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Post subject: Vibrato intensity
Posted: Sat May 07, 2011 6:06 am
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Aspiring Musician
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My deluxe reverb does not seem to have alot of intensity on it vibrato.I get vibrato but not as strong as my vibrolux.

So i cleaned the pots and it made no difference,checked the resistance on them and they are in specs.I checked all the voltages and they are right. I put a piece of electrical tape over the roach and it made an improvement.So i replaced the roach.but it's still not as strong. I checked tubes with know good ones. i changed the cathode cap. when i did a cap job. But the amps vibrato was never that strong. I think i might lower the amps bias i am running it right now at 19.5mA at 432 volts using 12 watt tubes to 18mA i need to change the filter caps they are 20uF and i know the stock are 16uf would that have anything to do with it? I think it still might be the intensity pot? any thoughts?


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Post subject: Re: Vibrato intensity
Posted: Sat May 07, 2011 9:26 am
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The idle bias will likely have no effect on the trem performance (unlike the Champs and Princetons, with their bias-modulated trem). As well, the 20uF filter caps in the P/S are not an issue. I'm betting there's an out-of-spec resistor or a cap with DC leakage somewhere in the RC network at V5.

HTH

Arjay

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Post subject: Re: Vibrato intensity
Posted: Sat May 07, 2011 9:53 am
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I have one (well, three really) suggestions. There are three mica caps in a row, in the vibrato stage of most BF & SF Fenders. When I've checked all other components within this part of circuit & they teset out ok... I try changing out these caps.

I use 1KV rated discs, usually, for the 0.01 mfd caps and maybe an Orange Drop or Black Beauty for the 0.02 mfd cap (highest voltage rating you can get... 600 VDC is fine). Now, it'll take a bit of time for the caps to break-in. But, you notice (hopefully), a deeper, more adjustable vibrato section. Break-in can be a week... if you play the amp a couple of hours everyday. Or a month... if you play only on weekends.

See the lower portion of link, for layout:

http://www.ampwares.com/schematics/delu ... _ab763.pdf

See the 0.02mfd/600VDC OD and two 1KV caps in the VC just restored? Prolly improved the vibrato, at least 25% over OEM stock.

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Good luck with the fix! And have great weekend.


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Post subject: Re: Vibrato intensity
Posted: Sat May 07, 2011 1:18 pm
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Aspiring Musician
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well i found that pin one has about 430 volts on it way too high.So i am thinking about changing the 3 caps also i noticed that on pin 3 that the 2.7k resistor is reading 3.3k and that most of the resistors are reading higher then what they are supposed too


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Post subject: Re: Vibrato intensity
Posted: Sat May 07, 2011 3:16 pm
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Component drift is quite common among amps of this age -- I'd change out the most serious offenders.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Vibrato intensity
Posted: Mon May 09, 2011 3:45 pm
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I replaced a weak circuit on my bandmaster with the Surf Bug from tonecraft. Night and day difference.

Surf Bug is no longer available from Tonecraft, but the Black Widow is from these folks:
http://www.austinamplifier.com/services.html

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'59? Bogen Challenger CHA-33, '65 Bandmaster, '65 Tremolux, 65 Showman;
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Post subject: Re: Vibrato intensity
Posted: Mon May 30, 2011 1:26 pm
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Aspiring Musician
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Joined: Fri Dec 12, 2008 5:32 pm
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Retroverbial wrote:
The idle bias will likely have no effect on the trem performance (unlike the Champs and Princetons, with their bias-modulated trem). As well, the 20uF filter caps in the P/S are not an issue. I'm betting there's an out-of-spec resistor or a cap with DC leakage somewhere in the RC network at V5.

HTH

Arjay
Well guess what i changed to the stock value,and surprise,surprise i have a fuller deeper vibrato. Just remember everything effects something in an amp


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