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We're all in agreement that recapping is good, right? AU-D11

My opinion , coming from my 47 years old ears with my new speakers in my listening space with a passive crossover “A-B ing”.. actually the correct way to have a better opinion of the test should be A-B-A and testing 2 out of my 3 AU-X11 is that I heard no deference replacing electrolytic capacitors at values below 4.7uf with films.
Indeed recaping the unit made a big deference.
With my little experience, a circuit that the quality of the sound is depending in capacitors , it’s not a good circuit and this is not the case in most of the Sansuis , maybe it will make a hell of deference to a McIntoh unit !
If I’m chasing a better sound out of a Sansui circuit I learned that is better to spend my money , replacing resistors , transistors and YES JFETS rather looking for the super duper wow capacitor .
And the above goes for Sansui amplifier , other Sansui products I have a deferent opinion .
A kind reminder that using an oscilloscope, a troubleshooting device to identify if your unit is a “high end “ or a “hi-fi , you are simply fooling your self , that only your ears can tell you and your listening ability’s . If it was that so , then a single ended tube amp would be for the garbage’s….

I can go on for hours but I think I’m already out of the “subject line” and I’m sorry for that!
 
GrisPato said:
This is often true, sadly.
Some people on here I can discuss ( debate) the choices in components. Capacitors, resistors, transistors, etc. We share our opinions, our thoughts, without making our opinion more important or more true then the opinion and experience from others.
Just for example: I follow closely the restorations of Hyperion, leestereo, Bumpalump, argou, TupolevFan etc. We do not agree on enough parts of the restoration process. Some change everything to film, some even use foil resistors, change out every transistor they can find a replacement for, some keep everything as original as possible, some decide per case what they like to do, but I see an attitude of listening, sharing thoughts and enjoyment of the equipment. Furthering our combined knowledge and appreciation of the equipment we work on.
What I personally have a little problem with is that some opinions are shared as if they are facts. Like saying that the higher ESR of two electrolytic capacitors in series compared to a film capacitor will make the sound "warm and fuzzy".
Click to expand...
I also did not like "warm and fuzzy" label, but I think I understood the meaning, and I understand this point of view. I can sense when someone is deeply entrenched in his opinion (and believes science and common sense are on his side) and that is for me a signal to stop debating. It's somewhat like trying to say on turntable forum Microline stylus is not automatically superior to other stylus shapes. The forum dogmatics promptly jump on you and you either retreat or go into fierce debating. Fortunately, Sansui forum is not like that . :)
 
GrisPato said:
For the 907 MR they use two 2,2 uF in bipolar config ( 1,1 uF ) while they have 1 uF film capacitors in the power supply?!
Click to expand...
Everything is made for reason and i full trust sansui engineers

Main difference between electrolytic and film caps are:
Dissipation factor (lower for film caps)
dielectric absorption (also lower for film caps)
Both of them leads to some signal distortion, but distortion not allways mean something wrong (why some ppl love tubr amplifiers? Because of some harmonic distortion)

About the question why sansui used two back to back polar cap instead of one bipolar...
Its all about dc biasing ane distortion, two polar caps biased have lower distortion than bipolar without dc bias
Just like in CVC in crossover networks, mostly seen in high end JBL speakers

Search for: charge coupled crossover
 
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I always been intrigued why Sansui, Pioneer and Marantz designers used electrolytic in ""back to back" on some 70s models on their tone controls and I seen some strange distortion when replaced with film caps on some cases... I have no idea why, I'm too ignorant and my measurement equipment is kind of limited, so I don't worry too much about it a throw good quality electrolytic when I find that configuration when fixing old stuff. However I don't see that on modern equipment.

I do use film caps on input circuits and tone controls, they seem more linear. I use bipolars too when I'm the mood, and I use class 2 ceramics when replacing some other cap applications.
Is a subject that have nuances and people interested in to learn could learn some by reading books and experiment a little bit.

Chapter 2 on Small signal audio design of Douglas Self touch the subject and have the following references:

References
[1] D. Self, Ultra-low-noise amplifiers and granularity distortion, JAES (November 1987),
pp. 907–915.
[2] D. Self, Audio Power Amplifier Handbook, fifth ed, Focal Press, 2009, p. 43 (amp output
cap).
[3] C. Bateman, Capacitor sound? Parts 1–6, Electronics World (July 2002 to March 2003).
[4] D. Self, Audio Power Amplifier Design Handbook, fifth ed., Focal Press, 2009,
p. 205 (C0G cap).
[5] C. Bateman, Capacitor sound? Part 3, Electronics World (October 2002), p. 16, 18.
[6] C. Bateman, Capacitor sound? Part 4, Electronics World (November 2002) p. 47.

ttps://linearaudio.nl/sites/linearaudio.net/files/Bateman%20EW%2012%202002%20mar2003%201uF%20electrolytic%20or%20film.pdf

AES have some free papers about it.

Again, these a just some light readings to get into the subject and motivate people to grab their test gear a play a little, is not meant to convince anybody of anything.

So get some crappy caps, some good ones, make some filters, grab your scope and have fun people.
 
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If the unit uses standard casual capacitors, Yes
But if its equipped with custom caps like alpha series i wouldnt even think about recaping it.

Another thing is i never found a single worn out capacitor in alpha amplifier, an exception is C/B-2301 which udually need full recap, on the ither side i also didnt found a need to recap C/B 2105 or 2302
 
My little bit of sanity here. Blindly attacking every piece of gear with a soldering iron and a bag of caps probably will not generate desired results. On the other hand as many pieces are arriving at the 50 year old mark no matter how good the original electrolytic cap seals were they are getting close to end of life. I have taken time to measure hundreds and hundreds of removed caps with a pretty good esr/theta/uf tester, in fact have documented some of the results on the forum. Anyways, with my extensive collection spanning from 1968 to 1980 coupled with the above mentioned manufacturer trend to end radial/axial electrolytic cap production I have been going through them all and replacing caps as a long term collection activity. About done at this point so should be able to happily rotate those pieces in and out of the listening room for as long as I continue to enjoy the audio hobby.
Not going to get into the which cap is better argument, we each have our own ideas, a quick trip over to the Pioneer Tuning Fork booklets in the Pioneer forum will give one a good foundation, then off to Douglas Self's book as mentioned above. Might also look up many many discussions on this topic scattered all over the forum as the debate has been circulating since the forum began and even after two decades there is no consensus (but a lot of entertaining reading).
 
It must be the later Alpha's that have custom caps. The two first gen a907 I have, have normal audio caps in them. I also believe my C-2301 and B-2301 have normal audio caps.
Maybe the B-2301L has custom caps? I don't know yet. I've been trying to get one, but damn Sansui guys keep out bidding me!
 
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