Bare Knuckle Pickups Forum

Forum Ringside => Tech => Topic started by: tomjackson on May 21, 2010, 10:53:22 AM

Title: Amp loud but with fizzy decay
Post by: tomjackson on May 21, 2010, 10:53:22 AM

Just borrowed an Blues Deville for a gig tonight, just cranked it, it's loud but if you strum and let it ring it kind of fizzes away.

I presume that would be something to do with the power valves?  I've swapped two of the preamp vales (on the RHS as you look at the amp from the back) to see if it was V1 but the problem is the same.  I'll try moving them round to V3 as well just to make sure it is none of the preamp valves.

any ideas?

Title: Re: Amp loud but with fizzy decay
Post by: Twinfan on May 21, 2010, 11:15:51 AM

Is that on the gain channel?

If so, there's some solid state clipping in there, which may explain the tonal character...

Title: Re: Amp loud but with fizzy decay
Post by: tomjackson on May 21, 2010, 11:57:04 AM

Both Channels, It's definitely a 'not supposed to be there fizz'

Title: Re: Amp loud but with fizzy decay
Post by: Twinfan on May 21, 2010, 02:00:11 PM

Gotcha.

Other than valve swapping, I can't help.  Sorry!  :lol:

Title: Re: Amp loud but with fizzy decay
Post by: HTH AMPS on May 21, 2010, 02:53:44 PM

could be a speaker on the way out - have you tried another speaker?

btw, I can't see any solid state clipping in the schematic of the Blues Deville - there are opamps, but they're part of the switching circuit and to drive the reverb.

Title: Re: Amp loud but with fizzy decay
Post by: Twinfan on May 21, 2010, 03:13:06 PM

Sorry - I'm thinking of the Hot Rod Deluxe I think  :oops:

Title: Re: Amp loud but with fizzy decay
Post by: HTH AMPS on May 21, 2010, 05:43:45 PM

Quote from: Twinfan on May 21, 2010, 03:13:06 PM

Sorry - I'm thinking of the Hot Rod Deluxe I think  :oops:

That one ain't got any diode clipping in either - all valve mate.  The Deluxe and Deville amps are very similar they just bypass a gain stage and re-configure other parts of the circuit's gain to go between clean and OD.

I'm not sure that Fender use any diode clipping in their 'all valve' amps - the hybrid stuff probably does (not that diode clipping is a bad thing, tube screamer anyone?)

btw, while you're here Dave, where did you get that pinup girl sticker/transfer for your blue Tele? - I've succumbed to getting one for my Tele  :D

Title: Re: Amp loud but with fizzy decay
Post by: tomjackson on May 22, 2010, 10:28:45 AM

Quote from: HTH AMPS on May 21, 2010, 02:53:44 PM

could be a speaker on the way out - have you tried another speaker?

btw, I can't see any solid state clipping in the schematic of the Blues Deville - there are opamps, but they're part of the switching circuit and to drive the reverb.

Spot on, it was the top left speaker, noticed it last night at the gig.  Once it was loud the other three overpowered it but I'll sort another speaker out so it doesn't damage anything!

Title: Re: Amp loud but with fizzy decay
Post by: Twinfan on May 22, 2010, 12:03:59 PM

Quote from: HTH AMPS on May 21, 2010, 05:43:45 PM

Quote from: Twinfan on May 21, 2010, 03:13:06 PM

Sorry - I'm thinking of the Hot Rod Deluxe I think  :oops:

That one ain't got any diode clipping in either - all valve mate.  The Deluxe and Deville amps are very similar they just bypass a gain stage and re-configure other parts of the circuit's gain to go between clean and OD.

I'm not sure that Fender use any diode clipping in their 'all valve' amps - the hybrid stuff probably does (not that diode clipping is a bad thing, tube screamer anyone?)

btw, while you're here Dave, where did you get that pinup girl sticker/transfer for your blue Tele? - I've succumbed to getting one for my Tele  :D

I thought the Hot Rods had diode clipping?  Must be dreaming!

I got the pinup girl from the dude on eBay you're looking at  ;)