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Help needed with system distortion and hiss

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Posted on May 17, 2015 at 03:08:37
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
NOISE PROBLEM ?
I SEEM to have developed a problem with background noise and some sound breakup as the volume is turned up ?
I have just picked up some s./h MA gold ref 20's or GR 20'S as they are known by and also some Audioquest midnight bi wire speaker cable. yesterday i got my first chance in a week to put my system back together using the new speakers and my Shanling CD100T Valve cd player and my Shanling SP80's mono block power amps, I gave everything a bit of a clean up using deoxit contact cleaner to clean all my plugs etc.anyway after connecting everything back up it just didn't sound quite right, i have some background his coming from the left (as you look at it) speaker when you put your ear close up to the speaker, the other speaker has a tiny bit as well but nothing compared to the left speaker,when I put a new cd on as it was playing it got worse and between tracks got quite loud ? along with the distortion when playing a cd it sounds a bit veiled as well ? now i have 2 ways of volume control, using the cd player built in pre or using the mono amps built in pre, thing is i'm not sure were to start looking to find out the problem ? could this be a valve on it's way out ? or a problem with the cd player ? again a valve on the cd player maybe ? any help would be greatly appreciated thanks, I have so far swapped the speaker cables to the other amp and the low level hiss followed them, i have swapped i/c at the amp l to right and vice versa but the hiss didn't move it stayed with the same speaker, the hiss changes when a cd is played into distortion and sounds awful and i'm really lost so would appreciate any help it driving me mad, thanks, Keith

 

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RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 03:25:33
driver8
Audiophile

Posts: 842
Location: Montreal
Joined: December 5, 2002
Sounds like a problem with the speaker. Do you have another pair you could swap (any old pair will do) and see if the problem persists? I had a similar problem with voice coil rubbing on one of my drivers. You can try to very gently push in the drivers with your finger and see id it feels rough or if there is any resistance. Good luck.

 

RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 06:13:12
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
I thought that at first but when you play a cd the distortion comes from both speakers, it would seem a bit unusual for it to be both speakers i would have thought, i have the same feeling about the amps, as there a 2 of them again unusual for them both to be faulty at the same time ?
as such i get the feeling it's a fault with the cd player but i have no other source to try the system with ?

 

RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 07:29:44
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
ok so today i tried different i/cs, different speaker cable, different speakers, all to no effect, but i did notice that using the cd player remote volume control caused quite a bit less distortion than using the mono bloc amps volume control, (both have in built pre amps) ?which has completely got me lost ?

 

RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 08:16:03
driver8
Audiophile

Posts: 842
Location: Montreal
Joined: December 5, 2002
Well, at least we know that the problem lies upstream from the speakers. If there is more distortion in one channel, try swapping the monoblock tubes to see if the problem follows the tubes. I would also try cleaning the pots.

 

RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 08:29:13
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
by pots if you mean the volume control then there is none as volume is controlled by the remote controll only, i only have a few spare el34 valves to substitute but i can try and swap them see if anything changes ?

 

RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 09:25:16
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
Trying new valves would be a good place to start. To solve the hiss problem, don't put your head next to the speaker.

 

RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 19:24:32
Todd Krieger
Audiophile

Posts: 37308
Location: SW United States
Joined: November 2, 2000
You would need to have someone visit and listen to the system.... The problem can be one of at least ten different things.... From mismatched impedance to a short in a power transformer to a leaky filter capacitor....

Aside from that, if you have alternative components to swap out in the chain, I'd swap out different items, until you find the culprit(s).

 

RE: Help needed with system distortion and hiss, posted on May 17, 2015 at 23:47:00
stehno
Manufacturer

Posts: 739
Location: Oregon
Joined: November 8, 2001
Well,if you have a built volume attenuator in the CDP, then by all means disconnect the preamp and run the CDP straight to the amps so you can start eliminating what is or isn't the problem.

Don't forget to adjust the volume down on the CDP before making this change.

Other things to check:

1. Since you've been disconnecting things, double-check all ic's,and speaker cable connections for tightness.

2. For the tubes, perhaps pulling them out and reseating them.

3. If you've got the wherewithal, pop the tops on all of your components to ensure all screws and connections are taut or tight.

4. If the are mono blocks, reconfigure them so they now power the opposing speaker to see if the distortion switches speakers.

5. Do the same thing with your interconnects except swap only pair at a time.

5a. At the preamp, swap the CDP's interconnects L into R and R into L and listen.
5b. At the amps swap the preamps interconnects L into R and R into L and listen.

6. Try inserting an extra pair of interconnects.

If you still have the problem, at least at this point you should have isolated which component or cable is the culprit.

 

" Trying new valves would be a good place to start. ", posted on May 18, 2015 at 06:01:31
+1. Try replacing input stage tubes, with selected quiet ones.

Good luck!

 

RE: " Trying new valves would be a good place to start. ", posted on May 18, 2015 at 09:48:43
I believe the Shanling CD player has both tubed and solid-state outputs.Have you tried the SS output? It would seem to me that you might be ready for a tube change.Any idea of the age/operating hours on the tubes? Both CD and monos.
I would consider fresh tubes from Shanling and possibly Fine-tune with a few NOS-after the noise and distortion problem is cured.
Don't be surprised that your sound changed after a tidy-up.It takes at least 3 days for the system to settle after this process.Had same problem after the Dennessen de-mag disc.Was happy when things got back to normal.

 

RE: " Trying new valves would be a good place to start. ", posted on May 20, 2015 at 03:25:09
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
ok so here is what i have done so far
swapped the speaker cable
i have swapped the speaker cable to the other mono amp, the hiss at low volume followed it but the distortion when playing is the same from both speakers
i have tried new i/c's
i have swapped i/c's over l to R etc no change
i have tried a different speaker, no change
i have tried the none tube outputs on cd player, no change
i have been told that the valves are pre out valves and to check them ?
so that will be my next step i think

 

RE: " Trying new valves would be a good place to start. ", posted on May 20, 2015 at 05:14:31
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
Well yet another failure, boy am i getting pissed at this
swapped the cd player valves for the original and guess what, no change everything is working or not working as it was, sooooo it's not them valves thats not working ? but if i turn the cd player volume to 0 and try and just use the mono amp volume it doesn't work ? i.e. no sound ? no i was led to believe that the mono amps had a built in pre section so if i turned the cd volume to 0 which is basically off then should the mono amps take over the duty o using their built in pre section ? i could do with a home visit really of someone who knows what they are doing because i'm chasing my own tail here and getting no where ?

 

First..., posted on May 20, 2015 at 06:18:52
Cable problems can cause distortion but they don't not cause hissing noises, so there's your first clue. Disconnect the amp and the CDP. Hook up a cheap old used stereo receiver, the kind you find at the second-hand store (NO raspberry beret required!), and dial in a radio station.

Is the noise and distortion now gone? Re-connect the CDP and listen to it. If things still sound OK, you'll know where the problem lies.

 

RE: First..., posted on May 20, 2015 at 10:40:24
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
OK Guys
plugged

 

RE: First..., posted on May 20, 2015 at 11:59:24
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
OK Guys
plugged £15 dvd player into the mono amps and..................................yeah no distortion played perfectly, but stop playing and that low level hiss is still there ? so I swapped the L - R i/cs round and still play great but hiss in same speaker, so i then tried swapping the speaker cables from one mono amp to the other, still plays great but hiss now in the other speaker that i swapped the speaker cables too ? so what does all this mean ? cause i'm lost, yeah different source and it plays fine but when you stop the cd and listen to the speakers close up 1 of them has some hissing in it ? oh and i swapped the mains leads etc just to check.

 

RE: First..., posted on May 20, 2015 at 12:26:05
driver8
Audiophile

Posts: 842
Location: Montreal
Joined: December 5, 2002
So we now know that there is an issue with the mono amp directly connected to the hissing speaker. Swap tubes with the other mono amp. If the hissing then switches to the other speaker (i.e. follows the tubes), there is an issue with one or more of the tubes, if there is no change after doing the tube swap and the same speaker hisses, then the problem lies with the amp. This may prove a little more difficult to diagnose so let's hope it's the tubes. Cheers.

 

RE: First..., posted on May 20, 2015 at 13:18:42
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
no when i switched the speaker cable at the amp end from one amp to the other amp why does it matter ?

 

RE: First..., posted on May 20, 2015 at 13:27:10
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
so if the distortion has gone when using a different source then surley the cd player has the main problem yes ? as for the hissing you have to put your ear to the speaker to hear it but as the other side is totally silent it tells me there is still a slight problem and although not a big one a problem all the same, maybe the amp valve bias is out a bit or something similar ? all the same it looks like i'm going to have to send both the cd player and mono amp to the shop to be checked

 

RE: First..., posted on May 21, 2015 at 07:23:58
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
ok guys I just swapped the EL34's out of the noisey mono amp and no change so then i tried the other 2 tubes, i didn't have replacements for these so i just used the tubes from the other mono amp and guess what the hiss is still there but only about half as much ? talk about confused i really would love to know what's going on ? it would seem to me that whatever is causing the hiss is based around one of the front 2 tubes i will check which one later, but i'm another step forward i guess

 

Why some people hate tube gear... (nt, posted on May 21, 2015 at 08:10:46
.

 

RE: Why some people hate tube gear... (nt, posted on May 23, 2015 at 08:48:41
keith41
Audiophile

Posts: 13
Location: England
Joined: March 24, 2012
ok guys
latest news is that in have spoken to the local dealer and he is going to get my cd looked at, i will get some nice new tubes for the amps and if the hiss continues then i will get the offending mono amp looked at as well, thanks for everyones help

 

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