help with noise at startup volume turned down

[Paul Birkeland]

A loose connection may measure just fine with your meter, but once you flip the chassis plate over, jiggle the plate, and plug in headphones, the connection may be compromised again.

Reheating all your solder joints is free, I'd give it a try before anything else.

 

[ghost_rider]

A loose connection may measure just fine with your meter, but once you flip the chassis plate over, jiggle the plate, and plug in headphones, the connection may be compromised again.

Reheating all your solder joints is free, I'd give it a try before anything else.

I did try poking all the connections with a lolly stick and none of them were loose. Still i will give it a try, just to be sure

 

[Hornet900]

I just tried a Brimar 12BH7 tube and its still got the noise at 0% volume, Amps been on for 30 mins  ???  And It sounds rubbish waste of money :'(

The Noise is maybe  a little louder with this tube and still touching my headphone cable changes the tone of the noise ;D...I've ordered a new HD650 cable should have it next week ..Cant see that fixing it as I've  tried another pair of headphones ....I  needed a new cable anyway.

But yesterday I had the amp on for a long time and it went silent at 0% volume after an hour or 2!  But still if I moved the headphone cable about it would come back ...
I could make it go silent though!

i also installed new headphone jack socket yesterday with no change.
Will have another 5998 on wednesday

 

[Paul Birkeland]

Try moving the ground wire leaving the headphone jack and heading to the volume pot so that it's not on top of the 9 pin socket.

 

[Hornet900]

Hello Paul thanks for the tip  I already rerouted that wire with my troubleshooting, I did rerouted that wire around the front like I've seen other  people do  their builds.
The amps been on for an hour now and its silent again at 0%.
Its must be something to do with the 5998 tubes I've had and I'm unlucky   

though it makes the noise with the other tubes at startup but goes much quicker with them  , With the mulllard 6080 it goes in 10 seconds 0% and the 2 RCA 6AS7G tubes it stays for a few mins then silent and the stock tube takes bit longer .
All the tubes make the same type of noise at startup even if the volume up but goes in 5 seconds max with the volume up.. just  turning the volume down the noise is there longer with different tubes and the 5998 takes the longest for it to go.

Its just messing with my cable thats freaking me out because the noise changes. ( it happens with all the tubes when the noise is there 0% playing with the cable)
And the really noisy 2399 tube I had with all volumes was ok when I uninstalled the speedball. 
Its Always the same type of noise.

I've ordered new parts for my amp and will be rebuilding it, but stupid me I've only got the parts for the stock crack but I'll see how I go with that 1st

Thanks...
Its still silent  ;D  sounds great  ;D

 

[Paul Birkeland]

I've ordered new parts for my amp and will be rebuilding it, but stupid me I've only got the parts for the stock crack but I'll see how I go with that 1st

What do you plan to do differently?

 

[Hornet900]

Nothing really    Just  reflowing all the joints made my amp look bit messy doesnt look as nice now :-*  and On the big power tube socket 1 of the solder tabs fell out the bottom when I  removed and replaced the wire. I soldered a little bit on it and put it back in , The big tube wont go all the way down now on 1 side,  I had the noise before I did this.
I've replaced loads of the wires  ;D....the little tube socket is  also bit wobbly now.

Mostly I want to polish both sides of the top plate and clean clear coat the bell housing
and I thinking about running the amp without the speedball for a while

Thanks 

I

 

[Hornet900]

Number 4  5998 tube  arrived.

Also has the noise at 0% volume,  amps been on 30 mins ... noise not gone away at 0% volume ...with the volume turned up past 5mm its silent. 
took about 2 mins to be dead silent with volume turned up..longer than my other 5998 tubes.

 

[Stanshall]

Just seen that this is mentioned elsewhere and is standard amplifier warm-up behaviour.

 

[tdubl07]

No, the zero volume hum never goes away that some of us are getting. Even after all day usage. I've resolved myself to never turn it that low and no issues.

 

[Adrian]

I can't believe that having a zero volume hum is a design feature.  I can understand it before full warm up (I guess) but not continuous.
Anyone out there who can help with what I hope is an issue that can be addressed and not a necessary "evil" we have to live with?

I'm about a month away from installing the Speedball and am very interested in what to expect.

 

[Paul Birkeland]

I can't believe that having a zero volume hum is a design feature.  I can understand it before full warm up (I guess) but not continuous.

Yeah, it's been a little tough to sort out whether it is persistent in all cases, or goes away after the amp warms up. This is not a design feature, and has just popped up recently.  We are looking into this currently. 

 

[Adrian]

PB:  Thanks. I'm confident the Bottlehead family will not settle for mediocrity.

 

[Hornet900]

YEEHAW GUYS!!  I've solved my noise problem!!
I replaced all the parts on both the two small A & B boards and now my amp is dead silent!!!!
I have not even a warm up noise now no buzzing nothing. All my tubes are perfect.
These are the parts I used guys
2 X TE CONNECTIVITY / NEOHM - YR1B237RCC - RESISTOR, METAL FILM, 237R, 250MW, 0.1%
2 x STMICROELECTRONICS - 2N2907A - TRANSISTORS
2 x MJE350 High Voltage PNP Power Transistor
4 x HLMP-6000 Avago Technologies LED, Submin, Red.
I never replaced the 150k 2w resistors.
Question  though : Are the 237R resistors I used ok ?
also the  2N2907A transistors I used were a different make then old ones.
Is this ok? I've not done a voltage check yet.

 

[Paul Birkeland]

Yeah, those 237 Ohm resistors look like they are equivalent to what we supply, though we generally use 1/8 Watt parts.

 

[Hornet900]

great Paul thank you    happy bunny now 

 

[Doc B]

We have worked out what is happening. PB will be pulling the divergent threads about this together and posting instructions. Basically the last batch of MJE350s we purchased has some that are out of spec. We have some in spec replacements on order and we will be able to supply them to anyone who has experienced the problem. It seems to be isolated to a few Speedball kits shipped in the past month or so, and if your kit is working fine the MJE350s should not be replaced.

 

[Hornet900]

Its working great now thank you   

 

[Paul Birkeland]

OK, I think I have all the relevant threads merged here.

Essentially, we have been working with a supplier for quite some time now who offered the ON Semiconductor MJE-350 at a reasonable price when bought in bulk.  We had been purchasing bulk lots for quite some time, with great results, but the last batch we received were from a different manufacturer that we are not familiar with.  Unfortunately, the supplier did not notify us that they made this substitution. 

To that effect, some MJE-350's in recent Speedball kits may produce this defect where hum is encountered at 0 volume level.  To remedy this situation, we can offer a replacement pair of MJE-350's.  If your Speedball does not exhibit these symptoms, you would not want or need to replace these transistors. 

If you are in a hurry to patch this up, you can purchase MJE-350's from your favorite local seller.  A Motorola, ON Semiconductor, ST Microelectronics, Fairchild, Texas Instruments, or even an NTE-39 are going to work great!  For those who have Speedballs or other kits using MJE-350's on order, we will not be putting these parts in your kits. 

We do appreciate all of you letting us know that this was an issue, giving us some time to determine the nature of the problem, and we look forward to providing assistance to remedy this issue.

-PB

 

[pduk]

Hi Paul,

Any difference between the MJE350 and MJE350G?

Thanks

(another) Paul.