Hi,
It's been a while since I visited the site, as I haven't been DIYing lately, but now I need some advice.
Just this weekend I finished recapping an old Marantz SR1000, it had a decent sound, although it was never a showstopper. It had always been a good receiver (I use it on my pc), until a lot of the caps in the power circuit decided to blow up simultaneously. I bought exact equivalents for all except the reservoir caps, which I bought 50% bigger. Also recapped the amplifying circuit, with same value caps all around. Basically replaced old Elnas with brand new ones. It was a bit messy due to all the cabling to the two boards, lack of room etc. But got it done and it all works fine ..........
except that the highs are now noticeably harsh. Which was not the case before, although it was never on the sweet side.
I'm hoping it's just a "burn-in" issue, and am trying to give it some hours playing.
So, I have two questions:
1.- Would recapping have this effect in the overall sound of the receiver ??
2.- Is there any way to fix this, make it sound less harsh and more refined and sweet, even precise for that matter. If I were to describe the sound in terms of images, it sounds as when you set a picture in extreme sharpness, it goes wrong and feels unnatural.
Thanks,
Manolo
It's been a while since I visited the site, as I haven't been DIYing lately, but now I need some advice.
Just this weekend I finished recapping an old Marantz SR1000, it had a decent sound, although it was never a showstopper. It had always been a good receiver (I use it on my pc), until a lot of the caps in the power circuit decided to blow up simultaneously. I bought exact equivalents for all except the reservoir caps, which I bought 50% bigger. Also recapped the amplifying circuit, with same value caps all around. Basically replaced old Elnas with brand new ones. It was a bit messy due to all the cabling to the two boards, lack of room etc. But got it done and it all works fine ..........
except that the highs are now noticeably harsh. Which was not the case before, although it was never on the sweet side.
I'm hoping it's just a "burn-in" issue, and am trying to give it some hours playing.
So, I have two questions:
1.- Would recapping have this effect in the overall sound of the receiver ??
2.- Is there any way to fix this, make it sound less harsh and more refined and sweet, even precise for that matter. If I were to describe the sound in terms of images, it sounds as when you set a picture in extreme sharpness, it goes wrong and feels unnatural.
Thanks,
Manolo
Did you place any additional bypass capacitors? I.e. On the psu main filter capacitors?
Did you adjust the bias, if it is adjustable. Too high of bias can have a brighter sound.
Also it's likely you are hearing more of it's original sound. Aged caps often go lower in value and if so in caps in critical areas like coupling in the amp section on it's input then they can be very noticeable
Did you adjust the bias, if it is adjustable. Too high of bias can have a brighter sound.
Also it's likely you are hearing more of it's original sound. Aged caps often go lower in value and if so in caps in critical areas like coupling in the amp section on it's input then they can be very noticeable
Recently manufactured electrolytic capacitors are of much worse audio quality than those of the past.
I've been using Elna Silmic II caps regularly and I wouldn't describe them as harsh. However, they will certainly require running in, during which the sound may change quite considerably, eventually settling with improved extension in both bass and treble.
I agree vintage caps were much better yet mostly now not at their best and modern replacement can improve sound. Will they be at their best for as long as vintage caps did? No chance.
Good point. They definitely need time to settle, more than any other new caps IME. Although they sound really smooth after a while
I have another problem now right channel is crackling, and the power meters are way off, right side is pretty much stuck in the middle, left meter will not go to zero and moves very little. What could this be now ??
I left it playing for over three days, posted when it was going on two, and by the time the right channel started acting up, it was beginning to sound much better, not sweet or warn in any way, but a lot less shrill or harsh.
Now something else is wrong !!
Fortunately I have the service manual for it, so I'll have to go through the receiver with a multimeter check on voltages etc. I'm worried that considering this receiver actually blew its original caps on the power board, that it might have damaged something else, silicon etc.
I'm also going to recheck that every cap is in the right place and properly soldered as well. BTW I changed all the caps in the power and ampilifer boards.
Did not install bypass caps, but definitely will once I get it sorted out.
Crackling could be a result of bad solder joints. I make about 10% of them & I've been doing this for 55 years. Try pushing on the connections with a wood or plastic stick while the power is on, to find the one that crackles. Not only I make bad joints, some of the really good looking joints in a couple of 90's Peavey products have been bad.
As far as bypass caps, I think the difference between old caps & new is smaller size which would lead to lower self inductance. Ceramic or film smaller bypass caps would decrease the inductance more. I think probably the harsh highs you complain after cap replacement of are more likely to be a speaker problem exagerated by the restored high frequency response of your unit. If you replaced any coupler electrolytic caps, your unit may have had no high frequencies at all previously. To check for speaker distortion, try listening to your amp with decent headphones. I have some rather nice sounding headphones that cost only $40.
I've replaced about 500 ecaps in geriatric amps, preamps, mixers, and organs, and generally get good results with industrial long service life caps from nichicon, rubicon, panasonic, CDE, united chemicon. Other than any bad solder joints. The "settling" in phenomenon reported previously I find to be so much vapor.
To really check your amp for high frequency distortion, try testing it with square wave input. Watch wattage levels, these waveforms are tough on speaker windings. If your scope shows any high frequency ringing after the vertical edge, then further experimentation with compensation is indicated. usually something like mica or ceramic caps added or increased between base & collector of the VAS or drivers is a first approximation of a solution. There are about 60 flavors of compensation to keep amps from ringing or starting to oscillate. Changing the value of the series cap in the feedback path from output to the input is also popular.
As far as bypass caps, I think the difference between old caps & new is smaller size which would lead to lower self inductance. Ceramic or film smaller bypass caps would decrease the inductance more. I think probably the harsh highs you complain after cap replacement of are more likely to be a speaker problem exagerated by the restored high frequency response of your unit. If you replaced any coupler electrolytic caps, your unit may have had no high frequencies at all previously. To check for speaker distortion, try listening to your amp with decent headphones. I have some rather nice sounding headphones that cost only $40.
I've replaced about 500 ecaps in geriatric amps, preamps, mixers, and organs, and generally get good results with industrial long service life caps from nichicon, rubicon, panasonic, CDE, united chemicon. Other than any bad solder joints. The "settling" in phenomenon reported previously I find to be so much vapor.
To really check your amp for high frequency distortion, try testing it with square wave input. Watch wattage levels, these waveforms are tough on speaker windings. If your scope shows any high frequency ringing after the vertical edge, then further experimentation with compensation is indicated. usually something like mica or ceramic caps added or increased between base & collector of the VAS or drivers is a first approximation of a solution. There are about 60 flavors of compensation to keep amps from ringing or starting to oscillate. Changing the value of the series cap in the feedback path from output to the input is also popular.
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I was just checking and two pads are loose/desoldered, will work on it. Hopefully that will be it.
I bought Elna Simlic IIs for the lot except for the reservoir caps. They were all larger than the original caps at the same spec. Went from 6800uF to 10000uF in reservoir, should help but not too big a difference. I tend to think the older ones were on the cheaper side, rather than actually better than the ones in place now. They look cheap, that's about as technical as I can get on that.
I bought Elna Simlic IIs for the lot except for the reservoir caps. They were all larger than the original caps at the same spec. Went from 6800uF to 10000uF in reservoir, should help but not too big a difference. I tend to think the older ones were on the cheaper side, rather than actually better than the ones in place now. They look cheap, that's about as technical as I can get on that.
Hi, I did re-solder the bad solder joints, and it was working really well, but now I am having another rather big crackling issue with the amplifier. Which had stopped after re-soldering.
At some seemingly random point the amp will start to crackle very very loudly, normally it had been only one on the channels, now it's either left or right. This is random also, sometimes left will crackle loudly, sometimes right will. Sometimes both.
It will generally go away on its own after a couple of seconds. But it has become more frequent. The fact that it now involves both channels alternately and simultaneously is new, and really worries me. As it would mean that there is a different problem to the bad soldering joints I had before. If it also much much louder than before.
I turn off the speakers and let it pass, as I can see the power level indicators going berserk. When they stop, this "fit" is over and it's safe to use.
I also noticed that If I turn down the volume it is unaffected, it I change input, it is unaffected, if I move the balance it is unaffected as well. If I increase volume significantly I will hear the music behind the crackling.
Also noticed that bass and treble settings do modify the crackle, if I turn down bass to its lowest setting crackle is a lot less loud.
When it stops it sounds just fine, and will not happen anymore, until it is turned off and then on at a later point.
It would seem that it is a cap that is misbehaving. The cap would seem to be in the signal path, as tone controls affect the noise. While nothing else does. It is not being amplified, as volume control does not affect it.
So ... I just had a look at the amplifiers schematic.
The signal goes to the amplification module from the balance control. Balance does not affect it, so the issue would seem to be in the amp module. The amp module has a tone control loop, part of the amp module albeit on a different board. But tone control does affect it.
So I'm a bit confused now.
I'm trying to narrow it down as much as possible. if I get this, tone affects it, and tone is in the amplification circuit, so it is generated prior to tone controls, clearly not after tone control.
Just prior to tone control, if I'm right.
Would this be correct, any thoughts ?? I'll have to remove both covers and use it open to check, try pushing with a stick or plastic as you suggested until I find something that makes a change. I will try caps on or just prior to the tone control board see if trying to reason this thing out works.
Anyway after it passes it's just fine, but it is annoying and just might fry my speakers, it can be very loud, sometimes it is a repeated ban/crackle, sometimes its just random noise.
Anyway, any suggestions are appreciated.
Manolo
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