help with noise at startup volume turned down

[jboehle]

Finished assembly of my Speedball boards and got them installed tonight.  Unfortunately I am having this exact issue.  Just emailed for replacement parts.  Thanks for persevering and figuring this out, Paul!

[pduk]

I got my two replacement transistors yesterday (via ebay as I am impatient). Just fitted them and I'm delighted to report that the symptoms are completely gone now. Good job tracking it down - thank you.

Now waiting for that 5998 that I accidentally ordered last week to arrive from the USA

All the best

Paul.

[Hornet900]

Good to hear Paul    I also got my 5998 tubes fromthe  USA bit pricey tho, I payed £80! for one and also had to pay £20 for customs    very expensive but i managed to buy another 2 tungsol 5998 for £90 delivered with no customs charges   enjoy the 5998 tube best one I've tried so far
I'm trying a telefunken e80cc with the 5998 and its very good

[tdubl07]

This is great news guys. Glad the gang figured it out. I ordered four new transistors from digikey for about 5$ shipped. Seems like digikey had the only first class mail option. Mouser min is 6.99$ on shipping. For anyone else thinking about ordering some. I'll have mine swapped tomorrow night.

[jboehle]

Bottlehead, when do you estimate the replacement MJE350 parts will ship?

[tdubl07]

Another successful transistor swap. No buzz at zero volume. Thanks guys. For anyone not too sure with desoldering the old ones, it's most helpful and much easier to cut the old ones off and then unsolder each leftover leg via one by one. If you don't have some solder wick and a desolder pump now would be a great time to order some so you're ready when the new transistors come in. Good luck, glad we have a fix edit.... I just tried my 5998 that I thought was noisy (it was crazy humtastic on the bad transistors) and no hum at all and dead silent with the new mje350s. So maybe this was the fix for those of us who had really noisy tubes as well with the bad transistors. Time will tell as I just quickly checked but promising so far.

[jboehle]

I replaced my bad MJE350 parts today with MJE5731AG parts I got from Digi-Key, and all is well!  Nice and silent and the Crack + Speedball sounds amazing!

Are there any other parts I should change to go along with the MJE5731AG, or does it work perfect as a drop-in replacement?

My voltage checks with the MJE5731AG went perfect.

[Paul Birkeland]

They are more or less interchangeable with the MJE350 in the C4S, provided they are flipped around. 

[jboehle]

Thanks PB!  Yes, I triple-checked the pin-out on the datasheet matched the B-C-E labeling on the PCB before soldering them down.   

[Strikkflypilot]

Hi. I have this issue with the tune that came with the amp, a 6080WA.
With an RCA 6080 no issues.
Who do I send an email to, to get replacement MJEs?

[jboehle]

replacementparts at bottlehead dot com

[Strikkflypilot]

Thanks

[Adrian]

Speedball installed successfully, but I've got these symptoms -  buzzing at startup and zero volume position, goes away after a short while and doesn't come back (yet!).  I need to get new MJEs.

[Strikkflypilot]

Hi Adrian.

Had the same questions. Was at first very surprised at how much the Speedball alters the Crack.
Bottom line, as long as noise, whether it be a buzz or other, it should fade out and disappear when the tubes are hot.

Personally, I wouldnt change Your MJEs if the buzz is gone after a minute or so.

I had the buzzing issue, wouldnt go away on my stock tube. I swapped to a microcomp MJE on both channels. Now I also have a buzz on startup but fades away, meaning its good.

[Adrian]

"PB" / Doc:  For clarity:

• If I have this buzzing at zero volume on the pot and it goes away shortly after startup, should I bother with changeout of the MJEs?
• If the MJEs were from the "bad batch" would the buzzing subside shortly after warmup?
• If I install GOOD MJEs will I have any buzzing - still at startup?
• Did BH have any buzzing problems prior to the discovery of the BAD MJEs?
• If not, then shouldn't these be replaced if any buzzing occurs?
I would like this amp to be like a graveyard on a moonless night - DEAD QUIET - like before the Speedball Install.