help with noise at startup volume turned down

[Paul Birkeland]

You can try running a 12BH7 in the 9 pin socket to see if those conditions remove the noise.

[hibitec]

I have the exact same issue and I'm using the stock 6080 that came with my kit. My build is still completely stock.

Before I installed the Speedball, the amp was dead quiet at lowest volume when first powered up. With the Speedball, it has a loud hum and pops during the first few mm of a turn until the tubes warm up - about 2 minutes. All my voltages checked in range. What is it about the Speedball that makes this happen? My biggest fear is damage to my headphones. I can, of course, work around it but it would nice if there was a solution so I would not have to worry about it.

[Doc B.]

I was able to reproduce this start up phenomenon once on Saturday, but only with the volume turned all the way down. Which leads one to think that maybe leaving the volume up just a bit from all the way down will be a good idea until we can come up with a reasonable explanation for what is happening.

[tdubl07]

Yep, I as well have had the zero volume hum since my build a couple weeks ago(w speedball) and I replaced the pot with a PEC just to make sure it wasn't that, and that didn't fix the zero volume hum, so my solution is to never turn it to zero volume.  Anytime you return the pot to zero volume no matter if the amp has been on all day, the hum is still there. Past zero the amp is dead silent and rocks as usual. I would also like to chime in and say my TungSol 5998 I ordered and installed was humming like crazy, even after warm up so I've taken it out and am just running the stock 6080. I also as a precaution leave my headphones unplugged at startup until the tubes have fully warmed up. Be interesting to see what you guys figure out what's causing this. Anyway no zero volume, done and done 

[Doc B.]

Very interesting that changing the pot made no difference. I was going to guess that the stock pot may have been part of the issue. Come to think of it the amp that made noise for me had a 5998 n it. so it is probably a tube issue as PJ described.

[hibitec]

As I posted, I have the same issue with the stock 6080 so it's not just the 5998.

[tdubl07]

Yeah I suspected it was a pot issue since day 1, so I ordered one and changed it and no difference. Interestingly enough my 6080 that came with the kit was arcing at startup so I ordered the 5998. Well the 5998 was humming like crazy at all volume levels (worse than the stock 6080) with the new PEC pot in. So I was a little disheartened. Thinking both tubes the stock 6080 (especially with the arcing issue) and the 5998 might be suspect, I ordered two more 6080's. Got them in and luckily one fixed the hum issue....all except the zero volume hum. More interesting however was that the other 6080 I received in hummed like crazy as well (all volume levels). So my conclusion for general hum (that doesn't change) relative to volume, it's quite possible that hum can be caused by a bad/noisy tube and to try a couple more to rule that out. I'm lucky I ordered two more as the one hummed worse or the same as my stock 6080. This is of course assuming all voltage/resistance checks are in spec before trying a new tube. And the zero volume level hum is present with both tubes (5998 and 6080), works flawlessly when off zero volume.

[Hornet900]

Well guys I just received 2 tung sol 5998 tubes from ebay advertised as "Never used Perfect condition" no test data with them...though tubes look brand new.
with these 2 tubes I only have the noise at 0% volume now  even if  the amps warmed up just like my stock RCA 6080 does. Turning the amps volume past 5mm the noise goes away.

I have a mullard 6080 that makes the noise for maybe 30 seconds at start up 0% volume then goes completley silent . I also have 2 RCA 6SA7G  tubes that take a little longer than the mullard but they go quite at 0% volume after a while.

My noise is louder in the left channel.

One thing is guys if I touch the headphone socket (not the top plate) the noise changes tone at the 0% volume...touching my fingers around the socket like I'm trying to cover it up makes the noise goes much quieter (an changes tone),  the noise is like a humming buzzy noise not touching the socket  then when I touch the socket it goes to more of a hum and quieter...
And also touching the headphone cable changes the noise but not as much as the socket does.

The noise does change even with the other tubes I have ..  But the mullard is best.

I've only 2 types  driver tube to test with the stock Hewlett Packard 5963 (12AU7) my Mullard CV491  ( I  have 2 more Hewlett packards so I'll try them  later  and report back.

Hope this helps

PS: I will be getting another 5998 tube in the next few days a Chatham 5998 so report back when i have it


Edit: My Mullard CV491 isn't broken , I tried it again and it works    Sounds brill

 

[tdubl07]

Well guys I just received 2 tung sol 5998 tubes from ebay advertised as "Never used Perfect condition" no test data with them...though tubes look brand new.
with these 2 tubes I only have the noise at 0% volume now  even if  the amps warmed up just like my stock RCA 6080 does. Turning the amps volume past 5mm the noise goes away.

I have a mullard 6080 that makes the noise for maybe 30 seconds at start up 0% volume then goes completley silent . I also have 2 RCA 6SA7G  tubes that take a little longer than the mullard but they go quite at 0% volume after a while.

My noise is louder in the left channel.

One thing is guys if I touch the headphone socket (not the top plate) the noise changes tone at the 0% volume...touching my fingers around the socket like I'm trying to cover it up makes the noise goes much quieter (an changes tone),  the noise is like a humming buzzy noise not touching the socket  then when I touch the socket it goes to more of a hum and quieter...
And also touching the headphone cable changes the noise but not as much as the socket does.

The noise does change even with the other tubes I have ..  But the mullard is best.

I've only 1 type of driver tube to test with the stock Hewlett Packard 5963 (12AU7) my Mullard CV491 broke the other day    ( I also have 2 more Hewlett packards so I'll try them  later  and report back.

Hope this helps

PS: I will be getting another 5998 tube in the next few days a Chatham 5998 so report back when i have it

Sweet, wonder if I should contact vacuumtubes.net and ask for a replacement for my 5998 that hums like crazy

[Hornet900]

I forgot to ad I changed the stock pot as well to a comos still the same,  I preferred the stock pot for sound 

[Hornet900]

Well guys I just received 2 tung sol 5998 tubes from ebay advertised as "Never used Perfect condition" no test data with them...though tubes look brand new.
with these 2 tubes I only have the noise at 0% volume now  even if  the amps warmed up just like my stock RCA 6080 does. Turning the amps volume past 5mm the noise goes away.

I have a mullard 6080 that makes the noise for maybe 30 seconds at start up 0% volume then goes completley silent . I also have 2 RCA 6SA7G  tubes that take a little longer than the mullard but they go quite at 0% volume after a while.

My noise is louder in the left channel.

One thing is guys if I touch the headphone socket (not the top plate) the noise changes tone at the 0% volume...touching my fingers around the socket like I'm trying to cover it up makes the noise goes much quieter (an changes tone),  the noise is like a humming buzzy noise not touching the socket  then when I touch the socket it goes to more of a hum and quieter...
And also touching the headphone cable changes the noise but not as much as the socket does.

The noise does change even with the other tubes I have ..  But the mullard is best.

I've only 1 type of driver tube to test with the stock Hewlett Packard 5963 (12AU7) my Mullard CV491 broke the other day    ( I also have 2 more Hewlett packards so I'll try them  later  and report back.

Hope this helps

PS: I will be getting another 5998 tube in the next few days a Chatham 5998 so report back when i have it

Sweet, wonder if I should contact vacuumtubes.net and ask for a replacement for my 5998 that hums like crazy

tdubl07 I just sent back a Chatham 2399 to vacuumtubes.net that made the noise at all volume , It worked fine 1st time i used it with the speedball.
without the speedball it worked fine  as I uninstalled the speedball to check 

[Doc B.]

tubes from ebay advertised as "Never used Perfect condition" no test data with them...though tubes look brand new.

How do they know they are in perfect condition if they have never been used? 

[Paul Birkeland]

One thing is guys if I touch the headphone socket (not the top plate) the noise changes tone at the 0% volume...touching my fingers around the socket like I'm trying to cover it up makes the noise goes much quieter (an changes tone),  the noise is like a humming buzzy noise not touching the socket  then when I touch the socket it goes to more of a hum and quieter...
And also touching the headphone cable changes the noise but not as much as the socket does.

This is a strong suggestion that the top plate is not well earthed.  The plate is earthed by the wire leaving "E" on the AC power inlet, which goes to the solder lug on the #8 screw.  If you have a floating/missing ground on your wall power, this might be something to look into.

[Hornet900]

Yes Sir Doc    They do sound great though and look brand new I payed £91 deliverd to the UK as a gamble on ebay with a seller with no feedback  . I knew new tubes can be bad . the glass is Like brand new very clean and look beautiful lit up.

Thanks Paul ,  I did redo that wire but nothing changed and double check everywhere else, reheated all joints.... Could the resistors on the headphone socket cause this ?
and I also I re wired and rerouted the Ground wire from the volume pot to headphone jack and 2 black wires at terminal 3 grounds , new wire from volume pot to the rca inputs.
I  will look into it  more

One thing I haven't tried is changing the transformer terminal 4 wire to 22L instead of 14U , I built the amp with the revision update connection to terminal 14U.

And I should add my amp is dead quiet without the speedball installed all tubes ,  No noise 0% volume...Even the chatham 2399 that buzzed at all volumes was ok no speedball 

 

[ghost_rider]

Hi everybody,

Sadly Easter break is over and I came back to my university for my semester. Wont go home for 3 more months and the Crack is back home  

I did have 3 tubes and all were brand new with a warranty from the tube store (30-60 days I think). Before the speedball they did sound great so Im confused if it was the tubes, and what are the odds of getting all 3 noisy tubes?

I will be getting some 12BH7s next time with me when I go home 3 months later as PJ advised. But in the meantime if somebody can please fix the issue that will be very very helpful

My hum was also more on the left side and less on the right. Not much happens if i poke the wires or hold the wires. I get 3 different tone of noise, 1 at the 0 volume to 7%, next one starts from 8% to 92% volume and the last one is at 93-100% volume. There are some poping sound when i cross the 7% mark. Also the hum is little more on the mid level. All of this is with the 5998s. All 3 of them

With the 6080WA i have a hum at 0-7% for first 3-4 mins and then its quite. I feel like I can hear some noise at for up till 20-30mins. a very low background noise. I m pretty sure this was not present in the crack. But it does go away after 30 mins of running.