Original Cary 300B Monos Reliability?

I don't really know but Cary has made those amps for a long time and I have never heard anyone say they are problematic. Generally speaking some people have trouble with tube amps and other amps by mismatching and over-driving the product. I don't think they are inherently not reliable. Remember some people drive tubes hard even when they have heard a sonic issue and ignore it. That will stress a lot of amps. Keep an eye on bias and don't try to blow them up and you'll be good.  

Check and adjust bias on the 300B when replacing it and periodically thereafter.

Agree with @russ69 , these are very straightforward well designed amplifiers that have successfully withstood the test of time. One of the primary assets of SET is their simpler circuit and relatively low part count. The Cary 300b SET would not have its establhed longevity/reliability  it they were built cheaply or poorly implemented.

Charles

Thanks all, for offering your feedback. I understand schematics, but I'm not good at all with the math for circuit design. The discussion centered around too much capacitance after the rectifier, and they also thought the 300B was run quite hard. Many who chimed in "knew" that Cary had made dubious circuit decisions through the years. I was just looking for any real-world issues with former owners of the first iteration of the monos.

Charles, I was hoping you would check in. You weighed in on my Cary/ProAc questions a little while back. I have an Audible Illusions M3B lined up to borrow when I get the Carys, so I'll be duplicating a system I heard so many years ago. 

I really like my CJ CAV45 S2, but I still want a little more of the reach out and touch them midrange that I recall from the Carys. I'm closing in on a deal for a nice original pair with the additional 14 capacitor bank - just have to work out shipping for three boxes $$$. I also acquired a pair of Response 2 speakers, so I'm ready to get this going!

Will let you know when things come together.

The Response 2's are exceptional speakers. Very holographic.

Good luck.

@leahy

I really like my CJ CAV45 S2, but I still want a little more of the reach out and touch them midrange that I recall from the Carys. 

I do not doubt  that  your CJ CAV 45 amplifier is serving you very well.  However the "reach out and touch " tactile quaility you're seeking is in my experience a true strength of good quality output SET amplification. 

As good as my  previous push pull amplifiers were, my Coincident Frankenstein 300b SET just took this characteristic to an upper level.  I'm curious to see how this plays out in your audio system given the inevitable variables and the Spector of component/system synergy. 

Charles 

Update: somewhat disappointed with the Cary monos/ProAc R2 combo, BUT, my 16 ohm single driver speakers (Finale Audio: Vivace Mini) are an excellent match. I'm missing a little bit of the mid-bass weight from my JBL L112 along with ultimate volume. For most daily listening, these Cary's are just what I was looking for. 

I am looking to max out the 6SL7 and 300B tube options. I'm thinking new WE 300B ($1,500!!!) and some nice NOS 6SL7 tubes. Any thoughts on these options would be appreciated.

Charles, what's your preamp with the Coincidents?

@leahy 

Congratulations with the Cary SET and Finale Audio speaker pairing. I use the Coincident Statement Line stage (101D tubes). You are wise to consider the upper tier quality 300b tube such as Western Electric. I'd also recommend you consider EML XLS and the Elrog 300b as well.  There are very good word of mouth reports  in regard to the Lanlai Elite 300b tubes.

Charles

@leahy For many years I ran a Cary CAD-301SE (a little-known model) with ProAc Response 2.5’s. I used the first reissue WE300B’s that came out in perhaps the 1990s--not originals, and not the new ones. I found the combination excellent. It didn’t plumb the bass (just as much the ProAc’s "fault" as the Cary’s), but with the midrange it provided it was easy to forgive.

Here’s one of the few photos I’ve found of a 301.

Charles - I found the information regarding concerns with the Carys running the 300Bs near their limits. It came from the EML web page. They suggested the XLS as a best option for Cary. Those tubes may draw more amperage, so I would check with Cary to confirm that the power supply will have no issue. Might also be a question about the base fitting into the tube cutout (a little on the lean side). I know the WE will fit and be a great tube, but I wouldn't mind paying a bit less.

Current preamp is a Croft 25 w/ phono. It's quite good without complaints, but other options might bump things up another notch.

Two-Left - thanks for taking the time to reply. I won't go wrong if I get the WE, especially based on your experience. If they last 10-15 years, it will be a great investment!

@leahy Hopefully you won't have issues with the Cary monoblocks, While I can't speak to those exact amps, I did run SLM 100 monoblocks back in the day. The Jentzen coupling caps Dennis was using at the time were known to leak, sure that's been addressed in yours. I applied diy repair here. I also had issues with bias circuit, don't recall the exact issue as I sent in for repairs.

As far as running power tubes hard, not all that unusual. Between running higher voltages in the amps and lesser quality of many new tubes, failures happen. I'd stick with the EML XLS or Western Electric 300B's in more difficult amps.

Thanks SNS. I need to look into biasing the monos.

I’m listening to "3 tube" Cary monobocks as I type. I run WE 300Bs and they are stunning. The WE tube was what Cary originally supplied in the amps. Your concern about XLS fitment is well taken. I had a pair of KR 300BXLS and they would not physically fit into the chassis; the openings are too small.

The KR 300B XLS was offered by Cary as a separate model monoblock in the day, not as an optional tube. I suspect there is a reason and I strongly suggest you check with Steve at Cary before you run XLS tubes based on other’s opinions. As my amps are auto bias, I am more than happy to run Western Electrics since they were OEM.

As far as reliability, these are 1999 vintage, had the original tubes until last year and have had no service. Eventually caps will dry out, but I suspect alleged reliability issues may come from people suggesting the use of tubes Cary did not recommend. Equipment can be fussy about which 300B tubes are used. I have a preamp whose maker told me to use Electro Harmonix as supplied, no exceptions and no warranty otherwise. Another integrated of mine with auto bias tried to red plate a set of WE 300Bs, but is perfectly happy with KR tubes. My point is no one cares about the price of a signal tube, but if you are paying $750 per tube, you may want to ask the people who designed, built and service your equipment rather than people who tell you their tube will work "just fine."

I’d certainly agree that it’s wise to check with the manufacturer regarding approved and compatible tubes for use in their amplifiers. If for Cary the W.E. 300b is the recommended or safer choice then so be it. By many indications it’s an excellent current production 300b.

The EML XLS has been nothing short of truly brilliant in my Coincident SET mono blocks. But surely better safe than sorry.

Charles 

MW - sage advice. I’ll be ordering some WEs!

@leahy 

I don’t believe that you can go wrong with that purchase. I’m interested in your listening impressions of the Western Electric 300b.

Charles