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DV 336SE hum-Fitz mod?

post #1 of 49
Thread Starter 
I have a near new DV 336SE, 100 hours of use. I have a small collection of good testing 6sn7 tubes, some hum and others don't. I would like to do the Fitz mod, if someone can point me to the origianl post of how to do the mod I would appreciate it. I've searched several times with several terms , but nothing comes up.

Any help appreciated.

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post #2 of 49
I'm surprised the new DV 336SE still has a hum problem. I wonder why they haven't modified the new model?
post #3 of 49
Mine doesn't hum.
post #4 of 49
Thread Starter 
Mine hums only with certain tubes, out of about a dozen 6sn7's, I have 5 that don't hum and 7 or so that do. I'd like to try some of the Ken Rad black glass tubes I have, but they hum.

The easiest thing to do is just use the tubes that don't hum, right?
post #5 of 49
So far my experience is the same - some 6SN7's hum, some don't. And tubes that do NOT hum in other amps do hum in the 336SE. But I have some nice 6SN7GTB's that are completely quiet, including the very nice tall-bottle Tung Sols (vintage NOT re-issue), so I use that.
post #6 of 49
I think this is what you're looking for.

If for some reason the link doesn't work search tha336fm.

Roger



Quote:
Originally Posted by manfred77 View Post
I have a near new DV 336SE, 100 hours of use. I have a small collection of good testing 6sn7 tubes, some hum and others don't. I would like to do the Fitz mod, if someone can point me to the origianl post of how to do the mod I would appreciate it. I've searched several times with several terms , but nothing comes up.

Any help appreciated.
post #7 of 49
Does anyone know of a step by step guide for a noob to do this mod? In the original thread Fitz just explains basically what the mod is, not where to solder or part numbers to order.
post #8 of 49
Scooter, all you need is a pair of 100uF caps of your choice. Fitz said the voltage rating doesn't really matter, so choose whichever cap you want.
post #9 of 49
I'm curious to know if other peoples experience mimics mine.

I've found that it's just a matter of time before the hum goes away.

Most tubes that hum took a couple of hours, but I had a grey glass RCA that took a couple of days for the hum to dissapear.
post #10 of 49
In general, but it seems that is not always the case.
post #11 of 49
Quote:
Originally Posted by scootermafia View Post
Does anyone know of a step by step guide for a noob to do this mod? In the original thread Fitz just explains basically what the mod is, not where to solder or part numbers to order.
Make sure you test various caps around the circuit after powering it down for a few hours to make sure no lethal voltages exist across the circuit.
post #12 of 49
Ok, so 2x 100uf caps, any voltage. Anyone have any detailed information on where these guys go?
post #13 of 49
Search, and ye shall find
post #14 of 49
Quote:
Originally Posted by manfred77 View Post
Mine hums only with certain tubes, out of about a dozen 6sn7's, I have 5 that don't hum and 7 or so that do. I'd like to try some of the Ken Rad black glass tubes I have, but they hum.

The easiest thing to do is just use the tubes that don't hum, right?
Ken Rad's are hit or miss. A lot of people have issues with them humming. This is not isolated to the 336. My 336i would hum on certain tubes but I don't ever remember it lasting for longer than an hour or so with NOS tubes.

Silvertone, RCA (black base), Brimar CV1988 (favorite in the amp) never had a hum.
post #15 of 49
Heheh, I keep searching but finding the wrong threads. I've found Fitz's thread where he shows off all his 336 mods, but it doesn't have a step by step or something. There should be a sticked warning that the 336 hums and comes with a **** power switch.
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