Funny Buzz at Certain Frequency

Steve Feldman · Post by **Steve Feldman** » 19 Mar 2001 2:48 pm

Hello amp gurus -

I have a Fender Blues Deluxe that recently started giving me a slight buzz/hum only when a fairly narrow frequency range is played (e.g., playing 1st 3 frets on the low E string of my Tele). Almost sounds like the cone has a slight tear or something.

When I tried to reproduce this using the steel, I had no problem - no buzz. I went considerably lower in the register to try to make the thing buzz, but nothing. It occurs to me now though, that I DID NOT specifically try to reproduce the buzz using the same frequency as I did with the Tele.

Could it be that there is something whacked out with a tube or with the cone that only ocurrs within a narrow frequency range?

Thanks much for any advice, humor, whatever you've got...

Jim Eaton · Post by **Jim Eaton** » 19 Mar 2001 4:39 pm

It could be a loose piece of trim someplace on the cabnet. I use to have an old Twin reverb that had a funny buzz that turned out to be the twin reverb logo badge on the grill cloth that was buzzing.
JE:-)>

Steve Feldman · Post by **Steve Feldman** » 20 Mar 2001 6:28 am

This buzz happens only when the guitar is plugged in and not the steel. I'm stumped.

Scott Swartz · Post by **Scott Swartz** » 20 Mar 2001 9:25 am

Try it with a alternate speaker cabinet or connect to the speaker of another combo amp.

This will determine if it is speaker/cabinet related or electronic related, ie a frequency dependent oscillation in the amp circuit.

The PC board construction and the interconnects in these amps can also give vibration related intermittents that can cause all sorts of crazy behavior.

Scott Swartz · Post by **Scott Swartz** » 20 Mar 2001 9:28 am

Another thing, maybe its the guitar and you're hearing fret buzz. It may be time for a truss rod adjustment.

Try a different guitar.

P Gleespen · Post by **P Gleespen** » 20 Mar 2001 12:30 pm

I think I have some sort of "comedy dyslexia" because everytime I see the topic title, I think it says "Fuzzy Bunny".

If you put your ear on the neck of your tele (not plugged in) do you hear this buzz? I had a Fender Jazz bass with a wierd buzz that was caused by a damaged truss rod inside the neck.
Just a thought. I really just wanted to type "Fuzzy Bunny".

Steve Feldman · Post by **Steve Feldman** » 20 Mar 2001 2:26 pm

I think it says 'Fuzzy Bunny'

No - that's my OTHER amp...

Anyway - thanks for the suggestions. I know it's not the guitar, not fret bunny, but I think swapping out the speaker makes sense.

Thanks for the input.[This message was edited by Steve Feldman on 20 March 2001 at 02:26 PM.]

Steve Feldman · Post by **Steve Feldman** » 22 Mar 2001 6:37 am

OK - I figured it out. Now, what to do about it....

It only happens when I am in the 'drive' channel. The clean channel is OK. So, now, what does this mean? Bad tube? It's got 2 6L6s (I think) and I don't know about the preamp tubes.

Any ideas appreciated.

Thanks to all you Fuzz Busters out there.
SF.
[This message was edited by Steve Feldman on 22 March 2001 at 06:38 AM.]

Scott Swartz · Post by **Scott Swartz** » 22 Mar 2001 1:43 pm

Here's a schematic for your amp
http://blueguitar.org/bldlxsch.gif

You could try substituting V1 and V2 with different 12AX7s but the oscillation could be caused by lots of other things

Smiley Roberts · Post by **Smiley Roberts** » 23 Mar 2001 6:30 am

If it were an Evans amp, I guess it would be a "Buzz Evans".He,certainly,is a "funny Buzz!(nyuk,nyuk!)

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[This message was edited by Smiley Roberts on 23 March 2001 at 06:32 AM.]

Sage · Post by **Sage** » 23 Mar 2001 6:08 pm

Welcome the fuzzy bunny- Neaster is ear!

Steve Feldman · Post by **Steve Feldman** » 24 Mar 2001 8:38 am

I swapped out (switched) the preamp tubes and that resolved 80% of the problem. I guess I gots a bad tube, huh? Where do I get a hold of a couple of new 12ax7 tubes; what kind do I need; and does anything extra have to be done besides just plugging these guys in (e.g., power tubes require re-biasing, etc, right?).

BTW - thanks for the schematics link, Scott.

Thanks.

Rich Gibson · Post by **Rich Gibson** » 24 Mar 2001 10:47 am

Hi Steve.New preamp tubes don't require a re-bias-just slap 'em in.12AX7's are available at any well stocked music store or Musicians friend etc.As far types,there's basically Russian or Chinese that fall under a number of different brands.Most people seem to prefer Russian,although I don't if I could pass a blindfold test.Electroharmonix is also selling a "new" one that claims to be better suited to the high plate voltage of fender amps.Or,if you really want to go over the top you can pay a premium price and go with new old stock American or German.Some people swear by these,more so for power tubes,but preamps as well.In this case we're not talking about a vintage amp ,so the value of this route is dubious...hope this helps.By the way I love the send more hookers thing.

Rich Gibson

Steve Feldman · Post by **Steve Feldman** » 24 Mar 2001 2:16 pm

Thanks again, guys. I'll get me a couple of tubes and slap 'em in there. Bill - I'm not looking for headroom (if that's what you mean by 'standing tall'). This is just a sweet little tweed amp with a nice bluesy overdrive sound - perfect for playing with the Tele. And Rich, about that hookers thing...what can I say...let's just call it a funny socialogical phenomenon when you can live somewhere and go get all your 'errands' done in just one simple trip to town. That is, if you had a mind to.....

Jerry Erickson · Post by **Jerry Erickson** » 25 Mar 2001 9:13 am

Hi Steve,
Bunny fuzz eh? Hope it's not pink ! For tubes
check out triode electronics or Lord Valve.
Triode's in Chicago and Lord Valve(formerly "Fat Willie")of NBS can help you out. Willie probably has a preamp cocktail already prescribed for that amp.
Good Luck,
Jerry