Just for fun: Attempt at #40 schematic...

[markmalin]

Well, there are US laws on all that stuff and anyone in the business of selling amps needs to know those. I don't sell amps and I'm no trademark lawyer, and don't know those laws, so, I won't comment and let you guys battle it out

Just to point out another way to look at it, though. Without discussing legal matters, I think it can be seen as ethically "wrong" to put one's own trademark on someone else's circuit.

I hear yah... I've often wondered about this. How much do you need to alter a circuit to be able to sell it? Of course... Marshall's first amp was a Fender Bassman. "Was", not "was like", from what I understand.

[Bob-I]

I hear yah... I've often wondered about this. How much do you need to alter a circuit to be able to sell it? Of course... Marshall's first amp was a Fender Bassman. "Was", not "was like", from what I understand.

Just to put this to bed....

You can't copyrite a circuit, only the tube. Western Electric published schematics like this to ensure that engineers could successfully a device so they could sell tubes. The Fender Bassman was taken from these circuits.

Marshall was very close to, but not exactly the Bassman. They used different iron and turns ratios. As for the resistors and caps, eve they were the same, but who cares, they were taken from the tube manuals.

[Funkalicousgroove]

First off, DUMBLE is indeed a registered federal trademark, I looked it up on the USPTO.

Secondly, I'm about to spill the beans on the 70's amp, since I have worked on one from this era, I'm sure it's about the same-

First is the PI/output:
Plate resistors are 47K/51K, Grid leak resistors are 100K, grid stoppers are 1.2k or 1.5k, output couplers are .05uf. PI cathode is 470r, 22k, 100r to ground, I believe the NFB resistor in these is 820r. the accent switch is .1uf in this circuit. the PI coupler is .001uf.

OD:
Both coupling caps are .01uf, 100K plates, 1.5K cathodes, the network off the v2b coupler is 100K(180K in some) to ground, 1M in series.

68K grid stopers on both sides.

I'll have to go back to my notes for the pre-OD network-

Clean: .1 bass, .01 mid, 100k slope, 330pf treble(mica or ceramic) coupler is .01. 68K grid stoppers(some times 56K, later amps are 22k/220k)

the amp I saw did have teh .001 across the bass pot and a 10K to ground.

[ic-racer]

First off, DUMBLE is indeed a registered federal trademark, I looked it up on the USPTO.

Secondly, I'm about to spill the beans on the 70's amp, since I have worked on one from this era, I'm sure it's about the same-

First is the PI/output:
Plate resistors are 47K/51K, Grid leak resistors are 100K, grid stoppers are 1.2k or 1.5k, output couplers are .05uf. PI cathode is 470r, 22k, 100r to ground, I believe the NFB resistor in these is 820r. the accent switch is .1uf in this circuit. the PI coupler is .001uf.

OD:
Both coupling caps are .01uf, 100K plates, 1.5K cathodes, the network off the v2b coupler is 100K(180K in some) to ground, 1M in series.

68K grid stopers on both sides.

I'll have to go back to my notes for the pre-OD network-

Clean: .1 bass, .01 mid, 100k slope, 330pf treble(mica or ceramic) coupler is .01. 68K grid stoppers(some times 56K, later amps are 22k/220k)

the amp I saw did have teh .001 across the bass pot and a 10K to ground.

Excellent, thank you!

I was able to confirm many of those values on the banded resistors in the #40 pictures. One place where the two amps may be different is the first OD coupling cap. The pictures show the first one bigger than the second one, so perhaps .02uf and .01uf on #40.

The sizes of the PI caps match your values much better than the 70's schematic.

I had been under the impression that the '70s Schematic' was "Very Accurate." However, those values you posted and the pictures of #40, produce a much different schematic.

So, at this point I am getting pretty curious to build this thing and see how it sounds .

I have indicated in the schematic the exact providence of each component value as follows:

(P) = value ascertained from pictures of #40
(G) = guess
(O) = Observed values on a similar 70s amp (amp Brandon saw)
No notation after the value = "70s schematic" value.

Updated schematic here:

[Funkalicousgroove]

My guess on the OD Caps is that they are 2 different brands, that's how they were in the one I fixed, one cap was a CDE and one was a sprague, but both were .01

[ic-racer]

My guess on the OD Caps is that they are 2 different brands, that's how they were in the one I fixed, one cap was a CDE and one was a sprague, but both were .01

Ok, good, we will go with that; .01 & .01

How about what looks like a goofy arrangement of caps on #40's' bass pot? Any thoughts there?

[Funkalicousgroove]

Not sure there, the one I worked on was from '75 and it had the standard .001/10K tail on a 500K bass pot.

I was just looking at pics of another one from that era that has the .001 across the outside lug and wiper instead of the pot.

as far as the OD couplers, I'd try both .01 and .02 and see what you like the sound of-

[heisthl]

I was just looking at pics of another one from that era that has the .001 across the outside lug and wiper instead of the pot.
-

That gives me an idea - what if you attached the .001 to the treble pot leg so that you would get a slight bleed in PAB mode - might help address the thinness that some complain about in PAB.

[ic-racer]

Not sure there, the one I worked on was from '75 and it had the standard .001/10K tail on a 500K bass pot.

I was just looking at pics of another one from that era that has the .001 across the outside lug and wiper instead of the pot.

as far as the OD couplers, I'd try both .01 and .02 and see what you like the sound of-

Schematic updated.

Any comments on the sound of the amp you saw? SN higher or lower than #40?

[Funkalicousgroove]

The one I worked on is fantastic after I took out all the hack mods, with my '35 bakelite ricky it sounds just like lindley on "runnin on empty".

There are pics of it in the files section, it was called the "Overdrive Delux" no SN#, the back is dated 6/11/75. Supposedly it was a prototype that used to belong to lindley, can't confirm that for sure, but it sure sounds sweet!

[ic-racer]

The one I worked on is fantastic after I took out all the hack mods, with my '35 bakelite ricky it sounds just like lindley on "runnin on empty".

There are pics of it in the files section, it was called the "Overdrive Delux" no SN#, the back is dated 6/11/75. Supposedly it was a prototype that used to belong to lindley, can't confirm that for sure, but it sure sounds sweet!

Ok, now I remember the post, the one with the gold faceplate I think.

Just started working on a layout. Now sure how you guys do it, but I brought the pictures up in Photoshop and tweaked the images of the boards until they were square, instead of parallelogram. Then I brought them into the drawing program and re-sized them to some reasonable dimensions and then used this for the template.

[Funkalicousgroove]

Now that this info is up watch for The Ceriatone and Two-Rock production versions in the near future

[Hotrod Ford]

Brandon,
chill

Kitty Hawk built an amp called Kitty Hawk Standard,it was pretty much exactly based on the mid late 70s era amps with this early Dumble PI this was way back in the late 70s-early 80s (I worked on a few of those early ones both the Real Mccoy and the Kittys )
btw Gregor Hilden used to record with those Kitty Standards earlier on

well so nothing new in clone land really.

fyi also there are also several versions of the 70s amps almost as many as the 80s amps, I know HAD was constatly upgrading his design
however the most common standard versions at that time was the ones that were sent to Germany they were pretty consistent , and these were the ones that were cloned by the Kitty guys btw ,
(but the other later kitty amps in the 80s had nothing incommon with the D circuits though !

also some preamp values you mentioned on "old -75" seems not be the correct original ones , it must have been modded by the guy Steve sent it to !? the values s you mentioned here are more a mixed version of the sligthly later 70s values but they can sound good too so why not
also there were no power supply caps inside the chassie exept bias cap and a od power supplycap on the board next to the OD section, the rest were in the doghouse in that amp,
also it looked kind of strictly business but still cleaner inside when I owned it looked kind of modded inside now in the pix you posted, too bad,
that amp served me for many years on many gigs and I still own the only other ODDeluxe made which is a 50w combo .

[Funkalicousgroove]

I took out all the hack mods. Did it have the fine black spraypaint all over it when you owned it?

All the caps now reside in the doghouse, all the wrong value stuff has been restored to the original. I know who did all the hack work, but I won't mention who did it

I'm not sure which values you are referring to as being unoriginal, I took out the stuff without spraypaint, and replaced it with proper stuff- the pics are "Before".

As far as the TR/Ceriatone comments, I just love that these guys are here, contribute NOTHING AT ALL, yet they hang out here and gather information.

[ic-racer]

Looks like I am getting closer to actually building this thing. Here is my first attempt at a template to make the main board. I'll just print it out and use a center punch over each eyelet hole, then drill the holes by hand.