strange noise - link to 50kb audio clip inside (mp3)

Eric Klinger · Post by **Eric Klinger** » Thu Jun 02, 2005 11:24 am

http://www.digitalsoundplanet.com/Virtu ... ltid=28420

I seem to be having an issue that sounds like a bad cable... I've switched them a few times thinking that's what it was... it seems to go away after the first five minutes the amp is on. Any ideas? Perhaps a cold solder joint somewhere? I wouldn't doubt I have one as I used 2 different solders (ran out at one point and used another) that didn't seem to melt quite as nice when I recently installed my new PTP board... 1976 JMP 2203. Now that the amp is warmed up (so it seems) the noise has gone and hasn't come back... until the next time I turn it on after being off for a while.

Also - sometimes when reading voltage on pin 3, I will hear a pop from the speakers and then all of a sudden the hiss from my speakers is gone and it sounds like it's coming out from the tubes.

It would appear I have a bug or two left in this... sounds great - I am very happy with it.

Thanks all for your help, past and present.

Eric

Guest · Post by **Guest** » Thu Jun 02, 2005 6:07 pm

Eric Klinger wrote:http://www.digitalsoundplanet.com/Virtu ... ltid=28420

I seem to be having an issue that sounds like a bad cable... I've switched them a few times thinking that's what it was... it seems to go away after the first five minutes the amp is on. Any ideas? Perhaps a cold solder joint somewhere? I wouldn't doubt I have one as I used 2 different solders (ran out at one point and used another) that didn't seem to melt quite as nice when I recently installed my new PTP board... 1976 JMP 2203. Now that the amp is warmed up (so it seems) the noise has gone and hasn't come back... until the next time I turn it on after being off for a while.

Also - sometimes when reading voltage on pin 3, I will hear a pop from the speakers and then all of a sudden the hiss from my speakers is gone and it sounds like it's coming out from the tubes.

It would appear I have a bug or two left in this... sounds great - I am very happy with it.

Thanks all for your help, past and present.

Eric

Have you ruled out tubes?

Guest · Post by **Guest** » Thu Jun 02, 2005 6:30 pm

no

I will though

Eric · Post by **Eric** » Fri Jun 03, 2005 3:13 pm

It's hard to tell. Everytime I turn my amp on for the first time of the day it does this. Each time it does, I quickly turn it off and change tubes... it doesn't do it. But then I change the tubes back to my JJ's and it doesn't do it again... and it won't do it again, until tomorrow morning.

Eric Klinger · Post by **Eric Klinger** » Sun Jun 05, 2005 10:16 pm

Well, it's been doing this for about a week now... anyone have any idea? It's getting pretty gnarly sounding.

Dax · Post by **Dax** » Sun Jun 05, 2005 10:30 pm

Can you maybe get a longer clip of it? It sounds like a kick drum to me.

Dax

Eric Klinger · Post by **Eric Klinger** » Mon Jun 06, 2005 12:07 am

Will do... thanks Dax.

Flames1950 · Post by **Flames1950** » Mon Jun 06, 2005 12:15 am

So if changing the tubes only makes a difference for a short time, maybe it's something as simple as needing to clean the tube sockets? Inserting a new tube may make a clean connection for a brief time until the amp gets a chance to sit. And running it for a few minutes may get the connection going again as well, with a lovely crackle in the meantime.
Where is the amp being stored? It's not a humid environment is it? (Aka not a basement that stays humid?)

Eric Klinger · Post by **Eric Klinger** » Mon Jun 06, 2005 12:58 am

Thanks for the reply, Flames. Although it is super humid here is PGH at the moent (and only 80 degress) - it is in a "finished" basement hanging upside down on it's stand that I use for repair/mods, and it is not humid there at all... it's quite cool, but I will soon need to start the dehumidifier...

I will clean the sockets tomorrow and see what goes.

Thanks
Eric

Eric Klinger · Post by **Eric Klinger** » Mon Jun 06, 2005 9:09 pm

Didn't get a chance to clean the sockets out as of yet....

here's a longer clip of the noise... The noise fades in as I flip the standby, you can hear me plug my guitar into my EQ pedal, hit a couple of quick chords, unplug the the guitar from the eq pedal, and it will fade out after I hit standby. Strange. BTW it does this with no input to the amp as well, ruling out all cables, EQ pedal, and guitars.

http://www.digitalsoundplanet.com/Membe ... 028530.mp3

Thanks

Guitarcrazy · Post by **Guitarcrazy** » Tue Jun 07, 2005 12:45 pm

Question for you: did you replace the wires at the same time as the board replacement? I ask this question, because when I replaced my board - I didn't. I found a bad solder joint (cold joint ... factory) on V1 on one of the cathode connections. Use a chopstick .. and be very carefull ... to probe your wires. If you're getting a microphonic sound ... could be a bad solder joint.

Just my experience.

DonM

Eric Klinger · Post by **Eric Klinger** » Tue Jun 07, 2005 9:25 pm

Most of them... ones I did not replace are the red wires to pins 3 on the output sockets and pins 4-5 on the pres and the black wires going to 7 on the power tube sockets and 9 on the pre sockets... the blue wires from the indicator light... that was about it, all others were replaced.

I changed speaker cables and it still does it.

Guess I'll probe around with a pencil.

Crap! Forgot to clean the sockets again!!!

Guest · Post by **Guest** » Sat Jun 18, 2005 2:14 pm

Eric, I had a similar situation with a JCM800..Based on the last clip you posted it sounds almost identical to what my head was doing..after tinkering i think i narrowed it down the PI tube/socket. After cleaning it i ended up "tightening" the socket connections and the problem seemed to go away. Could be anything i guess but I'm with flames about checking/cleaning the sockets..wouldn't hurt to clean the pots as well

Metropoulos Forum

strange noise - link to 50kb audio clip inside (mp3)

strange noise - link to 50kb audio clip inside (mp3)

Re: strange noise - link to 50kb audio clip inside (mp3)