. i was thinking of making it more like my super reverb. or maybe it won't work as well cause smaller OT and 2 less speakers... just curious if anyone had any thoughts.. thanks! 
raise filtering on blackface vibrolux ?
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hitchcaster
- Posts: 296
- Joined: Thu Jun 01, 2006 12:30 am
raise filtering on blackface vibrolux ?
anyone messed with raising the power supply caps on a blackface vibrolux? 16uf all around just seems so low! . i was thinking of making it more like my super reverb. or maybe it won't work as well cause smaller OT and 2 less speakers... just curious if anyone had any thoughts.. thanks!
. i was thinking of making it more like my super reverb. or maybe it won't work as well cause smaller OT and 2 less speakers... just curious if anyone had any thoughts.. thanks! -
Leo_Gnardo
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- Joined: Thu Sep 27, 2012 1:33 pm
- Location: Dogpatch-on-Hudson
Re: raise filtering on blackface vibrolux ?
The uF value of the filter caps in Fender amps had to do with two things mostly. 1) cost. At the time it was the most filtering you could get for the money. Sure they could have ordered higher values at higher prices, or doubled up as is done in some amps, but they were building to a price mostly. and B) how much hum can we get away with? More filter, less hum. Leo and his biz managers weren't necessarily out for minimum hum, the company needed to make money while keeping their amps at a competitive price, so back to #1. You rockers are supposed to play loud enough you won't hear the hum. Now 50 years later more or less we appreciate the extra quality Fender did build in, and there's no sin in improving them as necessary.
Of course you can increase your power supply filters. If using tube rectifier, I'd stop at say 47 to 60 uF for the first stage. Rectifier tubes will not get along with larger filters. Too much will shorten the rectifier's life. Solid state rectifiers, no problem with these values.
Another hint to minimize hum is to land the ground end of the filter serving the preamp tubes on the brass bus behind the pots. Amps that don't have one, on the chassis behind the pots. Some Fenders already have this feature. If yours doesn't, or if you have one of the amps with a multisection cap, consider doing it to minimize your hum.
A humdinger pot on the filament supply is another useful option.
I commonly increase the value of the filter caps to keep picky customers happy. Some are jazzers, others studio musicians with wide dynamic ranges, who really want to avoid any noises at all whether hum, hiss, pops chatters & squeeks.
Of course you can increase your power supply filters. If using tube rectifier, I'd stop at say 47 to 60 uF for the first stage. Rectifier tubes will not get along with larger filters. Too much will shorten the rectifier's life. Solid state rectifiers, no problem with these values.
Another hint to minimize hum is to land the ground end of the filter serving the preamp tubes on the brass bus behind the pots. Amps that don't have one, on the chassis behind the pots. Some Fenders already have this feature. If yours doesn't, or if you have one of the amps with a multisection cap, consider doing it to minimize your hum.
A humdinger pot on the filament supply is another useful option.
I commonly increase the value of the filter caps to keep picky customers happy. Some are jazzers, others studio musicians with wide dynamic ranges, who really want to avoid any noises at all whether hum, hiss, pops chatters & squeeks.
down technical blind alleys . . .
Re: raise filtering on blackface vibrolux ?
Very good, Leo.
And the consequences of higher filtering are...
Less power supply sag, thus "faster" or more revealing attack
Tighter bottom end, esp. good for bass amps
other?
And the consequences of higher filtering are...
Less power supply sag, thus "faster" or more revealing attack
Tighter bottom end, esp. good for bass amps
other?
I build and repair tube amps. http://amps.monkeymatic.com
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Leo_Gnardo
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- Joined: Thu Sep 27, 2012 1:33 pm
- Location: Dogpatch-on-Hudson
Re: raise filtering on blackface vibrolux ?
Less hum.xtian wrote:other?
Funny I was listening to a CD by local blues muso Scott Weis yesterday, he's not afraid to use the funkiest of amps to get his tones. Hum & buzz, he don't worry about. Gets a great sound.
https://www.youtube.com/watch?v=-AFGz1JmyDM
The mix is for s#!+ but his guitar cuts through. Note solo time where he plays harmonica with one hand and hammers on the guitar with the other.
So, it's courses for horses as usual. Some amps don't need "improvement."
down technical blind alleys . . .
Re: raise filtering on blackface vibrolux ?
Very good! Very good!
I build and repair tube amps. http://amps.monkeymatic.com
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hitchcaster
- Posts: 296
- Joined: Thu Jun 01, 2006 12:30 am
Re: raise filtering on blackface vibrolux ?
wow that's pretty cool! 
i just assumed they were doing what they thought sounded best for the circuit... not how much money can we save using slightly cheaper caps... good thing there were no shitty iron options back then yeah i think i'm gonna use SS plug in rec and get the first stage up.. i liked the srv direction in my super .. thanks !!
i just assumed they were doing what they thought sounded best for the circuit... not how much money can we save using slightly cheaper caps... good thing there were no shitty iron options back then yeah i think i'm gonna use SS plug in rec and get the first stage up.. i liked the srv direction in my super .. thanks !!