Question For Those In The Know About Audio Research Power Amps

First, I'm pretty certain that the factory warranty for REF 110 amps is long past. 

Second, this is a clear example of us needing to do our homework before purchasing.  a quick initial inquiry to Audio Research before purchasing would tell one whether a REF 110 amp was offered as an SE model.  It also would address the use of KT150 tubes.

Third, most Audio Research amps were not designed to accommodate KT150 Tubes.  This has absolutely nothing to do with allowing customers to tube roll.  It had to do with some pretty extensive modifications to equipment to allow for the extra power handling capabilities of KT150 tubes.  Transformer upgrades are one thing that the REF250 amps required among other things.

Since KT150 tubes didn't exist at the time the original amp was designed/built, it is hard to blame Engineers for not allowing for the amp to be used with KT150 tubes.  You design around certain parameters. It can't be open ended designs.

The REF 110 amp in and of itself is a very nice amp, even to today's standards.  If Audio Research tells you that it is okay to use KT150 tubes in it, that is great.  However, I do have an issue with the "dealer" telling you that it was upgraded to SE status.  Since upgrading to SE status for most Audio Research Amps took way more than just changing tubes.

Enjoy

@fsonicsmith response it very telling.  ARC goes through many tubes in order to produce "matched" tubes.  they probably re-sell they non passing tubes to other's.  however, that says a lot about Audio Research and their level of expected excellence.

I made the mistake of purchasing tubes for my REF 250 amps from a "reputable" tube supplier in Southern California.  They claimed that the tubes were matched and to specifications for the REF 250 amps.  Not cheap, but much less than what Audio Research sells them for.

Well, approximately $3000 in repairs later, I learned my lesson.  Tubes failed after they were correctly biased.  I was sitting there and actually saw the tube go up spectacularly and the circuit board.  It took out other parts of the circuit, not just resistors.  It costs $3000 to repair. 

If I had purchased the tubes from Audio Research directly, they would have repaired the amp free of charge if their supplied tubes caused the failure.

The authorized Audio Research repair center that did the repair work, told me to never purchase tubes from that supplier as although they claim that they are matched and to specification, they are not.  They proceeded to test all the remaining tubes and showed me the readings vs Audio Research's standards for that amp.  These brand new tubes weren't even close.  They were way outside the acceptable range. Also, when the tubes arrived, they listed clearly on the labels what the specs were.  That is so wrong.

I never contacted that tube supplier, because, what is the point?  If anything they would have replaced that one tube.  But no way would they have repaired the amp.

When I repair solid state amps and I have to purchase transistors, I typically have to purchase many just to find matching ones and also ones to match the "good ones" still in the amp.  Often, I just replace all the transistors, just to be safe.

So, I can see why the costs of tubes from Audio Research is so much higher.

enjoy

Yep, that is the case for KT150 tubes.  I imagine that one could use KT88, KT90, KT120 tubes instead if you desire and they fit the sockets.  You would have to know the new bias points.  But, a simple call to Audio Research would confirm this. 

Audio Research equipment was modified to accept KT150 tubes, this meant upgraded transformers to hand to power handling/draw capabilities of the KT150 tubes.  If they can handle KT150 tubes, they can definitely handle tubes that came before with lower draw characteristics.

But as I mentioned earlier, since most manufacturers can't possibly know what new technology or tubes will be produced in the far future, it is impossible to design for them that far in advance.  You design for what you know now.

If you can find an alternate tube supplier that will supply matched tubes within Audio Research's specifications for that amp, for a lower price, well,, go for it. 

I can tube roll to my hearts content with my REF 250 amps and my REF6 pre-amp and REF 2SE phono stage, up to the current level of tubes that they can handle.  'For my REF250 amps, I just can't go above KT120 level.  not big deal.

its like with supercars or Mercedes or high end cars.  The maintenance costs is very high. People find themselves in hot water when they purchase something without investigating the maintenance costs first. 

That is a serious shock when the bill comes.  not a big deal with pre-amps or tubed phono stages, but for large powerful tubed power amps,  This could be a down payment for a new car replacing the tubes.  

thinks the REF 150 tube replacement is bad?  or my REF 250?  Look into tube replacement for a REF 610 or 750 amp.  or other manufacturers that make large tubed power amps.  Tube replacement costs is no joke.

not for the faint of heart.

enjoy