Anybody tried the Dumble mods for blackface fenders?

[Mark C]

You may have seen them on schematic heaven. A mod for the normal channel. Obviously it wouldn't give you the exact Dumble tone, but does anyone think this might be a worthwhile mod for a Fender type amp?

http://www.schematicheaven.com/dumbleamps/mod3.pdf

[Darkbluemurder]

Basically it is replacing the BF clean channel with a Dumble clean channel. It works but the exact result depends on the amp you are converting. Soundwise you will get more mids and a warmer tone. You still can retain some of the Fender mid scoop by keeping the mid control below 2 on the control.

Worthwile on a Fender normal channel? You are probably not using the normal channel anyway so why not?

Have fun
Stephan

[Icetech]

If you have a old fender, the transformers are a great starting point.... gut it and create a full amp... at least thats my opinion:) i spent years just modding my fenders and it always just seems like a modded amp, if that makes sense...

[pureoldsound]

What year is your blackface? Those might worth some $$$, better to get a silverface and gut it...Just IMHO...

[Luthierwnc]

Ditto. Don't mod a Blackface anything unless someone has already hacked it around. Amps from that era are worth more than the sum of their parts. You want a donor that is worth less than the sum of the parts.

FWIW, the bottom seems to have dropped out of the donor amp market. Big monoblocks from the 1950's and '60's can be had for a hundred bucks again on eBay.

Skip

[BobW]

If you are going to gut a blackface anyway, the only leftovers will be the chassis and transformers. so you may as well just build one from scratch. There are a lot of great designs to leverage on this forum. have fun

[Mark C]

Thanks guys,
It's not a real blackface - I wouldn't gut one of those. I'm building a clone of a blackface and am toying with ideas for the normal channel, since they don't do much in stock form.

[Pete]

my $0.02, if it is a clone of a blackface without the replica appearance, leave out the Normal channel. (then the D. clone would be another amp)

Thanks guys,
It's not a real blackface - I wouldn't gut one of those. I'm building a clone of a blackface and am toying with ideas for the normal channel, since they don't do much in stock form.

[jaysg]

Mark, my thought is that the Dumble ts is more generic than the BF. What I mean is, it will sound like an electric guitar, not an electric guitar running into a BF amp. I think that alone is worth the effort. Assuming BF cosmetics or style chassis, there are pull switches at hoffman for mid-boost and whatever else you want to try. If you have the room, putting that and the PAB on relays & footswitch could be rewarding.

[stratcat62]

I'm considering doing this mod to my blackfaced SF Twin Reverb. Like many people, I want that Dumble tone, but unlike many, I don't want the overdrive channel. I bought the TR because I wanted to get something close to a SSS because I couldn't find a schematic. Would putting a mod like this on the Vibrato channel instead give it a more Dumble-authentic tone because of the extra gain stage in the reverb section? Thanks.

[Bob-I]

I'm considering doing this mod to my blackfaced SF Twin Reverb. Like many people, I want that Dumble tone, but unlike many, I don't want the overdrive channel. I bought the TR because I wanted to get something close to a SSS because I couldn't find a schematic. Would putting a mod like this on the Vibrato channel instead give it a more Dumble-authentic tone because of the extra gain stage in the reverb section? Thanks.

Many folks like the Dumble clean, like you said SRV used the SSS which has a cathode follower for each side of the power section.

You might look into the Ampeg SVT schematic for how this is done. It takes a single dual triode so you have the tube complement in the BF Fender. You could either remove the trem or switch to a single tube reverb and use that tube for the CF stages.

The Dumble SSS was clean all the way to full power so the extra gain stage isn't needed. The CF for lower impedance loading might be the way to go.