3rd Gen Dumble or Two Rock JM Sig?

[kkillebrew]

Hi There,

I've been lurking here lately seeking some inspiration for a new build. Been building amps for 40 years but never focused on Dumble. Currently playing through a Fender (Rivera Era) Twin II which is too heavy and too loud. Not crazy about the OD in the twin but the clean sound is killer.

My last build, a Tremolux/Deluxe variation with reverb sounds killer but is not loud enough, and to some extent not cabinet tough enough to gig reliably with.

Sooo... I have stripped son's barely used Fender Hot Rod Deluxe, certainly one of the worst sounding all tube Fender amps ever made, and am going to build the medium power amp I need in this chassis. The build quality, fit and finish, and toughness of the Fender HRD cabinet top notch and I can use the chassis as is. Going to start out with the stock power, output, and choke transformers, as well as the 5581's which should yield around 40 watts. Not sure what the iron will sound like with a good point to point wired Dumble style pre and driver circuit but I'm going to give it a chance.

My indecision lies in whether to build the 3rd gen Dumble OD or the Two Rock clean only pre with reverb... leaning toward the Dumble because I have a great Eventide delay and I'm not really satisfied with any stompbox OD I've tried in comparison to the Dumble 3rd gen OD I'e heard.

Any thoughts on the Fender HRD iron and cab and how it may or may not lend itself to this project? Really looking for sound, tone, and circuit comments. Thanks!

Kevin K
Austin

[martin manning]

I'm not aware of any such conversion on the forum to-date, but it seems straight-forward. I'd go for the D circuit if you are after a nice tube OD, maybe squeeze a D'lator buffered loop in if you can find the room. No reason not to try the transformers you have and see how they work out. Who knows? You might start a trend.

[amplifiednation]

Fuchs does an HRD conversion and I know the results are spectacular

[kkillebrew]

I'm not aware of any such conversion on the forum to-date, but it seems straight-forward. I'd go for the D circuit if you are after a nice tube OD, maybe squeeze a D'lator buffered loop in if you can find the room. No reason not to try the transformers you have and see how they work out. Who knows? You might start a trend.

Good suggestion, I think the Dumblator is the way to go since I can loop my Eventide through it's line in/out and won't need reverb built into the amp. There are three triodes in the HRD but room on the chassis to punch one more, and with 3.2A filament windings there is current enough to support it as well.

KK

[David Root]

Why clone half of a clone? Go with the 3rd gen, my $0.02, more versatile. The HRD iron should do but BF Bassman iron I would think would be bigger/fuller sounding.

[M Fowler]

https://tubeamparchive.com/viewtopic.ph ... hlight=hrd

https://tubeamparchive.com/viewtopic.ph ... highlight=

[kkillebrew]

Why clone half of a clone? Go with the 3rd gen, my $0.02, more versatile. The HRD iron should do but BF Bassman iron I would think would be bigger/fuller sounding.

Hi David - Not exactly sure what you mean by cloning half of a clone, but I am going with the 3rd gen OD.

[kkillebrew]

https://tubeamparchive.com/viewtopic.ph ... hlight=hrd

https://tubeamparchive.com/viewtopic.ph ... highlight=

Nice threads. Thanks. I'm doing the total strip down thing with point to point.

[David Root]

kk, you mentioned a "clean pre only" which is half an ODS.

[kkillebrew]

kk, you mentioned a "clean pre only" which is half an ODS.

Okay got it. What I mean is either an ODS (both halves) OR a clean pre with reverb.

I don't have room for both and I keep going back and forth.

[kkillebrew]

Just got a new 68 Vibrolux Reverb reissue and have been using that, so without the urgency of needing a mid sized amp this build is going very slow. But I have finally decided on the configuration.

I'm using the existing Fender Hot Rod Deluxe iron good for about 35 watts and I'm adding three more triodes to facilitate tube reverb and tremolo. YES the power tranny handles the extra .9 amp filament draw just fine and maintains a healthy 6.8v with no overheating.

It's going to be an ODS 3rd gen as posted by Tony Albany, but with a two triode fender style reverb that can be switched in or out of the circuit completely to preserve the original Dumble sound. Reverb will be post OD. The trick, I believe, will be whether or not I can get the reverb recovery and buffering accomplished with a single triode. If not I can steal one side form the tremolo.

Not sure about what type of trem to implement... My fav is bias trem but the 6l6's (Sovtec 5881's in this case) may or may be a good match in this case.

In a smaller amp I've recently installed a modified version of the Trill circuit that shunts the gate of an FET buffer and it sounds very nice.

Dumble used the cathode of the first triode I've seen, and then there is the fender roach method.

Comments?

[wjdunham]

Sooo... I have stripped son's barely used Fender Hot Rod Deluxe, certainly one of the worst sounding all tube Fender amps ever made, and am going to build the medium power amp I need in this chassis. The build quality, fit and finish, and toughness of the Fender HRD cabinet top notch and I can use the chassis as is. Going to start out with the stock power, output, and choke transformers, as well as the 5581's which should yield around 40 watts. Not sure what the iron will sound like with a good point to point wired Dumble style pre and driver circuit but I'm going to give it a chance.

Certainly not one of their best efforts... I'd spend the extra $60 and upgrade the output transformer to a good USA made Bassman unit, especially if you are going to be pushing the amp, which I suspect you will be if your previous build was not "loud enough".

Bill

www.sebagosound.com

[kkillebrew]

Certainly not one of their best efforts... I'd spend the extra $60 and upgrade the output transformer to a good USA made Bassman unit, especially if you are going to be pushing the amp, which I suspect you will be if your previous build was not "loud enough".

Bill

www.sebagosound.com

Where can I get one for $60? It will be an easy upgrade if I want to do it later. If I can get 35 watts I'll be happy so we will see. I'm actually more concerned about the output transformer quality. Not sure what made the HRD sound so horrible but I'm hoping it was not in the output iron.