• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Alesis RA-100 To recap or not to recap?

Marcel27

Marcel27

Active Member
Hi,

I have acquired a beautiful Alesis RA-100 studio reference amplifier with a wonderful sound. It probably dates from 1986, so it's around 40 years old. I am torn between whether or not to replace the capacitors. If I do, it will cost me around €50, bringing the total cost, including purchase, to around €95. I have read very good reviews of this device on the internet. The power supply capacitors still seem to be in good condition, but they are no longer available in this size. It seems that they are custom made. I have already re-soldered the connector connections on the circuit boards because I read that there are a lot of problems with them. No real hotspots can be detected; this amplifier stays as cool as can be.

Let me know what you think, I could use some advice.

Translated with DeepL.com (free version)
IMG_3350.jpg
IMG_3351.JPG



IMG_3354.JPG

IMG_3353.JPG

Alesis date.jpg
 
Register to hide this ad
Is it working fine? If so, I would just check a bunch of the smaller caps with an ESR meter to see if they are starting to go high. If all check good, leave it alone. If a bunch check high, start making a list.
 
Main filters of 10000uF/63V are readily avaiable...nothing special about them. But, they probably don't need changed out. If by size you mean the PHYSICAL size, yes, most modern caps are a bit smaller. If you decide to replace them, look for 12K to 15KuF 80V capacitors for two reasons:

Many modern caps are purposely underspecced but still within the -20%. So, a modern 12K cap might measure between 10-11K.
Not knowing what rail voltage the amp runs at, upgrading to 80V rated caps should = longer life, especially if 63V is barely adequate.
 
jheu02 said:
Main filters of 10000uF/63V are readily avaiable...nothing special about them. But, they probably don't need changed out. If by size you mean the PHYSICAL size, yes, most modern caps are a bit smaller. If you decide to replace them, look for 12K to 15KuF 80V capacitors for two reasons:

Many modern caps are purposely underspecced but still within the -20%. So, a modern 12K cap might measure between 10-11K.
Not knowing what rail voltage the amp runs at, upgrading to 80V rated caps should = longer life, especially if 63V is barely adequate.
Click to expand...
I agree with you that these big caps not need changed out. But the strange thing is that the physical cap size is bigger of the 10.000 uF/63V however they will still fit, old are 30x45 new are 35x50. I read that capacitors at room temperature can have a lifetime of 200.000 hours and even more even when they are specified wit 5000 hr at 105 C. The lifespan doubles every 10 C decrease. In an older project I swapped those big caps, but afterwards it was not necessary at. I tested them under full load in a new supply and they followed almost the specs. The value was still within the -20% range. They got a second life in my diy amp.

I'm awaiting an ESR meter next week so I will test the little ones and act accordingly @redk9258 advised. Thanks for you insight @jheu02.
 
I discovered that the mute fast function doesn't work for the right channel when I switch the amp off. In the beginning this function worked smoothly, but after a week it started with a big thumb in my left speaker and now also at the switch on. The amp wasn't played with for more than 4 years. I think the capacitors are now showing their worst side after playing for a while. The recap kit has been ordered.
 
You must log in or register to reply here.
Back
Top Bottom