Sbiswas1,
Replying in principle, did not look up the Leach amp.
The two windings supply half of the total power each, voltage wise. The top half supplies +V and the bottom half -V. Thus the total voltage is 2V as their outputs are connected in series.
The same current flows through both the supplies (assuming that the amplifier demand is basically the same from +V and -V). If that was 12A, then both windings need to be able to supply 12A nominal, as do both rectifier packs. The 'saving' lies in the rectifier voltage rating, which (theoretically) needs to be Vp each. One rectifier bridge pack could have been used with the two windings in series, center tap at their junction, if the rectifier voltage rating was doubled. (I fear I cannot quite see the advantage claimed by the circuit designer; rectifier bridge packs with a high enough voltage rating are easily available. Not to be unduly critical, but with the shown design one has 4 series diodes in the line at any stage while with one bridge there are only two - for whatever small advantage that might be. But that was not part of your question.)
Replying in principle, did not look up the Leach amp.
The two windings supply half of the total power each, voltage wise. The top half supplies +V and the bottom half -V. Thus the total voltage is 2V as their outputs are connected in series.
The same current flows through both the supplies (assuming that the amplifier demand is basically the same from +V and -V). If that was 12A, then both windings need to be able to supply 12A nominal, as do both rectifier packs. The 'saving' lies in the rectifier voltage rating, which (theoretically) needs to be Vp each. One rectifier bridge pack could have been used with the two windings in series, center tap at their junction, if the rectifier voltage rating was doubled. (I fear I cannot quite see the advantage claimed by the circuit designer; rectifier bridge packs with a high enough voltage rating are easily available. Not to be unduly critical, but with the shown design one has 4 series diodes in the line at any stage while with one bridge there are only two - for whatever small advantage that might be. But that was not part of your question.)
Sbiswas1 (follow):
I am sitting here with a frown on my face, except for being quite off topic by now; apology. I have simply tried to answer your question, but ....
I scrutinized the reference's text. The writer claims that the figure 4 shows an improvement as there are now two seperate rectifiers, making each channel independent of the other.... Are we looking at the same diagram or using the same terminology?
I see a single channel supply with a +V and -V split power supply, as for most amplifiers with a "+" section and a "-" one, power supply wise. (I presume "channel" refers to either the left or right hand amplifiers as in stereo, not two 'sides' of the same channel power supply.)
It is 01:00 a.m. here when most folks are sleeping, I have not had any of the 'fruit of the vine' benefits, but somewhere I seem to have gone off the track. Waiting to be re-shunted ....
I am sitting here with a frown on my face, except for being quite off topic by now; apology. I have simply tried to answer your question, but ....
I scrutinized the reference's text. The writer claims that the figure 4 shows an improvement as there are now two seperate rectifiers, making each channel independent of the other.... Are we looking at the same diagram or using the same terminology?
I see a single channel supply with a +V and -V split power supply, as for most amplifiers with a "+" section and a "-" one, power supply wise. (I presume "channel" refers to either the left or right hand amplifiers as in stereo, not two 'sides' of the same channel power supply.)
It is 01:00 a.m. here when most folks are sleeping, I have not had any of the 'fruit of the vine' benefits, but somewhere I seem to have gone off the track. Waiting to be re-shunted ....
John,
I am in India .. so there is a day lite difference.
The Leach double barrel amplifier runs at +/- 85Volt to 93 Volt DC @ 12 Ampere. So was thinking is there any benefit of using 2 Bridge rectifier (KBPC06-35) on each half of the secondary winding of the transformer. Or its better to use single bridge rectifier in series,center tap at their junction.
Thinking of using a transformer with two bridge rectifier in series with 2 X 0-65 Volt with each secondary winding at 12 Ampere each. By connecting the secondary winding in series, will the output Voltage will be +/- 90 to 93 Volt at 12 Ampere ?
I am planning to use two separate transformer for each Right and left channel of the amplifier.
I am in India .. so there is a day lite difference.
The Leach double barrel amplifier runs at +/- 85Volt to 93 Volt DC @ 12 Ampere. So was thinking is there any benefit of using 2 Bridge rectifier (KBPC06-35) on each half of the secondary winding of the transformer. Or its better to use single bridge rectifier in series,center tap at their junction.
Thinking of using a transformer with two bridge rectifier in series with 2 X 0-65 Volt with each secondary winding at 12 Ampere each. By connecting the secondary winding in series, will the output Voltage will be +/- 90 to 93 Volt at 12 Ampere ?
I am planning to use two separate transformer for each Right and left channel of the amplifier.
I believe that the dual bridge rectifier only offers an advantage over the single bridge rectifier when building a two (or more) channel amplifier.
In a monoblock assembly I cannot measure any difference in performance between dual and single, except that the dual rectifier has a slightly lower supply voltage and thus a slightly lower peak output on transients (and on measured maximum power output).
In a monoblock assembly I cannot measure any difference in performance between dual and single, except that the dual rectifier has a slightly lower supply voltage and thus a slightly lower peak output on transients (and on measured maximum power output).
Hi Andrew, this post from Nelson gives another reason http://www.diyaudio.com/forums/pass...l-alephx-high-power-version-7.html#post289095
Tony.
Tony.
Reasons 1 & 2 don't apply to our comparison of dual vs single bridge rectifier.
Reason 3 applies if there is a difference in current draw from the two polarities. As N.Pass states this can happen if there is significant DC or output offset current.
I hope your protection systems shut down your amplifier before that significant output current offset damages your speaker/s.
I.E. I don't accept that as a valid reason for a normally operating amplifier on audio/music signals.
Reason 3 applies if there is a difference in current draw from the two polarities. As N.Pass states this can happen if there is significant DC or output offset current.
I hope your protection systems shut down your amplifier before that significant output current offset damages your speaker/s.
I.E. I don't accept that as a valid reason for a normally operating amplifier on audio/music signals.
Hi Andrew,
You said you couldn't see any other reason. So I thought I would point this out, as I remembered it. Basically as I interpret it, if you have mismatched secondaries on your transformer, then under heavy current draw you can end up with a saturation that causes mechanical hum. Using dual bridges apparently makes it a non issue. So I would call that a valid reason to use dual rectifiers 🙂
Tony.
You said you couldn't see any other reason. So I thought I would point this out, as I remembered it. Basically as I interpret it, if you have mismatched secondaries on your transformer, then under heavy current draw you can end up with a saturation that causes mechanical hum. Using dual bridges apparently makes it a non issue. So I would call that a valid reason to use dual rectifiers 🙂
Tony.
Most and maybe all dual secondary transformers are bi-fillar wound. This ensures that the number of secondary turns is exactly matched. It is very easy to check that the same number of turns have been wound on the dual secondary (and centre tapped) transformer.
I don't accept your interpretation of what N.Pass is referring to.
I don't accept your interpretation of what N.Pass is referring to.
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Hi Andrew, your prerogative, but perhaps this post (and Eva's after it) may change your mind 🙂 http://www.diyaudio.com/forums/solid-state/52254-one-two-bridge-ps.html#post583684
This was actually the post I had originally seen.
Tony.
This was actually the post I had originally seen.
Tony.
This is equivalent to 800mVdc of output offset.
I still don't think it applies to our comparison.
Would a similar "saturation buzz" occur if the output offset current were <=10mA?
or <=1mA?
Would normal small output offsets cause sufficient unbalance of secondary winding currents to then upset the PSU output voltages? Would than then ripple through to affect the sound quality of the amplifier/speaker?
I don't think so.
If I were to hear my transformer suffering symptoms of saturation, then I would investigate and correct the problem. One of the solutions would be the dual secondary and dual rectifier, as well as others.
That to me does not equate to an unqualified "dual rectifiers offer a better solution than single rectifiers".
Hi Guys
We have the "Hifi Design Downloads" section on our site now. There are a few different power amps, with more to come, and a couple of crossovers, so far. The NO-CLIP will be up shortly.
The amp for this thread is listed as LTT4.
Regarding the use of single overall bridge or individual bridges for PT secondaries:
There is no performance difference. Period.
The usual reasons for using dual bridges are simply related to ease of assembly and eliminating the need to "phase" the secondaries. Modern off-the-shelf toroidal PTs have two secondaries. There is a standard colour code that most manufacturers follow for these, but... there are some builders who do not. In any case, the windings must effectively be placed in series for the split rail app, and the junction of the windings used as the CT.
You can pick any two secondary leads and tie them together. The voltage across the free wires will either be close to zero or twice the individual winding voltage. If it is the latter, the winding is correctly phased and you can use the free ends to tie to the bridge. If you saw a zero reading, swap one of the joined wires for the other end of that winding and verify the new connection.
When phasing the PT, it is best to connect it to the mains through a low-wattage light bulb.
Obviously, as long as you know which pair of wires belong to each winding, using separate bridges is straight forward. I would not worry about the loss through two diodes versus one, as the "headroom" is insignificant. If you are pushing the amp that hard, maybe you need to reassess the circuit or your use of the equipment....
For this amp, a standard 25-35A bridge is ample. Bolt it to the chassis. The GBC-style has leads that will fit into a PCB.
As far as using separate bridges for each channel:
This has an advantage in keeping parts cost low when very high-currents for supporting stereo would exceed the capability of a single bridge. The PSU notes that are part of LTT4-COMPLETE illustrate single and dual supplies from one PT, along with info for selecting cap sizes.
There is also a slight advantage for channel separation. Note that separate ground links must be provided as discussed in the notes mentioned above.
Johan, your posts are always well written and well thought out.
Have fun
Kevin O'Connor
We have the "Hifi Design Downloads" section on our site now. There are a few different power amps, with more to come, and a couple of crossovers, so far. The NO-CLIP will be up shortly.
The amp for this thread is listed as LTT4.
Regarding the use of single overall bridge or individual bridges for PT secondaries:
There is no performance difference. Period.
The usual reasons for using dual bridges are simply related to ease of assembly and eliminating the need to "phase" the secondaries. Modern off-the-shelf toroidal PTs have two secondaries. There is a standard colour code that most manufacturers follow for these, but... there are some builders who do not. In any case, the windings must effectively be placed in series for the split rail app, and the junction of the windings used as the CT.
You can pick any two secondary leads and tie them together. The voltage across the free wires will either be close to zero or twice the individual winding voltage. If it is the latter, the winding is correctly phased and you can use the free ends to tie to the bridge. If you saw a zero reading, swap one of the joined wires for the other end of that winding and verify the new connection.
When phasing the PT, it is best to connect it to the mains through a low-wattage light bulb.
Obviously, as long as you know which pair of wires belong to each winding, using separate bridges is straight forward. I would not worry about the loss through two diodes versus one, as the "headroom" is insignificant. If you are pushing the amp that hard, maybe you need to reassess the circuit or your use of the equipment....
For this amp, a standard 25-35A bridge is ample. Bolt it to the chassis. The GBC-style has leads that will fit into a PCB.
As far as using separate bridges for each channel:
This has an advantage in keeping parts cost low when very high-currents for supporting stereo would exceed the capability of a single bridge. The PSU notes that are part of LTT4-COMPLETE illustrate single and dual supplies from one PT, along with info for selecting cap sizes.
There is also a slight advantage for channel separation. Note that separate ground links must be provided as discussed in the notes mentioned above.
Johan, your posts are always well written and well thought out.
Have fun
Kevin O'Connor
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Kevin,
Thanks for sharing this design, but unfortunately the link seems to be broken. When I tried to download the LTT4 Free package, the site reported the error "Your URL has Changed!".
Thanks for sharing this design, but unfortunately the link seems to be broken. When I tried to download the LTT4 Free package, the site reported the error "Your URL has Changed!".
Hi Struth
I downloaded the LTT4 package earlier and finished reading the notes, which makes for remarkably interesting and informative reading. I'm tempted to send the Gerbers off to a board house and try this design out for myself...
Thanks again for this contribution.
Regards
I downloaded the LTT4 package earlier and finished reading the notes, which makes for remarkably interesting and informative reading. I'm tempted to send the Gerbers off to a board house and try this design out for myself...
Thanks again for this contribution.
Regards
Might be worth a group buy. If you come up with a price and a few extra helps the price PM me.
Hey guys, have anyone proceeded to build this amp? It's almost one month now & no news? Come on lets see some pictures of those boards! 😀
Hey!
I'm currently raising money as i had to use my economies for something else. Anyway, i will build it sometime this year.
Also, i was thinking of an arduino protection. Arduino Uno is something like 20 euros and the auxiliary circuits for detection are not expensive at all so i could get away with Soft start, short circuit protection, power on mute, dc protection, over temperature protection and AC monitoring for something less than 40 euros. This only if the arduino platform can support this kind of multi tasking. I posted over at forums.arduino.cc and i am currently waiting an answer as if it is possible to implement something like this, software wise.
If you have anything to say about this, please, by all mean, pm me or even better, post here so more of us diyers can see.
Here's the post regarding my problem over at arduino.cc forums.
I'm currently raising money as i had to use my economies for something else. Anyway, i will build it sometime this year.
Also, i was thinking of an arduino protection. Arduino Uno is something like 20 euros and the auxiliary circuits for detection are not expensive at all so i could get away with Soft start, short circuit protection, power on mute, dc protection, over temperature protection and AC monitoring for something less than 40 euros. This only if the arduino platform can support this kind of multi tasking. I posted over at forums.arduino.cc and i am currently waiting an answer as if it is possible to implement something like this, software wise.
If you have anything to say about this, please, by all mean, pm me or even better, post here so more of us diyers can see.
Here's the post regarding my problem over at arduino.cc forums.
I'm interested in this too.
I have a couple of arduinos, one uno and one nano. I could try some testing eventually...
brlmat
There is some merit in Arduino Uno but there are other ways as I have done using a xmega MCU and some BASCOM-AVR code. xmega I suggest should be used for new designs for many reasons.
Most important to run your MCU and its peripherals at 3.3V logic. +5V MCU's have been dead for many years because the standard these days is 3.3 & 2.5V logic. The HV stuff is done by relays, FETs.
I first started with a sparkfun xmega128A breakout board and put that of a 100 mil protoboard. Even used old style wire wrap posts, real easy. I'd share that code with you. It uses a 4x40 LCD and Bourns rotary encoders with switch/led. Nothing overly complicated.
Your design consists of a basic MCU and it associated interfaces, which BTW encompass more circuitry than the MCU section does.
I would review your design if you post it.
Rick
There is some merit in Arduino Uno but there are other ways as I have done using a xmega MCU and some BASCOM-AVR code. xmega I suggest should be used for new designs for many reasons.
Most important to run your MCU and its peripherals at 3.3V logic. +5V MCU's have been dead for many years because the standard these days is 3.3 & 2.5V logic. The HV stuff is done by relays, FETs.
I first started with a sparkfun xmega128A breakout board and put that of a 100 mil protoboard. Even used old style wire wrap posts, real easy. I'd share that code with you. It uses a 4x40 LCD and Bourns rotary encoders with switch/led. Nothing overly complicated.
Your design consists of a basic MCU and it associated interfaces, which BTW encompass more circuitry than the MCU section does.
I would review your design if you post it.
Rick
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Hey everyone.
Thanks rsavas, but i'll be using analog detection. I will share my schematic once it's done. I got to the conclusion that a mcu doesn't replace much.
Although i would be extremely to find a schematic which either sends a pulse or a continuous voltage 1 sec from power on and one that either send one pulse or a continuous voltage after 5 sec from power on.
The thing is that i have the 1 sec softstart which i wouldn't do with a RC timer as it doesn't always get discharged fast enough in case of power cycling. I also need the 5 sec timer for power on mute which again, would only work properly with something other than a RC timer. I thought of using a 555 timer but i have yet to unravel the ways it can be set up.
Thanks rsavas, but i'll be using analog detection. I will share my schematic once it's done. I got to the conclusion that a mcu doesn't replace much.
Although i would be extremely to find a schematic which either sends a pulse or a continuous voltage 1 sec from power on and one that either send one pulse or a continuous voltage after 5 sec from power on.
The thing is that i have the 1 sec softstart which i wouldn't do with a RC timer as it doesn't always get discharged fast enough in case of power cycling. I also need the 5 sec timer for power on mute which again, would only work properly with something other than a RC timer. I thought of using a 555 timer but i have yet to unravel the ways it can be set up.
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