LP 275M No Output

[SolderSlinger]

Hello Roberto,

LOL

The question is "did you try here?" If you had you would know that the available resistors are actually Dale products. Do a search on metal foil, and bulk metal foil.

Best regards,
Jeff

[awise1961]

As a relatively new LP275M owner (approx 1 year), I have been following this thread intently.
Solderslinger, I believe that you and AJ know my pair of LP275's quite well.
I must say that I consider myself very fortunate in that other than changing out the 6922 tubes to NOS Siemens CCA's, my pair have been totally reliable and drive my Wilson Alexias wonderfully. I have not, and do not, experience any hum whatsoever.

[SolderSlinger]

Roberto.....are you trolling me just to keep this thread alive? LOL
The link is also to the wrong part. I don't remember the part model number. However if you look at an older Premier 12 schematic some of the front end resistors are Vishay bulk metal foil. Something like MMF-52 or 55. My example is not correct, but that is what you want to find. Then do a search on it. You will find that Vishay offers an almost endless combination of customization for metal foil resistors. Without knowing the CJ part number you're shooting in the dark finding an exact replacement part.

Now to pick on you, but you've basically proven why CJ will not service equipment that someone else has tampered with. Who knows what someone has substituted in.

I am a DIY-er. I would rather fix something myself. I understand why people get upset that they have to return CJ gear for repair. But I fully agree with Jeff's position. I don't want to buy equipment that has been repaired with lesser (inferior) parts.

[SolderSlinger]

@homey68

What did you end up doing with your amps? There's a pair listed on Audio Mart. Is that your pair?

[microstrip]

I am a long time owner of conrad johnson equipment - in fact one the first persons to get CJ in my country, at that time trough the UK distributor Audiofreaks. MV50, MV52, MV125, Premier 12 , Premier 8, LP255m and ART amplifiers, PV10, PV9, PV11, PV12, premier 7, premier 14, ART , ACT2 , CT5 , GAT and GAT2 - all stayed in my system, giving me great enjoyment along the years. A few in the list are actual residents, I should add the excellent sounding solid state premier 350 to the list.

Living far from the US, reliability and service were always a concern in my acquisitions - any problem would result in trouble with customs, delays and large shipping charges. Besides, in high-end I have always tried to follow Robert de Niro advice to Natascha McElhone in Ronin: "Lady, I never walk into a place I don't know how to walk out of". I say -I never get anything that I can't service myself or get efficiently serviced. The high-end is is an hobby for enjoyment, not a torture or a punishment. Long experience with audio electronics DIY and knowledge of electronic engineering and instrumentation also helped and were part of the hobby.

CJ was one of my choices is this hobby because it fulfilled my terms. With a few exceptions surely - every high-end manufacturer has them - conrad johnson equipment is intrinsically reliable - safe designs, excellent quality components, mechanically robust and good quality of assembly. However, any tube equipment is as reliable as the quality of the tubes we put in operation in the device - and the majority of the tubes easily available on the market are not adequate to cj circuits for several technical reasons. I will go through two of them . CJ operates many of their amplifiers at 60 mA output current, more than 500V anode voltage and uses RC grid coupling with an high value resistor. We need good tubes with low grid leakage current that can accept this high current and high anode voltage - many can't. The less known aspect is that CJ often uses double triodes with both sections connected in parallel. In order to accept this mode of operation a tube must have "balanced triodes" - this means that both triodes in a tube must have similar DC parameters. Otherwise, the current that enters in the triode will not split equally between them and will go mainly through one of them, that heats more than expected, carries even more current due to heat, and after reduced time in this positive feedback scheme becomes noisy or faulty.

Using tubes selected for these aspects I had zero problems with CJ equipemnt when using tubes tested and burned in my DIY built jig. The few times I had trouble in the past - some transistors in the power supply regulators of the PV9 -Lew Johnson kindly send them to me. I must recognize that the fault was mine - in a session of tube rolling with friends I risked a very special non tested tube some one has brought in my preamplfier and found that it had an internal short circuit.

I have however helped friends who had trouble with their cj equipment - with the help of CJ existing schematics, that keep the basic design and functional aspects along the years it was a simple job.

Now back to the LP275m - it is an extremely reliable, simple and well protected amplifier. To the point that, as I own other brands of equipment (VTL and ARC) that I use them for 6550, KT88 and KT120 burnin - I always burnin tubes for 100 hours and re-measure them before being put officially in service. Surely this costed me a few KTK2 fuses and a couple of 20 ohm cathode resistors - easy to source if we know where to look for and have a technical, not too imaginative mind. Using the available circuit in this forum and a multimeter the LP275m is extremely easy to diagnose, even without opening it. In my opinion CJ become easier to service along the years, contrary to the general trend in high-end equipment, that become more complex.

Just my findings and my opinion - surely some people will have different views or disagree. But along the years cj have brought me great enjoyment and many members of this forum helped increasing my knowledge and respect for this fabulous brand, my time to contribute.

BTW1, some people here will probably have remarked I am selling a pair of LP275's in audiomarkt - the only reason is that I got a pair of ART amplifiers and the LP275s are now idling - I am now listening to the ART's.

BTW2 - I still regret having sold my ART series III cheap. It was before I learned about the PCC88 ...

[Big Dog RJ]

Ah! Good one MS, and welcome to this forum CJO!

Agree on all your points... and just to add, going through your post, for a minute I though it was written by my long term trusted CJ techie. But it was you! And CJ techie says the exact same thing! So a mighty WOOF to that!

Same situation here, Down Unda, although we do have our long term CJ importer / dealer in Aus, from whom I've bought every CJ gear from, other than my prior years living in other countries, this highly skilled group of tube techies are getting old now. So, as far as I can send my gear to these trusted chaps for service, I'll continue to use CJ tube gear for long as possible. Until they call it quits. Sadly, this kind of breed is becoming extinct here, no one bothers to fix or service anything.

OTOH, McIntosh and Pass Labs are going full tilt Down Unda... plenty of sales and solid service centres, a well established business model. However, those brands don't fully engage me in musical bliss... so until such time it's tubes a-glowing! Pass Labs is currently on my short list for a SS alternative. Then again nothing can really be an alternative to tubes, and for that matter especially CJ. Based on Class A circuits and very high grade parts, these gems are not ordinary tube gear. Extremely extraordinary and quite simple in circuitry.

Oh, for the love of tooobs.
Cheers matey, and do enjoy those finest tunes.
Woof! RJ

[homey68]

Turned out to simply be one of the 6922 tubes shorted. Without a tester, I had a hard time finding it.

[admin]

Very nice. Quick and inexpensive fix!

[homey68]

The amps are for sale on USAM with or without the tubes. Selling off my system due to health problems.