CJ Solid State Amp Recommendations

[artoly]

From this description, I am thinking the gain is not an issue with my speakers, ARC Ref 3 and C/J Prem 350.

@artoly, when I look at some of the key specs (5.6db gain of the SE outputs of the ARC Ref 3, 1.1V input sensitivity of the Prem 350, 88db sensitivity of the Sapphires), your system seems, on paper, to be very well balanced. Hopefully, you can address the ground loop issue...and continue to enjoy the system.

Thank you for looking into that for me 33 rpm. Much appreciated and good to know. I am enjoying the system some more as I type.

[artoly]

I've ran into ground loop issues before and that certainly sounds like what you are dealing with here.

They can be fixed but it does take some experimentation, careful power connection layout, and a little bit of luck.

I have sometimes wondered if it is something for a technician to fix at the power supply in the preamp or power amp. Would you happen know if that is a path that some need to take to fix ground loops?

[artoly]

PS. For what it's worth, being 5 years late on this thread topic - My Prem 350 needs the correct voltage to run at the reasonable design temperature. Mine is rated at 220V and the wall voltage is around the 244V range (+/- at different times, being a bit over 10% difference). 244V is too much for my 350 and made it idle at about 55 degrees C over the fins (131F). After it died and I had it repaired (either from this or a spike, I'll never know), I added a big custom step-down transformer to achieve the correct 220V for the C/J. The idle temperature dropped to about 35C (95F) with this in place. The temperature does not increase very much in-use with my speakers and my volume levels.

I don’t know if there is an equivalent solution for voltages outside the US, but I was very pleased when I added the PS Audio power regenerators. My ARC gear manuals say their gear runs best at 117.5 Volts, and my experiments proved that my ears agree. Sadly, my various CJ amps were not compatible with the power regenerators, and CJ has told me that they do not recommend them.

FWIW, my Burmester gear likes 117.5 too, so even though I have two regenerators in my system, I’ve set them up to the same specifications.

Those PS Audio power regenerators look very serious indeed, being a very heavy 2 person lift for the 3600VA one. I am assuming a very big transformer in their, amongst lots of other good things. I wonder what CJ's concern is with them.

I bought a lower cost 5000W isolating transformer / power regenerator from a certain eastern country, but so-far-so-good with the CJ, plus the rest of the system that is all plugged into it. It has 2/220V outputs and 4/230V outputs as per my request and weighs about 27kg. My measurements under some load came in at 1-2V lower than the above, which seemed pretty good to my untrained understandings. I have the Prem 350, plus a Gustard DAC in the 220V sockets.

[Big Dog RJ]

G'day matey, seems like quite a journey there with the Prem350.

Yes, very good points made from our valued CJO members, they have vast experience across all types of gear, and most specifically CJ of course.

When it comes to proper set-up, there's no universal solution. Every system, room, power requirements and AC mains will vary depending on all sorts of parameters at yourlocation. Basically, you'll need to find the gear/ solution that works best for your particular system. As Admin pointed out, ground loops may creep in wherever possible, even though installation may have seemed straightforward. AJ has had very successful experience using PS Audio's regen gear, and seems to have proved very effective!

At the time I was living in a totally different country, our AC mains supply had terrible voltage fluctuations, apart from other unwanted nonsense on the mains. Tried various gizmo's from isolators to voltage stabilisers... nothing really worked significantly until I completely isolated the entire Audio rig onto a separate AC mains phase. Luckily that house (my dad's place) had 3 Phase AC mains, so after a few approvals from the Electricity Govt. Board, we were allowed to do this. That was a tricky project but it helped a great deal. Perhaps then, if I had tried one of those PS Audio regen units, maybe that would have been more feasible, rather than nearly demolishing half the house just to rewire things. But those units by PS Audio never existed back then... 88 - 98/99. Unfortunately, after 91, we had a massive flood! Our whole area went under and worst of all, termites started to creep in everywhere!!! They even ate a pair of my Maggie's! Eventually that house was sold and completely restored. It was very close to a famous stream that had quite a lot of other unwanted things floating in it... so wasn't really ideal for any highend audio installation. Constant power outtages, and voltage fluctuations, absolute nightmare!

Just reflecting on those former years back in Colombo, before the highend, we had various "other" gear from NAD, Musical Fidelity, Arcam, Marantz, Carver, Bose, Paradigm, Energy, Mordant Short, Polk Audio, B&W and so on... they just worked! Power would go out, all of a sudden thud dooof! Then come back on, thump! And tunes are playing! Wow! Fast fwd that to few years with highend audio gear, no chance Charlie! With highend gear, set-up is so damn fussy, slightest variations this way or that way... and it causes issues... hums, hiss, hiccups, burps and farts... oh bloody hell, just play the tooons! Sometimes I kid you not, I miss those days. Just turn the bloody amp on, pop in a disc, press play and listen to music! And sip a beer!

Anyway, sorry to digress... just thought it's so ironic all this fuss we go through in order to get the tooons to sound right.
Just take your time in finding the right type of application that would suit your specific system needs. Only you can determine which ones are the best, and arrive at a very quiet, low noise, distortion free playback system. Achieving zero noise is somewhat difficult, can be close to the upper 90% range with a few tweaks and the right type of application. It's a journey!

Also as correctly pointed out by our valued members, the specs look just about ok between your ARC preamp and the Prem350A... so technically based on your speakers efficiency ratings, things should work fine! I don't see any area where you would need to mod / adjust anything. However, as you've pointed out, setting up that beast of an amp, the Prem350 will take up quite a bit of current draw from AC mains. So getting its voltage requirement to match with your mains grid is definitely critical. In certain cases that we installed the Prem350 at other customers locations, based on their AC mains supply, they were able to get away with certain levels of tolerance between 1% or so but nothing higher. The moment those voltages shifted, things got out of hand. I remember back then, two customers locations just wouldn't accept the Prem350A, it would cause the CB's to trip off. Eventually, both settled for the older MF2300 series, worked fine!

I remember my CJ techie doing some work on a Prem350A, and whiles showing me its massive power supplies, he mentioned this circuit design is quite simple itself. No protection gizmo's at all, just a large fuse and that's it! If anything were to go wrong, kaboom is the result. The Prem350/A is a very straightforward design with quite a high Class A bias, which CJ doesn't divulge much. It's a formidable design and one hell of an extraordinary thing. The term "power amplifier" is actually an understatement! He referred to it as an "outrageous power amplifier!"

Yes, get that voltage requirement sorted out and try your best to eliminate that annoying hum .. once that's done, you'll be enjoying those finest tunes!
Cheers, RJ

[admin]

I've ran into ground loop issues before and that certainly sounds like what you are dealing with here.

They can be fixed but it does take some experimentation, careful power connection layout, and a little bit of luck.

I have sometimes wondered if it is something for a technician to fix at the power supply in the preamp or power amp. Would you happen know if that is a path that some need to take to fix ground loops?

No, I don't think it is due to faulty equipment (or at least 95% of the time it isn't).

First, I look for any potentially common noisy components. The classic is any component that connects to a coaxial cable (like cable television). Computers can also introduce ground loops. Look at components that may be connected via ethernet as those lead back to internet hardware that may be introducing ground loops.

If it's not one of these obvious causes my general method is first to isolate which component is causing the issue. I like to use a a RCA ground loop isolator for this. I put it along the different audio paths and can often narrow it down to the specific unit. I then try to adjust the power source plug location as this will often solve the issue. Also, typically having all the components running of off one power line and even ideally off one outlet seems to be the least ground loop inducing. If that still doesn't solve the issue I will try to ground components manually via wire to see if there is some inherent grounding problem in the components. Last, if none of these methods are working I start trying different random power plug configurations. Sometimes you can eliminate or cut down on the ground loop significantly by trial and error.

[artoly]

Thanks for your continues help RJ.
Crickey. Fickle power, floods, termites .... even eating your Maggies! That's terrible! I'm sure you are in a safer CJ zone now.

".., nothing really worked significantly until I completely isolated the entire Audio rig onto a separate AC mains phase...."

As you and others here will have done, one or more large separate mains feeds from the switchboard to the audio might be a good step for me (Dedicated Radial/s). It may not resolve the amplifier's ground loop problem, but would be a great added bonus if it did. I have been putting it off because I have never been sure how long I would live in the current house and it's a tweak that you can't take with you.

"...The Prem350/A is a very straightforward design with quite a high Class A bias, which CJ doesn't divulge much. It's a formidable design and one hell of an extraordinary thing. The term "power amplifier" is actually an understatement! He referred to it as an "outrageous power amplifier!"'

I am constantly impressed by the what it can do, especially when the volume dials up. I feel fortunate to have it and wouldn't be surprised if it is the only one in my country.
I believe it uses about 200W in standby mode (I think that means about 0.9 amps), which would be explained by some Class A bias.

[artoly]

I've ran into ground loop issues before and that certainly sounds like what you are dealing with here.

They can be fixed but it does take some experimentation, careful power connection layout, and a little bit of luck.

I have sometimes wondered if it is something for a technician to fix at the power supply in the preamp or power amp. Would you happen know if that is a path that some need to take to fix ground loops?

No, I don't think it is due to faulty equipment (or at least 95% of the time it isn't).

First, I look for any potentially common noisy components. The classic is any component that connects to a coaxial cable (like cable television). Computers can also introduce ground loops. Look at components that may be connected via ethernet as those lead back to internet hardware that may be introducing ground loops.

If it's not one of these obvious causes my general method is first to isolate which component is causing the issue. I like to use a a RCA ground loop isolator for this. I put it along the different audio paths and can often narrow it down to the specific unit. I then try to adjust the power source plug location as this will often solve the issue. Also, typically having all the components running of off one power line and even ideally off one outlet seems to be the least ground loop inducing. If that still doesn't solve the issue I will try to ground components manually via wire to see if there is some inherent grounding problem in the components. Last, if none of these methods are working I start trying different random power plug configurations. Sometimes you can eliminate or cut down on the ground loop significantly by trial and error.

Thanks for the list of things to try. I have a little go at finding it from time-to-time and have another list of things to try out when I find time and inclination.

[admin]

The one other thing is to make sure you don't have any power cables near RCA cables, especially if it's a long unshielded run. I actually had a small ground loop happen in my hometheater's subwoofer as I run a really long RCA cable to it from my receiver. It was sitting on a power cable and moving it just an inch or two away solved it.

[Wildcat]

The classic is any component that connects to a coaxial cable (like cable television).

Or an antenna input. That one I learned from experience, and experimenting.

The issue with ground loops is that the ground point is not common. When I installed an antenna at another house, I didn't realize the buzzing/humming was from the antenna. The problem is that the ground for the house electrical is connected to a water pipe, where the ground for the antenna cable was through a copper rod hammered several feet into the ground outside the house. Those two different grounding points are the classic ground loop, as the grounds are each at a different potential--my audio system was effectively connecting two different grounding points together, creating an additional circuit over which the "crud" traveled.

Some interconnects attempt to break small-level ground loops by having floating grounds--one end has the ground connected to the shield of the RCA jack (which is usually at the source component) and the other end is left unconnected. I did that when I made some of my own interconnects several years ago and they were dead quiet.

Other hum/buzz from adjacent wiring can reflect the quality of the EMI/RFI shielding in either the interconnect or the power cord, but it's always wise for me to separate them as best I can. And yes, "crud" does travel over something like an Ethernet connection as well, and most components I know of do not use galvanic isolation to remove it. Ethernet cables come in variations like UTP, STP, or FTP (unshielded, shielded, or foiled twisted pair). Sticking to a good FTP cable in the vicinity of the audio system helps. (My streamer handles the galvanic isolation, but at least I know the cable is emitting the least amount of EMI/RFI in the vicinity of my other cables.)

I have a faint buzz/hum in my Premier 11 as well, and I'm thinking it's the amp. It was really bad a month or so ago but swapping the RCA 6FQ7s for the Brimars helped clear up most of it. But it varies. Some nights it's quieter than others. It's very faint but, due to listening at low volumes, it becomes clearer. The major problem is my wiring in the walls--I'm unable to run a dedicated line to the system easily, both due to the room's layout, and due to this being an addition to the house. (That, and we may relocate by the end of the year...but that's another situation.) As it stands, power for the outlets comes in at one outlet and branches off in two directions, and my system is in the third outlet past the first one (fourth in the chain). I already had to rewire that first outlet because the ground was disconnected.

I'm not in an ideal situation, in other words.

[artoly]

Ground loops sure can be fickle things to find.

I didn't go into detail about my efforts for the loop I encountered, being a little off the thread topic, but perhaps it is ok to elaborate a bit.

I mentioned previously that an iFi GND Defender removed the hum entirely, but with two C13/C19 adaptors plus the iFi the sound was slightly compromised. After more time this weekend trying to eliminate it without the use of the iFi, I gave in (at least for now). However, I did rewire some alternative mains cable plugs to remove one adaptor and I think that has helped. Some Blues are pumping out at the moment and it still sounds great (not my most typical genre, but I like to mix it up).

All the thoughts of things to try above are great and worth committing to memory or file, but I think I did the lot. My loop was between the Prem 350 and the ARC preamp, confirmed by completely disconnecting everything else. (Additionally, I only have fibre/Toslink connecting the TV and aerial, but that was unplugged by disconnecting the DAC and I stopped using a radio tuner a while back).
Steps I tried included the following:

- My main RCA's are shielded between the pre and pwr amps. I pulled as much apart as I could on the RCA plugs without desoldering, and am reasonably sure the copper shield is grounded both ends. Therefore, I then tried some budget unshielded RCA's, which made no noticeable difference.

- I moved components around on racks and added bigger separation between mains and RCA/speaker wiring. (Some permanent and some temporary with wires temporarily around the front of racks, etc).

- Then it was the mains cables and once again I swapped out my shielded ones (one source end connected) for unshielded.

- I trialed straight to wall plugs, a star wired mains block, and a conditioning isolating transformer (which is staying in for other voltage reasons previously discussed). Plus lots of random trialling of socket swapping with the above systems.

- I then unplugged everything so I could turn off every switched circuit in the house, to identify & record every outlet on each circuit. Once I had done that I trialed an extension lead to run the audio system off each fully separated circuit in the house (with as little on in the house as possible) to no avail. At this point I have not installed a dedicated radial/s for the system. Like Wildcat, I am also unsure if this is our end-game house.

- Wires were touched onto various RCA outers and also onto component box screws, and also onto earthed mains blocks, thereby connecting units to try and create additional earthing paths.

As mentioned, in my case the hum has been solved with some mains cable plug changes, combined with a GND Defender, and although it is not the exact solution I wanted, it's still great. I think it is time for me to just take it as a win and sit back with the music.

[admin]

Sounds like you are pretty much there. I wonder if the ifi GND defender is having a negative influence on the sound as it's either on your preamp or amp, but not both?

Perhaps one last cheap thing to dry is something like this that you can plug into the preamp and amp, and try the ifi GND defender downstream (or not at all): https://www.amazon.com/Splitter-Power-S ... B09KH2V3SV Possible that this configuration may help with the ground loop without the ifi or may alleviate the sound degradation with the ifi due to the fact that the ground filtering will be the same for both units (with putting the ifi GND isolater in line from power outlet->power cord->ifi->power splitter->amp+preamp).

[Big Dog RJ]

Yes mate, that's a good plan for the long term... if you can find and isolate that ground loop, then everything will be super quiet! The tunes will also be more enjoyable.

Placing certain appliances on separate AC mains phase supply is something that has to match your country's building codes for electrical supply. Over here (Down Unda Aus) normal residential homes are not allowed more than a single phase. Multiple phases only come into play where there's commercial activity or apartment style construction, Multiple dwellings within one building structure will require multiple phases.

It's not a Must Have thing/ installation for your audio gear. There are other ways of getting the best type of installation for your gear. For example, dedicated AC lines with separate CB's is one of the basic installations for better sound/ performance overall. I would definitely recommend this as the first important step to proper set-up. As I said before, the other types of AC mains treatments will heavily depend on your house, system location and system requirements. So you'll have to try and work out which type/s would meet your requirements best. There's no one type of magic solution that will work universally.

The antenna phenomenon is quite spooky indeed! I had one of my monoblocks that required urgent service, so I shipped it upstate to Queensland. It came back ok but when I powered up and played tunes, not only did I get the normal source signal but also radio channels! I could hear people discussing the weather and sports... uh? Bloody hell! I sent it back and they found a loose ground wire in the chassis... it was just hanging there touching the bottom plate, not secured properly in its right place. Came back safe & sound, and now extremely quiet. Absolutely zero noise. One simple ground wire caused such a drama.

Hopefully, you'll get all this sorted out soon and those fine tunes will be playing at the high Fidelity.
Cheers, RJ