right, that. Better a good bypass Mundorf type, without exaggerating the costs. That super cap allows you to eliminate the harmful servo circuit, throw it away
the problem, one of many, of 108 or its revisions, is the selection of the assets which in a similar scheme is basular.
The stage of entry becomes very important and selecting 5551 and 5401 is a problem.
Furthermore, it is a mistake not to join them, not to glue them, but to keep them close and very close.
The dual case with NPN and PNP of these EMZ1 FHA families are interesting, where the selection is almost ideal and solves some problems.
Of course the pair 5551 and 5401 sounds good
The stage of entry becomes very important and selecting 5551 and 5401 is a problem.
Furthermore, it is a mistake not to join them, not to glue them, but to keep them close and very close.
The dual case with NPN and PNP of these EMZ1 FHA families are interesting, where the selection is almost ideal and solves some problems.
Of course the pair 5551 and 5401 sounds good
yes, it would be better to buy it to assemble: the Chinese selection of assets is very optimistic
then the powers which are enough to discuss.
We did everything stabilized, it costs less and is much better
the maxi transformers and the large filter capacities of the original, difficult to understand what they are used for if not to fill the scayola and try to justify the price of the final: tried to remove 4 of the 6 BC 22000/63 volts per channel and tried to use two 300VA transformers and canbia just nothing
We did everything stabilized, it costs less and is much better
the maxi transformers and the large filter capacities of the original, difficult to understand what they are used for if not to fill the scayola and try to justify the price of the final: tried to remove 4 of the 6 BC 22000/63 volts per channel and tried to use two 300VA transformers and canbia just nothing
yes, but they must be polarized correctly by changing the zener and resistance value, which was perhaps done in that card. We made ourselves a 4 couples per channel
I was planning to keep the 5551 and 5401 as close as possible. I'm waiting for delivery of two torus transformers(400w) with blind coil (AC 2*40v) and 12 capacitors(6 per channel) 15000mf each
I'm thinking of removing of couple of transistors ( leave just 4 instead of 6, somehow I believe that the quality of sound would be better with 4) when I get all of the components
if I can allow myself:
don't waste money on so many expensive filter caps.
with this 1 or 2 pair circuit, two top quality caps per channel and a 300 VA transformer are enough
TRUE!
2 couples or 4 couples, but already 2 are enough and they advance, 3 I don't understand them
A good purchase
and I am also convinced that waiting three months will pay off with great satisfaction.Contrary to common belief, quality control over this type of production of Chinese origin has grown so much and is now almost equal or even better than Western standards.
The suggestions already indicated by Domenico, I agree with them.
Even if the offset stabilization servo circuit, it was the thing that I personally eliminated almost immediately after a short listening test (in my case, however, it was a separate board and not integrated as in your case) I would suggest you to try it as you received it and then decide calmly whether to perform a by-pass (to be studied carefully in the case of your board) or not.
In my opinion, it is also essential to physically couple the two pairs of 2N5401/2N5551 (which I even coupled and selected for HFE after having purchased 50 pieces each) transistors with thermal paste and a centimetre of heat shrink sleeve.
Don't deny to check the working voltage of the two Zener Z1 and Z2 diodes served to the Q90 and Q100 transistors, to understand if the 5.1 Vdc version (insufficient to correctly polarize the three pairs of power amps) or two with a higher value have been mounted.
Their ideal value to avoid the risk of saturation Q9 and Q10 in the signal peaks, is 6.2 Vdc in case of a supply voltage of about 56/60 Vdc.
As for the two 3.3, uF input capacitors, personally and against all bets, instead of using two plastic film capacitors I used two NICHICON Muse Fine Gold FG Series 10 uF/50V electrolytic capacitors with impeccable musical results.
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Ultra Legione,
Thank you for the advice. As soon as I get the missing part, I will follow your advice in connecting it all together. Can't wait to hear the sound
Thank you for the advice. As soon as I get the missing part, I will follow your advice in connecting it all together. Can't wait to hear the sound
At the entrance instead of the pair 5551 and 5401 try a dual smd chip with PNP and NPN similar to what I have indicated: they are phenomenal and the offset is better controlled
Certainly.
I think it is better to always look at quality than the quantity of microfarads.
Even better to eliminate them, you save and you have a much better stabilized.
we consider that the 108 is not a lightning bolt nor a low and medium low range phenomenon
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SMD chip mounting
Are you referring to the EMZ1 FHA?
Can one replace a pair of 5551 and 5401 straight out? Should both the input stage pairs be replaced?
Are there sockets so they can be soldered in place of TO92 transistors, or how did you make them fit the board? Picture?
Are you referring to the EMZ1 FHA?
Can one replace a pair of 5551 and 5401 straight out? Should both the input stage pairs be replaced?
Are there sockets so they can be soldered in place of TO92 transistors, or how did you make them fit the board? Picture?
Well, soldering SMD chips is always a big mess, but you can solder them with patience and attention. It is clear that one chip can give different results than another, but I can be more precise about what we used. The PNP and NPN dualchip has the sole purpose of being able to better control the offset using a multiturn trimmer. The input stage of a scheme such as 108 is very critical, much more critical than a usual differential where the choice of transistor or fet or mosfet is much more abundant