FDP Home Page / FDP Forum / FAQ's

The FDP is made possible by the following companies and individual members like you.
Please use the links below to show them we value their sponsorship.

MOD KITS DIY

Jensen Loudspeakers

WD Music

Musician's Friend

Antique Electronics Supply

Sweetwater

Apex Tube Matching

Amplified Parts

Yellowjackets Tube Converters

Amazon

Guitar Center


* God bless America and our men and women in uniform *

* Illegitimi non carborundum! *

If you benefit and learn from the FDP and enjoy our site, please help support us and become a Contributing Member or make a Donation today! The FDP counts on YOU to help keep the site going with an annual contribution. It's quick and easy with PayPal. Please do it TODAY!

Chris Greene, Host & Founder

LOST YOUR PASSWORD?

......................................................................

   
FDP Jam
Calendar
Find musicians
in your area!
  Search the Forums  

FDP Forum / Amp Mods, Repairs, and Projects / Weak Tremolo

orrk01
Contributing Member
********

USA / Saint Paul, MN

Sep 18th, 2016 06:36 PM   Edit   Profile   Print Topic   Search Topic

I have a Weber 6A14 Amp that I purchased from another forum member around 2008. Up until recently, the amp worked well in all respects. However, the tremolo has recently lost its zing. If I turn the intensity to 10, I barely get any tremolo effect.

I'm not the type to tinker with the innards of an amp because I know it can be dangerous and I have no electronics background. I replaced the V4 12AX7 tube to see if that would make a difference but it didn't improve at all. Due to the age of the amp, I suppose it could be due for new caps and a thorough going-over by an amp tech. Short of that, is there anything else I can do to troubleshoot this?

willie
Contributing Member
*******

Too Near Atlanta GA

Amp Tech Emeritus
Sep 18th, 2016 08:01 PM   Edit   Profile   Print Topic   Search Topic

A few possible causes. You might first replace V4 (12AX7)...or swap v3 and v4 to see if you have any change. Then you might have a bad cap at C9, C10, or C11 (.01, .01, .022), or a cathode issue on V4 with the 3.3K resistor or the 25uF cathode cap across it.

The 6A14 uses modulating bias type vibrato.

willie

orrk01
Contributing Member
********

USA / Saint Paul, MN

Sep 19th, 2016 05:14 AM   Edit   Profile   Print Topic   Search Topic

Thanks Willie.

Since I already tried replacing V4 with no effect, it sounds like it's off to the amp tech to check the other things you pointed out.

willie
Contributing Member
*******

Too Near Atlanta GA

Amp Tech Emeritus
Sep 20th, 2016 06:36 AM   Edit   Profile   Print Topic   Search Topic

Yep...pretty simple fix though for a tech that has any experience with this type of circuit.

w

orrk01
Contributing Member
********

USA / Saint Paul, MN

Sep 24th, 2016 08:25 AM   Edit   Profile   Print Topic   Search Topic

As long as I'm having work performed on this amp, let me ask another question. I have always wanted the tremolo to operate at a slower speed on this amp. I have seen mods suggested on various sites to slow down the trem and to make it more lush.

Suggestions are to add a .01uF/400V cap to C9 and C10 and/or to change the R51 resistor from 1M Ohm to something between 220K - 500K.

What do you all think?

pdf64

UK

Sep 25th, 2016 03:27 AM   Edit   Profile   Print Topic   Search Topic

R51 value affects trem depth, reduce it for deeper modulation. Not sure how that will affect its lush factor :-)
Increase the value of any of C9-C11 to get a the trem freq to a lower range. So yes, put another 10nF in parallel with one of them to slow it down a bit.
It's beneficial to include a link to a schematic if a post is referencing it.

6a14 schematic

(This message was last edited by pdf64 at 10:06 AM, Sep 25th, 2016)

FDP Forum / Amp Mods, Repairs, and Projects / Weak Tremolo




Reply to this Topic
Display my email address             Lost your password?
Your Message:
Link Address (URL):
Link Title:




Moderators: Chris Greene  Iron Man  reverendrob  

FDP, LLC Privacy Policy: Your real name, username, and email
are held in confidence and not disclosed to any third parties, sold, or
used for anything other than FDP Forum registration unless you specifically authorize disclosure.

Furtkamp.com 
Internet Application Development

Copyright © 1999-2017 Fender Discussion Page, LLC   All Rights Reserved