
The 66/88 has other output tubes ( 12ax7 ) so you do not have to change the 68K resistors but only the 33K resistors to 27K. The rest of the passive mod are the same as in the startpost
The 66/88 has other output tubes ( 12ax7 ) so you do not have to change the 68K resistors but only the 33K resistors to 27K. The rest of the passive mod are the same as in the startpost
Oh! Different tube. Ok, now it makes sense about the tubes different people were referring to: they were referring to different players. And the only difference is one capacitor value per channel? Ok. And the only change needed in resistors when removing opamp would not be bigger than that. Ok.
As a starting point.
Oh yes, the symmetrical output, or balanced, or XLR, which ever term is to be used. I had already forgotten about them. So that is after the tube stage, not in parallel to it?
I assume that they should be ok to use, "as is" even though the mods listed above are done. Or do the mods change the output from tube stage that much that some mod is a must? I mean technically.
Balanced output is probably not a clever choice in terms of sonics, if that brings back opamps to the signal path, after having just removed the opamp from the signal path with the passive mod. I mean when having option to use RCA as well. But balanced out could be modified to have tube output too. Right?
This is getting very interesting. I can't wait to have the player in hand! Thanks a lot for the replies: highly appreciated.
No way to get a real balanced ( symmetrical)output on the MHZS players. Because the DAC has no balanced output. The balanced output is generated out off a asymmetrical audiosignal. So just use the RCA output and leave the symmetrical output as it is.Juuso said:
Oh yes, the symmetrical output, or balanced, or XLR, which ever term is to be used. I had already forgotten about them. So that is after the tube stage, not in parallel to it?
I assume that they should be ok to use, "as is" even though the mods listed above are done. Or do the mods change the output from tube stage that much that some mod is a must? I mean technically.
Balanced output is probably not a clever choice in terms of sonics, if that brings back opamps to the signal path, after having just removed the opamp from the signal path with the passive mod. I mean when having option to use RCA as well. But balanced out could be modified to have tube output too. Right?
Modding the powersupply from 80 to 100V give a wider soundstage and more detail in the highs. This mod i can also recommend.
Do I *need* to change also diodes d2...d5 doing that? I mean for voltage (wattage) rating?Koifarm said:
Have done any measurements modified vs unmodified unit?
Still waiting for to get the hands on mine.
I thought I have no hurry, but now I'm wondering if I have patience to listen to the unit unmodified before doing the mods.
Yes I have. Must have.
Hi Koifarm, is this the right place to get you? I am the same mhifi from xtremeplace.
Questions, Is the 88 analog PCB compatable with the 33 beside the XLR connector? Any idea factory sell only this board? Where can I get this in China? Thinking of upgrade my 33.
Oh no, forgot the 33 using 6n3 tube so the power supply also have to change . Anyway, must able to get the board first.
Questions, Is the 88 analog PCB compatable with the 33 beside the XLR connector? Any idea factory sell only this board? Where can I get this in China? Thinking of upgrade my 33.
Oh no, forgot the 33 using 6n3 tube so the power supply also have to change
. Anyway, must able to get the board first.
Juuso said:
Do I *need* to change also diodes d2...d5 doing that? I mean for voltage (wattage) rating?
Have done any measurements modified vs unmodified unit?
Still waiting for to get the hands on mine.
I thought I have no hurry, but now I'm wondering if I have patience to listen to the unit unmodified before doing the mods.
Yes I have. Must have.
You do not need to change D2---D5. Just D1 and the capacitors C1---C4. But change D2----D5 to schottky types makes it a better power supply.
mhifi508 said:Hi Koifarm, is this the right place to get you? I am the same mhifi from xtremeplace.
Questions, Is the 88 analog PCB compatable with the 33 beside the XLR connector? Any idea factory sell only this board? Where can I get this in China? Thinking of upgrade my 33.
Oh no, forgot the 33 using 6n3 tube so the power supply also have to change
Hallo, mhifi.
For MHZS parts try to connect Alfcat on the hififever forum. He has the right connections. It is not a big upgrade to change to MHZS 66 or 88 PCB.
A bigger change/upgrade is to build in a other DAC like the HongKong Dac board. You get a complet other sound. More detail, wider staging , more dynamic but is plays less warm.
An externally hosted image should be here but it was not working when we last tested it.
Dear Nikolas,
Your pcm1742 must be ok if the connection pins are in place.
You can get this on ebay at around 4 euro/piece:
Audio Digital-To-Analog Converter IC PCM1742KE - 2 PCS on eBay (end time 18-Apr-10 15:48:10 BST)
Regards
Michalis
Folks,
You are by far not through and extreme enough.
First, connect the output from the DAC directly to the gridstopper (1K carbon composite will be nice) of the gain tube. Connect the second halve in parallel with it's own gridstopper.
I would suggest 1KOhm cathode R per section and a 1.5K common anode resistor for the gain-stage.
This gives a gain of a little over 2, just right for a little over 2V RMS output. Output Impedance is a little on the high side, at 1.5KOhm, but it is a "real" output impedance (see BAT's white paper on their "unistage" or whatever design for more) and sounds great. It gets rid of the cathode follower and of unnecessary gain and attenuation.
You cannot get more direct. Signal to grid, straight out from the anode.
Using good quality resistors in at least 2W (better 5W) is recommended.
For the coupling Cap use the best you can get. My take would be 2.2uF/250V as either diyhifisupply Obbligato Tinfoil & Polyprop Film or the Mundorf M-Cap ZN or Audyn KPSN. If you really have too much money get Audio Note Copper Foil or Silver Foil.
Ciao T
PS, I would keep the Tube Rectifier, but replace the resistors with chokes, this reduces noise and brings up the voltage too.
You are by far not through and extreme enough.
First, connect the output from the DAC directly to the gridstopper (1K carbon composite will be nice) of the gain tube. Connect the second halve in parallel with it's own gridstopper.
I would suggest 1KOhm cathode R per section and a 1.5K common anode resistor for the gain-stage.
This gives a gain of a little over 2, just right for a little over 2V RMS output. Output Impedance is a little on the high side, at 1.5KOhm, but it is a "real" output impedance (see BAT's white paper on their "unistage" or whatever design for more) and sounds great. It gets rid of the cathode follower and of unnecessary gain and attenuation.
You cannot get more direct. Signal to grid, straight out from the anode.
Using good quality resistors in at least 2W (better 5W) is recommended.
For the coupling Cap use the best you can get. My take would be 2.2uF/250V as either diyhifisupply Obbligato Tinfoil & Polyprop Film or the Mundorf M-Cap ZN or Audyn KPSN. If you really have too much money get Audio Note Copper Foil or Silver Foil.
Ciao T
PS, I would keep the Tube Rectifier, but replace the resistors with chokes, this reduces noise and brings up the voltage too.
Last edited:
Hello, I am new in this forum.
I have a MHZS cd 66, and I want to modify this.
A pair of questions, for C7 and C8, which is better, 0.33 or 0.47uF? the original is 0.47uF.
For C13 and C14( output capacitors), 2uF or ...10uF?
I put Mundorf silver oil, in all.
Resistors, 22kor 27k?, and the other two, 82k, is ok?
My english is very bad, sorry, thanks, regards.
I have a MHZS cd 66, and I want to modify this.
A pair of questions, for C7 and C8, which is better, 0.33 or 0.47uF? the original is 0.47uF.
For C13 and C14( output capacitors), 2uF or ...10uF?
I put Mundorf silver oil, in all.
Resistors, 22kor 27k?, and the other two, 82k, is ok?
My english is very bad, sorry, thanks, regards.