Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dude on March 30, 2022, 05:20:35 pm

Title: Boost switch on AB763
Post by: dude on March 30, 2022, 05:20:35 pm
One of my favorite amps is Sluckey’s Deluxe Lite, single channel AB 763.  I added a pre PI master, took the 220k out and replaced R14 with a 500kA pot. Nice overdrive and very loud, l like it. To get a cleaner sound l was thinking of adding the 220k to the wiper in series to ground with a switch between. I’d call it a boost, switching that 220k in for a cleaner sound and out for a more gain, also still having the master. Make sense?
Title: Re: Boost switch on AB763
Post by: sluckey on March 30, 2022, 06:09:29 pm
Easy to try. Let us know what you think.
Title: Re: Boost switch on AB763
Post by: dude on April 02, 2022, 06:09:56 pm
Putting that 220k in the amp today, would it make a difference if before the master or after..? I wouldn't ‘t think so..?
Title: Re: Boost switch on AB763
Post by: PRR on April 03, 2022, 11:58:28 am
> would it make a difference if

Get the iron hot. Tin the resistor leads. Refresh solder on pot leads. Try it various places. Takes a few minutes. Why strain a brain? 'Specially since thinking won't tell you how it "sounds" like trying will.
Title: Re: Boost switch on AB763
Post by: dude on April 03, 2022, 03:05:54 pm
Well, getting the iron hot and screwing around, l mean with the amp  :icon_biggrin: , I found switching that 220k is a total useless mod. After all, yes l have a master replacing the 470k, so totally useless as it’s the same as turning the master volume down.
The old Vintage club 20 chassis l used had a boost hole, so l thought l use it. Well, through trial and error, l finally found a place for that boost hole, a raw “pot”.
Here’s what I did to Sluckey’s Deluxe AB763 single channel Lite: Rather than a raw switch l put a mini 250k pot in that boost hole, wired it just like a switch, now l have a variable raw pot, l can dial in the gain from 0 to 10. Also, found out that the the PI was slammed too hard, I added the 220k in series to the master volume, did the trick.
I’m totally satisfied, had Sluckey just said it was a waste of time, l would have never touched the amp. I’m glad he said what he did, l learn from mistakes.
I added a presence pot too, works great.
I recommend anyone who likes a Deluxe Reverb, but doesn’t need reverb built this Deluxe Lite, put the pre-PI master, 500k pot and leave the 220k in the circuit.
Cheers