"Updaing" an integrated amplifier

Hi All,

I have an Atoll IN80se integrated amplifier that I wish to "refresh" few of it's electronic components and I would like to hear your suggestions and/or ideas:
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1. it's bridge rectifier is a monolithic 8A cheap looking bridge rectifier and I would like to replace it with a better quality 25A one, prefer to stay with monolithic type and not using separate diodes, any suggestions for a good quality monolithic bridge rectifier?

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2. would like to replace the 4x 6,800uF 63V Jamicon (marked green) main capacitors with 10,000uF or a bit higher value ones, restricted to 30mm diameter and 50mm height, was looking for a KEMET ALC10S series or Kendeil K05 but couldn't find any in stock (online) the only one I could find is the Cornell Dublier SLPX series, is it good for this purpose? do you know any other better capacitor that will fit? looking to spend about 10Euros each.


3. I would like to change the 1uF input capacitors (currently cheap MKP, marked red) with a highr quality one, looking to spend no more than about 12Euros for each.


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4. Change the cheap 10x Jamicon 220uF 63V capacitors (marked yellow)next to the TIP31C bipolar transistors for a higher quality ones, any suggestions for better capacitors?


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I'll appreciate any suggestion, idea or comment.
Thanks
 

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The MKP look okay, so does the rectifier.
A 10 amp bridge from a reputed make should be enough. 25 may need manipulation to fit.
Don't be fooled by people telling you to put Schottky diodes or exotic capacitors, mostly snake oil stuff, designed to loot you. That goes for op amps too.

Put any Japanese, Wilma, Vishay, Taicon, Sprague capacitor as a replacement for those you think would be needed, try for 105 degree rated ones.
First get them on your table before starting, all sorts of weird shortages exist.
If you know anybody in India, get Keltron as an alternate, they are Sprague licensed, very good.
 
Oh, and try to put MOVs on all the relay outputs, and spray the insides with contact cleaner, they are a source of noise, and sometimes hard to get.
MOVs will protect the contacts, they work as arc quenchers in this application.

Order good relays to keep as spare if you feel like, they are going obsolete / bonkers lead times also, and you will save some money on shipping and handling for a combined order.
Omron are good, and there are other reputed makes also.
 

as_audio

Member
2008-05-13 6:18 pm
The best you can do is sell the amp immediately, it is a nightmare.

Second best is mount the output devices on a bar or heat sink coupled
to the bottom of the case.

As you see there are essentially no sinks for these transistors and consequently
bias is set to a ridiculous value.
 
The best you can do is sell the amp immediately, it is a nightmare.

Second best is mount the output devices on a bar or heat sink coupled
to the bottom of the case.

As you see there are essentially no sinks for these transistors and consequently
bias is set to a ridiculous value.
My experience is very different from yours, I actually enjoy the amplifier very much, no over heating issues despite the small heatsinks and the bias is very stable at 8mv (5mv originally) and 0.3-4mv dc offset on both channels.
I was thinking about using 1 a bit larger heatsink for both of the output transistors on each channel for better heat coupling between the transistors, but again, no overheat issues and to be honest the Atoll is much cooler than my Cyrus 2 and Exposure 3010S.
....and sounds much better than the Cyrus and cleaner than the Exposure, and a lot better than any Cambridge Audio, Naim Nait XS, Marantz PM-66KI and Rotel that I had before (all RA-9XX series).
 
The MKP look okay, so does the rectifier.
A 10 amp bridge from a reputed make should be enough. 25 may need manipulation to fit.
Don't be fooled by people telling you to put Schottky diodes or exotic capacitors, mostly snake oil stuff, designed to loot you. That goes for op amps too.

Put any Japanese, Wilma, Vishay, Taicon, Sprague capacitor as a replacement for those you think would be needed, try for 105 degree rated ones.
First get them on your table before starting, all sorts of weird shortages exist.
If you know anybody in India, get Keltron as an alternate, they are Sprague licensed, very good.
Thanks.
There are no op amps in this integrated.
A little manipulation for larger(and hopfuly better) bridge rectifier is not an issue for me, not looking for Schottky diodes or anything alike just better quality monolithic rectifier with a little higher A rating than the 8A currently installed.
Any suggestions for PSU capacitors (30mmDia x 50mm height)?
 

as_audio

Member
2008-05-13 6:18 pm
My experience is very different from yours, I actually enjoy the amplifier very much, no over heating issues despite the small heatsinks and the bias is very stable at 8mv (5mv originally) and 0.3-4mv dc offset on both channels.
...
So it seems the amp works to your satisfaction.

My precautions for repair clients are:
  • avoid to let it run all the time or over night,
  • no party, no extended sessions,
  • no low impedance speakers, better 8 or even 16 ohms,
  • no obstruction of free air flow above and around the amp.

Bias is extremely low for the reason described and crossover
distortion can easily be detected when the amp just started cold.
 
If you do greatly increase the rail capacitance, then yes, consider a larger rectifier. Form-fit may be difficult.
How big? Do the calculations. Inrush can be amazingly high. Unless you are at least doubling the capacitance, you will not notice any differences. I was suppressed when I put my old Creek 4330 on the bench and the caps were good as new. Do you hear hum?

Series of caps is not really as important as WEB aufiofools say. Pick long life from one of the major brands. I just used some Panasonics in my old MOSFET0 Do watch out for caps sold on e-bay with the manufacture or series marked out. I do not know the Continental suppliers, but over here, Mouser, Allied and Digi-Key are my only sources.

My experience is Atoll are quite nice as shipped regardless of what one person seems to think by looking at a picture.

I doubt the smaller caps are a problem at all. Why do you think different input caps will help? If polycarb, maybe polypro is better on the bench, but audible? Questionable.

It looks like your relays are sealed, so unless you choose to replace them, no worries. They are a "maintenance" item. Your choice.

Unless you are hearing hum, you might best just listen and enjoy.
 

Rallyfinnen

Member
2017-01-22 10:18 am
Sounds to me that the best upgrade would be a proper heat sink and optimum bias, that would yield some actual improvement in (distortion) performance and reliability.
All the other stuff is secondary IMHO..
I have seen the same kind of issues in a few other budget amps where they saved money in the wrong places.
 

Galu

Member
2018-04-17 6:50 pm
As the old saying goes: "If it ain't broke, don't fix it"!

Satisfy your modding and DIY urges by working on an old or 'vintage' discrete component integrated amplifier.

If other forum members are like me, they will have at least one lying about unused that they would be willing to donate to such a good cause!
 
Thank you all, Don't get me wrong, the amplifier sounds very good (pushing my Dynaudio Focus 110 or the Polk Audio S20e) and nothing is wrong with it, it's just the modding bug and the DIY spirit in me (-:
Then don´t "solve" non existing problems.

Mod whatever needs to be modded (or repaired/updated) as suggested above, not this one.

And forgive me but recapping does not qualify as DIY.

Actually build something, anything you like/need/desire.
 
As I replied to someone else in similar thread
The only thing that I did was to put two new RCAs, two 2.2 uF film caps, and cables to new binding posts. And, oh yes, another preamp unit!
Which is to separate or isolate the amplifier from the preamplifier... Often the amp is high sensitivity so just a (electronic ladder) volume control & selector, which is again a solid state... errr relay controlled
Edit. I see a motor.. :geek:
 
Thanks for anyone who replied, I appreciate it.
…but I wasn’t asking IF I should do any modifications on this amplifier or not, there is nothing wrong with this amplifier “as is” and I’m not doing it because I need to do it, I’m doing it because I want to do it.
So please if you don’t have any suggestions related to my first post questions please don’t comment , thanks.
 
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huggygood

Member
Paid Member
2011-03-19 8:42 am
france (bretagne)
I repaired and do preventive maintenance on many Atoll amps and I know them pretty well.
The important parts to change are the small capacitors in the center of the PCB and those next to the timer/protection relay.
Redo and/or check all the welds.
You can replace the two MKPs with better quality models if you want but I'm not sure that on this amp it makes a big difference.
You will have to disassemble the main PCB to be able to work on it, it is painful but simple to do, on the other hand be careful when you resolder the capacitors and do not try to push their capacity (except those of power supply which you can pass to 10000 but the same, it won't change much, the power supply transformer is very well sized on this amp) on the other hand, replace them all with 105°C grades, especially the small ones.
For the diode bridge, I've never seen one break at Atoll, but if you feel better with a bridge that passes more current and voltage, it can't hurt.
 
I don't like Jamicon capacitors - too many early failures IME and poor specs to start with. It is also quite common for me to find Cornell Dublier capacitors in very poor condition in old amplifiers. I would certainly increase the size of the power supply capacitors to the largest value that will fit, and/or consider adding additional capacitance off-board. Nichicon LLS1J103M will fit, and Kemet and Rubycon also have good quality 10,000µF / 63V in 30ø x 50 package.

The outer appearance of a component is no meaningful indicator of quality or functionality, however the bridge at 8A rating is an adequate size for the rating of the amplifier, and increasing the rating isn't going to do much of anything. X2 spec capacitors for the input is odd, more normal to see WIMA MK4 capacitors here, but maybe France doesn't have a suitable manufacturer of audio grade capacitors. Personally I wouldn't spend more that about €1 on them and I'd spend the savings on something that makes a difference, but if you get satisfaction from spending €12 on input capacitors then go for it - it's your money!