Funkalicousgroove wrote:Ummm, HRM refers to "Hot Rubber Monkey" whch is ONLY the Post OD tonestack Overdrive section. If your Clean side is too Bassy Perhaps you've wired something incorrectly, it is my experience in the amps I've built that the amps with no LNFB have a much chimier and open clean sound. the Correct slope for any skyline EQ is 150K. You can always try different Plate values, the lower the value the Brighter the sound.
For what it's worth, to me the HRM amps w/Skyline EQ have a very good sounding clean channel. However, they are a bit bass heavy to my ears, but not in an unbalanced way. These amps have a thump to it that is rather impressive. "Better" than that would be the cleans on a 100K plate load amp with Skyline EQ and with the negative feedback around V1B; this would be #124, so, a non HRM. The negative feedback thing contains some of the treble and some of the punch, and the 100K plate load resistors provide additional chime... maybe too much so in OD, but that can be addressed simply with a treble gat for the overdrive channel only.
Best of all Dumble cleans, IMNSHO, are the cleans on the Blues Master. As you probably all know by now, that is a blackface style tone stack with a lower value slope resistor, bass and mid caps being .022uF (the Fender mod recommended by Ken Fisher), and the trademark Dumble 390pF (or equivalent, as it were) treble cap.
Funkalicousgroove wrote:Ummm, HRM refers to "Hot Rubber Monkey" whch is ONLY the Post OD tonestack Overdrive section.
Isn't it true though (and I'm asking this becuase you are the guy to ask) that the LNFB was generally present in non-HRMs and not present in HRMs? I haven't experimented to see how much this does or doesn't effect the cleans, but am just curious.
As a basic general statement You are correct that most of the amps with HRM Overdrive do not have the feedback on v1, but there are a few out there that do have the feedback and the HRM overdrive.
Sorry, folks, but I don't know any better... Please let me admit that a little knowledge can be a dangerous and expensive thing to have... I guess I got tripped up by the post about "Correct"ness... What is an incorrect amp configuration?
Background noise:
I am about to launch on my first D-type amp build. ( A D'Lite BlueMonkey 44 reverb kit... ) I've little ( no ) experience with "real" Dumbles of any stripe... Questions come up as I'm getting ready to build a wonder amp.
Skyline is a specific tone stack.
Bluesmaster is the (mostly?) PI configuration.
HRM is the second tone stack, with no local feedback on V1b...
High and low plates are in here somewhere...
Negative feedback resistor/cap values as well...
Some amps could be equipped with any combination of these, but most are distinct?
Is there a Skyline/Bluesmaster/HRM/Local feedback/( choke / RF mod )?
I kind of get confused.
What will happen if I decide to wire the V1b network and HRM on the same amp? Will it barely work, sound great, or boil off the ozone layer?
What if I use Sozo mustard caps instead of 6PS OD caps? Or only Sozos in the HRM and 6PS the clean stack? Vice versa?
If I install the RF mod, switchable or not, as well as the choke, have I created some abomination?
How about adding the Trainwreck MOV ty the IEC and 1N4007 strings from power tube plates to ground with all the other combinations?
If I do all of them to one amp do I have to turn in my soldering station?
If somebody has already done this and it sucks, please let me know, and I won't waste time trying it...
Bob Simpson
Last edited by Bob Simpson on Tue Apr 14, 2009 6:09 pm, edited 1 time in total.
Take it one step at a time...
You can see these amps as built in modules...you can experiment with every configuration you want, even if there are some milestones that are intended to be respected (lead dress, plates configurations, shielded cable of a certain capacitance and so on)
You can start with the super reliable ODS101 HRM...is the perfect union of classic heritage sounds into a "modern" shape...you can play blues with it, but you can also play hard rock if you want.
It has the Skyline EQ, and the post OD tonestack, the Hot Rubber Monkey (HRM), active when you stomp over the PAB button...
For someone just getting his feet wet with this I think it's best to stick to the tried and true so you'll have an idea how it's "supposed" to sound and then go ahead and tweak from there. If you start out with a mismatch of stuff you may or may not get a great sounding amp but you'll never know how good it could have sounded. Just a suggestion.
As many people who have been on this forum for some time can tell you this topic has been covered more than once.. The balancing act between the clean channel and OD is just that and as I've come to love and hate the Dumble design.... This is in my opinion the weakest part of the topology..(From a design stand point)...From what I understand and could be wrong is the higher plates/ cathodes..180/220/150 increases the voltage output of the preamp tubes..Putting it more in the middle of the Trans. curve of the tube.. Preventing the tube from clipping as easily it also to my ears tightens things and adds to the bass response.. A tight thick clean channel translates to a smoother thicker OD..
The voltages are also somewhat of a balancing act as The higher Volt say in the 200-210v range helps to brighten things up giving the amp more life on the top end but the higher voltages on the OD can lose some of the organic feel and can with the wrong tube start to get a bit harsh when you lean into it.... Since you have better control over the OD channel of the HRM the issues can be somewhat masked.. as I think Gill mentioned in one of his threads concerning the lower plates is you notice the somewhat grainer tone sitting in the living room but at a gig with the amp run up a bit it sits well in the mix..Which I agree with..It also has to do with choosing the right guitar/speakers and finding the magic pre tube that works in the grand scheme of things..In most cases picking the tube by the brand won't in my experience always get you there.. I doubt this helps you but it's what goes on in the back of my mind when begin a D-Style build....
Tony VVT
Last edited by talbany on Tue Apr 14, 2009 7:48 pm, edited 1 time in total.
