1978 Dumbleland Special #009 Chassis & Photos

[rccolgan]

Hi TAG Friends!

Since a plethora of Dumbleland #0011 information was published here https://ampgarage.com/forum/viewtopic.p ... 01#p485501 I thought i'd help with some information and photos I have on #009 as well as the chassis files I've been working on that will cover both #009 and #0011. My intention was to start a whole new project like I did with SSS #002 however my work/life balance is preventing me from focusing on that effort. I hope that releasing this info I have will ignite the collective TAG community to pitch in and push the project forward so we can make a few!

Dumbleland Chassis Fabrication Files: https://github.com/colganr/DLAND-009
1978 Dumbleland Special #009 Photo Album: https://photos.app.goo.gl/ww1EfGgSSGbgSwRF6

I wanted to call my clone of the Dumbleland #009 to be called the "Deadland Special" since John Mayer used the real #009 with Dead & Company. My request is whoever picks up the chassis fabrication and artwork to consider labeling the amp as the Deadland Special or at least making that space blank so we can add our own vinyl transfers.

If the project seems to take off, I can hopefully offer to design & fabricate the PCBs for the community here (as time allows). I just need help with everyone's input what the schematic and layout/routes are for the components.

Big thanks to the anonymous source for the photos of #009 and HaenZ for the detailed pics of #0011!

Forever Grateful,
-Ryan

[martin manning]

I think the detailed 011 schematic is it. The biggest question I had was whether HAD was really running the 6550 load line that far below the knee, and the 011 info has all but confirmed he was. Still don't have a positive read on the OT Za-a. One might consider reworking the filters for 7-position switches, and maybe adding a mini-toggle for the other functions.

I wanted to call my clone of the Dumbleland #009 to be called the "Deadland Special" since John Mayer used the real #009 with Dead & Company.

The Dead were known to cover Chuck Berry: https://www.youtube.com/watch?v=Ip48SfRx4ho and Dead & Co. followed suit. In light of that maybe "Promised Land Special" would be a good name? And then of course there is the double entendre...

[Max]

... Since a plethora of Dumbleland #0011 information was published here https://ampgarage.com/forum/viewtopic.p ... 01#p485501 I thought i'd help with some information and photos I have on #009 as well as the chassis files I've been working on that will cover both #009 and #0011. ...

Some remarks:

Revised schematic of DL#009 shows a "classic" tonestack, no CF driven PI, and UL-connections:

REVISED 009 SCHEMATIC.jpg

Schematic (and photos) of DL#011 show a "pre-classic" tonestack (https://ampgarage.com/forum/download/fi ... &mode=view), a CF driven PI, and no UL-connections: https://captain-guitar-lounge.com/wp-co ... _011-2.pdf

The photos of DL #009 linked above by rccolgan in his opening post show a H.D. signature from 1978, treble and mid pot date codes from 1997, and an SBE (founded 1986) mid capacitor.

This photo linked above by rccolgan shows DL#008 with a different chassis (two rows of tubes):

dland #008.jpg

[Max]

Here are the photos of DL#009 linked by rccolgan in his opening post and that I referred to in my previous post (1978 signature, 1997 treble and mid pots, SBE mid cap):

[dbharris]

Ryan, thanks so much for sharing this info and the pics are awesome!

Max, keen eye as always. Do you have any thoughts on whether these newer parts were due to normal service replacements or perhaps an upgrade/modification?

Thanks,

Dan

[Max]

I think the detailed 011 schematic is it. ...

What exactly do you mean by that? I ask because the circuits shown in the following two photos of DL#009 and DL#011 look quite different to me:

DL#009

DL#009 V1 V2 board.jpeg

DL#011

DL#011 V1V2 board.jpg

Could you please briefly explain the differences and similarities between these two circuits?

[Max]

... Max, keen eye as always. Do you have any thoughts on whether these newer parts were due to normal service replacements or perhaps an upgrade/modification? ...

Thank you for the flowers . I consider it highly unlikely that a defect in the previous "pre-classic" treble and middle capacitors was the reason for replacing them by the newer "classic" components. I am therefore inclined to believe that the tonestack of DL#009 was modified from the "pre-classic" version to the "classic" version sometime after 1997 - perhaps at the same time the previous round knobs (see the picture below linked here by rccolgan) were replaced by the current black pointer knobs.

[martin manning]

I think the detailed 011 schematic is it. ...

What exactly do you mean by that? I ask because the circuits shown in the following two photos of DL#009 and DL#011 look quite different to me:

Could you please briefly explain the differences and similarities between these two circuits?

Well, I don't really know. That would require tracing 009 out to the level of detail that is available in the 011 schematic. Maybe Ryan will get there, but with only phots to work from it is not an easy task. I would probably use the 011 schematic and try to match the 009 photos to it. Since these two SN's are only 2 apart I would expect that they are quite similar electrically, even if the board layouts are quite different. For someone wanting to build a Dumbleland, the shortest path would be to use the 011 information. That is what I am saying above. Knowing exactly what 009's circuit is would be of some value, as it could show some interesting evolution or perhaps some significant change.

[dbharris]

... Max, keen eye as always. Do you have any thoughts on whether these newer parts were due to normal service replacements or perhaps an upgrade/modification? ...

Thank you for the flowers . I consider it highly unlikely that a defect in the previous "pre-classic" treble and middle capacitors was the reason for replacing them by the newer "classic" components. I am therefore inclined to believe that the tonestack of DL#009 was modified from the "pre-classic" version to the "classic" version sometime after 1997 - perhaps at the same time the previous round knobs (see the picture below linked here by rccolgan) were replaced by the current black pointer knobs.

Thanks, this seems obvious that those parts would not all fail together, but sometimes I think we can all assume too much about everything Dumble. For instance, I had assumed that by 1997 Dumble was using the skyline and bluesmaster tonestacks and would not have upgraded to a classic tonestack. Of course I am sure he did what he believed was in furtherance of this client's desired sound.

Thanks for your thoughts.

-Dan

[Max]

... Since these two SN's are only 2 apart I would expect that they are quite similar electrically, even if the board layouts are quite different. ,,,

Thanks for your comments. May it be possible that some components visible on this circuit board (DL#009)

DL#009 V1 V2 board.jpeg

belong to some feedback connection(s) like those shown in this schematic for SSS#002,

SSS#002.png

but which are not discernible in the photos and schematic for DL#011 https://captain-guitar-lounge.com/2026/ ... 979-dumble ?

... but sometimes I think we can all assume too much about everything Dumble. For instance, I had assumed that by 1997 Dumble was using the skyline and bluesmaster tonestacks and would not have upgraded to a classic tonestack.

You're probably right about that. Another example: As I understand it, the designation "classic" is based merely on the wrong assumption that this "classic" tonestack is the tonestack design typical of all the early ODS amplifiers from around 1973 until around 1979.

[martin manning]

May it be possible that some components visible on this circuit board (DL#009) belong to some feedback connection(s) like those shown in this schematic for SSS#002, but which are not discernible in the photos and schematic for DL#011 https://captain-guitar-lounge.com/2026/ ... 979-dumble ?

It certainly looks like there is some un-bypassed portion of the cathode resistances (the 100R), and that is a form of negative feedback, but I do not see any connection to the top of the 100 ohm resistors (junction of the 100R and the parallel Rk-Ck) as in 002. Could be under the board, or maybe the NFB was abandoned and that is why 011 doesn't have the 100R. BTW, I would not refer to that SSS 002 schematic. There is a much better one that came out Ryan’s effort to correct errors in the "Japanese" schematic.

[martin manning]

...

[rccolgan]

May it be possible that some components visible on this circuit board (DL#009) belong to some feedback connection(s) like those shown in this schematic for SSS#002, but which are not discernible in the photos and schematic for DL#011 https://captain-guitar-lounge.com/2026/ ... 979-dumble ?

It certainly looks like there is some un-bypassed portion of the cathode resistances (the 100R), and that is a form of negative feedback, but I do not see any connection to the top of the 100 ohm resistors (junction of the 100R and the parallel Rk-Ck) as in 002. Could be under the board, or maybe the NFB was abandoned and that is why 011 doesn't have the 100R. BTW, I would not refer to that SSS 002 schematic. There is a much better one that came out Ryan’s effort to correct errors in the "Japanese" schematic.

I didn't do a trace to verify but when speaking to one source close to the amp about #009 is "pretty much" SSS #002 preamp without reverb so I think this is in the right direction. That was well before I got pics and was doing some ground work when designing the chassis.

[martin manning]

I didn't do a trace to verify but when speaking to one source close to the amp about #009 is "pretty much" SSS #002 preamp without reverb so I think this is in the right direction.

Here is a comparison of SSS 002 and DL 011 preamps. I'd say that is a fair description, except the DL is voiced for bass. I think the 009 had the feedback loops initially, and later they were removed. Perhaps the 011 was built without them from the start, and the board layout was revised to reflect that change.

[Max]

... I think the 009 had the feedback loops initially, and later they were removed. ...

Why do you think so? I ask because, in my opinion, the four parts marked with blue arrows in the following photo of DL#009 could quite plausibly correspond to two connections of the "LNFB" and "LNFB2" type. Or am I mistaken?