Fast answer, so you don't have to read all the thread:
The electrolityc caps that are on the input board, were bad, and they use to leak its "juice"
all over the PCB, which is very very difficult to thoroughly remove, I do not have a ultrasonic cleaner, i washed the PCB several times with dishsoap and a toothbruch several times, with the close components to the caps removed.
regards
Alex
The electrolityc caps that are on the input board, were bad, and they use to leak its "juice"
all over the PCB, which is very very difficult to thoroughly remove, I do not have a ultrasonic cleaner, i washed the PCB several times with dishsoap and a toothbruch several times, with the close components to the caps removed.
regards
Alex
Hi a.wayne,
Never work on electronic equipment unless you know exactly what you are doing. Sadly, many people working as technicians have little idea how a simple amplifier works. Often some of them do not posses the soldering skills to work on anything.
Hi Gary,
Adcom amplifiers have supply decoupling caps on the boards. Audiophile caps will only reduce the number of CDs or records you can afford to buy. Probably about as effective as a brick sitting on top, or speaker cable lifts. The recommended fuses have the proper fail time as designed. You should not deviate from that.
-Chris
I imagine that using the wrong cleaning solution could certainly damage the boards and /or the components on those boards. I have never had a damaged board and I remove sensitive components before cleaning.
That's pretty good. What's the problem?
Probably would be too much load. Never mind the other issues involved. What ever would you be trying to accomplish by doing this?
Never work on electronic equipment unless you know exactly what you are doing. Sadly, many people working as technicians have little idea how a simple amplifier works. Often some of them do not posses the soldering skills to work on anything.
Hi Gary,
Adcom amplifiers have supply decoupling caps on the boards. Audiophile caps will only reduce the number of CDs or records you can afford to buy. Probably about as effective as a brick sitting on top, or speaker cable lifts. The recommended fuses have the proper fail time as designed. You should not deviate from that.
-Chris
Hi mjraudio,
Man, how to say this.
I had a look at your web site and was not pleased to find what you are up to. You are advocating so much audio myth and drivel that I found myself a little upset as to what you are promoting. You must remember that you are spending other people's money here. Someone who does not know that much will look at anyone with more knowledge as someone to guide them. You are misguiding, not helping.
Look, if you want to experiment with tweaks on your own stuff, then fine. Go for it. Until you have the equipment and knowledge to be able to prove some of your concepts, then you are selling snake oil.
Basically, you are not fully trained. You do not have the experience that will temper you youthful zeal and it is your customers who will pay for your lack of experience. You are playing the same game that Mike Elliott of Counterpoint plays.
I'm very sorry to have had to say this, but you are advertising out in the open on your web site. I feel that you need a public reply in that case. Since you learned most of your servicing points here, the least you could do is to provide an honest and responsible service.
You have jumped on the one nerve that gets me angry.
-Chris
Man, how to say this.
I had a look at your web site and was not pleased to find what you are up to. You are advocating so much audio myth and drivel that I found myself a little upset as to what you are promoting. You must remember that you are spending other people's money here. Someone who does not know that much will look at anyone with more knowledge as someone to guide them. You are misguiding, not helping.
Look, if you want to experiment with tweaks on your own stuff, then fine. Go for it. Until you have the equipment and knowledge to be able to prove some of your concepts, then you are selling snake oil.
Basically, you are not fully trained. You do not have the experience that will temper you youthful zeal and it is your customers who will pay for your lack of experience. You are playing the same game that Mike Elliott of Counterpoint plays.
I'm very sorry to have had to say this, but you are advertising out in the open on your web site. I feel that you need a public reply in that case. Since you learned most of your servicing points here, the least you could do is to provide an honest and responsible service.
You have jumped on the one nerve that gets me angry.
-Chris
Hi a.wayne,
How exactly do you think doubling the supply capacitance is going to help since there is already enough capacitance in the supplies? On top of that, each channel has it's own filter caps and rectifiers. In fact, the only time extra capacitance can possibly help you is at or near clipping. Most people don't listen to music that way.
Now, think of the noise that may be generated by rectifiers. Doubling the capacitance may reduce the conduction angle. This will increase the generation of noise due to higher amplitude current pulses. This also increases the IR losses everywhere, including your power transformer. If the conduction angle does not increase, then the extra capacitance is having no effect at all.
There is only one time that increasing the supply capacitance is helpful. That is where the original design specified filter capacitors that were far to small. More is certainly not better in normal situations.
-Chris
Yes, that is exactly what I am saying. You are actually causing more noise and a warmer running transformer. That's assuming the soft start survives.
How exactly do you think doubling the supply capacitance is going to help since there is already enough capacitance in the supplies? On top of that, each channel has it's own filter caps and rectifiers. In fact, the only time extra capacitance can possibly help you is at or near clipping. Most people don't listen to music that way.
Now, think of the noise that may be generated by rectifiers. Doubling the capacitance may reduce the conduction angle. This will increase the generation of noise due to higher amplitude current pulses. This also increases the IR losses everywhere, including your power transformer. If the conduction angle does not increase, then the extra capacitance is having no effect at all.
There is only one time that increasing the supply capacitance is helpful. That is where the original design specified filter capacitors that were far to small. More is certainly not better in normal situations.
-Chris
Hello Chris,
i would agree if you are using an amplifier with small driver and output stage and operating @ 8 ohm. On an amplifier with 20 output devices/ch and operating at 1 ohm 75, 000 uf is not enuff !
In such circumstances 150,000 per side is ball park adequate and yes this does make a big difference both on the bench and in listening ...
A.Wayne
i would agree if you are using an amplifier with small driver and output stage and operating @ 8 ohm. On an amplifier with 20 output devices/ch and operating at 1 ohm 75, 000 uf is not enuff !
In such circumstances 150,000 per side is ball park adequate and yes this does make a big difference both on the bench and in listening ...
A.Wayne
Gentlemen ,
I do believe the issue at hand , is how much is enough ?
Megajocke, agree, measuring the ripple at the respective load would put this into perspective as to what is enough.............
To say 75,,000 is enough irrespective of taking into consideration the required usage i do not agree with...agree that the added capacitance will affect transformer conduction angle, conduction angle always changes with DC load . It is my opinion that it is better to have good DC regulation , even if this means a higher Conduction angle in the transformer , unless of course we exceed the head room on the T.T. There is no something for nothing.
I do believe the issue at hand , is how much is enough ?
Megajocke, agree, measuring the ripple at the respective load would put this into perspective as to what is enough.............
To say 75,,000 is enough irrespective of taking into consideration the required usage i do not agree with...agree that the added capacitance will affect transformer conduction angle, conduction angle always changes with DC load . It is my opinion that it is better to have good DC regulation , even if this means a higher Conduction angle in the transformer , unless of course we exceed the head room on the T.T. There is no something for nothing.
Hi Joe,
Hi a.wayne,
Look at Carver amps (and others). They deliver silly amounts of power with small filter capacitors. They are also rated for 4 ohm loads and bridging. So much for the low impedance load argument as a brick wall problem.
What I think you are experiencing is either psychoacoustic in nature, or really bad AC power supply issues. A well designed amplifier will have regulated voltage amp stages. This insulates them from any antics in the DC rail voltages. If you look at something like a Marantz 300DC (a very good design), you will see that the voltage amplifier sections are not only running off a regulated supply each, but they are also on their own private windings. Life is beautiful in that amp. If your supplies are bouncing up and down, and this does affect the voltage amp stages, the amplifier is not a good match for you. Adding capacitance is but a bandaid solution and does not address the real problems. If you consider the design goal of the Adcom line, some things become clear. These were designed as affordable amplifiers for their price range!!! That last line is pretty important you know. They are very good amplifiers but were never intended to be the best amplifiers. They never pretended to fill that role. I like them, but I do not use these in any of my systems. So, being super critical of their performance tells me that you have the wrong amplifiers. Spend more money. If you wish to improve their performance, you will have to dig deeper and fix little things, those filter caps are not the cause of what you are hearing. You want more PSRR in the voltage amp stage - simple. By adding larger capacitors, you are increasing the strength of the current pulses that do bleed into other supplies via the power transformer windings. You should be reducing these current pulses. As the duty cycle of the pulses is reduced, higher frequencies are produced. These higher frequencies couple much more easily into other areas of the amplifier. The benign ripple you are talking about is not even close to a problem. Well, not unless you are complaining about the hum in the speaker that possibly might be audible on a clipped waveform.
One last point. Until you get close to clipping, supply ripple (within reason) will not affect the reproduction of any bass frequency. Your feedback is greatest at low frequencies. Therefore, error correction is greatest at low frequencies. So to take this to an extreme I'll give you the following example. Assume the amplifier has no inherent weaknesses and supply PSRR is normal for amplifiers of this power. Assume a rail voltage of 80 VDC and a ridiculous ripple voltage of 10 V peak to peak. Your output waveform is 80 V peak to peak. That's pretty loud, right? You will still have 30 V peak on each rail in excess of the demands. Feedback will guarantee a low distortion output at any frequency within the passband that excludes supply ripple. You can not measure, nor can you hear any effects from those bad capacitors. I know this from both measurements and many years of seeing amplifiers come in and customer complaints. So, although it's nice to think you can hear these things, long experience tells me that you can't. Not unless someone tells you that the amp has bad caps.
-Chris
No, I wouldn't say that. The limit to output power will always be how much you can drag out of your AC mains. That's assuming the amplifier circuit is designed properly to begin with. Power begins with rail voltages and ends with current delivery. This has about zero to do with supply ripple - unless you are running into clipping. Even then, delivered power differences between "monster cap amp" and "blissfully stocko amp" would be very small.
Hi a.wayne,
Look at Carver amps (and others). They deliver silly amounts of power with small filter capacitors. They are also rated for 4 ohm loads and bridging. So much for the low impedance load argument as a brick wall problem.
What I think you are experiencing is either psychoacoustic in nature, or really bad AC power supply issues. A well designed amplifier will have regulated voltage amp stages. This insulates them from any antics in the DC rail voltages. If you look at something like a Marantz 300DC (a very good design), you will see that the voltage amplifier sections are not only running off a regulated supply each, but they are also on their own private windings. Life is beautiful in that amp. If your supplies are bouncing up and down, and this does affect the voltage amp stages, the amplifier is not a good match for you. Adding capacitance is but a bandaid solution and does not address the real problems. If you consider the design goal of the Adcom line, some things become clear. These were designed as affordable amplifiers for their price range!!! That last line is pretty important you know. They are very good amplifiers but were never intended to be the best amplifiers. They never pretended to fill that role. I like them, but I do not use these in any of my systems. So, being super critical of their performance tells me that you have the wrong amplifiers. Spend more money. If you wish to improve their performance, you will have to dig deeper and fix little things, those filter caps are not the cause of what you are hearing. You want more PSRR in the voltage amp stage - simple. By adding larger capacitors, you are increasing the strength of the current pulses that do bleed into other supplies via the power transformer windings. You should be reducing these current pulses. As the duty cycle of the pulses is reduced, higher frequencies are produced. These higher frequencies couple much more easily into other areas of the amplifier. The benign ripple you are talking about is not even close to a problem. Well, not unless you are complaining about the hum in the speaker that possibly might be audible on a clipped waveform.
One last point. Until you get close to clipping, supply ripple (within reason) will not affect the reproduction of any bass frequency. Your feedback is greatest at low frequencies. Therefore, error correction is greatest at low frequencies. So to take this to an extreme I'll give you the following example. Assume the amplifier has no inherent weaknesses and supply PSRR is normal for amplifiers of this power. Assume a rail voltage of 80 VDC and a ridiculous ripple voltage of 10 V peak to peak. Your output waveform is 80 V peak to peak. That's pretty loud, right? You will still have 30 V peak on each rail in excess of the demands. Feedback will guarantee a low distortion output at any frequency within the passband that excludes supply ripple. You can not measure, nor can you hear any effects from those bad capacitors. I know this from both measurements and many years of seeing amplifiers come in and customer complaints. So, although it's nice to think you can hear these things, long experience tells me that you can't. Not unless someone tells you that the amp has bad caps.
-Chris
Hi megajocke,
The one thing I have not studied is how extra capacitance works in class A amplifiers. Nelson Pass has seen that higher capacitance helps in these cases. Keep in mind that we are talking about much larger ripple currents with class A amplifiers. I'll accept his findings, but that does not mean this applies directly to class AB amplifiers.
-Chris
If that is true, then the added capacitance isn't doing much. Overall, the change in conduction angle will not change much. However, when that charge period becomes that small, a little less charge time can cause the current spike to grow larger than one might think. It is this current pulse that increases a lot and is the main concern. This current pulse will also tend to cause "ringing" in components and wire, this increases as the current increases.
Possibly, but you still couldn't hear it unless the amplifier was not well designed. In no way would the bass "sound more solid" or any other silly phrase the audio press comes up with. You will often see this as a marketing device used in ads or the specialty repair shops. Right along side "silver wire", "oxygen free" copper wire or teflon insulated wires. Do you know some people can hear the difference between wire when it is a single solid conductor passing through the air, clear of all objects? I'd have to say that the bulk of the dielectric is ..... air.
The one thing I have not studied is how extra capacitance works in class A amplifiers. Nelson Pass has seen that higher capacitance helps in these cases. Keep in mind that we are talking about much larger ripple currents with class A amplifiers. I'll accept his findings, but that does not mean this applies directly to class AB amplifiers.
-Chris
the only measreable effect that playing with filter cap capacitance would really have is it's contribution to output impedance. at 60hz the typical 15,000uf cap has an Xc of about 175 milliohms, and a 75000uf cap 35 milliohms. since to the output these capacitances are essentially in parallel, the 15000uf power supply would have an Xc of 87.5 milliohms and the 75000uf power supply has an Xc of 17.5 millohms. so essentially we have power supply rails with (not taking any fudge factors into account) impedances of 87.5 milliohms and 17.5 milliohms. add the physical output resistance of the amp, let's say 100 milliohm. this alreasy reduces the effects of the caps. then factor in the feedback ratio of a typical amp, and the actual difference of the effects between the two power supplies would be measured in microohms.
Chris,
Appreciate the input and If running @ 8 ohms , agree somewhat . operate that same amplifier @ 2 /1 ohm impedances and the difference is very audible. Try switching out your 8 Ohm dummy load for a 2 ...and measure again .
Again the question is how much ? what is the magical number that is good ? what amplifier would you consider to be an "improvement" over modifying these monoblocs. Again @ 2 ohms and below i have just about eliminated 95 % of the amplifiers available. You would be amazed at how many " top notch " amps run off and cry when faced with this. I do agree about the sound of the adcom , but in my current low impedance setup they sing with the best of them...
regards,
Appreciate the input and If running @ 8 ohms , agree somewhat . operate that same amplifier @ 2 /1 ohm impedances and the difference is very audible. Try switching out your 8 Ohm dummy load for a 2 ...and measure again .
Again the question is how much ? what is the magical number that is good ? what amplifier would you consider to be an "improvement" over modifying these monoblocs. Again @ 2 ohms and below i have just about eliminated 95 % of the amplifiers available. You would be amazed at how many " top notch " amps run off and cry when faced with this. I do agree about the sound of the adcom , but in my current low impedance setup they sing with the best of them...
regards,
Oh, with "measurable" I meant that the RMS current draw and transformer losses would be measurably different, not that the amp would measure or sound different except a small increase in output power and better clipping behaviour with bigger caps. But 20% ripple would probably be classed as "too small" caps by most people.
A bigger problem than change in conduction angle is probably the startup surge though... If the caps and transformer are very large the rectifier is in great danger if there is no soft start.
A bigger problem than change in conduction angle is probably the startup surge though... If the caps and transformer are very large the rectifier is in great danger if there is no soft start.
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