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Caps and Tubes

My pre-amp is an Audio Research LS-16. It was more or less inherited. It is the only pre-amp I have ever owned.

Looking down into it through the screen on top there are four large capacitors that say "Wonder InfiniCap". There are some numeric specs on them as well.

I'm wondering if these were original to the unit or added later as an upgrade. It has four fairly large tubes. They do not appear to have anything written on them that I can see. I'm wondering how to know if these are the original tubes.

This is all academic since there is little or no chance that I'd hear much difference between different types of caps and tubes but I'd still like to know if they were original or not. Of course if no one knows I can contact AR.

Thanks,

George
n80
erik_squires
16,558 posts
 
Film caps don't age like electrolytic caps do, especially if used well below spec of voltage and temp, so no age reason to change them.

Unless the OP has a sonic issue with them or a lot of money to spare I would discourage cap rolling here.


atmasphere's avatar
atmasphere
12,070 posts
 
You might want to get the filter capacitors replaced. These are not the film caps that have been mentioned so far.
The filter capacitors are electrolytic and after a couple of decades they are often failing. It is possible for their failure to also damage the power transformer, so its a good idea to replace them.
djones51
4,947 posts
 
Audio research has a database of old equipment at arcdb.ws you can look up yours under line stage. It gives a little info on the unit and has a photo of the interior so you can see it better without taking the cover off. The wonder caps look original doesn’t look like the tubes are soldered. Perhaps you have already been to the site if so you can ignore this post.
tubegb's avatar
tubegb
198 posts
 
George,

 

This subject has been pretty well covered, so just additional affirmation from a former ARC LS16 owner:

 

  1. The Wonder InfiniCaps™ are definitely stock.
  2. The ARC Database is a wonderful reference tool but know it is not in any way affiliated with the Audio Research Corporation.
  3. If you plan on keeping your LS16 for a while then another vote for atmasphere’s (always) sage advice. Have the filter capacitors replaced and consider it preventative maintenance.
  4. Although not brought up, if you go looking for a phono preamplifier the ARC PH3 made an excellent and very synergistic combination with the LS16. The PH3 utilizes three 6922’s, same tube as your LS16.

soundermn's avatar
soundermn
344 posts
 
To answer your question on replacing tubes... they simply pull out and you can replace them by gently pushing new ones in.  Give them a little wiggle as you pull gently, and they should come right out.

If one fails, you don't need to replace all 4, but if you don't then you'll have a mismatch.  The new one will operate at a higher level than the old one.  You may or may not notice.  I would replace in matched pairs, at least.  

If it sounds fine, I would wait until one fails.  You never know... the system may have only had a few hundred hours of use, and the tubes should last thousands of hours.  Don't replace them just because they are old... you may end up spending money for nice NOS tubes when you already own good, usable vintage tubes.  
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