The HRM Bluesmaster and the serial #102 "Ojai" Robben Ford amp are 2 completely different sounding amps. Both sound great in there own right although.

 The Ford amp has a Skyliner clean tonestack with NON-HRM OD it has more "chime'y" clean tones, and a much more focused OD w/ an almost horn like sound. This voicing has a Ratio control to balance the clean and Overdrive.It is also a very bright amp because of the large Master Volume Bright cap. The brightness is tamed with high pF (aka capacitance) RG-400 cables and a Dumbleator, also giving the amp an overall smoothing effect and increasing harmonic bloom and adding compression. A very "fast" response and a great sounding amp that all your tonal nuances will come out (good or bad LOL).

 The Bluesmaster has a Bluesmaster (Marshall/tweed Fender) style clean tonestack with HRM "bluesmaster OD".  The cleans are very girthy and has more Bass content that other voicing's. The Overdrive is also very fat sounding giving a broad range of Overdrive tones. The Bluesmaster also has a Bluesmaster Phase inverter (ala Marshall) and has less "clean headroom" then all the other voicing's. In addition it has separate Master volume controls for the clean and Overdrive. This amp also sounds better with a Dumbleator (but no need for high pF cables).

So, and sorry if I don't understand completely, is the purpose of RG-400 cable to smooth out the high end by attenuating (length/resistance) OR preserve as much high end as possible (high quality cable). Or maybe both, I can imagine certain harsher frequencies being tamed, but others untouched?

Due to the postion of the circuit whatever cable you use will always end in a high freq. loss. The RG400 is attenuating less compared to a normal cable. But still there is a noticable loss of high freq.
So yes it smooths out , but not too much compared to a regular cable.

Nice sounds pethenis! Very nice playing too ( sloppy my butt - LOL )! I enjoy your ideas - "Someday After Awhile"?

Yes, this seems to be a problem with myself also. I guess it's pretty common amongst perfectionists. What's really crazy is when you realize you're actually in a sense insulting the person doing the complimenting. It's basically questioning their judgement.

Here's a write up from erwin I believe on another post on different OTS models that discusses the different tonestacks as well


Non Hrm classiq EQ is the oldest style of dumble amp. A bit more rooted in the
raw fenderish tone. This is the amp that made his reputation. This
would be like early Lindley, Browne, Lowell George, the first
incarnation of his amps.
It can sustain like a mofo! It is a singing OD for sure.
Not much compression, very touch sensitive and dynamic....

Second the Non-HRM Skyliner EQ  low plate is a variation of the above. Dumble modded
several of his older amps with a new tone stack he was developing,
know as the skyline eq because it's output viewed on a scope resembled
a city skyline.
It is a little less Fender but still a somewhat lower gain affair. It
has the same gain as the vintage amp but the new EQ is more "signature dumble" and a little less Fender. Improved cleans from th Vintage model.
It still sustains like a mofo, has a bit better string to string definition and is a little more refined in the tone shaping.

Non-HRM Skyliner EQ  high plate is where he went next, same as above but now the
gain staging is not classic fender. It has more headroom, definition, and punch, more lively and responsive cleans, smoother OD, and a small bit of compression, very touch sensitive, lots of sweet singing tones.

HRM Skyliner EQ   HRM stands for
"Hot Rubber Monkey". This is a second tone stack just for the OD
channel. It is more or less a Marshall style tone stack this allows tone
shaping of the OD independent of the cleans.
A real Dumble of this ilk would be called a Skyline HRM. Smooth as silk, goes from clean to mean like no ones biz. Transition
between is amazing. You can pick clean, a bit dirty, grinding, soaring, all
with your hand and all smoothly with definition. No rasp or buzz. Very refined. Gorgeous smooth tones. A little more compression that the above amps but not in a bad way. Very natural. The dynamic response is second to none. This amps feels like it breathes with you after awhile.
Smooth singing overdrive, completely dynamic, never any rasp or buzz, no IM distortion or other uglies.

Blues Master. Think raw early Fender/Marshall
tone on steroids. The tone stack is decidedly bassman territory,
however because of Dumbles many other difference it is far better IMO.
The cleans here are the best cleans I think I have ever heard, dumble
or otherwise. The cleans will sing and sustain!!! The OD is much less smooth and much less compressed than the above amps. It has some early Marshall vibe to it. Boosted cleans with this amp are to die for. The OD is a bit more raw and edgy then some of the other offerings but with boosted cleans you get the smooth side of things and with the OD you have a less polite and refined tone.
Somewhat like the first Dumbles, though different. Lots of punch, sustain and singing but not as smooth as some of the other offerings. This one can be thick and dense too. Not dark and crappy, just "meaty"...
Open clean cleans to mean and a little rude.
Big fat sick blues machine. Lots of character or soul. This amp will try and steal your girl.Like a tuxedo on a cowboy?.... It can play nice but it can still stomp in the dirt.
last is the same as above with the HRM OD tone stack which gives a little more tone shaping and refining in the OD section.





hope this helps!

Gregg

Great to hear all you ampheads responses and videos.
Sasquatch...I had a 50 HRM OTS with a Hermida 1x12 closed back frontported cab witha EVM 12L and a TOm Anderson strat(single coils). Sounded great.I imagine humbuckers sound great as well. (Carlton/Ford)Seems they use partial open oval back cabs. I also had a Fender Vibro-King.Awesome amp,but sold it. SO now I only have the 1x12 cab...no amp..no guitar..LOL.  (Out of work architect) Am thinking Im gonna get a 50 watt OTS Ford or a 50 watt HRM Bluesmaster. Any model OTS is gonna put a smile on my face though.THe HRM clean channel would be great for a traditional jazz player...(or put a Tubescreamer in front of it and Im sure it would be effective.)Like most of you guys ...Ive had fenders,marshalls and boogies and they are nice but there is something about a d-style amp that kicks it up anotch..and the ceriatones are soooo much amp for the money.Got to get another one.