Hi again. I have an issue with the sound of my latest amp. It has overly strident high frequencies. The amp boards are full of small value film caps which are most likely causing it.
I preferably want a relatively warm, smooth sound, so I was thinking about using Russian oil caps.
The amp in question is an Onkyo M-505. Below is the schematic.
I preferably want a relatively warm, smooth sound, so I was thinking about using Russian oil caps.
The amp in question is an Onkyo M-505. Below is the schematic.
You may not understand the nature of my post. I am looking for your input on how to go about sweetening up the sound of this otherwise competant performer.
I have replaced all of the electrolytics with Elna Silmics. I need to know which of the small value caps are actually needed, and which effect the sound the most?
I have replaced all of the electrolytics with Elna Silmics. I need to know which of the small value caps are actually needed, and which effect the sound the most?
What are you feeding into the amp as the source device? What speakers are you using? What are you doing about ground loops, and EMI/RFI problems? Why do you think cap swapping is going to fix it?
I have a complete system profile posted here, accept for a Sony ES receiver which currently sounds better than my PS Audio when used as a preamp.
I replaced the caps on the amp boards because the old ones were leaking.
I replaced the caps on the amp boards because the old ones were leaking.
It may not have been used much for quite some time.
Use it regularly for a few weeks, and see if it doesn't get better. It should.
This is common with seldom used amps, even new ones.
And the new caps have been on the shelf for a long time as well.
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They are mainly compensation or stability caps, removing them is a very bad idea as you could turn the amp into an oscillator. They don't affect the sound, this is a linear amp with feedback, you are hearing what went in, basically. That's set by the feedback network which is two resistors.
What I am hearing is the equivalent of the way bad digital effects the high frequencies. This is from a most competant vinyl front end as attested to by my transparent headphone rig.
This amp is distorting the sound.
This amp is distorting the sound.
It could be distortion, or it could be a type of noise problem. I take it you mean the HF is grainy and or veiled sounding, something like that?
There are a few factors affecting HF distortion. The others are PCB layout and transistor matching. There are some others.
Messing around like this may not end well. Replacing the leaky capacitors was required, but you won't hear a difference between good coupling capacitors (which you found out).
Messing around like this may not end well. Replacing the leaky capacitors was required, but you won't hear a difference between good coupling capacitors (which you found out).
Grossly so, or more like a not very nice dac?
Aside from the above question, I think rayma's suggestion to give it maybe a couple of weeks of runtime would be a conservative thing to try. Then if its still unpleasant for you to listen to, probably it should be looked at by a competent technician. Seems a little odd that both channels would be equally affected though.
Also, although I am not expert on the subject, IIUC there was a period in the history of some Japanese amplifiers whereby they had good standard measurements at the time but the sound wasn't so good. Don't know if the amp you have might fall into that category.
In addition, its possible for an audio device to sound distorted to a human, but not exactly distorted in terms of the way engineers typically measure. In that case the problem may be what might be termed a signal-correlated noise. A sort of statistical distortion that doesn't look like a normal distortion in some tests. A bad, loose, and or corroded ground might be involved in such a case, or maybe something else. Probably wouldn't hurt to take a close look at any ground connections and verify they are still tight and secure. Then give it some time and see it it gets better.
Aside from the above question, I think rayma's suggestion to give it maybe a couple of weeks of runtime would be a conservative thing to try. Then if its still unpleasant for you to listen to, probably it should be looked at by a competent technician. Seems a little odd that both channels would be equally affected though.
Also, although I am not expert on the subject, IIUC there was a period in the history of some Japanese amplifiers whereby they had good standard measurements at the time but the sound wasn't so good. Don't know if the amp you have might fall into that category.
In addition, its possible for an audio device to sound distorted to a human, but not exactly distorted in terms of the way engineers typically measure. In that case the problem may be what might be termed a signal-correlated noise. A sort of statistical distortion that doesn't look like a normal distortion in some tests. A bad, loose, and or corroded ground might be involved in such a case, or maybe something else. Probably wouldn't hurt to take a close look at any ground connections and verify they are still tight and secure. Then give it some time and see it it gets better.
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Everything is tight in it, no corrosion to speak of. The amp will be running brown ambient noise 24/7 if it doesn't burn up any more caps. I will take another listen to it in 2 weeks time.
Meanwhile, I need to find another amp as my receiver is failing to output sound.
Meanwhile, I need to find another amp as my receiver is failing to output sound.
One issue was that back then we could only see -80 dB below 1 watt. Distortion products wouldn't look like much, but today they stand out like a sore thumb. Times ... they have changed.
Hi TheSoundMann,
Caps don't burn in. The signal you send doesn't matter either. You become used to the sound, that is what is happening.
Caps don't burn in. The signal you send doesn't matter either. You become used to the sound, that is what is happening.