[Teknofossil58]

I bought this amp used a couple months ago, seemingly in great shape. Due to my busy schedule I only yesterday got arround to hooking it up. Once warmed up for about 15 minutes I noticed a slight buzz/hum from both channels, though when playing music it was not a big deal. However, playing music something sounds not right. Almost a recessed vailed quality to the sound. I tried a number of different sources, CD (Oppo) phono and the effect was still there. I replaced the amp with my old Parasound amp and the qualities I noticed disappeared. I began to wonder if the 12AX7 tubes in the input stage might be tired so I opened up the amp to replace them (I have a large number of NOS tubes). Odd thing I noticed was (3 of the 4) 330uF 250v caps are missing the upper portions of the outer plastic jackets which were loose in the chassis (I set them on to of the power transformer). The tops of the caps aluminum casings do not appear ruptured though slightly bulged. I suspect these caps are related to the HV feeding the 12AX7's but I have not traced the circuit nor checked voltages. I'm wondering if this is tied to the noise / sound quality I have noticed. I have not swapped out the tubes or checked tested them (I own a B&K test set). An

y thoughts?

[Phil_S]

If it was me, I'd make arrangements to send it to Frank for evaluation & repair.

[ArthurDent]

At least give him a call and have a chat about it, if he doesn't notice the thread and respond here.

[WGH]

Looks like a trade-in to me. I like the sound of the new SET series better than the old FET.
What speakers are you using?

[charmerci]

FET 300? Isn't that like over 20 years old? I'd say put in good tubes first.


Though I should say that I'm no technician.

[I.Greyhound Fan]

Bulging caps are bad and should be replaced immediately.

[avahifi]

I suggest you replace the tubes first.

Call me at 651-330-9871 for more help.

Frank

[rcag_ils]

Bulging caps are bad and should be replaced immediately.

The top plastic fell off not due to bulging. I have caps did that and they work just fine and I did not see any bulging.

[avahifi_lj]

FYI:  It was very common to see the plastic top come off the large electrolytic capacitors back when this amp was built.  The capacitors had a heat shrink wrapper, and over the years the wrapper continues to shrink to a point where it pulls down the side of the cap.  You may find the black round plastic caps inside the amp.

Larry