| beppe61 |
Dear Sirs,
I have bought a 30 years old integrated amp.
How can I assess if the capacitors (originals) must be replaced?
Aestetichally they appear in good shape.
There is no form of leakage or other.
They are SPRAGUE 36DX and rated 7200 uF /50 VDC.
There is also a serial number 7552.C.
Thank you so much.
Kind regards,
beppe61 |
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| RetroAudio |
| I think the question is: do you WANT to replace them? |
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| beppe61 |
Dear Mr. Tony,
thank you very much for your kind and extremely valuable reply.
If I understand well your point is that ESR tends to get higher with the time (plaese excuse my naive english).
So the charging and discharging speed slows down.
Have I understood well ?
Thank you again very much.
Kind regards,
beppe61 |
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| beppe61 |
| quote: | Originally posted by RetroAudio
I think the question is: do you WANT to replace them? |
Dear Sir,
to be honest, yes.
Please let me explain a little and then kindly ask you a question.
I have noticed that all the power amps with great dynamic properties have very big capacitors.
On average I can find 20.000 uF /channel of capacitance in the power supply.
In my 70+70 W stereo amp there are only two of this very good Sprague 7200 uF caps.
It seems too little to me indeed.
So yes, I would like to increase the capacitance at least to, let's say, 15.000 uF x 2 , doubling the total capacitance in the pS.
Then let me to ask you a question.
I have still a big doubt about power supply.
With short term impulsive signals which are more important: the caps or the transformer?
A friend of mine told me that only caps deal with short term impulsive signals so the dynamic capability of the amp are related to the electricale properties of the caps (ESR, capacitance).
I really do not know if this is true or not.
But if it is true, then fitting very good big caps should improve things in an evident manner.
Thank you so much for your kind reply.
Kind regards,
beppe61 |
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| RetroAudio |
| well beppe61, this is partially true and thus part of the story. Good caps are always welcome in a power supply no matter what, but one needs to remember that the transformer isn't exactly invisible here. It does refresh the caps at a rate up to 120 times/sec and is therefore in parallel with the caps supplying current to the circuit's demands. Although signal peaks or dynamics can be quicker than that rate, they can occur at the same instant that refreshes take place. Also something else to think about is that bigger is not always better, a notion not too popular with some around here to be sure. Perhaps doing some light reading on the subject to form your own ideas would be a positive step. |
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| I_Forgot |
| quote: | Originally posted by beppe61
I have bought a 30 years old integrated amp.
How can I assess if the capacitors (originals) must be replaced?
Aestetichally they appear in good shape.
There is no form of leakage or other.
They are SPRAGUE 36DX and rated 7200 uF /50 VDC. |
There are several things to consider:
How old is the equipment?
30 years is old enough to warrant wholesale replacement of all
electrolytic caps. Electrolytics are the least reliable electronic
components.
How much will it cost?
This size cap is dirt cheap. In fact, put in a bit more capacitance
while you're at it. Modern electrolytic caps are about 1/2 the size
of 30 year old caps, so even if you get 2X the capacitance, it will probably fit in the available space. All this assumes you will do the work yourself. If you have to pay someone to do it, it probably isn't worth it unless the equipment is something really special.
How easy are they to get?
You can get them from any electronics distrbutor or surplus outlet.
All things considered, I'd say replace them.
I_F |
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| wintermute |
Hi beppe61,
Yes the esr gets higher as the cap gets older.... I'm not sure whether your description of why this is a problem is correct or not ;) I just know it isn't desirable :)
here is another link, which tells the different ways you can use an esr meter to tell if a cap is bad. This one is a bit closer to home too!
http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
Tony. |
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| anatech |
One thing you can try. Hang an oscilloscope on the capacitors and look at the waveform. If the ESR is getting high, you will see "pips" on the leading edge of the waveform. This gets more pronounced as the ESR and inductance goes up. So will any music waveforms. Try it.
-Chris |
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| beppe61 |
| quote: | Originally posted by RetroAudio
well beppe61, this is partially true and thus part of the story. Good caps are always welcome in a power supply no matter what, but one needs to remember that the transformer isn't exactly invisible here. It does refresh the caps at a rate up to 120 times/sec and is therefore in parallel with the caps supplying current to the circuit's demands. Although signal peaks or dynamics can be quicker than that rate, they can occur at the same instant that refreshes take place. Also something else to think about is that bigger is not always better, a notion not too popular with some around here to be sure. Perhaps doing some light reading on the subject to form your own ideas would be a positive step. |
Dear Sir,
thank you sincerely for your extremely kind and above all valuable reply.
My idea of increasing capacitance in the PS is driven by some considerations.
Some very well regarded power amps sport really huge capacitance in their PS.
The Krell KSA 50, if I am not wrong, has 4 x 40.000 uF/each caps. :bigeyes:
Odyssey Audio offers a caps upgrade in their amps.;)
This must mean something.
I understand that caps is not the full story.
There is also the trasformer that acts.
My problem is:
if I want to upgrade the PS do I have to start with caps or with transformer?
Thank you very much again for your kind and valuable suggestion.
Kind regards,
beppe61
ITALY |
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| beppe61 |
Thank you very much Sir for your kind and valuable reply.
Let me please quote you:
| quote: | Originally posted by I_Forgot
> There are several things to consider:
How old is the equipment?
30 years is old enough to warrant wholesale replacement of all
electrolytic caps.
Electrolytics are the least reliable electronic components.
How much will it cost?
Yes, the unit is about 30 years old unit.
It was quite good in its time. The caps replacement and upgrading (I am thinking of doubling the capacitance) should be cheap.
I am also thinking to remove the trasformer and put it in a separate case to make room for the new caps.
> This size cap is dirt cheap. In fact, put in a bit more capacitance
while you're at it. Modern electrolytic caps are about 1/2 the size
of 30 year old caps, so even if you get 2X the capacitance, it will probably fit in the available space. All this assumes you will do the work yourself. If you have to pay someone to do it, it probably isn't worth it unless the equipment is something really special.
All by myself (Aduio it is my main hobby and I want to try to so something).
> How easy are they to get?
You can get them from any electronics distrbutor or surplus outlet.
All things considered, I'd say replace them.
I_F |
Dear Sir,
thank you so much for your extremely kind and helpful comment.
Do you have any suggestion on brands particularly good for audio purpose?
At the end I will need 2 caps 15.000-20.000 uF each / 63 VDC (to stay safe).
Kind regards,
beppe61 |
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| beppe61 |
| quote: | Originally posted by wintermute
Hi beppe61,
Yes the esr gets higher as the cap gets older.... I'm not sure whether your description of why this is a problem is correct or not ;) I just know it isn't desirable :)
here is another link, which tells the different ways you can use an esr meter to tell if a cap is bad. This one is a bit closer to home too!
http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
Tony. |
Dear Mr. Tony,
thank you so much for your kind and very helpful information.
I have provided me with a lot of interesting things to study in depth in the weekend.
Thank you so much.
Kind regards,
beppe61 |
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| wintermute |
| quote: | Originally posted by beppe61
My problem is:
if I want to upgrade the PS do I have to start with caps or with transformer?
ITALY |
Hi beppe61,
that is going to depend on the design of the existing PS.... sometimes large capacitors are used to "prop up" an inadequate transformer....... if the transformer has enough VA to provide continuous current to the amp, when it is running at full load, and it doesn't make any noise (mechanical or electromagnetic) then you probably don't need to worry about it.
As for the caps, if you have an adequate transformer (as described above) then if there is enough capacitance to reduce the ripple to an acceptable level, then there probably is no gain to be made by putting in more capacitance. You may of course be able to use "better" capacitors of the same value for an improvement in sonics, as RetroAudio said more isn't necessarily better, have a read of Hugh Dean's ideas on power supplies here ---> http://www.aksaonline.com/discussio...rs_psupply.html
Tony.
PS. you don't need to be so formal ;) a hi Tony would be fine :) |
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| beppe61 |
| quote: | Originally posted by anatech
One thing you can try.
Hang an oscilloscope on the capacitors and look at the waveform. If the ESR is getting high, you will see "pips" on the leading edge of the waveform. This gets more pronounced as the ESR and inductance goes up. So will any music waveforms. Try it.
-Chris |
Dear Mr. Chris,
thank you so much for your extremely kind and interesting reply.
What you suggest me is out of my possibility for pratical reason.
I have already problems to concile my audio hobby with the family.
Anyway I have already decided to replace them and doubling the capacitance with very good new ones.
It is a try.
I will see.
Thank you very much again.
Kind regards,
beppe61 |
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| beppe61 |
| quote: | Originally posted by wintermute
Hi beppe61,
that is going to depend on the design of the existing PS.... sometimes large capacitors are used to "prop up" an inadequate transformer....... if the transformer has enough VA to provide continuous current to the amp, when it is running at full load, and it doesn't make any noise (mechanical or electromagnetic) then you probably don't need to worry about it.
As for the caps, if you have an adequate transformer (as described above) then if there is enough capacitance to reduce the ripple to an acceptable level, then there probably is no gain to be made by putting in more capacitance. You may of course be able to use "better" capacitors of the same value for an improvement in sonics, as RetroAudio said more isn't necessarily better, have a read of Hugh Dean's ideas on power supplies here ---> http://www.aksaonline.com/discussio...rs_psupply.html
Tony.
PS. you don't need to be so formal ;) a hi Tony would be fine :) |
Well, Hello Tony,
thank you so much again for your really kind, friendly and valuable comments.
As I said to RetroAudio, my idea of increasing capacitance in the PS is driven by some considerations.
Some very well regarded power amps sport really huge capacitance in their PS.
The Krell KSA 50, if I am not wrong, has 4 x 40.000 uF/each caps.
Once I listened to the KSA 50.
What a wonderful amp !
Odyssey Audio offers a caps upgrade in their amps.
This must mean something.
I understand that caps is not the full story.
There is also the transformer that acts.
The transformer should be about 600 VA.
All considered I am thinking of doubling the capacitance and pull the transformer out of the case to make room for the new caps.
Do you think it should be a wise move ?
Kind regards,
beppe61 |
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| wintermute |
Hi Beppe61,
Well I don't know enough about the subject to really make any definitive comments, but at the risk of starting a war, I'll say this:
Sometimes companies do things not because it is better but because it will sell more!
I'm not saying this is the case with the Krell, but is it beyond the realms of possibility??...
Think about Joe Richman, he's looking for something that he can use to impress his rich mates. He takes a look at the Krell and says wow this amp has 160,000uF in the power supply, Bobs amp has 40,000uF, I'll show him. (I'm in no way implying that all buyers of a Krell would have this motive ;) )
We are talking about pretty high end equipment here, and sometimes at this end of the market it is as much (or more) about brag factor than about sound quality. I haven't listened to a Krell (that I can remember) so these are all completely speculative and opinionated words ;) I'm just a bit cynical by nature :)
8<----------------------------------------------------------------------------------
end sarcasm and cynisism
Really I can't say whether it is a wise move or not. It might be, you may get a big improvement, but then again maybe you won't.... It's a chance you will have to take, unless someone else who has this amp and has done the same modification pops in and tells you what their experience was.
Tony. |
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| beppe61 |
| quote: | Originally posted by wintermute
Hi Beppe61,
Well I don't know enough about the subject to really make any definitive comments, but at the risk of starting a war, I'll say this:
Sometimes companies do things not because it is better but because it will sell more!
I'm not saying this is the case with the Krell, but is it beyond the realms of possibility??...
Think about Joe Richman, he's looking for something that he can use to impress his rich mates. He takes a look at the Krell and says wow this amp has 160,000uF in the power supply, Bobs amp has 40,000uF, I'll show him. (I'm in no way implying that all buyers of a Krell would have this motive ;) )
We are talking about pretty high end equipment here, and sometimes at this end of the market it is as much (or more) about brag factor than about sound quality. I haven't listened to a Krell (that I can remember) so these are all completely speculative and opinionated words ;) I'm just a bit cynical by nature :)
8<--------------------------------------------------------------------------------
end sarcasm and cynisism
Really I can't say whether it is a wise move or not. It might be, you may get a big improvement, but then again maybe you won't.... It's a chance you will have to take, unless someone else who has this amp and has done the same modification pops in and tells you what their experience was.
Tony. |
Hi Tony,
thank you sincerely for your extremely kind, nice, honest and very valuable indeed reply.
I would like to elaborate a little my opinion.
The Krell, which had indeed a huge PS, IMHO sounded terrific.
Please let me stress "TERRIFIC".
That said I do not really know if this performance came from those 4 beer can sized caps, but I have the sensation that it could be related also to them, at least partially.
What terrified me in particular was the bass.
I have never heard a bass like that. Think of an heartquake.
It was an experience even shocking .
Of course there is no hope to achieve the room-shaking bass of the Krell with my amp, but I would like to increase the bass power just a little and I am starting to think that doubling the capacitance should be a reasonable move.
After all also a not overtly expensive experiment.
I will report on it.
Thank you very much again,
Kind regards,
beppe61 |
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| jacco vermeulen |
| quote: | Originally posted by wintermute
but at the risk of starting a war |
Isn't it hot enough already where you are, WM ?
Beppe, care to tell the type and brand of your amplifier ? |
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| beppe61 |
| quote: | Originally posted by jacco vermeulen
Isn't it hot enough already where you are, WM ?
Beppe, care to tell the type and brand of your amplifier ? |
Dear Mr. Vermeulen,
thank you very much for your kind reply.
The amp is identical to the following:
http://cgi.ebay.it/STEG-Amplificato...1QQcmdZViewItem
It sports a pre-main splitting option and I currently use only the power amp section.
The pre section is much a cheap addition because the power amp part was also sold as power amp only in another case option.
What is your opinion?
Kind regards,
beppe61 |
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| wintermute |
| quote: | Originally posted by jacco vermeulen
Isn't it hot enough already where you are, WM ?
|
Yes maybe I should have chosen my words more carefully ;)
Tony. |
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| peranders |
My contribution to this is: If it ain't broken don't fix it.
If the amp works good, don't do anything. There are always a risk messing things up and impossible to repair later. Replace parts only if you have to.
A thirty years old cap might have many years left if it has not been put out for high temperatures. |
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| wintermute |
Very sage advice Peranders :) having been there done that, I wholeheartedly agree :D (though I did get it back to working properly in the end ;) )
Tony. |
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| beppe61 |
Dear Mr. Peranders,
thank you so much for your kind and very valuable reply.
Let me please ask you further opinions between the lines.
| quote: | Originally posted by peranders
> My contribution to this is: If it ain't broken don't fix it.
If the amp works good, don't do anything.
The fact at Odyssey Audio, a well considered audio company, offers caps increase made me think about the possibility.
And it seems indeed that a lot of their customers pay for it.
Without having their amps broken anyway.
> There are always a risk messing things up and impossible to repair later.
that is indeed a risk and a point.
But it is a sort of experiment. and what if the outcome would be remarkable?
It costs about 20 USD of surplus Sprague, Mallory ...
> Replace parts only if you have to.
I read that just replacing an electrolytic caps in series with the signal with a film one has a nice improvement in the sound.
> A thirty years old cap might have many years left if it has not been put out for high temperatures. |
Nice to hear this. Sprague make great caps indeed.
My amp should be of the 1978 and they seem to work just fine.
But i don't know about their ESR now.
Thank you so much.
Kind regards,
beppe61 |
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| wintermute |
| quote: | Originally posted by beppe61
But i don't know about their ESR now.
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Hi beppe61,
This may not be an issue. I tested (measured) with speaker workshop some 16 yo caps I took out of my amplifier.
Now I'm not sure if the resistance that speaker workshop reports is ESR ( I'm assuming it is) but the 16 YO generic brand caps actually had lower resistance than brand new panasonic FC caps of the same value and voltage!!! (I can't remember the exact figures but I think it was something like 6 ohms for the panasonic, 3 ohms for the old ones, and 1.5 ohms for rubycon ZA) All were 10uf 16V from memory. I wondered whether it had been wise to replace them!! having said that I only checked two, and the amp did sound better ( the bass improved) after changing the caps out (note these weren't the power supply caps).... It is of course possible that I only thought I could hear a difference, but that is a whole other kettle of fish ;)
Tony. |
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| jacco vermeulen |
Beppe already made up his mind, i think.
Bartolomeo Aloia is the Nelson Pass of Italy.
I believe STEG is mainly in the car audio business nowadays.
If the amplifier you have is virtually the same as the one on Ebay it is a very fine looking amplifier, 30 years ago it must have been a luxury amplifier.
Even so, every commercial audio designer needs to monitor costs, the likes of Krell also.
Every dollar spent on parts raises the price tag by 5 to 6 dollars of the end product for high grade equipment.
The multiplication factor for consumer electronics is likely to be in the order of 10.
For an integrated amplifier choosing between a 7200uF or 15.000 uF capacitor will also be cost driven.
imo, replacing capacitors that were produced in the 52th week of 1975 is not a bad option.
Replacing them by bigger ones could be an improvement, but you'd have to check the rest of the powersupply, and see what the output stage is like.
But the looks, the choice of capacitors, and the name of the designer this must be a high quality design.
There is no point comparing an integrated class AB amplifier with a US high bias class A amplifier.
Putting 160.000uF in a vintage integrated amplifier is a waste of money and asking for problems.
Turning a classic Lancia Fulvia into a thoroughbred Ford Mustang is bad taste.
Maybe such a goodlooking Aloia design should be kept original.
No doubt there is room for upgrading, i have had very good results replacing and adding parts in amplifiers, such as; capacitors, resistors, transistors,opamps and different wiring.
Do you have the possibility of making/showing us a picture of the interior, Beppe ? |
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| beppe61 |
| quote: | Originally posted by wintermute
Hi beppe61,
This may not be an issue.
I tested (measured) with speaker workshop some 16 yo caps I took out of my amplifier.
Now I'm not sure if the resistance that speaker workshop reports is ESR ( I'm assuming it is) but the 16 YO generic brand caps actually had lower resistance than brand new panasonic FC caps of the same value and voltage!!! (I can't remember the exact figures but I think it was something like 6 ohms for the panasonic, 3 ohms for the old ones, and 1.5 ohms for rubycon ZA) All were 10uf 16V from memory. I wondered whether it had been wise to replace them!! having said that I only checked two, and the amp did sound better ( the bass improved) after changing the caps out (note these weren't the power supply caps).... It is of course possible that I only thought I could hear a difference, but that is a whole other kettle of fish ;)
Tony. |
Hello Tony,
very interesting experience of yours.
I am already sold on the idea of replacing them.
Now I have only to find 2 nice 15 or 20.000 uF.
Thank you very much again.
kind regards,
beppe61 |
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| Tweeker |
| The Krell is a class A amp, such amps demand very large capacitances in the power supply to reduce ripple as they are always drawing heavy continuous curents. Id probably replace the 30 year old caps with somewhat larger ones too. Dramatically increasing thier size may lead to problems with inrush currents and stress the rectifiers and transformer. |
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| beppe61 |
Hello Jacco,
nice to hear that Aloia is also known in The Netherlands.
>| quote: | Originally posted by jacco vermeulen
Beppe already made up his mind, i think.
Bartolomeo Aloia is the Nelson Pass of Italy.
He is indeed one of the most famous (maybe the most) of italian audio designers.
This is a quite old (but still nice) design. Low global feedback, few parts, powerful power supply, nice components for its time.
I think they were hand-made and tested one by one.
> I believe STEG is mainly in the car audio business nowadays.
If the amplifier you have is virtually the same as the one on Ebay it is a very fine looking amplifier, 30 years ago it must have been a luxury amplifier.
Yes, same model. May be just a little more used.
It was about the equivalent of about 400 euro in the 1978.
> Even so, every commercial audio designer needs to monitor costs, the likes of Krell also.
Every dollar spent on parts raises the price tag by 5 to 6 dollars of the end product for high grade equipment.
The multiplication factor for consumer electronics is likely to be in the order of 10.
For an integrated amplifier choosing between a 7200uF or 15.000 uF capacitor will also be cost driven.
imo, replacing capacitors that were produced in the 52th week of 1975 is not a bad option.
Thank you jacco. So you approve the idea of the replacement ?
If only I could get a drop more in the bass.
I have compared this amp with a pair of Albarry monos and honestly there is no comparison in favour of the english amps.
Through the red front panel anyway I can see a 500 VA transformer and two huge caps.
Nice amps these Albarry.
> Replacing them by bigger ones could be an improvement,
I really hope so.
> but you'd have to check the rest of the powersupply
600 VA transformer. discrete diodes bridge. all in all nice.
> and see what the output stage is like.
a single pair of BJT in metallic case. I have to read the model.
the amp is specified at 70 W/channel with 8 ohm and about 100 W with 4 ohm loads.
> But the looks, the choice of capacitors, and the name of the designer this must be a high quality design.
I agree completely here. Actually I like its clean and punchy sound.
> There is no point comparing an integrated class AB amplifier with a US high bias class A amplifier.
Putting 160.000uF in a vintage integrated amplifier is a waste of money and asking for problems.
What do you think of 2 nice blue high-grade americans of about 15.000 or 20.000 uF?
Could you suggest any particular brand and model?
> Turning a classic Lancia Fulvia into a thoroughbred Ford Mustang is bad taste.
I cannot agree more. different cars for different tastes.
> Maybe such a goodlooking Aloia design should be kept original.
This amp will be like a test bench. As I said I am trying to get just some bass out of it.
> No doubt there is room for upgrading, i have had very good results replacing and adding parts in amplifiers, such as; capacitors, resistors, transistors,opamps and different wiring.
very interesting. I would like to have time to do the same.
I like very much the idea of restore audio things.
> Do you have the possibility of making/showing us a picture of the interior, Beppe ? |
I will try to get a digital camera, that I do not own myself and shot some photos.
The power amp has a nice modular structure. Very interesting and possibility to extract these modules for any purpose.
Dear Jacco, as I understand you have a great experience on audio equipment mods, would you mind if I contact you privately?
Thank you very much again for your kind and very valuable reply.
Kind regards,
beppe61 |
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| beppe61 |
Thank you Mr. Tweeker for your kind and precious advice.
| quote: | Originally posted by Tweeker
> The Krell is a class A amp, such amps demand very large capacitances in the power supply to reduce ripple as they are always drawing heavy continuous curents.
Of course, but in AB design there is the need to cope with impulsive high demands of current during musical peaks.
I think that a fast and big capacitance reservoir is always a nice plus.
> Id probably replace the 30 year old caps with somewhat larger ones too. Dramatically increasing thier size may lead to problems with inrush currents and stress the rectifiers and transformer. |
Do you think that just doubling the total capacitance could cause some problems like those you mention ?
After all 30 years are always 30 years.
If one reads the lifetime value of caps I think that time has arrived.
Thank you very much again and kind regards,
beppe61 |
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| maxlorenz |
Dear Beppe:
I am probably the least indicated to advice you but I value your interest in renewing your amp's life :)
My (limited) experience comes from building Hypex' UCD180 ClassD amp: an easy and rewarding experience. As these are modules one only has to put together the PS and connections. Believe me the sound is first class and the bass is excellent, not floor shaking but deep, expansive and articulated.
I'm sure you will notice an improvement in sound when you upgrade but first check rectifier's current capacity (they are cheap) and soft start (for your 600VA Tx).
Well, I have tried these caps:
1)BHC ALS40 (RS nº 381-9908 ) which are very good sounding, with excellent bass and a bit dark presentation.
2) Epcos Sikorel(RS nº 190-8955 ): great sounding, more transparent-detailed.
Those caps are NOT cheap! And probably overkill on your project, but in mine they were terrific. Note that this is a very personal opinion of caps that I found at RS components (search the site for better options).
You may consider these RIFA (RS nº189-793 ) wich are said to be very good and cheaper.
You may also consider changing the stock power cord and speaker/RCA connectors and internal wiring.
Appart that, I must say that I think you are a very kind and polite person and that your posts are a delice to read :)
I hope this helps :angel:
Mauricio |
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| Tweeker |
| Doubling it will probably be ok, increasing it to 160,000 uF might be another matter. As Mauricio said rectifiers are cheap, check them. I dont know what it looks like in there, but if its easy to do so, you may do better to use say a 7,200uF cap + a 12,000uF cap per rail than one 20,000 uF cap. |
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| beppe61 |
| quote: | Originally posted by maxlorenz
Dear Beppe:
I am probably the least indicated to advice you but I value your interest in renewing your amp's life :)
My (limited) experience comes from building Hypex' UCD180 ClassD amp: an easy and rewarding experience. As these are modules one only has to put together the PS and connections. Believe me the sound is first class and the bass is excellent, not floor shaking but deep, expansive and articulated.
I'm sure you will notice an improvement in sound when you upgrade but first check rectifier's current capacity (they are cheap) and soft start (for your 600VA Tx).
Well, I have tried these caps:
1)BHC ALS40 (RS nº 381-9908 ) which are very good sounding, with excellent bass and a bit dark presentation.
2) Epcos Sikorel(RS nº 190-8955 ): great sounding, more transparent-detailed.
Those caps are NOT cheap! And probably overkill on your project, but in mine they were terrific. Note that this is a very personal opinion of caps that I found at RS components (search the site for better options).
You may consider these RIFA (RS nº189-793 ) wich are said to be very good and cheaper.
You may also consider changing the stock power cord and speaker/RCA connectors and internal wiring.
Appart that, I must say that I think you are a very kind and polite person and that your posts are a delice to read :)
I hope this helps :angel:
Mauricio |
Dear Mr. Mauricio,
thank you very much for your extremely kind compliments and valuable advice.
Anyway I must confess you that my politeness is not natural at all.
Instead it is a sneaky strategy to steal precious schematics and information to generous audio experts as you.
Now you can better understand what kind person am I.
Knowledge is a precious thing and I must admit that I am here to take profit of the knowledge of other persons.
I am a RS Components customer as well and I read great things about the brands you mention. Really good products.
That said, I think that the costs of just two new caps of the brands you mention is higher than the residual value of my amp.
I think that the Sikorel are 10.000 uF/63 VDC, if I am not mistaking.
I would like to try before two surplus caps of about 15.000 uF.
I have a wonderful opinion of those blue american caps of brands like Mallory, Sprague Powerlyitc (in teh name there is all the programm), Cornell Dubillier, Sangamo, United ChemiCon.
The fact that brands like Mark Levinson, Krell use them speaks for itself I think.
On the basis of your very kind and friendly reply I would like to ask you which kind of preamp do you use to drive your Hypex' UCD180 modules.
As you can see from my other threads I am also obsessive in my search for a minimalist line preamp to use along with the digital source to drive this amp I am trying to power up.
Thank you very much again for your extremely nice and kind words.
Kind regards,
beppe61
ITALY |
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| beppe61 |
Dear Mr. Tweeker,
thank you very much again for your kind and helpful advice.
>| quote: | Originally posted by Tweeker
Doubling it will probably be ok,
Thank you. This is the value I will try. I do not expect much but I will not be satisfied until I try.
Well to be perfectly honest I expect a nice improvement in the bass region of the audio spectrum. Maybe I am too optimistic.
> increasing it to 160,000 uF might be another matter.
It would mean more than ten times the present value of capacitance. I understand very well your point.
> As Mauricio said rectifiers are cheap, check them.
All right.
> I dont know what it looks like in there, but if its easy to do so, you may do better to use say a 7,200uF cap + a 12,000uF cap per rail than one 20,000 uF cap. |
I record your valuable suggestion.
Thank you very much again.
Kind regards,
beppe61 |
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| RetroAudio |
| beppe61 - you sure got all sorts of advice here, just hope you can make sense of it all. or,....are you sorry you asked??..:bigeyes: |
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| wintermute |
hehehe @ Retro ;)
I have had Nichicon KG caps highly recommended :) if you can't get them in Italy, Percy Audio http://www.percyaudio.com/ has them at reasonable prices :)
Tony. |
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| maxlorenz |
Dear Beppe:
| quote: | | Instead it is a sneaky strategy to steal precious schematics and information to generous audio experts as you. |
Ha, ha, ha :D :D :D sonno morto di tanto ridere...
Your strategy (the same that I use) works.
I have never being called an audio expert and I'm very flatted, although without ANY fundament. ;)
No, I consider myself an "ethernal beginner" (I read this description somewhere and I found it genial). In fact we could form here an ethernal beginners' guild.
| quote: | | I think that the Sikorel are 10.000 uF/63 VDC, if I am not mistaking. |
And and insane beginner I must admit :D Once I heard that Halcro amps used sikorel and was irremediably lost!
| quote: | | On the basis of your very kind and friendly reply I would like to ask you which kind of preamp do you use to drive your Hypex' UCD180 modules. |
For now I use the UCD's amps on my second rig, an active speaker setup with cheap analog Behringer crossover as preamp wich has "servobalanced" outs. The DDDAC1543 with a 16*TDA1543 chips tower is the source.
My plan is substituting my ClassA amps in my main system with a pair of UCD400 monos when I get the money to buy more "cans".
Projected system:
CDPRO-2M->Monarchy Audio DIP upsampler->heavily moded M-audio superDAC through balanced outs->balanced transformer based volume control with Stevens&Billingtons trannies->UCD400
:cool: All balanced...
What the ***, it's only money.:D
I like very much the TVC approach both sonically and phylosophically. And they match the UCD's wonderfully.
Arrivederci, mio caro... :)
Maurizio :D |
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| beppe61 |
| quote: | Originally posted by RetroAudio
beppe61 - you sure got all sorts of advice here,
just hope you can make sense of it all. or,....
are you sorry you asked??..:bigeyes: |
Dear Sir,
I am very happy indeed I asked.
I got a lot of very kind, friendly and above all extremely valuable advice from you and the other participants to the discussion.
Thank you so much.
Kind regards,
beppe61 |
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| beppe61 |
| quote: | Originally posted by wintermute
hehehe @ Retro ;)
I have had Nichicon KG caps highly recommended :) if you can't get them in Italy, Percy Audio http://www.percyaudio.com/ has them at reasonable prices :)
Tony. |
Hello Tony,
thank you so much for your kind and extremely valuable suggestion.
Yesterday I actually saw 4x10.000 uF Nichicon caps (don't remember the exact series) in the power supply of the BAT integrated.
This confirms in some way your great suggestion.
Thank you so much.
Kind regards,
beppe61 |
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| beppe61 |
Dear Maurizio,
thank you again for your kind and very helpful reply.
I would like to quote you and reply between the lines.
| quote: | Originally posted by maxlorenz
Dear Beppe:
Ha, ha, ha :D :D :D sonno morto di tanto ridere...
Your italian is really good. Congratulations!
I would like my spanish were good like your italian.
> Your strategy (the same that I use) works.
I have never being called an audio expert and I'm very flatted, although without ANY fundament. ;)
No, I consider myself an "ethernal beginner" (I read this description somewhere and I found it genial).
In fact we could form here an ethernal beginners' guild.
And and insane beginner I must admit :D
I really think that you are much more than a simple beginner and your experience is evident from your replies.
On the other hand I am very inexperienced instead.
> Once I heard that Halcro amps used sikorel and was irremediably lost!
That is a very good method: looking at the parts used in high-end amps is a good way to select them.
> For now I use the UCD's amps on my second rig, an active speaker setup with cheap analog Behringer crossover as preamp wich has "servobalanced" outs.
The DDDAC1543 with a 16*TDA1543 chips tower is the source.
My plan is substituting my ClassA amps in my main system with a pair of UCD400 monos when I get the money to buy more "cans".
Projected system:
CDPRO-2M->Monarchy Audio DIP upsampler->heavily moded M-audio superDAC through balanced outs->balanced transformer based volume control with Stevens&Billingtons trannies->UCD400
:cool: All balanced...
What the ***, it's only money.:D
I like very much the TVC approach both sonically and phylosophically.
And they match the UCD's wonderfully.
Your set up is much more complex than mine.
My system is very basic and I am trying to imporve it just a little in the bass department.
Anyway thank you for your interesting suggestion of the UCD modules.
Arrivederci, mio caro... :)
Maurizio :D |
Hasta la vista, Maurizio ! |
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| maxlorenz |
Caro Beppe:
Allow me to quote you.
| quote: | | Your italian is really good. Congratulations! |
When one is a longtime opera fan one finally ends by learning something ;)
"Oh rustici, Oh rustici,
attenti! non fiatate!
Io giá suppongo é immagino,
que al par di me sapiate
qu'io sonno quel gran medico,
dottore enciclopédico,
chiamatto Dulcamara,
la cui virtú preclara
e il portenti infiniti,
son noti a l' universo
e...e a d'altri siti..."
... from Dulcamara's presentation aria, L'Elisir d'Amore", G Donizetti. :D (sorry for the mistakes )
| quote: | | My system is very basic and I am trying to improve it just a little in the bass department. |
May I suggest that you address your source first? ;)
Good luck
Mauricio |
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| beppe61 |
Dear Maurizio,
thank you again for your always kind and appreciated reply.
You say: "May I suggest that you address your source first? ;)
Good luck
Mauricio [/B][/QUOTE]
Well I have to tell you that I have tried a different power amp in my system (two english Albarry monos, don't know the model) leaving all others things equal.
The bass was very much more powerful and the sound seemed more developed and complete.
These monos are specified at 45W/8ohm and 90W/4ohm, and this should tell something about their current delivery.
That said, someone told me to try to replace the almost 30 years old caps with something new and above all suspicions, increasing also the total capacitance (as I said my idea is to double it).
All in order to get a little more body in the sound.
I have taken a look to the transformer and it seems quite powerful.
The diodes are discrete and quite bulky.
So I am thinking about two 15.000 uF/63V new caps of the like of Sprague, Mallory, Sangamo, ecc.
I will see in the next days.
They usually don't come cheap and I will have to shop around to find a nice price.
Thank you very much again for all your very kind support.
Kind regards,
beppe61 |
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| Tweeker |
| The reason I suggested 2 capacitors per rail is that for a given cap you get near half the esr and esl. Sometimes its even cheaper to boot. But, if its a hassle and you would have to tear stuff up to install them, it would be ill advised. |
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| beppe61 |
Dear Sir,
thank you very much indeed for you kind and helpful advice.
Let me quote you hereunder:
>| quote: | Originally posted by Tweeker
The reason I suggested 2 capacitors per rail is that for a given cap you get near half the esr and esl.
I see very well your point.
What I am trying to get is just a little more bass response.
Anyway I am not sure that a recapping could give that.
I will never know until I try.
> Sometimes its even cheaper to boot.
This is very interesting indeed.
But, if its a hassle and you would have to tear stuff up to install them, it would be ill advised. |
Thank you so much for your kind advice.
Kind regards,
beppe61 |
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| beppe61 |
Dear Friends,
at the end I did it today.
I have replaced the two almost 30 years old Sprague 7200uF/50V capacitors with two new Rifa 10.000uF/63V of the PEH 200 series.
I have chosen these caps above all for:
1) size compatibility
2) good specifications
3) reasonable price.
I have given up the idea of using two huge Siemens Sikorel 15.000uF/100V for size problem (just for the moment anyway).
They are sly in a box, resting and waiting for their turn.
Straight away I do not have any particular problem to report (no noise, no smoke !).
Hopefully I did not make any mistake in connecting them !
Unbelievable.
It seems that the diodes have withstood the bigger current draw at the start up.
I do not want to be too much optimistic but my impression after just two hour of listening are quite positive.
Less noise and ... more powerful sound on the bass (my inmost goal).
Before go out in the garden shouting: "Victory, victory !!!" I think it is better to wait some days of burn-in.
If I seem too much enthusiastic about this simple "operation" just think this is my very first time !
I have used this old amp to assess the influence of filter caps on the overall sound.
I will report my opinion after two weeks of burn-in.
I take the opportunity to thank all of you for your extremely kind, friendly, patient and very valuable support and advice.
Thank you.
Kind regards,
beppe61
ITALY |
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| PB2 |
Hi beppe61 hope things are good with you,
I'm a bit late here but I wanted to mention a few things. Numbers like 7552 are typically date codes. The cap was manufactured in the 52 week of 1975 which agrees with your comment of 30 years old.
A power amp with unregulated supplies, lets say something like 50W/ch, will idle with about +/- 40 V on the power supply. If you load it with a dummy load and drive it to clipping on a bench, the supply will sag typically to about +/- 30V for this type of amp and more 60/50 Hz ripple will be present.
Now remember that power = V^2/R so if the supply stayed at +/-40 it would be able to deliver much more power, and indeed this is where the dynamic headroom comes from. The supply does not sag much during short peaks in the music and the amp can deliver more power during these peaks. Where there are more repetitive peaks of longer duration the supply sags, bigger caps provide a longer time constant so that more repetitive peaks can be handled without clipping and there will be less 60/50 Hz ripple. It really does make a difference and even many years ago Dynaco sold an add on capacitor box for the ST400, I think it was 100,000 uF.
It is always interesting to think of things at the limit, if we think about infinite caps the supply would never sag and then the RMS continuous rating of the amp then becomes equal to the dynamic headroom value, it would also have no ripple. This is similar to a regulated supply.
Here are some quick calculations for a typical 50W example, assuming that the output stage comes within 2 Volts of the rails and does not current limit:
Hmm, this table gets ruined by the forum software, moderators can I inline HTML here or how is it done?
Idle, Full power 8 ohm, Full Power 4 ohm
V+/- , 40 V, 30 V, 27
Vpeak out , 38, 28, 25 = V+/- - 2
Vrms out, 26.9, 19.8, 17.7 = Vpeak out *.707
8 ohm power, 90 W, 49 W, N/A = Vrms out^2/8
4 ohm power, 180 W, N/A, 78 W =Vrms out^2/4
You ask good questions Beppe.
Pete B.
| quote: | Originally posted by beppe61
Dear Sirs,
I have bought a 30 years old integrated amp.
How can I assess if the capacitors (originals) must be replaced?
Aestetichally they appear in good shape.
There is no form of leakage or other.
They are SPRAGUE 36DX and rated 7200 uF /50 VDC.
There is also a serial number 7552.C.
Thank you so much.
Kind regards,
beppe61 |
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| PB2 |
Let me add:
The power at idle is what the amp will put out for short peaks without clipping and so we can compute the dynamic headroom:
8 ohm dynamic headroom = 10 log (90/49) = 2.64 dB
4 ohm dynamic headroom = 10 log (180/78) = 3.6 dB
Also note that with infinite caps the RMS continuous output would be 90W into 8 ohms and 180 W into 4 ohms. You can see what happens as you make the caps bigger.
Increasing the caps by 4X usually makes a significant difference, but as others have said you have to watch inrush current on the bridge and power switch.
A transformer on the small side (cheap) with higher internal resistance will naturally limit inrush current.
Pete B. |
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| jacco vermeulen |
| quote: | Originally posted by beppe61
If I seem too much enthusiastic about this simple "operation" just think this is my very first time ! |
Beppe,
there are plenty of people on this forum who recognise this from memory.
Replacing 30 year old capacitors that must have dried out considerably by new ones, which are bigger and faster, should make quite a difference.
Going for Rifa's instead of Sikorels was a good choice, remember that construction of Rifa's is unlike other capacitors. Rifa capacitors contain a liquid, and have to be placed standing upright because of the pressure relieve valve on the top. |
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| beppe61 |
Dear Pete,
thank you greatly for your extremely kind and valuable reply.
>| quote: | Originally posted by PB2
Hi beppe61 hope things are good with you,
I'm a bit late here but I wanted to mention a few things. Numbers like 7552 are typically date codes. The cap was manufactured in the 52 week of 1975 which agrees with your comment of 30 years old.
Thank you very much. Very very interesting knowing about the production date.
What can you tell me about the shelf life for NOS caps?
I read is quite long.
The old caps do not leak but with them installed the sound was less strong, less definite.
> A power amp with unregulated supplies, lets say something like 50W/ch, will idle with about +/- 40 V on the power supply. If you load it with a dummy load and drive it to clipping on a bench, the supply will sag typically to about +/- 30V for this type of amp and more 60/50 Hz ripple will be present.
Now remember that power = V^2/R so if the supply stayed at +/-40 it would be able to deliver much more power, and indeed this is where the dynamic headroom comes from.
The supply does not sag much during short peaks in the music and the amp can deliver more power during these peaks.
Where there are more repetitive peaks of longer duration the supply sags, bigger caps provide a longer time constant so that more repetitive peaks can be handled without clipping and there will be less 60/50 Hz ripple.
You have given me a lecture on caps ! very very good indeed.
Now I have something to study very deeply.
I must tell you that these things (caps) are intriguing me very much. They are power reservoirs in the end.
> It really does make a difference and even many years ago Dynaco sold an add on capacitor box for the ST400, I think it was 100,000 uF.
WOWW !!!! 100.000uF is an awful lot. Are they really needed?
What kind of amp (power rating) this Dynaco was?
was the caps box connected by an umbilical extension cable?
how long this cable can be at maximum? this option is very very interesting to me indeed. I am thinking about it.
> It is always interesting to think of things at the limit, if we think about infinite caps the supply would never sag and then the RMS continuous rating of the amp then becomes equal to the dynamic headroom value, it would also have no ripple.
This is similar to a regulated supply.
I understand this quite clearly.
> Here are some quick calculations for a typical 50W example, assuming that the output stage comes within 2 Volts of the rails and does not current limit:
Hmm, this table gets ruined by the forum software, moderators can I inline HTML here or how is it done?
Idle, Full power 8 ohm, Full Power 4 ohm
V+/- , 40 V, 30 V, 27
Vpeak out , 38, 28, 25 = V+/- - 2
Vrms out, 26.9, 19.8, 17.7 = Vpeak out *.707
8 ohm power, 90 W, 49 W, N/A = Vrms out^2/8
4 ohm power, 180 W, N/A, 78 W =Vrms out^2/4
Thank you so much for this extremely interesting calculations.
> You ask good questions Beppe.
Pete B.
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I strongly wanted to try to understand something on the topic of PS for audio amp.
Now I have to wait at least two week for some burn-in effects.
I promis to report again after that.
Dear Pete,
thank you so much for your extremely kind, friendly and valuable advice.
I wish you all the best,
beppe61
Italy |
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| beppe61 |
| quote: | Originally posted by jacco vermeulen
Beppe, there are plenty of people on this forum who recognise this from memory.
Dear Jacco,
thank you very much for your extremely kidn and valuable reply.
I have to tell you that at school I preferred labs rather than books.
I am an experimental kind of guy.
Unfortunately I am not so good at theory that I think it is always the base of knowledge.
> Replacing 30 year old capacitors that must have dried out considerably by new ones, which are bigger and faster, should make quite a difference.
One thing I have understood, Not all caps are equal in performance.
The speed in charging and discharging I understand is critical for a dynamic sound.
> Going for Rifa's instead of Sikorels was a good choice,
tha Sikorel are in a box waiting to be used.
I read great things about them.
But due to their dimensions I have to pull out the transfromer from the chassis to make space for them.
Maybe in the future. Now I want to assess the quality of these Rifa.
> remember that construction of Rifa's is unlike other capacitors. Rifa capacitors contain a liquid, and have to be placed standing upright because of the pressure relieve valve on the top. |
THANK YOU VERY MUCH FOR THIS VERY IMPORTANT NOTICE.
So I have to put my amp upwards because the screws are in the lower part of the chassis (or rewire everything. A possibility).
On the basis of the first listenings I am quite optimistic about the result. Really.
I will let you know.
Thank you so much again.
Kind regards,
beppe61 |
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| beppe61 |
Dear Friends,
just an update after having installed 2 new 10.000uF/63V Rifa PEH 200 in my amp.
These caps are really good.
I can safely say that:
1) the bass has gained definition and power
2) the transparency has increased evidently
3) the noise has lowered (I can hear more things, if you know what I mean).
A nice improvement over my 30 years old Sprague caps.
A side note.
I understand that the high-end brand Gamut uses white Rifa caps in its power amps.
I heard that the Gamut sound is very remarkable indeed.
Food for thought.
To end, I think that these Rifa caps can be safely recommended for high quality power amps PS.
Thank you everyone for your extremely kind, friendly and valuable advice.
Kind regards,
beppe61 |
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| peranders |
| Beppe, a friendly hint: Avoid quoting, do it only when the reader might wonder which post you are referring to and if you really do qoute, take only the interesting part of the text. Much easier to read you see. :idea: |
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| beppe61 |
Dear Mr. Peranders,
thank you so much for your extremely kind and friendly advice.
The problem is that I get replies with 3 or 4 statements different for content and I would like to reply to each statement separately.
And I have not yet worked out how to do it.
May be I can quote just the beginning of the sentence ?
I understand perfectly well your point, anyway, I am sorry for this.
Besides as I understand that you are from Sweden and Rifa is a Swedish company, what do you think of their caps?
What is you brand of choice when speaking of filter caps for power supply (I mean those big ones for power amps).
Thank you very much indeed.
Kind regards,
beppe61 |
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