Dumbleland Special 150w ser#009 Schematic

[talbany]

I was told ("for bass") by someone who at the time I thought, for a variety of reasons, that he knew (as opposed to: that he assumed).

Great care to share those reasons. I am sure they must have been pretty convincing for you to be able to call #009 a bass amp on the garage or was it someone who mistakenly have thought it was a bass amp and just took his word for it? (some guy told me it was a bass amp )

But as far as I know, Merle Haggard isn't a bass player.

Yeah i know which surprised me when you called it a bass amp

Apart from that, I - as well as some other guitarists who once (about 25 years ago) had the opportunity to compare the tone and feel of DLS#009 with the tone and feel of DLS#008 - also had the subjective personal impression that #008 was more likely built for a guitarist and #009 more likely for a bass player.

So somebody thought it was a Bass amp by the way it felt.

And - as you already quoted:I've never perceived that much of an important difference in a practical sense between those for bass and those for guitar anyway

I would think as a Dumble collector/historian/Dealer and someone who knows as much about Dumble's amps as you? why he would call one amp a Bass amp and one a guitar amp?...Really doesn't interest you at all huh? Ok
https://ampgarage.com/forum/viewtopic.p ... 678#p55678
Thanks for the reply.

Tony

[Max]

… As to why he used this transformer i can only guess, … https://ampgarage.com/forum/viewtopic.p ... 96#p427296

In this interview https://ampgarage.com/forum/viewtopic.php?f=4&t=22012 Alexander Dumble explains why he started using Dynaco transformers:

... Then, Jack and I made some Dual showman-type amps, although we couldn't get Fender transformers--they were very tight about what they'd send you--so we used David Hafler transformers, which made the amp sound quite extraordinary. ...

David Hafler was one of the two founders of Dynaco: https://en.wikipedia.org/wiki/Dynaco

Best regards,

Max

[mojotom]

Here is the schematic of what we believe to be Dumbleland Special 150w ser#009 collected from the Amp Garage and other reliable outside sources who are familiar with the Dumbleland topology,unfortunately no detailed gut shots of an actual specimen have yet to surface, so we are calling this version unverified for now? ,however, all of these circuits used were imported from other amplifiers from the Dumble line, Odyssey,Winterland, and the Steel String Singer.
We believe Dumble used these similar type circuits in his Dumbleland Specials .So for those out there who wish to share any detailed knowledge about #009 or any Dumbleland Special we would be grateful and honored to update our schematic.. Feel free to PM me if you wish to be discreet...Here we go....

REVISED SCHEMATIC.jpg

Here are some specs from ser#009 Built in 1978
7025/ input/tone stack recovery
7025/Filter recovery
12AU7 L.T.P Phase inverter
12BH7 A.C coupled Driver
4X6550 Output tubes
Classic tone stack
Hi/Lo Filters 7 step
Deep/Rock-Jazz/Bright
Accent
Output power rated @137 watts continuous
Inputs/Normal no FET
4-8-16 Ohm Selectable
Pre amp out

Power transformer looks to be Triad R-25A made 42nd week of 1968
Output transformer Schumacher OT. EIA code 606 is from a Sunn 1200S (4x6550) amp. The Sunn original part# is 28-1312, 3-120T output transformer.
Date of Mfg says 1971
Schumacher.jpeg
Some History
Dumble manufactured the Dumbleland amp from 1966 to around 1986 some voiced for Bass others guitar and was the forerunner to the later SSS model amplifier for lead guitar
Dumbleland Bass 150W $ 3,145.00
Dumbleland Special 150W $ 3,390.00
Dumbleland Special 300SL $ 3,935.00

For those builders planning to use the schematic as a baseline for their Dumbleland inspired build.Here are a few other ideas for modifications that would be easy to implement or change!
1. 2nd or 3rd generation tone stack
2. Martin Mannings filter array (voiced for guitar)
3. Convert the unused triode in V2B to a DC coupled cathode follower to help drive any outboard gear.
4.Different power and output tube combinations
5.footswitchable FET to drive the front end
https://ampgarage.com/forum/viewtopic.p ... _0139.jpeg

PI and Driver setup
As far as the various parts and circuits that make up the Dumbleland design The early 200W (4xKT88) Winterland has been the forerunner of the Dumbleland for guitar and bass and the Dumbleland for guitar has been the forerunner of the SSS.The SSS uses a completely different PI/Driver structure than the Dumblelands. The SSS style PI/Driver section commonly uses 2X 7025 preamp tubes, consisting of a LTP style PI, with an S.V.T style Driver section, whereby, the grids of the power tubes are D.C driven by the low impedance side of the cathodes of the 7025's,(correct terminology being "cathode follower driver"). The Odyssey's is similar to a L.T.P phase inverter are A.C driven to the grids of the power tubes via the plates of a 12BH7 driver tube. Benefits of the BH7 come with an increased current handling capability, therefore delivering a smooth, punchier more responsive,sound and feel.The Odyssey which was also used for guitar by players like Eric Johnson (who owns a very early Odyssey) As far as we know Alexander Dumble used this (12AU/BH7) PI driver structure in a lot of his amps.
Pictures and a schematic of the Odyssey
https://ampgarage.com/forum/viewtopic.p ... seyFilters
https://ampgarage.com/forum/viewtopic.p ... +schematic
FILTERS
Filter values were taken from SSS# 002 from this hand drawn schematic https://ampgarage.com/forum/viewtopic.php?f=5&t=17827, #002 also used a Triad SP-118 inductor to feed the filters. This is considered optional Read here: https://ampgarage.com/forum/viewtopic.p ... r&start=15
The filters in 002 have been known to cause complaints by several builders that has used the same values. Because of these complaints a different filter array was developed better suited for the frequency range for guitar, by member Martin Manning..Thank you MM
http://ampgarage.com/forum/viewtopic.ph ... 57#p378857
SSS_Step_Filters1_MPM.png


Tone Stack
Although the transformer codes on ser#002 latest reads 1977 and uses what's known as the "Classic" tone stack and Ser# 009 Dumbleland was AFAWK built in 1978 there seems to be some discrepancies as to when Dumble implemented his "Classic". The 78 time frame would perhaps more accurately coincide with either 2nd or 3rd generation tone stack which you can find Dumble used in his earlier 2nd/3rd Generation ODS amps. This is why the tone stack is still not yet verified.

https://ampgarage.com/forum/viewtopic.php?f=5&t=12870
https://ampgarage.com/forum/viewtopic.php?f=5&t=12871

Be aware that these type stacks used in these 2nd or 3rd gen amps w/james configuration used different pot values and therefore respond differently and can have a slightly narrower ranging E.Q than the later Classics. AFAIK in 1978 Dumble did not equip his Dumblelands with a Skyliner tone stack.
There are also several different versions of these earlier type tone stacks you can read about here.https://ampgarage.com/forum/viewtopic.p ... 75#p126317
(BTW.for those members looking for something closer to that of a Fender AB763 sounding stack? the Classic would be better suited to this taste)
ULTRA LINEAR
The Dumbleland's Output transformer is equipped with ultra linear taps, this enables you to run the output tubes at higher plate voltages for increased power output, given that the screens of 6550 are not designed to handle these higher voltages under load, the U.L taps provide a kind of negative feedback which helps regulate the screen supply under heavy load conditions for extended periods. So if one is to run these output tubes plates at 540/550 VDC ultra linear operation is recommended. (The earlier model Winterlands were also equipped with U.L taps) #003
https://ampgarage.com/forum/viewtopic.php?f=5&t=3668
U.L operation also lowers THD% and increases the damping factor..If one decides to go with the standard Fender/Twin style off the shelf and run 6l6's@ 450VDC there is no need for the taps, although, this could also alter the sound, performance,feel of the amplifier,

Many Thanks to Aaron Griffin Sleepwalk studios for drawing up the schematic and anyone else who posted and contributed to get this project started!!

I thought about this one as a base for a Bass amp and did some researches.
Didn’t the UL taps amps usually use a resistors rather than a choke (due to the screens tied to the output transformer) ?
Does 009 use a choke ?

[Richard1001]

There is a choke in the 009, but there are also chokes in the winterland (UL bass amp), Sunn 1200S (also UL) and plenty of other UL amps. So i don't think it gives a sure answer.

[talbany]

Max
Could it be that one of the reasons why he calls it a Bass amp is because he used an output transformer off a Bass amp . Therefore intended it to be used like a bass amp (with the taps). He also calls the Winterland #003 004 built for M.Husser a "Bass amp". The Winterland also has U.L taps and So does the Dumbleland #009 (that you call a 'Bass amp"). Perhaps then it makes sense from a design standpoint that Dumble used the U.L feature in what he calls a "Bass Amp" and since U.L was used in other Bass amps too like the Sunn 2000 (the very amp he pulled the output from) . Could it also be a reason why Dumble stipulates The Dumbleland as "Too silky clean" accept for S.R.V. who also used a Dumbleland @ J.B studio which he too calls a "Bass Amp" at the same time refers to Stevies SSS"s as set up like a "Bass amp" and guess what? same Sunn transformer's that are off a "Bass amp" (w/ taps) ..See where I am going with this?.. I know this doesn't prove anything but still ask? Why does Dumble classify the Dumbleland as a "Bass amp" could part of the reason be that he is running U.L to increase clean headroom and lower THD like other bass amps use it?. Being a historian/ collector would figure this would be of some interest to you> no?... It is me

There are no conspiracy's but there are also no coincidences
https://www.tdpri.com/threads/dumble-winterland.193857/
Tony

[Max]

AFAIR, Alexander Dumble has not commented on the question of whether DLS#009 is a guitar amplifier or a bass amplifier in any interview published so far.

AFAIK, some well-known manufacturers of tube amplifiers used the same power amplifiers in their contemporaneous models for bass and guitar (e.g.: Marshall 1986/1987, 1992/1959, 1978/1967 - Ampeg SVT/V9 - Sunn 2000S/1200S).

And according to this catalog: http://www.preservationsound.com/wp-con ... atalog.pdf

... the Sunn 1200 (the very amp he pulled the output from) ...

isn't a bass amp but the "Ultimate lead or rhythm guitar amp".

My personal opinion still is:

… that both options may be conceivable in regard to Dumbleland Special 150W #009: An output stage with connected UL taps and an output stage without connected UL taps. https://ampgarage.com/forum/viewtopic.p ... 92#p427492

Best regards,

Max

[talbany]

According to this catalog, the Sunn 1200S is an "Ultimate lead or rhythm guitar amp": http://www.preservationsound.com/wp-con ... atalog.pdf

According to the schematic of the Sunn 2000 listed as the Ultimate Bass amp has the same output transformer as the 1200 listed as a guitar amp 3 120 T output transformer (120 watts RMS/ 280 watts peak) 4X6550

http://www.prowessamplifiers.com/schema ... _2000s.pdf
http://www.prowessamplifiers.com/schema ... ematic.pdf

AFAIK, some well-known manufacturers of tube amplifiers use the same power amplifiers in their contemporaneous models for bass and guitar (e.g. Marshall Major, Ampeg SVT/V9, Sunn 1200S/2000S)

Back in the 70's some amp manufactures combined a high powered output section (similar to that of a Bass amp for max clean headroom) and voiced the pre amp for guitar. What you get is a very loud,very clean guitar amp w/ no output distortion. (some used U.L taps like Major and the 1200S).
Since most guitar amps of that time lack the power and current handling capability to drive the lower frequency range for a bass guitar, they run out of clean headroom and begin to distort at louder volume settings for big stages. In the case with the D-land I can see why Dumble was able to call both guitar and Bass due to the Hi/Lo filter section, gives you the flexibility to set the pre amp up for either guitar or Bass . What I believe Dumble is referring to when he says "set up like a Bass amp" he is referring to the current amplifier (output section) and not the voltage amplifier (pre amp)

"There are some different things about Stevie's" (SSS) "His is set up more like a bass amp, modified to accomodate the guitar range." (Dumbleland Special for guitar) "It's not the usual lead guitar "Singer" approach."

Again!
What I see written here tells me ?.. Stevies SSS is set up like a Bass amp (referring to the output section) and Accommodate the guitar range? (mainly referring to the pre amp section )
"It's not the usual lead guitar "Singer" approach. (Because the SSS has a different output section than a Dumbleland)

AFAIR, Alexander Dumble has not commented on the question of whether DLS#009 is a guitar amplifier or a bass amplifier in any interview published so far.

Of course your not going to find him commenting about a specific serial number amp

I didn't change a whole lot about that; it was a design way ahead of its time. It was too much power and too silky clean for people. It's perfect for Stevie Ray, though. He has a hard time playing an Overdrive.

Dumble did say that the amp S.R.V used for Texas flood recording was a "Bass Amp"

I am selling my 1978 150W Dumble Dumbleland Special, It is in fantastic condition and sounds incredible. This amp is the exact specification as the one Stevie Ray Vaughan recorded Texas Flood

https://reverb.com/item/94472-dumble-du ... light-case
Tony

[Roe]

Why not contact the owner of SRVs amps to document his Dumbles in the name of history and science?

Cf. https://grammymuseum.org/museum-at-home ... y-vaughan/

[Max]

... Dumble did say that the amp S.R.V used for Texas flood recording was a "Bass Amp" and last I looked it said Dumbleland on it! and had the filters. ...

In my opinion, we should always keep in mind that this theory (Jackson Browne’s Texas Flood bass amp = Jackson Browne DLS150W) is a result of educated guesswork. AFAIR Alexander Dumble (and SRV, Jackson Browne, band members, other eyewitnesses in Jackson Browne's studio) never explicitly said, that Jackson Browne's Texas Flood bass amplifier is actually Jackson Browne's Dumbleland Special 150W.

So in my opinion this (Jackson Browne's Texas Flood bass amp = Jackson Browne's DLS150W) is indeed a very plausible theory. But there are also other reports, such as e.g., this one:

... Indeed, SRV did use Jackson Browne's gold panel old Dumbleland Bass amp to record the Texas Flood album ... https://ampgarage.com/forum/viewtopic.p ... 656#p27656

And IMO this report is not completely implausible either. Because such a "gold panel" amp with the dimensions and the usual controls (exception: presence control instead of accent switch) of a Dumbleland with filters and with the model designation "Dumble Special" is actually pictured in "A Dumble Book by Jesse Schwarz" on pages 179 and 194 (standing vertically on the floor).

Best regards,

Max

[Richard1001]

I am selling my 1978 150W Dumble Dumbleland Special, It is in fantastic condition and sounds incredible. This amp is the exact specification as the one Stevie Ray Vaughan recorded Texas Flood

https://reverb.com/item/94472-dumble-du ... light-case
Tony

If i was selling this amp, i would say the same thing...

I don't think there is a sure way to come up with the answer with regard to UL or non UL without the amp or gutshots. So i think it would be an idea to just assume it's either one or the other and work from that. Let's assume you are right and the silky clean is reference to an UL poweramp.
My assumption is that there is a choke feeding the b+ for the tubes like the Winterland. I assume the powersupply has 47-47uf in series on the rectifier, nex standby, next a choke and than 100 - 100 uf in series where the output transformer is connected.

[Max]

In addition to decisions in relation to the output stage and power supply circuits assumed for DLS150W#009, as far as I understand it, there may also be decisions pending in relation to possible updates of the assumptions regarding the preamp of DLS150W#009?:

As I understand it, the current poposal is largely based on the assumption that DLS150W#009 - with the exception of the reverb - has more or less the same - or at least a very similar - preamp as SSS100W#002.

And with regard to SSS100W#002, here https://ampgarage.com/forum/viewtopic.php?f=4&t=33419 some opinions have been posted in the last few weeks that might suggest that the preamp circuit currently proposed by Aaron and talbany for DLS150W#009 may need to be updated?

Best regards,

Max

[didit]

Hello -

The "block" schematic of #12 provided a while back has a 10K resistor tapped to 4 Ohm providing negative feedback. Common for some GNFB even with localize feedback from UL screens. Perhaps a clue in that based on the value as to whether #12 is or isn't. Which may or may not have anything to say about #009. Or #6 or double oh seven for that matter.



====
Best .. Ian

[Richard1001]

In addition to decisions in relation to the output stage and power supply circuits assumed for DLS150W#009, as far as I understand it, there may also be decisions pending in relation to possible updates of the assumptions regarding the preamp of DLS150W#009?:

As I understand it, the current poposal is largely based on the assumption that DLS150W#009 - with the exception of the reverb - has more or less the same - or at least a very similar - preamp as SSS100W#002.

And with regard to SSS100W#002, here https://ampgarage.com/forum/viewtopic.php?f=4&t=33419 some opinions have been posted in the last few weeks that might suggest that the preamp circuit currently proposed by Aaron and talbany for DLS150W#009 may need to be updated?

Best regards,

Max

You are right, the input network to the switches and the wiring of the switches needs to be updated too.

[talbany]

Deleted

[Max]

With regard to corrections to the preamp circuit, which was suggested here in the first post by Aaron and talbany for DLS150W#009, as I understand it, it is particularly a matter of another careful comparison between this suggestion

REVISED SCHEMATIC.jpg

and maybe this hand drawn schematic (“Filter values were taken from … this hand drawn schematic”)

SSS SN002.jpg

SSS SN002 PS.jpg

with the picture(s?) of the preamp of SSS100W#002 known here:

Screen Shot 2012-04-15 at 5.17.40 PM.png

And maybe all members here (if interested) could take part in this review?

Best regards,

Max