thanhky1985
Active Member
I am planning to upgrade the output capacitor from 2,200 to 10,000uf or 20,000uf. Has anyone done this? will it burn my speakers? will it produce better sound? Welcoming all comments
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Sansui 2000a increases the output capacitor
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ConradH
Lunatic Member
IMO, probably a bad idea. You might end up with a big turn-on or turn-off thump and I doubt there will be a sonic improvement. Maybe one step up, like 3300, but I wouldn't do more. Don't change the value of the input coupling caps at all, as it can have unexpected and opposite results from what you might expect.
thanhky1985
Active Member
Yes, I will drop that idea. Because I'm afraid of the sound of the speakers hitting when I turn the amp on and off. Please let me ask more questions.If I increase the power capacitor to 3300uf Will it damage the power transistor for a long time? And at the current 25v source I measured only 22.8v. What do I have to do to increase the volts to the 25v standard?Do I have to replace transistor 2sc971?
sae-7125
Super Member
c821 & c822 ?
some useful info might be floating around in the following thread:
i would imagine that the "exclusively sansui" section of the forum is loaded with notes and experiences.
hifi-wiki.com
marantzhallo-fi.blogspot.com
*good info about rebuild and upgrades.
have to be careful when bumping up power supply caps, current inrush will stress the txf and rectifier diodes. a simple workaround for aggressive inrush would be a soft-start circuit. it is difficult to calculate at what size of capacitance a soft-start system would be needed.
using a simple ntc inline with the mains cord (inside chassis) is quick and easy. going from 2200 up to 4700uf shouldnt be an issue. going up to 10000uf or 22000uf each might stress a few things. i modded a mcintosh mc-2105 power amp from its original 39000uf to 100000uf (0.1 farads) but the amp design had a pre-existing ntc soft-start system which was beefed up a little more. the amp had "bass for days" was one comment.
some useful info might be floating around in the following thread:
Sansui 2000A
Hello all-Anyone out there have an opinion on the 2000A? Seems to be some at pretty resonable prices. I am looking to use as a pre-amp in my main set up. Later will be the main in my bedroom system. Low power (35wpc) I know but how do those 35 wpc sound? Thanks
audiokarma.org
i would imagine that the "exclusively sansui" section of the forum is loaded with notes and experiences.
Sansui 2000 A | hifi-wiki.com
Sansui 2000A Receiver
Sansui 2000A Receiver Today we have a Sansui 2000A receiver to showcase. The 2000 and 2000A/2000X are very similar models besides ...
marantzhallo-fi.blogspot.com
have to be careful when bumping up power supply caps, current inrush will stress the txf and rectifier diodes. a simple workaround for aggressive inrush would be a soft-start circuit. it is difficult to calculate at what size of capacitance a soft-start system would be needed.
using a simple ntc inline with the mains cord (inside chassis) is quick and easy. going from 2200 up to 4700uf shouldnt be an issue. going up to 10000uf or 22000uf each might stress a few things. i modded a mcintosh mc-2105 power amp from its original 39000uf to 100000uf (0.1 farads) but the amp design had a pre-existing ntc soft-start system which was beefed up a little more. the amp had "bass for days" was one comment.
thanhky1985
Active Member
Thank you very much for the above information! And ,Can you explain more clearly what ntc line is?c821 & c822 ?
some useful info might be floating around in the following thread:
Sansui 2000A
Hello all-Anyone out there have an opinion on the 2000A? Seems to be some at pretty resonable prices. I am looking to use as a pre-amp in my main set up. Later will be the main in my bedroom system. Low power (35wpc) I know but how do those 35 wpc sound? Thanksaudiokarma.org
i would imagine that the "exclusively sansui" section of the forum is loaded with notes and experiences.
Sansui 2000 A | hifi-wiki.com
*good info about rebuild and upgrades.Sansui 2000A Receiver
Sansui 2000A Receiver Today we have a Sansui 2000A receiver to showcase. The 2000 and 2000A/2000X are very similar models besides ...
have to be careful when bumping up power supply caps, current inrush will stress the txf and rectifier diodes. a simple workaround for aggressive inrush would be a soft-start circuit. it is difficult to calculate at what size of capacitance a soft-start system would be needed.
using a simple ntc inline with the mains cord (inside chassis) is quick and easy. going from 2200 up to 4700uf shouldnt be an issue. going up to 10000uf or 22000uf each might stress a few things. i modded a mcintosh mc-2105 power amp from its original 39000uf to 100000uf (0.1 farads) but the amp design had a pre-existing ntc soft-start system which was beefed up a little more. the amp had "bass for days" was one comment.
sae-7125
Super Member
my fault, i forgot to add a very important word. ntc "thermistor" (negative temperature coefficient).
The Ultimate Guide to Soft Start Design
Design a soft start circuit for an audio amplifier using an inrush current limiter (ICL) or NTC resistor. See why a soft start is often needed even with small toroidal power transformes.
neurochrome.com
NTC thermistor for inrush current
restoring an amp. While not yet on a dedicated line, when I power it up, the lights dim a fair amount. Started checking into soft start circuits, but after reading a little bit about them, thought it best not to experiment with this amp after reading a few warnings. I then ran across ntc...
www.audiokarma.org
The tricky part about thermistors and solid state gear is the max current vs idle current. Most thermistors are intended to run well above 50% of their max rating in order to have reasonably low resistance. Solid state amps tend to idle at very low current, and significantly increase that with load. It ends up making a weirdly mushy power supply that is pretty sub-optimal. If you want inrush limiting a better way to go is a resistor in the primary that bridges with a relay after some amount of time.
Or just run caps close to the original values and figure it lasted 50 years and will likely be fine for some more time. Do the triac power switch mod if you want to add some insurance to that.
Or just run caps close to the original values and figure it lasted 50 years and will likely be fine for some more time. Do the triac power switch mod if you want to add some insurance to that.
thanhky1985
Active Member
cảm ơn vì thông tin hữu ích, có lẽ tôi sẽ sử dụng các thông số kỹ thuật cũ mà không tăng chúng. nhưng tôi sẽ mua một số mạch trễ có sẵn trên AliExpress để thêm vào amp đèn của mìnhlỗi của tôi, tôi quên thêm một từ rất quan trọng. ntc "nhiệt điện trở" (hệ số nhiệt độ âm).
The Ultimate Guide to Soft Start Design
Design a soft start circuit for an audio amplifier using an inrush current limiter (ICL) or NTC resistor. See why a soft start is often needed even with small toroidal power transformes.
NTC thermistor for inrush current
restoring an amp. While not yet on a dedicated line, when I power it up, the lights dim a fair amount. Started checking into soft start circuits, but after reading a little bit about them, thought it best not to experiment with this amp after reading a few warnings. I then ran across ntc...www.audiokarma.org
Cảm ơn một lần nữa vì sự giúp đỡ của bạn!
thanhky1985
Active Member
thanks for the useful information, i will probably use the old specs without increasing them. but i will buy some delay circuits available on aliexpress to add to my tube amps
thanks again for your help!
thanhky1985
Active Member
thanhky1985
Active Member
thanks for the useful information, i will probably use the old specs without increasing them. but i will buy some delay circuits available on aliexpress to add to my tube ampsmy fault, i forgot to add a very important word. ntc "thermistor" (negative temperature coefficient).
The Ultimate Guide to Soft Start Design
Design a soft start circuit for an audio amplifier using an inrush current limiter (ICL) or NTC resistor. See why a soft start is often needed even with small toroidal power transformes.
NTC thermistor for inrush current
restoring an amp. While not yet on a dedicated line, when I power it up, the lights dim a fair amount. Started checking into soft start circuits, but after reading a little bit about them, thought it best not to experiment with this amp after reading a few warnings. I then ran across ntc...www.audiokarma.org
thanks again for your help!
Blue Shadow
Waiting for Vintage Gear from this century
I know you have been talked out of this but why did you consider it in the first place? I think this unit is cap coupled and those output caps are just there to block DC from getting out. Their value will change the low frequency cutoff down in the 0-5Hz range, generally, a place we don't listen to music and having it cut off is fine. Just curious what made you consider that big change.
I don't know this one specifically, but on other cap coupled amps I've worked on the negative feedback is connected to the speaker side of the cap. The cap value doesn't affect LF response to a significant degree unless its just toast or way undersized.
I've roughly doubled caps before to get something that fit the clamp or hole spacing required but thats about as far as I feel comfortable going.
I've roughly doubled caps before to get something that fit the clamp or hole spacing required but thats about as far as I feel comfortable going.
thanhky1985
Active Member
I only thought of it because I wanted it to have more capacity. Because I have another pair of speakers, polk s15 88db. About 100w. I want the 2000a to conquer it
thanhky1985
Active Member
Are you having problems with the speaker sound when the power switch is turned on?
Blue Shadow
Waiting for Vintage Gear from this century
The output caps in this cap-coupled amplifier are only there for blocking DC and the capacitance of the cap only determines the low frequency cut off as it blocks the very lowest frequencies (and 0Hz or DC). These frequencies are single digits and we don't hear them, the amp doesn't make em much and the speakers never want to see them. But since DC is part of the signal on the cap coupled amp, the cap is needed to block that DC. There is a formula to determine what the different capacitance values should be based on the frequency and impedance. These are common in tube preamps where they feed a few or more thousands ohms input impedance and they are 1-5µF but in an amp feeding an 8Ω speakers the values are in the 2200-5000µF range. That is why I asked why you wanted to change them to something very high.
The single cap is the one that supplies the oomph to the amp and is part of the power supply. Since these amps have only one rail voltage they need only one cap or stacked caps for added capacitance in some units. Upping this will help but it will not change the output level of the amp. The rated watts will remain the same.
So you can save money on the coupling caps as you have decided to do.
thanhky1985
Active Member
Thank you very much for letting me understand more about them.
Blue Shadow
Waiting for Vintage Gear from this century
Can I give you a homework problem? Look up what I talked about and come back with the two frequencies associated with the original cap and your larger cap when using 8Ω speakers.
I had to google this topic when I learned about the 3300?μF coupling caps in the Marantz 1030 I restored. My ‘splainig it here just helps me understand. Problem I had was what value is needed for capacitance, Farad? or some other one. Micro is 10^-6. We use microfarad sized capacitors Take your time, I’ll check back as I go look it up again and determine the answers.
I had to google this topic when I learned about the 3300?μF coupling caps in the Marantz 1030 I restored. My ‘splainig it here just helps me understand. Problem I had was what value is needed for capacitance, Farad? or some other one. Micro is 10^-6. We use microfarad sized capacitors Take your time, I’ll check back as I go look it up again and determine the answers.
Blue Shadow
Waiting for Vintage Gear from this century
The change from 3300 to 10-20k didn’t show much at all in the straight calculation either, both results being below 6Hz, IIRC.
I’m just pointing out coupling caps are not power storage caps for improved bass but approach a size where folks start thinking they should throw in a bigger one. All cause of the recapping frenzy that is the waters of ak.
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