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my 7th amp - is a dumb bell clone worth the effort

10/31/2005 8:23 PM
pete c my 7th amp - is a dumb bell clone worth the effort
Hi Guys,  
Ive successfully built 6 amps now for personal use. A champ, a P1EX from ax84, a bassman, a plexi 50w, a 6V6 plexi and a 300B stereo amp.  
I'm a huge Robben Ford fan and I spend a long time listening to him and trying to get his licks down.  
I play guitar every day unless I'm on vacation.  
My question is this.....  
for a long time Ive been considering putting together a dumb*e clone for my own use using the hand drawn layout and Humble Overdraft schematic ive seen ion the web.  
Question is - if I spend the time on this - will I be disappointed ?  
How close is it to a "real" Dumble.  
The schems i've seen dont have positive feedback - though some reports seem to regard it as the "secret ingredient".  
For those who have built their own dumb*e - was it worth it. Does it really sound like the sought after amp.  
I'd love to do it if its going to reward me.  
I consider myself a decent player not a hacker who wants a "name" amp - so this needs to be worth it - time building is time spent away from the guitar.  
I have a nice chassis with 2 spare Partidge TXs which will do very nicely for the project.  
Any thoughts for me to consider ?  
Who has built one successfully ?  
I play a PRS MCarty and Godin LGXT, BTW - the Godin gets pretty close to some of Robbens chambered body tones.  
feedback ( even positive ;) much appreciated )  
10/31/2005 8:19 PM
Chris/CMW amps

Hi Pete  
"I play guitar every day unless I'm on vacation."  
That's not enough, just kidding! :D :)  
Robben Ford tone: to my ears 90s style *umble clean-channel with or without tonestack-bypass-boost.  
Partridges are way nicer then off the shelf or used bf/sf Fender iron.....  
Regarding positive feedback: none! On some Dumbles there's some negative feedback on the 2nd stage (resistor and cap between grid and plate).  
Hope this helps,  
10/31/2005 10:21 PM
pete c
thanks - thats cool  
PS - youre in Holland ! - nice to see  
my sister lives in Den Haag.  
any other advice greatly apreciated  
10/31/2005 9:33 PM
Chris/CMW amps

Hi Pete  
The Hague is the town from The Golden Earing ("Radar Love"), Kane and a couple of other cool bands/guys. Be sure to contact me if you're visiting the Netherlands, I'm about 1 hour from Den Haag.  
Hope some fellow Ampagers can tell about their *umble experiences too.  
10/31/2005 10:23 PM
pete c
sure will do - would be cool to check out your amps.  
next trip to Netherlands sometime in 2006.  
10/31/2005 10:46 PM
Ben Shelton

Build it.  
The touch really is everything they say it is. The amp sings. Killer for lap steel, too.  
I'm partial to the late '70s incarnations myself, without the post-OD tonestack.  
I've never built one with reverb, although I do have the schematic/layout for a '70s Overdrive Reverb that I've been meaning to build.  
Play around with the feedback. The NFB loop on the second preamp stage is really what gives the amp its character, IMHO, but everything else is up to you. I stuck an adjustable power amp NFB control in mine, and it sounds equally good (but different) with the feedback turned down.  
11/1/2005 4:10 PM

I've built 3 clones and each came out a little differently. I do like the tone on each.  
I pretty much stick to the hybrid-a schematic but throw in a few tweaks from Ben's excellent hand-drawn layout as well as a reverb circuit. ( has the reverb circuit and some excellent photos.)  
Worth it? I think so, but you'll have lots of tweaking to do before you get that Ford tone.  
Here's a short clip of my latest build using a SF Bassman chassis and trannys:  
First 45 seconds clean, second 45 seconds with some OD.  
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