fender deluxe homemade too bright and clean

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rutledj
Posts: 305
Joined: Sun Sep 17, 2006 2:08 am

fender deluxe homemade too bright and clean

Post by rutledj » Mon Apr 03, 2017 12:15 am

I have a fender deluxe that I built with a vibroverb style vibrato circuit. It has always been too bright and you can turn it all the way up and it stays clean. Not the expected breakup common with deluxe amps. I followed the typical ab763 layout. Open to any suggestions to give the amp some breakup much earlier and to tame the brightness.

Thanks,
Rut

tubeswell
Posts: 1977
Joined: Thu Mar 27, 2008 6:42 am
Location: Wellington. NZ

Re: fender deluxe homemade too bright and clean

Post by tubeswell » Mon Apr 03, 2017 12:38 am

Which 'Deluxe' is it?

And what are the voltages throughout the amp?
He who dies with the most tubes... wins

Stevem
Posts: 2066
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Location: N Y

Re: fender deluxe homemade too bright and clean

Post by Stevem » Mon Apr 03, 2017 10:46 am

The OP clearly stated he built it from a 60s blackface schematic!

If you built it like a black or silver fade Deluxe with a .47 of cap across the volume pot then remove that , as that is like having the brite switch always on like the other bigger Fender amps had.
This should knock out 90 percent of the excess high end!

If indeed you built this like a BF , or SF Deluxe then try out a 12ax7 in place of the 12at7 for the phase inverter tube.
Also unless your preamp tubes are tested and or known to be strong, a tube gone down to 57 % from what I concider a needed minimum of 84% will make for a big difference in the drive signal coming into and out of the PI section.
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tubeswell
Posts: 1977
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Location: Wellington. NZ

Re: fender deluxe homemade too bright and clean

Post by tubeswell » Mon Apr 03, 2017 6:54 pm

Stevem wrote:
Mon Apr 03, 2017 10:46 am
The OP clearly stated he built it from a 60s blackface schematic!
I missed that reference the 1st time around.

Agree about the bright cap.

Seeing the voltages will highlight how the stages work into each other w.r.t. to bias and headroom etc. Pre-amp supply node voltage might be too high.

Other factors like the OT Iron and the amount of NFB could affect this.
He who dies with the most tubes... wins

Firestorm
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Location: Connecticut

Re: fender deluxe homemade too bright and clean

Post by Firestorm » Tue Apr 04, 2017 5:12 pm

If this is a non-reverb Deluxe, you're missing the (small) gain of the reverb mix stage, which makes a difference especially considering the loading of the trem circuit. It's not as bad as the non-reverb Princeton, but it won't get up and dance around.

Stevem
Posts: 2066
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Location: N Y

Re: fender deluxe homemade too bright and clean

Post by Stevem » Thu Apr 06, 2017 10:42 am

Good points!
If I recall right the reverb mixer stage added another 12 db, and the Tremolo circuit sucked out some 6 db of that 12!
You can get thrown in jail in the US for hunting and fishing without a license, but it's just fine to come across our border without the proper immigration papers!

sixstringer
Posts: 173
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Location: SoCal

Re: fender deluxe homemade too bright and clean

Post by sixstringer » Mon Apr 10, 2017 6:41 pm

If you have 170v or more on the plates of the pre-amp tubes you could try dropping the voltage off the power rail at “B” so you get closer to 100v on those plates, that will brown up the amp and give you earlier breakup. Also, you could try changing the rectifier tube to a NOS tube and see as much as a 50v drop, that will also reduce headroom.

keewee
Posts: 43
Joined: Sun Sep 06, 2009 6:49 am

Re: fender deluxe homemade too bright and clean

Post by keewee » Tue Apr 11, 2017 9:22 pm

+1 on the bright cap 0.47 pf to 500 pf high pass, to your own taste. Leo designed this to be a clean amp, but can distort if stressed. +2 Leo.

pdf64
Posts: 1147
Joined: Sat Mar 12, 2011 9:23 pm
Location: Staffordshire, UK

Re: fender deluxe homemade too bright and clean

Post by pdf64 » Wed Apr 19, 2017 2:10 pm

rutledj wrote:
Mon Apr 03, 2017 12:15 am
I have a fender deluxe that I built with a vibroverb style vibrato circuit. It has always been too bright and you can turn it all the way up and it stays clean...
As it's not a clone, it may be helpful to show the actual schematic used and photos of the build.
Then everyone has the same reference point.

tictac
Posts: 521
Joined: Fri Mar 31, 2006 4:42 am

Re: fender deluxe homemade too bright and clean

Post by tictac » Fri Apr 21, 2017 3:25 pm

I've noticed on some newer Fender models made with pcb's they actually add a small value cap to ground in the signal path.

I'm thinking they do this to cut down the brightness of the tone. So in essence they are trying to mimic the capacitance of the older Fender's built with fiber board / eyelet construction.

The fiber board is known to have some capacitance and it's been commented on by experienced builders that have changed their amps builds to fiberboard they noticed a change in tone, an improvement

in their opinion.

Maybe you simply need to try some caps to ground in the signal path, say 1000 to 3000 pf just before the PI input is where I've seen Fender place them.....

This will definitely allow you to tune the brightness to your liking....

TT

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