5998 buzzing

[guildenstern]

Just received Crack with Speedball, nicely assembled by a gent on head-fi. Came with stock 12au7 supplied by BH (brand unknown, lettering worn off), a Tungsram E80CC, stock GE 6080, and RCA 6AS7G (coke bottle style). I have not used the E80CC. With 12au7 and either the GE 6080 or RCA 6AS7G, the amp sounds fine. However, I swapped in a Tung Sol / Chatham 5998 and, whoa, extremely loud buzzing. I happen to have four of these 5998 tubes (two I use in a Woo amp, two backups), and with all four tubes, the Crack buzzes like crazy -- the kind of noise that makes you rush to turn it off. I tried three different headphones just to be sure.

Searching the forums, I came across a thread about buzzing noises and other problems caused by some defective transistors in a batch of Speedball kits. One member specifically mentions that by replacing the bad MJE350 transistors, his Crack with 5998 went from "crazy humtastic" to "dead silent." See Reply #110 here:

http://bottlehead.com/smf/index.php/topic,6039.105.html

So, does it sound like bad MJE350 transistors might be the likely culprit in the Crack I bought? (The previous owner says he built it "less than 4 months" ago.)

Thanks for any help and advice you can offer.

[Paul Birkeland]

Built 4 months ago doesn't exactly specify when he may have bought and received the Speedball.

Can you post a photo of the MJE350's on the small PC boards? (both sides)

-PB

[guildenstern]

Built 4 months ago doesn't exactly specify when he may have bought and received the Speedball.

Can you post a photo of the MJE350's on the small PC boards? (both sides)

-PB

Thanks for the reply. I have an e-mail out to the original builder asking for the specific dates when he bought and received the Speedball. Here are the photos you asked for:

[Paul Birkeland]

Those are indeed the defective MJE-350's.  (Well, the print says MJE-350, but they measure out to be a completely different transistor, so counterfeit?)

[guildenstern]

Those are indeed the defective MJE-350's.  (Well, the print says MJE-350, but they measure out to be a completely different transistor, so counterfeit?)

Thanks for confirming my suspicion. My bad luck in buying an amp that happened to have the bad parts.