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Post by musicmanic on Aug 1, 2011 20:55:56 GMT
I've just had my X-can V2 modded but I'm now getting a ground noise. I have my headphones at full gain to test for any noise.
After a few tests I found that the metal fader shaft makes a grounding noise when you touch it (like when you touch a guitar cable attached to an amp).
Also fader shaft movement creates a crackling noise. Faulty pot maybe?
There is a slight hiss also, even at no gain.
Any ideas on what the problem is?
Just performed some more tests and I can get rid of the ground noise if I force the Fader into the right position with the phono cables plugged in. The ground noise is still there without the phono cables plugged in. Will I need to get the fader fixed?
Thanks
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Post by PinkFloyd on Aug 1, 2011 21:46:48 GMT
Hi James,
As explained Via email... the amp is totally silent when isolated from the rest of your equipment SO it's a case of finding out what's causing this.
The pot is NOT faulty but it is always a good idea to isolate the pot shaft by fitting the rubber knob.... this will, at least, get rid of the "buzz when you touch it" problem and then you can concentrate on exactly WHAT is causing the grounding problem.
First thing to check is the amp ITSELF..... plug it into a mains socket and connect headphones..... does is buzz?
If so then send it back, there is clearly something wrong.
If it is silent (within limits) then you can pretty much rule the "amp" out as the problem.
It's, unfortunately, a process of elimination and a case of testing out everything in the chain to find the culprit.... having no experience of your setup I can only tell you that the amp does not have a problem (did not have a problem when it left here) but, if you feel it is causing the problem then please send it back and I will go over it with a fine toothcomb......
What "exactly" is in your mixing rig and did the amp perform OK before the mods?..... the more details you can supply the better.
All the best,
Mike.
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Post by musicmanic on Aug 1, 2011 22:17:55 GMT
Hi James, First thing to check is the amp ITSELF..... plug it into a mains socket and connect headphones..... does is buzz? If so then send it back, there is clearly something wrong. If it is silent (within limits) then you can pretty much rule the "amp" out as the problem. .... What "exactly" is in your mixing rig and did the amp perform OK before the mods?..... the more details you can supply the better. All the best, Mike. There is a slight buzz at high gain but I think that's naturally from my light switch which is touch sensitive. I also get a buzz in the normal unmodded X-Can v2. The things is that the modded v2 has a heavy grounding buzz when I touch the fader pot (even with the knob attached). If I touch the fader and chassis then the noise decreases. If I push the fader to the left then the noise stops but if I push it to the right then in re-emerges. It's definitely a grounding problem within the unit Mike. The phono cable is helping it ground more, which surely can't be right. Isn't that down to the cable inside? I will check my old X-can v2 now! Thanks |
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Post by PinkFloyd on Aug 1, 2011 22:45:45 GMT
James,
PLEASE send it back and I will retrofit it to the way it was AND refund you..... I really don't have the time (nor the inclination) to waste time repeating myself (In parrot fashion)...... there is NOTHING wrong with the amp...
Have you tried what I suggested and isolate it from the rest of your gear? If it behaves the same way "isolated" from your mixing studio gear then there is a prob with the amp.
Mike.
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Post by PinkFloyd on Aug 1, 2011 22:48:47 GMT
I will repeat my question AGAIN.....
If you isolate the amp out of the "chain" does it still buzz?
Yes / No ?
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Post by musicmanic on Aug 2, 2011 0:00:00 GMT
Yes repeat Yes. I've told you that Mike.
All the buzzing of the fader pot happens with just the amp plugged into the mains.
Just in case you didn't hear, YES ;D
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Post by musicmanic on Aug 2, 2011 0:01:42 GMT
Scottish temper or what! Blimey!
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Post by Deleted on Aug 2, 2011 0:29:51 GMT
Scottish temper or what! Blimey! I have previously refrained from posting, in the hope that this would sort itself out, due to Mike's clear suggestions. The words "fader pot" keep getting repeated. Are you referring to the Fader pot in the MIXER, or the VOLUME CONTROL in the amplifier ? IF you are referring to Fader pot in the mixer, then going by your descriptions,common sense would suggest that the mixer most likely has a problem, or it's connecting leads do. >60 years experience as a DIY hobbyist leads me to that most likely scenario. Also, many mixers have too high an output level for use with many preamps and amplifiers, and volume control is then often very abrupt and difficult. SandyK P.S. A slight hiss at minimum volume is not unusual with many valve amplifiers. |
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Post by Deleted on Aug 2, 2011 7:20:23 GMT
Watch it ...... we all bite here you know.  If it buzzes with nothing connected, one check you can easily do is look at the back plate and make sure that the wire that goes under one of the screws is actually under the screw and not floating. Also make sure that there is a good metal contact between that lead and the chassis. I forgot to connect it once when I changed a tube and it buzzed but it was loud.  If it doesn't buzz when nothing is connected, then it's not the amp. Ian |
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Post by musicmanic on Aug 2, 2011 13:45:01 GMT
Scottish temper or what! Blimey! I have previously refrained from posting, in the hope that this would sort itself out, due to Mike's clear suggestions. The words "fader pot" keep getting repeated. Are you referring to the Fader pot in the MIXER, or the VOLUME CONTROL in the amplifier ? IF you are referring to Fader pot in the mixer, then going by your descriptions,common sense would suggest that the mixer most likely has a problem, or it's connecting leads do. >60 years experience as a DIY hobbyist leads me to that most likely scenario. Also, many mixers have too high an output level for use with many preamps and amplifiers, and volume control is then often very abrupt and difficult. SandyK P.S. A slight hiss at minimum volume is not unusual with many valve amplifiers. I meant the VOLUME CONTROL in the amplifier. The noise is when the amp is in isolation. I have stated that. I'm no tech expert. Again, touching the "VOLUME CONTROL in the amplifier" creates a buzzing sound the same as when you touch a guitar cable when it attached to the amp. So to answer Mike's question..YES. When I push the VOLUME CONTROL in the amplifier to the side it goes away, but that shouldn't be required right? Thanks |
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Post by Deleted on Aug 2, 2011 14:05:15 GMT
Maybe a postal enhancement? I hope the postal staff enjoyed their football game with your amp  |
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Post by musicmanic on Aug 2, 2011 14:07:05 GMT
Also, many mixers have too high an output level for use with many preamps and amplifiers, and volume control is then often very abrupt and difficult. SandyK Could you expand on that please Sandy. Aside from this post, the volume level comes in quite high from my soundcard outputs when the X-Can volume pot is low. Does this mean my soundcard outs could create too high a voltage for the X-Can? Will that distort the sound in any way? Maybe its safe to turn my soundcard output down by the mixer. Thanks for help |
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Post by musicmanic on Aug 2, 2011 14:31:57 GMT
Maybe a postal enhancement? I hope the postal staff enjoyed their football game with your amp That's what I thought at first! |
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Post by Deleted on Aug 2, 2011 14:42:18 GMT
Take the back plate off and check that wire out. Or, it could be as Chris says, PO football. Ian |
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Post by musicmanic on Aug 2, 2011 15:33:26 GMT
Ok I will take the ground wire off and listen.
Why would the volume fader create a buzz though if it was out of place?
Thanks
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Post by Deleted on Aug 2, 2011 16:15:39 GMT
Ok I will take the ground wire off and listen. Why would the volume fader create a buzz though if it was out of place? Thanks It doesn't need disconnecting!! Check that it is actually connected to the chassis. It may not be earthed? The wire is inside the back plate and needs to have a good contact with the body of the amp. Mike scrapes away a little paint behind it to ensure a good earth normally and the back plate screw should go through it. It's just that I forgot about it on mine and wondered where the buzz was coming from until it dawned on me. It's an easy one to overlook because it's not noticeable from the outside and is easily missed when the back is off. The wire can curl up inside the body of the amp. My modded V2 is very quiet and I don't detect noises at all. Are you using low impedance headphones? Ian |
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Post by musicmanic on Aug 2, 2011 16:29:16 GMT
It doesn't need disconnecting!! Check that it is actually connected to the chassis. It may not be earthed? The wire is inside the back plate and needs to have a good contact with the body of the amp. Mike scrapes away a little paint behind it to ensure a good earth normally and the back plate screw should go through it. My modded V2 is very quiet and I don't detect noises at all. Are you using low impedance headphones? Ian It's attached to the scraped part of the plate. I'm using Sony MDR's 7509 which are 24 Ohms. |
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Post by Deleted on Aug 2, 2011 16:53:06 GMT
OK, if the wire is attached, then the earth is connected there. The headphones are very low impedance and would be prone to pick up hiss.
OK, I just tried mine with everything disconnected. It's just plugged in, no interconnect.
Here's the funny thing:
DT990 pro (250 ohm) perfectly quiet. On full volume as well.
ie8 (16 ohms) I get a hiss and buzz at full volume which varies by touching the volume knob and decreases if I touch the chassis of the V2. However, attach something and it goes.
Have you got a higher impedance headphone to try? 24 ohms is a little bit low for a V2 perhaps and is very prone to picking up noise in any case. (Also, 24 ohms does need quite a lot of current)
So, try a higher impedance headphone if you have one.
Ian
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Post by musicmanic on Aug 2, 2011 17:22:22 GMT
Here's the funny thing: DT990 pro (250 ohm) perfectly quiet. On full volume as well. ie8 (16 ohms) I get a hiss and buzz at full volume which varies by touching the volume knob and decreases if I touch the chassis of the V2. However, attach something and it goes. Have you got a higher impedance headphone to try? 24 ohms is a little bit low for a V2 perhaps and is very prone to picking up noise in any case. (Also, 24 ohms does need quite a lot of current) So, try a higher impedance headphone if you have one. Ian Yes if I attach the phono ins to the outs of my computer then presto! Quiet with just the expected hiss! If it's normal for that to happen then fine. Just wondered if it were a ground problem or interference. I have the Sennheiser 650s which are 300 Ohms. I will do more testing when the Sun goes down. Must say this amp sounds great now. James |
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Post by Deleted on Aug 2, 2011 17:32:48 GMT
OK James. That's great. The V2 is possibly better with higher impedance headphones (like many amps) since it helps reduce nasties and noise. 24 ohms is bordering on a bit too low imo and so will be extremely prone to noise etc. My Beyers are deathly quiet and with most amps, if you put them up full whack, you would hear a 'presence' or low hiss. Actually, if I plug my Ipod in and turn up full whack, the Ipod hisses worse. It's noisier than the amp from the dock connection!! The V2 has a lovely sound and Mike is a genius with them all. I have a modded V1,V2 and V8 and they are all stunners. Really musical and engaging, so they deserve a better headphone. I don't know whether you have a Little Pinkie power supply but that helps to lower noise and increases the amp's dynamic range. Funny thing is how attached I've become to Mike's power supplies. They are built like a ton of bricks, are extremely quiet and really produce a proper kick for the amp to draw as much as possible for better tubes as well. They are a quality product and have really attuned me to the importance of power supply. So you can relax with the music ......... Mike is an expert.  Keep the Sonys for portable. Ian |
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Post by PinkFloyd on Aug 2, 2011 19:50:17 GMT
Hi James, I wasn't "angry" last night, that's just my writing style  24ohm is way too low for the V2 in my opinion and they will humbuzz like a beehive.... you could always fire an inline resistor into the equation if you MUST use the Sony 'phones.... something between 30 and 90 ohm would be worth trying:  For "monitoring" you want as little noise as possible so are, ideally, looking for a pair of 'phones in the 120 - 600 ohm region.... with these you will get almost ZERO audible noise. I wish you'd told me the impedance of the 'phones last night, that would have explained a LOT The Senn HD-600 will be silent, in comparison to the Sony low Z 'phones, and pretty much "problem solved".... I can make you an adaptor for your very low ohm 'phones which won't change their sonic characteristics very much but will make them more suitable for use with the V2..... the low ohm 'phones are great with ipods / MP3 players etc. as they are pretty easy to drive but can be problematic when driven by some amps (noise wise).... 32 ohm Grado 'phones are pretty "silent" with the V2 but some other low Z 'phones are a nightmare and really do require and inline impedance adaptor to silence them. Sometimes, the impedance adaptor can actually IMPROVE the sound quality..... amazing what the humble resistor can do  Another little tweak, if you are experiencing "twilight zone" stuff, is to ground the body of the pot to the chassis (easily done).... if you are in a high RFI area and are picking up taxis / police broadcasts you can also get rid of that by fitting some strategically placed axial ferrite links. I don't think you need to do either, the 24ohm Sony kinda explains it all Ian is correct re: the Power supply. The "stock" PSU is pretty erm "basic" (and TOTALLY too weedy for the job).... a decent PSU will definitely lower the noise floor / improve the SQ by quite some margin. I discussed that with you and put you off buying a Little Pinkie at the same time as having the mods done..... best to listen to the stock V2, then the Modded V2 and then the modded V2 with Pinkie.... that way you will realise that what you are paying for actually WORKS and you will hear the improvement that each change makes.... If you went for everything at once (blunderbuss approach) you wouldn't be aware of what did what..... Much the same as a Doctor, he has MANY antibiotics available to him and only a foolish Doctor (and patient) would go ahead with the blunderbuss remedy (everything, all at once).... sure, it would cure the problem BUT the Doctor AND the patient would be none the wiser as to what did what / where Getting it "right" is a lengthy process and it cannot be achieved by the blunderbuss approach.... I learnt that a LONG time ago All the best, Mike. |
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Post by musicmanic on Aug 3, 2011 0:11:07 GMT
Hi James, I wasn't "angry" last night, that's just my writing style Could've fooled me ;D Don't worry I live in London so I've heard much worse[/quote] Yes please, add it to my order. It would be a nice accessory. Ye as I said I'm no techy! Yep! Sennheiser 650s working just fine now. Ok I'm gonna order Pinkie from you but not use it with Mod for a while. I'll try it with stock X-can. Ye tell me about it. All this time and I wondered why Sony's were so loud. Thanks for your help guys. Please email about bits Mike. Cheers |
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mrarroyo
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Our man in Miami!
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Post by mrarroyo on Aug 3, 2011 2:18:42 GMT
Hi, are you using the MF PSU? If so is it grounded? The fact the noise goes away when you connect your source it is then how it gets grounded (via the ic's) and thus why the noise goes away.
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Post by musicmanic on Aug 4, 2011 0:44:55 GMT
Hi, are you using the MF PSU? If so is it grounded? The fact the noise goes away when you connect your source it is then how it gets grounded (via the ic's) and thus why the noise goes away. Not the original mrarroyo. It happens with an unearthed plug too. It's just a trait of valve amps and they needed the pot to be earthed. |
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mrarroyo
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Our man in Miami!
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Post by mrarroyo on Aug 4, 2011 10:38:10 GMT
Actually SS amps should be earthed as well.
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