New Used Amp Day, a Dumblish Thing

[kbp810]

Always been intrigued by Dumble clones, since I have neither the disposable income level nor sense of extreme financial irresponsibility it takes to buy the real thing. I've had some come and go in the past, but it's been quite a long while (probably 10 years or more) since I've had one in the stable. 

So when I happened to spot this one in a reverb ad while browsing another un-related forum, it grabbed my attention, and money was ultimately spent. I think I've heard of this builder before? Think his name has come up in this forum a few times in the past with mostly positive feedback. 

This is an overddrive special "HRM" variation. There's been some debate over what HRM actually stood for, but I believe someone had caught Alexander stating it stood for "Hot Rubber Monkey". Essentially, it's an ODS, but with an additional internal tweakable tone stack that comes after the overdrive stage for some serious fine tuning. This one also had one of the trim pots swapped with an externally mounted pot so that the OD trim level could be easily adjusted on the fly without opening the chassis up. 

It had an interesting tolex choice; black sparkle with a strip of silver sparkle on top... though this amps seen plenty of use over the years, and it shows. Some of the tolex is starting to lift. This is certainly a heavy beast; I caught some side eye from the delivery guy carrying it, even though I tried to meet him halfway to help save his back. 

Aside from a little scratchiness in the pots, it sounds magnificent, as any good ODS should. Especially on the OD channel. The speaker was sounding a little fizzy... swapped it to a Fane A60, and initial impression is that this was a wise decision. I may also eventually re-cover it... sometime in the near future I'll take it apart and get some gut shots. I don't have it in me at the moment after lugging to the house, unboxing, tinkering, and speaker swapping. 

 

 

 

 

[Gitfiddler]

Sweet rig.  It was nice of the former owner to put your initials on the faceplate for you.  🙂

Looking forward to your full review and obligatory gut shots.

[kbp810]

2 hours ago, Gitfiddler said:

Sweet rig.  It was nice of the former owner to put your initials on the faceplate for you.  🙂

Looking forward to your full review and obligatory gut shots.

Yeah, I thought that was nice of him too! 

[Steiner]

Ah, for the good, old days...
Once upon a time there was a young, fledgling amp builder - pseudo local - that would drop by with his new creations.  It was the best of times; Voxs, Marshalls, Fenders all well above the commercially available stock...  One day he brought an ODS.  It was that day I remember the clouds parting and the sun shone bright on the sound that beast brought forth enveloped all the nearby nature.
If memory serves, that luscious behemoth had big, blue trannies.  Could this be the one?

Congrats!

[yoslate]

Would love to take that one out for a test drive!  Heavyweight iron!

[TalismanRich]

It's pretty cool that the builder did a nice combo setup.   He must be a real pro at building stuff like this!

I've always been intrigued by the D style amps.   I've never played one, and really don't know if I could justify spending the money on something just to play in the basement.  

[bolero]

I had an Ampeg SVT for a while, that sounded glorious with guitar. I heard Dumble's steel string singer is somewhat based on an SVT? If so, I'm not surprised.

I've never tried a Dumble or a clone though.

ODS is blackface Fender, with tweaks?

[DetroitBlues]

Nice to see her back in a good home.  If only I wasn’t so foolish not to let go of not one but three KBP amps…

[212Mavguy]

 

Hard to find a speaker that makes D- tones more sweetly musical in rendering harmonics than that particular Fane.  I love those Alnico Fanes, have a 100watt AXA 12.  

On my C-tone HRM head I swapped out the resistor from the HRM mid pot to ground to a much higher value, around 30k IIRC up from stock 10K so that the HRM pots were less effective in tone changes and more signal gets passed on the the P. I. instead of being dumped to ground.  Running RFT el34's in mine.  Has the lift negative feedback switch on V1 like yours.  Do try a strong vintage Tung Sol 5751 long plate for V1... in that circuit it's worth the looking for.

Major wow factor you have there.   KUDOS!

TR, if you can afford more than three Heritage guitars you can afford to pick up a used Ceriatone HRM or ODS, they're not unobtanium anymore.  They don't break, have great parts inside they are affordable for what they can do, hold value well, have a monstrously huge tone palette able to handle about anything with pickups, and they are among the most true to original circuits and parts selection other than their custom iron which is beyond good.    If a power tube screen blows the amp is repair friendly.  Keep a watch on fleabay or reverb.   Marsh Overlord is a great, affordable 80's D-clone.   I stuck a Classic Tone 50w Marshall clone OT in mine...WOW.   RedPlate makes tweaked D-clones that can be found used, their builds are insanely good, somewhat expensive.  

The original, only 6 or 7 Steel string singers ever built used a driver tube for each half of the phase inverter to push 3 pairs of 6550's grids.  It sustains unusually well... clean tones.  The FET channel in the preamp is the secret SRV tone sauce along with the filter tone knobs later on in the circuit.  The SSS from Ceriatone lacks those driver tubes in the PI section, and they run a quad of 6l6's for 100 watts.  Mine, even at 100 instead of 300 watts needs to run at half power setting hard on the tubes and darker sounding or use a C-lator in the loop, the real one likely needed a Dumbulator in the loop to control the output to sensible, usable SPL levels on most stages.  It's loud, loud, loud without a 'lator in the loop, even with the nice pots that the builder used... still...nope, IMO master volume too sensitive when gain and FET distortion and the unique to SSS tone filters are switched on.  I would not use an attenuator with one, the C-lator is the way.  Does get the SRV tones and sustains cleans well, obviously a pedal platform.

 

[tsp17]

Life comes full circle!