Using two rectifier bridges
I asked earlier about using a transformer that has only three leads from the secondary windings and it seems that this won't do for using two rectifier bridges.
Does anybody know if it is possbile to convert the transformer to have four leads as presumably there are two secondary windings?
The output of the transformer is 24-0-24.
I asked earlier about using a transformer that has only three leads from the secondary windings and it seems that this won't do for using two rectifier bridges.
Does anybody know if it is possbile to convert the transformer to have four leads as presumably there are two secondary windings?
The output of the transformer is 24-0-24.
fedde said:
I tried them today. The Future-Active part no. was MBR201100CT, schottky barrier rectifiers,20A 100V.
Not even a match for both MUR860 and MUR1520. While Schottky didn't sound bad, they presented sort of harshness which was not really nice to listen to when comparing to other diodes. MUR860 is more laid back and a bit slower sounding comparing to MUR1520, and 1520 has a bit more harshness and at the same time, an extra detail, which might be appealing to some. I didn't make my choices yet.
But I can stress one thing for sure. The sound of this amplifier is very dependant on rectifier you will use. You can either make an average amp or a great sounding amp (providing other components are wisely chosen as well).
Peter Daniel said:
Not even a match for both MUR860 and MUR1520. While Schottky didn't sound bad, they presented sort of harshness which was not really nice to listen to comparing to other diodes. MUR860 is more laid back and a bit slower sounding comparing to MUR1520, and 1520 has a bit more harshness and the same extra detail, which might be appealing to some. I didn't make my choice yet.
But I can stress one thing for sure. The sound of this amplifier is very dependant on rectifier you will use. You can either make an average amp or a great sounding amp (providing other components are wisely chosen as well).
Thanks for trying ! Did you try to parallel two diodes ? (two from the same package)
I am sorry that you were not satisfied by the performance. This means that I'll have to check the MUR's...
Hmmm time to sleep for me (5 am). I have been very addicted to my stereo for the past three days... I really can't part of my setup :-(
Sometimes an inmate laughs when he sees me with my coat on listening to music, trying to leave...
Sound is quite wonderful now after that I fixed a problem in one of my channels. (housings of capacitors shorting to earth and maybe some bad connections). This resulted in *greatly* reduced harshness and improved stereo placement. For the first time I get the real 'Tannoy' feeling I expected after buying my SGM-12X speakers. Smoothness&placement!
BTW: I just listened to a Victor Wooter cd again, this music is so funky
Fedde
Rectifiers, another option
Using individual rectifier diodes is almost accepted as 'standard procedure' these days in audio DIY. With a bewildering choice of diodes with exotic specifications it's understandable.
However, Dejan Veselinovic makes a good case for using a ready-made bridge on his site Zero Distortion
Click on the 'Technology' link and then read his articles on power supplies.
Using individual rectifier diodes is almost accepted as 'standard procedure' these days in audio DIY. With a bewildering choice of diodes with exotic specifications it's understandable.
However, Dejan Veselinovic makes a good case for using a ready-made bridge on his site Zero Distortion
Click on the 'Technology' link and then read his articles on power supplies.
tbla said:regardless of what exotic diodes one chooses to use, there must be a complete snubber circuit arround it..........!
I tried mine with snubbers and all it did was soften the detail. YMMV
I am using the MBR20100 schottkys from OnSemi parralleled up, and I like them,(although I have not tried the MUR devices yet, I have tried most others). Like Fedde stated, they produced an amp that was very hard to stop listening to, you always want to just try another track to see how it sounds
Oh well, here comes another mod to the circuit, will these things ever be finished?!?
tbla said:did you just bypass the diode with 0,1uF or did you design a full snubber....?
Just bypassed, using 0.047, 0.1, 0.47, and 1uf in comparison.
Being an Electronics Ignoramous as I am, could you give details on the full snubber that you are talking about, if I'm going to try new diodes, I might as well give this a go as well!
here is some night reading about snubber circuits......
http://ken-gilbert.com/images/pdf/Calculatin_ Optimum_Snubbers.pdf
http://ken-gilbert.com/images/pdf/Calculatin_ Optimum_Snubbers.pdf
Bricolo said:
Well that all depends on what you do behind the rectifiers. If you think about the function of a rectifier, and what's happening with the rails, the as long as you have enough capacitence and a high enough slew rate and low enough ESR, it shouldn't make a bit of difference.
I'm sure tons of people are going to jump up and scream about how the differences cannot be understood by measurement and that different diodes have inherently different sounds.
I've listened to various diodes, and all else being equal, have never heard any difference that could be reliably reproduced.
Peter Daniel said:
I tried them today. The Future-Active part no. was MBR201100CT, schottky barrier rectifiers,20A 100V.
Not even a match for both MUR860 and MUR1520. While Schottky didn't sound bad, they presented sort of harshness which was not really nice to listen to when comparing to other diodes. MUR860 is more laid back and a bit slower sounding comparing to MUR1520, and 1520 has a bit more harshness and at the same time, an extra detail, which might be appealing to some. I didn't make my choices yet.
But I can stress one thing for sure. The sound of this amplifier is very dependant on rectifier you will use. You can either make an average amp or a great sounding amp (providing other components are wisely chosen as well).
Many years ago, when this fast diodes matter surfaced, Pete Goudreau commented on some tests he made. He used RC snubbers (instead of just C snubbers) bypassing common diodes and got results that were quite similar (in audio improvement) to those obtained with fast diodes.
Why don't you try a regular diode bridge, high amperage, using RC snubbers and see how it compares to the 1520/860 reference?
Carlos
The explanation.
Can anyone explain why the rectifiers in the power supply have such a significant effect.
I thought that the switching process generated RF. This varies with all the different diodes and snubbers etc.
Amplifiers that could somehow pick up these signals either by coupling or by radiation could produce artifacts in the audible range. With random fluctuation in the current amplitude while playing music this probably produces lots of hash that colours the sound. So if this is possible , an amp with very low sensitivity to RF might sound good with any type of supply(?).
Many years ago Hi-Fi News and Record review used to do a sweep of the amplifiers response all the way into the RF region and you might get a shock when you find that many amplifiers HAD sensitivity to RF.
Can anybody suggest a simple test to cHeck this out .
Cheers.
Can anyone explain why the rectifiers in the power supply have such a significant effect.
I thought that the switching process generated RF. This varies with all the different diodes and snubbers etc.
Amplifiers that could somehow pick up these signals either by coupling or by radiation could produce artifacts in the audible range. With random fluctuation in the current amplitude while playing music this probably produces lots of hash that colours the sound. So if this is possible , an amp with very low sensitivity to RF might sound good with any type of supply(?).
Many years ago Hi-Fi News and Record review used to do a sweep of the amplifiers response all the way into the RF region and you might get a shock when you find that many amplifiers HAD sensitivity to RF.
Can anybody suggest a simple test to cHeck this out .
Cheers.
schmad said:
The difference can be understood easily and is easily measured. Just blow up the diode switch off moment for the diode you have and you'll see. All diodes behave differently and show various amounts and characteristics of ringing at switch off. Turn-on characteristics are also different. Your cap bank is designed to smooth to DC at low frequencies but might not work optimally at higher frequencies like those of the ringing frequencies. The high frequency garbage is passed to your circuits possibly causing all sorts of problems like oscillation and what not. Other than that I believe that different turn-on characteristics give different conduction angles as well as noise and thus different problems passed to your circuit.
However, if I or somebody else can hear these differences is as you imply a different issue. That the differences are there and easy to measure should be obvious. The statement that it shouldn't make a bit of difference seems odd as, IMHO, the technical aspects should fairly clearly indicate that there are differences.
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