CJ Premier 17LS Hum Noise

[Rajkumareswari]

I would like to share my experience, I owned CJ Premier 17LS few month ago I have problem with hum noise from preamp . When I connect my power amp into CJ preamp I heard sound. I had checked and found ground OK, I can't solve this issue quite long time and I decided to remove CJ from my system and connect my Onkyo P-388 into tube mono power amps. Recently last week I had resolved hum issues. I had noticed hum noise came from left channel only and Intermittently, I was suspect pre-out relay may poor contact led hum noise, I do not have spare relay and not possible buy from local market. I decide to swap relay "EPL Theatre Out" which one never use with Pre-out and the problem solved , since week no noise) I hope there will be no more hum noise. May I correct in case of output relay (probably mute relay) poor contact can lead to hum noise? Yesterday I was ordered new relay from eBay 2USD (original NEC)
Please where do I found CJ Premier 17LS schematic on this forum?

[plurn]

Well done fixing the hum problem. I am impressed that you were able to narrow it down to the relay so quickly. I would have suspected some other cause such as tubes or ground loops. Not sure I would have the knowledge to suspect the output relay.

When the relay was removed, were you able to test the relay to determine if it actually had bad connectivity with an ohm meter or other tool? pinouts for the relay: http://www.farnell.com/datasheets/1252592.pdf

The schematic for CJ Premier 17LS is available on this site in the Troubleshooting/problems/manuals/schematics section.

This page:
viewtopic.php?f=17&t=128

Seems to be in both of these files:
"Part 1" Schematics file
"Part 4" Schematics file

Anthony

[admin]

Good diagnostic work on finding the relay.

@Anthony
Thanks for catching the dual file locations, I consolidated both copies of the Premier 17 LS into the "Part 4" schematics file.

[Rajkumareswari]

Hello I need help, after swapping out relay there was no problem 2 weeks and yesterday I noticed the problem return back YES. I had replaced new relay still problem not solved. Relay pin number 8 & 9 left / 2 & 3 right NC when mute will open contact. I had confirmed this is not relay issue. Please note this I heard 17ls white noise (his noise like radio between stations ) not a humming noise. Anybody can help me resolve this issue? I have problem only left channel, sound came intermittently.

[Big Dog RJ]

Hey mate, not too sure whether you solved this problem or not but I strongly feel that your hum/hiss as you finally identified isn't really an issue.

For as long as I have used CJ preamps (nearly over 25 years) nearly all of them have this hissing noise in the left channel. This is normal for CJ preamps and don't ask me why because that's a whole different discussion at a totally different level.

This hiss will not increase as the volume level increases, it will remain constant, and sometimes disappears altogether but comes back on during certain times. It is also quite noticeable from a distance but once music is playing, you really cannot hear it.
The preamps which gave me this hiss (always left channel) were as follows:
Prem17LS, CT5, ACT2 and ET5 & GAT (didn't own a GAT or ET5 but demoed at home and always had a hiss on the L ch)
The preamps that didn't have a hiss and were very quiet: PV8, PV10AL PV12, PFR, PV15, Classic SE, ET3SE, CT2 & CT5 (later used a CT5 which was quiet).

So as you can see this is a normal phenomenon with CJ amps, just to cut a long story short- it is all about how the gain stage is designed with those particular tubes used for input to output stage. Some CJ amps in the older versions actually used more than one gain stage, others used only a single stage and made their circuits simpler with zero feedback designs but this also relates to other issues down the line, such as the occasional hiss...

Overall, a single gain stage and "phase inversion" circuit preserves the phase and should give you a more fuller/richer/purer sound and that is what matters the most.
It may seem that replacing your relay was not really required.
Anyway, I sincerely hope that you are getting that full rich sound from the Prem17LS
Cheers, RJ

[plurn]

I owned CJ Premier 17LS few month ago I have problem with hum noise from preamp

Please note this I heard 17ls white noise (his noise like radio between stations ) not a humming noise. Anybody can help me resolve this issue? I have problem only left channel, sound came intermittently.

Just so we are talking about the same things. Hum noise (50 or 60 Hz sound related to the mains power) is different to hiss noise (like radio between stations) and they have different causes. It sounds like you are saying that initially you had hum noise, and now that is gone and you have hiss noise but it is intermittent. Let us know if that is not correct.

So hopefully we can ignore the hum problem and look into the hiss problem.

From my experience, hiss noise is a description of what I have heard called "tube rush" or tube noise. It is what happens to tubes when they get old or begin to fail. It can even happen to fairly new tubes. It typically starts at a low level when they are old, and the noise gets louder over time as you keep using them. Though in one case I have had a tube start to go noisy with hiss and then it went quiet after about 50 hours of further use - this is not very typical.

You have not indicated if you have done any troubleshooting with trying different tubes or swapping the tubes you have into different sockets. I think that would be a good easy test. Here are some suggested tests:

- With the power off, carefully remove and replace each tube in their original sockets. So you are not moving the tubes to different sockets in this case. Turn on the power and test if that has fixed the problem. This is just to reseat the tubes to make sure they have good contact with the sockets. If this does not fix it, continue on.

- With the power off, take note of which tube goes in which socket and carefully remove the tubes. Swap the front two tubes with the back two tubes and place them back in their sockets. To try and clarify that, the front two tubes move to the back two positions, and the back two tubes move to the front two positions. Turn on the power and test if the problem is the same, or has the noise moved to the right channel? If the noise has moved to the right channel then there is a very good chance that this is just a problem with some of the tubes and replacing them is likely to fix the issue. If you still have noise in the left channel, then it might not be the tubes that are the problem and further investigation is needed.

- If you have spare tubes, you could try them in your preamp to see if the problem goes away. I think the previous tests would be sufficient however.

With that second test, I am assuming that the two front tubes are for one channel, and the back two tubes are for the other channel, but I am not certain of this. According to this post from Joe Appierto it seems to be the case viewtopic.php?p=4674#p4674

" ... In the 17LS tubes V1 and V2 are for the right channel and V3 and V4 are for the left. ... "

Anyway they are some easy initial tests you could try if you have not already done similar tests.

Anthony

[Big Dog RJ]

great suggestion there Anthony, and spot on with that.

According to Raja first he stated that it was a hum, then he did a relay fix (which was probably not necessary), and now he says it's a "hissing" noise...
What the hec is going on?

Anyway, those preamps I've used including the last top line ACT2 always hissed regardless of what tube I tried. In fact called Ed and spoke to Lew about it as well and he said this was fairly normal, at the time I had the PFR and PV12, both had this hiss on the L ch. You can try to source tubes that don't have the tube rush / noise but these are very hard to find and probably not worth pursuing. This is mainly due to the specific gain stages that are designed by cj and I noticed this hiss to be more apparent mostly in their premier standard pre's. At the end of the day, it would also make you paranoid about this hissing and render less enjoyment of music...

I was told as long as the hiss doesn't increase with level that's quite normal for cj preamps. I also remember ARC and Jadis pre's having a similar phenomenon on some of their entry level pre's but definitely not their top tier stuff.

I was also told by cj that the power amp should be totally quiet with all tubes in place and biased properly. Only just a very slight hum from the mains tranny could be heard if you were to press your ear against it, and that's about it.

Sometimes I noticed that when I tried my ACT2 and other premier pre's I had with a horn system, this hiss was really annoying. Hence, another reason why I never liked horns. But of course that hiss would be disguised once music started playing.

I hope that Raja gets to identify the actual hiss and what he's actually hearing. From that perhaps he would be able to better understand what's going on with his prem 17LS and what needs to be done or should be left alone.
Let us know what you discovered R,
cheers, RJ

[Rajkumareswari]

Hi RJ and Anthony thank you for quick reply. Firstly I'm not electronic expert, I'm mechanical expert I knows 50% in electronic (Working in caterpillar)
Yes I was wrong, first time heard hissing sound not hum noise. Yes relay not necessary to replace, I was put it back the original. This hiss sound I heard just few months ago, since last 3 years runs very quite. When run CJ 17ls with 845B tube power driven my Tannoy speakers, I heard irritating hiss sound on my speaker sensitivity 95dB/W/m. Yes I agreed with RJ hissing sound not increasing when increases volume or playing music. I was think as much as quite HI END music can enjoyable.
Thanks Anthony, I will going to try as you mentioned troubleshooting steps and hope I will solve this problem. Only very surprised why this hissing sound came only Left channel? Why CJ can't find solution solve this issue for CJ owners? Raja

[Big Dog RJ]

Hey Raja,
OK, I thought as much that was the type of hiss that you were experiencing... correct!

Unfortunately, CJ cannot and will not address this hiss. It is part of their design and sometimes with high sensitive speakers, this can be very annoying.
Your Tannoy's would pick this up very easily and horn speakers would pick this up by a far greater margin. It is a real pain in the butt with a capital "B"!

Like I said the only way to completely get rid of this hiss is to try different tubes and pick the ones that are quiet but this means that you are going to purchase a lot of tubes... I wouldn't bother with this venture because there are no tubes out there that are extremely quiet, unless you happen to try some particular brand of tube on a different system having the same cj preamp as you have.

Or try the suggestions made out by Anthony and see if that helps. What I have found to work was using at least two sets of tubes, one was as quiet as possible and the other set just for back up purposes.
Anyway, I hope you at least enjoy your music on those Tannoy's !
Cheers mate, RJ

[Rajkumareswari]

Hi friends, update information regarding hissing noise CY 17LS, I had swapped pair tube in left to right and the problem hissing sound was shifted from left to right channel the roots cause is confirmed tube itself. I had cleaned tube contact pins (socket not possible to clean) after this excises right channel hiss sound almost reduced to 25% I can't heard hiss from my listening position anymore ! (If I go closer to speaker I can heard) I still suspect possibly tube pins is poor contact (found pin all greenish). I was order set of TELSA 6922 tube gold pin and need order set of gold pin socket probably can 100% eliminate hissing sound. Kindly confirm tube socket for CJ 17LS PCB mounting I will going to order from eBay. http://www.ebay.com/itm/142110095626. Thanks Anthony and RJ. From Raja.

[Rajkumareswari]

Hi I have two pairs E88CC tubes instead of 6922, can I try on my CJ premier 17Ls? Thanks Raja

[Big Dog RJ]

Hey mate, if you are having oxidised pins on the tubes then this is definitely time to replace all tubes!
This should be better in the long term since then you would have a full replacement set for your 17LS.

Re. to ECC tubes vs 6922, I would just stick to what cj had in the 17LS as the original type. I have also found the 6922 to be a better and more stable tube with less tube micro-phonics... You would have to investigate a bit more and see if the ECC type gives any added benefit to the overall sound. If it doesn't then there is no point in having this tube as a long term config. The 6922 is also a current tube that cj is using in nearly all of its triode circuits, so there should definitely be something worthwhile in keeping this tube.

BUT, the main thing is YOUR ears, if you do actually prefer the ECC type over the 6922, then perhaps you may prefer its overall sound. However, this sound can also change with the power amp. I have found rather than the preamp, changing output tubes on the power amp made the most significant change in altering the sound. The preamp is mainly a switching device and should allow the music to flow through as transparent as possible without adding artifices to the signature of music being played. If that can be accomplished, that is one good preamplifier design!

[plurn]

Hi I have two pairs E88CC tubes instead of 6922, can I try on my CJ premier 17Ls? Thanks Raja

As I understand it E88CC is an improved version of ECC88. 6922 is an improved version of 6DJ8. Perhaps that means E88CC = 6922?

There is certainly no harm in trying E88CC in your CJ premier 17LS. It is electrically compatible. It would be interesting to find out if they fix the noise issue.

Anthony

[Rajkumareswari]

Anthony, Yes has been replaced existing 6922 with E88CC - 2 pair gold pin the problem was solved , no more hiss noise very quite now my CJ Premier 17LS. Also I like the sound of E88CC (TELSA) better than 6922 initially, if I run brake through will excellent sound. Mid is more detail. Also I was ordered gold pin socket very soon will replace.
I have another problem with my CJ Premier 17LS remote control, during build my new house, I was not use this amp and remote around year, battery got leaks and damaged PCB board of remote and IC PT2461, I have ordered new IC now I am looking PCB board, do you have any idea source of remote PCB? Anyway I have Logitech Harmony One & Elite can control my CJ Premier 17LS 100%. Still I like to repair CJ remote. Thanks Raja

[plurn]

Hi Raja,

I am glad that solved the noise problem. I would think that the 17LS would already use high quality tube sockets since it is a premier model. Are you sure the existing ones are not gold plated?

Regarding the remote, I don't know where you could get a replacement PCB other than maybe a distributor or direct from CJ (if there is no local CJ distributor in India).

I think CJ has only ever had two different remote models over the years - RC-10 (plastic) and RC-20 (metal). I think your 17LS uses the RC-20. Even the GAT and ET5 uses this remote so you could perhaps even just order a replacement remote? No idea of the cost.

This is a guess but I expect the RC-10 and RC-20 transmit the same signals and may be able to be used with any CJ preamp that has remote control. Just a guess. The RC-10 is less wide so I expect it has a different PCB.

This company seems to sell the plastic RC-10 for US$49 http://www.audioclassics.com/detail?detail=RC-10
I don't know if they ship to India. Perhaps they can obtain an RC-20?

How damaged is the remote? Can you try cleaning the PCB etc with Isopropyl alcohol (isopropanol) (pure 99+%), letting it dry out, use new batteries, and then seeing if it works?

Anthony

[Rajkumareswari]

Anthony, existing tube sockets not gold contact, normal one silver contact I had noticed those contact also oxidised, I was clean all socket before install new tubes, but this socket will not serve longer may oxidised very soon. This is the reason I ordered new gold pin socket. Yes my remote model RC-20 gold metal. Battery leaks and oxidised PCB tracks as well as IC pins, I was try to repair tracks and replace IC, repair 24 track damaged for IC not possible. CJ no distributor in India. I want RC-20 remote otherwise Logitech universal remote control very well. Thanks Raja